| With the aggravation of social aging situation,supporting the elderly has become one of the major livelihood issues to be solved urgently in China.The growth of age is often accompanied by the degeneration of nervous system,skeletal system and muscular system to varying degrees,and the elderly are vulnerable to diseases due to the decline of immune system function.Stroke is a high incidence disease in the elderly population,which will cause patients with varying degrees of lower limb motor dysfunction,and has a great psychological and physiological impact on patients.Recently,to help patients with lower limb motor dysfunction to achieve rehabilitation training and free walking,a large number of medical auxiliary equipment have been developed,among which the rehabilitation exoskeleton robot has become one of the research hotspots in the field of rehabilitation at home and abroad.The lower limb rehabilitation exoskeleton is a human-machine integrated rehabilitation equipment.Ideally,the exoskeleton can not only provide support and strength for human movement,but also have the ability to quickly recognize the intention of human movement,which provide a safe and natural rehabilitation training environment for patients.Furthermore,considering that the user is a patient with motor dysfunction,the mass of the lower limb rehabilitation exoskeleton should be lighter and the operation should be more intelligent.The lower limb rehabilitation robot can not only improve the shortage of rehabilitation resources,but also reduce the repetitive and heavy physical work of rehabilitation therapists.At present,there are many problems such as high price,fixed gait and complex operation in lower limb rehabilitation exoskeleton products.Therefore,the development of rehabilitation exoskeleton system with low energy consumption,excellent motor performance and diversified functions is still an urgent problem to be solved in the research of lower limb rehabilitation exoskeleton.In this paper,the biomimetic lower limb rehabilitation exoskeleton with rigid-flexible coupling is taken as the research object,and a safe and comfortable rehabilitation environment is taken as the research objective,and a favorable mechanical structure of the lower limb rehabilitation exoskeleton is designed by comprehensively considering the physiological structure of human lower limb and pathologic gait pattern.A mapping model of human-machine interaction information and motion intention recognition is established to estimate human continuous motion intention accurately.Then,the human-machine cooperative control strategy is constructed to realize the cooperative movement between the wearer and the lower limb rehabilitation exoskeleton.Based on the common problems existing in the current research of lower limb rehabilitation exoskeleton robot,this paper focuses on the structural design of lower limb rehabilitation exoskeleton,the recognition of intention of the lower limb continuous motion of and human-machine collaborative control strategy.The specific research content includes the following aspects:(1)Aiming at the rehabilitation training of stroke patients in the later stage of rehabilitation,a design method of bionic limb rehabilitation exoskeleton robot with flexibility,modularization and lightweight is proposed.Based on the theory of human movement anatomy,the characteristics of healthy gait and pathological gait are analyzed,and the overall design goal of lower limb rehabilitation exoskeleton is established.According to ergonomics and functional bionics theory,the degree of freedom distribution of the lower limb rehabilitation exoskeleton is studied,and the assisted joint is designed to realize the design of the structure of the lower limb rehabilitation exoskeleton.To ensure that the exoskeleton can simultaneously meet the design requirements of safety and lightweight,the ANSYS software is utilized to check the strength of the main stress components of the lower limb rehabilitation exoskeleton,and the mechanical structure is further optimized according to the check results.This design scheme improves the coordination and safety of the human-machine system during the movement of the lower limb rehabilitation exoskeleton robot,and reduces the volume and weight of the exoskeleton.(2)Based on the detailed analysis of the dynamics of lower limb rehabilitation exoskeleton system,the mathematical model of lower limb rehabilitation exoskeleton system is established,and the human-machine coupling model is reasonably simplified according to the biomechanical principle.To evaluate and test the transmission performance of flexible structure in lower limb rehabilitation exoskeleton,flexible shaft transmission tests are carried out in discrete and continuous modes respectively to explore the influence of load size and flexible shaft bending degree on the transmission efficiency of flexible shaft.The virtual prototype technology is exploited to establish the motion simulation platform of human-machine coupling system.The physical properties of the lower limb rehabilitation exoskeleton driving joint with the condition of gait cycle are analyzed in detail through experiments,which provided theoretical basis for the verification of prototype,selection of driving motor and construction of control system.(3)A neural network prediction model with high accuracy and strong robustness is proposed to estimate the intention of continuous motion of the lower limb.Based on the principle of neurophysiology,analyzing the generation mechanism of lower limb motion intention,exploring the correlation between lower limb muscle and joint movement in different motion modes,and three prediction models of motion intention based on neural network are proposed to estimate the continuous motion intention of the lower limb.Aiming at the three training modes of walking,stair climbing and treadmill,the surface electromyogram(sEMG)signals and joint angle signals are collected as motion intention recognition signals,and the correlation between sEMG signals of lower limb muscles and joint angle is given by employing statistical correlation test knowledge.The data with high correlation are selected as the input of the prediction model to carry out the intention recognition experiment of lower limb continuous movement.The feasibility,stability and superiority of the intention prediction model of lower limb continuous movement are analyzed by comparing the experimental results.(4)The lower limb rehabilitation exoskeleton platform system is constructed to scientifically evaluate the performance and effect of the lower limb rehabilitation exoskeleton.The hardware platform of lower limb rehabilitation exoskeleton is designed,including drive system,control system,sensing system and human-machine interaction system.Firstly,for ensure the safety of the experiment,the no-load experiment of the exoskeleton is carried out to verify the tracking performance and dynamic response performance of the exoskeleton.Afterwards,a human-machine interaction control algorithm with active compliance is proposed to increase the comfort of human-computer cooperative motion,and the effectiveness of the algorithm is verified by simulation experiments.Finally,the lower limb exoskeleton wear experiments are carried out for walking and upstairs modes,and the evaluation system of human-machine efficacy performance is established based on subjective indicators and objective indicators.The experimental results demonstrate that the lower limb rehabilitation exoskeleton system performs well in human-machine interaction performance and power performance. |
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