Ankle flexible exoskeleton based on force feedback admittance control
In response to the need for ankle rehabilitation training,a lightweight,easy-to-wear flexible ankle exoskeleton robot was designed using modular drive units and Bowden cables through analysis of ankle joint mechanics.The robot can provide assistance for ankle plantarflexion/dorsiflexion and inversion/eversion movements.Position control and torque control are used for flexible exoskeleton during the dorsiflexion and plantarflexion stages,respectively.Position control is mainly based on traditional proportional integral derivative(PID),while torque control uses force as a feedback signal to establish an admittance model between the interaction force difference and the Bowden cable core displacement compensation.The admittance parameters are dynamically adjusted through the Sigmoid deformation function to meet the requirements of assistive torque output and human-machine interaction compliance.Experimental data showed that the position tracking error was stable within 0.46 cm,and the force output error was stable within-1.5-1.5 N,meeting the needs of human rehabilitation training.
ankle jointrehabilitation trainingflexible exoskeletonforce feedbackadmittance control
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