@prefix vivo: . @prefix edm: . @prefix ns0: . @prefix dcterms: . @prefix skos: . vivo:departmentOrSchool "Applied Science, Faculty of"@en, "Mechanical Engineering, Department of"@en ; edm:dataProvider "DSpace"@en ; ns0:degreeCampus "UBCV"@en ; dcterms:creator "Nyborg, Erling Orvald"@en ; dcterms:issued "2011-06-02T12:23:58Z"@en, "1970"@en ; vivo:relatedDegree "Doctor of Philosophy - PhD"@en ; ns0:degreeGrantor "University of British Columbia"@en ; dcterms:description """Raspberry growers in the lower mainland of British Columbia are contending with increasing production costs and are facing problems in obtaining seasonal labour for fruit picking. Since cost of hand harvesting represents a large proportion of the total production cost, the purpose of this research was to investigate the feasibility of mechanical raspberry harvesting and to design a mechanical harvesting system suitable for the lower mainland of British Columbia. A systematic design procedure, oriented toward design and testing of a bio-machine system, was employed and the selected design was based upon the physical and mechanical properties of the raspberry plant and its fruit. An economic analysis, comparing the mechanical harvesting system to present hand harvesting methods was used to determine the necessary relationships among machine cost, machine capacity and machine efficiency. The selected design for a mechanical raspberry harvesting system included tools for feeding, cane orientation, selective harvesting, fruit collection, fruit conveying and fruit storage. Mathematical models for these tools were constructed, based on a series of tests determining pertinent physical and mechanical properties of the raspberry plant and fruit. In addition, tests to define fruit quality were undertaken and the relationships among fruit quality and selective harvesting parameters were investigated. The use of chemical growth, regulator's to alter fruit retention force was also investigated. Force-deformation moduli, resulting from flat plate compression tests of raspberry fruit, were found to be good indicators of fruit quality. Correlations among force-deformation moduli and fruit properties indicated that either fruit retention force or F/W ratio could be used as control variables for a selective harvesting tool. Prototype units for feeding, cane orientation and selective harvesting tools were designed and fabricated. The selective harvesting tool was a fixed displacement shaker designed to apply equal maximum acceleration to all fruiting portions of the plant, independent of plant properties. F/W ratio was used as the control variable for selective harvesting. Limited field testing indicated that the tools for feeding, cane orientation and selective harvesting could satisfactorily be used in a mechanical raspberry harvesting system. Results also indicated that mechanical harvesting could be substantially more profitable than hand harvesting. The Willamette variety of raspberries as commonly grown in British Columbia was found not especially suitable for mechanical harvesting. Due to the high ratio of fruit retention force to fruit stem strength in the Willamette variety, the quality of machine harvested fruit must be lower than the quality of hand harvested fruit. Since fruit retention force is dependent upon fruit variety, investigation of physical properties of other suitable raspberry varieties should be undertaken in order to find a variety having properties more compatible with mechanical harvesting methods."""@en ; edm:aggregatedCHO "https://circle.library.ubc.ca/rest/handle/2429/35054?expand=metadata"@en ; skos:note "MECHANICAL RASPBERRY HARVESTING BY ERLING ORVALD NYBORG B.E., U n i v e r s i t y o f Saskatchewan, 1960 M.S., M i c h i g a n S t a t e U n i v e r s i t y , 1967 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n t h e Department o f M e c h a n i c a l E n g i n e e r i n g We a c c e p t t h i s t h e s i s as c o n f o r m i n g to' t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA F e b r u a r y , 1970 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r equ i r emen t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I ag ree tha t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . 1 f u r t h e r agree tha p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y pu rposes may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d tha t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t hou t my w r i t t e n p e r m i s s i o n . Department o f Mechanical Engineering The U n i v e r s i t y o f B r i t i s h Co lumbia Vancouve r 8, Canada Date A p r i l 20, 1970. ABSTRACT Raspberry growers i n the lower mainland of B r i t i s h Columbia are contending with i n c r e a s i n g production c o s t s and are f a c i n g problems i n o b t a i n i n g seasonal labour f o r f r u i t p i c k i n g . Since cost of hand h a r v e s t i n g represents a l a r g e p r o p o r t i o n of the t o t a l production c o s t , the purpose of t h i s research was to i n v e s t i g a t e the f e a s i b i l i t y of mechanical raspberry h a r v e s t i n g and to design a mechanical h a r v e s t i n g system s u i t a b l e f o r the lower mainland of B r i t i s h Columbia. A systematic design procedure, o r i e n t e d toward design and t e s t i n g of a bio-machine system, was employed and the s e l e c t e d design was based upon the p h y s i c a l and mechanical p r o p e r t i e s of the raspberry p l a n t and i t s f r u i t . An economic a n a l y s i s , comparing the mechanical h a r v e s t i n g system to present hand .harvesting methods was used to determine the necessary r e l a t i o n -ships among machine c o s t , machine c a p a c i t y and machine e f f i c i e n c y . The s e l e c t e d design f o r a mechanical raspberry h a r v e s t i n g system i n c l u d e d t o o l s f o r fe e d i n g , cane o r i e n t a t i o n , s e l e c t i v e h a r v e s t -i n g , f r u i t c o l l e c t i o n , f r u i t conveying and f r u i t storage. Mathematical models f o r these t o o l s were c o n s t r u c t e d , based on a s e r i e s of t e s t s determining p e r t i n e n t p h y s i c a l and mechanical p r o p e r t i e s of the raspberry p l a n t and f r u i t . In a d d i t i o n , t e s t s to d e f i n e f r u i t q u a l i t y were undertaken and the r e l a t i o n s h i p s among f r u i t q u a l i t y and s e l e c t i v e h a r v e s t i n g parameters were i n v e s t i g a t e d . The use of chemical growth, regulator's t o a l t e r f r u i t r e t e n t i o n f o r c e was a l s o i n v e s t i g a t e d . Force-deformation moduli, r e s u l t i n g from f l a t p l a t e compression t e s t s of r a s p b e r r y f r u i t , were found to be good i n d i c a t o r s o f f r u i t q u a l i t y . C o r r e l a t i o n s among f o r c e - d e f o r m a t i o n moduli and f r u i t p r o p e r t i e s i n d i c a t e d t h a t e i t h e r f r u i t r e t e n t i o n f o r c e or F/W r a t i o c o u l d be used as c o n t r o l v a r i a b l e s f o r a s e l e c t i v e h a r v e s t i n g t o o l . Prototype u n i t s f o r f e e d i n g , cane o r i e n t a t i o n and s e l e c t i v e h a r v e s t i n g t o o l s were designed and f a b r i c a t e d . The s e l e c t i v e h a r v e s t i n g t o o l was a f i x e d d i s p l a c e -ment shaker designed t o a p p l y equal maximum a c c e l e r a t i o n t o a l l f r u i t i n g p o r t i o n s o f the p l a n t , independent o f p l a n t p r o p e r t i e s . F/W r a t i o was used as the c o n t r o l v a r i a b l e f o r s e l e c t i v e har-v e s t i n g . L i m i t e d f i e l d t e s t i n g i n d i c a t e d t h a t the t o o l s f o r f e e d i n g , cane o r i e n t a t i o n and s e l e c t i v e h a r v e s t i n g c o u l d s a t i s f a c t o r i l y be used i n a mechanical r a s p b e r r y h a r v e s t i n g system. R e s u l t s a l s o • i n d i c a t e d t h a t mechanical h a r v e s t i n g c o u l d be s u b s t a n t i a l l y more p r o f i t a b l e than hand h a r v e s t i n g . The W i l l a m e t t e v a r i e t y of r a s p b e r r i e s as commonly grown i n B r i t i s h Columbia was found not e s p e c i a l l y s u i t a b l e f o r mechanical h a r v e s t i n g . Due to the h i g h r a t i o o f f r u i t r e t e n t i o n f o r c e to f r u i t stem s t r e n g t h i n the W i l l a m e t t e v a r i e t y , the q u a l i t y o f machine h a r v e s t e d f r u i t must be lower than the q u a l i t y o f hand h a r v e s t e d f r u i t . Since f r u i t r e t e n t i o n f o r c e i s dependent upon f r u i t v a r i e t y , i n v e s t i g a t i o n of p h y s i c a l p r o p e r t i e s o f o t h e r s u i t a b l e r a s p b e r r y v a r i e t i e s should be undertaken i n o r d e r t o f i n d a v a r i e t y having p r o p e r t i e s more compatible with mechanical har-v e s t i n g methods. TABLE OF CONTENTS Page LIST OF TABLES i x LIST OF FIGURES x i TERMINOLOGY x i v NOMENCLATURE x v i i i ACKNOWLEDGMENTS x x i i INTRODUCTION 1 P r e s e n t S t a t u s o f R a s p b e r r y P r o d u c t i o n i n B r i t i s h C olumbia 1 The need f o r h a r v e s t m e c h a n i z a t i o n 1 Scope and Purpose o f t h i s R e s e a r c h 2 • Review o f P r e v i o u s Work 2 C a t e g o r i e s o f h a r v e s t i n g systems 3 Methods o f f r u i t r e m o v a l 4 SYSTEMATIC DESIGN PROCEDURE 7 ANALYSIS OF THE PROCESS 10 Flow C h a r t 10 O p e r a t i o n a l Requirements o f t h e H a r v e s t i n g Machine 10 I n i t i a l c o n d i t i o n 10 F i n a l c o n d i t i o n 14 Economic A n a l y s i s o f R a s p b e r r y H a r v e s t i n g 14 Cost o f hand p i c k i n g 14 Y i e l d s and market p r i c e 15 E s t i m a t e d c o s t o f m e c h a n i c a l h a r v e s t i n g 15 The br e a k - e v e n p o i n t 18 Summary o f Machine Requirements 21 - v -Page TOOL ANALYSES 2 3 M e c h a n i z a t i o n o f the P r o c e s s 23 T o o l f o r F e e d i n g and Cane O r i e n t a t i o n 23 F u n c t i o n 23 Proposed d e s i g n 24 A n a l y s i s 25 Unknowns 27 T o o l f o r S e l e c t i v e H a r v e s t i n g 27 F u n c t i o n 27 Proposed d e s i g n 27 A n a l y s i s 29 Unknowns 30 T o o l f o r F r u i t C o l l e c t i o n and Conveying 31 F u n c t i o n 31 Proposed d e s i g n 31 A n a l y s i s 32 Unknowns 3 3 T o o l f o r F r u i t S t o r a g e 34 F u n c t i o n 34 Proposed d e s i g n 34 A n a l y s i s 34 Unknowns 35 Summary 3 5 ANALYSIS OF PRODUCT CHARACTERISTICS 36 Scope o f I n v e s t i g a t i o n 36 D i s t r i b u t i o n o f F r u i t on t h e R a s p b e r r y P l a n t 36 P h y s i c a l Dimensions o f R a s p b e r r y P l a n t s 39 - v i -Page P h y s i c a l Dimensions o f the Raspberry F r u i t and Stem 39 F r u i t Weight, Volume and D e n s i t y 40 Rate of F r u i t Removal 41 Term i n a l V e l o c i t y o f Raspberry F r u i t 41 F r u i t R e t e n t i o n Force 4 2 F/W R a t i o 45 St r e n g t h o f F r u i t Attachment System 4 6 F r u i t C o l o r 48 B r u i s i n g C h a r a c t e r i s t i c s o f Raspberry F r u i t 52 Force-Deformation C h a r a c t e r i s t i c s o f Raspberry F r u i t 53 F r u i t R i g i d i t y 55 Sugar Content of F r u i t 57 Comparison o f P r o p e r t i e s i n an Attempt t o Def i n e F r u i t Q u a l i t y 58 Dynamic Response o f Canes and F r u i t Attachment System 63 E l a s t i c Modulus o f Raspberry Canes 70 C o n t r o l o f P h y s i c a l P r o p e r t i e s - Growth Reg u l a t o r s 71 MATHEMATICAL MODELS FOR THE TOOLS 8 0 Completion o f the T o o l Analyses 80 T o o l f o r Feeding and Cane O r i e n t a t i o n 80 T o o l f o r S e l e c t i v e H a r v e s t i n g 84 T o o l f o r F r u i t C o l l e c t i o n and Conveying 88 T o o l f o r F r u i t Storage 91 DESIGN AND FABRICATION OF TOOLS 91 I n t r o d u c t o r y Remarks 9 3 T o o l f o r Feeding and Cane O r i e n t a t i o n 93 To o l f o r S e l e c t i v e H a r v e s t i n g 95 - v i i -Page F r u i t C o l l e c t i o n , Conveying and Storage 97 SYNTHESIS AND CONSTRUCTION OF THE MACHINE 99 Purpose of the Prototype Machine 99 Powering Systems 99 Frame and Supporting Members 102 T r e l l i s i n g M o d i f i c a t i o n 102 MACHINE EVALUATION 104 Scope o f Tes t 104 E v a l u a t i o n o f the Feeding and Cane O r i e n t a t i o n T o o l 104 E v a l u a t i o n o f the S e l e c t i v e H a r v e s t i n g T o o l 105 E v a l u a t i o n o f Machine C o n s t r u c t i o n 109 Concluding Remarks 110 OBSERVATIONS AND CONCLUSIONS 112 SUGGESTIONS FOR FURTHER STUDY 117 LITERATURE CITED 118 • • • - V11X -LIST OF TABLES T a b l e Page I R a s p b e r r y P r o d u c t i o n i n t h e Lower M a i n l a n d o f B r i t i s h Columbia 14 I I E s t i m a t e d Cost o f M e c h a n i c a l H a r v e s t i n g 17 I I I P h y s i c a l Dimensions o f the R a s p b e r r y F r u i t and i t s Attachment Stem 4 0 IV C a l c u l a t e d Rate o f F r u i t Removal f o r a S i n g l e Row H a r v e s t i n g Machine 41 V R e s u l t s o f Drop T e s t s 53 VI S i m p l e C o r r e l a t i o n s Among R i g i d i t y and F r u i t Dimensions 57 V I I S i m p l e C o r r e l a t i o n s Among F r u i t R e t e n t i o n F o r c e , F r u i t Weight and F r u i t Sugar C o n t e n t 58 V I I I S i m p l e C o r r e l a t i o n s Among F r u i t R e t e n t i o n F o r c e , F / W , R i g i d i t y and F o r c e - D e f o r m a t i o n M o d u l i 59 IX S i m p l e C o r r e l a t i o n s Among C o l o r I n d e x , F r u i t R e t e n t i o n F o r c e , F/W, R i g i d i t y and F o r c e - D e f o r m a t i o n M o d u l i f o r t h e F i r s t Day o f the 1968 H a r v e s t Season 62 X Si m p l e C o r r e l a t i o n s Among C o l o r Index, F r u i t R e t e n t i o n F o r c e , F/W, R i g i d i t y and F o r c e - D e f o r m a t i o n M o d u l i f o r t h e F i f t e e n t h Day o f t h e 1968 H a r v e s t Season 62 XI F l e x i b i l i t y M a t r i x , [ C ] , f o r a R a s p b e r r y Cane Loaded as a V e r t i c a l C a n t i l e v e r Beam 66 X I I Mass M a t r i x , [\"m J , f o r a R a s p b e r r y Cane 67 X I I I Growth R e g u l a t o r Treatments 74 XIV V a r i a t i o n o f F r u i t R e t e n t i o n F o r c e w i t h Time as A f f e c t e d by Growth R e g u l a t o r Treatments 77 XV V a r i a t i o n o f F r u i t Weight w i t h Time as A f f e c t e d by Growth R e g u l a t o r Treatments 78 XVI F/W V a r i a t i o n w i t h Time as A f f e c t e d by Growth R e g u l a t o r Treatments 79 X V I I Means and S t a n d a r d D e v i a t i o n s o f F r u i t R e t e n t i o n F o r c e and F/W R a t i o Based on Data C o l l e c t e d i n 1968 85 - i x -T a b l e Page X V I I I C a l c u l a t e d Base M o t i o n A c c e l e r a t i o n f o r S e v e r a l L e v e l s o f F r u i t Removal E f f i c i e n c y 87 - x -LIST OF FIGURES i g u r e 1 S y s t e m a t i c d e s i g n p r o c e d u r e 2 D e f i n i n g t h e p r o c e s s 3 Flow c h a r t s f o r hand h a r v e s t i n g and f o r t h e p r o p osed m e c h a n i c a l h a r v e s t i n g system 4 A t y p i c a l row o f W i l l a m e t t e r a s p b e r r i e s 5 The r a s p b e r r y f r u i t 6 The e f f e c t o f machine pur c h a s e p r i c e on the b r e ak-even p o i n t f o r a machine c a p a c i t y o f one a c r e p e r hour 7 The e f f e c t o f machine c a p a c i t y on t h e b r e a k -even p o i n t f o r a machine p u r c h a s e p r i c e o f $3,500 8 T o o l f o r f e e d i n g and cane o r i e n t a t i o n 9 A r a s p b e r r y cane i d e a l i z e d as a t a p e r e d v e r t i c a l c a n t i l e v e r beam o f c i r c u l a r c r o s s s e c t i o n 10 T o o l f o r s e l e c t i v e h a r v e s t i n g 11 C u m u l a t i v e d i s t r i b u t i o n o f f r u i t on a r a s p b e r r y p l a n t as measured upward from th e s o i l s u r f a c e 12 C u m u l a t i v e d i s t r i b u t i o n o f f r u i t on a r a s p b e r r y p l a n t as measured outward from t h e c e n t e r o f t h e row o f p l a n t s 13 P h y s i c a l d i m e n s i o n s o f a r a s p b e r r y p l a n t 14 Nomenclature used i n T a b l e I I I 15 Method o f measuring f r u i t r e t e n t i o n f o r c e 16 Method o f h o l d i n g f r u i t i n t h e dynamometer 17 F r u i t r e t e n t i o n f o r c e v a r i a t i o n o v e r th e h a r v e s t season f o r 1967 and 1968 18 C u m u l a