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Objectives: The goal of this project is to design, fabricate, and test a system for accurately assessing balance and mobility impairments. Using new technology, a fast, small, lightweight, wearable digital system is being developed to replace older analog sensor technology.
Clinical Relevance: A wearable accelerometric motion analysis system provides a means of diagnosing and reducing risk of falls, formulating individualized therapies, and monitoring patients' progress. Video analysis and force plate systems, the current quantitative balance and motion assessment methods, are expensive and are not portable. The system is expected to be essential to new clinical proposals for prevention of pressure sores and mobility therapy for Parkinson's disease.
Methods: The next generation wearable accelerometric motion analysis system measures linear accelerations in the +/- 10g range using four sets of triaxially mounted digital accelerometers. The accelerometers are mounted in both corners of an eyeglass frame and the left and right sides of a waist belt to measure head and trunk accelerations, respectively. The digital accelerometers' output pulse frequencies are proportional to the measured accelerations and are fed into twelve 16-bit counters. At the end of each sample interval the counters transfer their data to internal registers. These registers are read by the embedded computer system, transformed to milli-gs, checked for thresholds in value, slope, magnitude, and angle, and stored onto a PCMCIA flash memory card for post-processing analysis. The system also provides for sensory (visual, tactile or speech) output triggered by timing and/or threshold criteria, and for communication with an operator unit and/or other sensors and data processors via serial radio-frequency links.
Results: Currently a functional desktop version of this system has been developed and successfully bench tested. A wearable version is being fabricated and will be tested using the same methods as the original system for sensor drift, sensitivity, misalignments, etc. Data from this new system will be compared to the first generation database and to conventional measures of human body motion including force platforms and goniometry.
Conclusions: The technology used in this effort allows for great versatility in the device. The EPROM- based programmability allows the device to be customized for specific activities with minimal changes to the hardware.
Acknowledgments: VA Merit Review (E2182DA)