单片机在工业控制中的应用分析（内含中英文，7000汉字）

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单片机在工业控制中的应用分析

当前微处理器化系统与上述的常规方法不同，它将处理、存储和传送三个功能分离形成不同的系统单元。这种形成三个主要单元的分离方法是冯·诺依曼在20世纪40年代所设想出来的，并且是针对微计算机的设想。从此几乎所有制成的计算机都是用这种结构设计的，尽管包含宽广的物理形式，从根本上来说它们均是具有相同的基本设计。

在微处理器化系统中，处理是由微处理器本身完成的。存储是利用存储器电路，而进入和出自系统的信息传输则是利用特定的输入/输出（I/O）电路。要在一个微处理器化时钟中找出执行计数功能的余割特殊硬件是不可能的，因为时间存储在存储器中，而在固定的时间间隔下由微处理器控制增值。但是，规定系统运转过程的软件包含实现计数器功能的单元。由于系统几乎完全由软件所定义，所以对微处理器结构和其辅助电路这种看起来非常抽象的处理方法使其在应用时非常灵活。这种设计过程主要是软件工程，而且在生产软件时，就会遇到产生于常规工程中相似的构造和维护问题。

微型计算机系统由微处理器控制，它管理自己与存储器和输入/输出单元的信息传输。外部的连接与工程系统的其余部分（即非计算机部分）有关。

尽管只有一个存储单元，实际中有RAM和ROM两种不同的存储器被使用。由于概念上的计算机存储器更像一个公文柜，上述的“存储器”一词是非常不恰当的；信息存放在一系列已标号的“箱子”中，而且可按问题由“箱子”的序列号进行信息的参考定位。

微计算机常使用RAM（随机存取存储器），在RAM中数据可被写入，并且在需要时可被再次读出。这种数据能以任一所希望的次序从存储器中读出，不必按写入时的相同次序，所以有―随机‖存取存储器。另一类型ROM（只读存储器）用来保持不受微处理器影响的固定的信息标本；这些标本在电源切断后不会丢失，并通常用来保存规定微处理器化系统运转过程的程序。ROM可像RAM一样被读取，但与RAM不一样的是不能用来存储可变的信息。有些ROM在制造时将其数据标本放入，而另外的则可通过特殊的设备由用户编程，所以称为可编程ROM。被广泛使用的可编程ROM可利用特殊紫外线灯擦除。并被称为EPROM，即可擦除可编程只读存储器的缩写。另有新类型的器件不必用紫外线灯而用电擦除，所以称为电可擦除可编程只读存储器EEPROM。

微处理器在程序控制下处理数据，并控制流向和来自存储器和输入/输出装置的信息流。有些输入/输出装置是通用型的，而另外一些则是设计来控制如磁盘驱动器的特殊硬件，

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或控制传给其他计算机的信息传输。大多数类型的I/O装置在某种程度下可编程，允许不同形式的操作，而有些则包含特殊用途微处理器的I/O装置不用主微处理器的直接干预，就可实施非常复杂的操作。

假如应用中不需要太多的程序和数据存储量，微处理器、存储器和输入/输出可全被包含在同一集成电路中。这通常是低成本应用情况，例如用于微波炉和自动洗衣机的控制器。当商品被大量地生产时，这种单一芯片的使用就可节省相当大的成本。当技术进一步发展，更强更强的处理器和更大更大数量的存储器被包含形成单片微型计算机，结果使最终产品的装配成本得以节省。但是在可预见的将来，当需要大量的存储器或输入/输出时，还是有必要继续将许多集成电路相互连结起来，形成微计算机。

微计算机的另一主要工程应用是在过程控制中。这时，由于装置是按特定的应用情况由微机编程实现的，对用户来说微计算机的存在通常就更加明显。在过程控制应用中，由于这种设备以较少的数量生产，将整个系统安装在单个芯片上所获取的利益常比不上所涉及的高设计成本。而且，过程控制器通常更为复杂，所以要将它们做成单独的集成电路就更为困难。可采用两种处理，将控制器做成一种通用的微计算机，正像较强版本的业余计算机那样；或者做成“包裹”式系统，按照电磁继电器那样的较老式技术进行设计，来取代控制器。对前一种情况，系统可以用常规的编程语言来编程，正如以后要介绍的语言那样；而另一种情况，可采用特殊用途的语言，例如那种使控制器功能按照继电器相互联接的方法进行描述。两种情况下，程序均能存于RAM，这让程序能按应用情况变化时进行相应的变化，但是这使得总系统易受掉电影响而工作不正常，除非使用电池保证供电连续性。另一种选择是将程序存在ROM中，这样它们就变成电子“硬件”的一部分并常被称为“固件”。

