摘 要

随着社会的飞速发展，人们对大型机械和的需求和起吊货物的重量都在不断增加，也导致了许多安全事故，为了安全和行业规范，必须要在起重机上加装安全设置。本文主要借助仿真软件proteus，通过压力传感器来间接测量起吊货物的重量，将物理信号转换成了模拟电压信号，通过PCF8591模数转换器将模拟信号转换成数字信号，传送到单片机AT89C51上进行处理并用液晶显示出来，如果超载则进行报警提示。通过仿真设计实现了龙门起重机的超载限制系统，对大型起重机械的安全可靠性具有重要的指导意义。

本文采用将测量绳子的张力改为测量货物底部的压力，从而得出吊装的重量的方法，能够有效减少直接测量钢丝绳张力带来的误差。经过统计得出压力传感器的压强与电压的关系，绘制压强与电压之间关系的拟合曲线，从而精确得出关于压强的二次回归方程，能够有效的减小误差。

关键字：超载限制器、单片机、A/D转换

Abstract

With the rapid development of society, people's demand for large machinery and the weight of lifting goods are increasing, which also leads to many safety accidents. In order to ensure safety and industry standards, it is necessary to install safety settings on the crane. In this paper, with the help of simulation software Proteus, the weight of lifting goods is measured indirectly by pressure sensor, the physical signal is converted into analog voltage signal, and the analog signal is converted into digital signal by pcf8591 analog-to-digital converter, which is transmitted to single chip AT89C51 for processing and displayed by liquid crystal. If it is overloaded, an alarm is given. Through the simulation design, the overload limit system of gantry crane is realized, which has an important guiding significance for the safety and reliability of large lifting machinery.

In this paper, the measurement of the tension of the rope is changed to the measurement of the pressure at the bottom of the goods, so that the method of lifting the weight can effectively reduce the error caused by the direct measurement of the tension of the wire rope. Through statistics, the relationship between pressure and voltage of pressure sensor is obtained, and the fitting curve between pressure and voltage is drawn, so that the quadratic regression equation about pressure can be accurately obtained, which can effectively reduce the error.

Key words :overload limiter, MCU, A / D conversion

目录

第1章 绪论 1

1.1 研究背景 1

1.2 研究的目的和意义 1

1.2.1 研究目的 1

1.2.2 研究意义 1

1.3 国内外现状分析 2

1.3.1 国内现状 2

1.3.2 国外现状 2

第2章 设计超载限制器 3

2.1 需求分析 3

2.2 方案分析 3

2.3 设计原理 3

2.3.1 设计所需器材和元件 3

2.3.2 设计方案 3

2.3.3 系统框图................................................................................................................3

2.3.4 系统流程图 3

第3章 系统设计 5

3.1 概要设计 5

3.1.1 仿真软件的应用 5

3.1.2 单片机封装图及功能 5

3.1.3 1602液晶接口原理图及功能 6

3.1.4 PCF8591原理图及功能 6

3.1.5 MPX4115封装图和功能 7

3.2 详细设计 8

3.2.1 单片机系统模块设计 8

3.2.2 模数转换模块 9

3.2.3 液晶显示模块 10

3.2.4 报警模块 10

3.2.5 压力传感器模块 11

第4章 系统实现 13

4.1 I²C驱动 13

4.1.1 起始信号 13

4.1.2 停止信号 13

4.1.3 数据传输 13

4.2 液晶驱动 14

4.2.1 读状态 14

4.2.2 初始化液晶 14

4.2.3 写数据 14

4.3 模数转换 15

4.3.1 中断和定时器 15

4.3.2获取电压值 16

4.3.3 电压转换 16

4.4 显示及报警 17

第5章 系统测试 17

5.1 显示测试 18

5.2 报警测试 18

第6章 总结 19

参考文献 20

附录A.............................................................................................................................................22

附录B.............................................................................................................................................23