Causal nonminimum-phase tracking in nonlinear systems: servo-compensator enforced via sliding mode control

A method of robust causal approximate nonminimum phase output tracking is considered. The problem of approximate tracking is solved for one class of nonlinear MIMO systems with uncertainties and external disturbances. Local asymptotic stability of output tracking-error dynamics are provided for systems with linearized internal dynamics forced by a causal reference output profile and external disturbances defined by a known linear exosystem. The technique described employs some linear algebraic methods and sliding mode control (SMC) approach. The solution is a complete constructive algorithm. The controller joins features of a conventional SMC (insensitivity to matched nonlinearities and disturbances) and a conventional dynamic compensator (servo-compensator, accommodation of unmatched disturbances)