Study Of H_∞ Robust Controller Of 4WS-4WD Electric Vehicle Based On LMI

Electric vehicle has developed quickly in rencent years. With the development of multimedia technology, steering-by-wire control technology, driving assistance technology, vehicle networking technology and other advanced vehicle technologies, trends of intelligent and electronic vehicle are becoming more and more evident. In this case, the parameters of the electronic system of the vehicle will be uncertain, for example, the parameters of the vehicle system and the controllers are often fluctuant.To solve the above-mentioned problems of four-wheel steering and four-wheel driving (4WS-4WD) electric vehicle, a series of robust H∞, controllers are designed based on linear matrix inequality (LMI) in this paper. Robust H∞ control is one of the hot spots of robust control and can effectively solve the problem of system parameters perturbation. It is excellent to enhance the robustness of the system. This paper mainly completed the following innovative work:(1) Robust H∞ controller is designed to solve the problem that there is parameters perturbation in the system and robust H∞ controller can effectively suppress the perturbation in the system. Control effect oft robust H∞ con roller is better than other control methods, such as pole placement.(2) The robust performance of robust H∞ controller is excellent. However, the control performance is bad because it is sacrificed to get better robust performance. Robust H∞ optimal controller is designed to solve the problem. In other words, robust optimal control can overcome the deficiencies that other design methods sacrifice some performance for the price to guarantee the robustness of the system. Robust H∞ optimal controller can also solve the problem that optimal control relies on interference signal which is strictly limited and precise system mathematical models and these are hard to meet.(3) Most of the methods about designing controllers introduced for 4WS-4WD vehicles are derived with the assumption that the controller parameters are constant. However, in the running process of the actual system, because of word length, conversion accuracy, truncation error of numerical calculation and other factors, the parameters of controller are often fluctuant. The existing design methods of robust controller such as μ synthesize are extremely sensitive to perturbations of controller parameters. At the same time, the parametres perturbation of vehicle controller is not taken into consideration in other papers and controller parameters are very important to vehicle system. Robust H∞ non-fragile controller is designed to solve this problem that controller is sensitive to parameters.