UBC Theses and Dissertations
Recursive spline trajectory generation and automated cycle time prediction Zeybek, Atakan
Increasing demand for production speed on 5-axis computerized numerical control (CNC) machining technology has led the research studies to improve the precision and predict the machining cycle time hence the cost of manufacturing from the numerical control (NC) part programs. In this study, a recursive trajectory generation of splined paths is proposed to decrease the feed rate fluctuation. The trajectory points are found by the iterative bisection method to improve the accuracy by reducing the interpolation error. Next, the spline toolpath is interpolated backward from the end of the toolpath to generate the reference trajectory points. A full state feedback controller is introduced to force the tangential velocity to follow the desired motion trajectory and reference tool path points. Commercial CNC systems have hidden trajectory motion profilers that are difficult to model analytically. The thesis presents the identification of finite impulse response (FIR) filter settings of the machines from a standard tool path test conducted on the machine tool. The hidden corner strategy of the machine as a function of tolerance is approximated as an exponential function, and its empirical parameters are also identified from the same tool path test data. The NC part program with linear and circular tool path segments is parsed and the total machining time, i.e. cycle time, is estimated using the identified trajectory profile settings of the machine. The proposed cycle time prediction method is experimentally validated with 95% accuracy.
Item Citations and Data
Attribution-NonCommercial-NoDerivatives 4.0 International