Design and Impedance Control of the Integrated Rotary Compliant Joint

摘要

In order to make robots adapt the complex work environments and guarantee safety during physical human-robot interactions, an integrated rotary compliant joint with active and passive compliance is proposed. Passive compliance is derived from a designed series elastic actuator (SEA) equipped between the harmonic reducer and the load link. The SEA is mainly composed of linear springs so that the compliant joint may minimize large forces from collision and store energy in the elastic elements. Meanwhile, the variable stiffness model of the joint is established. The torque of the compliant joint is obtained by measuring the deflections between motor and link through an encoder but a torque sensor, furthermore the obtained torque is used as feedback to realize force closed-loop. The dynamic model of the designed integrated compliant joint is established, and the active compliance is achieved by impedance control. To ensure safety, the joint torque is monitored to a threshold to adjust the desired trajectory. The experiment indicate that, the designed integrated compliant joint can provide enough effective compliance during the human-robot interactions, which meets the requirements for the safety of robot.