Haptic display of contact location

This work presents a new haptic device that integrates contact location feedback with grounded point-force display. The system consists of a thimble-based mechanism attached to the endpoint of a Phantom/spl reg/ robotic arm. Contact location is rendered using a small tactile element that moves along the length of the user´s fingerpad. The Phantom/spl reg/ robot applies reaction forces to the user´s finger through this tactile element, bringing it into and out of contact with the user as required. Force and contact location are thus displayed concurrently. During operation, the system continually adjusts the position of the contact element based on finger motion and expected or actual contact with the two-dimensional virtual environment. The finger is modeled as an arc segment, and the environment as a series of lines and arcs. Haptic rendering is driven by a virtual finger proxy, employing collision detection and collision anticipation algorithms. A series of human subject tests compared contact location feedback to standard force feedback. Subjects completed a contour following task in less time and with fewer failures when contact location information was available. The system´s success indicates a simple yet promising new avenue for the design of haptic displays.