Whole-Body Intuitive Physical Human-Robot Interaction With Flexible Robots Using Non-Collocated Proprioceptive Sensing

This letter presents a method enabling intuitive physical human-robot interaction (pHRI) with flexible robots using an end-point sensing device. The device is a passive serial chain of encoders and lightweight links, mounted in parallel with the manipulator. By measuring the deflection of the end-effector relative to the base, the whole body of the manipulator becomes a potential interaction interface, whether the compliance stems from the links or the joints. The proposed control scheme is a simple joint velocity control that only requires knowledge of the rigid body Jacobian matrix of the manipulator. The approach is validated both in simulation on a simplified model and experimentally on a physical 3-DoF flexible-link flexible-joint serial robot. The results indicate that intuitive pHRI is achieved, with interaction forces under 25 N even for tasks with high dynamics.