近年来，随着人们的生活水平越来越好，汽车成为许多人首选的代步工具，车辆事故率也随着汽车数量的增长而增高，给人们造成了巨大的损失。因此，研究可以辅助人们安全驾驶的车载雷达测距系统具有一定的意义，可以更加智能的为驾驶者提供路况信息。

为了能够准确预判行车能否通过路边障碍物，避免出现剐蹭的现象，需提高车载雷达系统测量车身与障碍物之间横向距离的准确性，而横向距离可通过车载雷达与目标之间的纵向距离和角度进行数学运算获得；课题通过减小纵向距离的测量误差，来提高横向距离测量的准确性，对现有测距算法进行改进，将自相关函数法和FFT法相结合，获得更高精度的频率，减小测距误差。在系统设计中，信号的周期对测距范围有较大的影响，为了避免测距时产生的非单值性问题，通过确定探测最远目标的距离来获得信号的周期。在硬件方面，选用带有AD9361的射频板卡和FPGA的Zedboard硬件系统对障碍物进行测距测角，调用FPGA中DDS的IP核，产生线性调频连续波信号，通过硬件系统的接口将信号根据AD9361寄存器中的工作模式传输至FPGA中进行信号处理，得到雷达与障碍物之间的纵向距离和角度；为了获得更加准确的横向距离，对测得的纵向距离进行修正，减小测量误差。

经参数设计和系统仿真验证，证明设计方案的可行性，并在硬件平台上，对系统进行测试。在雷达距离前方目标10m范围内，通过对雷达与目标之间的纵向距离和角度的测量，从而获得与目标之间的横向距离，测得的横向距离误差小于0.1m，达到研究目标的性能要求。

In recent years, cars have become the preferred means of transportation for most people with the improvement of living standards. The vehicle accident rate has also increased with the more and more cars, causing huge losses to people. Therefore, it is of great significance to study the vehicle radar ranging system which can assist people to drive safely and provide road information intelligently.

In order to accurately predict whether the vehicle can pass the roadside obstacles and avoid scratching, it is necessary to improve the accuracy of the vehicle radar system in measuring the lateral distance between the vehicle and the obstacles, and the lateral distance can be obtained by mathematical calculation through the longitudinal distance and angle between the vehicle radar and the obstacle; The subject improves the accuracy of lateral distance measurement by reducing the measurement error of longitudinal distance. It is proposed to improve the existing ranging algorithm by combining the auto-correlation function method and FFT method, and reduce the ranging error by improving the frequency measurement accuracy. In the system design, the period of the signal has a great influence on the ranging range. In order to avoid the non-single-valued problem during ranging, the period of the signal is obtained by determining the distance to detect the farthest target. In terms of hardware,the Zedboard hardware system with FPGA and the AD9361 RF board is used to measure the distance and angle of obstacles,and LFMCW signal can be generated by the IP core of DDS in FPGA . Through the interface of the hardware system,the signal is transmitted to the FPGA according to the working mode in the AD9361 register for signal processing to obtain the longitudinal distance and angle between the radar and the obstacle; In order to obtain a more accurate lateral distance, the measured longitudinal distance is corrected to reduce the measurement error.

Through parameter design and system simulation verification, the feasibility of the design scheme is proved, and the system is tested on the hardware platform.The lateral distance can be obtained by measuring the longitudinal distance and angle between the radar and the target within the range of 10m from the radar to the front target.The measured lateral distance error is less than 0.1m, achieving the performance requirements of the research target.

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