Design and implementation of a variable stiffness tensegrity-based compliant actuator

Abstract The variable stiffness actuator (VSA) excels at tasks that are challenging for traditional rigid mechanisms to perform. A novel variable stiffness tensegrity-based compliant actuator is proposed, following an analysis of the cons and pros of existing VSAs. The proposed actuator leverages a tensegrity structure to eliminate direct contact between rigid elements, thereby reducing the internal mechanical friction. This leads to low damping and compliant behavior. Additionally, it enables a wide range of stiffness adjustments and decouples rotational stiffness from the rotation angle by utilizing different variants of the mechanically adjustable compliance and controllable equilibrium position actuator (MACCEPA). The stiffness analysis of the single-joint actuator is presented and experimentally validated. This design is then extended to multi-joint mechanism applications, including serial mechanism configuration, wire-driven mechanism configuration, and direct-drive mechanism configuration. An evaluation of the structural characteristics of these three configurations is provided, offering different options for implementing VSAs. The conducted works could provide fresh insights into the field of VSA.