Compliance Control of a Novel Variable Stiffness Actuator

In this paper, a novel type of variable stiffness mechanism is established, and the influence of different design variables on the stiffness of the system is analyzed. A dynamic model composed of motor, VSM and preset load is established to control its position and torque. Four different classical controllers are designed and simulated. Through analyzing its frequency domain characteristics, it is found that there is a problem of small stability margin in its control performance. The system state space equation is established, a LQR state space controller is designed, which uses all the states of the system and achieves the best performance in the linearized model. Finally, through zero-torque experiment, the motor tracking motion is realized, which lays the foundation for the future application of exoskeleton.