【作者】 杨晨；

【导师】 苏涛； 路志勇；

【作者基本信息】 西安电子科技大学 ， 工程硕士（专业学位）， 2021， 硕士

【摘要】 现如今,随着汽车的普及,交通事故频发已经成为人们愈来愈关注和希望解决的问题。车载雷达的出现和应用可以有效的避免事故的发生。同时,近年来飞速发展的自动驾驶产业,也对车载传感器的性能提出更高的要求。因此,对车载毫米波雷达的研究具有巨大的潜在价值和现实意义。随着集成技术的发展,FPGA不仅具备了小型化、低功耗等优势,其成本也在不断降低。FPGA在保留其通信接口多样化以及并行计算等传统优势的同时,还集成了大量的软核和硬核,已经可以独立的完成雷达的信号处理工作。因此,基于FPGA实现车载雷达的信号处理系统将成为未来的趋势。本文基于锯齿波调制的FMCW的毫米波雷达基本工作原理,对两类可以提高雷达信号处理系统性能的算法进行了研究——速度扩展算法和高精度DOA估计算法。其中速度扩展算法包括了基于Doppler相位偏移补偿的速度扩展算法以及基于中国剩余定理的速度扩展算法。前者可以把雷达的最大无模糊速度增大一倍,缺点是要求雷达必须采用TDM MIMO的工作模式。后者对最大无模糊速度的扩展能力优于前一种算法,但是需要依靠多帧的数据进行速度扩展,降低了雷达刷新率。对MUSIC算法和CAPON算法两种高精度DOA估计算法进行了研究和算法性能分析。两种算法可以有效的提高雷达的角度分辨率。它们的性能除了受雷达孔径的影响外,还受输入信号的快拍数和信噪比的影响。当输入信号相同时,MUSIC算法的性能优于CAPON算法。但是MUSIC算法的计算量更大,对输入信号信源个数估计的准确性也影响其性能。除此以外,还对空间平滑算法和恒虚警率算法进行研究,并在AWR1642中实现了上述的部分算法。本文根据FMCW雷达的工作原理以及雷达最终的指标,设计了可用于测距、测速和测角的车载雷达硬件平台和信号处理系统,并确定了信号处理各环节的参数。在MATLAB中对信号处理系统进行仿真,验证了本文设计系统的可行性。同时在MATLAB中构建了一个可以自定义目标参数的回波信号模型。该模型的数据还应用于验证信号处理系统在FPGA中实现的准确性。最终本文基于Xilinx的xc7k325tffg676-2型号的FPGA实现了具备多目标测距、测速和测角功能的车载雷达信号处理系统。下一步,还需要在FPGA中完善对前端射频芯片的控制模块以及测量结果的输出模块,还可以尝试在FPGA中实现扩展算法以提高雷达性能。更多还原

【Abstract】 Nowadays,with the popularity of cars,the frequent occurrence of traffic accidents has become a problem that people pay more and more attention to and hope to solve.The emergence and application of automotive radar can effectively avoid accidents.At the same time,with the rapid development of auto driving industry,the higher performances of the on-board sensors are required.Therefore,the research on vehicle borne millimeter wave radar has great potential value and practical significance.With the development of integration technology,FPGA not only has the advantages of miniaturization and low power consumption,but also its cost is decreasing.FPGA not only retains its traditional advantages such as diversity of communication interfaces and parallel computing,but also integrates a large number of soft and hard cores.It can complete radar signal processing independently.Therefore,the signal processing system of vehicle radar based on FPGA will become the future trend.Based on the basic working principle of sawtooth modulated FMCW millimeter wave radar,this paper studies two kinds of algorithms that can improve the performance of radar signal processing system.They are velocity expansion algorithm and high-precision DOA estimation algorithm.Velocity expansion algorithm includes velocity expansion algorithm based on Doppler phase offset compensation and velocity expansion algorithm based on Chinese remainder theorem.The first algorithm can double the maximum unambiguous speed of radar.But its disadvantage is that the radar must adopt TDM MIMO mode.Another algorithm is better than the former in the ability to expand the maximum unambiguous speed.But it needs to rely on multi frame data for speed expansion,which reduces the radar refresh rate.MUSIC algorithm and Capon algorithm are studied and their performance is analyzed.The two algorithms can effectively improve the angle resolution of radar.Their performance is affected not only by the radar aperture,but also by the snapshot number and SNR of the input signal.When the input signals are the same,the performance of MUSIC algorithm is better than that of CAPON algorithm.However,MUSIC algorithm has higher complexity.And its performance is affected by the accuracy of source number estimation.In addition,the spatial smoothing algorithm and CFAR algorithm are also studied.Some of the above algorithms are implemented in AWR1642.According to the working principle of FMCW radar and the final performance of radar,this paper designs the hardware platform and signal processing system of vehicle borne radar which can be used for range,velocity and angle measurement.This paper determines the parameters of each link of signal processing.The simulation of the whole signal processing system in MATLAB verifies the feasibility of the system.At the same time,an echo signal model which can customize the target parameters is built by MATLAB.This data model is also used to verify the accuracy of the signal processing system in FPGA.Finally,based on xc7k325tffg676-2 FPGA,the signal processing system of vehicle radar with multi-objective ranging,speed measurement and angle measurement functions is realized.Next,we need to design the control module of front-end RF chip and the output module of measurement results in FPGA.We can also try to implement extended algorithm in FPGA to improve radar performance.更多还原