测控技术与仪器专业英语

定义的测量方法和测量理论

1. Definition of Measurement测量的定义

A possible operational description of the term measurement which agrees with our intuition is the following :“measurement is the acquisition of information ”;the aspect of gathering information is one of the most essential aspects of measurement ;measurement are conducted to learn about the object of measurement ;the measurand .This means that a measurement must be descriptive with regard to that state or that phenomenon in the world around us which we are measuring .一个可能的操作描述这个术语的同意,我们凭直觉测量是下列的“测量信息获取”,采集信息的方面是最重要的方面进行测量,计量了解测量的对象,进行测量。这意味着一个测量必须描述对于这种状态或这一现象在我们周围的世界我们衡量。There must be a relationship between this state or phenomenon and the measurement result .Although the aspect of acquiring information is elementary ,it is merely a necessary and not a sufficient aspect of measurement :when one reads a textbook ,one gathers information ,but one does not perform a measurement.必须有一个关系状态或现象和测量结果信息获取的角度,即使是基础,那只是一个必要的和非充分方面的测量:当一个人阅读教科书,一个收集信息,但是一个人不能进行测量。A second aspect of measurement is that it must be selective .It may only provide information about what we wish to measure (the measurand) and not about any other of the many states or phenomena around us .测量的第二个方面,它必须被选择,只能提供有关我们所希望的那样进行测量测量),而不是对任何其他的许多州或现象在我们身边。This aspect too is a necessary but not sufficient aspect of measurement .Admiring a painting inside an otherwise empty room will provide information about only the painting ,but does not constitute a measurement.这相位也是必须的,但并非任何足够的测量方面.Admiring一幅画在一个否则空房间会提供信息,只有这幅画作,但不构成测量。A third and necessary aspect of measurement is that it must be objective .The outcome of the measurement must be independent of an arbitrary observer .Each observer must extract the same

information from the measurement and must come to the same

conclusion .This, however ,is almost impossible for an observer who uses only his/her senses .Observations made with our senses are highly subjective .Our sense of temperature ,for example , depends strongly on any sensation of hot or cold preceding the measurement .第三个和必要的方面,它必须被测量,结果客观测量必须于任意观测器提取每观察者必须之测相同的信息,必须得出了相同的结论。这,然而,几乎不可能一个观察人士只使用他/她的感官感觉是我们.Observations我们高度主观的感觉,例如,取决于温度有任何感觉热或冷的measuremen前。This is demonstrated by trying to determine the temperature of a jug of water by hand .If the hand is first

dipped in cold water, the water in the jug will feel relatively warm ,whereas if the hand is first dipped in warm water ,the water in the

jug will feel relatively cold. Besides the subjectivity of our observation ,we human observers are also handicapped by the fact that there are many states or phenomena in the real world around us which we cannot observe at all (e.g. magnetic fields) .or only poorly (e.g. extremely low temperatures or high-speed movement) .In order to guarantee objectivity of a measurement we must therefore use artefacts (tools or instruments).这是证明了在调查里面的水的温度用手,如果手先用冷水浸泡到瓶子里的水会感到相对的温暖,而若手第一蘸温水、水到瓶子里会感觉比较冷。除了我们观察的主体性,我们人类的观察家们也不识字而事实有许多州或者现象在现实世界中,我们不能遵守我们周围磁场(如只poorl支)。The task of these instruments is to convert the state or phenomenon under observation into a different state or phenomenon that cannot be misinterpreted by an observer .In other words, the instrument converts the initial observation into a representation that all observers can observe and will agree on .这些仪器的任务是把国家或现象观察进入一种不同的国家或现象,不能被误解被

