A VSS CONTROL METHOD FOR A MANIPULATOR DRIVEN BY AN ARTIFICIAL MUSCLEACTUATOR

Compared with the motor actuators and air or oil cylinder actuators, t he artificial muscle actuator has some good characteristics, including lighter weight, larger torque output, and greater safety in places wi th fire hazard, so that the artificial muscle actuator is expected; to expand its application in many areas such as industry and medical ser vice. The actuator has a strong compression effect and hysteresis, and the dynamics of the actuator must be considered in order to achieve s table trajectory tracking control. In the paper, a new VSS controller for the manipulator, which guarantees asymptotic tracking of a desired trajectory, is presented. Based on the nonlinear characteristics of a rtificial muscle tubes, a dynamic model of the artificial muscle actua tor is formed and exploited to derive a full dynamic model for the man ipulator system. By applying the VSS approach and the full dynamic mod el of the manipulator, a robust tracking control strategy is developed for such manipulator systems. Asymptotic stability of the closed-loop tracking error system is proven by means of the Lyapunov methodology. Some numerical case studies are provided to illustrate the performanc e of the control approach.