Improving teleoperation system performance in the presence of estimated external force

Teleoperation systems have been developed in order to manipulate objects in environments where the presence of humans is impossible, dangerous or less effective. The presence of force signals plus position signals in the control scheme could effectively improve transparency. However, the main restriction is force measurement in some applications. A new modified strategy for estimating the external forces acting on the master and slave robots is developed. The main advantage of this strategy is that the necessity for force sensors is eliminated, leading to lower cost and further applicability. A novel control algorithm with estimated force signals is proposed for a general nonlinear bilateral teleoperation system with time delay. The stability condition in the teleoperation system with the new control algorithm is verified by means of Lyapunov stability analysis. The designed control algorithm guarantees stability of the teleoperation system in the presence of an estimated operator and environmental force. Experimental results confirm the efficiency of the novel control algorithm in position tracking and force reflection.