Design of A Variable Stiffness Actuator and Study on Its Variable Stiffness Characteristics

In this paper, the structural design of a variable stiffness actuator (VSA) is proposed, and the variable stiffness characteristics of the VSA are studied. The VSA is compact and can be used for humanoid robots. Firstly, the structure of the VSA is designed. Then the stiffness model of the structure is derived in theory and the dynamic simulation is performed in ADAMS. The stiffness results of dynamic simulation and theoretical calculation are highly consistent, which verified the correctness of each other. Finally, the influence of the curve equation of the worm gear disc on the stiffness of the system is studied: the radius of the curve is a function of the angle, and when the order of the curve equation is higher, the stiffness adjustment range of the system is wider. Under the premise of meeting the same stiffness requirements, when the order of the curve equation increases, the radius of the higher-order curve equation is only half of that of the lower-order curve equation, and a more compact VSA can be obtained. The results are of great significance to the prototype design, that is, without changing the main design dimensions of each component, the stiffness of the system can reach the design value simply by changing the order of the curve equation.