Impedance Synchronous Control for a Robot Multi-Motor Joint

Facing various external environment with increasing uncertainty, robots are challenged by the dynamic interactivity during the operation process. To tackle the problem, compliance control strategies are developed to tune the presented mass, damping, or stiffness properties of a robot. However, in large torque configurations, compliant robots driven by single-motor joints could have an inferior performance in stiffness control, system robustness, and cost. Thus, inspired by the biological mechanism which controls muscular stiffness using multiple muscle fasciculi, this paper studies a multi-motor driven double pendulum based on the impedance control strategy. In contrast to single-motor joints, multi-motor joints have advantages in the flexibility of variable rigidity, the simplicity of torque control, and the large ratio of output torque versus weight/cost. Simulations compare the performance between the single-motor and the multi-motor cases on response time, route of the end actuator, and energy cost. The results indicate the superiority of the robot arm with multi-motor joints over the single-motor case.