Research On The Relationship Between Flexion Characteristics And Fall Modes In Human

With the advent of an aging society,the health problems of the elderly have received more and more attention.Due to the continuous decline of the physical function,it is easy for the elderly to fall,so falling has become one of the important reasons for injury and even death of the elderly.Falls cause serious physical and psychological injuries to the elderly,and impose heavy burdens on society and families.The problem of falls among the elderly is widely concerned by institutions and scholars at home and abroad.In this paper,the elderly fall was taken as the research object.The combination of human fall simulation and human fall experiment was adopted.The changes of joint flexion and extension under forward fall and backward fall modes were explored.Through stability analysis,safe human postures were determined,and a fall prevention support device was conceived.Based on the research status at home and abroad,thousands of elderly fall cases in a certain area were studied.By analyzing the fall environment,fall mode,injury nature and injury site,the fall mechanism of the elderly was determined: it is difficult for the elderly to use their hands and arms to take effective fall protection measures when falling.Based on the fall mechanism,the three rigid body fall dynamic model and dynamic equation were established.By referring to the literature on the elderly’s human inertia parameters and joint torque,the parameters of the equation were determined.The Euler method was used for numerical solution,and the constraint range of each joint of the human body and the calculation method of collision impulse when falling down were determined.Through MATLAB software,the fall process of the elderly under different initial postures was simulated.When falling forward,the knee joint flexes,the hip joint extends,and the fall hits the ground at the knee.When the torso leans forward more than a certain angle,it may become a head collision.When falling backward,the knee joint and hip joint buckle,and the collision part with the ground is the hip.According to the simulation results,three initial postures of falling forward and three initial postures of falling backward were adopted.The fall experiment environment and system based on Open Pose human posture estimation were built,and the fall experiment scheme was designed.Because of the danger of the fall experiment,young subjects were allowed to fall in the way of the elderly.Through the joint angle data of the fall experiment,the changes of the flexion and extension of the joint and the risk of falls in the six initial postures mentioned above were analyzed.The characteristics of the changes of the knee and hip joint angles when falling were summarized,and the simulation results were verified.The ankle,knee and hip joints were regarded as torsion springs,and the undamped free vibration differential equations were established.Through eigenvalue analysis,the safe postures of human body without falling were determined,and the eigenvalue and natural vibration mode of three initial posture models of forward falling and three backward falling were analyzed.A fall prevention support device was conceived,the required stiffness of each torsion spring was determined,and the eigenvalue and natural vibration mode of the model under the support device were analyzed.The influence of each joint on stability was explored.The hip joint only needs a small torque to keep the human body stable,while the ankle joint needs a larger torque.