尽管大规模集成电路的应用使小型和微型计算机的差别变得―模糊‖，更复杂的过程控制器需要小型计算机实现它们的过程。各种类型的产品和过程控制器代表了当今微计算机应用的广泛性，而具体的结构取决于对―产品‖一词的解释。实际上，计算机的所有工程和科学上的应用都能指定来进行这些种类中的某一或某些工作。

AT89C51是一种带4K字节闪烁可编程可擦除只读存储器的低电压，高性能CMOS8位微处理器，俗称单片机。该器件采用ATMEL高密度非易失存储器制造技术制造，与工业标准的MCS-51指令集和输出管脚相兼容。由于将多功能8位CPU和闪烁存储器组合在单个芯片中，ATMEL的AT89C51是一种高效微控制器，为很多嵌入式控制系统提供了一种灵活性高且价廉的方案。

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Intel公司的MCS-51系列单片机应用的早，影响很大，已成为事实上的工业标准。后来很多芯片厂商以各种方式与Intel公司合作，也推出了同类型的单片机，如同一种单片机的多个版本一样，虽都在不断的改变制造工艺，但内核却一样，也就是说这类单片机指令系统完全兼容，绝大多数管脚也兼容； 在使用上基本可以直接互换。但是，在众多的51系列单片机中，要算ATMEL公司的AT89C51更为实用，因为它不但和8031指令、管脚完全兼容，而且其片内的4K程序存储器是FLASH工艺的，这种工艺的存储器用户可以用电的方式瞬间擦除、改写，一般专为ATMEL、AT89C51x做的可编程器均带有这些功能。显而易见，这种单片机对开发设备的要求很低，开发时间也大大缩短。写入单片机内的程序还可以进行加密，这又很好地保护了开发者的劳动成果。再都，AT89C51目前的售价较低，市场供应也很充足。这就为我们开发本系统提供了很大的方便。

微计算机常使用RAM(随机存取存储器)，在RAM中数据可被写入，并且在需要时可再次读出。这种数据能以任一所希望的次序从存储器中读出，不必按写入时的相同次序，所以有“随机”存储器。另一类型ROM(只读存储器)用来保持不受微处理器影响的固定信息标本；这些标本在电源切断后不会丢失，并通常用来保存规定微处理器化系统运转过程的程序。ROM可像RAM一样被读取，但与RAM不一样的是不能用来存储可变的信息。有些ROM在制造时将其数据标本放入，而另外的则可通过特殊的设备由用户编程，所以称为可编程ROM。被广泛使用的可编程ROM可利用特殊的紫外线灯擦除，并称EPROM，即可擦除可编程只读存储器的缩写。另有新类型的器件不必用紫外线灯而用电擦除，所以称为电可擦除可编程只读存储器EEPROM。

微处理器在程序控制下处理数据，并控制流向和来自存储器和输入/输出装置的信息流。有些输入/输出装置是通用型的，而另外一些则是设计来自控制，如磁盘驱动器的特殊硬件，或控制传给其他计算机的信息传输。大多数类型的I/O装置在某种程度下可编程，允许不同形式的操作，而有些则包含特殊用途微处理器的I/O装置不用主微处理器的直接干预，就可以实施非常复杂的操作。

假如应用中不需要太多的程序和数据存储量，微处理器、存储器和输入/输出可全被包含在同一集成电路中。这通常是降低成本应用的情况，例如用于微波炉和自动洗衣机的控制器。当商品被大量地生产时，这种单一芯片的使用就可节省相当大的成本。当技术进一步发展，更强的处理器和更大的数量的存储器被包含形成单片微型计算机，结果使最终产品的装配成本得以节省。但是在可预见的将来，当需要在量的存储器或输入/输出时，还是有必要继续将许多集成电路相互联接起来，形成微计算机。

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微计算机的另一主要工程应用是在过程控制中。这时，由于装置是按特定的应用情况由微机编程实现的，对用户来主微计算机的存在通常就更加明显。在过程控制应用中，由于这种设备以较少的数量生产，将整个系统安装在单个芯片上所获取的利益常比不上所涉及的高设计成本。而且，过程控制通常更为复杂，所以要将它们做成单独的集成电路就更为困难。可采用两种处理，将控制器做成一种通用的微型计算机，正像较强版本的业余设计计算机那样；或者做成“包裹”式系统，按照象电磁继电器那样的较老式的技术进行设计，来取代控制器。对前一种情况，系统可以用常规的编程语言来编程，正如以后要介绍的语言那样；而另一种情况，可采用特殊用途的语言，例如那种使控制器功能按照继电器相互连接的方法进行描述。这两种情况下，程序均能存于RAM，这让程序能按应用情况变化时进行相应的变化，但是这使得总系统易受掉电影响而工作不正常，除非使 用电池保证供电边连续性。另一种选择是将程序存在ROM中，这样它们就变成电子“硬件”的一部分并常被称为“固件”。尽管大规模集成电路的应用使小型和微型计算机的差别变的模糊，更复杂的过程控制器需要小型计算机实现它们的过程。各种类型的产品和过程控制器代表了当今微型计算机应用的广泛性，而具体的结构取决于对“产品”一词的解释。实际上，计算机的所有工程和科学上的应用都能指定来进行这些种类中的某一或某些工作。正如我们提到的，软件是程序的另一个名字。程序是告诉计算机如何处理数据，使之成为你所需的格式。大多数情况下，“软件”和“程序”这两个词是可相互交换的。

