Professor Dong-Il (Dan) Cho

December 20, 2018

Tuningless, High-Performance Nonlinear Servo Control Including Machine Learning: Theory to Practice


High-performance servo controllers are very important in modern automation and robotic systems. Traditionally, the PI control technique has been used, but it demands much tuning process from experienced engineers and does not perform well in many harsh and varying operating conditions. Over the years, we have developed a robust recursive discrete-time sliding mode control (RDVSC) integrated with a novel decoupled disturbance observer and a novel saturation compensator. It is shown that the desirable properties of invariance, finite convergence, and robustness to external disturbances and parametric uncertainties of the continuous-time sliding mode control is preserved in this approach. This method is further integrated with a novel real-time system identification and vibration suppression method. In more complicated applications where in-line approaches do not sufficiently identify the system, off-line machine learning is also used. This advanced controller architecture has been applied to many advanced automation systems, and provide much enhanced robustness and performance in a tuningless setting in the field.


Dong-Il “Dan” Cho received the B.S.M.E. degree from Carnegie-Mellon University (1980), Pittsburg, PA, and the M.S and Ph.D. degrees from the Massachusetts Institute of Technology, Cambridge (1984 and 1988, respectively). From 1987 to 1993, he was an Assistant Professor in the Department of Mechanical and Aerospace Engineering at Princeton University, Princeton, NJ. Since 1993, he has been a Professor in the Department of Electrical and Computer Engineering at Seoul National University, Seoul, Korea. He is the author/coauthor of more than 130 international journal articles. He is the holder/coholder of more than 30 US patents and 80 Korean patents. He has served on the editorial board of many international journals. Currently, he is Senior Editor for IEEE Journal of MEMS and IFAC Mechatronics. He was the President of ICROS and BOG Member of IEEE CSS, and is currently Vice President of IFAC, Chair of the Technical Board of IFAC, and AdCom Member of IEEE EDS. He is an elected Senior Member of National Academy of Engineering of Korea.