脉冲式与相位式相结合的激光测距系统研究

发布时间：2018-04-09 11:33

本文选题：激光测距　切入点：信号发生　出处：《北京化工大学》2015年硕士论文

【摘要】：由于激光具有亮度高、单色性好、方向性好和相干性好等优点,激光测距技术不仅成为空间探测的重要技术,还在大地勘测、振动检测、液位测量等领域获得推广。目前,国内外常用的激光测距仪主要有相位式和脉冲式两种。其中,相位式激光测距仪仅限于用在对精度要求比较高的近距离测量场合,脉冲式激光测距仪仅限于应用在对精度要求低的远距离测量场合。针对这一现象,本文对一种脉冲式与相位式相结合的激光测距系统进行了研究。本文概述了激光测距技术的国内外研究现状,并对四种常用的激光测距技术进行了介绍。提出了一种将脉冲式测量法与相位式测量法相结合的具体方法。拟定出激光测距系统的总体设计方案,将系统分为信号发生、信号接收、混频和鉴相四个模块,完成各模块的电路原理图设计与软件实现。其中,信号发生模块能分别产生15 MHz脉冲信号和14.99 MHz本振正弦信号；信号接收模块能实现将15 MHz光波信号转换为电脉冲信号；混频模块的功能为将初始脉冲信号和回波脉冲信号分别与本振信号作差频处理,得到两路10 KHz余弦信号；鉴相模块最终完成对两路信号的采集与处理,并通过LCD显示测量结果。对信号发生模块的考尔滤波电路、信号接收模块的反向高压发生电路与电压比较滤波电路、混频模块的低通滤波电路和鉴相模块的CIC滤波电路进行模拟仿真分析。分析结果表明,考尔滤波电路对于DDS输出的信号噪声有很好的滤除效果；反向高压发生电路的NE555时钟芯片能输出占空比为87.5%的10.3 KHz脉冲信号,电路可输出149.02 V稳定直流高压；混频模块的低通滤波电路可得到10 KHz目标信号；鉴相模块的CIC滤波电路对乘法器输出的倍频信号具有很好的滤除效果。对高压发生电路进行了实验研究,设计并完成将信号发生模块直接与鉴相模块相连的测试实验。实验结果表明,高压发生电路输出直流电压能达到145 V。测试实验电路引入的系统测量误差最大约0.94 mm。对系统误差进行分析,得到在高压发生电路使用电磁屏蔽罩,在接收模块电路追加设计一个相位补偿电路的改进方法。
[Abstract]:Because laser has the advantages of high brightness, good monochromatic, good directivity and good coherence, laser ranging technology has not only become an important technology in space exploration, but also has been popularized in the fields of geodetic survey, vibration detection, liquid level measurement and so on.At present, there are two kinds of laser rangefinders at home and abroad: phase type and pulse type.The phase laser rangefinder is only used in the close-range measurement where the precision requirement is high, and the pulse laser rangefinder is only used in the remote measurement field where the precision requirement is low.Aiming at this phenomenon, a laser ranging system combining pulse and phase is studied in this paper.In this paper, the research status of laser ranging technology at home and abroad is summarized, and four commonly used laser ranging techniques are introduced.A method of combining pulse measurement with phase measurement is proposed.The overall design scheme of laser ranging system is worked out. The system is divided into four modules: signal generation, signal receiving, frequency mixing and phase detection. The circuit schematic design and software implementation of each module are completed.The signal generation module can generate 15 MHz pulse signal and 14.99 MHz local oscillator sinusoidal signal respectively, and the signal receiving module can convert 15 MHz light wave signal into electric pulse signal.The function of the mixing module is to separate the initial pulse signal and the echo pulse signal from the local oscillator signal to obtain two 10 KHz cosine signals, and the phase discrimination module finally completes the acquisition and processing of the two signals, and displays the measurement results by LCD.The paper simulates and analyzes the Kaul filter circuit of the signal generation module, the reverse high voltage generation circuit and the voltage comparison filter circuit of the signal receiving module, the low pass filter circuit of the mixing module and the CIC filter circuit of the phase discriminating module.The analysis results show that the Kauer filter circuit has a good filtering effect on the noise of the DDS output signal, the NE555 clock chip of the reverse high voltage generating circuit can output 10.3 KHz pulse signal with duty cycle ratio of 87.5%, and the circuit can output 149.02 V stable DC high voltage.The low pass filter circuit of mixing module can get 10 KHz target signal, and the CIC filter circuit of phase detection module has good filtering effect on the frequency doubling signal output by multiplier.The high voltage generating circuit is studied experimentally, and the test experiment of connecting signal generation module directly with phase detection module is designed and completed.The experimental results show that the output DC voltage of the circuit can reach 145 V.The maximum measurement error of the system introduced by the experimental circuit is about 0.94 mm.By analyzing the system error, an improved method of using electromagnetic shield in high-voltage generating circuit and designing a phase compensation circuit in receiving module circuit is obtained.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN249

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