Study On The Integrated Control Method Of ESP/ABS Based On The Leader-Follower Differential Games

Since 1970s, both vehicle companies and correlative experts make unremitting efforts to enhance active and passive safety. With the social development and technology advancement, unaided operation of single controller is incapable to satisfy people's demand on the performance of whole vehicle, and integrated control is the trend of vehicle control technology. Advanced vehicle chassis control technology has very important effect on the improvement of vehicle safety. Therefore, the integrated control problems of ABS and ESP which are two important systems in vehicle chassis is studied in the paper, and based on these, some active explore is done to the new methods of vehicle integrated control. Nowadays, there are many researches on the vehicle integrated control in home and abroad, but there are also many problems. For example, the integrated control can be considered as optimized problem of multi-objective under usual condition, for this problem, the traditional method is to adjust the targets thought the distribution of the weight coefficient of each target. But in fact it is difficult, and has much subjectivity.Based on the above problems, the differential games theory is used to the vehicle integrated control, and many experiments is done based on the ESP and ABS integrated control system, the detailed works is shown as the following:1. The differential games theory is used to the vehicle integrated control. First of all, start with the vehicle system dynamic, the infection and restrict of the two subsystem of ABS and ESP is analyzed, it is found that under special conditions, such as when high speed and emergency steering, there will be conflict between the two subsystem, and it need to adjust. Secondly, based on many references and the compare and analysis of different control theory, it is found that there are many disadvantages in the traditional control methods. Therefore, the leader-follower differential games theory is used to the vehicle integrated control.2. The vehicle model is established. Because different tyre model have different effect on the vehicle performance, start with the tyre model, through the compare, the difference between simplified model and standard model of Magic Formula is little. the simplified model could satisfy the demand of the research, therefore it is used as the tyre model in this paper. Then, start with the vehicle system dynamics and consider the research demand, after the study and analysis of the vehicle model, the nonlinear vehicle model with 7 degrees of freedom is established. The vehicle nonlinear is considered in the model, which could express the nonlinear dynamics characteristic very well.3. Three integrated control system are established. First, the target function of ABS and ESP is established. The limit cycle method is used to calculate the reference value of the body yaw rate and the body side-slip angle, which could judge the dangerous state of the vehicle in time. Using the limit cycle method, vehicle could revert to the stable state with little brake energy, when there are dangerous conditions. Secondly, the integrated control system of ABS and ESP is established, which could satisfy the brake performance under the premise of guaranteeing the steering stability of vehicle system to satisfy the special demand of vehicle steering stability under special conditions. Thirdly, the integrated control system of ABS/ESP and LQR are established for the compare experiments. Finally, the control system is realized on the platform of MATLAB/Simulink.4. The experiment validity is done to the integrated control system, and the experiments results are analyzed. It is proved that different position of leader and follower will have great effect on control performance for the integrated control system of ESP/ABS and ABS/ESP. It is known from the analysis of the experiment that the control effect of the integrated control system of ESP/ABS is much better than the integrated control system of ABS/ESP, but the brake performance of the latter is in the ascendant. Furthermore, it is known from the analysis of the experiment of the integrated control of leader-follower differential games and the optimal integrated control of LQR that the leader's performance could stand out without the enactment of the weight coefficient between the leader and follower and the performance of the follower could also be satisfied, which show the particular advantage of integrated control of leader-follower differential games.