软件具有两大类型。应用软件可以是拥护定制的，或者是封装形式的，进行“终端拥护”的工作。系统软件则完成“后台”工作。你可以认为应用软件是你所使用的软件类型，而认为系统软件是计算机使用的类型。

引用软件：应用软件执行通用的工作，如文字处理和成本估算等，这类软件可以是软件包形式，或者由用户定制的。软件是由专业的编程员预先编写和程序，并且往往装在软盘上出售。现在仅供微机使用的，就有超过12000种应用软件包。

用户制作的软件或称为用户程序，以前的软件均是这一类。20年前，某些组织雇佣程序员创建他们的使用软件。程序员按照要求编写程序，指导公司的计算机去完成任一组织所需的任务。用户程序可以计算工资单，记录仓库中货物情况，计算销售佣金，或者完成类似的企业所需的工作。

系统软件使应用软件作用于计算机。它是后台软件，包括那些帮助计算机管理其内部资源的程序。最重要的系统软件是操作系统，它相互作用于应用软件和计算机之间，操作系统处理下列任务：运行程序，存储数据和程序，并且处理数据。系统程序使使用者从操

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作计算机的复杂工作是解脱出来，集中精力去解决具体问题。最常用的微机操作系统包括DOS等。

模—数传感器

如上所述，在模拟传感器、信号调节，模-数转换器等方面已经积累了大量的经验，所以多数的现在系统趋向于使用这些技术是很自然的。然而，现在有一些本质上就是数字式的测量技术，当用于单独的测量仪表时，还需要某种配套的数字电路，如频率计数器和记时电路，以提供相同数量的设备，因为由整个数字电路完成的大量处理可以由计算机编程完成。

柯林斯(Collins)把控制系统和仪表系统中处理的信号分类如下：

1）模拟系统、系统中的被测参数虽然最初是由传感器以模拟形式给出的，但是要转换成电压或信号，通常还要引入某种求平均值措施，这种措施或者是有意设计的或者是系统固有的。

2）数字编码系统，对所产生的并行数字信号的每位按照某个预先规定的数进行基数加权。本设计中，它们叫做数字式传感器。

3）数字系统就是把某个函(发重复信号的平均速率)，作为被测参数的量度，实现这种功能的设备叫做频率传感器。

某种模拟传感器特别适合于用专门技术对数字输出的转换，其中最通用的是同步器已产生载频调制输出的类似装置。对于普通的模拟用途，这种输出必须解调，以提供一个其大小和符号能代表传感器运动元件位移的直流信号。虽然可以用一般的模-数转换动手术产生数字输出，但也还有这样一些技术，即它们能使同步器的输出，同时具有高精度和高分辨力，其转换速度也比用数-模转换器可能达到的更要快些。

直接数字式传感器实际上是极少的，因为似乎不存在某些可检测特性会随着压力或温度等的变化而作不连续变化的任何自然现象。在普通的仪表系统中，即使在整个设备中不用计算机，使用直接数字式传感器也有许多何必点。这些优点是：

a 易产生处理和存储数字信号，如使用穿孔纸带、磁带； b 电平数字信号对于外部干扰的能力较强； c 满足测量精度和分辨力的需要；

d 人类工程方面的优点是简化数据表示方法（例如数字读出能避免在读标尺或曲线图时出现判断误差）；

e 模拟或混合系统相比，便于维修，备件方便。

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在直接数字式传感器方面最快的转轴编码器，现以广泛用于机床和飞机系统中。可以获得高分辨北海和精度，而且这些装置还可以与被测装置机械连接，以提供能引起可测机械位移的任何参数的直接数字输出。例如，装置在布尔登式压力计的输出轴上的转轴编码可以用来直接测量压力式用蒸汽压力温度计测量温度。这些装置的普遍缺点是仪器和编码的惯性常常限制着响应速度，从而也限制了工作频数。

频率传感器用在只有几个被测变量的联机系统中会起到特殊作用，因为计算机可作为模数转换系统的一部分，而且用它自己的寄存器和时钟对脉冲进行计数或测量脉冲的宽度。在设计这类系统时，必须考虑到存取和处理传感器输出数据所需要的计算机时间。

