A Novel Cam-Based Variable Stiffness Actuator: Pitch Curve Synthetic Approach for Reconfiguration Design

Abstract

Variable stiffness actuators (VSA) have attracted much attention because of their potential for human-like interaction behaviors. This paper devotes to improving the VSA’s versatility. VSA with different characteristics can be obtained by shape reconfiguration of its internal driving cams. The proposed VSA mainly includes a variable stiffness module and a cam-based driven module. A common node connects the two modules. It is placed in the common grooves of the dual cams. Kinematically, the radial position of the node can be changed for stiffness adjustment by cam differential motion. Mechanically, the driven force on this node can be resolved into two orthogonal directions by cam groove, one for stiffness adjustment and another for position balance., The paper establishes the analytical relationship between the pressure angle of the cam pitch curve, stiffness adjustment speed and accuracy, and load distribution. Furtherly, the pitch curve synthetic approach for VSA reconfiguration is provided. A special cam shape with a favorable load distribution is proposed to verify the method. The correctness of the design was effectively proved by experiments in the virtual model and physical prototype.