Enhance Transparency of Force Feedback Interaction Series Mechanism by SMC Strategy

Abstract

To enhance the fidelity of virtual surgery, the force feedback interaction mechanism would simulate the force information in real surgery. This paper first introduces evaluation methods of fidelity, then it explores evaluation methods of force feedback fidelity, and put up the evaluation methods and indexes of force feedback fidelity. In rigid force feedback interaction mechanism, fidelity is mainly shown as transparency. It means the transfer function of the mechanism needs approach to 1, while friction, gravity, slip of the linear drive and other factors would affect transparency of the mechanism. This study introduces a 5-DOF (degree of freedom) force feedback series mechanism with long stroke. It discusses gravity compensation and simulation of typical virtual environment. It uses sliding mode control (SMC) to eliminate the effect of parameter variety, inaccurate modeling and other factors to improve system robustness. And it adds disturbance observer to the controller to eliminate gravity inaccuracy. Finally, it evaluates the enhancement of force feedback fidelity.