Stepping behaviors based on tribological and dynamical investigations

In order to better understand the tribological mechanism of slipping and falling while walking, stepping behaviors on a level way or a ramp were studied. Forty volunteers aging from 8 to 69 participated in the study and were divided into four groups according to their age. The contacting force between foot and ground was detected by a force plate embedded in a walk way. According to the detection force, required coefficient of friction (RCOF) was calculated. Influence of ramp angle and age on RCOF was also studied. Results have shown that the contacting force and RCOF distribute regularly and the stepping process can be divided into landing stage and taking off stage which can be characterized as two peak values of forces. The landing stage is a braking process while taking off stage is a starting process. The RCOF reaches the peak values just at the moment of fully landing and the separation of foot from the walking surface. It was found that the dynamic and tribological behaviors of stepping were affected not only by the stepping conditions (uphill, level and downhill) but also by the angle of ramps and the age of subjects.