Research On Control Of 2-DOF Ankle Rehabilitation Device

Ankle joint is extremely important joint of the human lower limbs and the injuries of ankle are quite common,which bring much limitation and inconvenience in people's lives.In the case of shortage of human resources in rehabilitation medical care,how to effectively assist patients in rehabilitation training of ankle is the focus of rehabilitation.As a hot way to solve this problem,providing patients with more effective rehabilitation for ankle joints flexibility and muscle strength recovery by using rehabilitation robots instead of therapist is becoming more and more popular.Then,on the basis of analysis and summaries of the characteristics and defects of the related fields,this paper studies the control system for an ankle rehabilitation device with new structure design,and establishes its overall control program.In this paper we put forward effective training modes in different stages of rehabilitation combined with anatomy and rehabilitation medicine.The rehabilitation training modes include continuous passive mode,traction mode,constant resistance mode,elasticity mode,assistant mode and compliant mode.The servo control schemes for different rehabilitation training modes are designed according to the functional requirements of each mode.According to the structure scheme for the ankle joint rehabilitation device,the kinetic model and kinematics model of the system were established with the consideration of the impact of feet on the device and complete the check on motor drive capability.On the basis of this,finish the control system modeling and simulation analysis of the rehabilitation device for different modes.For passive training mode,PD position closed-loop control model were designed.Trajectories are planned for continuous passive model and a traction mode.For the active resistance training mode which includes constant resistance mode and elasticity mode,a PI controller was designed for the current closed loop control.For semi-active training mode,a controller switching algorithm based on identification of the patient's active exercise intention by motor were proposed.For compliant mode,a double loop controller is designed which the outer loop is position loop and the inner loop is force loop.Modeling,simulation and analysis of all control schemes have been completed.The simulation results verify the effectiveness of the control schemes.According to the functional requirements of the control system,hardware design of the servo motor drive based on ARM microcontroller was completed.The overall system control workflow logic was set up.The generation of the underlying program and embedded procedures of control program were finished.Using dSPACE platform system to establish the experimental environment,we select the experimental subjects to complete the human-machine experiments,which include passive mode experiment,active resistance mode experiment,semi-active mode experiment and compliant mode experiment.The experiments achieve the function of different modes and the results are similar to the simulation which verifies the validity of the control schemes.