Variable Structure Control Based on Fuzzy Law for Underactuated Robot Manipulators

This paper presents a stable sliding-mode control method for horizontal underactuated 2-DOF robot manipulators. First we define a two-level sliding surface for the whole system by divide the system into two subsystems. Then we use the Lyapunov feedback law to design a controller for the system with the fuzzy controller automatically tunes the slopes of sliding mode surface on line. The asymptotic stability of the sliding surfaces is established and proved theoretically in Lyapunov sense. Simulation results on the underactuated manipulators show that the whole system can be drive to the desire positions and get better system dynamic performance than the normal sliding mode control