Co-simulating Study On The Vehicle's Active Suspension Based On ADAMS And MATLAB

The suspension system is one of the most important components of the vehicle, which connects the wheel and vehicle body flexibly. The suspension system transfers the force and the torque between the vehicle body and the wheel, and reduces the vibration that is brought by impact force. The suspension is a very complex assembly, which is very diffcult to reach perfection, because it should satisfy the requirement for the ride comfort and handling stability, and these two properties are interrelated and mutual constraints. Nowadays, most vehicle still adopt passive suspension. Despite experienced many years of development, this technology has been more mature and perfect. However, due to structural constraints, the passive suspension can no longer satisfy people's request of vehicle suspension performance. Therefore, active suspension which uses electronically controlled technolog has received wide attention. It is able to provide optimal feedback control according to various road input and actual working condition to maintain optimal overall performance indexes. Active suspension is the inevitable trend of development.At present, the most design study for vehicle active suspension is generally based on simplified mathematical model of suspension. The exactitude of mathematical model has great impact on the study results of active suspension. Sometimes, the exact mathematical model is too difficult to build, and also too complex to research. To solve this problem, the dissertation builds the 2-DOF active suspension mechanical model based on ADAMS software, and do some research of control strategy on this basis. The purpose of this thesis is to improve the vehicle ride comfort and handling stability, especially focus on the adaptability and intelligent of active suspension. The pavement condition is complex and changeable, therefore, to improve adaptive and intelligent of active suspension are of great significance. At the same time, because the mechanical model of active suspension is closer to the actual vehicle suspension, the introduction of active suspension mechanical model has a very large value of the theoretical and practical for active suspension development and application.This thesis mainly combined the Jilin University 985 automobile innovation project"The research on large working space of active and semi-active suspension"and ministry of the new century talents funded projects"The research on the technology of the inertial control active/semi-active suspension". Targeting to a particular vehicle model, the study purpose of this dissertation is to improve the vehicle ride comfort and handling stability, especially to improve the adaptability and intelligent of active suspension.Below is the main job and achievement of the dissertation:1.The purpose, mission and significance of this dissertation are mainly introduced. Make an overall introduction to the suspension, including its composition, function, classification, performance evaluation, as well as its control algorithm, etc. Describe the development course of active suspension, as well as the international and native development trends of active suspension. The dssertation introduce the significance of the co-simulation that based on MATLAB and ADAMS. Finally, it list the goal and mission of this dissertation.2.The dissertation analyzes the suspension's effect on ride comfort and handling stability of the vehicle, expounds the suspension performance evaluation index. It builds the road input model, and expounds the road surface roughness as well as the power spectrum of it. This dissertation uses Gauss white noise as a random road input, and builds its mathematical model. It Establishes the 1/4 vehicle 2-DOF dynamic model based on passive and active suspension respectively. With the analytical method of the state space, it establishes the state equation of the system. At last, it builds the transfer function based on passive suspension.3.The dissertation introduces the ADAMS software simply. With the ADAMS software, the dissertation builds the 1/4 vehicle 2-DOF mechanical model based on passive and active suspension. Then, using the ADAMS/Control module, the dissertation sets up the communication links between ADAMS and MATLAB.4.The dissertation researches the active suspension control strategy based on fuzzy control strategy, and takes a reasonable improvement on this basis. The dissertation combines the fuzzy control strategy with the adaptive PID control strategy, then, it obtains the adaptive fuzzy PID controller. This controller combines the advantages of fuzzy control and PID control, therefore, it has better control effect. Additionally, the dissertation introduces the correction factorαbased on fuzzy control strategy, and designs the active suspension which has the correction factor of fuzzy controller. According to different working conditions, it can adjust the proportion between the error E and the error rate EC on line, so that the fuzzy control rules can be adjust according to actual working conditions. This controller makes active suspension more adaptive and better control.5.The dissertation imports the passive and active suspension mechanical model which are built in ADAMS software to MATLAB. According to different control strategy, the dissertation sets up the simulation model, using the imported ADAMS documents as a sub-system module, then, performs co-simulation. The dissertation obtains simulation curve of passive and active suspension based on different control strategy, and takes comparison and analysis. The results prove that the fuzzy control strategy and its two improved control algorithms are accuracy and effectiveness. The dissertation conducts simulation analysis based on the passive suspension in the framework of frequency domain. By changing the suspension design parameters, the dissertation obtains the changing law of suspension's three main performance indicators.6.After analyzing the co-simulation datas, the dissertation gets the conclusions as follows: In improving body acceleration, fuzzy control, adaptive fuzzy PID control and with correction factor of the fuzzy control reduce the body acceleration respectively 24.24%, 37.545% and 42.87%; In improving suspension working space, fuzzy control, adaptive fuzzy PID control and with correction factor of the fuzzy control reduce the suspension working space respectively 27.5%, 32.5% and 37.5%; In improving dynamic tyre deformation, fuzzy control, adaptive fuzzy PID control and with correction factor of the fuzzy control reduce the dynamic tyre deformation respectively 27.344%, 31.93% and 30.045%.The simulation results prove that the improved two control strategy have better control effect than traditional fuzzy control strategy in the ride comfort and handling stability aspects. Especially, with correction factor of the fuzzy control can improved adaptability and intelligent of active suspension better. The study achievement in this paper plays an academic and practical part in development and application of active suspension.