Physical Human-Robot Interaction through a Jointly-held Object based on Kinesthetic Perception

This paper deals with the problem of human-robot cooperative object manipulation for cases where the grasp position of the operator can change during task execution similar to human-human collaborative scenarios. In state of the art algorithms for cooperative object handling, a constant grasping position is considered for the operator. In order to accommodate the changes of the human grasping point in the control design, we do not depend on sensors on the operator's hand or on the object but we employ estimates obtained through a recursive least-squares estimator. The estimation algorithm uses only the measured wrenches obtained by a force/torque sensor located at the end-effector of the manipulator. We also propose a switching strategy for a damping controller based on the online estimates. Simulation results are provided in order to demonstrate the proposed method.