毕业设计：基于单片机的超声测距设计系统.doc

中文摘要 本论文比较详细介绍了一种基于单片机的超声测距设计系统，可以用于智能停车场作为车位是否有车的传感器。该系统是以空气中超声波的传播速度为确定条件，利用发射超声波与反射回波时间差来测量待测距离。本系统的安装和使用较方便，价格便宜，并可与无线测控系统配合使用，有非常广阔的应用前景。 本文的超声波测距仪主要是依据智能停车场来设计，但也可以稍加改动用于其他用途。超声测距仪的设计原理是以得到更好的系统性能为目的的。为达到不同的测距范围，单片机可以根据软件来设置远近两种发射模式，即近距离测量时使用8个脉冲串，远距离测量时使用32个脉冲串来增强回波信号，根据回波信号特点来得到了最佳接收机的组成。 论文简单讲述了超声波检测的发展和原理，介绍超声传感器的工作原理及特性，并对于影响测距系统的一些主要参数进行了说明。在介绍超声测距系统功能的基础上，提出了系统的总体构成。针对测距系统发射、接收、检测、显示部分的总体设计方案进行了论证。介绍了AT89S51单片机在系统中的应用，分析了系统各部分的硬件及软件实现。 最后测距仪进行验证。各主要技术指标均达到设计要求。该测距仪对室内停车场有限范围的距离测量具有较高的精度和可靠性，最后文中分析了误差产生的原因及如何对系统进行完善提出了一些改进建议。 关键词:超声波;智能停车;超声传感器;超声测距;单片机ABSTRACT The thesis introduces a kind of ultrasonic distance meter System in detail based on microcontroller.It can be used as smart car parking sensors. The system could measure certain distance with the time between transmit wave and reflected wave on condition in which the speed of transmitting wave is fixed.It is easy to be installed and applied,low in price and capable of being used in combination with telemetering telecontrol system and has extensive application prospects. This ultrasonic range finder in the article is mainly designed based on the smart parking, but it may also be modified for other purposes.The scheme of each part is designed to acquire better performance of the ultrasonic range finder. In order to meet the different distance range,it arranges two transmitting modes in accordence with software in mieroeontroller:high gain reflceted wave to far mode with thirty two Pulses, while low gain reflceted wave to near mode with eight pulses.We get optimum receiver that is based on the characters of the receiving waves. This paper summarizes the development and foundational principle of ultrasonic detection. Then it presents the working mechanization and charaeters of ultrasonic sensor. At the same time, it discusses a number of main technical parameters.Moreover, it proposes the whole structure of the system by introducing the function of ultrasonic distance meter.And then the transmission,