A study on robustness property of sliding-mode controllers: A novel design and experimental investigations

The robustness property of sliding-mode controllers (SMC's) makes them attractive for industrial control applications. However, this property is valid only under ideal sliding-mode conditions. Additionally, practical SMC's are likely to exhibit high-frequency oscillations in the plant output, called chattering, and to excite unmodeled dynamics. A novel, chattering-free sliding-mode control algorithm design, based on Lyapunov stability criteria, is considered in this paper. The control algorithm developed is experimentally implemented on a direct-drive manipulator for various payload configurations. It is seen that the controller carries a certain amount of robustness property, the trajectory-following performance being only slightly affected by the changes in the payload. A comparison of the experimental results with those obtained by a well-tuned proportional-derivative control is also given.