Application Of Linear Matrix Inequality In Magnetorheological Suspension

As a common phenomenon,vibration exists widely in daily life.In the fields of highway,aviation,construction,etc.,vibration is a key issue that needs to be considered.In industrial manufacturing,reasonable vibration reduction is of great significance for improving processing accuracy.Severe vibration can also cause problems such as the reduction of mechanical structure strength and the loosening of connecting parts.In addition,vibration will also generate noise.Large-decibel noise seriously harms the physical and mental health of drivers,and even causes component breakage,endangering driving safety.Therefore,whether the vibration can be effectively reduced is the key to ensuring driving safety.As a new type of semi-active damping system,the vehicle suspension system using MRD has the characteristics of low power consumption and continuously adjustable output damping.In most cases,it has similar performance to the active suspension,so it has received academic research.Wide attention from the world.However,the current MRD has problems such as magnetic particle sedimentation and low precision of mechanical model parameter identification.Related problems still need to be further studied.In the control of the magnetorheological semi-active suspension,four problems must be solved in the control of the magnetorheological semi-active suspension: the expected damping force calculated by the control strategy is not in the range of the MRD output damping force,and when the MRD output damping force The problem of hysteresis,the problem of uncertain structural parameters of the control system,and the robustness of the control strategy to external uncertain disturbances.At present,the level of MRD control theory applied to it is still not high and needs to be further improved.To this end,this paper has conducted the following researches,including parameter identification of MRD mechanical models,modeling and analysis of semi-active suspension systems,and verification and simulation of control strategies.The main research contents include:(1)MRD mechanical performance test and parameter identification.The INSTRON drawing machine was used to test the mechanical properties of the MRD processed by the research group.The advantages and disadvantages of various dynamic models of MRD are analyzed,and the simplified adjustable Sigmoid model is selected as the object of parameter identification.Based on the indicator characteristics and speed characteristics obtained in the experiment,the Levenberg-Marquardt optimization algorithm and the least square method are used to identify the unknown parameters of the simplified adjustable Sigmoid model,and the adjustable Sigmoid model and the accuracy of the identification are analyzed.The simulation research of rheological semi-active suspension provides a strong guarantee.(2)Modeling and dynamic analysis of magnetorheological semi-active suspension.According to the actual road conditions of the vehicle,a random road model and an impact road model are established,and the influence of different levels of roads on the displacement input is analyzed.The characteristics of the 1/4 model of the three-degree-of-freedom semi-active suspension,the six-degree-of-freedom car-chair-human dynamics model,the actual 1/4 vehicle model and the reference model are introduced.The motions of these three models are derived according to Newton’s second law Differential equation.A six-degree-of-freedom vehicle-chair-person dynamic model was built in Matlab/Simulink,and the performance indicators of the dynamic model under random road excitation and impact road excitation were analyzed.(3)Design and simulation verification of vehicle semi-active suspension control strategy.Due to the inaccuracy of the measurement and the quality change during use,this will lead to the uncertainty of the vehicle semi-active suspension system parameters.In order to solve the influence of the parameter uncertainty on the semi-active suspension control,based on the linear matrix inequality(LMI)toolbox A H∞ control strategy with non-deterministic structural parameters is proposed.By reducing the influence of external input on the control output to a certain level,a good control effect is achieved when the parameters of the semi-active suspension system are uncertain;When on the road,in addition to being stimulated by the road,it will also be disturbed by wind,raised sand and gravel.In order to solve the influence of non-deterministic external interference on the performance of the human semi-active suspension system,it is based on the linear matrix inequality(LMI)Toolbox,proposed an interference suppression control(ISC)strategy,by applying the same external interference to the passive suspension and the semi-active suspension using the ISC strategy,to verify the good suppression effect of the ISC strategy on the uncertain external interference.