观察者。换句话说,仪器将最初的观察到任何观测者都表示会同意能封锁。For the measurement instrument’s output ,therefore ,objectively observable output such as numbers on an alpha-numerical display should be used rather than subjective assessment of such things as colour ,etc.. Designing such instruments ,which are referred to as measurement systems ,is the field of (measurement) instrumentation.用来测量仪器的输出,因此,客观观察的输出如数字显示alpha-numerical应使用而不是主观评价诸如色彩,等。设计这样的仪器都被称为量测系统,域(计量仪表。In the following ,we will define measurement as the acquisition of information in the form of measurement

results ,concerning characteristics ,states or phenomena (the measurand )of the world that surrounds us, observed with the aid of measurement systems (instruments ).The measurement system in this context must guarantee the required descriptiveness ,the selectivity and the objectivity of the measurement .在下面,我们将定义测量信息获取的测量结果不确定度的形式,对特征、国家或现象(世界上进行测量在我们周遭,观察与援助的测量系统(仪器测量系统,在此背景下,必须保证所需的descriptiveness,

选择性和客观性的测量。We can distinguish two types of

information :information on the state ,structure or nature of a certain characteristic ,so-called structural information ,and information on the magnitude, amplitude or intensity of a certain characteristic ,so-called metric information .The acquisition of structural information is called a qualitative measurement ,the acquisition of metric information is called a quantitative measurement .If the nature of the characteristic to be measured is not (yet) known ,it must be determined first by means of a qualitative measurement .This can then be followed by a quantitative measurement of the magnitude of the respective characteristic.我们能区分出两种类型的信息:信息对国家、结构或自然的一个特定的特点,所谓的结构信息、信息在大小、振幅或强度一定的特点,所谓的度量信息,获得结构信息被称为定性测量、获取信息度量称为定量测量。如果性质测量特点,还不知道的,它必

须实现

2 Measurement Theory

In the previous section we have seen that measurements from the essential link between the empirical world and our theoretical ,abstract image of the world .This concept forms the basis of a theory of measurement .In this theory a measurement result is considered to be a representation of the actual empirical quantity .Measurement theory treats measurements as a mapping of elements of a source set belonging to the empirical domain space (see Fig .1.1 ) onto the elements of an image (or outcome ) set which is part of the abstract range (or image ) space .在上一节中我们已经看到,测量来自必要的联系,我们的经验世界理论、抽象形象的世界。这观的基础上测量理论。理论,讨论了测量结果被认为是代表了实际经验数量.Measurement理论对测量数据元素的地图源设置属于实证域空间(见图.1.1的元素上一幅图像(whi)或结果。The quantity to be measured (the measurand ) is an element of the source set .For instance ,in the electrical domain we measure electrical current (source set ) but only within a certain range of magnitude (elements). The result of the measurement process is abstract ;it forms an element of the image set in the abstract range space . 测量的量进行测量)是一种元素的源设置情况,因为在电领域受到我们测量电流)

但只有在一定范围内的大小(原理)。测量过程的结果是抽象的,它形成了一个元素的抽象的图像范围空间。For example, the magnitude of the electrical current to be measured in the above example is (by measurement ) assigned a certain number (element ) out of the set of real numbers (image set ).例如,电流的大小来衡量在上面的例子中(通过测量)分配一定数量(元素)从套真实数字(图像)。In other words ,the elements of the source set are empirical characteristics of States and phenomena of the world around us ; the elements of the image set are symbols of the abstract image set of symbols . The symbols can be numbers (quantitative measurements ) but can also be ,for example ,names (quantitative measurements ).换句话说,元素的来源是实证特点设置状态和我们周围的世界的现象;要素的图像的抽象符号图像集象徵。符号可以是数字(定量测量),还可以为例,定量测量)名字。Restricting the definition of measurement further , measurement theory states that measurement is the mapping of elements from an empirical source set onto elements of an abstract image set according to a particular transformation function . The transformation function consists of the assignment algorithms , results or procedures that define the representation of empirical quantities by abstract symbols .测量的定义进一步、测量理论认为测量测绘的要素,从实证源固定在抽象的图像元素根据特定的转换功能。转换函数由任务的算法,结果或程序确定表示的实证数量由抽象符号。In practice the assignment algorithm , rule or procedure is implemented by the employed measurement system. The measurement system therefore determines the representation . As stated earlier , this representation must be done in a description ,objective and selective way . Thus , the image set must consist of elements (measurement outcomes ) which are abstract symbols with a unique meaning about which , by definition , all observers agree .在实践中,分派算法、规则、程序是由受雇测量系统实施。测量系统因此决定表示。如前所述,这些表示都被做以描述、客观、有选择的。因此,对图像集必须包含的元素(测量结果),有抽象符号具有独特的意义,被定义,所有的观察家们也一致。A measurement must be descriptive .In measurement theory this is described in terms of set theory :the relations that exist between the elements of the source set must be maintained under the transformation in the image set ,for example ,’larger than ’, ‘equal to ’ and ‘smaller than ’.一个测量必须描述了在测量理论从集理论存在的关系成分之间的源设置下必须保持对图像集的转型中,例如,“比”、“等于'和'小于”。The set of relations between the elements of the source set is referred to as the relational system (of the source set ). In the previous section we have seen that measurements from the essential link between the empirical world and our theoretical ,abstract image of the world .This concept forms the basis of a theory of measurement .In this theory a measurement result is considered to be a representation of the actual empirical quantity .Measurement theory treats measurements as a mapping of elements of a source set belonging to the empirical domain space (see Fig .1.1 ) onto the elements of an image (or outcome ) set which is part

