Tracking Control of a Robotic System with Initial Constraint Violation and Actuator Faults

In this paper, we address a tracking problems for robotic systems with actuator faults, deferred and constant output constraints. By using an error-shifting transformation into nonsingular terminal sliding mode control (NTSMC) scheme, an novel tracking control is able to develop robotic systems in the present of uncertain initial tracking condition and finite time convergence rate. When the system output violates the prescribed constraint initially, the proposed way makes the prescribed constraints be satisfied within a finite time. In order to make overall closed-loop system achieve uniformly ultimate bounded, a log-type barrier Lyapunov function has been introduced. Moreover, there is no need for the knowledge of the actuator fault, but the actuator faults are accommodated. At last, the finite time converge rate of robotic systems is regulated by choosing appropriate parameters. The controller of this method is implemented to a two-link rigid robot manipulator and results of simulation show that this method can be implemented.