主講人：C. Steve Suh, Mechanical Engineering Department, Texas A&M University
主題：Nonlinear Time-Frequency Control Theory with Applications
Nonlinear control is an important subject drawing much attention. When a nonlinear system undergoes route-to-chaos, its response is naturally bounded in the time-domain while in the meantime becoming unstably broadband in the frequency-domain. Control scheme facilitated either in the time- or frequency-domain alone is insufficient for mitigating route-to-chaos, where the corresponding response deteriorates in the time and frequency domains simultaneously. It is necessary to facilitate nonlinear control in both the time and frequency domains without obscuring or misinterpreting the true underlying dynamics. The objective is to formulate a novel nonlinear control theory that addresses the fundamental characteristics inherent of all nonlinear systems undergoing route-to-chaos, one that requires no linearization or closed-form solution so that the genuine inherent features of the system being considered are preserved. The theory being presented is able to identify the dynamic state of the system in real-time and restrain time-varying spectrum from becoming broadband. Not subject to all the mathematical constraint conditions and assumptions upon which common nonlinear control theories are based and derived, the novel theory has its philosophical basis established in the simultaneous time-frequency control, on-line system identification, and feedforward adaptive control. The research is of a broad impact on the control of a wide range of nonlinear and chaotic responses including cutting, micro-machining, communication security, electric machines, and mitigation of friction- induced grazing bifurcation. Applications of the theory are elaborated using several examples including the control of a cubic order, non-autonomous time-delayed oscillator, an multi-DOF micro-milling model, PMSM motors, and a discontinuous vibro-impact system.
C. Steve Suh is a faculty in the J. Mike Walker ’66 Mechanical Engineering Department at Texas A&M University. While being the Director of the Institute for Innovation and Design in Engineering (IIDE), he actively promoted university-industry collaborations on developing innovative engineering solutions and providing enhanced design education to engineering students. A seasoned engineer of years of real-world experience, he has worked with a broad spectrum of companies including Ford Motor, Boeing, Schlumberger, Surgimedics, Shell Global Solutions, and Applied Materials, to name a few, on projects ranging from system integration to manufacturing design to software development. His interests in 1) nonlinear time-frequency control theory, 2) advanced manufacturing, 3) engineering design theory, 4) ultrafast laser dynamics, 5) 3D microelectronic packaging, and 6) complex networks have resulted in exceeding 170 scientific publications, 9 book chapters and book volumes including “Control of Cutting and Machining Instability: Time-Frequency Approach for Precision, Micro and Nano Machining” and “Machine Tool Vibrations and Cutting Dynamics.” As the Director of the Nonlinear Engineering and Control Laboratory, Dr. Suh has delivered more than 3 dozens invited speeches on topics ranging from chaos control to innovative design education to dynamic failure theory. He is currently the Editor-in-Chief of Vibration Testing and System Dynamics, an interdisciplinary journal serving as the forum for promoting dialogues among engineering practitioners and research scholars on the synergy of system dynamics, testing, design, modeling, and education. He is also serving as an Associate Editor for the following 3 internationally renowned archival journals - International Journal of Dynamics and Control, Journal of Applied Nonlinear Dynamics, and Discontinuity, Nonlinearity, and Complexity.