t i v e d i s t r i b u t i o n o f f r u i t r e t e n t i o n f o r c e f o r 1968 19 C u m u l a t i v e d i s t r i b u t i o n o f F/W f o r 1968 - x i -F i g u r e Page 20 R a s p b e r r y f r u i t a t t a c h m e n t system 47 21 V a r i a t i o n o f f r u i t stem s t r e n g t h w i t h l o a d d i r e c t i o n 47 22 C u m u l a t i v e d i s t r i b u t i o n o f f r u i t stem s t r e n g t h f o r a = 0° 47 23 S p e c t r o p h o t o m e t e r m o d i f i c a t i o n 50 24 T u r n t a b l e and e x t e r n a l l i g h t s o u r c e 50 2 5 Complete i n s t r u m e n t a t i o n f o r measuring e x t e r n a l c o l o r o f r a s p b e r r y f r u i t 51 26 V a r i a t i o n o f f r u i t c o l o r as d e t e r m i n e d by r e f l e c t a n c e measurements 51 27 Method o f l o a d i n g f r u i t i n I n s t r o n machine 54 28 T y p i c a l f o r c e - d e f o r m a t i o n c u r v e f o r r a s p b e r r y f r u i t s u b j e c t e d t o f l a t - p l a t e l o a d i n g a t 2 cm/min 54 29 I n s t r u m e n t a t i o n f o r me a s u r i n g f r u i t r i g i d i t y 56 30 F r u i t a t t a c h m e n t system i d e a l i z e d as a s i m p l e pendulum 64 31 Measurement o f t h e s t i f f n e s s i n f l u e n c e c o e f f i c i e n t s o f a r a s p b e r r y cane 65 32 C a l c u l a t e d modes o f v i b r a t i o n and c o r r e s p o n d i n g n a t u r a l f r e q u e n c i e s f o r two r a s p b e r r y canes 68 3 3 Randomized p l o t s f o r growth r e g u l a t o r t r i a l s 7 3 34 Spray boom f o r a p p l y i n g growth r e g u l a t o r s 7 3 35 E s t i m a t i n g t h e p o i n t o f c o n t a c t between t h e canes and t h e f e e d r o l l s 82 36 E s t i m a t i n g t h e d e f l e c t i o n o f t h e canes by t h e f e e d r o l l s 82 37 D e t e r m i n i n g cane t a p e r as a f u n c t i o n o f t h e p o i n t o f l o a d a p p l i c a t i o n 83 38 Base m o t i o n a p p l i e d t o t h e f e e d r o l l s 86 - x i i -F i g u r e Page 39 Maximum a c c e l e r a t i o n developed by a s l i d e r crank mechanism, wit h one f o o t c o n n e c t i n g rod l e n g t h , f o r s e v e r a l amplitudes and a range o f f r e q u e n c i e s 89 HO Feed r o l l f a b r i c a t i o n 94 41 Feed r o l l mounting and d r i v e t r a i n 94 42 Method of a p p l y i n g base motion to the feed r o l l s 96 43 Method o f v a r y i n g base motion amplitude 96 44 D r i v e t r a i n f o r a p p l y i n g the base motion 97 4 5 Nylon screens used as temporary c o l l e c t i o n and conveying t o o l s d u r i n g t e s t i n g of the t o o l s f o r f e e d i n g and s e l e c t i v e h a r v e s t i n g 98 46 P l a n view o f the h a r v e s t e r 100 47 Right view o f completed machine 101 48 Rear view o f completed machine 101 4 9 View o f machine e n t e r i n g a row. The m o d i f i e d t r e l l i s i n g system i s shown 103 « 50 106 51 106 52 106 53 F r u i t stem damage due to e x c e s s i v e base motion a c c e l e r a t i o n 108 54 The i n f l u e n c e o f f r u i t core shape on f r u i t r e t e n t i o n f o r c e 111 - x i i i -TERMINOLOGY A b s c i s s i o n l a y e r . - The r e g i o n on the f r u i t stem a t which n a t u r a l a b s c i s s i o n o c c u r s . A g g r e g a t e f r u i t . - A f r u i t formed by t h e r i p e n i n g t o g e t h e r o f a number o f s e p a r a t e o v a r i e s , a l l b e l o n g i n g t o a s i n g l e f l o w e r and a d h e r i n g as a u n i t on a common r e c e p t a c l e . A m p l i t u d e . - The maximum d i s p l a c e m e n t o f an o s c i l l a t i n g m o t i o n as measured from t h e mean p o s i t i o n . A n a l y s i s o f c o v a r i a n c e . - The a n a l y s i s o f c o v a r i a n c e as used i n t h i s s t u d y a p p l i e s t o a method o f comparing r e g r e s s i o n s i n m u l t i p l e c l a s s i f i c a t i o n s . I f t h e r e l a t i o n between Y and X i s o b t a i n e d f o r two i n d i v i d u a l t r e a t m e n t s , t h e model f o r the r e g r e s s i o n s i s Y i j = «i + 0 i X i j + «ij where i = 1,2 deno t e s t h e two t r e a t m e n t s . The method compares the r e s i d u a l v a r i a n c e s and °2^» compares t h e s l o p e s (3^ and ^ > a n d compares t h e e l e v a t i o n s o f t h e l i n e s «^ and • The p r o c e d u r e used i s o u t l i n e d on page 432 o f r e f e r e n c e ( 3 3 ) . A n a l y s i s o f v a r i a n c e . - A p r o c e s s by means o f which t h e t o t a l v a r i a n c e i n a co m p o s i t e sample i s a p p o r t i o n e d among the d i f f e r e n t f a c t o r s r e s p o n s i b l e f o r i t s g r o s s v a l u e . See, f o r example, pages 278 t o 436 o f r e f e r e n c e ( 2 8 ) . A n g l e modulus.- The a n g l e between t h e d e f o r m a t i o n a x i s and t h e i n i t i a l l i n e a r p o r t i o n o f t h e f o r c e - d e f o r m a t i o n c u r v e f o r r a s p b e r r y f r u i t compressed between p a r a l l e l f l a t p l a t e s a t a r a t e o f 2cm/min. Base m o t i o n . - The t y p e o f m o t i o n i m p a r t e d by a v i b r a t o r y h a r -v e s t i n g t o o l a t i t s p o i n t o f c o n t a c t w i t h a p l a n t . Break-even p o i n t . - The minimum n e c e s s a r y f r u i t r e m o v a l e f f i c i e n c y , i n p e r c e n t o f g r o s s f r u i t y i e l d , w h i c h must be a c h i e v e d by a m e c h a n i c a l h a r v e s t i n g machine, i n o r d e r t o o b t a i n t h e same g r o s s income from m e c h a n i c a l h a r v e s t i n g as i s p r e s e n t l y o b t a i n e d from hand h a r v e s t i n g . B r u i s i n g . - Damage t o p l a n t t i s s u e by e x t e r n a l f o r c e s c a u s i n g change i n t e x t u r e and/or e v e n t u a l c h e m i c a l a l t e r a t i o n o f c o l o r , f l a v o u r and t e x t u r e . B r u i s i n g does n ot break t h e s k i n . I n t h i s s t u d y , b r u i s e damage was e v a l u a t e d o n e - h a l f hour a f t e r l o a d i n g and was r e p o r t e d i n terms o f the maximum de p t h and mean w i d t h o f the b r u i s e d t i s s u e . - x i v -Cane.- The woody, p r o d u c t i v e , s e c o n d - y e a r growth o f t h e r a s p b e r r y p l a n t . Cane t a p e r . - When c o n s i d e r i n g a s p e c i f i c l e n g t h o f cane, cane t a p e r i s d e f i n e d as t h e mean r a d i u s o f t h e c r o s s - s e c t i o n o f the s m a l l end o f the cane d i v i d e d by t h e mean r a d i u s o f t h e c r o s s - s e c t i o n o f t h e l a r g e end o f t h e cane. C o e f f i c i e n t o f d e t e r m i n a t i o n . - In s i m p l e r e g r e s s i o n , t h e q u a n t i t y , r 2 , r e p r e s e n t i n g t h e f r a c t i o n o f t h e c o r r e c t e d sums o f s q u a r e s t h a t i s a t t r i b u t a b l e t o s i m p l e l i n e a r r e g r e s s i o n . See, f o r example, page 225 o f r e f e r e n c e ( 2 8 ) . C o e f f i c i e n t o f m u l t i p l e d e t e r m i n a t i o n . - I n m u l t i p l e r e g r e s s i o n , t h e q u a n t i t y , R 2 , r e p r e s e n t i n g the f r a c t i o n o f the sums o f s q uares o f t h e d e v i a t i o n s o f Y from i t s mean t h a t i s a t t r i b u t a b l e t o the r e g r e s s i o n . R 2 i s d e f i n e d as t h e sum o f s q u a r e s due t o r e g r e s s i o n d i v i d e d by t h e sum o f squares about th e mean. See, f o r example, page 402 o f r e f e r e n c e ( 3 3 ) . C o r e . - The r e c e p t a c l e on the end o f the f r u i t a t t a c h m e n t stem, around w h i c h t h e r a s p b e r r y f r u i t grows. D r u p e l e t s . - The i n d i v i d u a l r a s p b e r r y f r u i t l e t s , each o f w h i c h a r e formed from the r i p e n i n g o f s e p a r a t e o v a r i e s . The r a s p b e r r y f r u i t c o n s i s t s o f a number o f l o o s e l y bound d r u p e l e t s a t t a c h e d t o a c e n t r a l c o r e . , F i e l d e f f i c i e n c y . - The r a t i o o f e f f e c t i v e f i e l d c a p a c i t y t o t h e o r e t i c a l f i e l d c a p a c i t y . F i x e d d i s p l a c e m e n t s h a k e r . - A v i b r a t o r y h a r v e s t i n g t o o l i n w h i c h t h e a m p l i t u d e o f t h e a p p l i e d base m o t i o n i s c o n s t a n t . F r u i t f i r m n e s s . - The r e s i s t a n c e t o d e f o r m a t i o n o f f e r e d by a f r u i t under c o m p r e s s i v e l o a d . I n t h i s s t u d y , the t a n g e n t modulus o f t h e f o r c e - d e f o r m a t i o n c u r v e , r e s u l t i n g f r om c o m p r e s s i o n o f the f r u i t between p a r a l l e l f l a t p l a t e s a t a r a t e o f 2cm/min, was used as an i n d i c a t o r o f f r u i t f i r m n e s s . F r u i t r e t e n t i o n f o r c e . - The t e n s i l e f o r c e r e q u i r e d t o remove a r a s p b e r r y f r u i t from i t s c o r e . F r u i t r i g i d i t y . - I n t h i s s t u d y , r i g i d i t y was d e f i n e d as the a b i l i t y o f f r u i t t o t r a n s m i t m e c h a n i c a l v i b r a t i o n s . The i n t e n s i t y o f v i b r a t i o n s t r a n s m i t t e d t h r o u g h an i n d i v i d u a l f r u i t , compressed w i t h a f o r c e o f t e n grams between two p a r a l l e l d iaphragms, th e l o w e r diaphragm b e i n g e x c i t e d a t a f r e q u e n c y o f 250Hz, was used as an i n d i c a t o r o f f r u i t r i g i d i t y . -xv -Growth r e g u l a t o r . - An o r g a n i c compound which,when i n t r o d u c e d i n t o a p l a n t i n a r e l a t i v e l y s m a l l q u a n t i t y , i n d u c e s e f f e c t s on the growth p a t t e r n o f the p l a n t . I n e r t i a s h a k e r . - A v i b r a t o r y h a r v e s t i n g t o o l i n wh i c h t h e maximum f o r c e e x e r t e d by t h e a p p l i e d base m o t i o n i s c o n s t a n t . L i n e a r l i m i t . - The minimum l o a d a t wh i c h t h e f o r c e - d e f o r m a t i o n c u r v e , r e s u l t i n g from c o m p r e s s i n g r a s p b e r r y f r u i t between p a r a l l e l f l a t p l a t e s a t a r a t e o f 2cm/min, becomes non-l i n e a r . Mean.- The a r i t h m e t i c mean ,Mj o f a random sample o f indepe n d e n t o b s e r v a t i o n s . M u l t i p l e c o r r e l a t i o n c o e f f i c i e n t . - The square r o o t , R , o f t h e c o e f f i c i e n t o f m u l t i p l e d e t e r m i n a t i o n . P i c k i n g e f f i c i e n c y . - The p e r c e n t a g e o f mature f r u i t on a p l a n t w h i c h i s removed by a h a r v e s t e r . T h i s i s a l s o c a l l e d t he f r u i t r e m o v a l e f f i c i e n c y . PPM.- P a r t s p e r m i l l i o n . Random sample.- A sample c o n s i s t i n g o f in d e p e n d e n t o b s e r v a t i o n s w h i c h a r e drawn from a p o p u l a t i o n . R a s p b e r r y . - R a s p b e r r y , as used i n t h i s s t u d y , r e f e r s t o the American r e d r a s p b e r r y ( f a m i l y : Rosaceae, genus: Rubus, s p e c i e s : S t r i g o s u s , v a r i e t y : W i l l a m e t t e ) . Shoot.- The s u c c u l e n t , n o n - p r o d u c t i v e , f i r s t y e a r growth o f the r a s p b e r r y p l a n t . S i m p l e c o r r e l a t i o n c o e f f i c i e n t . - The square r o o t , r , o f the c o e f f i c i e n t o f d e t e r m i n a t i o n . S t a n d a r d d e v i a t i o n . - The s t a n d a r d d e v i a t i o n , D E 3 u 20 0 A harvest tirr:3,days 100 200 300 400 500 Upper Limit of Fruit Retention Force (grams) 600 F i g u r e 18 C u m u l a t i v e d i s t r i b u t i o n o f f r u i t r e t e n t i o n f o r c e f o r 1968 f o r f r u i t o f e q u a l m a t u r i t y , d e c r e a s e s as t h e h a r v e s t season p r o g r e s s e s . F u r t h e r m o r e , f r u i t r e t e n t i o n f o r c e appears t o be dependent upon growth c o n d i t i o n s i n a s p e c i f i c y e a r . F i g u r e 18 shows t h e c u m u l a t i v e d i s t r i b u t i o n f u n c t i o n o f f r u i t r e t e n t i o n f o r c e f o r t h e f i r s t day o f t h e h a r v e s t s e a s o n , the l a s t day o f t h e h a r v e s t season and f o r t h e whole h a r v e s t s e a s o n , based on t h e 1968 d a t a . The mean f r u i t r e t e n t i o n f o r c e on the f i r s t day o f h a r v e s t was 290.8 - 101.8 gm w h i l e on the l a s t day o f h a r v e s t , t h e mean f r u i t r e t e n t i o n f o r c e was 162.2 -142.2 gm, each v a l u e b e i n g based on e i g h t e e n measurements. F/W R a t i o F/W r a t i o was o b t a i n e d by combining t h e d a t a on f r u i t r e t e n t i o n f o r c e and f r u i t w e i g h t . Mean F/W f o r 1968 based on 90 samples was 82.8 - 65.1 w h i l e i n 1967 i t was 52.7 - 84.5, based on 124 measurements. The s i m p l e r e g r e s s i o n o f F/W on h a r v e s t t i m e f o r t h e 1968 d a t a i n d i c a t e d t h a t F/W d e c r e a s e d s i g n i f i c a n t l y w i t h i n c r e a s e i n t h e t i m e o f h a r v e s t . F/W = 128.0-6.5T, r 2 = 0 . 2 2 , n=90, S y=57.8 [24] f o r t h e range 1 < T < 15 where F/W = f r u i t r e t e n t i o n f o r c e / f r u i t w e i g h t T = t i m e i n d a y s , T=l b e i n g t h e f i r s t day o f h a r v e s t . Based on the 1968 d a t a and 18 measurements f o r each day, mean F/W was 96.2 - 44.8 on t h e f i r s t day o f t h e h a r v e s t s e a s o n , and was 46.4 - 43.3 on t h e l a s t day o f measurement (T=15). F i g u r e 19 shows t h e c u m u l a t i v e d i s t r i b u t i o n f u n c t i o n o f F/W f o r t h e 1968 h a r v e s t season. 100 200 300 Upper Limit of F/W F i g u r e 19 C u m u l a t i v e d i s t r i b u t i o n o f F/W f o r 1968 S t r e n g t h o f F r u i t A ttachment System The weakest p a r t o f t h e f r u i t a t t a c h m e n t system o c c u r s a t t h e p o i n t where t h e f r u i t stem a t t a c h e s t o the i n t e r m e d i a t e p l a n t stem ( f i g u r e 2 0 ) . Stem s t r e n g t h i s a f u n c t i o n o f d i r e c t i o n o f l o a d a p p l i c a t i o n ( f i g u r e 21) b e i n g g r e a t e s t when th e l o a d i s a p p l i e d upward ( a = 180°) p a r a l l e l t o t h e p l a n t stem and l e a s t when th e l o a d i s a p p l i e d downward p a r a l l e l t o t h e p l a n t stem (a = 0°). S i n c e the d i r e c t i o n o f l o a d a p p l i c a t i o n on t h e f r u i t stem i n a v i b r a t o r y h a r v e s t i n g machine i s unknown, measurement o f stem s t r e n g t h was based on a l o a d d i r e c t i o n o f a = 0°, r e s u l t i n g i n d e t e r m i n a t i o n o f minimum s t r e n g t h . Randomly s e l e c t e d samples, p i c k e d a t two d a t e s d u r i n g t h e 1969 h a r v e s t s e a s o n , were l o a d e d i n an I n s t r o n t e s t i n g machine. Stem s t r e n g t h was t a k e n as t h e 47 -1 0 0 0 Upper Limit of Stem Strength (grams) F i g u r e 22 Cum u l a t i v e d i s t r i b u t i o n o f f r u i t stem s t r e n g t h f o r a = 0° - 48 -maximum r e a d i n g on t h e f o r c e - d e f o r m a t i o n c u r v e i n each c a s e . Based on 132 samples, t h e mean and s t a n d a r d d e v i a t i o n o f stem s t r e n g t h was 177.1 - 164.3 grams. The c u m u l a t i v e d i s t r i b u t i o n f u n c t i o n f o r stem s t r e n g t h i s shown i n f i g u r e 22. One f u r t h e r t e s t was conducted i n o r d e r t o d e t e r m i n e t h e s i g n i f i c a n c e o f stem s t r e n g t h i n m e c h a n i c a l h a r v e s t i n g . A l l t h e mature f r u i t on one p l a n t was hand p i c k e d by a p p l y i n g a d i r e c t t e n s i l e f o r c e t o the f r u i t w h i l e m a i n t a i n i n g a ( f i g u r e 21) a t a p p r o x i m a t e l y 90°. In a t o t a l o f 63 f r u i t , 70 p e r c e n t were de t a c h e d from the c o r e w h i l e 3 0 p e r c e n t f a i l e d a t t h e stem w i t h t h e r e s u l t t h a t t h e c o r e and stem remained a t t a c h e d t o t h e h a r v e s t e d f r u i t . I n a c t u a l p r a c t i c e , hand p i c k i n g i s w i t h a r o l l i n g m o t i o n o f t h e f i n g e r s i n o r d e r t o l o o s e n the f r u i t from the c o r e . I n a v i b r a t o r y h a r v e s t e r , however, f r u i t r e m o v a l r e s u l t s from a p p l i c a t i o n o f a t e n s i l e f o r c e on t h e f r u i t . From the above t e s t i t appears t h a t f r u i t stem s t r e n g t h may l i m i t t h e e f f e c t i v e n e s s o f a m e c h