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A new flexible contact structure using the principle of air pressure amplification is proposed to enable better access to information for the blind. First, the structure and working principle of piezoelectric flexible Braille contacts were designed and analyzed, and the theoretical model of air pressure amplification and theoretical expressions were established. Then the gas–solid coupling simulation analysis was carried out using COMSOL Multiphysics software to derive the influencing factors of the system flexible contact amplification and the degree of influence of different gases on the contact output displacement, and the structure of flexible Braille contacts was tested experimentally. The experimental results show that when the diameter of the air cavity is 24 mm, the height of the cavity is 6 mm, the thickness of the flexible film is 0.1 mm, the contact height is 2 mm, the input voltage is 135 V, the resonance frequency reaches 196.5 Hz, the maximum output displacement of the piezoelectric flexible Braille contact is 0.286 mm, and the point display effect of the Braille contact is more significant, which verifies the feasibility of the device. [ABSTRACT FROM AUTHOR]

Due to insufficient muscle strength, a novel rehabilitation mechanism of the shoulder joint exoskeleton is proposed and analyzed based on gear and rack transmission, which solves the problem that stroke patients need repetitive exercise rehabilitation training. First, the range of motion angle of the shoulder joint is determined, and the mechanical structure of shoulder joint rehabilitation is designed. The arc rack is engaged with the output shaft gear of the reducer, and the servo motor is utilized as the driving force to realize the internal/external rotation movement of the shoulder joint. The motor connects the horizontal connecting rod and the rotating rod through the cross roller bearing to realize the abduction/adduction and flexion/extension movement of the shoulder joint. Second, the kinematics and dynamics of the shoulder joint exoskeleton are analyzed, investigated, and verified for the rehabilitation mechanism. The simulation analysis of the mechanism is completed in the virtual prototype. The changes in the joint angle and end trajectory and joint moment with time and angular velocity under the given working conditions are obtained, which directly reflect the movement of each joint of the rehabilitation mechanism. Finally, aiming at the nonlinear disturbance in the trajectory tracking control of the rehabilitation mechanism of the shoulder joint exoskeleton, the trajectory tracking approach of the mechanism is achieved aided with the closed-loop PD iterative learning control method. The results demonstrate that the actual trajectories are in good agreement with the desired trajectories, which can achieve effective tracking and improve the control quality of the system. [ABSTRACT FROM AUTHOR]