of the abstract range (or image ) space .

The quantity to be measured (the measurand ) is an element of the source set .For instance ,in the electrical domain we measure electrical current (source set ) but only within a certain range of magnitude (elements). The result of the measurement process is abstract ;it forms an element of the image set in the abstract range space .

For example, the magnitude of the electrical current to be measured in the above example is (by measurement ) assigned a certain number (element ) out of the set of real numbers (image set ).

In other words ,the elements of the source set are empirical characteristics of States and phenomena of the world around us ; the elements of the image set are symbols of the abstract image set of symbols . The symbols can be numbers (quantitative measurements ) but can also be ,for example ,names (quantitative measurements ).

Restricting the definition of measurement further , measurement theory states that measurement is the mapping of elements from an empirical source set onto elements of an abstract image set according to a particular transformation function . The transformation function consists of the assignment algorithms , results or procedures that define the representation of empirical quantities by abstract symbols .

In practice the assignment algorithm , rule or procedure is implemented by the employed measurement system. The measurement system therefore determines the representation . As stated earlier , this representation must be done in a description ,objective and selective way . Thus , the image set must consist of elements (measurement outcomes ) which are abstract symbols with a unique meaning about which , by definition , all observers agree . A measurement must be descriptive .In measurement theory this is described in terms of set theory :the relations that exist between the elements of the source set must be maintained under the transformation in the image set ,for example ,’larger than ’, ‘equal to ’ and ‘smaller than ’. The set of relations between the elements of the source set is referred to as the relational system (of the source set ).

This empirical relational system determines the structure of the source set . Likewise ,an abstract relational system determines the structure of the image set (for instance ,the set of relational that apply to the set of integer numbers ). A measurement (representation ) is now called descriptive if the relational system or structure of the empirical source set is invariant under the transformation (measurement ) .

The measurement only represents that which is measured if the two relational systems are identical ; otherwise information is lost in the mapping . An example is measuring with a very low resolution ; two different current magnitudes are mapped onto the same outcome , and are indistinguishable from each other .

nal system determines the structure of the source set . Likewise ,an abstract relational system determines the structure of the image set (for instance ,the set of relational that apply to the set of integer numbers ). A measurement (representation ) is now called descriptive if the relational system or structure of the empirical source set is invariant under the transformation (measurement ) . 本实证关系系统确定源的结构。同样地,抽象的关系系统确定图像的结构(例如,关系,适用于整数的数字)。测量(表示)现在称为描述性如果关系系统或结构变化设置经验主义来源转换(下测量)。The measurement only represents that which is measured if the two relational systems are identical ; otherwise information is lost in the mapping . An example is measuring with a very low resolution ; two different current magnitudes are mapped onto the same outcome , and are indistinguishable from each other .测量测量只代表了,如果两个关系系统都是相同的,否则资料遗失在映射。一个例子是测量一个非常低分辨率;两个不同电

流大小映射到相同的结果,与对方。

Unit2 Measurement of Physical Quantity物理量测量

The physical quantities listed bellow are often used in test and measurement technology .The first 2 are commonly called as electrical

quantities and the other are commonly called as electrical

parameters .