传感器在可编程程序自动化中的应用

本设计介绍以传感器为媒介的可编程程序自动化在成批生产和离散零部件制造时的材料搬运检查和装配工序上的应用。

可编程自动装置是由计算机控制的多自由度操作机和传感器构成的系统，它可以通过程序完成加工过程中特定工件的加工，并能重新编程序以适应工件的加工，这一点对于产量小而必须频繁变动型号的产品特别重要。目前，工业机器人既没有接触式传感器作为的辅助装置，又没有非接触式传感器作为识别、检查或操作工件的辅助装置。

扩大工业机器人的现有能力需要相当大的增进它对周围环境的感觉与相互配合的能力。尤其是希望以传感器为媒介的、计算机控制的、能模仿人的能力的解释系统。为了满足工业要求，这虚张声势 硬件—软件系统必须能象人一样，甚至比人更好地完成各项工作。特别是它们必须价廉、快速、可靠并能适应工厂环境。

传感器的应用领域大致可分为三个方面：视觉检查、寻找零部件和控制操作。 视觉检查这里，我们只是指视觉检查的一个重要方面：即由人的视觉而不是用测量仪器进行的定性和半定量的检查。对零部件和组装的检查，包括识别零部件，检测有无毛刺、裂纹和空穴，检查外观质量和表面粗糙度，计算孔数和确定其位置及大小，评定组装的完整性等。虽然必须发展一个大型计算机程序库来应付多种类型的检查。寻找工作对于许多工厂的无组织环境中材料搬运和装配工序，也许必须“寻找”工作，既确定工作的地方和方位，有时还需要进行识别。因而必须用视觉传感器来扩大现有机器人的能力，使之能够确定工件的同一性、地点和方位，并执行视觉检查。

控制操作似乎有必要研究一下在操作机控制中如何使用接触式和非接触式这两种传感器，以及评定每种传感器在哪里是最适合的。一种方法是将传感器范围分为粗辨别和细辨别，对粗辨别使用非接触式传感器，对细辨别使用接触式传感器。例如，为了得到一个

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位于随意地点和方位，譬如说，相距十分之一英寸。根据该信息可自动地确定操作机的位置。操作机有点柔性的手指夹住工件，夹紧到足以形成闭合。当检测到达规定的接触压力时，领先接触传感器停止每个手指的动作。在触及工件，但尚未使其移动时，柔曲的手指在停止动作之前折曲了仅仅千分之几英寸。因此，接触传感器完成精确的判定，并已补偿视觉传感器和操作机二者精度的不足。这种很普遍的工作表明了每种传感器方式的相对优点和二者同时使用优点。

另外一些需要使用接触式传感器作精细分辨或精密传感的普通场合是：避免碰撞在操作机的关节处和手爪上使用力传感器。当超过任一预定限定时，运动就立即停止。包装工序把零件整齐地安置在运输箱中。当操作机的柔性手触到箱底、箱侧或相邻零件时，力传感器就可用来使操作机停止动作。这种力反馈方式能补偿运输箱位置和零件位置的变化，也能补偿操作机位置的微小的、但重要的变化。把查塞、轴、螺钉的螺栓插入孔中。力传感器和扭矩传感器能提供反馈信息，以校正由计算机控制的操作机的误差。

通过分析近十年来铁路行车安全现状和已取得的成绩，指出利用科学技术装备是铁路运输生产长治久安的根本大计。我国铁路行车安全保障体系包括两个闭环，一个是移动设备自身监测以及固定设备在线自动检测而组成的集监测、控制为一体的高度信息化的安全监测网络；另一个是人机一体化—环境，以机控为主，人控优先的管理、决策和操纵系统。铁路安全是指在铁路运输过程中，维护铁路政党的运行秩序，保证旅客及铁路员工生命财产安全，保证运输设备和货物完整性的全部生产活动。铁路安全始终是与铁路运输产业自身的发展和生存息息相关的永恒主题，其安全为重点，系统配套发展铁路安全技术与装备，健全行车安全保障也是随着行车速度的提高、行车密度的加大更为人们所重视。在上个世纪和本世纪初，世界上铁路行车速度普遍较低，最高也不超过100km，运输量和行车刻度都不大，由于当时的装备水平很低，事故发生率很高，但是除了列车相撞、爆炸等事故外，其损失并不大。然而，随着列车运行速度的不断提高和行车刻度的逐渐增大，系统中所蕴涵的不安因素就会越来越多，事故造成的直接经济损失和间接损失不会越来越大。现代化铁路的运营模式使人们在对事故的反就速度和承受能力上所产生的心理与胜利负荷都大为加重，必须领先自动或半自动的技术装备来保障铁路行车安全。

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附录B

Single-chip Microcomputer analysis in industrial control applications

Present day microprocessors systems depart from this conventional approach by separating the three functions of processing, storage, and transmission into different sections of the system. This partitioning into three main functions was devised by Von Neumann during the 1940s, and was not conceived especially for microcomputers. Almost every computer ever made is designed with this structure, and despite the enormous range in their physical forms, they have all been of essentially the same basic design.

