Advanced Sliding Mode Control Theory Study in Nonlinear Systems and Applications to Virtual Reality
|School||South China University of Technology|
|Course||Control Theory and Control Engineering|
|Keywords||Zero dynamics Order Sliding Mode Control Immune sliding mode control MIMO nonlinear systems Dynamic sliding mode control Explicit backstepping Nonholonomic mobile robot Virtual Laboratory|
Since the 1980s, there have been breakthrough achievements in the research of nonlinear system control theory, which greatly promote the applications and developments of many complicated nonlinear control system. However, in many cases of practical application, especially when there exist unknown parameters, uncertain disturbances, model errors and unmatched condition in the system, such nonlinear control cannot necessarily obtain the expected results. This makes the robust control of nonlinear uncertain systems with unmatched condition a hot spot of research in the control community during recent years.Because of its simplicity, fast response and robustness with respect to disturbances, Sliding Mode Control (SMC) is very suitable to solve the robust control of nonlinear uncertain systems. But the chattering problem of SMC method may cause the damage of the system hardware or instability of the system. Therefore, its applications in practical systems are limited by this potential threat in the SMC control. To solve this problem, this thesis proposes Immune Sliding Mode(ISM) and Common High Order Sliding Mode (CHOSM) control and Advanced Dynamical Sliding Mode Control (ADSMC). By contrast to the traditional sliding mode control, the former methods can reduce the chattering of the sliding manifolds, and improve the system dynamics and control performance; the latter can reduce and even eliminate the chattering in the control input, and make the SMC controller be easily realized.Meanwhile, aimed at the decouple of MIMO Nonlinear System which is hard to deal with by the tradition method, this thesis adopts Zero-Dynamic and Re-contracture decouple methods. It design procedure is step-by-step and systematic. Many control strategies based on each of the methods provide a systematic frame for the tracking and regulation of a large class of nonlinear uncertain systems. Re-contracture have showed its great advantages in the design of the robust and adaptive controller, especially when the disturbances or uncertainties do not satisfy the matching conditions.Nonholonomic mobile robot has an extensive background of application and has attracted great attention in the international academic and industrial community. It is a typical nonholonomic mechanical system with high nonlinearity and its control is very difficult. It is also a typical nonlinear uncertain system with both the parametric uncertainty in the dynamic model of the robot including motor dynamics and disturbances from the external environment or unmodeled dynamics. This thesis directly applies most of its research to the dynamic model of the robot, which has the generality and representativity of the research.As a part of the NSFC project "Robust control of noninvolutive system with applications to nonholonomic robot systems", this thesis derives the dynamic model of the robot including motor dynamics and realizes its dynamic feedback linearization and robust linearization while considering uncertainties; then it employs HOSM control and DSMC method to achieve the output tracking of the mobile robot; and finally, aimed at the parametric and unmatched uncertainty, it combines the SMC method, backstepping approach and Lyapunov stability theory to realize the robust adaptive output tracking of the robot.The main body of this thesis is composed of the following three parts: the first is the Immune Sliding Mode Control, Common Higher Order Sliding Mode Control and Advance Dynamic Sliding Mode Control with applications to output tracking control of the mobile robot; the second is the Re-Contracture Decouple and Zero Dynamic Decouple method; the last part is the VR lab for Sliding Mode Control theory.