UNIT 20
the role of measurement is to provide information on system status which,in a mechatronic system, is ud to control the operation of the system. this function is performed by the measurement modules which incorporate the necessary nsors and transducers together with any local signal processing. 在机电一体化系统中，测量的角色是提供用于控制系统运行的系统状态信息。这个功能是通过必要的传感器和转换器结合局部信号处理而形成的测量组件来完成的。
measurement technology is not a new science but can be traced back to origins in trade,where the need to quantify,on a basis which was both repeatable and reprentative,the nature of goods on offer led to the introduction of standards for measures such as volume and weight. with the growth in science and technology as exemplified by the renaissance, more and specific measuring instruments evolved to support the growing interest in and investigation of the physical world. 测量技术不是一门新的光科学，他可以追溯到交易的起源，在可重复性和典型性基础上，由于量化的需要，出售
商品的自然特性导致了像体积、重量等测量标准的引入。随着以文艺复兴时期为代表的科技发展，越来越多的专门的测量工具逐步发展以支持我们队物理世界日益增加的关注和研究。
with the advent of the industrial revolution, instrumentation and measurement science began to be applied to manufacturing. the early instruments were analogue in nature and provided information about the basic physical parameters concerned with the operation of the process. 随着工业革命的出现，工具盒测量科学开始应用与制造业。早期的工具是仿自然的，只提供与加工过程有关的物理参数的信息。feedback was achieved by the operator who read the instruments and then made the necessary adjustments to maintain the process within the required bounds. 反馈是通过操作人员读取仪器上的读数，然后做必要的调整，以把工艺过程维持在所要求的范围之内来达到的。
the next step forward came with the introduction of the steam engine and automatic feedback control mechanisms such as the watt governor for speed control. following this lead, instrumentation gradually became more integrated with the process, providing feed
back information to a controller which then regulated the system behavior with minimum of manual intervention. 数字货币是啥向前推进的下一阶段是伴随蒸汽机以及瓦特调速器等自动反馈机械装置的引入到来的。随之而来，仪器产业与过程结合越来越紧密，它提供反馈信息给控制器而使系统操作依赖较少的人工干预。
新年礼物by the late 1960s the advantages of discrete control had been recognized and production process were often controlled by relay bad systems.such relay controllers, though complex in configuration and layout, were relatively unsophisticated and incapable of handling complex information. 到1960三个月亮年代末，离散控制的优势被认知，生产工艺常由继电器系统控制，然而，这种伺服控制在装配和布局上很繁琐，相对不长久且不能出来复杂信息the performance requirements of their associated nsors and transducers were correspondingly restricted to the supply of simple data at a level capable of being utilized by the controllers. 与之相关的传感器和转换器的性能要求也相应被限定在提供能被控制体利用范围内的简单数据。
there conditions were largely maintained with the introduction of computer monitored, as
oppod to controlled, systems in which the computer was ud primarily in a supervisory role as a central machine receiving information quentially from a number of radially connected outstations. with the advent of minicomputers such as the DEC PDP ries, computer controlled systems incread in both number and scope, though they were limited in application by both processing power and cost. 这种状况由于与控制相反的引入较大范围内得以保持，该系统中计算机主要作为中央机承担监管角色，不断从一系列线性相关的外部接收信息。随着DEC，PDP等系列微型计算机的出现，计算机控制系统的数量更大范围更广，尽管由于处理能力和成本等因素使得他们的应用受到限制。 more recently, sophisticated microprocessor systems have resulted in the complex interconnected designs that are now found in both products and manufacturing process. 最近，复杂微处理器以可编程的逻辑控制和分布式嵌入式的微处理机系统激起了错综复杂的内部联系设计，这些在产品和制造工艺中都能实习。
the growth in microelectronics and computing technologies from the mid 1970s that made available low cost processing prower has resulted in a parallel growth in the demand for information about system conditions. 从19世纪开始随着微电子技术和计算机技术的发展，
肥肠面
使低成本操作成为可能，也导致了信息系统状况的平行增长。 in many cas this incread demand could not be met by existing nsors and transducers and resulted in the development of a range of advanced nsors and transducers, often incorporating local processing power, either integral with the nsing element on the same silicon slice or in the form of a single chip microprocessor.在很多场合下，现有传感器和转换器不能满足这种增长需求，而引起了一系列高级传感器和转换器的发展。他们通常配合局部处理能力，可能用于硅片上构成传感器元件或者以单片机形式存在。
nsors, transducers and measurement传感器、转换器和测量
in any measurement system, nsors and transducers are ud to provide information about system conditions. unfortunately, the usage of the terms nsor and transducer is complicated by the variety of different meanings adopted internationally, including in some instances an apparent interchangeability. for the purpo of this book the following definitions are adopted: 在许多测量系统中，传感器和转换器都被用于提供系统状态信息。不幸的是，条件传感器和转换器的使用被国际上五花八门的应用形式复杂化了，包括在一些场合下明显的可互换能力，处于这种目的，本书引入一下概念。
nsors that part of the measurement system that responds to the particular physical parameter to be measured.传感器是测量系统的组成部分乐亭三岛,能对特定的物理参数的测量。
Transducer That component of the system that transfers information in the form of energy from one part of the system to another, including in some cas changing the form of energy containing the information. 转换器 系统的这个组成部分以能量的形式将信息从系统的一部分传递到另一部分，包括在一些情况下改变带有信息的能量的形式
In addition to a nsor/transducer, a measurement may include a pre-processing stage and a post-processing stage, as shown in Fig. 20. 除了传感器、转换器以外，一个测试系统还可能包括前处理单元和后处理单元。如图20.1所示The pre-processing stage rves to characterize the information in the incoming signal before prentation to the nsing element. this then detects and responds to the physical stimulus at its input and provides the input to the transducers. The output signal from the transducer is then operated on by the post-processing stage to produce the final output The relationship between the stages is illustrated by the optical encoder ud for speed measurement shown in Fig. ，
萧和笛的区别前处理单元在它把信息传给传感器之前描述输入信号的信息特征，然后检测并对其输入做出物理模拟响应，将输入信号传送给转换器。从转换器传出的信号被后处理单元处理后生成最终的输出信号。这些单元之间的关系可以通过用于速度测量的光学编码器来描述。红酒用什么能洗掉 20. 2. Here, the light from the sources is pre-procesd by the slotted disc to produce a ries of puls. The light puls received by the transducer which converts the signal into a ries of electrical puls. the post-processing stage then counts the number of puls occurring in a defined time interval to determine the speed of rotation of the shaft carrying the encoder. 如图20.2所示，这里，从光源发出的光被标码的圆盘进行前处理，产生一系列的脉冲，后处理单元通过计算在特定的时间间隔内的脉冲数来确定带有编码器的轴的转速。中心敬老院
