Trajectory Tracking Control for Intelligent Wheelchairs Based on Super-Twisting Sliding Mode Observer

As the rapidly rising number of elders and disabled people in China, intelligent wheelchairs become important to enhance the mobility for them. Many advanced technologies are integrated in intelligent wheelchairs, of which the stable and accurate motion control is the most important due to all the upper functions are depended on this. To solve the problems that the dynamic model of the intelligent wheelchair is difficult to establish accurately, and various disturbances in the movement process cause yaw to the high-precision trajectory tracking, a dual-loop trajectory tracking control method is investigated. Firstly, a virtual velocity controller is developed based on the trajectory tracking error. Then, a super-twisting sliding mode observer (STSMO) is constructed using the dynamic model to estimate the disturbance of the system, and the estimation error converges to zero in finite time. Based on this, a fast integral terminal sliding mode controller (FITSMC) is designed to accurately track the virtual velocity in finite time. Finally, the stability of the dual-loop system is guaranteed by the Lyapunov stability theory. Simulation results demonstrate that the recommended trajectory tracking control method has a faster response speed and stronger robustness.