Kinematics And Dynamics Modeling And Analysis Of Parallel Hip Joint Assisted Exoskeleton

Power-assisted exoskeleton is a subject with great research value and potential development in the field of robotics.With the development and breakthrough of robot technology,it has broad application prospects and development value in military operations,heavy working conditions,aerospace,earthquake and disaster relief,sports entertainment,rehabilitation treatment and other fields.Among them,the wearable hip-assisted exoskeleton is an important link in the whole-body exoskeleton.it has the important position of connecting the upper and lower limbs and transmitting motion and power as the central hub.Based on the current situation that most of the lower limb assisted exoskeletons are serial exoskeletons to assist 1-2 DOF for hip joint motion.Therefore,the 3-UPS parallel mechanism is used to study and design the hip joint assisted exoskeleton with the advantages of the parallel mechanism: high stiffness,strong anti-interference,low inertia and good dynamic response.The main research contents of this thesis are as follows.Based on the physiological structure characteristics of human hip joint,considering the wearing comfort,safety and effectiveness of assistance,using stereophotography technology to detect the position of human hip joint center.From the perspective of ergonomics and bionics,designing a power-assisted exoskeleton that forms a 3-UPS/S parallel mechanism with human leg after wearing,so that in the process of cooperative movement,not only the movement center of the mechanism is consistent with the human physiological hip joint.In addition,it will satisfy to assist the 3-DOF movements of hip flexion/extension,abduction/adduction,and internal/external rotation.In order to analysis kinematics of the parallel mechanism,the first-order influence coefficient matrix is derived based on the influence coefficient method of the Screw Theory to obtain the inverse Jacobian matrix.Meanwhile,differing the geometric constraint equations of the parallel mechanism are used to obtain the velocity relationship between diving joints and driven joints,as well as,relationship between the velocity of end-effector and driving joints which are forward Jacobian matrix of the parallel powerassisted mechanism.Meanwhile,the correctness of the forward kinematic analysis is verified by using co-simulation based on MATLAB and ADAMS.The orientational and locational workspaces of the parallel mechanism are solved with the help of the inverse posture solution model and the finite discrete search method,taking the constraints such as link length of branch,link interference and the range of motion of each kinematic sub into account.The influence of the constraints on the workspace is also explored,and the parameters of parallel mechanism and its workspace are determined.In the assisted workspace,the mechanism motion performance is analyzed with the help of manipulability.The dynamics equations of the hip-assisted mechanism were derived based on the Lagrange method,and the dynamics of the mechanism was analyzed by ADAMS software,and the correctness of the virtual prototype model was verified through the path planning analysis of the three independent hip joints motion.Combined with the actual assisted workspace,the maximum hip joint assisted motion is analyzed.The motion state of each kinematic pair and the maximum output torque of driving joint are achieved under different load circumstances.