Usually the sensors receive the information of quantities under measurement (QUM) and convert it into variation of electrical parameters or electrical potential, which will normally be conditioned ,and then converted into the electrical quantities ,specially the current ,and sent to the A/D converters . 如下所示的物理量的常被用于测试和测量技术,第

2通常被称为电子数量和其他通常被称为电气参数。

通常传感器接收信息清单QUM测量(下),把它转化成电气参数的变化或电气潜力,通常会条件,然后转化为电气数量,特别是当前的众长老、就差人到A / D

耐.

Electrical potential difference 电气电位差

The primary standard for electrical potential difference used to be provided by an electrochemical standard cell (the Weston standard cell ).The voltage of a Weston cell is approximately 1.01860 V at 20`C,with an inaccuracy of 3X10^-6 under optimal conditions. Optimal conditions means a variation of temperature less than 10^-3 K, no load, no vibrations or jolting . The cell must remain in an upright position. A Weston standard cell has a very long thermal after-effect. After the cell has been heated to 30`C it can take 6 months before it is totally stable within 0.3u V of the original value at 20degrees .Furthermore ,a Weston cell will age , resulting in an increase in the internal resistance (R1~500-1000欧)，and a small decrease of a few uV in the output voltage (during the first years ).电气的基本标准的用于电位差由电化学标准电池的(韦斯顿标准电池电压成),大约1.01860韦斯顿细胞是五世在20'C的精度,在优化的分析条件下,3X10 - ^。最优性条件温度的变化是指小于10 ^ - 3钾、空载,没有振动或震动。细胞必须保持在一个垂直位置。一个韦斯顿标准电池的有很长

的热after-effect。在细胞被加热到3.

Electrical current 电流

lectrical current is standardized by measurement with an instrument called a ‘current balance’. This device measures the electromagnetic force between two current carrying coils (one fixed ,one moving ) by balancing it with the force of gravity ,acting on a known mass . The force between the coils is given by F=I^2dM/dx , in which M is the known mutual induction of the coils and x is the known distance between them . The differential quotient dM/dx is determined by known geometry of the coils .

通过测量规范激励激光器阻抗电流被称为“用铁器当期资产”。这种装置措施电磁力在两个电流负载线圈(一个固定的,一个运动)平衡与重力的作用下,行动在一个已知的质量。线圈间的力进行女=我^ 2dM / dx,,M是已知的相互感应的线

圈与x是已知的间距。鉴别商dM /远程接收由已知的几何学的线圈。

Electrical resistance 电阻

Standards of electrical resistance are resistors wound of special alloy wire giving a minimal temperature effect .An example of such an alloy is evanohm , consisting of 74% nickel ,20%chromium and 6%aluminium and iron . This alloy is frequently used for high resistance standards (10kQ). For low resistance values (1Q) manganine (86%Cu ,12%Mn ,2%Ni ) or constantan (%Cu ,45%Ni ,1%Mn ) is often used .Higher –order resistance standards are kept at very accurately stabilised temperature by thermostats .标准是电阻的特殊合金线电阻伤口给一个最小的温度效应的代表.An evanohm是一种合金,由74%镍、20%chromium和6%aluminium与铁。这种合金是经常用于高阻

标准(10kQ)。低阻值(第manganine(86%Cu,12%Mn),2%Ni)或

constantan(%Cu,45%Ni,1%Mn)常常被.Higher -order电阻标准保持非常准确

稳定温度温控器。 Capacitance 电容

It is possible to construct a capacitor from four coaxial cylinders , whose capacitance only depends on the length of the cylinders . Such a capacitor is particularly suitable as a standard of capacitance , since only the length has to be determined accurately . With the aid of optical interferometry this can be done extremely accurately . These so-called Thompson-Lampard cylinder capacitors can achieve an inaccuracy of less than 10^-8. 它可以构建电容器的从四个同轴钢瓶,电容仅凭长度的汽缸。这样的电容器是特别适合标准的电容,因为只有长度必须提供准确的参数。与援助的光学干涉技术能够依此作成,非常准确。这些所谓的Thompson-Lampard缸电容可以达到不小于10 ^ - 8。 A disadvantage ,however ,is the fact that the capacitance is small (approximately 1.9pF per metre ). For lower-order standards other configurations of electrodes are used ,which provide larger capacitance values (10~1000pF),but also come larger uncertainties .然而,一个不利条件的人来说,这一事实1.9pF电容小(大约每米)。其它结构的标准为查核使用电极,提供较大的电容值(10 ~ 1000pF),但也来了更大的不确定性。

