Continuous sliding mode control design for a class of MIMO nonlinear uncertain systems: Theory and experiment

In this paper, a new and systematic approach to design a continuous sliding mode control (CSMC) for tracking control of a class of MIMO nonlinear uncertain systems is presented. The proposed method is designed based on online estimation of the uncertainties instead of using the upper bound of uncertainties which is difficult or impossible to find in many cases. The on-line estimation of the uncertainties is performed using proportional-integral action of sliding function. Therefore, two main drawbacks of conventional SMC, namely: the chattering phenomenon; and the requirement for a priori knowledge of the bounds of the uncertainties are addressed. The simulation and experimental results revealed that the proposed method is robust against unmodelled dynamics, external disturbances, and time-varying parameters and its simplicity makes the approach attractive for real-time applications.