Prof. Shyh-Leh Chen

Professor, National Chung Cheng University, Taiwan


Abstract:  Contouring control is an important motion control task for multi-axis motion systems. It requires that the output position of the system follow a given path in the task space. The contouring control problem can be found widely in the applications of robotics, computer-numerical-controlled (CNC) machine tools, etc. It aims at reducing the contour error, which is defined by the minimum distance between the actual output position of the system and the desired path. Improving the contouring accuracy is an important problem since it directly affects the product quality. One major difficulty in this problem is the representation of the contour error in terms of the measurable axis displacements. In general, such representation requires complicated nonlinear functions and analytical form may not be available. Most approaches adopt linear approximation and hence the performance of the contouring controller may be degraded.

In this talk, the concept of equivalent contour error will be introduced. The equivalent contour error is based on the algebraic equations that describe the desired path. It is equivalent to the actual contour error in the sense that reducing it is equivalent to reducing the actual contour error. Thus, the equivalent contour error can be taken as an alternative control objective. No approximations are needed and excellent contouring performance can be achieved. We have developed the method for systems without constraint, with holonomic or non-holonomic constraints. The method has been successfully applied to a variety of practical systems, including multi-axis machine tools, robot manipulators, Stewart platform, and two-wheeled inverted pendulum system.

Bio: Shyh-Leh Chen received B.S and M.S. degrees from National Tsing-Hua University, Hsin-Chu, Taiwan, in 1987 and 1989, respectively, both in power mechanical engineering. He received a Ph.D. degree in mechanical engineering from Michigan State University, East Lansing, Michigan, USA, in 1996. Since 1996, he has been with National Chung Cheng University, Chiayi, Taiwan, where he is currently a Distinguished Professor in the Department of Mechanical Engineering. His research interests include nonlinear dynamics and control, wavelet analysis, with application to motion control of multi-axis systems, active magnetic bearings, and ship stabilization. 

Prof. Chen has organized and chaired 7 international conferences. He received the Automatic Control Award for Young Scholars and Outstanding Automatic Control Award from Chinese Automatic Control Society in 2003 and 2015, respectively, Outstanding Teaching Award from CCU in 2006, Delta Award from IEEE Tainan section in 2017, and Distinguished Research Award from CCU in 2018. He is a Fellow of Chinese Automatic Control Society. He is an associated editor for Mechatronics (since 2021) and IEEE Transactions on Automation Science and Engineering (since 2022).