Control Synthesis and ISS Stability Analysis of Dual-User Haptic Training System Based on S-Shaped Function

The controller design and stability analysis of a dual user training haptic system is studied. Most of the previously proposed control methodologies for this system have not simultaneously considered special requirements of surgery training and stability analysis of the nonlinear closed-loop system which is the objective of this paper. In the proposed training approach, the trainee is allowed to freely experience the task and be corrected as needed, while the trainer maintains the task dominance. A special S-shaped function is suggested to generate the corrective force according to the magnitude of motion error between the trainer and the trainee. The closed-loop stability of the system is analyzed considering the nonlinearity of the system components using the Input-to-State Stability approach. Simulation and experimental results show the effectiveness of the proposed approach.