Research On Optimization And Control Of Wire Force Of Wire Traction Rehabilitation Robot For Lower Limbs

After entering the new century,with the improvement of people's living standards,more and more attention has been paid to patients with lower limbs motor dysfunction.The research and application of lower limbs rehabilitation robot have also been developed rapidly.Wire parallel mechanism has the advantages of simple structure,small mass,accurate motion track,high space utilization and low energy consumption,and has received more attention.The application of wire parallel robot in the field of rehabilitation medicine can greatly save space,improve the safety of rehabilitation training and reduce the cost of manpower.However,the wire-driven parallel mechanism is a redundant system,and the solution of the cable force has many groups,so it is difficult to optimize the solution.Therefore,a fast and accurate method to optimize the redundant wire force is of great significance.Aiming at the rehabilitation robot of human lower limbs,the main research contents are as follows:According to the skeletal parameters of lower limbs and the kinematic parameters of hip and knee joints of lower limbs in gait cycle,the physiological model of lower limbs and the function of hip and knee joints in normal gait cycle are established.The generalized force equation is established to solve the force exerted on the ankle to realize the gait trajectory in the gait cycle.According to the functional requirements of lower limb rehabilitation training,the basic configuration of the wire-driven lower limbs rehabilitation robot is designed.The structural parameters of the lower limbs rehabilitation robot are improved to increase the working space.For redundant wire-driven force optimization,the minimum variance of wire-driven force is selected as the objective function of optimization.Using generalized inverse optimization to solve redundant wire-driven force,the magnitude of each wire wire-driven force is analyzed.Based on its limitations,a particle swarm optimization(PSO)algorithm is proposed to optimize the wire-driven force.The objective function is established,and the constraint conditions of the wire traction system of the lower limbs rehabilitation robot are processed to make it an unconstrained particle swarm optimization(PSO)model.The parameters of the algorithm are studied.By comparing the improved algorithm and the basicalgorithm to select the appropriate parameters,and comparing the other factors affecting the particle swarm optimization(PSO),the optimal particle swarm optimization(PSO)scheme is obtained.Finally,the redundant wire wire-driven force is solved through the optimal particle swarm optimization(PSO).In order to improve the accuracy of the gait periodic trajectory of the wire traction rehabilitation robot and make the wire output the optimized wire-driven force,force control and position control are adopted for different wire units.The model of DC motor based on wire-driven is established,and the stability of the control methods of each wire unit is analyzed,and the unstable system is corrected until it is stable.Reasonable controller is designed and simulated with MATLAB/simulink to adjust the PID parameters,so that the system can output quickly and stably.Experiments were conducted to verify the wire-driven force output of the lower limbs rehabilitation robot optimized by particle swarm optimization(PSO).