In a microprocessors system the processing will be performed in the microprocessor itself. The storage will be by means of memory circuits and the communication of information into and out of the system will be by means of special input/output (I/O) circuits. It would be impossible to identify a particular piece of hardware which performed the counting in a microprocessor based click because the time would be stored in the memory and incremented at regular intervals by the microprocessor. However, the software, which defined the system‘s behavior, would contain sections that performed as counters. The apparently together abstract approach to the architecture of the microprocessor and its associated circuits allows it to be very flexible in use, since the system is defined almost entirely in software. The design process is largely one of software engineering, and the similar problems of construction and maintenance, which occur in conventional engineering, are encountered when producing software.

A microcomputer system is controlled by the microprocessor, which supervises the transfer of information between itself and the memory and input/output sections. The external connections relate to the rest (that is the non-computer part) of the engineering system.

Although only one storage section has been shown in the diagram, in practice two distinct types of memory RAM and ROM are used. In each case, the word ? memory ‘ is rather inappropriate since a computer memory is more like a filing cabinet in concept; information is stored in a set or numbered ? boxes ‘ and it is referenced by the serial number of the ? box ‘ in question .

Microcomputers use RAM (Random Access Memory) into which data can be written and from which data can be read again when needed. This data can be read back from the memory in

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any sequence desired, and not necessarily the same order in which it was written, hence the expression ?random ‘ access memory. Another type of ROM (Read Only Memory) is used to hold fixed patterns of information which cannot be affected by the microprocessor; these patterns are not lost when power is removed and are normally used to hold the program which defines the behavior of a microprocessor based system. ROMs can be read like Rams, but unlike Rams they cannot be used to store variable information. Some ROMs have their data patterns put in during manufacture, while others are programmable by the user by means of special equipment and are called programmable ROMs. The widely used programmable ROMs are erasable by means of special ultraviolet lamps and are referred to as EPROM‘s short for Erasable Programmable Read Only Memories. Other new types of device can be erased electrically without the need for ultraviolet light which are called Electrically Erasable Programmable Read Only Memories, EPROM‘s.

The microprocessor processes data under the control of the program, controlling the flow of information to and from memory and input/output devices. Some input/output devices are general-purpose types while others raw designed for controlling special hardware such as disc drives or controlling information transmission to other computers. Most types of I/O devices are programmable to some extent, allowing different modes of operation, while some actually contain special-purpose microprocessors to permit quite complex operations to be carried out without directly involving the main microprocessor.

The microprocessor, memory and input/output circuit may all be contained on the same integrated circuit provided that the application does not require too much program or data storage. This is usually the case in low-cost application such as the controllers used in microwave ovens and automatic washing machines. The use of single package allows considerable cost savings to be made when articles are manufactured in large quantities. As technology develops, more and more powerful processors and larger and larger amounts of memory are being incorporated into single chip microcomputers with resulting saving in assembly costs in the final products. For the foreseeable future, however, it will continue to be necessary to interconnect a number of integrated circuits to make a microcomputer whenever larger amounts of storage or input/output are required.

Another major engineering application of microcomputers is in process control. Here the

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presence of the microcomputer is usually more apparent to the user because provision is normally made for programming the microcomputer for the particular application. In process control applications the benefits of fitting the entire system on to a single chip are usually outweighed by the high design cost involved, because this sort of equipment is produced in smaller quantities. Moreover, process controllers are usually more complicated so that it is more difficult to make them as single integrated circuits. Two approaches are possible; the controller can be implemented as a general-purpose microcomputer rather like a more robust version of a hobby computer, or as a ? packaged ‘ system, designed for replacing controllers based on older technologies such as electromagnetic relays. In the former case the system would probably be programmed in conventional programming languages such as the ones to be introduced later, while in the other case a special-purpose language might be used, for example one that allowed the function of the controller to be described in terms of relay interconnections. In either case programs can be stored in RAM, which allows them to be altered to suit changes in application, but this makes the overall system vulnerable to loss of power unless batteries are used to ensure continuity of supply. Alternatively programs can be stored in ROM, in which case they virtually become part pf the electronic ? hardware ‘ and are often referred to as firmware.

More sophisticated process controllers require minicomputers for their implementation, although the rise of large-scale integrated circuits ? blurs ‘ the distinction between mini-and microcomputers. Products and process controllers of various kinds represent the majority of present-day microcomputer applications, the exact figures depending on one‘s interpretation of the word ?product‘ Virtually sill engineering and scientific uses of microcomputers can be assigned to one or other of these categories.

