Research On Control Of Asymmetric Lower Limb External Skeleton Based On Admittance Control

The lower extremity exoskeleton is a wearable,people-oriented,mechatronics mechanical device for auxiliary,not only have the protection of human body structure and support functions,but also enhance the body's strength,speed and endurance,has been widely used in individual combat,carrying heavy loads and help the disabled.With the rapid and healthy development of the national economy and the improvement of people's life,above knee amputee eager to engage in the stairs and mountaineering activities such as in the case of weight,amputee soldiers also eager to be able to continue loading the long-distance March and rescue mission.But in the current research,exoskeleton robots are only for the two legs of the living crowd,there is no available for patients with knee upper limb wearing exoskeleton robot.For patients with lower limb amputation daily walking and walking function demand,this paper will study the exoskeleton robot and intelligent lower limb prosthesis combination is proposed for knee amputee asymmetric exoskeleton robot.Compared with the exoskeleton robot for able-bodied people,the asymmetric lower limb exoskeleton robot needs higher sensitivity and safety to realize the coordinated control with the disabled.In view of the practical application requirements of the asymmetric exoskeleton robot,this paper proposes a control method based on admittance control to control the joint of the lower limb and the lower limb.The main contents include:(1)Data acquisition of human lower limb joint motion.The human gait is divided into single foot support phase and double support phase(including two feet to support one feet virtual touch ground).Based on the seven-bar model,the kinematics and dynamics modeling of the lower limb of the human body was carried out,and the torque curve of each joint of the lower limb in the gait cycle was obtained,and the rationality of the dynamic model was verified.(2)Kinematics and dynamics modeling of lower limb exoskeleton robot.Based on the design of asymmetric exoskeleton robot mechanism,based on the first category of the Lagrange equation and the idea of segmentation modeling,establish the lower extremity exoskeleton swing phase and the support phase of the kinematics and dynamics model.(3)Modeling of admittance control system of lower limb exoskeleton robot.On the basis of elaborating the principle of admittance impedance,the admittance model of the articular drive mechanism of the lower extremity exoskeleton robot is established,and the impedance characteristic of the external leg of the lower limb is analyzed.Based on the analysis of the virtual inertia compensation of man-machine coupling system,the closed-loop admittance control system model of lower extremity exoskeleton robot was established.(4)Control simulation and performance evaluation of lower limb exoskeleton robot.Because of the different dynamic models of the support and swing phases of the lower limb exoskeleton robot,the admittance control method and the calculating torque plus admittance control method are adopted respectively for the support and swing phases of the lower limb exoskeleton robot.The admittance control method of the oscillating phase was simulated by the second chapter of the human body lower limb joint motion data.Based on the simulation results,the performance evaluation of the lower extremity exoskeleton admittance control method was carried out from the aspects of followability and interference.