Study Of Electronic Stability Control Based On Layered Optimization

In recent years automobiles have been popularized rapidly in the worldwide. Automobilespromote the living standard of people and the social development, but at the same time they alsobring a series of social problems including traffic safety. Electronic Stability Control(ESC) caneffectively reduce the incidence of traffic accidents which is the newest technology in the field ofactive safety. By controlling the braking force to produce the adequate yaw moment, it can keep thestability of the automobiles even in the extreme conditions. This thesis focuses on the research ofESC control theory and method and also the experiment method in the development of ESC.First the review of the development of ESC is given. The basic principle of ESC and the layeredcontrol structure is introduced, which consists of the upper motion controller and the bottompressure controller. The current research status at home and abroad is also presented.Nonlinear vehicle model is established in veDYNA based on Simulink development environment.The cause of the car instability in extreme conditions is analyzed in the “driver-vehicle-road”closed-loop system by simulation test. The simulation results of the nonlinear model and the2DOFslinear model are compared. Then the deficiencies of the2DOFs linear model in the ESC controllerdesign is discussed, which shows that it is necessary to introduce the adaptive cornering stiffness inthe upper motion controller design.Vehicle state estimation is an important research content in the ESC control system. Front/rearcornering stiffness always changes in the car life cycle. This thesis proposed an estimation method offront/rear cornering stiffness based on the available sensors in the car. In order to describe the tirelateral force accurately even when the tire sideslip angle is large, the adaptive cornering stiffness isintroduced in the estimation model by the estimated tire lateral force. This estimation model is alsoused to achieve the better estimation of vehicle sideslip angle.The stable steering characteristic in the linear region and the influence of the changed tireproperties are analyzed. The feedback control coupled feedfroward control is utilized in the uppermotion controller. The performance of ESC with the changed tire properties is optimized. Themulti-model control theory is applied in the feedback controller design. Taking the adaptivecornering stiffness as switching parameter, the designed multi-model global controller can furtheroptimize the performance of ESC because of its robust and adaptive characteristic.By comparing the existing ESC test bench domestic and overseas, the solution which is based onthe NI PXI and veDYNA is chosen. Then the entire “driver-vehicle-road” closed-loop driveenvironment is established. The proposed upper motion controller is verified by rapid control prototype in the ESC test bench. Meanwhile, this test bench system can also lay basis for thedevelopment of real product to increase efficiency.