Design Of Electromagnetic Active Suspension And Research On Control Strategies

Vehicle suspension is a transmission device between vehicle frame and vehicle axle,which can not only buffer and reduce shocks and vibrations caused by road excitation,but also ensure the ride comfort and handling stability.In recent years,with the extensive development of vehicle suspension,people pay more and more attention to the ride comfort,handling stability,reliability,safety,needs of passengers,and so on.Due to the advantages of magnetic driving technology,such as non-contact,non-lubrication,fast response and strong controllability,the electromagnetic active suspension using the magnetic driving technology has been widely attention from researchers.This paper proposes a new type of electromagnetic active suspension.It embeds the actuator for the electromagnetic active suspension into the traditional passive suspension,and is composed of the actuator,damper and spring in parallel.When the vehicle is running on the road,the actuator not only provides the active force to control the ride comfort and body posture of the vehicle in real time,but also stores the electromotive force generated by vibrations in the battery after conversion.Therefore,the electromagnetic active suspension ensures the safety of the passive suspension,and also improves the overall performance of the suspension system through magnetic driving technology.The paper firstly elaborates the working principle of the electromagnetic active suspension in detail,the structure of the actuator for the electromagnetic active suspension is designed,its size is optimized,and the final structure is finally determined.The principle prototype of the actuator for the electromagnetic active suspension is built,and the magnetic field characteristic and mechanical characteristic of the actuator for the electromagnetic active suspension are studied in theory,simulation and experimental research.The feasibility,safety and effectiveness of the control strategy are verified by simulations and principle prototype experiments.The main content of this paper is divided into the following six parts:(1)Based on the comprehensive analysis of the existing problems of the electromagnetic active suspension,this paper proposes a new type of electromagnetic active suspension,and describes its working principle in detail.The actuator of the electromagnetic active suspension is designed in structure and optimized in size to determine the final size of the actuator,and the prototype of the actuator is built.(2)Based on the equivalent magnetic circuit method and mesh analysis method,the magnetic field theoretical model of the actuator for the electromagnetic active suspension is established,and the theoretical model of the mechanical characteristics is established based on the magnetic field theoretical calculation.The magnetic field characteristic and mechanical characteristic of the actuator are simulated and analyzed by magnetic field simulation software.The magnetic field characteristic and mechanical characteristic of the actuator principle prototype were measured and analyzed,and the accuracy of the magnetic field characteristic and mechanical characteristic in the theoretical model and simulation analysis is verified.(3)The vehicle body acceleration,suspension working space and tire dynamic load are taken as three performance evaluation indexes of vehicle suspension system,random road excitation and impact road excitation are established respectively.The dynamic models of 1/4vehicle 2-degree of freedom(DOF),1/2 vehicle 4-DOF and whole vehicle 7-DOF of the passive suspension and electromagnetic active suspension are established.Based on PID control strategy,the dynamic simulation analyses of 1/4 vehicle,1/2 vehicle and whole vehicle electromagnetic active suspension are carried out with random road excitation,and compared and analyzed with the dynamic simulation results of those passive suspensions.The control effects of vertical motion,pitch motion and roll motion of vehicle based on the electromagnetic active suspension are obtained.(4)Based on the electromagnetic active suspension of 1/4 vehicle with 2 DOF,the theories of PID control,robust control and pole coincidence placement control strategies are established,and the three control strategies are applied to the electromagnetic active suspension respectively.The three vehicle performance evaluation indexes and the frequency domain response results of the body acceleration are compared,analyzed and evaluated.The simulation results show that the PID control strategy can suppress the body attitude,the robust control strategy can suppress the body acceleration and improve the robustness of the suspension,and the pole coincidence placement control strategy has a certain improvement in driving comfort while restraining the body acceleration,and its response speed is faster.(5)To verify the rationality of the electromagnetic active suspension and the effectiveness of the control strategies,experimental analyses of the principle prototype of the electromagnetic active suspension are tested and analyzed.The principle prototype of the electromagnetic active suspension is built,and the principle prototype,the control system and the follow-up experimental schemes are described in detail.Based on the principle prototype of the electromagnetic active suspension,PID control,robust control and pole coincidence placement control strategies are applied to carry out experiments with multi frequencies and multi amplitudes for the electromagnetic active suspension.The experimental results with sinusoidal excitation of 2mm amplitude and 6Hz frequency as input signal are analyzed.The experimental results show that the PID control strategy can suppress the suspension working space,so that the body attitude can be better controlled,and the anti-interference ability is better.The robust control strategy has a strong comprehensive control effect on the body acceleration and the suspension working space,which reflects the strong robustness.The pole coincidence placement control strategy has a certain effect on improving the ride comfort,and the response speed of the controller is relatively high.Therefore,the real-time,stability and effectiveness of the three control strategies are verified by principle prototype experiments of the electromagnetic active suspension.(6)Finally,the paper summarizes the theories,simulations and research results,and clarifies the innovations of this paper once again.Combining with the current research hotspots of the electromagnetic active suspension and the research results of this paper,the further in-depth researches of the electromagnetic active suspension are prospected.