Semiglobal robust decentralized tracking control for a class of uncertain MIMO nonlinear systems

The robust decentralized tracking control problem for a class of uncertain multi-input multi-output (MIMO) nonlinear systems in block-triangular form is investigated in this paper. A control design method combining backstepping technique and signal compensation method is proposed to deal with the nonlinear uncertainties, external disturbances and strongly coupled interconnections in this kind of systems. It is proved that, under this method, the semiglobal robust stability and semiglobal robust practical tracking property of the closed-loop system are guaranteed, with the tracking error restrained as small as desired with expected convergence rate. The robust controller is linear and time-invariant, and the explosion of terms in the backstepping control law is avoided.