Collision-Tolerant Control for Hybrid Joint based Arm of Nonholonomic Mobile Manipulator in Human-Robot Symbiotic Environments

a human-symbiotic safe mobile manipulator with nonholonomic constraint is described to realize human safety, impact force absorbing and task fulfillment. The robot consists of an arm 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 formed with the hybrid joint and the soft material. Owing to the displacement movement of the link 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. Simulation and experiment results confirm that the proposed physical model is suitable for robot working in the human-robot symbiotic environment and the control method are useful for robot’s task fulfillment.