(A) study on adaptive control schemes applicable for robot manipulators

Abstract

In this dissertation, adaptive control methods are studied for the robot manipulator to track nominal trajectory as closely as possible in spite of the highly nonlinear and coupled manipulator dynamics and parameter uncertainties of links and payload. First, a centralized adaptive control scheme is developed based on the Lyapunov direct method and a linearized perturbation equation of the manipulator dynamics around the nominal trajectory and parameters of links and payload. And a condition of asymptotic stability is derived. Then the centralized adaptive control scheme is applied to form a control scheme for the manipulator which consists of two components: a nominal control and a variational control. The nominal control, which drives the manipulator to the neighborhood of the trajectory, is generated from the direct calculation of the manipulator dynamics along the nominal trajectory and parameters of links and payload. The variational control, which regulates the perturbation in the vicinity of the nominal trajectory, is obtained from the developed adaptive control scheme. Next, a decentralized adaptive control scheme is also presented to avoid the defects of the centralized control scheme from the standpoints of production and maintenance. It is based on the Lyapunov direct method and an input-decentralized form of the linearized perturbation equation of the manipulator dynamics, and a condition of asymptotic stability is derived. The decentralized adaptive control scheme is also applied to generate the variational control for the manipulator. Computer simulation studies were conducted to evaluate and compare the performances of the proposed manipulator control schemes with those of the conventional control schemes.