AT89C51 is a kind take a low-tension for the byte scintillation is programmable can be divided by the read-only memory, ROM(FPERON-Flash Programmable and Erasable Read Only Memory),high performance CMOS8 bit microprocessor, be so called the single chip. The said device adoption ATMEL high definition loses to save not and easily the machine manufacturing technology mints, gathering with commands the machine manufacturing technology mints, gathering with commands MCS-51 of the industrial standard the sum output tube foot adverse to permit concurrently. Because willing be multi-function 8 bit CPUs save with scintillation the machine combine in single a core plate, ATMEL AT89C51 is a kind efficiently microcontroller,

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tendered for a lot of bedding in type regulate system a the scheme between kind flexibility bigher-and low price.

The syndicate of Intel MCS-51 single chip application in series of speedy, affect very big, have become the virtual industrial standard. Subsequence a lot of core plates the factory cooperates with the syndicate of Intel in every kind of way, the single chip that also released the idem genus type, as if a kind single several releases of a machine, although all in the right alone changes fabrication craft, but kernel, and also the single chip command system in scilicet this class full permits concurrently, the overwhelming majority tube foot also permits concurrently ;On the praxis fundamental can direct interchange.

But, in num nervously 51 series single chip, toes calculate the syndicate of ATMEL AT89C51 more practical, because it not only sum 5031commands,take care of the foot full to permit concurrently, but also it‘s a procedure store machine is programming machine that FLASH technical, this kind of technical store machine consumer can in electric way moment erasure, rewrite, generally and just for the ATMEL, AT89Cxx commit all take these functions. Easy to see, the solicit of this kind of single chip folio hair equipment is very low; the tapping time also shortens consumedly. Writing the single a procedure of on line can also steer to encrypt, this protected the fructose industrials of the developer again and nicely. Postscript, current sales price in AT89C51 low, the market supply is too very ample. This develop for us this system tendered the very big amenity.

Microcomputers use RAM (Random Access Memory) into which data can be written and from which data can be read again when needed. This data can be read back from the memory in any sequence desired, and not necessarily the same order in which it was written, hence the expression ?random‘ access memory. Another type of ROM (Read Only Memory) is used to hold fixed patterns are of information which cannot be affected by the microprocessor; these patterns are not lost when power is removed and are normally used to hold the program which defines the behavior of a microprocessor based system. ROMs can be read like Rams, but unlike Rams they cannot be used to store variable information. Some ROMs have their data patterns put in during manufacture, while others are programmable by the user by the means of special equipment and are called programmable ROMs. The widely used programmable ROMs are erasable by means of special ultraviolet lamps and are referred to as EPROM‘s, short for Erasable Programmable

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Read Only Memories. Other new types of device can be erased electrically without the need for ultraviolet light, which are called Electronically Erasable programmable Read Only Memories, EPROM‘s.

The microprocessor processes data under the control of the program,

Controlling the flow of information to and from memory and input/output device. Some input/output devices are general-purpose types while others are designed for controlling special bard ware such as disc drives or controlling information transmission to other computers. Most types of I/O devices are programmable to some extent, allowing difference modes of operation, while some actually contain special-purpose microprocessors to permit quite complex operations to be carried out without directly involving the main microprocessor.

The microprocessor, memory and input/output circuit may all be contained on the same integrated circuit provided that the application does not require too much program or data storage. This is usually the case in low-cost application such as the controllers used in microwave ovens and automatic washing machines. The use of single package allows considerable cost savings to be made when articles are manufactured in large quantities. As technology develops, more and more powerful processors and larger and larger amounts of more are being incorporated into single chip microcomputers with resulting saving in assembly costs in the final products. For the foreseeable future, however, it will continue to be necessary to interconnect a number of integrated circuits to make a microcomputer whenever larger amounts of storage or input/output are required.

Another major engineering application of microcomputers is in process control. Here the presence of the microcomputer is usually more apparent to the user because provision is normally made for programming the microcomputer for the particular application. In process control applications the benefits of fitting the entire system on to a single chip are usually outweighed by the high design cost involved, because this sort of equipment is produced in smaller quantities. More over, process controllers are usually more complicated so that it is more difficult to make them as single integrated circuits .Two approaches are possible; the controller can be implemented as a general-purpose microcomputer rather like a more robust version of a hobby computer, or as a ?packaged‘ system, designed for replacing controllers based on older technologies such as electromagnetic relays. In the former case the system would probably be

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programmed in conventional programming languages such as the ones to be introduced later, while in the other case a special-purpose language maybe be used, for example one which allowed the function of the controller to be described in terms of relay interconnections. In either case programs can be stored in RAM, which allows them to be altered to suit changes in application, but this makes the overall system vulnerable to loss of power unless batteries are used to ensure continuity of supply. Alternatively programs can be stored in ROM, in which case they virtually become part of the electronic ?hardware‘ and are often referred to as firmware.

More sophisticated process controllers require minicomputers for their implementation, although the use of large-scale integrated circuits ?blurs‘ the distinction between mini-and microcomputers. Products and process controllers of various kinds represent the majority of present-day microcomputer applications, the exact figures depending on one‘s interpretation of the word ?product‘. Virtually all-engineering and scientific uses of microcomputers can be assigned to one or other of these categories.

