Design Of Full Speed Adaptive Cruise Control System Based On Improved Optimal Control Algorithm

With the continuous increase of car ownership per capita,it is convenient for people’s lives but it also triggers a series of social problems,such as frequent traffic accidents,environmental pollution and energy shortage.The Adaptive Cruise Control(ACC)system based on pure electric vehicles can effectively replace the driver to control the vehicle to drive safely,while saving energy and reducing environmental pollution.It has good research and application value.The road environment faced by the vehicle is complicated,which requires high control performance of the system.Aiming at the problem that the current ACC system cannot take into account both highspeed and low-speed control accuracy and comfort,the main content of this thesis is how to design and implement the ACC system based on pure electric vehicle,so that it can run steadily in the whole speed range and achieve high tracking accuracy.Firstly,after analyzing the needs of the sensing system,the thesis uses IBEO lidar to acquire high-precision target information.The yaw rate of the controlled vehicle is used to develop the discrimination schemes of straight and curved roads,and the target selection strategies under two kinds of roads are designed respectively.After analyzing the demands of the execution system,the pure electric test vehicle is taken as the research object.The longitudinal dynamic model and the inverse longitudinal dynamic model of the vehicle are respectively established through the acquisition of the actual vehicle parameters.In addition,after analyzing the relative state of the controlled vehicle and the target vehicle,the safety distance model is established by introducing the velocity difference between the two vehicles.Secondly,aiming at the problem of target mutation in complex road environment,the thesis divides the working mode of the controlled vehicle into three types: active collision avoidance,cruise control and following the vehicle in front.Considering the safety and comfort,the control algorithm and switching strategy of each mode are established.For the following mode,the linear quadratic optimal control algorithm is used to establish the output tracking system problem.Aiming at the problem that the fixed weight matrix cannot take into account the control accuracy and comfort of the full speed range,this thesis designs the fuzzy controller based on the speed of the controlled vehicle,dynamically chooses the weight matrix coefficients,so as to achieve the optimal control in the full speed range.Finally,the simulation platform of the system is built,and the control effects of the three modes are verified through the joint simulation of Simulink and Carsim.The simulation results of the improved algorithm and the traditional optimal control algorithm are compared and analyzed.The results show that compared with the traditional optimal control algorithm,the average absolute error of the following distance is reduced by 38.65%.By building a real vehicle test platform,the designed ACC system is transplanted to the embedded controller to complete the real vehicle test.The test results show that the ACC system designed in this thesis can achieve good control effect.