Research On Control Algorithm Of A Robotic Walker For Gait Rehabilitation

China has been into an aging society,which brings the problems of elderly healthcare and movement disorders caused by nerve damage.Traditionally,gait training is carried out manually,requiring three or more expert physiotherapists and there are problems with low efficiency,high labor costs,and inconsistent training effects.Compared with traditional gait training,robotic lower limb devices have the following advantages:1.The robotic devices can carry out high-intensity and repetitive training task.Consequently,the course of treatment,the efficiency and human resources would be shortened,improved and reduced respectively.2.It has higher accuracy than traditional gait training.3.The VR technology and multimedia technologies are easily installed in robotic devices,which would make training process more interesting.The rehabilitation equipment for lower limbs in the world most adopt exoskeleton structure in the mechanism.They focus on patient’s joint trajectory,but pay less attention to patient’s pelvis and they ignore the brain remodeling.In terms of control strategies and methods,most rehabilitation robot ignore the control of speed.Therefore,the development of rehabilitation robots that have intention recognition,focus on pelvic movement,and promote brain remodeling are of great significance to make up the shortage of rehabilitation robots and solve the problems brought by the aging population.Hence,as the key technology,the control of movement and body weight support system(BWSS)plays an important role in the development of rehabilitation robots.In this paper,the kinematics modeling of the mobile platform and the dynamics modeling of the BWSS are conducted based on a designed rehabilitation robot.The control algorithm for the mobile platform and the BWSS are designed,providing the reference for the rehabilitation robot control and the foundation for the clinal experiment of rehabilitation robot.The research work of this paper is as follows:1.In term of the rehabilitation demand of the patient,the mechanical structure and control structure of the rehabilitation robot are described.Based on the rehabilitation robot,the kinematics analysis of the mobile platform is conducted and the kinematics modeling of the mobile platform is conducted.Meanwhile,the kinematics and dynamics analysis of the BWSS are conducted and the Newton Euler recursion equation of the BWSS is established.The research work above provides the theoretical basis for the control algorithm of moving platform and BWSS.2.The control law is designed by the combine of PD controller and torque calculation method based on the dynamics model of BWSS.For the purpose of reducing the chattering of the friction part in the control law,a saturation function is designed.The motion model of the weight support system is constructed,based on what the proposed control method is simulated in Matlab/Simulink.3.According to the demand of patients for moving platform,an intention recognition algorithm based on pelvic force is proposed by the eigenvalues which is extracted through an experiment.Combined with PD control and fuzzy control,a fuzzy-D control method is designed to solve the problem of moving speed based on the kinematic model of moving platform.With the combination of intention recognition algorithm and fuzzy-D control method,the control algorithm of moving platform is proposed.4.For the purpose of verifying the performance of the proposed control method of mobile platform,a number of volunteers were recruited to carry out the experiment.The trajectory was fitted.Furthermore,the advantages of the proposed control method are analyzed by comparing with the traditional PID method.In order to verify the effectiveness of the proposed chassis movement control method,a simulated patient experiment is carried out,and the result proves that the proposed control method of mobile platform is effective and can be carried out in clinical trials.The research of mobile platform and BWSS of rehabilitation robot are carried out in this paper.The mobile platform control algorithm and BWSS control algorithm based intention recognition are designed on the basis of kinematic modeling and dynamic modeling.The effectiveness of the proposed method were verified by experiments and simulation.The research results can be used in the Man-machine interaction control of the rehabilitation robot,which is helpful to promote the research of the control of the rehabilitation robot.