Structural Design And Research Of A Flexible Parallel Robot For Upper Limb Rehabilitation Based On Cable-driven

Over the years,our society is faced with an increasingly serious problem of aging population,The high medical cost brings heavy burden to the patient’s family and the society.The incidence of neurological diseases,mainly stroke,the sequelae caused by stroke,in particular,the movement of the upper limbs is impaired,still bring great pain to the patient’s heart and spirit.Expensive rehabilitation treatment costs also increase the burden on the patient’s family.With the rapid development of computer technology and robotics,upper limb exoskeleton rehabilitation robot has become a research hotspot in the field of rehabilitation medicine.Restricted by traditional motion pairs and rigid structures,it is difficult to ensure the consistent motion form between the upper limb exoskeleton robot and the complex joints of the human upper limb.This paper developed an upper limb exoskeleton robot,and conduct a more in-depth study and experiment.Considering the advantages of flexible parallel mechanism such as light weight and good flexibility,a 6-dof cable-driven upper limb rehabilitation flexible parallel robot is presented and designed.The main tasks and responsibilities are as follows:Firstly,based on the anatomy and kinematics of the upper extremity of the human body,the composition of structural characteristics and movement forms of each joint of the upper extremity of the human body is analyzed.Based on the three-dimensional motion capture system,acquire all motion angle of each joint of the upper limb,and the structure design of the robot is completed.The shoulder-elbow joint mechanism is provided with a gravity compensation device and a passive adjustment device,which solves the problem that the shoulder joint overcomes the gravity to do a large work load and the glenohumeral joint center does not match the robot during movement.The wrist joint introduces ropes to drive the flexible parallel mechanism,the moving platform simulates the end of the metacarpal bone,the fixed platform simulates the end of the radius and ulna,and three cables simulate the muscles to drive the parallel mechanism,which effectively solves the problem of dislocation between the rehabilitation mechanism and the human wrist.Secondly,on the basis of the mechanical structure of the upper limb rehabilitation robot,set up the D-H parameter model,analyse the forward and inverse kinematics of the shoulder and elbow position of the robot.The kinematic space of the mechanism was solved with Monte Carlo method.The dynamic characteristics of shoulder-elbow mechanism were analyzed by Lagrange method.Through simulation analysis,it is obtained that the torque and angular acceleration curves of each joint,they are continuous and glossy,which verified the rationality of the designed upper limb rehabilitation robot shoulder-elbow mechanism.Thirdly,aiming at the axial displacement and flexibility of the spring in the wrist flexible parallel mechanism,based on the finite rotation tensor method and the force and moment balance analysis method,the mathematical model of the inverse kinematics of the system is constructed.Through the analysis of the mechanism model,the numerical solution of the length and tension of each cable at 0～75° is completed.Aiming at the problem of flexible vibration,the dynamic of flexible parallel mechanism is solved based on Lagrange method.Through the simulation analysis,the physiological motion space of the human wrist and the effective working space of the mechanism are obtained,which verifies wrist mechanism meets rehabilitation training requirements.Finally,the structure prototype and control system of the upper limb rehabilitation flexible parallel robot are developed based on the cable-driven design.A sliding mode variable structure controller for upper limb rehabilitation robot based on RBF neural network is proposed to solve the problem that the robot is disturbed by the lack of consciousness of autonomous motion of the patients in the period of paralysis and spasticity,the trajectory tracking performance of the upper limb rehabilitation robot system is enhanced.The upper computer software of the robot system is developed based on C language.The passive training mode and teaching training mode of the upper limb rehabilitation robot are tested.The results shows that the upper limb rehabilitation robot meets the design requirements,and provides a reference for the design of such robots.