Path Tracking And Longitudinal Following Control For An Intelligent Platoon

During the past decades, with the rapid development of social economy, science and technology, the developed countries of the world have established gridlocked traffic. But an obvious fact is the growth speed of vehicles has far exceeded that of roads and other traffic facilities. Cars bring modern civilization and pleasure to people, but also have many negative effects on human life and property. Through an intelligent platoon, vehicles driving in line can be realized, road traffic flow be improved, the number of traffic accidents be decreased, environmental pollution be reduced and energy be saved. At present, it is a significant hot research issue to investigate the control problem of an intelligent platoon. In addition, delays are widespread and inevitable phenomenon in nature. The so-called delay refers to the delay in the process of signal transmission, which may exist in the internal state of a system, control input and output. So, under normal situation, an intelligent platoon system can be affected by such delay and the system performance may be reduced. Therefore, it is important to investigate the longitudinal control for the intelligent platoon with delay both in theory and practice.The main results in the dissertation are as follows:In chapter 1, the background and significance of this thesis are introduced in both theory and application. And the research situation at home and abroad is recalled.In chapter 2, the problem of path prediction-based optimal tracking control for an intelligent platoon is investigated. By introducing a vehicle kinematics preview model, the future position of an autonomous vehicle was estimated. And a fast path prediction algorithm in highway environment was presented to derive the preview position of the target path. To implement the path tracking, then, an optimal feedback controller based on the prediction error is designed. Finally, simulation results show that the proposed optimal controller can guarantee that an autonomous vehicle has better path tracking performance on the speed of less than16m/ s.In chapter 3, the problem of longitudinal following control for an intelligent platoon under sampling mode is investigated. For an intelligent platoon controlling, input data of the controller is the discrete data sampling by the sensor with a certain sampling period. Therefore, the control input delay caused by the sampling period is considered. The sampling control is transformed to the controller with input delay by applying input-delay approach. And the nonlinear time-delay closed-loop control system for an intelligent platoon is established. For the nonlinear time-delay closed-loop control systems corresponding to the intelligent platoon, then, an asymptotic stability condition and the control gain are given in terms of linear matrix inequalities. Finally, the simulation results show that the proposed sampling control method make an intelligent platoon maintain a safe distance and keep the same speed.In chapter 4, the main results of the thesis are concluded, and some research issues in future are proposed.