A gain scheduled sliding mode control scheme using filtering techniques with applications to multilink robotic manipulators

In this paper, a gain scheduled sliding mode control (SMC) scheme is propos ed for tracking control tasks of multilink robotic manipulators. In the new scheme, filtering techniques play the key role in acquiring equivalent con trol signals and scheduling the switching control gain automatically. Once the system enters the sliding motion, two classes of low-pass filters are i ntroduced to work concurrently for the purpose of acquiring equivalent cont rol, reducing the switching gain effectively, and as a result eliminating c hattering. By virtue of equivalent control theory, one class of filters is designed to capture the "average" profile of th switching quantity, which i s in proportion to the desired control input. Meanwhile, another class of l ow-pass filters is added to scale down the gain of the switching control. T he convergence property of the proposed control scheme is rigorously analyz ed in time domain and the frequency domain knowledge can be easily incorpor ated into the construction of the two classes of filters. Excellent trackin g performance is achieved with the direct manipulation of switching control input using filtering technology and with the integration of both time dom ain and frequency domain system knowledge in controller design. [S0022-0434 (00)01604-X].