a n i c a l h a r v e s t e r i n W i l l a m e t t e r a s p b e r r i e s . F r u i t C o l o r S e l e c t i v e h a r v e s t i n g o f r a s p b e r r i e s by hand i s based on f r u i t c o l o r . The human eye d i s t i n g u i s h e s between immature, mature and overmature f r u i t on the b a s i s o f c o l o r d i f f e r e n c e s . Measurement o f the s u r f a c e c o l o r o f r a s p b e r r i e s was, t h e r e f o r e , c o n d u c t e d i n an attempt t o d e t e r m i n e t h e r e l a t i o n s h i p between c o l o r and o t h e r f r u i t p r o p e r t i e s . An H i t a c h i P e r k i n - E l m e r model 139 UV-VIS s p e c t r o p h o t o -meter w i t h d i f f u s e r e f l e c t a n c e a t tachment was used f o r measuring f r u i t c o l o r . S i n c e c o l o r measurement i s a d e s t r u c t i v e t e s t w i t h t h i s i n s t r u m e n t ( c r u s h e d sample p l a c e d i n a g l a s s c e l l ) t h e s p e c t r o p h o t o m e t e r was m o d i f i e d t o n o n - d e s t r u c t i v e l y measure the e x t e r n a l c o l o r o f r a s p b e r r y f r u i t . A F i b r o x , n o n - c o h e r e n t , f i b r e o p t i c l i g h t p i p e , 4 5.7 cm l o n g x 6.2 mm d i a m e t e r , was used t o t r a n s m i t r e f l e c t e d l i g h t from t h e f r u i t t o t h e i n t e g r a t i n g sphere on t h e s p e c t r o p h o t o m e t e r . A 15 power m i c r o s c o p e eye-p i e c e was a t t a c h e d t o the i n t e g r a t i n g sphere i n p l a c e o f t h e sample h o l d e r ( f i g u r e 23) w i t h t h e end o f t h e l i g h t p i p e i n s e r t e d i n t o t h e e y e p i e c e tube a t a d i s t a n c e so t h a t the cone o f l i g h t emerging from t h e l i g h t p i p e c o m p l e t e l y f i l l e d t h e l e n s viewed by t h e i n t e g r a t i n g s p h e r e . (The a p e r t u r e a n g l e o f t h e l i g h t p i p e was 33°). I n d i v i d u a l f r u i t were p l a c e d u p r i g h t on.a 1.5 i n c h d i a m e t e r t u r n t a b l e ( f i g u r e 24) c o a t e d w i t h b l a c k s i l i c o n c a r b i d e paper >(Behr-Manning No. 2204 t u f b a k d u r i t e p a p e r ) . The o u t e r end o f t h e l i g h t p i p e was p l a c e d 1.5 i n c h e s above th e s u r f a c e o f the t u r n t a b l e . O r i g i n a l l y , t h e i n t e r n a l monochromatic l i g h t s o u r c e i n t h e s p e c t r o p h o t o m e t e r was used t o i l l u m i n a t e t h e f r u i t , t h r o u g h t h e l i g h t p i p e . That p o r t i o n o f t h e l i g h t w hich was r e f l e c t e d from t h e f r u i t and was i n t e r c e p t e d by t h e o u t e r end o f t h e l i g h t p i p e , r e t u r n e d t h r o u g h t h e p i p e t o t h e i n t e g r a t i n g s p h e r e . Even though t h e i n t e r n a l l i g h t s o u r c e was a d j u s t e d t o 5200 nm, t h e wave l e n g t h most r e a d i l y t r a n s m i t t e d by t h e l i g h t p i p e * s e n s i t i v i t y o f t h e s p e c t r o p h o t o m e t e r was t o o low t o s a t i s f a c t o r i l y d i s t i n g u i s h c o l o r d i f f e r e n c e s . A 17 w a t t e x t e r n a l w h i t e l i g h t s o u r c e ( f i g u r e 24) was t h e r e f o r e d i r e c t e d o n t o th e f r u i t by means o f an i n c l i n e d m i r r o r . W i t h t h i s - 50 -F i g u r e 2 3 S p ectrophotometer F i g u r e 24 T u r n t a b l e and e x t e r -m o d i f i c a t i o n n a l l i g h t s o u r c e m o d i f i c a t i o n , c o l o r d i f f e r e n c e s were d i s c e r n i b l e . C a l i b r a t i o n o f the s p e c t r o p h o t o m e t e r was by means o f a s t a n d a r d w h i t e powder c e l l and the b l a c k s u r f a c e on the t u r n t a b l e . The s p e c t r o p h o t o -meter was a d j u s t e d f o r a r e a d i n g o f 100 p e r c e n t r e f l e c t a n c e w i t h t h e w h i t e powder c e l l r o t a t e d t o i n t e r c e p t the l i g h t from t h e i n t e r n a l s o u r c e and w i t h no f r u i t on t h e t u r n t a b l e , a p r o c e d u r e s i m i l a r t o t h e s t a n d a r d c a l i b r a t i o n method f o r t h i s s p e c t r o -photometer. ^ C a l i b r a t i o n and c o l o r measurements were conducted i n a darkroom. By r o t a t i n g t h e t u r n t a b l e , b oth maximum and minimum r e f l e c t a n c e r e a d i n g s were t a k e n f o r each f r u i t . The complete i n s t r u m e n t a t i o n f o r measuring c o l o r i s shown i n f i g u r e 25. C o l o r i n d e x was d e f i n e d as t h e mean o f the maximum and minimum r e f l e c t a n c e r e a d i n g s f o r each f r u i t and ranged from 8 5 - 51 -F i g u r e 25 Complete i n s t r u m e n t a t i o n f o r measuring e x t e r n a l c o l o r o f r a s p b e r r y f r u i t -•Color Index F i g u r e 26 V a r i a t i o n i n f r u i t c o l o r as de t e r m i n e d by r e f l e c t a n c e measurements - 52 -f o r overmature f r u i t , s u i t a b l e o n l y f o r p r o c e s s i n g , t o 105 f o r f i r m f r u i t , s u i t a b l e f o r t h e f r e s h market ( f i g u r e 2 6 ) . As i s d i s c u s s e d l a t e r , c o r r e l a t i o n s among c o l o r and o t h e r f r u i t p r o p e r t i e s ( T a b l e s IX and X) were h i g h l y s i g n i f i c a n t . B r u i s i n g C h a r a c t e r i s t i c s o f Ra s p b e r r y F r u i t Drop t e s t s were c o n d u c t e d t o d e t e r m i n e t h e r e s i s t a n c e o f r a s p b e r r y f r u i t t o m e c h a n i c a l damage. F r u i t , w i t h stem and. c o r e a t t a c h e d , were dropped onto a smooth r i g i d F o r m i c a s u r f a c e from p r e d e t e r m i n e d h e i g h t s . The stem p r e v e n t e d t h e f r u i t from t u m b l i n g as i t f e l l , making i t p o s s i b l e t o d e t e r m i n e t h e p o i n t o f i m p a c t . B r u i s i n g damage was a s s e s s e d v i s u a l l y t h i r t y m i n u t e s a f t e r t h e drop. C o l o r i n d e x was used as a measure o f f r u i t m a t u r i t y i n o r d e r t o a s s e s s t h e b r u i s i n g c h a r a c t e r i s t i c s o f f r u i t a t d i f f e r e n t s t a g e s o f m a t u r i t y . The e x t e n t o f b r u i s i n g was d e t e r m i n e d by mea s u r i n g the d e p t h and d i a m e t e r o f each b r u i s e . R e s u l t s o f drop t e s t s a r e r e p o r t e d i n T a b l e V. Assuming damage t o one d r u p e l e t as an a c c e p t a b l e l e v e l o f b r u i s i n g , t h e maximum f r e e f a l l h e i g h t f o r a f r u i t o f c o l o r i n d e x 100 was 8 cm whereas f o r a f r u i t o f c o l o r i n d e x 90, i t was 4 cm. The maximum impact energy (e^) whi c h may be absorbed by a f r u i t o f c o l o r i n d e x 90 may be e s t i m a t e d as (4) (5) = 20 gm cm B a s i n g t h e r e s u l t on a mean f r u i t w eight o f 3.52 - 0.97 gm t h e a l l o w a b l e f r e e f a l l h e i g h t (h ) from e q u a t i o n [ 1 2 ] i s ct 20/(3.52+ 0.97) = 4.5 cm S i m i l a r l y , from e q u a t i o n [ 1 3 ] , t h e a l l o w a b l e impact v e l o c i t y (V f l) i s - 53 -( 2 ( 2 0 ) ( 9 8 1 ) / ( 3 . 5 2 + 0.97)) 1/2 Q 1 1 . 1 = 94 cm/sec 1 = 187 f t / m i n TABLE V RESULTS OF DROP TESTS H e i g h t o f Drop (cm) F r u i t Weight, i n c l u d i n g Stem and Core (gm) C o l o r Index R e s u l t 8 5.0 100 One d r u p e l e t b r u i s e d 8 5.0 90 Three d r u p e l e t s b r u i s e d 15 5.2 100 ' Three d r u p e l e t s b r u i s e d 15 5.9 90 B r u i s e d i a m e t e r 6 mm 30 5.0 100 B r u i s e d i a m e t e r 12 mm 3 mm deep. 30 5.0 90 B r u i s e d i a m e t e r 15 mm 6 mm deep. 75 4.5 100 B r u i s e d i a m e t e r 15 mm 6 mm deep. 75 5.6 90 Complete f r u i t b r u i s e d . F o r c e - D e f o r m a t i o n C h a r a c t e r i s t i c s o f R a s p b e r r y F r u i t As was p r e v i o u s l y m e n t i o n e d , q u a l i t y o f r a s p b e r r y f r u i t i s a t p r e s e n t p o o r l y d e f i n e d . F o r c e - d e f o r m a t i o n c h a r a c t e r i s t i c s o f r a s p b e r r y f r u i t were i n v e s t i g a t e d i n o r d e r t o more a c c u r a t e l y d e f i n e q u a l i t y and t o r e l a t e f r u i t p r o p e r t i e s t o f r u i t c o l o r and f r u i t r e t e n t i o n f o r c e . F o r c e - d e f o r m a t i o n c u r v e s were o b t a i n e d by p l a c i n g t h e f r u i t u p r i g h t between two f l a t p l a t e s on an I n s t r o n t e s t i n g machine ( f i g u r e 27) and a p p l y i n g a c o m p r e s s i v e l o a d a t a 1 V and h , as d e t e r m i n e d above, a r e based on a f r u i t w eight o f Si cl \" t h e mean p l u s one s t a n d a r d d e v i a t i o n o f the f r u i t w e i g h t d i s -t r i b u t i o n . E i g h t y f o u r p e r c e n t o f the i n d i v i d u a l measures d e f i n i n g a normal d i s t r i b u t i o n have v a l u e s l e s s t h a n (u + a) whereas 97.5 p e r c e n t have v a l u e s l e s s t h a n (u + 2 a ) . - 54 -F i g u r e 2 7 Method o f l o a d i n g f r u i t i n I n s t r o n machine Fruit Deformation (millimeters) F i g u r e 28 T y p i c a l f o r c e - d e f o r m a t i o n c u r v e f o r r a s p b e r r y f r u i t s u b j e c t e d t o f l a t - p l a t e l o a d i n g a t 2 cm/min. - 55 -r a t e o f two cm/min. No a t t e m p t was made t o d e t e r m i n e t h e t i m e dependent p r o p e r t i e s o f t h e f r u i t ; o n l y one r a t e o f l o a d i n g was used. A t y p i c a l f o r c e - d e f o r m a t i o n c u r v e f o r r a s p b e r r y f r u i t i s shown i n f i g u r e 28. Three c h a r a c t e r i s t i c m o d u l i were o b t a i n e d from each c u r v e : t h e a n g l e modulus ( t h e a n g l e between t h e l o w e r l i n e a r p o r t i o n o f t h e c u r v e and t h e \" d e f o r m a t i o n a x i s ) , t h e t a n g e n t modulus ( t h e t a n g e n t o f t h e above a n g l e ) and t h e l i n e a r l i m i t ( t h e minimum l o a d a t w h i c h t h e c u r v e became n o n - l i n e a r ) . C o r r e l a t i o n s among f o r c e - d e f o r m a t i o n c h a r a c t e r i s t i c s and o t h e r f r u i t p r o p e r t i e s , w h i c h a r e p r e s e n t e d i n T a b l e V I I I , a r e d i s -c u s s e d l a t e r . Based on t h e u n i t s o f measurement which d e f i n e d t h e f o r c e - d e f o r m a t i o n c u r v e s , t h e r e l a t i o n s h i p between compres-s i v e l o a d and f r u i t d e f o r m a t i o n was P = d (20Y) [25] c c where P c . = c o m p r e s s i v e l o a d , gm d = f r u i t d e f o r m a t i o n , mm c ' Y = t a n g e n t modulus ( T a b l e V I I I ) F o r t h e s e u n i t s o f measurement, K ( e q u a t i o n [18]) has a v a l u e o f 20y. F r u i t R i g i d i t y I n an a t t e m p t t o measure f r u i t q u a l i t y , an a p p a r a t u s s i m i l a r t o t h a t d e v e l o p e d by Nybom and d e s c r i b e d i n r e f e r e n c e (24) was used. I n d i v i d u a l r a s p b e r r i e s were p l a c e d u p r i g h t between the diaphragms o f two earphones ( f i g u r e 29). The upper earphone e x e r t e d a c o m p r e s s i v e f o r c e o f t e n grams on t h e f r u i t w h i l e t h e l o w e r earphone was e x c i t e d a t a f r e q u e n c y o f 250 Hz by a s i g n a l - 56 -g e n e r a t o r . V i b r a t i o n s t r a n s m i t t e d t h r o u g h the f r u i t t o the upper earphone g e n e r a t e d an a l t e r n a t i n g c u r r e n t which was a m p l i f i e d by an A-C a m p l i f i e r and r e a d on an ammeter. The ammeter r e a d i n g was d e f i n e d as f r u i t r i g i d i t y . C o r r e l a t i o n s among r i g i d i t y and o t h e r f r u i t p r o p e r t i e s a r e p r e s e n t e d i n T a b l e V I I I and are d i s c u s s e d l a t e r . As i s shown i n Table VI r i g i d i t y r e a d i n g s were s i g n i f i -c a n t l y c o r r e l a t e d w i t h f r u i t d i m e n s i o n s a t P < 0.01. - 57 -TABLE VI SIMPLE CORRELATIONS AMONG RIGIDITY AND FRUIT DIMENSIONS F r u i t F r u i t Maximum Minimum Weight Length F r u i t F r u i t D i a m e t e r Diameter R i g i d i t y 1.00 F r u i t Weight -0.42 1.00 F r u i t L e n g t h -0.44 0.79 1.00 Maximum F r u i t D i a m e t e r -0.30 0.72 0.62 1.00 Minimum F r u i t D i a m e t e r -0.22 0.80 0.63 0.72 1.00 n = 144 r 0 . 05 = 0.16 r 0 . 0 1 = ° ' 2 1 Sugar Content o f F r u i t I n a f u r t h e r a t t e m p t t o r e l a t e f r u i t p r o p e r t i e s , s u g a r con-t e n t was measured on 141 randomly s e l e c t e d samples d u r i n g two days a t t h e b e g i n n i n g o f t h e 1968 h a r v e s t . Sugar c o n t e n t was d e t e r m i n e d i n the f i e l d w i t h a Z e i s s model 0/8 5 hand s u g a r r e f r a c t o m e t e r , w h i c h measures s u g a r on t h e b a s i s o f d i f f e r e n c e s i n i n d i c e s o f r e f r a c t i o n o f s u g a r s o l u t i o n s . S i m p l e c o r r e l a t i o n s among f r u i t r e t e n t i o n f o r c e , f r u i t w e i g h t and suga r c o n t e n t a r e p r e s e n t e d i n T a b l e V I I . S i n c e s u g a r c o n t e n t measurement was a d e s t r u c t i v e t e s t , c o r r e l a t i o n s between s u g a r c o n t e n t and f o r c e -d e f o r m a t i o n c h a r a c t e r i s t i c s were not o b t a i n e d . As can be seen from the t a b l e , t h e s i m p l e c o r r e l a t i o n o f f r u i t r e t e n t i o n f o r c e on f r u i t s ugar c o n t e n t was not s i g n i f i c a n t a t P 5 0.05. - 58 -TABLE V I I SIMPLE CORRELATIONS AMONG FRUIT RETENTION FORCE, FRUIT WEIGHT AND FRUIT SUGAR CONTENT Mean F r u i t R e t e n t i o n F o r c e (gm) F r u i t Weight (gm) F r u i t Sugar Content ( p e r c e n t ) 303 .0 5.1 S t a n d a r d D e v i a t i o n F r u i t R e t e n t i o n F r u i t 10. 2 n = 141 152.0 0.75 1.75 r 0 . 05 Force 1.00 0.12 0.14 = 0.16 1.00 0. 21 r 0 . 0 1 = ° ' 2 1 F r u i t Weight Sugar Content 1. 00 Comparison o f F r u i t P r o p e r t i e s i n an Attempt t o D e f i n e F r u i t ; Q u a l i t y I n hand g r a d i n g r a s p b e r r i e s , t h e g r a d e r bases h i s d e c i s i o n p r i m a r i l y on f r u i t c o l o r and on f i r m n e s s o f f r u i t as d e t e r m i n e d by f e e l i n g t h e f r u i t w i t h h i s f i n g e r s . Both o f t h e s e parameters i n f l u e n c e t h e a c c e p t i b i l i t y o f the f r u i t a t t h e consumer l e v e l . An immature f r u i t i s o f l i g h t c o l o r and f e e l s f i r m between the f i n g e r s w h i l e an overmature f r u i t i s o f dark c o l o r and i s s o f t . S i n c e a m e c h a n i c a l h a r v e s t e r must s e l e c t i v e l y h a r v e s t f r u i t o f a c c e p t a b l e q u a l i t y , t h e r e l a t i o n s h i p between f r u i t p r o p e r t i e s was s t u d i e d i n o r d e r t o o b t a i n a par a m e t e r w h i c h c o u l d be used f o r m e c h a n i c a l f r u i t s e l e c t i o n . T a b l e V I I I p r e s e n t s s i m p l e c o r r e l a t i o n s among f r u i t - 59 -r e t e n t i o n f o r c e , F/W, r i g i d i t y and f o r c e - d e f o r m a t i o n m o d u l i f o r a random sample o f 90 f r u i t c o l l e c t e d on f i v e d i f f e r e n t days d u r i n g t h e 1968 h a r v e s t season. As can be s e e n , f r u i t r e t e n t i o n f o r c e and F/W a r e b o t h s i g n i f i c a n t l y c o r r e l a t e d w i t h f o r c e -d e f o r m a t i o n c h a r a c t e r i s t i c s o f the f r u i t . The h i g h e s t c o r r e l a -t i o n e x i s t s w i t h t h e t a n g e n t modulus. The t a n g e n t modulus may be c o n s i d e r e d as an e l a s t i c modulus i n d i c a t i n g how f i r m l y t h e i n d i v i d u a l d r u p e l e t s a r e h e l d t o g e t h e r and hence i s a good i n d i c a t o r o f f r u i t f i r m n e s s as measured by hand. As can a l s o be seen from t h e t a b l e , r i g i d i t y as measured by t r a n s m i s s i o n o f v i b r a t i o n i s p o o r l y c o r r e l a t e d w i t h f r u i t r e t e n t i o n f o r c e o r o t h e r f r u i t p r o p e r t i e s . TABLE V I I I SIMPLE CORRELATIONS AMONG FRUIT RETENTION FORCE, F/W, RIGIDITY AND FORCE-DEFORMATION MODULI F r u i t R e t e n t i o n F o r c e (gm) R i g i d i t y -F/W (ampxlO -\" 3) A n g l e Modulus ( d e g r e e s ) Tangent Modulus L i n e a r L i m i t (gm) Mean 254.0 82.7 440.0 50.0 1. 32 189.0 S t a n d a r d D e v i a t i o n 146.0 65.0 190.0 12.2 0. 