The use of a heel-mounted accelerometer as an adjunct measure of slip distance.

A human-centered measure of floor slipperiness could be useful as an adjunct to conventional tribologic measures. This paper reports on the development and evaluation of a measure of slip distance based on variables derived from the signal of a heel-mounted accelerometer. Twenty-one participants walked on a laboratory runway under several surface slipperiness conditions at three walking speeds during a protocol designed to produce a wide range of slip distances at heel strike. Analysis of variance showed significant effects of slip distance (no-slip, micro-slip and slide), walking speed (1.52, 1.78 and 2.13 m/s) and their interactions on peak forward acceleration, peak vertical acceleration and deceleration time of the heel following heel strike in 704 trials. Regression analysis of slip distance and deceleration time showed the strongest relationship with R2=0.511. Large individual variation in the strength of this relationship was observed. The heel-mounted accelerometer may have utility as an adjunct measure in the evaluation of floor slipperiness, particularly for field applications where direct measurement may not be feasible.