Robust adaptive control for a class of partially known nonlinear systems

Abstract

An adaptive controller is developed that takes advantage of the structure and any known dynamics of the system in order to increase speed of adaptation and relax the conditions required for convergence. The control design method has two stages. First, the known dynamics are separated out and used to perform a global linearization on the nonlinear system. Second, a model-reference adaptive control, based on the Lyapunov stability criterion, is designed for the remaining unknown portion of the plant. This control scheme is shown to relax several assumptions usually made in applying adaptive control to a manipulator system. For instance, it relaxes the common assumption that the time-varying plant is close to the desired model.<>