54 71.0 F r u i t R e t e n t i o n F o r c e 1.00 F/W 0.88 1.00 R i g i d i t y 0.15 0.23 1.00 A n g l e Modulus 0.66 0.57 0.17 1.00 Tangent Modulus 0.68 0.61 0.15 0.96 1.00 L i n e a r L i m i t 0.59 0.49 0.03 0.76 0.81 1.00 n = 90 r 0 . 0 5 = 0.22 r 0 . 0 1 = 0.28 - 60 -T a b l e s IX and X p r e s e n t s i m p l e c o r r e l a t i o n s among f r u i t c o l o r i n d e x , f r u i t r e t e n t i o n f o r c e , F/W, r i g i d i t y and f o r c e -d e f o r m a t i o n m o d u l i f o r 144 random samples p i c k e d on t h e f i r s t day and on the f i f t e e n t h day o f the 1968 h a r v e s t season. As can be seen from t h e s e t a b l e s , s i g n i f i c a n t c o r r e l a t i o n s e x i s t among c o l o r i n d e x , f r u i t r e t e n t i o n f o r c e , F/W and f o r c e - d e f o r m a t i o n m o d u l i f o r b o t h days o f measurement. The s i m p l e l i n e a r r e g r e s -s i o n s o f f r u i t r e t e n t i o n f o r c e and F/W on c o l o r i n d e x f o r the f i r s t day o f t h e h a r v e s t season were F = 1335.6+17.7C, r 2 = 0 . 2 9 , n = 144, S y = 133.1 [26] F/W = -205.2+3.2C, r 2 =0.08, n = 144, S y = 53.3 [27] f o r t h e range 84.5 < C < 109.0 where F = f r u i t r e t e n t i o n f o r c e , g r a m s F/W = f r u i t r e t e n t i o n f o r c e / f r u i t w e i g h t C = f r u i t c o l o r i n d e x S i m i l a r l y , f o r t h e f i f t e e n t h day o f t h e h a r v e s t season t h e r e g r e s s i o n e q u a t i o n s were F = 1728.7+21.7C, r 2 = 0 . 2 8 , n = 144, S y = 113.4 [ 2 8 ] F/W = 488.0 + 6.2C, r 2 = 0 . 2 6 , n = 144, S y = 34.1 [29] f o r t h e range 84.0 < C < 100.0 The s i m p l e l i n e a r r e g r e s s i o n s o f i n d i v i d u a l f o r c e - d e f o r m a t i o n m o d u l i on c o l o r i n d e x were a l s o o b t a i n e d . Comparison o f s i m i l a r r e g r e s s i o n e q u a t i o n s , f o r t h e f i r s t and f i f t e e n t h day o f the h a r v e s t s e a s o n , u s i n g t h e a n a l y s i s o f c o v a r i a n c e (33) r e v e a l e d t h a t s i m i l a r r e g r e s s i o n s were homogeneous w i t h r e s p e c t t o r e s i d u a l v a r i a n c e and d i d not have s i g n i f i c a n t l y d i f f e r e n t s l o p e s . L e v e l s f o r t h e two days o f measurement were, however, s i g n i f i c a n t l y d i f f e r e n t . F o r example, t h e s i m p l e l i n e a r r e g r e s s i o n s o f t a n g e n t modulus on c o l o r i n d e x f o r t h e f i r s t and f i f t e e n t h day, r e s p e c t i v e l y , were Y = -5.16+0.07C, r 2 = 0.33, n = 144, S y = 0.51 [30] f o r t h e range 84.5 [33] where {Z^} = t h e column m a t r i x f o r t h e f i r s t mode [C] = the f l e x i b i l i t y m a t r i x ( T a b l e X I ) [ vnu]= t h e d i a g o n a l mass m a t r i x ( T a b l e X I I ) [D] = [C] [ v r r u ] = t h e dynamic m a t r i x o)^ = t h e f u n d a m e n t a l ( f i r s t ) n a t u r a l f r e q u e n c y o f th e cane 1 These d a t a a p p l y t o t h e same cane f o r which t h e f l e x i b i l i t y m a t r i x was p r e s e n t e d i n T a b l e X I . Cane 1 Cane 2 1 r First Mode -o Q. E < -o CD N ~o E o Z -1 1 2 3 4 A distance above soil surface (feet) CO - 1 L F i g u r e 32 C a l c u l a t e d modes o f v i b r a t i o n and c o r r e s p o n d i n g n a t u r a l f r e q u e n c i e s f o r two r a s p b e r r y canes. - 69 -The l a s t column o f t h e dynamic m a t r i x was n o r m a l i z e d and used as an i n i t i a l a p p r o x i m a t i o n f o r t h e mode shape. A p p l i c a t i o n o f t h e i t e r a t i v e p r o c e d u r e shown i n e q u a t i o n [33] r e s u l t e d i n convergence t o the f i r s t p r i n c i p l e mode and y i e l d e d t h e f u n d a -m e n t a l f r e q u e n c y , co^. F o r d e t e r m i n a t i o n o f t h e second mode and the second n a t u r a l f r e q u e n c y , a sweeping m a t r i x , d e v o i d o f t h e f i r s t mode, was used i n t h e i t e r a t i v e p r o c e d u r e . {Z 2> = t o 2 2 [ D ] [ S 1 ] {Z 2> [34] where {Z,,} = t h e column m a t r i x f o r t h e second mode [S^ ] = t h e sweeping m a t r i x to 2 = t h e second n a t u r a l f r e q u e n c y o f t h e cane The f i r s t two modes and c o r r e s p o n d i n g r e s o n a n t f r e q u e n c i e s f o r t h e two r a s p b e r r y canes a r e p r e s e n t e d i n f i g u r e 32. The c a l c u l a t e d r e s o n a n t f r e q u e n c i e s o f t h e two canes were 185 and 218 c y c l e s p e r minute f o r t h e f i r s t mode and 786 and 1032 c y l e s p e r minute f o r t h e second mode. The i n c l u s i o n o f f r u i t and l i m b mass and damping would r e d u c e t h e s e f r e q u e n c i e s c o n s i d e r a b l y . Due t o t h e s i m p l y i n g a s s u m p t i o n s used i n t h e s e d e t e r m i n a t i o n s , the r e s u l t i n g v a l u e s a r e not i n d i c a t i v e o f t h e a c t u a l dynamic r e s p o n s e o f t h e complete p l a n t . The r e s u l t s a r e , however, u s e f u l i n d e s i g n i n g a h a r v e s t i n g machine. The l a r g e d i f f e r e n c e s o b s e r v e d between t h e two canes i n d i c a t e t h a t a t t e m p t i n g t o d e s i g n a h a r v e s t i n g machine w h i c h o p e r a t e s a t a r e s o n a n t f r e q u e n c y o f the p l a n t system i s i m p r a c t i c a l . F u r t h e r m o r e , a p p l i c a t i o n o f base m o t i o n t o o n l y one p a r t o f the canes ( f i g u r e 10) i s a l s o i m p r a c t i c a l s i n c e t h e r e s u l t i n g i n e r t i a l f o r c e d e v e l o p e d i n t h e f r u i t i n g p o r t i o n s w i l l be v a r i a b l e , depending upon t h e p r o p e r t i e s o f t h e i n d i v i d u a l canes. E l a s t i c Modulus o f R a s p b e r r y Canes The e l a s t i c modulus o f the two canes s t u d i e d i n the p r e v i o u s s e c t i o n was e s t i m a t e d by b o t h an energy method and by a n u m e r i c a l s o l u t i o n o f the E u l e r e q u a t i o n f o r l a r g e d e f l e c t i o n s o f t a p e r e d beams. The energy s o l u t i o n was based on R a y l e i g h ' s method (36) f o r d e t e r m i n a t i o n o f t h e f u n damental f r e q u e n c y o f a c o n t i n u o u s system. The fundamental f r e q u e n c y as o b t a i n e d from the m a t r i x i t e r a t i o n p r o c e d u r e was s u b s t i t u t e d i n t o R a y l e i g h ' s f o r m u l a t i o n and t h e r e s u l t i n g e q u a t i o n was s o l v e d f o r the e l a s t i c modulus. E = (UK) 2 [/ Lm(x) Z 2 dx / / L I ( x ) ( ^ - | ) 2 dx] [35] o ' o M x ' where I ( x ) = moment o f i n e r t i a o f the cane c r o s s s e c t i o n p e r u n i t o f l e n g t h L = t o t a l l e n g t h o f t h e cane Z = mode shape m(x)= mass o f the cane p e r u n i t o f l e n g t h = f u n d a m e n t a l f r e q u e n c y o f t h e cane The canes were c o n s i d e r e d as t a p e r e d c a n t i l e v e r beams o f c i r c u l a r c r o s s s e c t i o n . I ( x ) and m(x) were d e t e r m i n e d by p l o t t i n g the v a l u e s o f cane d i a m e t e r and cane mass f o r each o f the e i g h t s t a t i o n s used i n d e t e r m i n i n g the f l e x i b i l i t y m a t r i x 2 and f i t t i n g s t r a i g h t l i n e s . A p a r a b o l i c mode shape, Z = C^ x , s a t i s f y i n g t h e boundary c o n d i t i o n s f o r a c a n t i l e v e r beam, was chosen. The r e s u l t i n g e s t i m a t e s o f e l a s t i c modulus f o r the two 2 canes shown i n f i g u r e 32 were 295,000 l b / i n f o r cane 1 and 469,000 l b / i n 2 f o r cane 2. - .71 -A second e s t i m a t e o f the e l a s t i c modulus was o b t a i n e d by use o f n u m e r i c a l s o l u t i o n s o f the E u l e r e q u a t i o n f o r l a r g e d e f l e c t i o n s o f t r u n c a t e d cones w i t h c o n c e n t r a t e d end l o a d s , as p r e s e n t e d by D i e n e r e t a l ( l i ) # The t a b u l a t e d s o l u t i o n s , which were used by t h e s e a u t h o r s i n s t u d y i n g t h e d e f l e c t i o n o f a p p l e l i m b s , a r e o f t h e form o where E = e l a s t i c modulus I = moment o f i n e r t i a o f c r o s s s e c t i o n a t r o o t o f l i m b L = l i m b l e n g t h P A = c o n c e n t r a t e d l o a d a p p l i e d a t l i m b t i p q = P L 2 / E . I M a / o c = t a p e r o f l i m b = t i p r a d i u s / r o o t r a d i u s y = d e f l e c t i o n o f l i m b t i p S u b s t i t u t i n g a p p r o p r i a t e v a l u e s o f I , P , L, y and c f o r O ' cl t h e two r a s p b e r r y c a n e s , i n t o t h e t a b u l a t e d s o l u t i o n s r e s u l t e d 2 i n e s t i m a t e s o f e l a s t i c modulus o f 255,000 l b s / i n and 463,000 2 l b s / i n f o r canes 1 and 2 r e s p e c t i v e l y . C o n t r o l o f P h y s i c a l P r o p e r t i e s - Growth R e g u l a t o r s The f o l l o w i n g d i s c u s s i o n does n ot d i r e c t l y p e r t a i n t o d e s i g n o f a m e c h a n i c a l h a r v e s t e r but i s i n c l u d e d s i n c e i t may s i g n i f i c a n t l y a f f e c t t h e performance o f m e c h a n i c a l h a r v e s t i n g systems f o r r a s p b e r r i e s . S i n c e t h e h i g h r a t i o o f f r u i t r e t e n -t i o n f o r c e t o f r u i t stem s t r e n g t h may s e r i o u s l y l i m i t t h e p i c k i n g e f f i c i e n c y o f a m e c h a n i c a l h a r v e s t e r , an at t e m p t was - 72 -made t o reduce f r u i t r e t e n t i o n f o r c e t h r o u g h the use o f c h e m i c a l growth r e g u l a t o r s . U n r a t h and Kenworthy (2 3) s u c c e s s f u l l y used growth r e g u l a t o r s t o reduce t h e f r u i t r e t e n t i o n f o r c e o f c h e r r i e s . A s i m i l a r t e c h n i q u e was a p p l i e d t o r a s p b e r r i e s i n an att e m p t t o improve the s u i t a b i l i t y o f t h e p l a n t s t o m e c h a n i c a l h a r v e s t i n g . S i n c e no p u b l i s h e d r e s u l t s on the use o f growth r e g u l a t o r s on r a s p b e r r i e s c o u l d be o b t a i n e d , growth r e g u l a t o r s were s e l e c t e d on the b a s i s o f t h e i r e f f e c t on o t h e r f r u i t . A randomized b l o c k c o n s i s t i n g o f f o u r t e e n p l o t s ( f i g u r e 33) each h a v i n g t e n p l a n t s , was used f o r t h e growth r e g u l a t o r t r i a l s . The s e l e c t e d growth r e g u l a t o r s were s u c c i n i c a c i d 2 , 2 - d i m e t h y l -h y d r a z i d e ( A l a r ) and a m i x t u r e o f e q u a l p a r t s o f 2,4, 5 - t r i c h l o r o p h e n o x y p r o p i o n i c a c i d (2,4,5-TP) and n a p h t h e l e n e a c e t i c a c i d (NAA). Three c o n c e n t r a t i o n s o f each o f the growth r e g u l a t o r s were a p p l i e d t o i n d i v i d u a l p l o t s a t two d i f f e r e n t a p p l i c a t i o n d a t e s as shown i n T a b l e X I I I . Growth r e g u l a t o r s were a p p l i e d u s i n g a s e m i - c i r c u l a r s p r a y boom ( f i g u r e 34) w i t h f o u r No. 650067 T - J e t s p r a y n o z z l e s spaced t o a p p l y r e l a t i v e l y u n i f o r m c o v e r a g e on t h e f r u i t b e a r i n g p o r t i o n o f t h e p l a n t s . Two such booms were used t o a v o i d p o s s i b l e m i x i n g o f growth r e g u l a t o r s . The s p r a y s o l u t i o n was p l a c e d i n t h e l i q u i d t a n k on the boom end ( f i g u r e 34) and a i r a t 40 p s i g was a p p l i e d t o t h e t a n k w i t h a p o r t a b l e a i r compressor. The r e s u l t i n g r a t e o f d i s c h a r g e o f each s p r a y boom was 1000 cc/m i n . The c o n c e n t r a t i o n o f A l a r p l a c e d i n t h e s p r a y t a n k was 1000 ppm w h i l e the c o n c e n t r a t i o n o f 2,4,5-TP+NAA was 20 ppm. I n o r d e r t o o b t a i n the low c o n c e n t r a t i o n s - 73 -F i g u r e 3 3 Randomized p l o t s f o r growth r e g u l a t o r t r i a l s F i g u r e 34 Spray boom f o r a p p l y i n g growth r e g u l a t o r s ( T a b l e X I I I ) 250 cc o f t h e s o l u t i o n was a p p l i e d t o t h e s e l e c t e d 10 p l a n t p l o t , w h i l e t o o b t a i n t h e medium c o n c e n t r a t i o n s , 500 cc was a p p l i e d and f o r t h e h i g h c o n c e n t r a t i o n s , 1000 cc was a p p l i e d . T h i s was a c c o m p l i s h e d by making one f i f t e e n second pass o f the s p r a y boom o v e r a p l o t f o r low c o n c e n t r a t i o n s , two pas s e s (30 seconds) f o r i n t e r m e d i a t e c o n c e n t r a t i o n s , and f o u r p a s s e s (one minute) f o r h i g h c o n c e n t r a t i o n s . TABLE X I I I GROWTH REGULATOR TREATMENTS Treatment P l o t Number Growth C o n c e n t r a t i o n A p p l i c a t i o n Number (see F i g . 3 3 ) R e g u l a t o r (p.p.m.) Date 1 3 check 0 2 4 A l a r 1000 June 17 3 16 A l a r 2000 June 17 4 2 A l a r 4000 June 17 5 15 2,4,5-TP+NAA 20 June 17 6 6 2,4,5-TP+NAA 40 June 17 7 8 2,4,5-TP+NAA 80 June 17 8 7 check 0 9 11 A l a r 1000 June 28 10 1 A l a r 2000 June 28 11 13 A l a r 4000 June 28 12 9 2,4,5-TP+NAA 20 June 28 13 10 2,4,5-TP+NAA 40 June 28 14 14 2,4,5-TP+NAA 80 June 28 Three p l a n t s i n each p l o t were s e l e c t e d f o r c o m p a r a t i v e p u r p o s e s . On each o f f i v e days d u r i n g the h a r v e s t s e a s o n , t h r e e - 75 -f r u i t were p i c k e d a t random from each s e l e c t e d p l a n t i n each p l o t . F r u i t r e t e n t i o n f o r c e , f r u i t weight, f r u i t c o l o r , r i g i d -i t y and f o r c e - d e f o r m a t i o n c h a r a c t e r i s t i c s were determined f o r each f r u i t . A n a l y s i s o f v a r i a n c e t e s t s were conducted, comparing the measured v a r i a b l e s o f the growth r e g u l a t o r treatments. R e s u l t s o f the t e s t s i n d i c a t e d t h a t both types o f growth r e g u l a -t o r s s i g n i f i c a n t l y a f f e c t e d f r u i t r e t e n t i o n f o r c e , f r u i t c o l o r and f r u i t weight. The type o f growth r e g u l a t o r , i t s c o n c e n t r a t i o n and i t s time o f a p p l i c a t i o n a l l a f f e c t e d f r u i t r e t e n t i o n f o r c e . Furthermore, the e f f e c t was dependent upon time o f h a r v e s t . S i n c e f r u i t r e t e n t i o n f o r c e , f r u i t weight and F/W a l l i n f l u e n c e h a r v e s t e r d e s i g n , the e f f e c t o f growth r e g u l a t o r s on these parameters was i n v e s t i g a t e d more f u l l y . The simple r e g r e s s i o n s o f f r u i t r e t e n t i o n f o r c e on h a r v e s t time were d e t e r -mined (Table XIV) f o r each treatment. The a n a l y s i s o f c o v a r i a n c e (33) was used t o compare the r e g r e s s i o n f o r each growth r e g u l a t o r treatment t o the p o o l e d r e g r e s s i o n f o r treatments 1 and 8. T h i s a n a l y s i s compared homogeneity o f r e s i d u a l v a r i a n c e , s l o p e and l e v e l o f the two r e g r e s s i o n l i n e s i n o r d e r to f i n d s i g n i f i c a n t d i f f e r e n c e s . S i m i l a r comparisons were made f o r f r u i t weight (Table XV) and F/W (Table XVI). Tables XIV, XV, XVI are based on 90 o b s e r v a t i o n s f o r the check and 4 5 o b s e r v a t i o n s f o r each growth r e g u l a t o r treatment. The f i r s t column i n each t a b l e r e p r e s e n t s the treatment as shown i n T a b l e X I I I . The f o u r t h column i s the i n t e r c e p t and the f i f t h column i s the s l o p e o f the r e g r e s s i o n e q u a t i o n , Y = a + bT, where Y i s the dependent v a r i a b l e named i n the t i t l e o f the t a b l e . - 76 -The r e g r e s s i o n e q u a t i o n s a p p l y f o r the i n t e r v a l , 1 < T < 15, where T i s t i m e i n days and (T = 1) i s t h e f i r s t day o f h a r v e s t . The n i n t h , t e n t h and e l e v e n t h columns i n each t a b l e i n d i c a t e r e s u l t s o f t h e c o v a r i a n c e a n a l y s i s . In c a s e s where the homo-g e n e i t y o f r e s i d u a l v a r i a n c e show a s i g n i f i c a n t d i f f e r e n c e , t h e t e s t s f o r s l o p e and l e v e l a r e not v a l i d . The r e s u l t s o f the c o v a r i a n c e a n a l y s i s i n d i c a t e t h a t t h e use o f growth r e g u l a t o r s c o u l d s i g n i f i c a n t l y a f f e c t t h e p e r f o r -mance o f a m e c h a n i c a l h a r v e s t e r . F o r example, t r e a t m e n t s 3 and 14 s i g n i f i c a n t l y r e d u c e d f r u i t r e t e n t i o n f o r c e w h i l e t r e a t m e n t s 5, 11 and 14 s i g n i f i c a n t l y r e d u c e d F/W, f o r the e a r l y p a r t o f the h a r v e s t s e a s o n . S i n c e t h e h i g h e s t r a t i o o f f r u i t r e t e n t i o n f o r c e t o stem s t r e n g t h o c c u r s e a r l y i n t h e h a r v e s t s e a s o n , t h e s e t r e a t m e n t s c o u l d p o s s i b l y i n c r e a s e t h e p i c k i n g e f f i c i e n c y - o f a m e c h a n i c a l h a r v e s t e r d u r i n g t h e f i r s t p a r t o f the h a r v e s t . F u r t h e r t r i a l s a r e n e c e s s a r y b e f o r e any f i r m c o n c l u s i o n s may be drawn. TABLE XIV VARIATION OF FRUIT RETENTION FORCE WITH TIME AS AFFECTED BY GROWTH REGULATOR TREATMENTS Treatment Mean Standard (gm) Deviation S i g n i f i -cance of r S Significance of Covariance Anal-Homogeneity Slope T ' S 1 S I y of Variance e v e Check (pooled) 254 .0 146. 