Human interactive motion of redundant manipulator by virtual nonholonomic constraint

Nonholonomic constraint offers people intuitive system being easy to handle. It is just easy for people to ride a bicycle, drive a car, or handle wheel barrow, which geometrically involve nonholonomic constraint though these actions require to get used to do. As an application of this human's ability, we set virtual nonholonomic constraint at end-effector of robotic manipulator. The operator holds its end-effector and moves it as if he/she was using a shopping cart or a barrow. This work assumes the people, especially old generation and children, to use robots without any specific skills or knowledge on the robotic system. The robotic system should be easy to understand and expect on how it will move next. In this paper, we use unisotropic impedance control to realize the constraint. End-effector is able rotate and move toward itself, but not vertically. Reaction torque observer is applied to recognize the force by the operator in order to make the system sensorless. This system offers several applications, for example, to correct vibrating hand working on complex jobs like manufacturing and surgery.