Control of Unknown Nonlinear System using Gain-Scheduling Tuning Regulators

This paper considers an extension of the tuning regulator design method of [1]-[3] to include a large class of nonlinear multivariable systems. In particular, it is desired to solve the servomechanism problem for an unknown nonlinear plant, which is assumed to be open loop asymptotically stable, for the class of constant set-points and disturbances. In this case, three classes of nonlinear controllers, which are gain-scheduling controllers, are described: (i) error attenuation, (ii) feedforward and (iii) robust controllers, and sufficient conditions by which the resultant closed loop system gives global asymptotic stability and regulation are obtained. The sufficient conditions obtained simplify to the necessary and sufficient conditions [1] associated with the case when the plant is assumed to be described by a linear time-invariant model.