Design and Analysis of a Novel Compliant Actuator With Variable Stiffness by Spring Pretension Adjustment

• Published in: IEEE access Vol. 11; pp. 108211 - 108221
• Main Authors: Zhao, Youlei, Liu, Junqiang, Li, Li, Xu, Yapeng
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuators; Design engineering; Force; Human engineering; Hysteresis motors; Joints; Mechanism design; Proportional derivative; Rails; robotic joint; Robots; Springs; Stiffness; Torque; variable spring angle mechanism; variable stiffness actuator
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2023.3321028

Variable stiffness actuators (VSA) are an emerging advanced driving method for robotic joint in physical human-robot interaction scenarios. This paper proposes a VSA based on adjusting the pre-tightening force of the driving ropes by rotating the linear springs to change the angle of its axis relative to the input frame. By adjusting the spring angle within a small relative rotation angle stroke, the angle between the spring axis and the transmission rope can be changed, thereby achieving rapid stiffness adjustment in a large range. The characteristics analysis shows that the proposed VSA has good stiffness adjustment independence. The mechanical design scheme of the VSA is introduced in detail. Simulations based on a proportional derivative (PD) controller demonstrated the effectiveness of the design.