Study Of Adaptive Integrated Control In Vehicle Electric Power Steering And Active Suspension System

In recent years, kinds of electronic control techniques and sub-control systems are greatly developed and widely applied to improve ride comfort and handling stability of vehicles. However, all these sub-control systems are aimed at improving one performance of a vehicle, but the improvement of the whole performances in a vehicle is still depended on the cooperative work between various sub-systems. Based on this point, this dissertation carries through the study of integrated control in vehicle electronic power steering (EPS) and active suspension system; two sub-control systems directly influence the vehicle's handling stability and ride comfort. Firstly, this dissertation develops the dynamics analysis of electronic power steering system, builds the three-dimension model of a vehicle with EPS, suggests adaptive LQG control strategy and does the simulating study. Based on these researches, this dissertation analyzes the relationship between two sub-systems, EPS and active suspension, sets up the model of a full vehicle, suggests the control scheme based on multi-variable adaptive control integration, and does the simulating calculation. Finally, experiments on test bed and road are performed in a real automobile. Results of these researches indicate that adaptive control can efficiently reduce system's influences caused by model's uncertainties, stochastic disturbances, and quantified measuring noises. Meanwhile, adaptive control can help the steering system acquire excellent performances of power-assisted and portability characteristics; the suspension system has a good performance of reducing vibration, and can improve dynamical character of a full vehicle. During the process of building the system model, this dissertation sufficiently considers the mutual influences and harmony relationships between two sub-systems, EPS and active suspension; more precise calculating results are acquired by simulating calculation; these results are matched with the results of real experiments. Therefore, integrated control of many sub-systems can make up the weakness of control implemented by one sub-system, avoid the mutual disturbances and influences due to many sub-systems control respectively; it can greatly improve and increase the dynamical performances of a vehicle.