Design And Simulation Of Active Suspension Controller Based On Half Vehicle Model

With development of modern society and improvement of living standards, automobiles have been the basic means of transportation for people’s daily lives, so people have much higher requirements on their performance. As an important component of automobiles, suspension system’s performance has a great impact on automobile’s steering stability and ride performance. Therefore, and to design a suspension system with sound performance is an important key issue in modern automobile research. Traditional design of automobile suspension has some weakness, such as long designing cycle, high cost, and so on. Designing cycle can be shortened and research cost can be reduced through computer-aided design technology.In the research on the whole structure of automobiles, an automobile is defined as a complicated vibration system with multiple degree of freedom. In theory, the more degree of freedom is taken, the closer the model will be to the reality. But with the increasing of degree of freedom, the design value and the measuring parameter will be increased so that the number of dynamic model’s equation will be increased accordingly. Through the method from simplicity to difficulty and from simplicity to complication, the research was carried out in this paper from four degree of freedom to seven degree of freedom and from passive suspension to active suspension. Meanwhile, the method of connecting automobile’s principle of dynamics to simulation software was taken. Namely, dynamic model was built based on multibody dynamics theory, then its simulation model was built in simulation software, with dynamic simulations carried out. At last, the simulation results were analyzed and compared.First, road surface input model was built and its simulation was carried out. There are two steps:1) analyze road surface input model and build mathematic model,2) build simulation model and carry out the simulation, whose aim was to laid foundation for building suspension’s simulation in latter part of this dissertation. Second, simulation of passive suspension of half vehicle was carried out. Mathematic model of half vehicle model of passive suspension was built mainly on the basis of multibody dynamics theory. Then, system simulation model of passive suspension’s of half vehicle was built by combining road surface input model, based on its mathematic model in MATLAB/Simulink. Meanwhile, the main performance assessment index of passive suspension was researched and analyzed. Third, active suspension’s simulation of half model was carried out. On the basis of research on passive suspension, optimal control matrix was worked out through optimal control algorithm. Active suspension controller’s dynamic model and simulation model of half vehicle was built. Then, by combining mathematic and simulation model of passive suspension of half vehicle, building of simulation model of active suspension of half vehicle was completed. Simulation was carried out and performance change was compared and analyzed so that the improving degree that optimal control theory changed the performance of half vehicle’s suspension system was verified. Fourth, simulation of passive suspension of entire vehicle model was carried out. On the basis of road surface model and half vehicle’s passive suspension model, dynamic model and simulation model of passive suspension of entire vehicle were made with simulation carried out and its result analyzed. At last, simulation of active suspension of entire vehicle’s model was carried out. The design of its controller in entire model was the same as that of half vehicle model. The model building was based on such models:road surface input model, passive suspension’s model of entire vehicle and active suspension’s model of half vehicle and controller model. Finally, the performance improvement degree that optimal control algorithm changed the suspension was compared and analyzed. Research on simulation to automobile suspension system could improve the performance, ride performance and steering stability of automobiles.