Software, as we mentioned, is another name for programs. Programs are the instructions that tell the computer how to process data into the form you want. In most cases, the word ―software‖ and ―programs ‖are interchangeable.

Software is of two major kinds. Applications software, which may be custom-written or come in packaged form, does ―End-User‖ work. Systems software does ―Background ‖work. You can think of applications software as the kind you use while think of systems software as the kind the computer uses.

Applications software: Applications software performs useful work on general-purpose tasks such as word processing and cost estimating. This kind of software may be packaged or custom-made, Package software is made of programs prewritten by professional programmers that are typically offered for sale on a diskette. There are over 12000 different types of applications packages available for microcomputers alone.

Custom-made software, or custom program, is what all software used to be. Twenty years age, organizations hired computer programmers to create all their software. The programmer custom-wrote programs to instruct the company computer to perform whatever tasks. The organization wanted. Program might compute payroll checks, keep track of goods in the warehouse, calculate sales commissions, or perform similar business needs.

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Systems software: Systems software enables the applications software to interact with the computer. It is ―Background‖ software and includes programs that help the computer manage its own internal resources. The most important systems software is the operating system, which interacts between the applications software and the computer. The operating system handles such details as running programs, storing data and programs, and processing data. Systems software frees users to concentrate on solving problems rather than on the complexities of operating the computer. The most popular microcomputer operating systems include DOS, Windows, Windows NT, OS/2 and UNIX.

As mentioned previously、considerable experience has been accumulated with analog transducers、signal conditioning 、A/D converters etc., and it is natural that the majority of current systems tend to use these techniques. However, there are a number of measuring as separate measuring instruments require some signal digital circuitry, such as frequency counters and timing circuits、to provide an indicator output. This type of transducer, if coupled to a computer、does not necessarily require the same amount if equipment, since much of the processing done the integral circuitry could be programmed and performed by the computer.

Collins classifies the signals handled in control and instrumentation systems as follows: 1) Analog, in which the parameter of the system to be measured although initially derived in an analog form by sensor, is converted to electrical analog, ether by design or inherent in the methods adopted:

2) Ided-digtal, in which a parallel digital signal is generated, each bit radix-weighted according to some predetermined code. These are referred to in this blood as direct digital transducers;

3) Digital, in which a function, such as mean rate of a repetitive signal, is a measure of the parameter being measured. These are subsequently referred to as frequency-domain transducers.

Sine analog transducers are particularly suited to conversion to digital outputs using special techniques. The most popular of the spear cinchers, and similar devices which produce a modulates output of a carried frequency. For ordinary analog use, this output has to be demodulated to provide a be signal whose magnitude and sign represents any displacement of the transducer‘s moving element. Although it is then possible to use a conventional A/D technique to produce digital output can be converted directly to digital output while providing a

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high accuracy and resolution, and at a faster rate than is possible in the A/D converter method.

Direct digital transducers are, in fact, few and far between, since there do not seem to be any natural phenomena in which some detectable characteristic changes in discrete interval as a result of a change of pressure, or change of temperature etc. There are man advantages in using direct digital transducers in ordinary instrumentation systems, even if computers are not used in the complete installation. These advantages are:

A、It is easy to generating, manipulating and storing digital signals, as punched tape, magnetic tape etc.;

B、The need for high measurement accuracy and discrimination;

C、The relative immunity of a high-level digital signal to external disturbance(noise); D、Ergonomic advantages in simplified date presentation (e. g. Digital readout avoided interpretation errors in evading scales or graphs);

E、Logistic advantage concerning maintenance and spares compared with analog or hybrid systems.

The most active development in direct digital transducers has been in shaft encoders, which are used extensively in machine tools and in aircraft systems. High resolution and accuracies can be obtained, and these devices may be mechanically coupled to provide a direct digital output of any parameter which gives rise to a measurable physical displacement. For example, a shaft encode attached to the output shaft of a parameter which gives rise to a measurable physical displacement. For example, a shaft encode attached to the output shaft a Bourdon tube gauge can be used for direct pressure measurement of temperature measurement using vapor pressure the moments. The usual disadvantage of these systems is that the inertia of the instrument and encoder often limits the speed of response and therefore the operating frequencies.

Frequency domain transducers have a special part to play in online systems with only a few variables to be measured, since the computer can act as part of an A/D conversion system and use its own registers as clock for counting pulses or measuring rules computer time required to access and process the transducer output data.

In this paper we are concerned with the application of sensor mediated programmable automation to material -handling, discrete-part manufacturing.

