- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- UBC Theses and Dissertations /
- Nanovibration control
Open Collections
UBC Theses and Dissertations
UBC Theses and Dissertations
Nanovibration control Greenall, Russ
Abstract
This thesis explores techniques to actively control the position of large masses such as focusing magnets with precision on the order of 1 nm against vibrations. The technique applied (labeled as an "optical anchor") is to actively "stiffen" the support structure using an optical interference method to measure distance to a remote reference point. The magnet is modeled as a mass on a spring, with a piezo electric actuator. In this model, proportional and differential control applied to the piezo allows the mass to be critically damped and the spring coefficient to be arbitrarily increased. A digital implementation with finite sampling rate has a finite stable region in control parameter space. If there are more mechanical degrees of freedom, the stable region and the quality of control can be greatly reduced. An interferometric instrument design for remote distance measurement is discussed and measurement results reflecting an accuracy of 0.2nm RMS are demonstrated. The instrument requires only two light detectors in a Michelson interferometer configuration. The algorithm design is implemented at a 5KHz sample rate using a circa 2000 DSP processor with 4-byte floating point operations running at a 40 MHz clock rate. Control tests on a one degree-of-freedom experimental platform are performed using proportional and differential control. These tests demonstrate active control which significantly damps fundamental mode excitations but are insufficient to stiffen the system. More sophisticated models and algorithms will be necessary. Nevertheless, some insight is gained into techniques which will allow control on the nanometer scale against "standard" ground vibrations. In particular, a successful implementation of coherent ground disturbance modeling provides a three-fold reduction in RMS vibration of our test system over our simple PID control.
Item Metadata
Title |
Nanovibration control
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
2004
|
Description |
This thesis explores techniques to actively control the position of large masses such as
focusing magnets with precision on the order of 1 nm against vibrations. The technique
applied (labeled as an "optical anchor") is to actively "stiffen" the support structure using an
optical interference method to measure distance to a remote reference point. The magnet is
modeled as a mass on a spring, with a piezo electric actuator. In this model, proportional and
differential control applied to the piezo allows the mass to be critically damped and the spring
coefficient to be arbitrarily increased. A digital implementation with finite sampling rate has
a finite stable region in control parameter space. If there are more mechanical degrees of
freedom, the stable region and the quality of control can be greatly reduced.
An interferometric instrument design for remote distance measurement is discussed and
measurement results reflecting an accuracy of 0.2nm RMS are demonstrated. The instrument
requires only two light detectors in a Michelson interferometer configuration. The algorithm
design is implemented at a 5KHz sample rate using a circa 2000 DSP processor with 4-byte
floating point operations running at a 40 MHz clock rate.
Control tests on a one degree-of-freedom experimental platform are performed using
proportional and differential control. These tests demonstrate active control which
significantly damps fundamental mode excitations but are insufficient to stiffen the system.
More sophisticated models and algorithms will be necessary. Nevertheless, some insight is
gained into techniques which will allow control on the nanometer scale against "standard"
ground vibrations. In particular, a successful implementation of coherent ground disturbance
modeling provides a three-fold reduction in RMS vibration of our test system over our simple
PID control.
|
Extent |
16502151 bytes
|
Genre | |
Type | |
File Format |
application/pdf
|
Language |
eng
|
Date Available |
2009-11-24
|
Provider |
Vancouver : University of British Columbia Library
|
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.
|
DOI |
10.14288/1.0091727
|
URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
|
Graduation Date |
2004-11
|
Campus | |
Scholarly Level |
Graduate
|
Aggregated Source Repository |
DSpace
|
Item Media
Item Citations and Data
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.