Optimizing a Fuzzy Equivalent Sliding Mode Control Applied to Servo Drive Systems

Positioning accuracy of servo drive systems is very important for tasks that require precision. From the control point of view, servo drive systems are complex due to their non-linear time-varying dynamics. Most of the control strategies applied to these systems either introduce undesirable chattering in the response or suppress it at the cost of producing large tracking errors. In this work, an equivalent sliding mode control based on fuzzy logic is applied to a servo system. The fuzzy membership functions of the switching function are optimized in order to improve the control robustness and to obtain accurate tracking at the same time. Simulation results show that this soft computing control proposal can effectively eliminate the chattering and reduce the tracking error for servo drive systems. It has been compared to conventional sliding mode control and sliding mode control with boundary layer with encouraging results.