| With the rapid growth of the world financial market and the rapid development of the automobile industry,the rapid increase of car ownership makes traffic accidents become a social focus.So driving safety is more concerned.Adaptive cruise control in active safety system can solve these focus problems more effectively and reasonably.Adaptive cruise control system can reduce traffic accidents caused by wrong driving and fatigue driving as much as possible,and it can also improve the ride comfort of passengers.The adaptive cruise control system is studied by theoretical analysis and simulation verification.First of all,taking the adaptive cruise control system as the research object,the overall design of its control functions is carried out,and the components and functions of each part are defined;according to the overall scheme of the adaptive cruise control system and the functional requirements of the design cruise control system,the overall technical route and control structure are planned;in order to better adapt to the complex driving Under the working condition,the safety distance model integrates the CTH(fixed workshop time interval)and VTH(variable workshop time interval),which can better ensure the control accuracy.It can effectively improve the dynamic performance of distance control on the premise of ensuring the safety and stability of driving.Secondly,according to the needs of the cruise control system,the corresponding vehicle dynamics model is established according to the real vehicle data,and the vehicle dynamics model is established in the Car Sim 2018 software,and the corresponding configuration of Car Sim is carried out according to the joint simulation of the three software.Because of the emphasis on the longitudinal motion of the vehicle,the default settings are adopted for the system models such as steering system and suspension system which have little influence on the longitudinal control of the vehicle.After the vehicle dynamics model is set up,the ACC test scene and sensor model are established by using Pre Scan software.Then,cruise control uses the upper control and the lower control to simulate and analyze the different driving conditions of the vehicle.In Matlab / Simulink,the layered cruise controller is designed and built.The decision layer is the upper controller and the executive layer is the lower controller of the system.The working modes of the decision layer are divided into three modes: constant speed cruise control,following cruise control and anti-collision control.According to PID control Based on the principle and fuzzy control theory,the upper level controller of cruise control and the upper level controller of following distance keeping are designed.The design of the upper level controller of collision avoidance is based on TTC algorithm of collision time and optimized appropriately.The executive layer mainly consists of acceleration and braking switching logic,driving model and braking model,so as to achieve the tracking control of the upper controller.Realize vehicle cruise control function.Finally,the developed ACC system control strategy and algorithm are applied to the typical working conditions for simulation and verification.Through the joint simulation of MATLAB / Simulink,Car Sim and Pre Scan,the advantages of each software are fully exerted.Finally,the whole cruise control is analyzed and verified.The test scenario and sensor model configuration are established by using the Pre Scan software,and the vehicle dynamics of Car Sim is used The model can output many parameters and the model is accurate.According to the simulation results,the control accuracy of the designed cruise controller is high,which can achieve cruise control and following cruise with collision avoidance function at the same time.Make the car have better tracking,comfort and safety. |
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