5 347. 7 -13.4 -.43 P< 0. 01 132. 9 — • -2 282 . 6 150. 8 382. 6 -14.3 -.45 P< 0.01 136. 3 NS NS P < 0. 25 3 280 .3 126. 7 287 . 3 - 1.0 -.04 NS1 128. 1 NS P < 0. 025 NS 4 389 .7 181. 1 452. 7 - 9.0 -.23 NS 178 . 1 NS NS P < 0. 005 5 289 . 2 132. 8 316. 8 - 4.0 -.14 NS 133. 0 NS P < 0. 10 P < 0. 25 6 315 .1 126. 3 392. 3 -11.0 -.41 P< 0.01 116. 3 P < 0. 25 NS P < 0. 01 ' 7 280 .6 122. 1 350. 6 -10.0 -.39 P< 0. 01 113. 8 P < 0. 25 NS NS -j i 9 287 .7 180. 1 386. 6 -14.1 -.37 P< 0.01 169. 1 NS NS P < 0. 25 10 266 .1 148. 1 310. 0 - 6.3 -.20 NS 146. 7 NS P < 0. 25 NS 11 288 .2 162. 2 344. 4 - 8.0 -.23 NS 159. 5 NS NS P < 0. 25 12 264 .9 143. 1 375. 8 -15.8 -.52 P< 0.01 123. 2 NS NS NS 13 3 39 .0 185. 9 445. 2 -15.2 -.39 P< 0.01 173. 4 NS NS P < 0. 005 14 292 .1 143. 1 273. 6 2.6 .09 NS 144. 2 NS P < 0. 005 P ^ 0. 25 1 NS indicates no s i g n i f i c a n t difference between the pooled check and the growth regulator treatment at P < 0.25 TABLE XV. VARIATION OF FRUIT WEIGHT WITH TIME AS AFFECTED BY GROWTH REGULATOR TREATMENTS Treatment Mean Sta n d a r d (gm) D e v i a t i o n S i g n i f i -cance o f r S S i g n i f i c a n c e o f C o v a r i a n c e A n a l -Homogeneity S l o p e L e v e l o f V a r i a n c e Check ( p o o l e d ) 3, .52 0. 97 3, .01 0, .07 .35 P < 0.01 0. 92 — --•-2 3, .92 1. 46 4, .10 -0, .03- .09 NS 1. 48 NS P < 0, .05 P < 0, .10 3 2. .76 1. 21 1, .80 0. .14 .54 P < 0.01 1. 03 NS P < 0, .10 P < 0, .005 4 4, .14 0. 83 4, .15 -0, .00- .01 NS 0. 84 NS P < 0, .05 P < 0. .005 5 3, .33 1. 16 3, .43 -0, .01- .06 NS 1. 18 NS P < 0. .05 NS i 6 4, .08 0. 76 4, .14 -0, .01- .05 NS 0. 77 P < 0.25 P < 0, .025 P < 0. ,005 « 7 3, .94 0. 95 4 , .57 -0, .09- .45 P < 0.01 0. 86 NS P < 0, ,005 P < 0, .025 ' 9 4, .64 0. 82 4, ,95 -0. , 04-.26 NS 0. 80 NS P < 0. .005 P < 0, .005 10 3, .98 0. 94 4. .16 -0, .02- .12 NS 0. 94 NS P < 0. ,01 P < 0. ,10 11 3. .85 0. 96 3. .83 0. ,00 .01 NS 0. 97 NS P < 0. .10 P < 0. ,10 12 4 . ,29 0. 89 4. , 33 -0. ,00- .03 NS 0. 90 NS P < 0. ,05 P < 0. ,005 13 4. ,32 1. 14 4. ,40 -0. ,01- .04 NS 1. 15 NS P < 0, ,05 P < 0. ,005 14 3. ,51 1. 41 3. ,85 -0. ,05- .16 NS 1. 41 NS P < 0. ,01 NS TABLE XVI F/W VARIATION WITH TIME AS AFFECTED BY GROWTH REGULATOR TREATMENTS Treatment Mean S t a n d a r d S i g n i f i - - S i g n i f i c a n c e o f C o v a r i a n c e A n a l -(gm) D e v i a t i o n . n c Homogeneity S l o p e ^ s : L S ^ 6 a b r r -S c ,,6 . J * L e v e l y o f V a r i a n c e Check ( p o o l e d ) 82.8 65.1 128.0 -6.5 -.47 P < 0.01 57.8 --•-2 93.5 105.1 143.4 -7.1 -.32 P < 0.05 100.6 NS NS NS 3 127.1 86.2 174.9 -6.8 -.38 P < 0.01 80.8 NS NS P < 0.005 4 98.0 50.8 117.4 -2.8 -.26 NS 49.6 P < 0. 25 P < 0. 10 P < 0.25 5 101.4 75.1 110.3 -1.3 -.08 NS 76.0 NS P < 0. 05 P < 0.25 1 6 80.8 36.3 96.8 -2.3 -.30 P < 0.05 35.1 P < 0.005 \" P < 0. 05 CD NS i 7 74.8 37.5 84.5 -1.4 -.17 NS 37.3 P < 0.005 P < 0. 025 NS 9 64.1 43.0 85.1 -3.0 -.33 P < 0.05 41.1 P < 0.005 P < 0. 10 P < 0.10 10 71.3 45.8 81.7 -1.5 -.15 NS 45.8 P < 0.05 P < 0. 025 NS 11 82.4 68 .0 94.7 -1.8 -.12 NS 68.3 NS P < 0. 10 NS 12 65.8 39.9 93.3 -3.9 -.47 P < 0.01 35.6 P < 0. 005 P < 0. 25 P < 0.10 13 82.7 47.4 108 .5 -3.7 -.37 P < 0.01 44.9 P < 0.05 P < 0. 25 NS 14 103.1 78.2 101.7 0.2 .01 NS 67.4 NS P < 0, 01 P < 0.10 MATHEMATICAL MODELS FOR THE TOOLS C o m p l e t i o n o f t h e T o o l A n a l y s e s I n t h i s c h a p t e r , t h e e l e m e n t a r y t o o l a n a l y s e s and t h e a n a l y s i s o f t h e p r o d u c t c h a r a c t e r i s t i c s a r e combined i n o r d e r t o o b t a i n m a t h e m a t i c a l models r e p r e s e n t i n g t h e performance o f each t o o l i n t h e p r o c e s s . The r e s u l t i n g e q u a t i o n s d e t e r m i n e t h e d e s i g n s p e c i f i c a t i o n s o f t h e i n d i v i d u a l t o o l s . T o o l f o r F e e d i n g and Cane O r i e n t a t i o n F i g u r e 11 i n d i c a t e s t h a t t h e t o t a l f r u i t b e a r i n g p o r t i o n o f th e r a s p b e r r y p l a n t i s l o c a t e d i n a 5 f o o t h e i g h t i n t e r v a l . S e l e c t i n g a v a l u e o f 45° f o r 8 ( f i g u r e 8) t h e maximum n e c e s s a r y f e e d r o l l l e n g t h i s 5 / s i n (45°) = 7.1 f t . S e l e c t i n g an e x t e r n a l f e e d r o l l d i a m e t e r o f 4 i n c h e s w i t h Q = 4 5°, f rom e q u a t i o n [ 3 ] t h e n e c e s s a r y r e l a t i o n s h i p between f e e d r o l l r o t a t i o n and f o r w a r d speed i s • • r i r = 118.8S [ 3 5] where n^ = f e e d r o l l speed, r e v o l u t i o n s p e r minute S = f o r w a r d speed o f h a r v e s t i n g machine, m i l e s p e r hour L e t t i n g x = L , i n e q u a t i o n [ 5 ] and s o l v i n g f o r P , t h e cl r e s u l t i n g e s t i m a t e o f t h e h o r i z o n t a l r e a c t i o n f o r c e between a s i n g l e cane and a f e e d r o l l i s P a = [3yEI c ( l - c ) 3 ] / [ ( l - 3 c + 3 c 2 - c 3 ) L 3 ] [ 3 6 ] c l U where L = t h e d i s t a n c e above t h e s o i l s u r f a c e a t whi c h t h e f e e d r o l l c o n t a c t s a cane, y = t h e h o r i z o n t a l cane d e f l e c t i o n a t the l o a d p o i n t , and E, I and c a r e as p r e v i o u s l y d e f i n e d . Due t o t h e - 80 -i n c l i n a t i o n o f t h e f e e d r o l l s , L, y and c depend upon t h e p o s i t i o n on t h e f e e d r o l l s a t which c o n t a c t w i t h each i n d i v i d u a l cane o c c u r s . The t o t a l r e a c t i o n f o r c e between t h e canes and f e e d r o l l s depends upon t h e t o t a l number o f canes i n c o n t a c t a t any i n s t a n t . Assuming a maximum number o f t e n canes and t e n s h o o t s p e r p l a n t and c o n s i d e r i n g a f e e d r o l l l e n g t h o f 7.1 f e e t and a p l a n t s p a c i n g o f 2.5 f e e t , a maximum o f 40 canes and s h o o t s w i l l be i n c o n t a c t w i t h t h e f e e d r o l l s . Assuming t h a t t h e f l e x u r a l p r o p e r t i e s o f t h e s h o o t s a r e s i m i l a r t o t h o s e o f t h e canes and n o t i n g t h a t one f e e d r o l l compresses o n l y h a l f o f t h e p l a n t , t h e t o t a l r e a c t i o n f o r c e on one f e e d r o l l w i l l r e s u l t from c o n t a c t w i t h 20 c a n e s . Assuming t h a t t h e 20 canes a r e e q u a l l y spaced a t 3 i n c h e s down the row, t h e h e i g h t ( i n c h e s ) above ground a t w h i c h a f e e d r o l l c o n t a c t s a cane ( f i g u r e 35) i s L = 6 + z [ 3 7 ] where z = t h e h o r i z o n t a l d i s t a n c e ( i n c h e s ) b e h i n d t h e f r o n t o f t h e f e e d r o l l a t w h i c h cane c o n t a c t o c c u r s Based on a p l a n t w i d t h o f 10 i n c h e s a t ground l e v e l and 60 i n c h e s a t t h e 5.5 f o o t h e i g h t , assuming a l l canes a r e so o r i e n t e d and f u r t h e r assuming t h a t i t i s d e s i r e d t o compress a l l p l a n t s t o an 8 i n c h w i d t h a t t h e 0.5 f o o t l e v e l and a 4 i n c h w i d t h a t t h e 5.5 f o o t l e v e l , i t can be shown by g e o m e t r i c a l i n t e r p r e t a t i o n ( f i g u r e 36) t h a t t h e h o r i z o n t a l cane d e f l e c t i o n ( i n c h e s ) i s y = 3.8 + 0.504z [38] where z i s as p r e v i o u s l y d e f i n e d . - 82 C U < U < cu ( J c o Feed roll centerline 1 2 3 4 Distance Behind Front of Feed Rolls (feet) F i g u r e 3 5 E s t i m a t i n g t h e p o i n t o f c o n t a c t between t h e canes and t h e f e e d r o l l s cu cu C U u o 5-D 3 3 CO o CO cu 5 < cu w c o 0 -3 .original « 101 oriental cane orientation (final cane 6 , 0 'orientation _2 _1 ° 0 ° 1 2 Distance Outward from Center of Row (feet) F i g u r e 36 E s t i m a t i n g the d e f l e c t i o n o f t h e canes by t h e f e e d r o l l s - 83 -Cane t a p e r , as d e f i n e d i n e q u a t i o n [ 5 ] , i s a l s o a f u n c t i o n o f t h e d i s t a n c e above ground a t wh i c h l o a d i n g o c c u r s . F i g u r e 37 shows a r a s p b e r r y cane r e p r e s e n t e d as a t a p e r e d c i r c u l a r c a n t i -l e v e r beam. The d i m e n s i o n s used i n t h i s f i g u r e a r e t h o s e o f t h e same cane as d e s c r i b e d i n T a b l e s XI and X I I and r e p r e s e n t t h e l a r g e s t e x p e c t e d s i z e o f r a s p b e r r y canes. By g e o m e t r i c a l i n t e r -p r e t a t i o n o f f i g u r e 37, cane t a p e r may be d e f i n e d as c = 0.95 - 0.0088z [ 39] where z i s as p r e v i o u s l y d e f i n e d . S u b s t i t u t i n g v a l u e s f o r L, y and c as g i v e n i n e q u a t i o n s [ 3 7 ] , [ 3 8 ] , and [39] r e s p e c t i v e l y , i n t o e q u a t i o n [ 3 6 ] , P now becomes t h e l o a d on t h e f e e d r o l l a t any d i s t a n c e z measured F i g u r e 37 D e t e r m i n i n g cane t a p e r as a f u n c t i o n o f t h e p o i n t o f l o a d a p p l i c a t i o n - 84 -r e a r w a r d from th e f r o n t end o f t h e f e e d r o l l . The t o t a l l o a d imposed by twenty canes e v e n l y spaced a t 3 i n c h e s a l o n g t h e 5 f o o t h o r i z o n t a l l e n g t h o f t h e f e e d r o l l i s E v a l u a t i n g e q u a t i o n [40] based on I - 0.0052 i n 2 ° and E = 455,000 l b / i n ( d a t a f o r t h e same cane as d e s c r i b e d i n f i g u r e 3 7 ) , t h e t o t a l h o r i z o n t a l r e a c t i o n f o r c e between one f e e d r o l l and the canes i t compresses was e s t i m a t e d a t 249 l b s . The r e a c t i o n f o r c e v a r i e d from 118 l b s . a t t h e f r o n t o f t h e f e e d r o l l t o 0.3 5 l b s . a t t h e r e a r o f t h e f e e d r o l l . Even though e q u a t i o n [36] u n d e r e s t i m a t e s t h e l o a d f o r l a r g e d e f l e c t i o n s , due t o s i m p l e beam t h e o r y , t h e above c a l c u l a t e d v a l u e f o r t o t a l r e a c t i o n f o r c e can be e x p e c t e d t o be h i g h s i n c e i t was assumed t h a t a l l canes and s h o o t s were o f maximum r i g i d i t y , were s u b j e c t e d t o maximum p o s s i b l e d e f l e c t i o n and were r i g i d l y a t t a c h e d t o t h e s o i l s u r f a c e . A n a l y s i s o f cane p r o p e r t i e s i n d i c a t e d l a r g e v a r i a t i o n s i n s i z e , r i g i d i t y and modes o f v i b r a t i o n o f i n d i v i d u a l c a n e s . I f base m o t i o n i s a p p l i e d t o a f i x e d p o i n t on each cane, r e s u l t a n t d i s p l a c e m e n t s a t e q u a l d i s t a n c e s f r om th e p o i n t o f a p p l i c a t i o n w i l l d i f f e r a c c o r d i n g t o t h e p r o p e r t i e s o f t h e i n d i v i d u a l canes. S i n c e maximum a c c e l e r a t i o n d e v e l o p e d a t any p o i n t i n a cane depends upon b o t h f r e q u e n c y and d i s p l a c e m e n t , th e i n e r t i a l f o r c e d e v e l o p e d i n t h e f r u i t w i l l depend upon cane p r o p e r t i e s . I n e r t i a l f o r c e must, however, be c o n t r o l l e d w i t h i n t h e l i m i t s s e t by e q u a t i o n [ 6 ] . T h i s can be a c c o m p l i s h e d o n l y by a p p l y i n g b o t h known d i s p l a c e m e n t and known f r e q u e n c y t o a l l f r u i t b e a r i n g — ,57,60 t o t a l [ 4 0 ] z = 0 , 3 , — T o o l f o r S e l e c t i v e H a r v e s t i n g - 85 -p o r t i o n s o f t h e p l a n t , i n d i c a t i n g t h a t base m o t i o n s h o u l d be a p p l i e d t o a l l the p l a n t . One method o f o b t a i n i n g t h i s d e s i r e d r e s u l t i s by a p p l y i n g t h e base m o t i o n t o t h e f e e d r o l l s ( f i g u r e 38). A l l f r u i t b e a r i n g p o r t i o n s w i l l t h e n be s u b j e c t e d t o the same maximum d i s p l a c e m e n t a t the same f r e q u e n c y as t h e r o l l s pass t h e p l a n t s . Both i n e r t i a s h a k e r s and f i x e d d i s p l a c e m e n t s h a k e r s a r e commonly used f o r base m o t i o n a p p l i c a t i o n i n t r e e f r u i t h a r v e s t -i n g . S i n c e the d i s p l a c e m e n t produced by an i n e r t i a s h a k e r i s a f u n c t i o n o f the r e s i s t i n g l o a d , the maximum a c c e l e r a t i o n produced by an i n e r t i a s h a k e r depends upon p h y s i c a l p r o p e r t i e s o f t h e p l a n t . A f i x e d d i s p l a c e m e n t s h a k e r appears t o be p r e f e r a b l e f o r s e l e c t i v e h a r v e s t i n g o f r a s p b e r r i e s s i n c e i t w i l l produce c o n s t a n t maximum base m o t i o n d i s p l a c e m e n t , i n d e p e n d e n t o f t h e p l a n t c h a r a c t e r i s t i c s . Both t h e f r u i t r e t e n t i o n f o r c e and the F/W r a t i o , f o r f r u i t o f s i m i l a r q u a l i t y , d e c r e a s e d u r i n g t h e h a r v e s t season as i s shown by e q u a t i o n s [23] and [ 2 4 ] , The f o r c e r e q u i r e d f o r f r u i t r e m o v a l t h e r e f o r e depends upon the s p e c i f i c d a t e o f h a r v e s t , i n d i c a t i n g t h a t t h e a p p l i e d base m o t i o n must be a d j u s t e d t o s u i t t h e t i m e o f h a r v e s t . The e x p e c t e d v a r i a t i o n o f f r u i t r e t e n t i o n f o r c e and F/W r a t i o i s summarized i n T a b l e X V I I . TABLE X V I I MEANS AND STANDARD DEVIATIONS OF FRUIT RETENTION FORCE AND F/W RATIO BASED ON DATA COLLECTED IN 1968 F i r s t Day o f F i f t e e n t h Day o f H a r v e s t Season H a r v e s t Season F r u i t R e t e n t i o n F o r c e (gm) 291 - 102 162 - 142 F/W R a t i o 96 - 45 46 - 4 3 - 86 -Po(t) F i g u r e 38 Base m o t i o n a p p l i e d t o t h e f e e d r o l l s S i x t y e i g h t p e r c e n t o f t h e measures d e f i n i n g a normal d i s t r i b u t i o n f a l l w i t h i n t h e range o f t h e mean - one s t a n d a r d d e v i a t i o n , w h i l e 95 p e r c e n t f a l l w i t h i n t h e range o f t h e mean - two s t a n d a r d d e v i a t i o n s . Hence, 84 p e r c e n t o f t h e measures have v a l u e s l e s s t h a n t h e sum o f t h e mean p l u s one s t a n d a r d d e v i a t i o n , and 97.5 p e r c e n t have v a l u e s l e s s t h a n t h e mean p l u s two s t a n d a r d d e v i a t i o n s . The e s t i m a t e d r e q u i r e d base m o t i o n a c c e l e r a t i o n s f o r 50, 84 and 97.5 p e r c e n t f r u i t r e m o v a l , based on the F/W d i s t r i b u t i o n s and e q u a t i o n [ 8 ] , a r e g i v e n i n T a b l e X V I I I . The n e c e s s a r y a c c e l e r a t i o n s f o r o t h e r l e v e l s o f f r u i t r e m o v a l may be e s t i m a t e d by a p p l y i n g e q u a t i o n [ 8 ] t o t h e c o r r e s -p o n d i n g v a l u e s o f F/W t a k e n from t h e c u m u l a t i v e d i s t r i b u t i o n c u r v e s i n f i g u r e 19. TABLE X V I I I CALCULATED BASE MOTION ACCELERATION FOR SEVERAL LEVELS OF FRUIT REMOVAL EFFICIENCY F r u i t Removal F i r s t \"Day o f H a r v e s t F i f t e e n t h Day o f H a r v e s t R e q u i r e d Base R e q u i r e d Base L v c m u v a i Upper L i m i t M o t i o n A c c e l - Upper L i m i t M o t i o n A c c e l -<.percent; Q f p / w e r a t i o n o f F/W e r a t i o n ( f t / s e c 2 ) ( f t / s e c 2 ) 50 84 97.5 96 141 186 3090 4540 5980 46 89 132 1480 2860 4250 The c o l l e c t e d d a t a on f r u i t stem s t r e n g t h a r e not d i r e c t l y a p p l i c a b l e t o d e s i g n o f the p i c k i n g t o o l s i n c e t h e l o a d i n g used i n d e