Estimation of human arm impedance in accordance with the master device types and gripping posture

In the teleoperation system, several researches are under investigating to carry out remote task effectively by measuring or estimating master operator's impedance and transferring the impedance to slave robot. However, previously proposed method provide equal amount of impedance for different axis so the method cannot guarantee transparency. Even if accurate amount of impedance are transmitted to each orthogonal axis, there exists disadvantage that the overall teleoperation system becomes complicated. In this paper, a novel impedance estimation method is proposed by utilizing grasping posture of the master operator. The proposed teleoperation system is composed of 1-dof force sensor and a commercial haptic master device. Thus, for each posture when the operator grasps the master device, operator's impedance is transmitted to the slave robot for each direction. Two experimental tests were conducted to show its feasibility by measuring amount of operator's position change and impedance when two different kinds of master feedback force were transmitted to the operator. Moreover, during teleoperation task of opening a door, an experimental test was carried out to show the effectiveness of the proposed method by comparing constant impedance case and the proposed method.