Proportional-derivative sliding mode control for mobile lifting and transferring robot

Abstract

The task of lifting and transferring mobility-impaired patients demands stringent standards for safety and stability. However, most current assistive devices operate manually and lack an active sway suppression mechanism, easily leading to payload oscillations and inducing psychological anxiety in patients. To address this issue, this paper proposes an autonomous mobile patient lifting and transferring system, consisting of a differential-drive mobile robot combined with a load suspension mechanism, capable of autonomous trajectory tracking. In the proposed model, a PD-SMC (Proportional-Derivative Sliding Mode Control) controller is utilized. This method simplifies the structure of the traditional sliding mode controller while maintaining superior disturbance rejection against uncertainties such as variations in patient mass and exogenous disturbances. The results demonstrate that the PD-SMC controller generates smooth control signals, forcing the state trajectories to converge rapidly, thereby enabling the system to accurately track the moving trajectory and completely suppress payload oscillations. This proposed approach not only improves operational efficiency but also ensures maximum safety and provides a smooth experience for the patient.