Nonadaptive and adaptive sliding mode control of robotic systems with a general sliding surface

In this paper, two different types of controllers, namely sliding mode control and adaptive sliding mode control are developed. A robotic variable structure control law consisting of a feedforward term plus a sliding mode term is presented. The feedforward term can either be selected as an estimation of the robot and actuator dynamics, or simply as zero. In the latter case, the control law is very simple and can operate with an unknown robot and actuator dynamics; the only information required are some bounds on parameters. These bounds can be estimated online resulting in adaptive sliding mode control. In all the control algorithms developed, a general sliding surface is utilized. The general sliding surface can represent a large class of sliding surfaces including those which are nonlinear and/or time-varying. As a special case, a reference model based sliding surfaces is investigated