t e r m i n a t i o n o f stem s t r e n g t h i s n o t n e c e s s a r i l y t h e same as a c t u a l stem l o a d i n g d u r i n g m e c h a n i c a l h a r v e s t i n g . F i g u r e 22 shows t h e c u m u l a t i v e d i s t r i b u t i o n o f minimum stem s t r e n g t h ( ot = o°) and hence does n o t g i v e a r e l i a b l e e s t i m a t e o f F^ i n e q u a t i o n [ 6 ] , The t r i a l s on hand p i c k i n g by d i r e c t t e n s i l e f o r c e i n d i c a t e d t h a t i f a l l t h e mature f r u i t i s removed, 30 p e r -c e n t o f t h e f r u i t may have stem damage. I t i s t h e r e f o r e a p p a r e n t t h a t t o p r e v e n t stem damage, f r u i t r e m o v a l e f f i c i e n c y f o r one pass o f t h e h a r v e s t e r must be l e s s t h a n 70 p e r c e n t . O v e r a l l f r u i t r e m o v a l e f f i c i e n c y , c o n s i d e r i n g t h e whole s e a s o n , may be g r e a t e r but o n l y w i t h a d e c r e a s e i n o v e r a l l q u a l i t y o f t h e h a r v e s t e d f r u i t . S i n c e f r u i t r e t e n t i o n f o r c e d e c r e a s e s w i t h f r u i t m a t u r i t y , t h e f r u i t r e m a i n i n g a f t e r one pass o f t h e h a r v e s t e r may be p i c k e d a t a l a t e r d a t e but t h e q u a l i t y o f the r e s u l t i n g f r u i t w i l l be r e d u c e d . S i n c e c o l o r i n d e x i s an i n d i c a t o r o f f r u i t q u a l i t y , t h e a c c e l e r a t i o n r e q u i r e d t o remove f r u i t o f r e d u c e d q u a l i t y may be e s t i m a t e d . F o r example, u s i n g - 88 -e q u a t i o n s [ 2 6 ] and [ 2 8 ] w i t h a f r u i t c o l o r i n d e x o f 85, f r u i t r e t e n t i o n f o r c e i s e s t i m a t e d as 164 grams on the f i r s t day o f h a r v e s t and 110 grams on t h e l a s t day o f h a r v e s t . S i m i l a r l y , u s i n g e q u a t i o n s [27] and [29] w i t h a c o l o r i n d e x o f 85, F/W i s e s t i m a t e d as 67 on t h e f i r s t day o f h a r v e s t and 38 on t h e l a s t day o f h a r v e s t . C o r r e s p o n d i n g r e q u i r e d a c c e l e r a t i o n s f o r f r u i t 2 remo v a l a r e o n l y 2160 and 1220 f t / s e c , r e s p e c t i v e l y . A s i m p l e d e v i c e f o r a p p l y i n g f i x e d d i s p l a c e m e n t base mo t i o n t o t h e f e e d r o l l s i s a s l i d e r c r a n k mechanism. The maxi-mum a c c e l e r a t i o n d e v e l o p e d by a s l i d e r c r a n k mechanism i s ,£L,V = ( A ) H ) 2 r c (1 - k) [ 4 1 ] max D s where k = c r a n k l e n g t h / c o n n e c t i n g r o d l e n g t h r = c r a n k l e n g t h s = a n g u l a r v e l o c i t y o f c r a n k The n e c e s s a r y a m p l i t u d e and f r e q u e n c y f o r f r u i t r e m o v a l may be de t e r m i n e d by c o m b i n i n g e q u a t i o n s [ 8 ] and [ 4 1 ] . F i g u r e 39 shows t h e maximum a c c e l e r a t i o n d e v e l o p e d by a s l i d e r c r a n k mechanism, w i t h a c o n n e c t i n g r o d l e n g t h o f one f o o t , f o r s e v e r a l f i x e d a m p l i t u d e s and a range o f f r e q u e n c i e s . F/W has a l s o been p l o t t e d on t h e o r d i n a t e by r e l a t i n g maximum a c c e l e r a t i o n and F/W t h r o u g h e q u a t i o n [ 8 ] , T h i s f i g u r e may be used f o r d e t e r m i n i n g t h e base m o t i o n c h a r a c t e r i s t i c s which w i l l d e v e l o p t h e r e q u i r e d a c c e l e r a -t i o n s l i s t e d i n T a b l e X V I I I . T o o l f o r F r u i t C o l l e c t i o n and Conveying From t h e r e s u l t s o f drop t e s t s d e t e r m i n i n g t h e b r u i s i n g c h a r a c t e r i s t i c s o f r a s p b e r r y f r u i t , i t was found t h a t i f t h e f r e e f a l l d i s t a n c e o f t h e f r u i t i s g r e a t e r t h a n 4.5 cm, t h e impact Frequency (cycles per minute) F i g u r e 39 Maximum a c c e l e r a t i o n d e v e l o p e d by a s l i d e r c r a n k mechanism, w i t h one f o o t c o n n e c t i n g r o d l e n g t h , f o r s e v e r a l a m p l i t u d e s and a range o f f r e q u e n c i e s . The c o r r e s p o n d i n g upper l i m i t o f F/W r a t i o f o r f r u i t r e m o v a l i s a l s o p l o t t e d on t h e o r d i n a t e - 90 -v e l o c i t y must be l i m i t e d t o l e s s t h a n 94 cm/sec (187 f t / m i n ) . S i n c e base motion i s a p p l i e d t o f e e d r o l l s , t h e c o l l e c t i o n t o o l may be no h i g h e r t h a n t h e f e e d r o l l s i f i t i s t o i n t e r c e p t a l l t h e h a r v e s t e d f r u i t . A l t h o u g h most f r u i t removal s h o u l d o c c u r i n t h e r e g i o n o f maximum a c c e l e r a t i o n d i r e c t l y above t h e f e e d r o l l s , i t i s a p p a r e n t t h a t f r u i t w i t h low r e t e n t i o n f o r c e may be removed w h i l e t h e f e e d r o l l s a r e s t i l l a t a c o n s i d e r a b l e d i s t a n c e . A c u s h i o n i n g system, t o l i m i t t h e impact v e l o c i t y o f f r u i t s t r i k i n g t h e c o l l e c t i o n t o o l , t h e r e f o r e appears t o be mandatory. S u b s t i t u t i n g t h e v a l u e s f o r t e r m i n a l v e l o c i t y and a l l o w a b l e impact v e l o c i t y i n t o e q u a t i o n [ 1 7 ] , t h e n e c e s s a r y upward a i r v e l o c i t y s u p p l i e d by a c u s h i o n i n g a i r s t r e a m i s (3960 - 187) * 3800 f t / m i n . Minimum a c c e p t a b l e conveyor s i z e may be e s t i m a t e d from T a b l e s I I I and IV. I f s o r t i n g o r c l e a n i n g s h o u l d t a k e p l a c e on a c o n v e y o r , t h e maximum a l l o w a b l e c o n c e n t r a t i o n o f f r u i t i s a s i n g l e l a y e r o r l e s s . A h a r v e s t i n g r a t e o f 35 l b / m i n ( T a b l e IV) r e p r e s e n t s 7 5 i n d i v i d u a l f r u i t p e r second based on an i n d i v i d u a l f r u i t w e i g h t 3.52 gm. Conveyor d i s c h a r g e v e l o c i t y must be no g r e a t e r t h a n 94 cm/sec t o p r e v e n t b r u i s i n g o f f r u i t e n t e r i n g t h e s t o r a g e t o o l . Assuming a c o n v e y o r v e l o c i t y o f 94 cm/sec and a mean f r u i t d i a m e t e r o f 2.0 cm ( T a b l e I I I ) , a c o n v e y o r o f two cm w i d t h w i l l d e l i v e r 47 i n d i v i d u a l f r u i t p e r second. T h e r e f o r e , t o d e l i v e r a s i n g l e l a y e r o f f r u i t , t h e co n v e y o r w i d t h must be a t l e a s t f o u r cm. S i n c e the d a t a i n T a b l e IV a r e based on a f o r w a r d speed o f one m i l e / h o u r , c o n v e y o r w i d t h f o r h i g h e r speeds o f t r a v e l must be i n c r e a s e d a c c o r d i n g l y . - 91 -T o o l f o r F r u i t S t o r a g e The p e r m i s s i b l e d e p t h o f r a s p b e r r i e s i n a c o n t a i n e r may be e s t i m a t e d by a p p l y i n g e q u a t i o n [ 1 8 ] , n o t i n g t h a t from t h e f o r c e -d e f o r m a t i o n d a t a , K has a v a l u e o f 20Y. The mean and s t a n d a r d d e v i a t i o n o f t a n g e n t modulus from T a b l e V I I I a r e 1.32 and 0.54 r e s p e c t i v e l y . S i n c e s o f t f r u i t may be on t h e bottom l a y e r i n a c o n t a i n e r , a good e s t i m a t e o f r f o r d e t e r m i n i n g the a l l o w a b l e c o m p r e s s i v e l o a d on t h e bottom f r u i t l a y e r i s (1.32 - 0.54) = 0.78 S i n c e b r u i s i n g o f one d r u p e l e t ( T a b l e V) r e p r e s e n t s a b r u i s e depth o f a p p r o x i m a t e l y 1 mm, an o v e r a l l d e f o r m a t i o n o f 1 mm on the l o w e r l a y e r o f f r u i t i n a c o n t a i n e r w i l l n o t r e s u l t i n b r u i s i n g as t h i s r e p r e s e n t s t o t a l d e f o r m a t i o n t h r o u g h o u t the d i a m e t e r o f t h e f r u i t . On t h i s b a s i s , t h e a l l o w a b l e c o m p r e s s i v e l o a d on a s i n g l e f r u i t i s (1) (20) (0.78) = 15.6 gm U s i n g a mean f r u i t w e i g h t o f 3.52 gm and n e g l e c t i n g b r i d g i n g o r i n t e r a c t i o n between i n d i v i d u a l f r u i t , t h i s r e p r e s e n t s 4 l a y e r s o f f r u i t i n t h e c o n t a i n e r . S i n c e average f r u i t d i a m e t e r i s 2 cm, c o n t a i n e r f i l l i n g d e p th must not exceed 8 cm. The n e c e s s a r y s t o r a g e t o o l c a p a c i t y may be e s t i m a t e d from T a b l e IV. A h a r v e s t i n g r a t e o f 35 l b / m i n r e p r e s e n t s 4500 i n d i v i d u a l f r u i t p e r mi n u t e . Based on a mean f r u i t d i a m e t e r o f 2cm and a f i l l i n g d e p th o f 4 l a y e r s o f f r u i t , a c o n t a i n e r w i t h 2 2 s u r f a c e a r e a o f 4500 cm (700 i n ) w i l l be f i l l e d e v e r y m i n u t e . T h i s e s t i m a t e i s based on a f r u i t r e moval e f f i c i e n c y o f 100 p e r -c e n t f o r a f o r w a r d speed o f 1 m i l e p e r hour a t t h e peak o f the - 92 -h a r v e s t season. The e f f e c t o f i n - t r a n s i t v i b r a t i o n s on r a s p b e r r y f r u i t s t o r e d i n c o n t a i n e r s was not e v a l u a t e d . O ' B r i e n e_t a l (26 ,27 ) , i n s t u d i e s on t r a n s p o r t damage t o c l i n g peaches and tomatoes, found t h a t l i m i t i n g v e r t i c a l a c c e l e r a t i o n s t o l e s s t h a n 0.2g red u c e d t r a n s p o r t damage t o a c c e p t a b l e l e v e l s . As s o i l s u r f a c e c o n d i t i o n s i n r a s p b e r r y f i e l d s a r e v e r y u n i f o r m and h a r v e s t e r d e s i g n speed i s one m i l e / h o u r , e x p e c t e d v e r t i c a l a c c e l e r a t i o n s a r e l e s s t h a n 0.2g. The o n l y p r o b a b l e i n - t r a n s i t v i b r a t i o n damage i s i n t r a n s p o r t o f f r u i t from the f i e l d t o t h e p r o c e s s i n g p l a n t . DESIGN AND FABRICATION OF TOOLS I n t r o d u c t o r y Remarks T h i s c h a p t e r summarizes t h e d e s i g n and f a b r i c a t i o n o f the t o o l s s e l e c t e d t o mechanize the p r o c e s s . T o o l d e s i g n was based on t h e s p e c i f i c a t i o n s g i v e n i n t h e p r e v i o u s c h a p t e r w h i l e t h e m a t e r i a l s and methods used were t h o s e w h i c h would a l l o w f a b r i c a -t i o n i n a s m a l l machine shop. No at t e m p t was made t o c r e a t e optimum t o o l d e s i g n s . The purpose o f p r o t o t y p e t o o l s was t o t e s t t h e b a s i c d e s i g n p r i n c i p l e s and t o check t h e v a l i d i t y o f the assu m p t i o n s made d u r i n g the t o o l a n a l y s e s . T o o l f o r F e e d i n g and Cane O r i e n t a t i o n The s e l e c t e d f e e d r o l l i n c l i n a t i o n was 45° w h i l e the s e l e c t e d l e n g t h was 6 f e e t . The f r o n t end o f t h e f e e d r o l l s was d e s i g n e d t o o p e r a t e 1 f o o t above t h e s o i l s u r f a c e . A l t h o u g h f i g u r e 11 i n d i c a t e s t h a t the v e r t i c a l f r u i t d i s t r i b u t i o n b e g i n s a t 0.5 f e e t above t h e s o i l s u r f a c e , t h e l o w e r p o r t i o n o f t h e d i s t r i b u t i o n i s caused by canes w h i c h have grown o u t w a r d , away from t h e c e n t e r o f t h e row. G a t h e r i n g and c o m p r e s s i n g t h e s e canes between the f e e d r o l l s w i l l e f f e c t i v e l y r a i s e t h e l o w e r end o f v e r t i c a l f r u i t d i s t r i b u t i o n c u r v e s above t h e one f o o t l e v e l . Each f e e d r o l l was f a b r i c a t e d by w e l d i n g f o u r , 1/8 i n c h x 2 i n c h x 72 i n c h l o n g , c o l d r o l l e d s t e e l f l a t s i n t h e c o n f i g u r a -t i o n shown i n f i g u r e 40. One i n c h d i a m e t e r , c o l d r o l l e d s t e e l s t u b s h a f t s were i n s e r t e d i n t o each end o f the f a b r i c a t e d s e c t i o n and welded i n p l a c e . The o u t e r s u r f a c e s o f each f e e d r o l l were c o v e r e d w i t h o n e - h a l f i n c h foam r u b b e r a t t a c h e d w i t h c o n t a c t cement. The t o t a l w e i g h t o f each f e e d r o l l was a p p r o x i m a t e l y - 9 3 -F i g u r e 41 Feed r o l l mounting and d r i v e t r a i n - 95 -25 pounds. . The f e e d r o l l s were each a t t a c h e d t o upper and l o w e r sway-b a r s ( f i g u r e 41) by means o f s e l f - a l i g n i n g b a l l b e a r i n g s i n f l a n g e c a r t r i d g e s . The r a d i a l l o a d r a t i n g o f t h e s e l e c t e d b e a r i n g s was 1680 l b a t 100 rpm. T h i s c o r r e s p o n d s t o t h e i n e r t i a l l o a d i n g d e v e l o p e d i n t h e b e a r i n g s f o r a maximum base 2 mot i o n a c c e l e r a t i o n a t 4300 f t / s e c . The f e e d r o l l s were t i m e d 90° o u t o f phase and d r i v e n t h r o u g h a r o l l e r - c h a i n - a n d - g e a r d r i v e t r a i n ( f i g u r e 41) f o r c i n g them t o r o t a t e i n o p p o s i t e d i r e c t i o n s . F r o n t and r e a r f e e d r o l l c l e a r a n c e c o u l d be a d j u s t e d i n d e p e n d e n t l y by r o t a t i o n o f t h e swaybars about t h e i r upper p i v o t p o i n t s . T o o l f o r S e l e c t i v e H a r v e s t i n g O s c i l l a t o r y m o t i o n was a p p l i e d t o the f e e d r o l l s w i t h f o u r s y n c h r o n i z e d c r a n k and c o n n e c t i n g r o d mechanisms, one a t each end o f each f e e d r o l l ( f i g u r e 4 2 ) . The c o n n e c t i n g r o d s , w h i c h had a l e n g t h o f 1 f o o t between p i v o t p o i n t s were f a b r i c a t e d by a t t a c h -i n g s e l f - a l i g n i n g , d o u b l e row, b a l l b e a r i n g , r o d ends t o each end o f 8 i n c h l e n g t h s o f o n e - i n c h s t e e l p i p e . The s e l e c t e d r o d ends had a r a d i a l l o a d l i m i t o f 7090 l b . The c o n n e c t i n g r o d s were a t t a c h e d t o t h e f e e d r o l l swaybars 1 f o o t below t h e i r upper p i v o t p o i n t s . The c r a n k end o f each c o n n e c t i n g r o d was a t t a c h e d t o a s t e e l d i s k c e n t e r e d on a s h a f t ( f i g u r e 4 3 ) . Tapped h o l e s spaced a t 0.25, 0.50, 0.75, 1.00 and 1.25 i n c h e s from t h e c e n t e r o f r o t a t i o n o f t h e d i s k were used f o r a t t a c h i n g t h e c o n n e c t i n g r o d s . T h i s c r e a t e d a p o s s i b l e range o f s t r o k e s from 0.5 t o 2.5 i n c h e s i n 0.5 i n c h i n c r e m e n t s . A l t h o u g h t h i s base m o t i o n d e v i a t e s - 96 -F i g u r e 43 Method o f v a r y i n g t h e base motion a m p l i t u d e s l i g h t l y from s l i d e r c r a n k m o t i o n , t h e d e v i a t i o n f o r t h e range o f s t r o k e s used i s i n s i g n i f i c a n t and t h e c u r v e s p r e s e n t e d i n f i g u r e 39 a r e a p p l i c a b l e . The f o u r c r a n k s were d r i v e n and s y n c h r o n i z e d by means o f a r o l l e r - c h a i n d r i v e t r a i n ( f i g u r e 4 4 ) . The c r a n k s were t i m e d so t h a t t h e l a t e r a l o s c i l l a t i o n o f b o t h f e e d r o l l s was i n phase. F r u i t C o l l e c t i o n , C o nveying and S t o r a g e The p r i m a r y purpose o f the p r o t o t y p e h a r v e s t e r was t o t e s t t h e t o o l s f o r f e e d i n g , cane o r i e n t a t i o n and s e l e c t i v e h a r v e s t i n g . No a ttempt was made t o d e s i g n c o l l e c t i o n , c o n v e y i n g and s t o r a g e t o o l s based on t h e i r p r o posed m a t h e m a t i c a l models. F a b r i c a t i o n o f t h e s e t o o l s may be l o g i c a l l y u n d e r t a k e n a f t e r t e s t i n g and e v a l u a t i o n o f t h e f e e d i n g and s e l e c t i v e h a r v e s t i n g t o o l s . T h i s F i g u r e 44 D r i v e t r a i n f o r a p p l y i n g the base m o t i o n - 98 -a v o i d s unnecessary c o s t i n the i n i t i a l d e s i g n s t a g e s and s i m p l i -f i e s t e s t i n g o f i n d i v i d u a l t o o l s by e l i m i n a t i n g p o s s i b l e i n t e r -a c t i o n . A s i m p l e c o l l e c t i o n and c o n v e y i n g d e v i c e ( f i g u r e 45) c o n s i s t i n g o f n y l o n s c r e e n s , p a s s i n g from the f e e d r o l l sway-ba r s t o the machine frame, was used as a t o o l f o r c o l l e c t i o n and c o n v e y i n g d u r i n g e v a l u a t i o n o f the f e e d i n g and s e l e c t i v e h a r v e