Research On An Exoskeleton Robot For Rehabilitation Of Thumb Function

In the clinical practice,the number of patients with finger tendon injury accounted for half of the numbers with hand trauma.In the healing process,there would be tendon adhesion phenomenon.To reduce the degree of tendon adhesion to help restore finger motor function,the patient need to do early passive rehabilitation training.Thumb is the key of the human hand to achieve grasping function.If a man loses the thumb,the function of his hand will disapear nearly 40%.This paper aimed to design a thumb function rehabilitation robot to replace the physiotherapist to complete high-intensity rehabilitation training.Firstly,the joint structure and movement characteristics of the thumb were analyzed,and a 3DOF robot was adopted to realize the opposition movement function of the thumb.The f/e movement of the IP and the MP joint is achieved by means of the back exoskeleton structure of the planar guide-bar mechanism,which ensures that only perpendicular reaction forces are applied on the phalanges.Using the Bowden cable achieveed long-distance power transmission.The kinematics and statics model of the robot was set up for the robot's motion control.Secondly,to make the robot has the ability of detecting feedback,a non-contact sensor based on hall effect was designed to detect the thumb joint angle.A elastic torque sensor based on bowden cable was proposed.The exoskeleton joint driving moment could be caculated through the joint angle sensor and motor encoder information.Because of backlash hysteresis,the mathematical model of torque sensor was modified to improve the accuracy of the measurement.The calibration experimental platform was set up,and the static calibration of the sensor was completed.Thirdly,the overall design diagram of the robot control system was set up.The design of the underlying hardware of the robot system was completed,including the sensor signal acquisition module,motor driving module,bluetooth communication module and power supply system.A programmable chip based on Nios II soft core was adopted to implement real-time control of robot movements.The interactive software is designed and perfected,which made the movement range and speed of robot rehabilitation training be adjusted in real time.Finally,the experimental study of the thumb rehabilitation robot was carried out.The mechanical structure,sensors and control system of the robot were verified respectively.On this basis,the normal rehabilitation training experiments were conducted.The experimental results show that the designed robot can reliably assist the thumb rehabilitation training.