Page 32 - Mechatronics for Safety, Security and Dependability in a New Era

Ch04-I044963.fm Page 16 Tuesday, August 1, 2006 6:33 PM
Ch04-I044963.fm
16 16 Page 16 Tuesday, August 1, 2006 6:33 PM

Portable Measurement Device
(3-axis Accelerometer, CF Card
100x55x 18.5 mm)

Figure 2: View of a subject wearing the portable instrument by using a back supporter.

Young Elderly

mH^j^f^^

1 2 3 4 5 6 7 8 9 1 0

1 2 3 4 5 6 7 8 9 1 0

3 4 5 6 7 1 2 3 4 5 6 7 8 9 1 0
[
Time sec ]
Figure 3: Typical examples of accelerations as measured in healthy young subject and an elderly
before the intervention.

Firstly, we investigated the dynamic stability in comparison with the young and the elderly sub-
jects. Secondly, we demonstrated efficacy and effectiveness of the intervention for elderly, quanti-
fying degree of improvements on the walking stability. The intervention program was designed for
elderly living in the community through the continuous five-month training conducted by medical
doctors and physical therapists. The training program was intended to improve aerobic and phys-
ical performance by strengthening the muscular group involved in standing and walking. Subjects
attended two-hour classes once a week.

RESULT

Figure 3 shows typical examples of acceleration waveforms as measured in healthy young subject
(left) and an elderly subject before the intervention (right). The elderly presented clear fluctuations
on the waveforms, resulted in large value of the Lyapunov exponents. Figure 4 illustrates average
values of the estimated Lyapunov exponents comparing with the young and the elderly in the
direction of lateral, vertical, and anteroposterior respectively. The lower and upperlines of the