Sliding mode control of direct drive robot using fuzzy disturbance estimation

This paper presents a decoupled continuous sliding mode controller suitable for use in the motion control of uncertain nonlinear systems, as direct drive robots. A disturbance compensation problem is solved by a fuzzy logic system (FLS) with adaptive positions of output fuzzy membership functions. The stability of the adaptation procedure is given via the Lyapunov stability theorem. FLS is divided into three fuzzy subsystems according to the physical properties of robot dynamics. This structure results in a clear fuzzy rule base with a reduced number of rules and enables systematic inclusion of linguistic knowledge. Performance of the proposed method is illustrated by experimental results in a motion control task and positioning task with varying payload on a three degree of freedom direct drive robot.