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Objective and Significance: The purpose of the Wearable Accelerometric Motion Analysis System (WAMAS) is to create a means for real-time quantitative body motion analysis in non-laboratory settings. The WAMAS occupies a niche in the spectrum of tools for diagnosis and therapy of movement disorders midway between observational estimation of risk of falling and consequent injury, and expensive laboratory-based gait analysis . It can provide unattended on-site quantitative records of balance status in the homes of those undergoing outpatient treatment; it is also suitable for use in outlying clinics remote from central laboratories. If physical or occupational therapist time with each patient is limited, the motion analysis system can act as a surrogate therapist, monitoring a patient's performance and compliance with a course of therapy. The wearable accelerometric instrument has utility, first, as a diagnostic tool to quantify hitherto qualitative measures of balance; second, as a biofeedback device during therapy; and third, as a fall-prevention aid -- what might be called a "balance orthosis" -- for institutionalized and community-living fall-prone elderly veterans.
Methods and Results:
TechnologyThe basic WAMAS consists of two small 3-axis sensors attached to both corners of eyeglass frames to measure head motion, and two more above the hips on a belt at the waist. Also on the belt is a self-contained data acquisition package which digitally records the 12 sensor outputs at 20 to 200 samples per second. An hand-held or wearable remote control is used to command the wearable unit so the patient or test subject is unencumbered by cables. Two versions of the WAMAS have been constructed, the first using electronic technology available in 1989. A second generation design based on 1997 technology has improved the size, speed and power consumption of the equipment; it uses a field-programmable logic front-end, a DOS-based computer and PCMCIA memory cards, compared to the analog front-end, BASIC language and serial data download of the first generation.
Research: We have locally tested gait and balance in populations of normal young and elderly subjects, participants in a study of efficacy of oral gingko biloba, and patients with stroke, hip arthroplasty, Parkinson's Disease, peripheral neuropathy and high risk of pressure sores. Through a multi-center collaboration arrangement, non-local participants have been loaned the WAMAS equipment and supporting software, after agreeing to share data so as to expand the motion pattern database, assist each other with interpretation, and credit the VA in publications.
Technology Transfer: In addition to publications by researchers who have used the WAMAS, formal technology transfer activities have included:
Marketing studies done by students at three business schools -There are three classes of potential purchasers: the high end is the fully-equipped gait laboratory,; next is the small clinic, hospital or nursing home, which now does large numbers of balance assessments using cheap, imprecise methods; third is the fall-prone or occupationally-injured user who is trying to protect him/herself from further injury.
Patent searches - most self-contained accelerometer-based devices measure only a single body segment (e.g.: #5724265 "System and method for measuring movement of objects" [1998] located on the foot).
Sending notices of licensable technology to 50+ companies in the fields of: (1) fall prevention in nursing homes and other clinical settings, (2) physical therapy equipment, (3) gait laboratory instrumentation, and (4) mechanical vibration measurement. . Roughly 10% responded; one company proceeded until an upper management decision to develop an add-on to an existing product similar to the WAMAS.
Responding to inquiries from commercial firms interested in the WAMAS technology - These occur about twice a year, but usually yield no action by the prospective Cooperative R&D Agreement (CRADA) partner. Tanner Research, a firm which developed an algorithm for gesture recognition under DARPA sponsorship, has submitted a SBIR to apply this method to WAMAS data analysis.
Submission of product information to Stanford University Office of Technology Licensing (OTL), which in February, 1999, signed a 5-year CRADA to facilitate development of VA-sponsored research, particularly by accelerated contact and negotiation with potential industrial partners.
Discussion with Stanford Medical Device Network (MDN), which exists to encourage and facilitate invention, patenting and early stage development of medical devices.
Conclusions: Since the WAMAS has a broad range of potential applications, commercial development largely depends on enlisting the support of a company willing to explore a number of niche markets. New Rehabilitation R&D Center affiliation with the Medical Device Network may help to spread the word about the advantages to companies of SBIR cooperation with RR&D and to overcome a reluctance by companies to commit resources to CRADAs with VA. Once we reach the point of negotiating a CRADA, we will decide which commercial organization(s) are granted licenses or CRADAs based on our judgment of (1) the stability and capability of the company to carry out its commitment to the VA, and (2) the company's enthusiasm for expanding its market into wearable, non-laboratory-based motion analysis.
Funding Acknowledgement: Supported by VA Rehabilitation R&D Merit Review projects E601-RA, -2RA, -3RA, E2182-DA, E2153-TC. We thank Betty S. Troy for her assistance with technology transfer.