Inductance 电感

Accurate standards of inductance are difficult to realise . This is caused by the many parameters that determine the relatively complex of a coil ,all of which influence the accuracy of the inductor .Furthermore ,power losses

occur ,due to wire resistance ,proximately effects and eddy

currents ,which add to inaccuracy ,Currently a available standards of inductance have an inaccuracy of about 10^-5 .精确的标准的电感难以想象。这是由于很多参数,确定的较为复杂的线圈,影响电感的准确性发生,损增益.再说,由于线电阻、迟延直接影响和涡流、增加到不准确,目前提供标准的电感有一

个不大约10 ^ - 5。 Frequency 频率

The standard of frequency is based on quantum mechanical effect that electrons in an atom can only occupy one of a limited number of energy levels .If an electron jumps to a higher or a lower energy level ,the difference in energy E of the photon that is absorbed or a emitted , respectively ,is related to the frequency of the photon by the expression E=h f0.When atoms are irradiated with electromagnetic energy of frequency f0,many electrons will pass to higher energy levels .标准的频率是基于量子力学效应原子电子之一只能占据数量有限的能量水平,如果一个电子的价格涨到一个更高的或较低的能量水平,不同的能源E被吸收的光,分别或发出有关光子的频率的表情E = h f0 . 当原子电磁能量下的频率f0,许多电子将通过更

高能量水平。

2.easurement of non-physical quantities 测量非物理性的数量 Non-physical quantities found in non-technical fields are very difficult

or even impossible to measure, mainly because they are part of very complex systems (people, organizations ,societies ,etc.) . Cardinal measurements can therefore very rarely be made when dealing with the non-physical characteristics, states or phenomena in such systems.物质中发现数量非技术方面非常困难,甚至是不可能了,主要是因为他们测量非常复杂的系统的一部分(人们、组织、学会等)。因此基本测量很少会处理的非物质的特点、国家或

现象在这种系统中。

When measuring complex systems or objects, the measurand often also depends on all kinds of other quantities .Usually ,the nature and magnitude of these dependencies are unknown .Furthermore, these parasitic quantities ,which influence the measurement result ,are not constant during the measurement, making it impossible to correct any errors in the measurement .This means that the measurement is no longer selective ;other factors are also being measured.在测量复杂系统或者对象,进行测量也经常取决于其他各种数量.Usually、性质及大小并不为人所知.再说,这些依赖这些寄生虫数量,影响了测量结果,在测量过程不是固定不变,让人很难矫正错误的测量。这意味着测量不再是选择性,其他的因素也被测量。 Non-physical quantities are usually a part of a living organism or an organization of living beings .It is essential to the nature of an organism or an organization that they maintain (social , cultural , political) interactions with their environment 物质通常数量的一部分或生物的一个组织,它是必要的生物有机体的性质或组织让他们保持(社会、文化、政治)相互作用与环境。For this reason , it is usually not possible to perform an isolated measurement in the same way we can with inanimate things (putting in a thermostat, hooking up to a fixed supply voltage, etc.).基于这个原因,它通常不可能完成一个孤立的测量同样地我们可以和无生命的东西(放进一个温控器、猎艳以一个固定的电源电压等)。It is , for example, not very practicable to isolate a section of the population from the rest of the world , for the sake of an economic measurement conducted to verify the relationship between the scarcity and the price of consumer goods .The object of the measurement continues to interact with its surroundings, to an extent and in a manner that remains unknown.例如,不太可行的隔离人群的一部分从世界的其他地方,为了进行经济测量,验证的缺乏和之间的关系的消费品的价格,测量对象继续相互作用,它周围的环境中,在某种程度上,而在某种程度上,但仍是未知的。 These interactions obscure and corrupt the measurement results to some unknown degree ,depending on the sensitivity to these interference.这些互动晦涩、的测试结果,一些不为人知的程度,根据这些敏感的干扰。Also ,the repetition of experiment is often not possible when dealing with such complex measurement objects .With physical measurements we often repeat a measurement to see how reproducible it is and to determine the magnitude of random errors .With non-physical measurements ,however ,the object often behaves differently the second time ,because it no longer motivated to co-operate ,has become tired ,etc .Think ,for example ,of taking the same examination twice .同时,重复实验通常是不可能在处理复杂的测量各种物理测量物体我们经常重复测量重复性看到并决定随机误差的大小以非物理性的测量,但对象第二次常常表现出不同,因为它不再有动力去合作,已成为累了,等.Think,例如建立相同的检查两次。For ethical ,political or financial reasons it is also usually not possible to freely modify variables to determine how they influence the measurement object ,for example ,increasing the scarcity of food in an economic community to determine the influence on the consumer’s spending behavior . 为职业道德、政治或经济的原因也通常不可能自由修改变量来确定他们怎样影响测量对象,例如,提高食物的缺乏经济社会确定影响消费者的消费行为。As opposed to a physical measurement ,the object of a non-physical measurement is often conscious of being measured .The mere fact that we measure influences the subject .The subject will behave differently in a laboratory than in daily life . An example for an often used (and abused ) test animal :the rat .A measurement can even cause

