Kinematics Performance Analysis And Optimization Of 2-UPS-RR Parallel Hip Rehabilitation Mechanism

Hip joint is one of the important weight-bearing joints of the human body,which is easily damaged.Wearable hip rehabilitation mechanisms can assist patients with motion rehabilitation,and the research on its structure and performance has become one of the hotspots in the field of medical and engineering integration.In order to help patients with impaired hip joint recover early and realize free walking,an adjustable hip rehabilitation mechanism with 2-UPS/RR configuration is presented.The mechanism has two rotation degrees of freedom and one translation degree of freedom,which can drive the affected hip joint to achieve flexion/extension,adduction/abduction and traction movements.The adjustment function of the mechanism ensures the consistency of the centers of human and the mechanism rotation,which provides greater security for rehabilitation process.Firstly,based on human anatomy and rehabilitation medicine,the configuration characteristics and movement modes of human hip joint are analyzed.There are two main movement forms of human hip joint: rotation and translation.Therefore,the parallel mechanism with 2-UPS-RR configuration is adopted as the choice of hip joint rehabilitation mechanism.Combined with mechanical mechanics,ergonomics and biomechanics,the design of the adjustable center and the optimization of the shape of the mechanism make it comfortable to wear and accurate to adjust the center.In addition,the driving mode and object of the mechanism are analyzed.The mechanism materials are selected.Secondly,the degree of freedom of the 2-UPS-RR parallel mechanism is analyzed using screw theory.The position inverse solution of the mechanism is solved using position vector method,and its velocity Jacobian matrix is solved by inverse solution equation.The 3D dynamic method is used to obtain the coordinate values of the center point of the moving platform of the mechanism,and then the three-dimensional workspace of the mechanism is obtained.Thirdly,a prototype model of the mechanism is established in the mechanism dynamics simulation software Adams,the inverse kinematics of the hip joint is simulated,and the correctness of the inverse solution is verified according to the coordinate variation law of the output trajectory.Three kinds of rehabilitation training modes are simulated to obtain the variations of the velocity and angular velocity of the moving platform.The results show that the rehabilitation mechanism can realize the flexion/extension,adduction/abduction and traction movements of the hip joint.Several kinds of trajectory planning methods are analyzed and compared,of which the T-type trajectory planning is adopted to optimize the dynamic performance of the 2-UPS-RR rehabilitation mechanism.The curves obtained by simulation are continuous and smooth,which proves that the rehabilitation process is safe and reliable.Finally,the mechanism is remodeled using human mechanics simulation software Anybody,combined with the human standing model,a human body simulation system is established.The maximum muscle activity of human body and the stability of rehabilitation process are taken as the important factors,the feature of the curves are analyzed and compared to verify the safety of the rehabilitation process to human muscles.The training and rehabilitation assessment programs for patients at different stages are put forward,which has positive significance for patients' early recovery.