Design of a Lever-type Deflection Angle Decoupling Variable-stiffness Joint Based on Involute Contoured Cam

Current lever-type variable-stiffness joints suffer from the coupling between stiffness and deflection angle. To overcome this limitation, a variable-stiffness joint design scheme is proposed. Firstly, a structure scheme of the adjustable-pivot lever mechanism is proposed. Herein, the joint stiffness is proved to be independent of deflection angle by analyzing the statics model. Furthermore, an involute cam mechanism is designed to adjust the pivot position of the lever mechanism, achieving a linear relationship between the cam angle and the pivot position. This design reduces the difficulty in adjusting the joint stiffness. Finally, a prototype of variable-stiffness joint is designed and manufactured, and the stiffness characteristics of the prototype joint and the relationship between stiffness and deflection angle are simulated and tested respectively. The feasibility of the variable-stiffness principle and the decoupling between stiffness and deflection angle are verified.