Research On Robust Tracking Optimal Control Of Lower Extremity Exoskeleton System

Today,with the continuous development of science and technology and the continuous improvement of social manufacturing level,people pay more and more attention to their own health while meeting their own needs.The improvement of human living environment can not be separated from the growth of industry,and the related science of control occupies the main position in industrial development.With the development of high-end industry,including the rehabilitation exoskeleton robots,Industrial robot,mechanical arm and so on,some simple industrial control algorithms have been difficult to meet the growing performance requirements.Exoskeleton robot not only has a wide range of research in the field of medical treatment,but also attracted more and more attention in the field of military,industry and other research applications.Countries around the world have carried out in-depth research and application of exoskeleton robot and achieved substantive results.Among them,the control of exoskeleton robots has always been a hot topic.Therefore,in order to ensure the stability of exoskeleton robots,it is necessary to design a stability control scheme for the uncertain lower extremity exoskeleton model.The main contents of this paper are summarized as follows:Firstly,research and analysis on the lower limb rehabilitation with uncertainty and disturbance.According to the simple exoskeleton model,the coordinate system is established.The stress analysis has been carried Through the angle change and time-varying stiffness when the joint moves,and the corresponding coordinate system is established.According to the energy conservation,the corresponding Lagrangian kinematic equation is obtained.In order to simplify the idea,the system is linearized,and the uncertain term and interference term are introduced,which makes the study of exoskeleton control more simple and convenient.In this case,the state observer is introduced to observe the state of the lower limb rehabilitation system,and then the robust controller is designed.Because the system contains uncertainty and interference,a state observer is designed to observe and analyze the state of the system,then a robust controller is designed to consider the impact of interference on the system,and use the relevant linear matrix inequality(LMI)method and the Lyapunov stability principle are used to study the stability analysis.The simulation results show that the controlstrategy can not only make the lower limb rehabilitation system stable,but also make the lower limb joint flexible to improve the comfort.Finally,for the control problem of exoskeleton system with model uncertainty,a robust optimal tracking control method is proposed.In order to obtain configurable stiffness in exoskeleton flexible control,the design of robust tracking controller is expanded under time-varying stiffness.This method can effectively control the exoskeleton joint with time-varying stiffness,enhance its flexibility and have the function of keeping performance,so as to ensure the quality and safety of the exoskeleton joint.And then using MATLAB to analyze the effectiveness of the designed control strategy for the lower extremity exoskeleton system.