The Analysis Of Biomechanics For Closed And Open Kinematic Chain Motions

Human action is achieved by the contraction and relaxation of muscles which affect the link connected by the joints, muscles, and bones which are under the control and coordination of the nervous system, and doing link chain activities according to the will of people. The number of joints and the form of activities are different due to different people`s postures and actions. What`s more, human motor system is characterized with integrity and independence.Therefore, this started from the integrity of the human motion chain, use the 3D mtion capture analysis system and BTS FREEEMG 300 system,aiming at studying the rules and features of the human motion chain when the joints are linked to act by make comprehensive analysis of the kinematics and electromyographic. On one hand, the research can improve the human motion of kinematic chain theory and research methods further, on the other hand, it can also provide guidance to the design for sports training and rehabilitation training, and to the understanding the mechanism of sportThe body of the thesis include:(1)Closed kinematic chain—Experimental researches of legs Landing bufferIn this study,8 subjects participants took part in the experiment voluntarily,and three gravity center positions of human body of legs Landing buffer at the same elevation.In the process, measurement of joint movements and 16 muscles sEMG of lower extremity of subjects.And analyzed data statistically,exploring at the influence of gravity center positions and limb laterality factor on human of colsed linked chain biomechanical parameters.It turns out:1) The different position of the center of gravity of the human body will affect muscle activation.If center of gravity fall in the chain axis(Normal landing),it would be extensor of intermediate connection point for control movement.In case center of gravity rained on the front of chain axis(Forward landing), it would be extensor of distal link connection point for control movement.In the event of center of gravity rained on the behind of chain axis(Backward landing),additional pressure act on the proximal link,it would be extensor of proximal link connection point for control movement;2) Dominance and non-dominant link have asymmetry characteristic during knee flexion,distal flexor root meam square(RMS) non-dominant link than dominance link side significantly high.This discovery may help explain the ankle easily get hurt of superior leg than non-dominant leg when landing buffer.3)The core area muscles first activation in action of closed kinematic chain,This discovery may be become strong evidence of the core area is human movement “send a force source”.4) Ankle and hip principal reflect the flexibility, However, knee principal reflect the stability.Embodied in three stages: stability and flexibility on alternative distribution.(2) Open kinematic chain—Experimental research on forehand stroke in tennisIn this study, high-level 6 subjects tennis player participants took part in the experiment voluntarily,and actions of place the forehand swing and forehand stroke with sargent jump.In the process, measurement of forehand extremity movement and 18 muscles EMG of subjects.And analyzed the data statistically, explore at the influence of different links and Jump factor on human of open kinematic chain biomechanical parameters.It turns out:1) When the body output at the end of the open kinematic chain,speed will faster as the number of links increase,and from first part to end part the speed increase successively.When the rate of a component increase,the rate of former part near it will decline.2)The stability is often taken as the main part in action of open kinematic chain.The core area muscles first activation in action of closed kinematic chain is same to the closed kinematic chain when human do the action of open kinematic chain.