2019 年 13 巻 4 号 p. JAMDSM0069
An inertial measurement system for estimating gait parameters indicating cognitive impairment is developed for use during large-scale health checkups. Current health checkups conduct a 10 m fastest gait examination to assess signs of cognitive impairment and physical performance. Earlier methods require examiners to follow a subject and measure the gait time using a stopwatch. The method proposed herein reduces burdens on examiners. Several gait parameters in addition to the gait time of many subjects can be measured simultaneously and quantitatively from three-dimensional foot movements estimated using inertial sensors comprising two accelerometers and two gyroscopes with different measurement range attached to both feet. Gait parameters derived from the inertial sensor are gait time, stride length, gait cycle, gait velocity, toe angle, toe height, and the percentage of swing phase. The gait condition, such as walking or running, is distinguished from the moment of toe off and heel contact of both feet. In all, 1406 subjects with ages of 19-93 years old were given instructions to walk at their highest velocity on a straight 16-m-long walking course. Mini-Mental State Examination (MMSE) is conducted on subjects. The score is used as a reference valuation of the cognitive impairment level. Experimental results show that the proposed measurement system provides equal performance to that obtained using a stopwatch and improves correlation between the MMSE score and the fastest 10 m gait time of subjects who did not run. Furthermore, it is confirmed that the proposed measurement system using inertial sensors can quantitatively provide spatiotemporal gait parameters to evaluate the physical performance in a short time during the large-scale health checkups.