irrevocable processes in the object .我们反对一种物理测量、非物质的对象测量被测经常意识到,单单是我们测量的影响,这个问题行为不同学科将在一个实验室比的日常生活中。一种常用的榜样(几乎被滥用)试验鼠动物:测量。甚

至导致不可撤销的过程中.Certain psychological experiments ,for example ,can cause catatonic states in certain patients ,resulting in disorders or even chronic schizophrenia .The effects measurement above will generally make it different to reproduce measurements in the fields of human and social studies accurately ,assuming that these measurements can actually be made reasonably selectively and objectively . 某些心理学实验,例如,会造成的紧张性精神症在某些病人,分别导致疾病甚至慢性精神症患者影响以上,测量不同,通常也使复制测量结果和人类社会的研究领

域准确、假设这些测量了可以有选择地、合理的基础性工作。

3 . The Nature of Data数据的性质

Information you gather is called data. Data can be a factual statement of physical phenomena. For example, the statement ”the copper was removed by the chemical reaction with ferric chloride” is descriptive data. When data is purely descriptive, it is said to be qualitative data. When a quantity is measured, we associate numerical values with it, and the information is more useful in a scientific way because more information is present. Information about the magnitude or intensity of a physical phenomenon is called quantitative data. Recall that the quantity that is being measured is called the measured. Instrumentation extends the human senses by allowing a numerical value or values to be associated with the measurand.你收集的信息被称为数据。数据可以一种事实的陈述的物理现象。例如,声明“铜被化学反应和氯化铁”是描述性的数据。当数据纯粹是描述性的,据说是定性的数据。当一个量测量,我们所说的数值,和信息是比较有用的科学发展,因为更多的信息都出席了。信息或强度大小物理现象。Numerical data can be categorized in several ways. It can be an isolated value or can be dependent on time or location. Values recorded directly from an experiment or observation are called empirical data. Prior to processing, empirical data is often referred to as raw, or unprocessed data, whereas data that has been analyzed is called processed data. Data can also be generated by theoretical calculations. Frequently, theoretical data is compared to measured or processed data as a test of the theoretical model.数字数据可分为几个方面。它可以是孤立的价值或可以依赖于时间和地点。价值观记录,直接从一个实验或观察被称为实证数据。在处理、数据的实证分析常被引用为原料,或未加工的数据,而数据被称为加工的数据进行了分析。所产生的数据也可以理论计算。通常情况下,比较理论数据测或处理过的数据作为测试的理论。After data is collected, it may need to be processed either by applying mathematical computations to it or by arranging it in some meaningful manner. This procedure is called data processing or data reduction. Data may be entered into a computer for reduction, or, In some cases, the measurement instrument may perform the data reduction within the instrument. For example, a digital oscilloscope may present the rms value of a voltage as a displayed numeric value. As part of the process of data reduction, obvious errors or discrepancies should be looked for; sometimes statistical processing is applied to indicate the nature of experimental precision..数据收集后,它可能需可以被处理和利用数学计算通过把一些富有意义的方式。这个过程被称为数据处理和数据的减少。数据可以进入降低计算机,或者,在某些情况下,检测仪表可以进行天文数据归算在仪器。例如,一个数字示波器的均方根值可呈现电压作为显示数值。作为整个过程的一部分,减少,明显的错误发生的数据或矛盾之处,应该找;有时应用统计处理表明自

