基于单片机的金属探测器的设计

摘要

本文着重介绍了一种基于AT89S52单片机控制的智能型金属探测器的硬件组成、软件设计、工作原理及主要功能。该金属探测器以AT89S52单片机为核心，采用线性霍尔元件UGN3503作为传感器，来感应金属涡流效应引起的通电线圈磁场的变化，并将磁场变化转化为电压的变化，单片机测得电压值，并与设定的电压基准值相比较后，决定是否探测到金属。系统软件采用汇编语言编写。在软件设计中，采用了数字滤波技术消除干扰，提高了探测器的抗干扰能力，确保了系统的准确性。此外，文中还对影响金属探测器的灵敏度与稳定性的因素进行了探讨，认为仪器的工作频率、检测线圈的尺寸及匝数等是影响灵敏度的主要因素;而应用现场的环境温度、湿度及线圈的制作工艺和供电电源的稳定程度是仪器稳定性的影响因素。

关键词：单片机，金属探测器，线性霍尔元件，电磁感应，灵敏度

ABSTRCT

This paper describes the composition of hardware and software,working principles and the functions of an intelligent metal detector which mainly consists of AT89S52 Single-Chip Microcomputer and linear Hall-Effect Sensor. The equipment adopts UGN3503U linear hall-effect sensor as probe to detect the magnetic field change of the centre of a search coil resulted from eddy current effect and turn this magnetic field change into voltage change.The Single-Chip Microcomputer measures the peak value of voltage and compares it with reference voltage.Then determine whether detect metel or not.In case of detection of a metallic mass,the Metal Detector porvides an acoustical and optical alarm.The systems software adopts the assmbler language to be written.Inside the software,the digital filter technology is utilized to eliminate the

jamming.So the stability of system and measuring veracity are improved.The effect of all factors on sensitivity and stability of Metel Detetor are discussed in this paper.It is concluded that the operating frequency,the size of the search coil and turns are the main factors effected on the sensitivity of the instrument: the environment temperature and humidity in site,the winding technology of coils and the stability of power supply are the factors effected on stability of instrument.

KEY WORDS: Single-Chip Microcomputer, metal detector, linear hall-effect sensor, electric-magnetic induction, sensitivity

目录

前言 (1)

第1章分析探测金属的理论依据 (3)

1.1理论描述 (3)

1.1.1线圈介质条件的变化 (3)

1.1.2涡流效应 (4)

第2章硬件电路设计 (6)

2.1系统组成 (6)

2.2硬件电路功能描述 (6)

2.2.1线圈振荡电路 (7)

2.2.2数据采集电路 (8)

2.2.3 A/D转换电路 (12)

2.2.4系统控制单元 (15)

2.2.5键盘控制电路 (16)

2.2.6显示报警电路 (17)

2.2.7电源电路 (18)

2.3整机工作原理描述 (19)

第3章系统软件设计 (20)

3.1软件设计思想 (20)

3.2数字滤波及算法说明 (21)

3.3主程序流程图 (21)

3.3.1键盘控制程序设计 (23)

3.3.2数字滤波程序设计 (23)

3.3.3显示与报警程序设计 (25)

第4章主要技术指标分析 (26)

4.1主要技术指标分析 (26)

4.4.1工作频率 (26)

4.4.2灵敏度分析 (26)

4.4.3稳定性分析 (26)

第5章仿真、调试结果及分析 (27)

5.1 仿真、调试目的与内容 (27)

5.2 仿真结果及分析 (27)

5.3 试验总结 (29)

第6章结论 (30)

参考文献 (31)

致谢 (32)

附录1 电路原理图 (33)

附录2 各模块程序清单 (34)