超声波测距系统数字信号处理设计

发布时间：2018-03-28 23:16

本文选题：超声波测距算法　切入点：嵌入式系统　出处：《合肥工业大学》2017年硕士论文

【摘要】：超声波具有指向性强、介质中传播距离远、传播过程中能量消耗缓慢等特点而被作为重要的载体进行信号的传输,同时基于此特性的超声波测距系统由于其对于恶劣天气如雨雪天气、雾霾天气、沙城暴天气等具有高适应性而被广泛应用于军事、工业、汽车制造业等众多领域。目前国内的超声波测距系统在测距精度方面与国外的系统仍有很大差距,因此对于提高精度的数字信号处理方面迫切需要深入研究。本文首先介绍了超声波的特性,并分析了基于超声波载体的测距系统优良的抗干扰性能。以NUC472主控芯片为开发核心介绍了测距系统的硬件框架,结合硬件架构设计了各可编程模块的驱动函数,分析了基于AGC可控增益技术的步进放大算法的设计,并对比分析了非等间隔步进方案的可行性。进行了 FFT匹配算法的设计,用来避免远距离测距噪声误触发带来的步进级数的跳变。介绍了一种适用于超声波回波信号数字通路的技术处理方案,该方案的思路是利用椭圆数字滤波算法作为输入输出端,并结合程序化的包络检测与下采样处理,归结为五步算法,利用MATLAB软件和MDK软件对比开发进行各路算法的设计与仿真,并检验算法开发的合理性。介绍了用于处理五步算法输出的平方律检波算法,此模块作为可选模块,用于提高小信号的动态范围。设计了基于NUC472主控系统的超声波回波匹配算法,目的是避免外界超声波设备的干扰,同时实现测距系统中指定换能器对自身信号的智能识别。设计与仿真了 BCH编解码算法实现方案,构建发送端码元序列的结构与软件调制方式,详细分析了单阈值系统的阈值设定方法,并以此进行软件阈值回归序列的设计。通过板级实验测试了匹配算法的可行性。
[Abstract]:Ultrasonic wave is used as an important carrier for signal transmission because of its strong directivity, long propagation distance in the medium and slow energy consumption in the process of transmission. At the same time, the ultrasonic ranging system based on this characteristic is widely used in military and industry because of its high adaptability to severe weather such as rain and snow weather, haze weather, sandstorm weather, etc. In many fields, such as the automobile manufacturing industry, there is still a big gap between the domestic ultrasonic ranging system and the foreign systems in ranging accuracy. Therefore, there is an urgent need for in-depth research on digital signal processing to improve accuracy. This paper first introduces the characteristics of ultrasonic wave. The excellent anti-interference performance of the ranging system based on ultrasonic carrier is analyzed. The hardware frame of the ranging system is introduced based on the NUC472 main control chip, and the driving function of each programmable module is designed with the hardware architecture. The design of step amplification algorithm based on AGC controllable gain technology is analyzed, and the feasibility of non-equal-interval step scheme is compared and analyzed. The design of FFT matching algorithm is carried out. In order to avoid the jump of step series caused by the noise mistrigger in long distance ranging, this paper introduces a technical processing scheme for ultrasonic echo signal digital path. The idea of this scheme is to use elliptical digital filter algorithm as input and output terminal. Combined with programmed envelope detection and down-sampling processing, it can be summed up as a five-step algorithm, and the design and simulation of each algorithm are carried out by using the contrast development of MATLAB software and MDK software. The square law detection algorithm used to deal with the output of the five-step algorithm is introduced. This module is an optional module. To improve the dynamic range of small signal, an ultrasonic echo matching algorithm based on NUC472 master control system is designed to avoid the interference of external ultrasonic equipment. At the same time, it realizes the intelligent recognition of the signal of the designated transducer in the ranging system, designs and simulates the scheme of BCH codec algorithm, and constructs the structure of the code sequence and the modulation mode of the software. The threshold setting method of single threshold system is analyzed in detail, and the software threshold regression sequence is designed. The feasibility of matching algorithm is tested by board level experiment.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB559

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