The VA Palo Alto Rehabilitation R&D Center is developing a Wearable Accelerometric Motion Analysis System (WAMAS) with the goals of identifying patterns of human body movement that accompany loss of balance before a fall actually occurs, warning of pre-fall behavior, and if necessary, signaling that the wearer has fallen. As veterans age, they become increasingly at risk of injurious falls; hence, the need for a "balance orthosis" to help them maintain their independence. Three-axis silicon accelerometers are attached on eyeglass frames to monitor head motion, on a belt to detect trunk motion near the body's center of mass, or elsewhere on the body as needed. The present version of the WAMAS simultaneously samples 12 or more such accelerometers up to 112 times per second and stores data for later analysis. Subsequent generations will be capable of real-time analysis, as required for supplementation of a balance-impaired individual's own senses when performing therapeutic or daily living tasks. A remote control is used to command the computer, so that the wearer is completely unrestrained. The entire motion analysis system fits into a briefcase. 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. It can provide unattended on-site quantitative records of balance status in the homes of veterans 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.
Eric Sabelman (BS, MS - 1969, PhD - 1976, Stanford) is a biomedical engineer in the Musculoskeketal Systems Section at the VA Rehabilitation R&D Center in Palo Alto. He is also Consulting Associate Professor of Functional Restoration at Stanford Medical School. Previously, he has been an independent biotechnology consultant (Pro-Zooics Research, Menlo Park), Manager of Engineering Science at Collagen Corporation, and a life science fellow at NASA-Ames Research Center. He is principal investigator on VA projects on application of tissue engineering to nerve and connective tissue repair, and on application of micromachined motion sensors and wearable computers to diagnosis of balance disorders and prevention of falls. Interests include biomaterials, bioengineering education and bioethics.