Design of a Variable Stiffness Actuator Based on Beam Flexure and Bistable Mechanism

Variable stiffness actuator (VSA) is important for its contribution to improve the robot's performance and safety, especially in case of interactions between human and uncertain environments. In this paper, a VSA is designed based on beam flexure as well bistable compliant crank-slider mechanism. The beam flexure and the bistable mechanism are connected by a slider, offering a variable supporting force. The stiffness is not influenced by the joint position and the joint orientation, but associated with the distance from the slider to rotating center of variable stiffness mechanism. This paper illustrates the operating principle, with a mechanics model, and validates the characteristics by experiments.