Adaptive tracking controller of DC servomotors

An adaptive tracking controller that eliminates steady-state error is presented. The design uses a variable-structure system with a nonlinear switching surface. The proposed scheme was applied to a DC servomotor system whose Coulomb friction value was changed by a dynamometer. The transient performance of this robust and simple system was improved by the nonlinear sliding surface. The experimental results clearly show that the tracking control scheme has the advantages of robustness, accuracy, and fast response without overshoot. However, the nonlinear switching surface requires more calculation time than a linear switching surface