Unstable, nonminimum phase, nonlinear tracking by trajectory linearization control

Abstract

We present a design of a tracking controller for an unstable, nonminimum phase nonlinear plant using trajectory linearization method. The controller consists of two parts: a dynamic inverse and a tracking error stabilizing control law. The nominal control computed by nonlinear pseudo-inverse using nonlinear coordinate transformation and backstepping stabilization, and trajectory stabilization is achieved using linear time-varying (LTV) PD-eigenstructure assignment. Simulation case studies show that significant improvement in tracking performance, robustness and disturbance rejection over the classical and modern gain scheduled controllers can be achieved using rational combinations of nonlinear and LTV control techniques.