Adaptive high‐order sliding mode controller‐observer for MIMO uncertain nonlinear systems
Abstract
In this paper, an adaptive high‐order sliding mode controller‐observer is proposed for multi input–multi output uncertain systems with application to robotic manipulators. Firstly, a type‐2 Takagi‐Sugeno fuzzy system is used to model the original system. Next, with the unavailability of velocity measurement, a fuzzy high‐order sliding mode observer is designed to estimate both the joint velocities and uncertainties. Moreover, based on a super twisting second‐order sliding mode, the proposed robust controller generates smooth control and guarantees finite‐time convergence to the third‐order sliding set with respect to the sliding variable by keeping second‐order sliding mode constraint. The controller gains are generated based on an adaptive estimation scheme without overestimation. The finite‐time stability of the suggested controller is proved by using an homogeneous and strict Lyapunov function. Finally, the obtained simulation results for two‐link robot manipulators demonstrate the effectiveness of the proposed controller.