金沢大学大学院自然科学研究科知的システム創成金沢大学工学部The measurement of physical activity is one of key subjects in fields like rehabilitation and gerontology. Moreover, ambulatory monitoring of changes in human posture in daily life will provide useful information for evaluating results obtained by Holter-type ECGs or ambulatory blood pressure monitors. From this viewpoint, several instruments have been developed which can estimate physical activity in daily life. For example, the Actigraph is a wrist-worn commercially available activity monitor that measures the movement of the subject\u27s hand, and has been widely used for evaluating sleeping disorder. Another example is a system that measures acceleration of the thigh or waist using an accelerometer or gyroscope for rough estimation of a subject\u27s behavior during daily life. However, these instruments have limitations for detailed analysis of posture change and cannot be used for the simultaneous measurement of walking speed, which is a useful index for evaluating the independence of elderly individuals. Taking these factors into consideration, we developed a new sensor system that accurately measures human posture together with walking speed. The system is composed of three accelerometers and one gyroscope. The accelerometers are for posture measurement, and are attached to the subject\u27s waist, thigh and leg, respectively, so as to measure the angle in terms of gravitational direction of each part. The gyroscope measures the change in thigh angle when walking in order to estimate walking speed. The accuracy of the system for posture and walking speed measurements was experimentally evaluated using ten healthy male subjects. According to the results, it was clearly demonstrated that, using the system, human posture in the sagittal plane (±180deg) and walking speed (0.2 m/s-2.0m/s) can be measured with reasonable accuracy, and that the system is a useful means for analyzing human activity during daily life
