State Observer -based Lateral Control Of A Vehicle

Recently, with the development of science and the progress of technology, vehicles have become indispensable modern transport tool to facilitate the people’s lives. But, it is not ignored that the rapid growth of the number of the vehicles causes a series of problems such as serious environmental pollution, energy consumption, road congestion, and traffic accidents, and even threats human’s lives and properties. Therefore, traffic safety is a timeless and important issue. To deal with such problems, National experts and scholars have made great efforts to study advanced driver assistance systems to reduce properties loss and casualties. Advanced highway system as an important type of advanced driver assistance systems, receives widespread attention. Its basic tasks include longitudinal control and lateral control. Longitudinal control is maintaining a sufficient safety distance between neighboring vehicles by adjusting the following vehicle’s speed. Lateral control is tracking a reference trajectory by adjusting the vehicle’s self-steering. In other words, using a sensor to measure the lateral displacement, calculating correspondingly the steering angle, and imposing a control command to the steering actuator guarantee that the vehicle travels along the road centerline. This thesis mainly studies vehicle lateral control problem. Vehicle lateral control is based on some known states such as sideslip angle and yaw rate. The yaw rate can be measured by a cheap gyro sensor. Due to the high cost of the sideslip angle sensor, we use a Luenberger observer to estimate the sideslip instead of sideslip angle sensor, which highly reduces the cost. Intelligent vehicles with observer-based controllers can effectively reduce the implementing cost while they have the property of lane keeping. Therefore, the intelligent vehicle lateral system with the observer-based controller has practical value.The main work of this thesis is organized as follows:The first chapter introduces the structure and function of Intelligent Transportation Systems, the importance of advanced driver assistance systems, research status of automated highway system, lateral control technology, and the thesis’s main contents.The second chapter considers vehicle lateral stable control on the same road environment where the controller design is based on Luenberger observer. A second-order linear system is used to represent the vehicle lateral dynamic model, and a Luenberger observer is chosen to estimate the sideslip angle. The controller with such an observer is designed to realize that the vehicle runs steady. The observer gain and controller gain are obtained by the pole placement method. Finally, Matlab/Simulink simulation results show that the proposed control method can ensure that the vehicle with the designed controller runs smoothly.The third chapter studies vehicle lateral stable control on the different road environment where the controller design is based on Luenberger observer. The bicyle model is built, the T-S fuzzy membership function is proposed to describe nonlinear tire lateral force, the road uncertainty is modeled by robust control theory, the observer-based controller is designed to make the vehicle run smoothly. The sufficient condition is given in the form of LMI. Finally, Matlab/Simulink simulation results show the effectiveness of the proposed method.The fourth chapter, summarizes the thesis’s work, and predicts the follow-up work.