Zero Calibration And Motion Control Of Cable-Driven Rehabilitation Robot

With the development of social economy,people’s pursuit of rehabilitation treatment is increasing,which promotes the rapid development of rehabilitation robots.The combination of rehabilitation robot and cable-driven technology makes the robot simple in structure with a high flexibility and a large workspace enabling a safe human-machine interaction.Through the research on the domestic and foreign development status of cable-driven rehabilitation robots,and investigating the robot zero calibration technology and control method,the paper designs a cable-driven rehabilitation robot for lower limb rehabilitation,performs zero calibration analysis and simulation control analysis,and conducts experiments to verify the theoretical analysis.The main research work is as follows:Based on standard of the human dimensions and the normal gait trajectory of the lower limbs,the body structure of the cable-driven rehabilitation robot was designed.According to the tension condition of the cable,the number and distribution of cables required for the robot are derived,and the configuration of the cable-driven rehabilitation robot is determined.Lagrange method is used to establish the robot dynamic model and the method of cable tension solution is derived based on virtual work principle.According to the requirements of cable tension,the null space method is used to analyze the wrench closure workspace of cable-driven rehabilitation robot,and then the wrench feasible workspace is solved.Finally,an improved genetic algorithm is used to optimize the configuration of the cable-driven rehabilitation robot.In order to improve the accuracy of cable-driven rehabilitation robot,based on the calibration steps of modeling,measurement,parameter identification and error compensation,the zero position error of the cable-driven rehabilitation robot is calibrated.Firstly,the zero error model is established;secondly,the optical 3D motion capture system is used to measure the robot data;then,MATLAB is used to calculate the data to obtain the zero calibration parameters;finally,the theoretical parameters are compared to adjust and compensate the zero position of the cable-driven rehabilitation robot.At the same time,the measurement application software Cortex is developed by MATLAB to realize online data transmission and zero position parameter identification,and the zero position calibration of cable-driven rehabilitation robot is completed through experiments.Finally,the control strategy of iterative learning is proposed for the nonlinear,strong coupling and high repeatability cable-driven rehabilitation robot.The basic theory of iterative learning control is introduced and the convergence of different iterative learning laws is analyzed.Under the premise of zero initial error,the open-loop D iterative learning control simulation experiment was carried out for the cable-driven rehabilitation robot,and the influence of different controller parameters on the control algorithm was analyzed.Based on the simulation of open-loop D iterative learning control,the trajectory tracking experiment of cable-driven rehabilitation robot was carried out,and the experiment results prove the feasibility of the iterative learning control.