然实验精度。

Unit6 1. An Overview for Control System在控制系统的概述

Control systems are everywhere around us and within us. *Many complex control systems are included among the functions of

the human body. An elaborate control systems centered in the hypothalamus of the brain maintains body temperature at 37 degrees Celsius (℃) despite changes in physical activity and external ambience.控制系统到处都是我们及在我们。*许多复杂的还包括控制系统的功能的人体。一个精心制作的控制系统集中在下丘脑的大脑维持体温孕37摄氏度(℃)尽管改变身体的活动和外部的气氛。 In one control system—the eye—the diameter of the pupil automatically adjusts to control the amount of light that reaches the retina. Another control system maintains the level of sodium ion concentration in the fluid that surrounds the individual cells.在一个控制系统对学生eye-the直径自动调节控制光的总量达到视网膜上。另一个控制系统保持

水平的钠离子液体浓度包围在单个细胞。

第六章

1. An Overview for Control System

控制系统的概述

• Control systems are everywhere around us and within us.

*Many complex control systems are included among the functions of the human body. An elaborate control systems centered in the hypothalamus of the brain maintains body temperature at 37 degrees Celsius (℃) despite changes in physical activity and external ambience. In one control system—the eye—the diameter of the pupil automatically adjusts to control the amount of light that reaches the retina. Another control system maintains the level of sodium ion concentration in the fluid that surrounds the individual cells.

控制系统到处都是我们及在我们。*许多复杂的还包括控制系统的功能的人体。一个精心制作的控制系统集中在下丘脑的大脑维持体温孕37摄氏度(℃)尽管改变身体的活动和外部的气氛。在一个控制系统对学生eye-the直径自动调节控制光的总量达到视网膜上。另一个控制系统保持水平的钠离子液体浓度包围在单个细胞。Threading a needle and driving an automobile are two ways in which the human body functions as a complex controller. The eyes are sensor that detects the position of the needle and thread, or of the automobile and the center of the road. A complex controller, the brain, compares the two positions and determines which actions must be performed to accomplish the desired result. The body implements the control action by moving the thread or turning the steering wheel; an experienced driver will anticipate all type of disturbances to the system, such as a rough section of pavement or a slow-moving vehicle ahead. It would be very difficult to reproduce in an automatic controller the many judgments that an average person makes daily and unconsciously

穿好针汽车,开的是两种方法人体功能是一个复杂的控制器。眼睛是传感器检测位置的针和线,或汽车和中心的路。一个复杂的控制器,大脑,比较了两个位置并确定哪种行动必须进行达到的结果。实施控制作用的身体可以通过移动的螺纹或把方向盘,一个有经验的车手能够预见到所有类型的干扰的系统,例如粗糙的一段路面或一个缓慢移动车辆前进。将很难复制一个自动控制器的很多判决,平均每日人无意识Control systems regulate temperature in home, school, and buildings of all types. They also affect the production of goods and services by ensuring the purity and uniformity of the food we eat and by maintaining the quality of products from paper mills, steel mills, chemical plants, refineries, other types of manufacturing plants. Control systems help protect our environment by minimizing waste material that must be discarded, thus reducing manufacturing costs and minimizing the waste disposal problem. Sewage and waste treatment also requires the use of automatic control system控制系统调节温度在家里、学校和各种类型的建筑。他们也影响产品和服务的生产,使产品的纯度和保证我们所吃的食物的均匀性维护质量的产品,从造纸厂、钢厂、化工厂、炼油厂以及其他类型的制造工厂。控制系统帮助保护我们的环境,通过最小化必须被丢弃的废弃物的,从而减少生

