9860393 Large tracking volumes are needed for many virtual environments yet current commercial head-trackers, based mainly on magnetic technology, allow accurate performance only in a small volume. This Small Business Innovation Research Phase I project from Resolution Displays, Inc. seeks to design, build, and demonstrate a head-tracker capable of measuring the positions (in six-degrees-of-freedom) in a practically unlimited volume. Current head-tracking technology is dominated by magnetic field generation and detection techniques. Magnetic head-trackers work well in a small volume (within a radius of 30 inches from the source) but the performance degrades sharply as a function of distance from the source. A small tracking volume also makes it difficult to accommodate simultaneous users. The proposed head-tracking system uses an innovative technique that allows the use of a large number of ultrasonic transducers thus greatly expanding the three-dimensional range at which measurements can be made and mitigating line-of-sight problems. In addition, the use of inexpensive piezo ultrasonic transducers and the continually decreasing price of powerful digital signal processors makes it possible to devise a low cost product This project has the potential to make an important contribution to the field of computer simulation technology. In virtual reality applications, poor accuracy manifests itself as jitter of the image in the head-mounted display (HMD). Resolution Displays anticipates the technical specifications of its proposed head-tracking technology--translation jitter of 0.01 inches rms maintained within this volume with an update rate up to 200 Hz--to enable an increase in tracking volume so as to greatly expand the number of new computer simulation applications using virtual environments and to enable old applications to perform better.
