Since 1989, the VA Palo Alto Rehabilitation R&D Center has been developing a Wearable Accelerometric Motion Analysis System with the goals of identifying patterns of human body movement that accompany loss of balance before a fall occurs, warning of pre-fall behavior, and if necessary, signaling that the wearer has fallen. Used as an adjunct to physical or occupational therapy, the WAMAS can act as a surrogate therapist, monitoring a patient's performance and providing cues as needed to encourage compliance with a course of therapy.
The basic concept is that the measurement system travels with the user, rather than requiring the user to come to a specialized facility. The WAMAS occupies a niche in the spectrum of tools for diagnosis and therapy of movement disorders midway between observational "eye-ball" estimation of risk of falling and consequent injury, and expensive laboratory-based gait analysis available only at a few locations.
The WAMAS instrument differs from laboratory-based quantitative motion analysis in being wearable during everyday activities and unrestricted with regard to where it is used. Portable accelerometric dataloggers or "actimeters" now on the market simply count the number of times acceleration values cross a threshold at only one location on the body; increasing use of such simple devices implies an unmet need for better documentation of body motion. By obtaining a "rich data set" using multi-axis sensors on multiple body segments (e.g.: on a belt to measure whole-body movement and on eyeglass frames to measure head movement), the WAMAS allows identification and quantification of much more complex motions. Analytical methods for WAMAS data differ from both conventional gait labs and "actimeters"; the WAMAS uses pattern recognition algorithms to detect clinically significant events, treating "body language" in much the same way as computer speech recognition.
The WAMAS hardware is designed to be easily upgraded as new technology becomes viable, without invalidating past data records or processing programs. In particular, we anticipate converting sensor connections from wired to wireless, for less obtrusive mounting on the body and in the environment. We have added output capability to provide audible, visual or tactile feedback to the WAMAS wearer, to help overcome mobility disorders such as Parkinson's Disease, and to encourage compliance with prescribed therapeutic exercise, among other applications.
Another unique feature of the WAMAS project is the library of motion data recorded in laboratory and clinical settings from more than 240 subjects of a broad range of ages and movement capabilities; this library can be used to establish norms for comparison with new data and to test new recognition algorithms, without the need to conduct more clinical trials.
For several reasons, we feel that the time is ripe for this technology to move from research into the commercial sector:
We have identified a number of medical and non-medical applications for WAMAS technology. Initial medical uses are for quantitative gait and balance diagnosis outside the laboratory, in clinics, nursing homes and residences, both in stand-alone form and as part of a telemedicine system. Utility in monitoring and therapy of Parkinson's disease, hip arthroplasty, neuropathic and pressure-sore prone patients can be anticipated. Non-medical applications include assessment and training of complex exercise and athletic activities (hurdles, vaulting, gymnastics) as well as simpler ones like golf and running, prevention of occupational repetitive motion injuries, or any time-sensitive segmental motion to be encouraged or inhibited.
Aspects of the hardware and operating software were disclosed in April, 2001, to the VA General Counsel's Office (case numbers #01-012, 01-013 and 01-024). Per an Inter-Institutional Agreement between VA and Stanford University, in September 2001, management of intellectual property was assigned to Stanford's Office of Technology Licensing (docket numbers S00-213, 214, and 215). Stanford's Medical Device Network is cooperating in the effort to find industrial partners/licensees.
Opportunities for collaboration with industrial partners include outright licensing to an existing or newly formed corporation, multi-partner arrangements with separate manufacturers and distributors, and Cooperative R&D Agreements to continue VA research and clinical testing.
For details on WAMAS hardware development and application to solving problems in diagnosis and therapy of mobility disorders, see reports and presentations posted on Eric Sabelman's webpage.