Motion control of a semi-mobile haptic interface for extended range telepresence

This paper presents the control concept of a semi-mobile haptic interface for extended range telepresence that enables the user to explore spatially unrestricted target environments even from a small user environment. The semi-mobile haptic interface consists of a haptic manipulator mounted on a large grounded Cartesian robot, the prepositioning unit. The prepositioning unit is controlled in such a way that the haptic manipulator is kept off its workspace limits. At the same time, the control algorithm allows the optimal utilization of the available space in the user environment and guarantees the safety of the user. The proposed control method is based on the position and velocity of the end-effector and also takes the position of the user into account. Moreover, it is robust against noisy measurements of the user position or outliers due, for example, to occlusions in the tracking system. Experimental results show the suitability of the proposed control to provide haptic interaction in extended range telepresence.