Real-Time Area-Based Haptic Rendering for a Palpation Simulator

In palpation procedure, medical doctors push and rub the organ's surface and they are provided the sensation of distributed pressure and contact force (reflecting force) for discerning doubtable portion. This paper suggests a real-time area-based haptic rendering model to describe distributed pressure and contact force simultaneously and present a haptic interface system to generate surface property in accordance with the haptic rendering algorithm. We represent the haptic model using the shape-retaining chain link (or S-Chain) framework for a fast and stable computation of the contact force and distributed pressure from a volumetric virtual object. In addition, we developed a compact pin-array type of tactile display unit and attached it to PHANToMTM haptic device to complement each other. In order to evaluate the performance of the proposed scheme, related experiments have been conducted with non-homogenous volumetric cubic objects consisting of approximately 500,000 volume elements at a haptic update rate of 1000 Hz. The experimental results show that compared to the point-contact the area-contact provides the users with more precise perception of the shape and softness of the object's composition, and that our proposed system satisfies the real-time and realism constraints to be useful for virtual reality applications