Research On The Probability, Mechanism And Control Measures On Slips And Falls Of Human Body While Walking

Slips and falls are serious problems in many countries, which can hurt people in bodyand mind at different degrees. Ship, bus and plane are common vehicle for people. Onceslips and falls occurs in these moving devices, injury will be more severe to people.Therefore, study on probability mechanism and control measures of slip occurring onthese static and kinetic floors has great theoretic and actual meaning.Walking experiments on a level way were carried out by the analysis and testplatform for gait friction (ATPGF) developed by Henan University of Science andTechnology. Results showed that age, sex, step length and walking speed affected slipprobability of people. In the four test groups, slip possibility of children was the highestwhile that of young adults was the lowest. Lateral slip tendency of male was higher thanthat of female but slip tendency in front to rear direction of female is higher than that ofmale. Slip possibility increased with increasing of step length but decreased withincreasing of walking speed.Effects of material and surface topography of friction couple on slip possibility werestudied by ATPGF. Results showed that material and surface topography of frictioncouple affected the slip possibility of human. Of all the shoe sole samples with differentgroove pattern, integrate slip potential of human body corresponding to polygonal linegroove was the highest, longitudinal slip potential of human body corresponding to crossstriation was the highest, and lateral slip potential of human body corresponding tolongitudinal striation was the highest. In the three floor materials, slip potential ofhuman body corresponding to steel plate was the highest, while slip potential of humanbody corresponding to ceramic tile and granite was equivalent. Slip potential of humanbody was low if there were small and abundance hump on the surface of floor.Ramp walking experiments were conducted by ATPGF. Results showed that lateralslip tendency was not affected by ramp inclination but slip tendency in heading directionincreases with increasing of ramp inclination. In the four test groups, slip possibility ofchildren is highest, which is equivalent and smallest for young adults and middle-agedpeople. Slip possibility of young adults and middle-aged people are equivalence andsmallest.Walking experiments under sinusoidal wave condition were also conducted byATPGF. Results indicated that lateral slip tendency didn’t change with test conditions.Slip tendency in heading direction varied with increasing of locations, amplitude and frequency of sea wave and position of foot contacting with ground. Slip to rear at themoment of taking-off occurred easily if the amplitude and frequency of sinusoidal wavewas higher.Physical and mathematical models of centrobaric motion trajectory were establishedby analyzing and simplifying the feature of human body walking. Based on the model,mechanism of slips and falls was analyzed from the point of mechanical view. Theauthor considered that the basic reason of slip was imbalance of moments caused by allforces. Human body would overturn to the right side if lateral moment of left foot washigher, while overturn to the left side if lateral moment of right foot was high. Bodywould overturn to back if moments caused by forces in front to rear direction or verticalforce of landing foot(at the front of center of mass) were low, on the contrary, humanbody would overturn to front if moments caused by forces in front to rear direction orvertical force of taking-off foot(at the behind of center of mass) were low. According tothe mechanical principle, major factors, including physical features of body such asheight and weight and walking parameters such as walking speed and step length andground status such as level way and ramp, which affect the potential of slips and fallswere analyzed. Results indicated that the higher the body height, the lower the slippotential and the heavier the body weight, the higher the slip potential when the walkingparameters were constant. While when the physical features of body were constant, thelonger the step length, the higher the slip potential and the faster the walking speed, thelower the slip potential. Slip potential at the moment of landing phase and taking offphase were equivalent when walking on a level way. Slip potential of landing was lowerthan that of taking off when ascending on a ramp. While slip potential of landing washigher than that of taking off when descending on a ramp. According to the slip effectfactors, main control measures were put forward to prevent slips and falls. One measureis decreasing the minimum required coefficient of friction for safe walking by adjustingwalking posture. Another measure is increasing the maximum required coefficient offriction provided by ground via changing the features of contact interface between footand ground.