A New Method for Design and Control of Haptic Interfaces for Display of Rigid Surfaces

This paper addresses the often-cited problems associated with haptic display of rigid bodies or “virtual walls”. Traditional haptic interfaces employ an actuator directly coupled to the human operator that provides a force proportional to wall penetration distance and velocity. A new paradigm for design and control of haptic displays is proposed that utilizes a de-coupled actuator and pre-contact distance sensing to improve stability and response performance. Dynamic models of real human/rigid body contact and prior haptic display models are developed and compared with the proposed method. Errors in the force and energy transfer are identified and associated with virtual wall penetration distance, required in traditional virtual wall haptic models. Results of the simulation of the dynamic models are presented, identifying system force response errors attributable to delay, wall penetration, wall model spring constant, and wall model damping constants.