基于FMCW模式的微波车辆检测算法研究及软件实现

发布时间：2018-08-23 12:08

【摘要】：微波车辆检测器具有易于安装维护、可全天候工作、检测能力强等优点,应用前景广阔。论文以调频连续波(Frequency Modulation Continuous Wave,FMCW)模式的微波车辆检测器为对象,围绕其基本原理、系统实现、算法设计等内容展开研究。论文首先阐述了FMCW微波车辆检测技术的基本理论。分析了微波车检器的测距原理,建立了理想状态下三角波调制的中频信号数学模型,并介绍了FFT运算及常用的窗函数,讨论了系统实现过程中存在的干扰。此外,针对实际使用环境中可能存在的杂波干扰,论文探讨了双斜率三角波调制信号提高检测精度的基本原理。其次,论文对FMCW模式的微波车辆检测器进行了系统实现。论文选用IVM-297传感器作为微波收发模块；为实现双斜率三角波调制信号,论文设计了一种利用DDS技术的调制信号发生电路,产生上升沿与下降沿频率不同的三角波,同时设计了可变系数的线性放大电路,对调制信号的幅度进行调节；针对微波反射信号的功率会随着距离增大而快速衰减的问题,设计了衰减补偿电路；论文通过FPGA对系统时钟进行分频,设置采样频率,并利用Linux系统可扩展性强的特点,提出了FPGA+ARM的电路结构,分别讨论了各模块电路的实现；此外,还探讨了FPGA程序和FPGA接口Linux驱动程序的设计。最后,论文对FMCW模式微波车辆检测器的中频信号处理算法进行了研究。为了更直观地显示中频信号及其频谱,同时便于设置相关参数,论文在PC端开发了中频信号处理软件,利用加窗FFT运算对中频信号进行了时频变换；为了验证距离与中频信号频率之间的关系,论文进行了单一目标和多目标的距离检测实验,并对测距公式中的扫频带宽参数进行了标定,确定了车检器的测距精度；论文应用背景差法进行了目标检测,并为实验场景中的模拟车道设置了流量检测阈值；此外,论文还对车型分类的实现原理及实验方法进行了探讨。综上,论文对FMCW模式微波车辆检测器进行了研究与设计,为今后进一步的研究打下了基础。
[Abstract]:Microwave vehicle detector has the advantages of easy installation and maintenance, all-weather operation, strong detection ability, and has a broad application prospect. In this paper, the microwave vehicle detector in FM CW (Frequency Modulation Continuous wave mode is taken as the object. The basic principle, system implementation, algorithm design and so on are studied. Firstly, the basic theory of FMCW microwave vehicle detection technology is introduced. This paper analyzes the ranging principle of microwave vehicle detector, establishes the mathematical model of if signal of triangle wave modulation in ideal condition, introduces the FFT operation and window function commonly used, and discusses the interference existing in the realization of the system. In addition, in view of the clutter interference which may exist in the practical application environment, the basic principle of improving the detection accuracy of the double slope triangular wave modulation signal is discussed in this paper. Secondly, the FMCW mode microwave vehicle detector is implemented in this paper. In this paper, IVM-297 sensor is chosen as microwave transceiver module, in order to realize double slope triangular wave modulation signal, a modulation signal generation circuit based on DDS technology is designed, which produces triangle wave with different frequency of rising edge and descending edge. At the same time, a linear amplification circuit with variable coefficients is designed to adjust the amplitude of the modulated signal, and a attenuation compensation circuit is designed to solve the problem that the power of the microwave reflected signal will decay rapidly with the increase of the distance. In this paper, the clock of the system is divided by FPGA, the sampling frequency is set up, and the characteristic of the expansibility of Linux system is used, the circuit structure of FPGA ARM is put forward, and the realization of each module circuit is discussed respectively. The design of FPGA program and FPGA interface Linux driver is also discussed. Finally, the if signal processing algorithm of FMCW mode microwave vehicle detector is studied. In order to display if signal and its frequency spectrum more intuitively, and to set relevant parameters conveniently, the software of if signal processing is developed in PC, and the if signal is transformed by windowed FFT operation. In order to verify the relationship between the distance and the frequency of the if signal, the distance detection experiments of single target and multi-target are carried out in this paper, and the sweep bandwidth parameters in the ranging formula are calibrated, and the ranging accuracy of the vehicle detector is determined. In this paper, the background subtraction method is used to detect the target, and the threshold of flow detection is set for the simulated driveway in the experimental scene. In addition, the realization principle and experimental method of vehicle classification are also discussed in this paper. In summary, the FMCW mode microwave vehicle detector is studied and designed in this paper, which lays a foundation for further research.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U491.116

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