Design And Research Of A Pedal Knee And Ankle Joint Rehabilitation Device

As China gradually steps into an aging society,the proportion of joint injury and tissue function degradation caused by age,disease and other factors is also increasing.The knee and ankle joints of lower limbs have a high incidence of joint injuries due to their heavy load bearing and large amount of daily activities.In the aspect of joint injury rehabilitation,the modern rehabilitation concept tends to the rehabilitation method of specific repetitive movements.The commonly used artificial rehabilitation methods of knee and ankle joints do not meet the needs of current use,while most knee and ankle rehabilitation devices have relatively single functions.According to the current rehabilitation needs and the research status of rehabilitation devices,a pedal type knee and ankle rehabilitation device were designed.The specific work includes the following aspects.Firstly,the structural aspects of the knee and ankle joints of the lower limbs were analyzed.The structural characteristics and movement patterns of the knee and ankle joints were obtained.As to design a pedal knee and ankle rehabilitation device based on cycling mode.The structure includes five parts: drive structure,two-way pedal structure,track structure,frame and shell,which could be rehabilitated by knee flexion and extension of one degree of freedom,and two degrees of freedom of ankle varus/valgus,plantar flexion/dorsal extension.The pedal was connected with the track structure.The main motor drived the pedal to cycle or drived the track to rotate,which could drive the pedal to turn inward and outward to achieve ankle inward and outward training.The small motor drived the pedal to turn forward and backward to achieve ankle plantar flexion and back extension training.In the process of riding,knee flexion and extension training could be achieved.The designed rehabilitation device had three passive rehabilitation modes: knee and ankle rehabilitation mode of passive riding with one or two legs,ankle plantar flexion and dorsal extension rehabilitation mode,ankle varus and valgus rehabilitation mode,and two active rehabilitation modes of active riding and free pedal mode.According to the human quality data and the driving needs of different rehabilitation modes,the drive selection of rehabilitation devices was carried out,and the safety design of rehabilitation devices was carried out at the same time.Secondly,the feasibility of the designed rehabilitation device was analyzed,and the kinematics of the rehabilitation device was simulated by using Adams simulation software.The training angles of the inside and outside rotation and the front and back rotation of the pedal of the rehabilitation device can reach 37°/25° and45°/30°,respectively,which could realize the training of ankle varus 37° and valgus 25 °,and the training of plantar flexion 45° and dorsal extension 30°.By adding a human lower limb model and using kinematics simulation,the rehabilitation angles of the rehabilitation device for knee flexion and extension,ankle plantar flexion/dorsal extension,and varus/valgus were 61°/101°,15°/16°,37°/25° in the knee and ankle rehabilitation mode.By studying the angular velocity of ankle joint rotation with two degrees of freedom during rehabilitation training,it was concluded that the rehabilitation device was safe when the rotational speed is less than 25r/min.Then the dynamic simulation of the rehabilitation device with a lower limb model was carried out,and the maximum driving torque of the central axis was 16.2N·m and 20.2N·m,respectively during the rehabilitation training of the knee and ankle joints of one leg or two legs,and the maximum driving torque of the central axis during the rehabilitation training of the ankle plantar flexion and dorsal extension was 6.8N·m,all the maximum driving torque were less than the designed value of the driving torque of the rehabilitation device,which verified that the driving design of the rehabilitation device could meet the operation needs under different rehabilitation modes.To obtain the stress condition of parts during the simulation process.Thirdly,the stress analysis of the pedal frame and track structure of the rehabilitation device was carried out by using the ANSYS Workbench software,which verified that its strength can meet the using needs of the rehabilitation device.Then the influence of the deformation of the telescopic shaft on the gear and rack fit,and the influence of the deformation of the track mechanism on the inversion training angle of the rehabilitation device were studied.Through the deformation simulation of the telescopic shaft and track structure,which was analyzed that the deformation of the telescopic shaft would not affect the gear and rack fit.The influence of the track structure deformation on the inversion angle and the inversion angle was increased by1° and 0.8° respectively.Finally,the corresponding muscles of the knee and ankle joints of the human lower limbs were analyzed.The inverse kinematics analysis of the human body during walking was carried out by using Opensim software,and the changes of the length of the muscle-tendon and muscle fiber during walking were analyzed.Through the experimental collection of motion data,the human inverse kinematics simulation of rehabilitation training was carried out,and the changes of the length of muscle-tendon and muscle fiber were observed.By comparing with the human walking,the rehabilitation training effect of the designed rehabilitation device on the knee and ankle joints was effectively verified.