Research On Radar Modeling For Vehicle Intelligence

Intelligent vehicle undoubtedly is not only the current research hotspot in the field of automotive,but also the inevitable development trend of automotive industry.The problems of high cost,long development cycle,poor repeatability and especially the safety risks faced by in-vehicle field experiment in the development process of Advanced Driver Assistance Systems(ADAS)highlights the importance of automotive intelligence simulation platform equipped with virtual driving environment and a rich variety of sensor models.However mature commercial vehicle simulation software often pay more attention to the dynamic performance of a single vehicle and be weak in the interactions between vehicles and driving environment.Therefore this article intended for research on modeling millimeter wave radar for vehicle intelligence has positive significance.So far the approach of 3D ray tracing is widely adopted to simulate the propagation channel of radar electromagnetic beam in the automotive millimeter wave radar modeling.The calculation burden of this approach is heavy and make so much simplification in order to adapt to the automotive dynamic application that the meaning of adopting this approach is fading.As to the simulation of RF front end,electromagnetic circuit simulation software is commonly used but it cannot be embedded into the virtual environment platform,which defeats the intention of this paper oriented by the requirements of intelligence vehicle simulation.Based on the sufficient deep research on the state of the art,this article presents a novel combined geometric and physical modeling method on automotive millimeter wave radar.The geometric method belongs to function model,which simplifies the radar detection process into a geometric problem without taking the physical components and working mechanism of radar into consideration.The advantage of geometric model is time-saving while the disadvantage is idealization of model output.Therefore the physical model simulates echo signal processing and adds noise to make the model output more realistic on the basis of geometric model.The main work and achievement of this article are as follows:(1)There is no longer the conception of ray in the geometric model presented.Discretize the target objects in the 3D scene into a set of predefined points that capture the major characteristics of the object shape,abstract the beam radar fires into an elliptic cone,compute the intersection of the radar cone and point set in the scene and exclude the blocked points,thus turning the radar detection problem into a geometric problem,which has been analyzed in detail step by step.The geometric model focus only on geometric calculation taking no consideration of the physical components and working mechanism of radar with the advantage of fastness and the disadvantage of idealization.(2)According to the principle of Linear Frequency Modulation Continuous Wave,the physical model presented simulates all the beat signal in the time domain generated by all the target objects in the scene,contaminate the signal by adding noise,turn the signal into frequency domain by 2D Fast Fourier Transform,set the Constant False Alarm Rate threshold,calculate the more realistic target information based on the position of peaks in the frequency spectrum and output the radar detection results at last.In this article,the signal processing principle under modulation format of LFMCW is analyzed and performed mathematical derivation in detail and is validated by the use of MATLAB scrip as well.(3)The combined automotive millimeter wave model presented is also integrated into the virtual environment platform Pano Sim,which is implemented in three levels,function model(corresponding to the geometric model),power attenuation model and noise model(corresponding to the physical model).The power attenuation model is the comprise of the other two,which considers the effect of radar equation only on the basis of geometric model and modifies the model output further so as to achieve the balance between computation efficiency and model fidelity required by different development application.An ACC Demo is also built by means of Simulink blocks to test if the model integrated in the software environment runs smoothly.The ACC controller realizes the two layer control and get the good simulation results,proving the proposed radar modeling method is valid and effective.