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基于ARM的时差法超声波流量计设计

Design of Time Difference Ultrasonic Flowmeter Based on ARM

作者: 专业:电路与系统 导师:李明伟 年度:2010 学位:硕士  院校: 大连理工大学

Keywords

Time Difference, Ultrasonic Flowmeter, ARM, Man-machine Interface

        随着科学技术的不断发展,对流量测量的精度要求越来越高,高精度的测量显得日益重要。近年来,超声波流量计以其便携式、非接触测量、高精度、智能化的优点,在流量测量中得到了广泛的应用。本文详细介绍国内外超声波流量计发展的现状与特点、流量测量的特点和管道流量分布规律,提出了基于ARM的时差法超声波流量计的设计方法。该方法以时差法测量原理为依据,在硬件电路设计上,选用高性价比、低功耗的微处理器S3C2440A芯片为核心控制系统,负责信号控制、算法处理、数据通信等功能,利用CPLD芯片ISP1253的在线可编程的特性完成了超声波脉冲的发送与接收、波形信号的提取以及开窗信号的控制,选用时间测量芯片TDC-GP2实现了时差的高精度测量,通过设计信号放大电路、滤波电路、自动增益电路,提高了硬件抗干扰能力,从而在硬件上提高了流量计的测量精度。在软件设计上,本文详细介绍了基于ARM体系结构的移植方法和步骤,为时差法流量计软件设计搭建了一个嵌入式Linux系统开发环境。按照微处理器具有较高处理速度、支持嵌入式操作系统的特点,改进了数据处理的算法,提出了基于频域滤波的数据处理算法,从软件上提高了时差法流量计测量的精确度、稳定性和线性度。利用QT工具开发的人机交互界面,方便了管道参数的输入和增强了数据显示实时性。另外,数据通信部分的软件设计开发,可将流量计实时采集的数据传输到PC上进行分析与保存,提高了流量计的在线检测液体流速的能力和流量的智能化。现场测试证明,该设计方法提高了测量精度,满足高精度测量的要求,在流量测量方面具有很好的前景。
    The accuracy of flow measurement has become increasingly demanding with the rapid development of science and technology. Therefore, the high-precision measuring is very important for the flow liquid. The ultrasonic flowmeter with the characters such as portable, non-contact measurement, high-precision, intelligent has been widely used in the flow measurement.In this paper, the development situation and characteristics of the domestic and international ultrasonic flowmeter are described in detail and the characteristics of the flow measurement and distribution of pipe-flow are introduced. The design method of the time-difference ultrasonic flowmeter based on ARM is proposed which takes the measurement theory of time-difference as the basis. In the hardware circuit, the microprocessor chip S3C2440A with high cost performance and low power loss is selected as the core of control system which is responsible for the control of signal, algorithm processing, data communications, and other functions. Using the chip CPLD ISP1253 in system programmable completes the ultrasonic pulse of sending and receiving, waveform signal picking and window signal control. While the time-to-digital converter chip TDC-GP2 achieves high precision measurement of time difference. Signal amplification circuit, filter circuit and auto-gain circuit are designed that enhances the anti-interference ability in order to improve the flowmeter measurement accuracy in the hardware.In software design, the paper describes the transplanting methods and steps of the system structure to put up an embedded Linux system development environment for the software design of the time-difference ultrasonic flowmeter. According to the microprocessor with the characteristics such as high processing speed and supporting embedded operating system, a frequency-domain filtering of the data processing algorithm is proposed in order to improve the accuracy, stability and linearity of the flowmeter. In order to input the parameters of pipeline and enhance data display in time man-machine interface is designed using the develop tool QT. In addition, the software design and development of data communication part make data collected in time transmit to PC for analysis and preservation in order to improve the ability of detection and intelligent of the flowmeter.Field test shows that the design method improves the measuring accuracy and meets the requirement of the high measuring accuracy and the flow measurement has good prospects.
        

基于ARM的时差法超声波流量计设计

摘要4-5
Abstract5
1 绪论10-14
    1.1 课题研究的背景及意义10-11
    1.2 超声波流量计的发展现状与特点11-12
    1.3 本课题主要研究内容12-14
2 时差法超声波流量计的测量原理14-21
    2.1 流量计量物理性参数14-15
    2.2 管内流速分布与平均流速15-18
    2.3 时差法超声波流量计的基本原理18-19
    2.4 影响时差法测量的因素及修正方法19-21
        2.4.1 管内流体流速分布问题19-20
        2.4.2 温度对流速的影响20-21
3 超声波流量计的硬件电路设计21-37
    3.1 流量计硬件总体结构设计21-22
    3.2 ARM9系列微处理器S3C2440A22-27
        3.2.1 ARM系列微处理器及其结构特点22-25
        3.2.2 32位RISC微处理器S3C2440A25
        3.2.3 微处理器复位电路和时钟电路25-27
    3.3 流量计收发电路设计27-28
        3.3.1 超声波信号收发电路27-28
    3.4 基于CPLD信号处理与控制电路设计28-29
        3.4.1 时钟信号的设定28-29
        3.4.2 发射与接收脉冲获取29
    3.5 时差测量电路设计29-33
    3.6 串口通信电路设计33-34
    3.7 网络通信电路设计34-36
        3.7.1 DM9000E芯片概述35
        3.7.2 网络接口的硬件电路设计35-36
    3.8 JTAG接口电路设计36-37
4 超声波流量计的软件设计37-55
    4.1 流量计软件系统总体设计37-38
    4.2 基于ARM体系结构的系统移植38-43
        4.2.1 交叉编译环境的建立38-39
        4.2.2 Bootloader引导程序及其移植39-40
        4.2.3 嵌入式Linux内核的特点与移植40-42
        4.2.4 嵌入式Linux文件系统的选择及其移植42-43
    4.3 超声波收发程序设计43-44
    4.4 流量计时差测量程序设计44-46
        4.4.1 S3C2440A的SPI驱动程序设计44-45
        4.4.2 应用程序设计45-46
    4.5 串口通信程序设计46-48
        4.5.1 串口驱动程序设计47
        4.5.2 串口应用程序设计47-48
    4.6 网络通信程序设计48-55
        4.6.1 嵌入式网络通信基础48-50
        4.6.2 网络驱动程序概述50-53
        4.6.4 网络通信程序的设计53-55
5 流量计人机交互界面的设计55-61
    5.1 Linux图形用户界面的介绍55-57
    5.2 人机交互界面设计思路与构架57-59
    5.3 人机交互界面设计的实现59-61
6 系统测试及数据结果处理61-69
    6.1 系统测试61-63
        6.1.1 超声波流量计安装61-62
        6.1.2 超声波流量计的校验与调整62-63
    6.2 流量计数据采集63
    6.3 流量计数据处理63-66
        6.3.1 均值滤波64
        6.3.2 基于频域滤波的数据处理算法64-66
    6.4 系统误差分析66-68
    6.5 改进措施68-69
结论69-70
参考文献70-72
攻读硕士学位期间发表学术论文情况72-73
致谢73-75
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