Human interactive motion of redundant manipulator by virtual nonholonornic constraint

Abstract

Nonholonomic constraint offers people an intuitive way to handle systems. As an application of this human ability, we set a virtual nonholonomic constraint on the end-effector of a robotic manipulator. The operator holds its end-effector and moves it as if he/she was using a shopping cart or a barrow. We use anisotropic impedance control to realize the constraint. The end-effector is able to rotate and move toward itself, but not vertically. A 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 a vibrating hand working on complex jobs like manufacturing and surgery.