Programmable automation consists of a system of multidegree –of –freedom manipulators

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(commonly known as industrial robots) and performs specified jobs in the manufacturing process and can be applied to mew (but similar) jobs by reprogramming. This is particularly important where production runs are small and where different models may gave to be produced frequently. Today industrial robots gave neither contact sensors as aids to manipulation, nor nonconductor sensors as aids to recognition, inspection, or manipulation of work pieces.

Extending the present capabilities of industrial robots will require a considerable improvement. In their capacity to perceive and interact with the surrounding environment, in particular, it its desirable to develop senor-mediated, computer-controlled interpretive systems that can emulate human capabilities. To be acceptable by industry, these hardware software systems mores perform as well or better than human warders. Specifically, they must be inexpensive, fast, reliable, and suitable for the factory environment.

Sensors needs can be broadly divided into three areas of application: visual inspection, finding parts, and controlling manipulation.

Visual inspection. Here we are concerned only with an important aspect of visual inspection: the qualitative and semi quantitative type of instrument. Such inspection of parts or assemblies includes identifying parts; detecting of burrs, counting the number of holes and determining their locations and sizes; assessing completeness of assembly; and so on .It is evident that a large library of computer progress will gave to be developed to cope with the numerous classes of inspection.

Finding parts. For material handing and assembly operations in the unstructured environment of the great majority of factories, it will probably be necessary to ―find‖ work pieces that is, to determine their positions and orientations and sometimes also to identify them. Thus it is necessary to augment existing robots with unusual sensors to be able to determine the identity, position, and orientation of parts and to perform visual inspection.

Controlling manipulation. It appears useful to consider the use of both contact and nonconductor sensors in manipulator control and try to assess where each sensors in manipulator control and to try to assess where each sensors is most appropriate. One approach is to divide the sensory domain into coarse and fine sensing, using nonconductor sensors for coarse resolution and contact sensors for fine resolution. For example, inaccquiring a work piece that may be randomly positioned and oriented, an unusual sensor may be used to determine the relative

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position and orientation of the work piece rather coarsely, say to one tenth of an inch. From, this information the manipulator can be positioned automatically. The somewhat compliant fingers of the manipulator hand, bracketing the work piece, will now be close enough to defect closure, relying on touch sensors to stop the motion if each finger when a specified contact pressure is detected. After contacting the work piece without moving it, he complains fingers have flexed no more than a few thousandths of an inch before a stopping. The touch sensors have thus performed fine resolution sensing and have compensated for the lack of precision of both the unusual sensor and manipulator. This quite common task illustrates the relative merits of each sensory modality and the advantage of using both.

Packing operations, in which parts are packed in orderly fashion in, tote boxes. Force sensors can be used to uses the bottom of the box, its sides, or neighboring parts. This mode of force feedback compensates for the variability of the positions of the box and the parts and for the small but important variability of the manipulator positioning. Insertions of pegs, shafts, screws and bolts into holes. Force and torque sensors can provide feed back information to correct the error of a computer -controlled manipulator.

Through analyzing railway to drive a vehicle safe current situation and score that has made already the past ten years, point out and scientific technical equipment that railway transportation produce the basics matter of fundamental importance of long-stability. Of our country railways drive a vehicle safe security system including two a piece of ring of closings, each monitor and diagnose and punish, Move the measuring of the regular equipment of the equipment, And regular equipment online to measure regular equipment monitoring in mobile devices but collection that form monitor; Environment rely mainly on the fact that the machine is accused of person more than-machine another one, people accused of have priority manage, make policy and handle the system. The course of railway transportation, maintain railway normal function order safely. Guarantee the life property safety of passengers and railway servant; guarantee all activities in production of transporting equipment and goods integrality. It is a closely linked with industry‘s own development and existence of railway transportation eternal theme throughout that the railway is safe. Its safe level has determined railway transportation competitive power and reputation and economic benefits with other transport ways directly .So railway should have been in order to driving a vehicle safely, in order to ensuing passenger

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transport safely, The related development railway safe practice of the system and equipping, the safe security system that drive a vehicle sound. Safe security systems are developed with the railway to drive a vehicle in the railway, Its importance too improvement, drive a vehicle the increasing of density pays attention to for people in driving speed. Last century and beginning of this century, driving speed of the railway was relatively low generally in the word. Most high to exceed speed per hour No.100 either, freight volume and drive a vehicle big density, because the equipment at that time is very low, but, accident incidence is very high, but except that the train collides, explodes etc. outside the malignant accident. Its loss is not big. However, run speed constant to raise and drive a vehicle density crescent with train. System pregnant to suck safety factor will have been more and more, and indirect losses will have been more and more heavy direct loss that accident cause. Modernized the operational, modes of railways make at reaction speed and ability to bear people in accident and physiology load avatar very psychology produced. Depend on automatic, semi-automatic technical equipment come and ensure railway drive a vehicle safe. Of our country, railways drive a vehicle safe current situation drive a vehicle accident statistical analysis one the past ten years.

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