| With the development of mechatronics and computer technology,more and more scholars have turned their attention to the field of medical rehabilitation.In China,the incidence of stroke patients is high,and the age of onset is getting lower and lower.Most patients have hemiplegia and difficulty in movement after emergency treatment.The best way of rehabilitation is to complete the long-term training task with the help of the nurse.Due to the lack of rehabilitation nursing resources,many patients have to choose home rest and miss the best recovery period.Similarly,many elderly people suffer from osteoarthritis of the knee.The joints are swollen,painful,and restricted in movement.They also have severe movement disorders,especially sit-to-stand(STS)transfer.Currently,knee orthosis is widely used to reduce the pain in movement.According to the actual needs of these two types of patients,this article designs a multifunctional wheelchair for lower limb rehabilitation training,which is used to support the gravity of the human body in a STS transfer,and at the same time can help the patient to perform muscle training and restore muscle strength.Firstly,the healthy young people are taken as the research object,and the motion data in the process of sitting and standing conversion are collected by Vicon motion capture system,and the joint angle and joint moment are calculated by opensim.Through the analysis of the calculation results,the weight reduction support as the core to reduce the burden of the lower limbs,the pelvis as the object of wheelchair,the ischian tubercle as the main force point,using the arc to fit the ischian tubercle trajectory,as the design standard of the wheelchair end actuator.Based on the trajectory of human body and hemiplegia rehabilitation method,the design of multifunctional wheelchair is completed.In terms of structural design,multifunctional wheelchair provides three functions: leg lifting,back leaning and sitting and standing conversion.The wheelchair structure is used as the frame to facilitate the movement of patients.The auxiliary standing structure adopts the electric push rod and parallel link as the actuator to restore the fitting arc track,while the end actuator is always horizontal to ensure the body balance.In the aspect of control,PC is used to establish human-computer interface,PC communicates with driver through usbcan module,and controls the speed and current(torque)of motor,so as to realize two modes of passive training and semi-active training,which are used in different periods of rehabilitation.The three-dimensional structure model is introduced into the skeletal muscle model to form the coupling model,and the movement of the electric push rod and the humanwheelchair interaction force are taken as the simulation input to carry out the inverse kinematics coupling simulation analysis.The results show that the wheelchair assisted mode has good comfort,and the joint torque is significantly reduced in the coupling simulation,which can reduce the burden of the lower limb joint in the process of sitting to standing,and verify the rationality of the structural design.Finally,according to the design and manufacture of the physical prototype,the performance of the prototype is analyzed through the experiment of auxiliary sit and stand conversion.In the experiment,the multi-functional wheelchair can help the subjects to complete the movement smoothly from sitting to standing,and the plantar pressure is significantly reduced.Through the biomechanical analysis of opensim,the results show that the joint torque and muscle force in the assisted standing experiment are significantly reduced compared with the human body’s active completion of sitting and standing conversion,which reduces the burden on the lower limb joints and muscles of the patients.Therefore,it can be concluded that wheelchair assisted stand design plays an auxiliary role in sit and stand conversion,and further clinical research can be done. |
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