A tracking controller for for a class of smooth nonlinear systems

In this paper, preliminary results on a feedforward tracking controller for smooth nonlinear systems is presented. The system is linearized first around a nominal trajectory, and a feedforward controller is designed for the linearized system. Then the feedforward gains are readjusted to ensure zero steady state error. The new gains are given in the form of a lookup table. For a ramp reference function, the new gains are given as a vector function of the reference input and its derivative, or, equivalently as a function of the reference input and its delayed value. Only ramp reference input is considered in the paper. The extension to higher order reference functions is cumbersome but straightforward