Sliding Mode Control Theory And Its Application In Mobile Manipulators

In recent years, sliding mode control receives wide attention because of its simplicity, quick response, robustness and easy realization. Moreover, the theory research and application reports of sliding mode control appear in the field of state estimation, discrete-time system control, time delay control, robust control for uncertain systems, adaptive control, output feedback control and so on.Due to their large workspace and flexible manipulation, nonholonomic mobile manipulators have an extensive background of applications, and have attracted great attention in the international academic and industrial fields. A mobile manipulator that consists of a mobile platform and a manipulator is a typical nonholonomic dynamic system with high nonlinearity and strong coupling, and therefore, it is very difficult to control. It is also a typical MIMO nonlinear uncertain system with parametric uncertainty in the dynamic model including motor dynamics and disturbances from the external environments or unmodelled dynamics etc. Thus, it has generality and representability to study control problems of nonholonomic mobile manipulators.This thesis proposes several new control system design techniques for tracking control and stabilizing control of typical nonlinear systems. The key components of the control design are the use of sliding mode control, Lyapunov stability theory, backstepping, robust control, and adaptive control etc. The dynamic model of nonholonomic mobile manipulators is directly used in all researches. The main topics are as follows:Firstly, a general design method of dynamical sliding mode control is described and a high order dynamical sliding mode control algorithm is proposed for MIMO nonlinear systems in order to solve the chattering of sliding model control. Comparing with conventional sliding mode control, the proposed method can reduce and even eliminate the chattering in the control input. Moreover, the chattering generated by the switching can also be reduced. So, the dynamic performance of the system can be improved greatly.Secondly, a novel robust adaptive sliding mode control algorithm is proposed for MIMO nonlinear systems with parametric uncertainty, input gain uncertainty and unmatched uncertainty that can not be directly solved by sliding motion. It improves the performance of the system by adding sliding mode control in the last step of the...