Development of hybrid joints for the compliant arm of human-symbiotic mobile manipulator

Abstract

This paper presents a safe arm using compliant hybrid joints for human-friendly service robots, which realizes human safety, absorbs impact force, and provides task fulfillment. The robot is composed of links covered with soft materials and hybrid joints, which can be put into active or passive mode as needed. In an unexpected or expected collision with a human, the arising impulse force is attenuated effectively by the proposed physical model, which is developed with the hybrid joints and the soft covering. Owing to the displacement of the links when the joint is passive, a recovery control algorithm has been developed for the end-effector to maintain its desired task position after the collision. The force attenuation property has been verified through collision experiments in that the capability of the proposed passive arm in overcoming the limitations of active compliance control has been demonstrated. Simulation results also showed that the proposed control method is useful for robot's task fulfillment.