Sensitivity Analysis of Structural Clearances on the Performance of a Lever-Based Variable Stiffness Actuator

Variable stiffness actuator (VSA) can perform a safely environment-robot interaction on the basis of its inherent compliance and adjustable stiffness. However, its performance of stiffness and position could be notably affected by the structural clearances existing within the stiffness regulation mechanism. In this paper, the effects of structural clearances within the stiffness regulation mechanism on the performances of stiffness and position are studied, and several guidelines for the manufacture of lever-based VSA are achieved. The structural clearances between the rollers and cam-based profiles are analyzed and several simulations are carried out to evaluate its effects on the performance of stiffness. Then the effects of structural clearances within the lever mechanism on the position accuracy are studied in detail. The results indicate that, the clearances existing within the parts involving the movement of pivot should be paid much more attention to when pursuing better accuracies of stiffness and joint position.