Performance Comprehensive Evaluation Index Of Gait Instability Theory

Gait instability, including slips and falls, are the frequently accidents in our dailylife. And these accidents make more hurt because of losing balance of human body.The light bring about tissue hurt, for instance, ankle sprain, ligament of knee sprain.The heavy probably makes the death happen. In order to avoid this hurt happened inour environments, so we must study out this problem for finding out the key point ofhuman slipping and falling. This dissertation presents human gait instability theoryand evaluation system to build the gait instability. The following contributions havebeen made.Starting from the basic movement characteristics on foot, with comprehensiveconsideration of usual activity of each joint of human lower limb, the seven-degree offreedom and seven-body-segment gait model of human lower limb was built and thekinematic and dynamic parameters of the model in the gait cycle were described. it ispossible that gait instability theory of performance evaluation index system would beanalyzed under the unified model definition. After introducing COM(center of mass)and BOS(base of support) mapping function model and constructing the basicmeasurement index to judge gait stability, then it make possible to quantitativelyanalyze gait stability.Based on the lower limb gait model and the introduction of musculoskeletalmodel, the gait model would be optimized again by considerations of muscle strengthof human joints. And the method describing gait behavior characteristics combinedwith nerve Electromyogram(EMG) was put forward. Constructing the gait model oflower limb based on nerve muscle mechanics, and the method that reverselycalculates the joint muscle force through the kinematics and dynamics parameters oflower limb was built. Through the experiments and the simulating calculation resultof the muscle force, behavior of neuromuscular mechanics and surfaceElectromyogram(sEMG) of the relative lower limb muscle group were systematically analyzed in the normal gait and instability gait. So it laid a theoretical foundation forgait instability process description and gait instability behavior evaluation framework.Based on autonomic balance reaction characteristics of gait instability behavior,kinematics and dynamics performance evaluation indexes of independent balance gaitparameters were established and these indicators were put into use in the whole studyprocess of gait instability and autonomic balance response. A kind of method thatcould study on autonomic balance gait based on neuromuscular mechanics theory wasput forward. With lower limb joints and muscles associated with neuromuscularperformance and on the basis of lower limb gait kinematics and dynamics parametersvariation characteristics, autonomic balance recovery behavior characteristics andstrategies have been carried on the elaboration by slips and falls gait experiments.A probability model forecasting slips and falls was put forward from themacroscopic angle to evaluate gait instability behavior. The related tests have beendone on this condition the different angle, different trails textures and differentsurface contamination, and the density distribution function was obtained about thegait instability, and the probability prediction model by optimum design of slips andfalls was established. On the basis of gait instability probability prediction model, theexperiment of specific level trails gait instability have been done with the reactiontime, movement time and the total time, and study the relationship betweenprobability of slips and falls and UCOF(Utilized coefficient of friction). Bydiscussing the relevance between the reaction time, movement time and the total timeand the instability prediction probability, the relevance between gait instability andrelevant performance indicators of exercise physiology and psychology recurring tothe foot-ground contact force variation characteristics.Based on the environment factors and human factors of gait instability, theexternal factors, internal factor and the relevance between them were discussed.Using the main cause analysis of multivariate statistical analysis, the gait instabilitythe cause factors of8indicators mentioned in this article were studied, in order to findthe key factors affecting the gait stability. The average power of the major muscles oflower limbs in the gait cycle, the response time of subjects of interference stimulate nerve impulse and speed of plantar heel of contact time, have played a key role in thewhole gait instability phenomenon. And these three cumulative variance contributionrates have reached the percentage of87.524%. Subsequent related gait instabilityprevention strategies and aid-devices design could determine the important directionto solve the problem around the related factors.The research of this dissertation has important theoretical significance andpractical value to enrich and develop the gait stability of related theory, to promotethe gait rehabilitation training strategy, to set down independent balance recoverystrategy, and to design and improve lower limb aid-devices.