Design and performance analysis of reconfigurable variable stiffness compliant actuator

Compliant actuators can achieve safe interaction between robots and humans due to their inherent flexibility, and have strong environmental adaptability. To meet the requirements of exoskeleton robots for joint flexibility and variable stiffness characteristics, a reconfigurable variable stiffness compliant actuator was designed, which could achieve reconstruction by changing the geometric parameters, materials and quantity of elastic components, and achieve variable stiffness within an adjustable range by adjusting the radial preload. Firstly, based on the transmission principle of a zerolength frame four-bar mechanism, a stiffness mathematical model of the variable stiffness compliant actuator was established, and the influence of the number of flexible branches and the stiffness and preload of elastic components on the output torque and stiffness of the actuator was analyzed. Then, an ADAMS virtual prototype model of the actuator was established, and the statics performance simulation analysis was carried out to verify the correctness of the stiffness mathematical model. Finally, the dynamics model of the actuator was established and the transfer function of the dynamics system was obtained through Laplace transform. The frequency characteristics analysis results indicated that the stability of the compliant actuator was good. The designed compliant actuator had a small volume and small mass, which could be applied in the driving mechanism of wearable exoskeleton robots. The research results provide theoretical and technical references for the design of compliant driving joints in robots.