Application of Sliding Mode Control to Robotic Systems

Abstract

Most research and applications in robot control deal with electrically actuated robots (this is generally due to ease of their use and low cost) but use of pneumatic and hydraulic systems is increasing. The latter are used in robotic systems when large forces and direct drive possibilities with high capabilities are required. This justifies their extensive use in industrial applications. This chapter deals with the application of sliding mode control and passive feedback systems for mechanical systems encountered in robotics involving pneumatic and hydraulic actuators. We show that sliding mode control is a viable approach for such systems. Simple examples are studied first in order to introduce a methodology for this kind of control techniques. The mathematical model of a hydraulically or pneumatically actuated system is highly nonlinear and time-varying. Several energy conversions are present (electro-mechanical to hydraulic or pneumatic pressure and then to mechanical motion). Generally the control of such systems has been first based on classical or PID feedback approaches [1, 2]. Next the intent was to enhance the control by use of state space design and adaptive control