Tactual displays provide the sensations of touching computationally simulated objects.
Algorithms have been developed to provide haptic rendering of three-dimensional (3D) objects in virtual (that is, computationally simulated) environments. The goal of haptic rendering is to generate tactual displays of the shapes, hardnesses, surface textures, and frictional properties of 3D objects in real time. Haptic rendering is a major element of the emerging field of computer haptics, which invites comparison with computer graphics. We have already seen various applications of computer haptics in the areas of medicine (surgical simulation, telemedicine, haptic user interfaces for blind people, and rehabilitation of patients with neurological disorders), entertainment (3D painting, character animation, morphing, and sculpting), mechanical design (path planning and assembly sequencing), and scientific visualization (geophysical data analysis and molecular manipulation).
Some elements of the collision-detection algorithms used in computer graphics can be used in computer haptics. For example, haptic-rendering algorithms can easily take advantage of space-partitioning, local-searching, and hierarchical-data-structure techniques of computer graphics to reduce the amount of computation time needed to detect collisions. However, mere detection of collisions as in computer graphics is not enough because how a collision occurs and how it evolves over time are factors that must be taken into account to compute interaction forces accurately. Going beyond computer-graphics collision-detection algorithms, it is necessary to develop algorithms according to a client-server model to provide for synchronization of visual and haptic displays in order to make update rates acceptably high. For example, by use of multithreading techniques, one can calculate the contact forces at rate of 1 kHz in one thread while updating visual images at 30 Hz in another thread.
This work was done by Cagatay Basdogan of Caltech, Chih-Hao Ho of Cambridge Research Associates, and Mandayam Srinavasan of MIT for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Information Sciences category.
This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393-3425. Refer to NPO-21191.
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Algorithms for Haptic Rendering of 3D Objects (reference NPO-21191) is currently available for download from the TSP library.
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