Local Dynamic Stability Assessment of Motion Impaired Elderly Using Electronic Textile Pants

Abstract

A clear association has been demonstrated between gait stability and falls in the elderly. Integration of wearable computing and human dynamic stability measures into home automation systems may help differentiate fall-prone individuals in a residential environment. The objective of the current study was to evaluate the capability of a pair of electronic textile (e-textile) pants system to assess local dynamic stability and to differentiate motion-impaired elderly from their healthy counterparts. A pair of e-textile pants comprised of numerous e-TAGs at locations corresponding to lower extremity joints was developed to collect acceleration, angular velocity and piezoelectric data. Four motion-impaired elderly together with nine healthy individuals (both young and old) participated in treadmill walking with a motion capture system simultaneously collecting kinematic data. Local dynamic stability, characterized by maximum Lyapunov exponent, was computed based on vertical acceleration and angular velocity at lower extremity joints for the measurements from both e-textile and motion capture systems. Results indicated that the motion-impaired elderly had significantly higher maximum Lyapunov exponents (computed from vertical acceleration data) than healthy individuals at the right ankle and hip joints. In addition, maximum Lyapunov exponents assessed by the motion capture system were found to be significantly higher than those assessed by the e-textile system. Despite the difference between these measurement techniques, attaching accelerometers at the ankle and hip joints was shown to be an effective sensor configuration. It was concluded that the e-textile pants system, via dynamic stability assessment, has the potential to identify motion-impaired elderly.

Fig. 1

Illustration of e-textile pants. (Only pants were used in the current study.)

Fig. 2

Vertical acceleration based maxLE at speed condition 1 (100% of normal speed). * Indicates significant system effect. ◇ Indicates significant group effect.

Fig. 3

Angular velocity based maxLE at speed condition 1 (100% normal speed). * Indicate significant system effect.

Fig. 4

Vertical acceleration based maxLE at speed condition 2 (110% of normal speed). * Indicates significant system effect. ◇; Indicates significant group effect.

Fig. 5

Angular velocity based maxLE at speed condition 2 (110% of normal speed). * Indicates significant system effect.

Fig. 6

Vertical acceleration based maxLE at speed condition 3 (120% of normal speed). * Indicates significant system effect. ◇ Indicates significant group effect.

Fig. 7

Angular velocity based maxLE at speed condition 3 (120% of normal speed). * Indicates significant system effect.