The Control System Design Of Lower Extremity Exoskeleton Robot Based On Human Movement Mechanism

As we all know,it was a relatively safe and effective way to improve the lower limb motor function of patients through the nursing and auxiliary training of medical personnel.However,due to the issue of population aging,the growth rate of patients far exceeded the ability of medical staff to provide auxiliary function training for the total number of patients with motor dysfunction.The appearance of exoskeleton robots based on the principles of robotic systems and biomedical engineering has brought the gospel to the majority of patients,which could help patients perform effective rehabilitation training to a certain extent without care.The purpose of designing a lower limb rehabilitation robot was to make patients' lower limbs move or walk like a healthy person through rehabilitation training of exoskeleton robots.Therefore,the gait movement characteristics of the human body could be optimized and used in humanoid controller design and real-time training of a lower limb rehabilitation robot.How to effectively process captured motion characteristics,design humanoid controllers,and apply them to realtime assisted training of lower limb rehabilitation robots had become a research hotspot in the design,which was an effective way to realize humanoid control of the lower limb rehabilitation robot.Therefore,this paper conducted relative research on the dynamic modeling and control system design of the lower extremity exoskeleton robot based on the movement mechanism of the human body.The main research contents include:(1)Dynamics and operational analysis of lower limbs exoskeleton robot based on human motion characteristics.This article used NOKOV three-dimensional infrared motion capture equipment and three-dimensional force measurement platform equipment to collect human gait data and plantar force data.Due to the influence of external disturbance during the acquisition process,the least square method and the least filtering method were used to filter the data.Since the processed data cannot be directly applied to the lower extremity exoskeleton robot as an ideal reference movement,Fourier was used to performs curve fitting through the comparison and analysis of the fitting coefficients and root mean square error of the three methods of Gaussian function,Fourier function and sine function.The fitted curve was used as the reference expected trajectory of the lower extremity exoskeleton robot control system,and the kinematic and dynamic characteristics of the human body were analyzed by the collected data.(2)Dynamic modeling of the lower limbs of a robot-like mechanism.In this paper,the left leg of the lower extremity exoskeleton robot was selected for research.By simulating the structure of a multi-link robot,the dynamic model of the lower extremity exoskeleton robot is derived using the Lagrange equation.The linearization characteristic of the lower extremity exoskeleton robot model was obtained by separating the known parameters and the unknown parameters of the system.(3)Design of lower extremity exoskeleton robot control system based on human motion mechanism.Combined with the study of the movement mechanism of the human lower limbs,the control system of the exoskeleton robot is studied.This paper proposed three methods: linear feedback control based on human comfort,adaptive control based on human comfort,and robust adaptive PD control based on human gait data.The linear feedback control method based on human comfort mainly used the comfort of the lower extremity robot wearing the human body as the objective function to linearize the non-linear system.Aiming at the problem of robot parameter uncertainty,an adaptive control method based on human comfort is used to solve the problem.The inertia parameters of the system could be well identified by the designed adaptive rate.A robust adaptive PD control based on human gait data was used to solve the problems of external disturbance and excessive input torque.The simulation results shown that the control system of the lower extremity exoskeleton robot still having good stability when the system error and the disturbance upper bound were known,and the problem of excessive input torque control in the first two methods was improved.The similarity function verified that the robot motion trajectory was very similar to the human motion trajectory,which objectively indicated the comfort of the human body during wear.The stability conditions were derived using Lyapunov's theorem,and the trajectory tracking characteristics were discussed.(4)Simulation verification of the lower extremity exoskeleton robot control system based on experimental data.In order to verify the validity of the proposed theory,the lower extremity exoskeleton robot control system was used as the reference expected motion trajectory of the lower extremity exoskeleton robot control system,and the lower extremity exoskeleton robot control system simulation based on experimental data was verified.