Dynamic Analysis Of Human-machine System And Research Of Assistance Ability Of Lower Limb Exoskeleton Robot

Exoskeleton is a mechanical and electrical system combining mechanical structure and intelligent sensing.In the military field,exoskeleton can enhance the load-bearing ability and durability of soldiers.In the medical field,exoskeleton can provide rehabilitation training for patients with hemiplegia and stroke,help people with lower extremity disability or cerebral palsy to gain freedom of walking,and assist the elderly and the weak to carry out daily activities.The rigid mechanical structure of the power assisted exoskeleton makes it able to bear a large load,but the human joints are very flexible,and its movement is complex and diverse.In the process of walking,the human body and the exoskeleton are a whole.If the movement of the exoskeleton affects the human movement or its power assisted improperly,the movement of the human machine system is unbalanced,which may cause damage to the human body.Therefore,this thesis mainly focuses on the research of exoskeleton assistance,human-machine system dynamics and human-machine dynamic stability.The main contents are as follows:(1)The kinematics and dynamics of human walking are studied.Through the human walking experiment,the plantar pressure and lower limb joint motion data are recorded.Through the establishment of a simplified mechanism model of the human body,the human body kinematics and dynamics model are established.On this basis,the force law of human leg in gait is analyzed,and the need and timing of assistance in walking are analyzed.(2)In this thesis,the dynamics of a man machine composite system composed of human exoskeleton is analyzed.According to the dynamic model of human walking and the analysis of the need of assistance,a walking robot with lower limb exoskeleton is designed.According to the structural characteristics of human and exoskeleton,the physical model of the parallel mechanism of human-machine composite system is established,and the dynamic model is established by Kane method.In addition,ADAMS software is used to simulate the motion of the human-machine system,and MATLAB software is used to simulate the dynamic model.(3)According to the established dynamic model of man machine parallel connection,the dynamic calculation of power assisted process is carried out.The results show that wearing the exoskeleton can reduce the output of the thigh muscle force,and has a significant effect of assistance.It can obviously reduce the internal force of the knee joint,and has a significant load reduction protection effect on the human knee joint.(4)The stability of lower extremity exoskeleton walking was analyzed.Through human-machine walking experiments,the plantar pressure of the human body was measured in the case of exoskeleton assisted walking.Based on the improved ZMP dynamic stability criterion,the human-machine walking stability of the exoskeleton with different assistance levels and different users were analyzed,and it was proved that it can meet the stability requirements of people wearing their walking.