Fixed-time integral sliding mode control of a high-order nonlinear system

This paper investigates the problem of fixed-time tracking control for a class of high-order nonlinear systems with matched disturbances. A novel continuous fixed-time sliding mode disturbance observer is first proposed to accurately estimate the external disturbances. Then, a new integral high-order sliding mode (IHOSM) surface is proposed in the sense of fixed-time stability by the bi-limit homogeneous method. Subsequently, utilizing the disturbance estimation information, an IHOSM-based fixed-time control scheme is proposed which can enforce the closed-loop control system reach the real sliding mode surface. Meanwhile, it is applied to an error dynamic system of a wheeled mobile robot to achieve fast accurate trajectory tracking. Finally, the comparative experiment results demonstrate the effectiveness and superiority of the proposed control approach.