Research On Vehicle Adaptive Cruise Control System Based On Millimeter Wave Radar

With the progress of the times and the development of science and technology,the automatic driving vehicle has become the focus of attention.Self driving vehicles should have basic functions such as peripheral environment perception,autonomous navigation and location,Adaptive Cruise Control(ACC)and so on.Among them,ACC system is the most important to ensure the safe driving of vehicles on the road,so the research on ACC system has broad prospects and significance.The main contents of this thesis are as follows:Firstly,the overall scheme of ACC system is designed,which is divided into information acquisition module,decision control module and vehicle control module.The sensor layer in the information acquisition module is designed.The advantages and disadvantages of different millimeter wave radars are compared.The modulation scheme that is most suitable for this thesis is selected.It is found that the traditional triangular signal transmission waveform has problems in multi-target recognition.The decision-making layer in the decision-making control module is designed,and the longitudinal safe distance model of ACC system is established.Aiming at the problem that traditional PID control can only deal with simple car following conditions,model predictive control(MPC)is adopted to meet the control requirements of ACC system for different working conditions.Secondly,aiming at the problem that the traditional triangle transmitting waveform can not recognize multiple targets,a combined transmitting waveform is proposed,and a multi-target comparison matching algorithm is designed to eliminate the false targets in the signal.In order to solve the problem of spectrum leakage when the traditional fast Fourier transform(FFT)is used to process if signal,this thesis uses two-dimensional all phase fast Fourier transform to improve,and proposes an improved constant false alarm rate algorithm to deal with the false alarm caused by clutter interference in signals.The simulation verifies the effectiveness of the above algorithm.Then,in order to solve the problem that the surrounding environment interferes with the information collection,the Kalman filter algorithm is used to track the vehicle in front.An adaptive cruise controller based on MPC is designed to adjust the desired acceleration in real time according to the motion relationship between the vehicle and the front vehicle.Based on fuzzy control,the weight coefficient is adjusted in real time to realize the switching of comfort speed change or safety speed change under different driving environment.The effectiveness of the system design is verified by the joint simulation of Car Sim and Simulink.Finally,experiments were carried out indoors and outdoors to measure the distance and velocity of multiple targets.Through the analysis and processing of the data collected by the radar,it can accurately measure the distance and speed of multiple targets,and the performance meets the design requirements.