ROBUST CONTROL BY SLIDING MODE FOR A CLASS OF UNCERTAIN UNDERACTUATED SYSTEMS WITH SATURATION

D.W. Qian, J.Q. Yi, X.J. Liu, G.T. Yang, and M.X. Wang

Keywords

Robust control, sliding mode, under-actuated systems, saturation, uncertainty

Abstract

This paper addresses a robust control scheme by hierarchical sliding mode for a class of uncertain under-actuated systems with satura- tion. Such an uncertain system consists of a nominal system and uncertainties. For the nominal system, the hierarchical structure of the sliding surfaces is proposed by capturing its physical structure and its controller is designed by Lyapunov theory. For the uncertainties, its lumped compensator is designed at the last-layer sliding surface. The controller and the compensator work together as the single control input, the saturation constraint of which is considered for engineering applications. Asymptotic stability of the control system with saturation is proven. Parameter ranges of the subsystem sliding surfaces of the nominal system are deduced. Simulation results show the validity of the approach.

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