s t i n g t o o l s . F r u i t which was i n t e r c e p t e d by the o s c i l l a t i n g s c r e e n s was conveyed t o s t a t i o n a r y s t o r a g e c o n t a i n e r s p l a c e d a t the f r o n t end o f the s c r e e n s . F i g u r e 45 N y l o n s c r e e n s used as temporary c o l l e c t i o n and c o n v e y i n g t o o l s d u r i n g t e s t i n g o f t h e t o o l s f o r f e e d i n g and s e l e c t i v e h a r v e s t i n g . SYNTHESIS AND CONSTRUCTION OF THE MACHINE Purpose o f the P r o t o t y p e Machine As was p r e v i o u s l y s t a t e d , o n l y t h e f e e d i n g , cane o r i e n t a -t i o n and s e l e c t i v e h a r v e s t i n g t o o l s were d e s i g n e d and f a b r i c a t e d on t h e b a s i s o f t h e proposed m a t h e m a t i c a l models. The purpose o f t h e p r o t o t y p e h a r v e s t i n g machine was t o e v a l u a t e the p e r f o r m -ance o f t h e s e t o o l s . T h e c o m p l e t e d machine c o n s i s t e d o f a frame t o s u i t a b l y p o s i t i o n t h e t o o l s i n r e l a t i o n t o t h e p l a n t s , p o w e r i n g systems f o r b o t h f o r w a r d movement and base m o t i o n a p p l i c a t i o n , c o n t r o l systems t o p e r m i t a d j u s t m e n t o f t h e d e s i g n p a r a m e t e r s , d r i v e t r a i n s and s u p p o r t i v e members. Temporary c o l l e c t i o n , c o n v e y i n g and s t o r a g e t o o l s , as p r e v i o u s l y d e s c r i b e d , were a l s o i n c o r p o r a t e d i n the machine. The machine frame was d e s i g n e d t o accommodate the p r oposed t o o l s f o r f r u i t c o l l e c t i o n , c o n v e y i n g and s t o r a g e . I n c o r p o r a t i o n o f t h e s e t o o l s i n t o t h e machine i s a l o g i c a l f i n a l s t e p a f t e r e v a l u a t i o n o f t h e f e e d i n g and h a r v e s t i n g t o o l s . P owering Systems A h a r v e s t i n g machine may be e i t h e r s e l f - p r o p e l l e d o r t r a i l - t y p e . I n t h e l a t t e r c a s e , power i s s u p p l i e d by a t r a c t o r t o w i n g t h e machine, w h i l e i n t h e f o r m e r c a s e , m o t i v e power i s s u p p l i e d by a power u n i t p l a c e d on the h a r v e s t e r . S i n c e the p r o t o t y p e machine s e r v e d o n l y as a c a r r y i n g frame f o r e v a l u a t i o n o f t h e f e e d i n g and h a r v e s t i n g t o o l s , a t r a i l - t y p e c o n s t r u c t i o n was s e l e c t e d due t o l o w e r c o s t and d e s i g n s i m p l i c i t y . The machine was towed w i t h a Massey Ferguson model 65 t r a c t o r w i t h t h e f e e d r o l l s b e i n g d r i v e n from th e t r a c t o r power t a k e - o f f . - 9 9 -F i g u r e 4 6 P l a n view o f t h e h a r v e s t e r - 101 -F i g u r e 4 8 Rear view o f completed machine - 102 -T h i s t r a c t o r was s e l e c t e d as i t had a power t e k e - o f f d r i v e n from t h e t r a n s m i s s i o n , p e r m i t t i n g a u t o m a t i c s y n c h r o n i z a t i o n o f f e e d r o l l speed w i t h speed o f f o r w a r d t r a v e l . The t r a c t o r power t a k e - o f f c o m p l e t e d one r e v o l u t i o n f o r each 21 i n c h e s o f f o r w a r d t r a v e l , n e c e s s i t a t i n g a d r i v e t r a i n r a t i o o f 2.38/1 t o s a t i s f y e q u a t i o n [ 3 5 ] . A s m a l l power u n i t , mounted on t h e h a r v e s t e r , a c t e d as a p o w e r i n g system f o r t h e base m o t i o n . The r e a s o n f o r u s i n g a s e p a r a t e power u n i t f o r base m o t i o n a p p l i c a t i o n was i n o r d e r t o r e a d i l y o b t a i n a l a r g e range o f f r e q u e n c i e s d u r i n g t e s t r u n s . I f a s u i t a b l e base m o t i o n f r e q u e n c y c o u l d be e s t a b l i s h e d , base m o t i o n c o u l d a l s o be powered by the t r a c t o r . Frame and S u p p o r t i n g Members The machine was s u p p o r t e d on two pneumatic wheels and a p i n n e d c o n n e c t i o n a t the t r a c t o r drawbar. Welded r e c t a n g u l a r h o l l o w s t e e l s e c t i o n s (2 i n c h x 2 i n c h x 3/16 i n c h t h i c k ) were used f o r t h e frame members s u p p o r t i n g t h e t o o l s . No assessment o f t h e s t r u c t u r a l s t r e n g t h o f t h e frame was u n d e r t a k e n . A p l a n v iew o f t h e h a r v e s t e r i s shown i n f i g u r e 46, w h i l e two views o f t h e c o mpleted machine a r e shown i n f i g u r e s 47 and 48. T r e l l i s i n g M o d i f i c a t i o n The t r e l l i s i n g system c u r r e n t l y used was not s u i t a b l e f o r t h e h a r v e s t e r s i n c e the s i z e o f p o s t s used t o s u p p o r t the t r e l l i s w i r e s i s o f t e n more t h a n s i x i n c h e s i n d i a m e t e r . T h i s c o u l d cause p o s s i b l e i n t e r f e r e n c e between the f e e d r o l l s and t h e p o s t s . The t r e l l i s i n g system used i n t h e h a r v e s t i n g t e s t p l o t was m o d i f i e d by u s i n g 2 i n c h x 2 i n c h x 36 i n c h h i g h bean p o l e s i n F i g u r e 4 9 View o f machine e n t e r i n g a row. The m o d i f i e d t r e l l i s i n g system i s shown. MACHINE EVALUATION Scope o f T e s t The complete assessment o f machine performance n e c e s s i t a t e s b o t h f u n c t i o n a l t e s t s and d u r a b i l i t y t e s t s . S i n c e l o a d s imposed on a h a r v e s t i n g machine a r e n e a r l y i m p o s s i b l e t o d u p l i c a t e i n a l a b o r a t o r y , a d u r a b i l i t y t e s t must u s u a l l y be co n d u c t e d by o p e r a t i n g t h e machine f o r a s u i t a b l e p e r i o d o f t i m e i n a c t u a l f i e l d c o n d i t i o n s . S i m i l a r l y , c o mplete f u n c t i o n a l e v a l u a t i o n must be t h e r e s u l t o f many hours o f o p e r a t i o n i n d i v e r s e f i e l d c o n d i t i o n s , i n o r d e r t o a s s e s s performance i n a l a r g e v a r i e t y o f f i e l d and c r o p c o n d i t i o n s . Only one 2 0 0 - f o o t - l o n g row o f r a s p b e r r i e s was a v a i l a b l e f o r f i e l d t r i a l s d u r i n g 1969. No d u r a b i l i t y e v a l u a t i o n c o u l d , t h e r e f o r e , be u n d e r t a k e n and o n l y a c u r s o r y assessment o f f u n c t i o n a l performance c o u l d be c o m p l e t e d . S i m i l a r l y , no assessment o f t h e e f f e c t o f f r u i t v a r i e t y c o u l d be u n d e r t a k e n s i n c e o n l y t h e W i l l a m e t t e v a r i e t y was a v a i l a b l e f o r t e s t p u r p o s e s . The r e s u l t s p r e s e n t e d i n t h e f o l l o w i n g d i s c u s s i o n were o b t a i n e d from s i n g l e r u n s f o r each machine s e t t i n g . S i n c e r e p l i c a t e r u n s a r e u s u a l l y r e q u i r e d f o r r e l i a b l e a ssessment, t h e r e s u l t s must be t r e a t e d a c c o r d i n g l y . E v a l u a t i o n o f t h e F e e d i n g and Cane O r i e n t a t i o n T o o l P o s s i b l e i n t e r a c t i o n between t o o l s was e l i m i n a t e d by not power i n g t h e s e l e c t i v e h a r v e s t i n g t o o l d u r i n g assessment o f t h e f e e d i n g and cane o r i e n t a t i o n t o o l . On t h e b a s i s o f l i m i t e d t e s t s , p erformance o f t h e t o o l f o r f e e d i n g and cane o r i e n t a t i o n was s a t i s f a c t o r y . The f e e d r o l l s e f f e c t i v e l y c o n c e n t r a t e d t h e p l a n t s a t t h e p o i n t o f base m o t i o n a p p l i c a t i o n and h e l d t h e canes i n a - 104 -- 105 -v e r t i c a l p o s i t i o n i n d e p e n d e n t o f t h e speed o f f o r w a r d t r a v e l . S y n c h r o n i z a t i o n o f f e e d r o l l r o t a t i o n w i t h f o r w a r d speed was a c h i e v e d . No v i s i b l e p l a n t damage o c c u r r e d f o r a range o f f o r -ward speeds up t o t h r e e m i l e s p e r hour. A l o w e r s p a c i n g o f e i g h t i n c h e s between e x t e r n a l r o l l s u r f a c e s and an upper s p a c i n g o f f o u r i n c h e s r e s u l t e d i n s u f f i c i e n t c o n t a c t w i t h t h e p l a n t s and a l l o w e d t h e r o l l s t o pass t h e m o d i f i e d t r e l l i s i n g system w i t h no i n t e r f e r e n c e . F i g u r e s 50, 51 and 52 i l l u s t r a t e t he a c t i o n o f t h e f e e d r o l l s d u r i n g o p e r a t i o n . E v a l u a t i o n o f t h e S e l e c t i v e H a r v e s t i n g T o o l The method o f a p p l i c a t i o n o f base m o t i o n was s a t i s f a c t o r y . F r u i t b e a r i n g p o r t i o n s o f t h e canes appeared t o r e c e i v e e q u i v a -l e n t d i s p l a c e m e n t s as t h e h a r v e s t e r p a s s e d down t h e row, i n d i c a t i n g t h a t the maximum a c c e l e r a t i o n produced i n t h e f r u i t i n g zone c o u l d be q u i t e c l o s e l y c o n t r o l l e d . The p r e d i c t i o n o f p o s s i b l e f r u i t stem damage, as i n d i c a t e d by t h e measurements o f p h y s i c a l p r o p e r t i e s , was v e r i f i e d d u r i n g f i e l d t e s t i n g o f the s e l e c t i v e h a r v e s t i n g t o o l . From the m a t h e m a t i c a l model f o r t h i s t o o l ( f i g u r e 39) i t can be seen t h a t v a r i o u s c o m b i n a t i o n s o f s t r o k e and f r e q u e n c y may be used t o produce the same maximum a c c e l e r a t i o n . Wang (37) i n s t u d i e s on m e c h a n i c a l c o f f e e h a r v e s t i n g c o n c l u d e d t h a t c o m b i n a t i o n s o f h i g h f r e q u e n c i e s and low a m p l i t u d e s were p r e f e r a b l e t o low f r e q u e n c i e s and h i g h a m p l i t u d e s s i n c e p l a n t d e f l e c t i o n i s s m a l l e r and s h a k i n g t i m e i s r e d u c e d . Both o f t h e s e f a c t o r s may s i g n i f i c a n t l y i n f l u e n c e p l a n t damage. Due t o the s m a l l p l o t s i z e o n l y l i m i t e d assessment o f t h e above v a r i a b l e s c o u l d be c o m p l e t e d . R e s u l t s - 106 -F i g u r e 52 - 107 -and c o n c l u s i o n s based on l i m i t e d t e s t i n g o f the s e l e c t i v e h a r v e s t i n g t o o l may be summarized as f o l l o w s : ( i ) Only f i f t y p e r c e n t o f t h e mature f r u i t c o u l d be removed w i t h no damage t o t h e f r u i t stems i n t h e e a r l y p a r t o f the h a r v e s t s e a s o n . T h i s was a c c o m p l i s h e d w i t h a maximum base 2 m o t i o n a c c e l e r a t i o n o f 2600 f t / s e c , r e s u l t i n g from a 1 i n c h s t r o k e a t a f r e q u e n c y o f 2700 c y c l e s p e r minute. The r e m a i n i n g mature f r u i t c o u l d be removed on subsequent p a s s e s a t l a t e r d a t e s but o n l y w i t h r e d u c t i o n i n f r u i t q u a l i t y . I n s i m i l a r t r i a l s t o w ard the end o f t h e h a r v e s t s e a s o n , a p p r o x i m a t e l y s i x t y f i v e p e r c e n t o f t h e mature f r u i t c o u l d be removed w i t h no a p p r e c i a b l e f r u i t stem damage. 2 ( i i ) I n c r e a s i n g t h e a c c e l e r a t i o n above 2600 f t / s e c i n t h e e a r l y p a r t o f t h e h a r v e s t season i n c r e a s e d f r u i t r e m o v a l but a l s o i n i t i a t e d f a i l u r e o f t h e f r u i t stems. F or example, a 2 maximum a c c e l e r a t i o n o f 4100 f t / s e c , r e s u l t i n g from a s t r o k e o f two i n c h e s a t a f r e q u e n c y o f 2200 c y c l e s p e r m i n u t e , removed a p p r o x i m a t e l y 8 5 p e r c e n t o f t h e mature f r u i t but the r e s u l t i n g f r u i t sample c o n t a i n e d 10 p e r c e n t f r u i t w i t h stems a t t a c h e d , some l e a v e s and some immature f r u i t . The r e q u i r e d a c c e l e r a t i o n s and r e s u l t i n g f r u i t r e moval agree q u i t e c l o s e l y w i t h t h e p r e d i c t e d v a l u e s p r e s e n t e d i n Ta b l e X V I I I . ( i i i ) The f u l l e x t e n t o f t h e damage caused by a p p l y i n g e x c e s s i v e base m o t i o n a c c e l e r a t i o n i s not i m m e d i a t e l y a p p a r e n t . A l t h o u g h f r u i t w i t h stems a t t a c h e d may be o b s e r v e d i n t h e c o l l e c t e d f r u i t , some o f the f r u i t may s u f f e r stem damage but remain a t t a c h e d t o the canes. T h i s f r u i t s u b s e q u e n t l y d i e s and - 108 -i s not a v a i l a b l e a t l a t e r h a r v e s t d a t e s . F i g u r e 53 i l l u s t r a t e s such damage. ( i v ) High f r e q u e n c i e s and low a m p l i t u d e s appeared t o be p r e f e r a b l e t o low f r e q u e n c i e s and h i g h a m p l i t u d e s when p l a n t damage was c o n s i d e r e d . I t was not p o s s i b l e t o conduct s u f f i c i e n t t e s t s on the a v a i l a b l e p l o t t o determine s u i t a b l e l i m i t s o f f r e q u e n c y and a m p l i t u d e . S i m i l a r l y , r e s u l t s on t h e optimum l e n g t h o f time o f base motion a p p l i c a t i o n were i n c o n -c l u s i v e . S i n c e f o r w a r d speeds d u r i n g t e s t runs were one m i l e p e r hour, the s e l e c t i v e h a r v e s t i n g t o o l can be ex p e c t e d t o meet the n e c e s s a r y c a p a c i t y r e q u i r e m e n t s o f one a c r e p e r hour, as p r e v i o u s l y d e t e r m i n e d . F i g u r e 53 F r u i t stem damage due t o e x c e s s i v e base motion a c c e l e r a t i o n - 109 -(v) A l t h o u g h i t i s p o s s i b l e t o remove a l l t h e mature f r u i t on a p l a n t f o r each pass o f the h a r v e s t e r by a p p l y i n g s u f f i c i e n t base m o t i o n a c c e l e r a t i o n , t h i s i s not f e a s i b l e f o r two r e a s o n s . Hand s o r t i n g o f the f r u i t i s r e q u i r e d b e f o r e the p r o c e s s o r w i l l a c c e p t i t . S e c o n d l y , t h e f r u i t removed d u r i n g s o r t i n g and t h e damaged green f r u i t r e m a i n i n g on the p l a n t s w i l l r e d u ce t h e t o t a l y i e l d f o r t h e season. A more l o g i c a l s o l u t i o n a ppears t o be r e m o v a l o f f rom 50 t o 65 p e r c e n t o f t h e mature f r u i t a t each pass o f t h e h a r v e s t e r , t h e r e m a i n i n g f r u i t b e i n g a l l o w e d t o mature b e f o r e r e m o v a l . T h i s w i l l r e s u l t i n a h i g h o v e r a l l f r u i t removal e f f i c i e n c y f o r t h e whole season but w i t h reduced f r u i t q u a l i t y . E v a l u a t i o n o f Machine C o n s t r u c t i o n The p r i m a r y r e a s o n s f o r u s i n g t r a i l - t y p e c o n s t r u c t i o n f o r t h e h a r v e s t i n g machine were re d u c e d c o s t and d e s i g n s i m p l i c i t y , when compared t o a s e l f - p r o p e l l e d machine. A l t h o u g h t h e purpose o f t h e machine was t o s e r v e as a c a r r i e r frame d u r i n g t o o l e v a l u a t i o n , i t s performance i n d i c a t e d t h a t such a d e s i g n c o u l d p o s s i b l y be used f o r a c o m m e r c i a l r a s p b e r r y h a r v e s t i n g machine. A s e l f - p r o p e l l e d machine has advantages where m a n e u v e r a b i l i t y i s i m p o r t a n t and when t o o l s r e q u i r e a h i g h l e v e l o f s u p e r v i s i o n . S i n c e r a s p b e r r y rows a r e s t r a i g h t , a p u l l - t y p e machine i s s u f f i c i e n t l y m a neuverable, i f h e a d l a n d s a r e o f s u f f i c i e n t w i d t h t o a l l o w u n o b s t r u c t e d t u r n i n g . F u r t h e r m o r e , t h e f e e d i n g and s e l e c t i v e h a r v e s t i n g t o o l s r e q u i r e l i t t l e s u p e r v i s i o n , once t h e y have been a d j u s t e d t o s u i t c r o p c o n d i t i o n s . The f i n a l c h o i c e between a t r a i l - t y p e o r s e l f - p r o p e l l e d machine must be based on t h e l e v e l o f s u p e r v i s i o n r e q u i r e d f o r t h e f r u i t s t o r a g e - 110 -t o o l once i t has been i n c o r p o r a t e d i n t h e machine. I f an o p e r a t o r i s r e q u i r e d t o s u p e r v i s e and c o n t r o l t h e f r u i t s t o r a g e t o o l , a s e l f p r o p e l l e d machine would be a l o g i c a l c h o i c e . C o n c l u d i n g Remarks A l t h o u g h performance o f t h e p r o t o t y p e h a r v e s t e r met d e s i g n e x p e c t a t i o n s and the use o f