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A Virtual Headstick for People with Spinal Cord Injuries

Shoupu Chen a1, Tariq Rahman a1, Richard Foulds a1, Edwin Heredia a2 and William Harwin a3
a1 Center for Applied Science and Engineering, University of Delaware/Alfred I. duPont Hospital for Children, Wilmington, DE 19899, USA
a2 Thomson Consumer Electronics, Corporate Innovation and Research, Indianapolis, IN 46206, USA
a3 Department of Cybernetics, University of Reading, Reading RG6 6AY, UK


This paper presents a virtual headstick system as an alternative to the conventional passive headstick for persons with limited upper extremity function. The system is composed of a pair of kinematically dissimilar master-slave robots with the master robot being operated by the user's head. At the remote site, the end-effector of the slave robot moves as if it were at the tip of an imaginary headstick attached to the user's head. A unique feature of this system is that through force-reflection, the virtual headstick provides the user with proprioceptive information as in a conventional headstick, but with an augmentation of workspace volume and additional mechanical power. This paper describes the test-bed development, system identification, bilateral control implementation, and system performance evaluation.

Key Words: Assistive robotics; Head-control; Proprioception; Tele-manipulators; Force-reflection; Master-slave manipulation systems; Man-machine systems; Force-feedback control; System identification; Fitts' law.