TRAJECTORY TRACKING IN NONLINEAR-SYSTEMS VIA NONLINEAR REDUCED-ORDER OBSERVERS

The use of nonlinear control methods in control engineering implies, i n general, the knowledge of the full state vector. In this paper we pr esent a nonlinear observer of reduced order (i.e. the order of the obs erver is less than the order of the nonlinear system observed) for est imating the state variables to be used in a trajectory tracking contro l loop. The nonlinear observer has the following characteristics: (1) the speed of convergence is adjustable; (2) the closed-loop control fo r trajectory tracking, with the observer in the loop, is stable. Appli cations to a robot arm and a neural network are included.