An approximation method for the nonlinear servomechanism problem

An analysis of the nonlinear servomechanism problem by the authors (1992) is shown to lead naturally to a straightforward and practical method for solving the problem in an approximate sense. The results are based on a kth-order approximate solution for the plant zero-error manifold, and corresponding control law constructions are shown to yield kth-order asymptotic tracking and disturbance rejection properties for the closed-loop system. The approach is illustrated by application to the ball and beam system.>