Safe Arm Using Compliant Hybrid Joints for Mobile Manipulators in Human-Symbiotic Environments

Safe Arm Using Compliant Hybrid Joints for Mobile Manipulators in Human-Symbiotic Environments

  In this paper, a safe arm with compliant hybrid joints for human-friendly service robots is presented, which realizes human safety, absorbing impact force, and 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 human, the arising impulse force is attenuated effectively by the physical model, which is developed with hybrid joints and 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 as well.