摘 要
随着社会的发展，汽车走了进我们的生活。它的出现给人们的生活带来了很多便利，同时人们也越来越依赖机动车。本文介绍的是一种简易的避障系统，它可以使汽车具有避障功能。避障功能是由超声波发射、接收来实现的，利用超声波测距的原理以实现避障。使换能器向介质发射声脉冲，声波遇到被测物体(目标)后必有反射回来的声波(回波)作用于换能器上。若已知介质的声速为c，第一个回波到达的时刻与发射脉冲时刻的时间差为t，那么即可按式s=ct／2计算换能器与目标之间的距离。在危险距离时进行报警。这样汽车就可以在特定的环境、地点按照人的指示避免相撞。
关键词 超声波；超声波测距；自动停止
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Abstract
With the development of society, cars come into our lives. Its appearance brought a lot of convenience to people's lives, people have become increasingly dependent on the car. This paper presents a summary of the system for obstacle avoidance. It can control car obstacle avoidance function. Ultrasonic obstacle avoidance function is fired by the receiving circuit to the radar. Causes the transducer to the medium launch sound pulse, after the sound wave to meet was measured the object (goal) must have the sound wave which reflects (echo) to affect on the transducer. If the known medium sonic speed is c, the first echo arrives time and the launch pulse time difference is t, then presses between the type s=ct/2 computation transducer and the goal distance. When danger distance carries on reports to the police. This control car can operate in a specific environment, in accordance with the instructions location tasks.
Key words Ultrasonic wave; Ultrasonic ranging; Auto stop
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目 录
摘要 ????????????????????????????Ⅰ Abstract???????????????????????????Ⅱ 第1章绪论 …………………………………………………………………1 1.1 课题背景?????????????????????1 1.2 课题目的及意义 ?????????????????????1 1.3 主要技术指标???????????????????1 1.4 设计功能?????????????????????1 1.5 中外文献综述??????????????????????2 第2章 设计方案选择………………………………………………………3 2.1 设计方案的论证?????????????????????3
2.1.1 测距方式?????????????????????4 2.1.2 超声波发射电路??????????????????4 2.1.3 超声波接收电路??????????????????4 2.1.4 数据显示?????????????????????5 2.2 方案比较 ???????????????????????5
2.2.1 测距方式?????????????????????5 2.2.2 超声波发射电路??????????????????5 2.2.3 超声波接受电路??????????????????6 2.2.4 显示电路?????????????????????6 2.3 电路框图 ???????????????????????6 2.4 本章小结????????????????????????7 第3章 单元电路组成与设计………………………………………………8
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3.1 超声波测距原理?????????????????????8
3.1.1 超声波传感器 ???????????????????8 3.2 单元电路设计 ??????????????????????10 3.2.1 超声波发射电路???????????????????10 3.2.2 超声波接收电路???????????????????11
3.2.3 计数和显示电路???????????????????13
3.2.4 电机控制电路????????????????????14 3.3集成电路结构 ??????????????????????14 3.3.1 555振荡器??????????????????????14 3.3.2 CD4011与非门????????????????????20 3.3.3 CD4069与非门????????????????????21 3.3.4 LM833双运放 ????????????????????21 3.3.5 MC14553计数电路 ??????????????????21 3.3.6 HEF4511译码器 ???????????????????22 3.4本章小结 ????????????????????????23 第4章 整机电路及工作原理 ……………………………………………24 4.1整机原理????????????????????????24 4.2本章小结????????????????????????26 第5章 电路安装调试与误差分析…………………………………………27 5.1电路的组装???????????????????????27 5.2发射与接收电路的调试与测量???????????????27 5.3显示距离的校对?????????????????????27 5.4实验中所遇到的问题???????????????????27
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5.4.1关于短距离测量????????????????????27 5.4.2关于长距离测量????????????????????27 5.5本章小结????????????????????????28 结 论 ………………………………………………………………………29 收获和体会 …………………………………………………………………30 致 谢 ………………………………………………………………………31 参考文献 ……………………………………………………………………32 附录1电路原理图 …………………………………………………………33 附录2主要元器件清单 ……………………………………………………34 附录3参考文献 ……………………………………………………………35 附录4参考文献译文 ………………………………………………………37 附录5系统框图 ……………………………………………………………38
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