Forward-looking Imaging Method And System Design Of Vehicular Millimeter Wave Radar

Millimeter wave radars are critical parts for Advanced Driver Assistance System(ADAS)and autonomous vehicles.Because it has the characteristics of steady detection,small device size,immune to weather thus can work around the clock.Unlike synthetic aperture radar(SAR)imaging,which can only be used in the side-looking or squint side,multiple-input multiple-output(MIMO)has been introduced into the vehicle-mounted forward-looking imaging.It improves the resolution performance by changing the array configuration.Over the last few years,problems like low resolution and high sidelobe have existed in terms of conventional vehicle-borne millimeter wave radar imaging methods.What’s more,current super-resolution algorithm needs to decompose the data covariance matrix,with complicated computation and long-time imaging,difficult to be real-time.According to the previous problems,this paper does the following things:1.The application of delay and sum(DAS)beamforming algorithm to vehicular millimeter wave radar will lead to low resolution and noticeable sidelobe.To enhance the efficiency of beamforming algorithm and suppress sidelobe,An imaging method based on Kaiser weighted FFT beamforming is proposed.Firstly,the distance information of the aim is acquired by one-dimensional FFT,and then weighted by Kaiser window.The main lobe is narrowed and the side lobe is reduced by adjusting the parameters β.Finally,the FFT algorithm is directly applied according to the Fourier characteristics of the steering vector to avoid the delay multiplication and summation of each element signal,thus reducing the amount of calculation.Simulation and experimental results verify the effectiveness of the method.2.To solve the issues of high computational complexity,long imaging time and barriers in real-time engineering in the super-resolution algorithm of the vehicle-borne Millimeter Wave FMCW MIMO radar,a fast implementation method of iterative adaptive algorithm(IAA)for high-resolution imaging is proposed.In this method,firstly,the one-dimensional range profile of the target is obtained by FFT,then the IAA data covariance matrix and its inverse matrix are decomposed by FFT operator and Gohberg-Semencul(GS)factorization for each distance unit,and the iterative value of IAA is calculated by fast Toeplitz matrix vector multiplication.The real-time performance of IAA estimation of the angle scattering coefficient is improved while the high resolution is ensured.The simulation and experimental results verify that the fast iterative adaptive algorithm(FIAA)can obtain the same high resolution imaging effect as IAA.Meanwhile,we reduce the computing complexity to cut down the running time of the algorithm.3.A forward-looking imaging system based on FMCW MIMO system for vehicle-borne millimeter wave radar is brought up.The scheme uses Ti awr1843 evaluation board,dca1000 data acquisition card and PC to build the hardware platform of the system,and then controls mm Wave studio to set the radar working mode and transmitting waveform parameters to meet the basic needs of target imaging through the GUI interface developed by MATLAB software.After the system initialization and parameter configuration,dca1000 is used to realize the process of data acquisition and storage.The collected data is processed by calling the signal processing module in MATLAB,and finally the imaging results are displayed in the display area of the interface.Through the verification of outdoor experiments,the range angle two-dimensional real-time imaging of targets in different scenes can be realized.