such a machine i n W i l l a m e t t e r a s p -b e r r i e s would be e c o n o m i c a l l y b e n e f i c i a l , o t h e r r a s p b e r r y v a r i e t i e s may be b e t t e r s u i t e d t o m e c h a n i c a l h a r v e s t i n g . The r e t e n t i o n f o r c e , c o l o r and f i r m n e s s o f mature r a s p b e r r y f r u i t a r e s t r o n g l y dependent upon f r u i t v a r i e t y ( 1 0 ) . V i s u a l o b s e r v a -t i o n o f the f r u i t a t t achment systems o f s e v e r a l d i f f e r e n t r a s p b e r r y v a r i e t i e s i n d i c a t e d t h a t two v a r i e t i e s , C h i e f and Red Radabout, have f r u i t c o r e s which a r e much s h a l l o w e r t h a n the c o r e s i n t h e W i l l a m e t t e v a r i e t y ( f i g u r e 5 4 ) . L i m i t e d c o m p a r i s o n i n d i c a t e d t h a t due t o the c o r e c o n f i g u r a t i o n t h e f r u i t r e t e n t i o n f o r c e , f o r f r u i t o f s i m i l a r c o l o r and f i r m n e s s , was a p p r e c i a b l y l o w e r f o r t h e s e v a r i t i e s t h a n f o r t h e W i l l a m e t t e v a r i e t y . The r e c e n t l y d e v e l o p e d M a t s q u i v a r i e t y i s a l s o r e p o r t e d t o have l o w e r f r u i t r e t e n t i o n f o r c e t h a n the W i l l a m e t t e v a r i e t y ( 7 ) . The n e x t l o g i c a l s t e p i n development o f a r a s p b e r r y h a r v e s t i n g system t h e r e f o r e s h o u l d be i n v e s t i g a t i o n o f p h y s i c a l p r o p e r t i e s o f o t h e r s u i t a b l e v a r i e t i e s o f r a s p b e r r i e s t o f i n d a v a r i e t y w i t h a l o w e r r a t i o o f f r u i t r e t e n t i o n f o r c e t o f r u i t stem s t r e n g t h . A b r e e d i n g program aimed a t d e v e l o p i n g a r a s p b e r r y v a r i e t y more s u i t a b l e f o r m e c h a n i c a l h a r v e s t i n g s h o u l d a l s o be u n d e r t a k e n . F u r t h e r work on t h e use o f growth r e g u l a t o r s w i t h the aim - I l l -o f r e d u c i n g f r u i t r e t e n t i o n f o r c e i s a l s o i n d i c a t e d . I n i t i a l t r i a l s i n d i c a t e d t h a t s u i t a b l e growth r e g u l a t o r t r e a t m e n t s c o u l d s i g n i f i c a n t l y a l t e r f r u i t r e t e n t i o n f o r c e and i t s v a r i a t i o n o v e r t h e h a r v e s t season. A l t h o u g h no machine t r i a l s were co n d u c t e d on t h e p l o t s r e c e i v i n g growth r e g u l a t o r t r e a t m e n t s , measurement o f p h y s i c a l p r o p e r t i e s i n d i c a t e d t h a t growth r e g u l a t o r t r e a t m e n t s c o u l d be b e n e f i c i a l . Treatment 14 ( T a b l e XIV) f o r example, c o u l d p o s s i b l y i n c r e a s e f r u i t r e m o v a l a t t h e b e g i n n i n g o f t h e h a r v e s t s e a s o n , s i n c e i t s i g n i f i c a n t l y r e d u c e d f r u i t r e t e n t i o n f o r c e e a r l y i n t h e h a r v e s t season. Willamette variety Other varieties F i g u r e 54 The i n f l u e n c e o f f r u i t c o r e shape on f r u i t r e t e n t i o n f o r c e OBSERVATIONS AND CONCLUSIONS The f o l l o w i n g i s a summary o f t h e n a t u r e and scope o f t h e c o m pleted s t u d y , t h e r e s u l t s o f t h e e x p e r i m e n t a l i n v e s t i g a t i o n s and t h e subsequent c o n c l u s i o n s . The s t u d y a p p l i e s s p e c i f i c a l l y t o r a s p b e r r y p r o d u c t i o n i n t h e B r i t i s h Columbia l o w e r m a i n l a n d . C o n c l u s i o n s a r e based on r e s u l t s o b t a i n e d from i n v e s t i g a t i o n o f the W i l l a m e t t e v a r i e t y o f r a s p b e r r i e s . Other r a s p b e r r y v a r i e t i e s may be e x p e c t e d t o produce q u i t e d i f f e r e n t r e s u l t s . 1. A s y s t e m a t i c d e s i g n p r o c e d u r e , o r i e n t e d toward d e s i g n and t e s t i n g o f a b i o l o g i c a l - m a c h i n e - s y s t e m was used t o d e v e l o p a m e c h a n i c a l r a s p b e r r y h a r v e s t i n g system. The s e l e c t e d d e s i g n was based on t h e p h y s i c a l and m e c h a n i c a l p r o p e r t i e s o f t h e r a s p b e r r y p l a n t and t h e e x i s t i n g economic c o n d i t i o n s i n t h e r a s p b e r r y i n d u s t r y . 2. An economic s t u d y , comparing p r e s e n t hand h a r v e s t i n g methods i n t h e l o w e r m a i n l a n d t o a t h e o r e t i c a l m e c h a n i c a l h a r v e s t i n g system i n d i c a t e d t h a t : (a) A machine w i t h g r o s s s e a s o n a l f r u i t r e m o v a l e f f i c i e n c y o f 40 t o 60 p e r c e n t w i l l s a t i s f a c t o r i l y compete w i t h t h e p r e s e n t c o s t o f hand h a r v e s t i n g . (b) Machine c a p a c i t y s h o u l d be a t l e a s t one a c r e p e r hour. T h i s r e p r e s e n t s a minimum d e s i g n speed o f one m i l e p e r h our. ( c ) F o r the range o f y i e l d s e x p e c t e d i n t h e l o w e r m a i n l a n d , t h e b r e a k - e v e n p o i n t i s not s t r o n g l y dependent upon machine p u r c h a s e p r i c e , f o r p r i c e s under $11,500, p r o v i d e d t h a t machine c a p a c i t y i s a t l e a s t one a c r e - 112 -p e r hour. (d) A machine which h a r v e s t s f r u i t s u i t a b l e o n l y f o r p r o c e s s i n g w i l l s e r v e o v e r 95 p e r c e n t o f the i n d u s t r y . Measurement o f t h e p h y s i c a l and m e c h a n i c a l p r o p e r t i e s o f the r a s p b e r r y p l a n t and i t s f r u i t was u n d e r t a k e n i n o r d e r t o d e t e r m i n e p e r t i n e n t d e s i g n p a r a m e t e r s . R e s u l t s may be summarized as f o l l o w s : (a) The r e s u l t s o f t h i s i n v e s t i g a t i o n w i l l p r o v i d e u s e f u l i n f o r m a t i o n f o r t h e d e s i g n o f b o t h f i e l d and p r o c e s s -i n g equipment f o r cane f r u i t s . (b) C o r r e l a t i o n s among f r u i t p r o p e r t i e s and t h e f o r c e -d e f o r m a t i o n m o d u l i o b t a i n e d from f l a t p l a t e l o a d i n g o f t h e r a s p b e r r y f r u i t , i n d i c a t e d t h a t t a n g e n t modulus and f r u i t c o l o r a r e d i r e c t i n d i c a t o r s o f f r u i t q u a l i t y . ( c ) S i g n i f i c a n t c o r r e l a t i o n s among f r u i t r e t e n t i o n f o r c e , F/W r a t i o , f r u i t c o l o r and f o r c e - d e f o r m a t i o n m o d u l i showed t h a t b o t h f r u i t r e t e n t i o n f o r c e and F/W r a t i o a r e i n d i r e c t i n d i c a t o r s o f f r u i t q u a l i t y . D e s i g n o f a s e l e c t i v e h a r v e s t i n g t o o l c o u l d be based on e i t h e r o f t h e s e p a r a m e t e r s . (d) S i n c e f r u i t r e t e n t i o n f o r c e and F/W r a t i o were n e g a t i v e l y c o r r e l a t e d w i t h h a r v e s t t i m e , a s e l e c t i v e h a r v e s t i n g d e v i c e e m p l o y i n g e i t h e r o f t h e s e p a r a -meters must be a d j u s t e d t o s u i t the d e s i r e d s e l e c t i o n l e v e l f o r t h e p a r t i c u l a r h a r v e s t day. (e) F r u i t r e t e n t i o n f o r c e and F/W r a t i o appear t o be dependent upon e n v i r o n m e n t a l c o n d i t i o n s and may v a r y - 114 -s i g n i f i c a n t l y from season t o season. ( f ) The W i l l a m e t t e v a r i e t y o f r a s p b e r r i e s was found t o have a h i g h r a t i o o f f r u i t r e t e n t i o n f o r c e t o f r u i t stem s t r e n g t h . On t h e b a s i s o f t h e s e measurements, i t was shown t h a t t h e f r u i t removal e f f i c i e n c y d u r i n g a s i n g l e pass o f a m e c h a n i c a l h a r v e s t e r must be l e s s t h a n 70 p e r c e n t , i f damage t o t h e f r u i t a t t a c h m e n t system i s t o be w i t h i n a c c e p t a b l e l i m i t s . High o v e r a l l e f f i c i e n c y may be o b t a i n e d but o n l y by h a r v e s t i n g f r u i t o f r e d u c e d q u a l i t y . (g) Due t o low f r u i t stem s t r e n g t h and h i g h f r u i t r e t e n t i o n f o r c e , t h e f o r c e a p p l i e d t o t h e f r u i t by a m e c h a n i c a l r a s p b e r r y h a r v e s t i n g system must be c l o s e l y c o n t r o l l e d t o p r e v e n t f r u i t stem damage and t o o b t a i n maximum a l l o w a b l e e f f i c i e n c y o f f r u i t r e m o v a l . T h i s i n d i c a t e s t h a t i f v i b r a t o r y h a r v e s t i n g methods a r e used, base m o t i o n must be a p p l i e d t o t h e complete f r u i t i n g zone o f t h e p l a n t . The wide v a r i a t i o n i n f l e x u r a l s t r e n g t h and s i z e o f t h e r a s p b e r r y canes i n d i c a t e s t h a t a p p l i c a -t i o n o f base m o t i o n t o a f i x e d p o i n t on t h e canes i s not f e a s i b l e . 4. M a t h e m a t i c a l models f o r t h e v a r i o u s t o o l s r e q u i r e d i n a m e c h a n i c a l r a s p b e r r y h a r v e s t i n g system were c o n s t r u c t e d , based on t h e p h y s i o - m e c h a n i c a l p r o p e r t i e s o f t h e p l a n t and i t s f r u i t . The t o o l s c o n s i d e r e d were a t o o l f o r f e e d i n g and cane o r i e n t a t i o n , a t o o l f o r s e l e c t i v e h a r v e s t i n g , a t o o l f o r f r u i t c o l l e c t i o n and c o n v e y i n g and a t o o l f o r - 115 -f r u i t s t o r a g e . 5. F u l l s c a l e models o f t h e f e e d i n g and cane o r i e n t a t i o n t o o l and the s e l e c t i v e h a r v e s t i n g t o o l were f a b r i c a t e d and i n c o r p o r a t e d i n t o a p r o t o t y p e h a r v e s t e r . L i m i t e d f i e l d t e s t i n g i n d i c a t e d t h a t t o o l performance met d e s i g n expec-t a t i o n as p r e d i c t e d by measurement o f p h y s i c a l p r o p e r t i e s o f t h e r a s p b e r r y p l a n t . T e s t r e s u l t s i n d i c a t e d t h e f o l l o w i n g l i m i t a t i o n s on m e c h a n i c a l h a r v e s t i n g o f W i l l a m e t t e r a s p b e r r i e s : (a) Due t o a c o m b i n a t i o n o f h i g h f r u i t r e t e n t i o n f o r c e and low f r u i t stem s t r e n g t h , o n l y 50 p e r c e n t o f the mature f r u i t c o u l d be removed i n one pass o f the h a r v e s t e r a t t h e b e g i n n i n g o f t h e h a r v e s t season w i t h o u t f r u i t stem damage. L a t e i n the h a r v e s t season a p p r o x i m a t e l y 6 5 p e r c e n t o f t h e mature f r u i t c o u l d be removed i n one pass o f t h e h a r v e s t e r w i t h o u t f r u i t stem damage. The f r u i t r e m a i n i n g on t h e p l a n t s a f t e r one pass o f the h a r v e s t e r c o u l d be s a t i s f a c t o r i l y removed on subsequent p a s s e s a t l a t e r d a t e s , a s f r u i t r e t e n t i o n f o r c e d e c r e a s e s w i t h i n c r e a s e d m a t u r i t y . (b) O v e r a l l f r u i t r e m o v a l e f f i c i e n c y may approach 100 p e r -c e n t f o r t h e whole h a r v e s t season even though maximum a l l o w a b l e f r u i t r e m o v a l e f f i c i e n c y i s much l o w e r f o r a s p e c i f i c h a r v e s t d a t e . ( c ) The q u a l i t y o f f r u i t o b t a i n e d by a m e c h a n i c a l h a r v e s t i n g w i l l be l o w e r t h a n the q u a l i t y o b t a i n e d by hand p i c k i n g . T h i s i s due t o t h e f a c t t h a t t h e f r u i t must, on the whole, be more mature f o r removal by m e c h a n i c a l methods. The f r u i t o b t a i n e d by m e c h a n i c a l h a r v e s t i n g w i l l , t h e r e f o r e , be s u i t a b l e o n l y f o r p r o c e s s i n g ; i t w i l l not be s u i t a b l e f o r the f r e s h f r u i t market. (d) I n s p i t e o f low f r u i t r e m o v a l e f f i c i e n c y and reduced f r u i t q u a l i t y , use o f t h i s m e c h a n i c a l h a r v e s t i n g system c o u l d be e c o n o m i c a l l y b e n e f i c i a l when compared w i t h t h e c o s t o f hand h a r v e s t i n g . I n i t i a l t r i a l s on the use o f two c h e m i c a l growth r e g u l a t o r s i n d i c a t e d t h a t growth r e g u l a t o r a p p l i c a t i o n c o u l d s i g n i f i -c a n t l y i n f l u e n c e t h e f r u i t r e t e n t i o n f o r c e and F/W r a t i o . The e f f e c t o f the growth r e g u l a t o r was found t o be dependent upon t h e ty p e o f r e g u l a t o r , i t s d a t e o f a p p l i c a -t i o n and i t s c o n c e n t r a t i o n . The p r o p e r use o f growth r e g u l a t o r s c o u l d p o s s i b l y improve t h e performance o f a m e c h a n i c a l h a r v e s t e r i n W i l l a m e t t e r a s p b e r r i e s . A l t h o u g h m e c h a n i c a l h a r v e s t i n g o f W i l l a m e t t e r a s p b e r r i e s was shown t o be e c o n o m i c a l l y b e n e f i c i a l , and t h e proposed h a r v e s t e r d e s i g n c o u l d be used f o r h a r v e s t m e c h a n i z a t i o n , t h e W i l l a m e t t e v a r i e t y i s n o t e s p e c i a l l y s u i t a b l e f o r m e c h a n i c a l h a r v e s t i n g . C u r s o r y e x a m i n a t i o n o f t h e f r u i t a t t a chment systems o f o t h e r r a s p b e r r y v a r i e t i e s i n d i c a t e d t h a t s e v e r a l v a r i e t i e s may be much more s u i t a b l e f o r m e c h a n i c a l h a r v e s t i n g . SUGGESTIONS FOR FURTHER STUDY A l t h o u g h i t has been shown t h a t m e c h a n i c a l h a r v e s t i n g o f the W i l l a m e t t e v a r i e t y o f r a s p b e r r i e s i s f e a s i b l e , the h i g h r a t i o o f f r u i t r e t e n t i o n f o r c e t o f r u i t stem s t r e n g t h l i m i t s f r u i t r e m o v a l e f f i c i e n c y and r e d u c e s the o v e r a l l q u a l i t y o f machine h a r v e s t e d f r u i t . The f o l l o w i n g i n v e s t i g a t i o n s a r e t h e r e f o r e proposed f o r f u t u r e s t u d y : 1. Measurement o f t h e p h y s i c a l and m e c h a n i c a l p r o p e r t i e s o f o t h e r s u i t a b l e v a r i e t i e s o f r a s p b e r r i e s s h o u l d be under-t a k e n i n an attempt t o f i n d a v a r i e t y h a v i n g a l o w e r r a t i o o f f r u i t r e t e n t i o n f o r c e t o f r u i t stem s t r e n g t h . 2. F u r t h e r i n v e s t i g a t i o n s h o u l d be conducted c o n c e r n i n g the p o s s i b i l i t y o f l o w e r i n g f r u i t r e t e n t i o n f o r c e t h r o u g h t h e use o f growth r e g u l a t o r s . 3. A r a s p b e r r y b r e e d i n g program s h o u l d be i n i t i a t e d w i t h t h e aim o f d e v e l o p i n g a v a r i e t y s u i t a b l e f o r m e c h a n i c a l h a r v e s t i n g . An i d e a l v a r i e t y would have a low r a t i o o f f r u i t r e t e n t i o n f o r c e t o f r u i t stem s t r e n g t h , would have f r u i t t h a t matured u n i f o r m l y and would have s u f f i c i e n t cane s t r e n g t h t o e l i m i n a t e t h e need f o r a t r e l l i s i n g system. - 117 -LITERATURE CITED 1. A d r i a n , P.A., F r i d l e y , R. B. and L o r e n z e n , C. \" F o r c e d V i b r a t i o n o f a Tree Limb.\" T r a n s a c t i o n s o f the ASAE,8:(4), p. 473-475, ( 1 9 6 5 ) . 2. American S o c i e t y o f A g r i c u l t u r a l E n g i n e e r s . A n n o t a t e d B i b l i o g r a p h y o f t h e E n g i n e e r i n g P r o p e r t i e s o f B i o l o g i c a l M a t e r i a l s . S t . J o s e p h , M i c h i g a n : American S o c i e t y o f A g r i c u l t u r a l E n g i n e e r s , S p e c i a l P u b l i c a t i o n SP-03-67, pp. 103, ( 1 9 6 7 ) . 3. American S o c i e t y o f A g r i c u l t u r a l E n g i n e e r s . 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Wang, J.K. \" M e c h a n i c a l C o f f e e H a r v e s t i n g \" , T r a n s a c t i o n s o f the ASAE, 8 : ( 3 ) , p. 400-405, (1965). "@en ; edm:hasType "Thesis/Dissertation"@en ; edm:isShownAt "10.14288/1.0102263"@en ; dcterms:language "eng"@en ; ns0:degreeDiscipline "Mechanical Engineering"@en ; edm:provider "Vancouver : University of British Columbia Library"@en ; dcterms:publisher "University of British Columbia"@en ; dcterms:rights "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en ; ns0:scholarLevel "Graduate"@en ; dcterms:title "Mechanical raspberry harvesting"@en ; dcterms:type "Text"@en ; ns0:identifierURI "http://hdl.handle.net/2429/35054"@en .