产成本及减少废物处置问题。污水和垃圾处理也需要使用自动控制系统的无意识A control system is any group of components that maintains a desired result or value. From the previous examples it is clear that a great variety of components may be a part of a single control system, whether they are electronic, mechanical, hydraulic, pneumatic, human, or any combination of these. The desired result is a value of some variable in the system, for example, the direction of an automobile, the temperature of a room, the level of liquid in a tank, or the pressure in a pipe. The variable whose value is controlled is called the controlled variable. 一个控制系统是任何集团的组成部分,期望的结果保持或价值。从以往的例子很明显,各式各样的元件可以部分一个控制系统,无论他们是电子、机械、液压、气动、人类,或者任何这些情况的组合。期望的结果是有价值的一些变量的系统,例如,一辆汽车的方向,室内温度,一级的液体在坦克和压力在一根管子。其价值是控制变量称为控制变量。To achieve control, there must be another variable in the system that can influence the controlled variable. Most systems have several such variables. Control system maintains the desired result by manipulating the value of one of these influential variables. The variable that is manipulated is called the manipulated variable. The steering wheel of an automobile is an example of manipulated variable.

An excellent idea of the scope of control systems is given in an Instrument Society of America film, “Principles of Frequency Response,”1958

以达到控制,必须有另一个变量的系统中,可以影响控制变量。大多数系统有几个这样的变量。控制系统保持期望的结果利用价值之一,这些影响力的变量。操纵的变量称为被操纵的变量。转向汽车轮操纵的例子是可变的。范围的一个很好的想法给出了控制系统的票据上的美国社会电影“原则”的频率响应,1958年Control systems are becoming steadily more important in our society . We depend on them to such an extent that life would be unimaginable without them .

Automatic control has increased the productivity of each worker by releasing skilled operators from routine tasks and by increasing the amount of work done by each worker. Control systems improve the quality and uniformity of manufactured goods and services : many of the products we enjoy would be impossible to produce without automatic controls. Servo systems place tremendous power at our disposal, enabling us to control large equipment such as jet airplanes and ocean ships . 控制系统变得稳定更重要的,在我们的社会。我们依靠他们逗乐了,生活将会不可思议的不带他们。自动控制增加了每个工人的生产力通过释放熟练的操作工人的常规任务和通过增加少量的工作由每个工人。控制系统的不均匀性提高产品质量,制成品和服务:许多产品我们喜欢不可能产生没有自动控制。伺服系统的地方为我们掌握了巨大的力量,使我们控制大型设备如喷气飞机和海洋的船只。Control systems increase efficiency by reducing waste of materials and energy , an increasing advantage as we seek ways to preserve environment . Safety is yet another benefit of automatic control . Finally , control systems such as the household heating system and the automatic transmission provide us with increased comfort and convenience . 控制系统提高效率,以减少浪费材料、能源、越来越的优势,因为我们想办法,保护环境。安全是另一个利益的自动控制。最后,控制系统,如家庭采暖系统和自动传输给我们提供增加舒适和便利。In summary , the benefits of automatic control fall into the following six broad categories ① Increased productivity ② Improve quality and uniformity ③ Increased efficiency : ④ Power assistance :⑤ Safety :⑥ Comfort and convenience . 总之,自动控制的好处落在接下来的六个大类①增加生产率②提高质量和均匀性③提高效率④助力⑤安全⑥舒适和便利。Control systems are classified in a number of different ways . They are classified as closed-loop , depending on whether or not feedback is used . They are classified as analog or digital , depending on the nature of the signals —continuous or discrete . They are divided into

regulator systems and follow-up systems , depending on whether the setpoint is constant or changing. They are grouped into process control systems or machine control systems, depending on the industry they are used in —processing or discrete-part manufacturing . Processing refers to industry they are used to produce products such as food, petroleum, chemicals, and electric power. Discrete-part manufacturing refers to industries that make parts and assemble products such as automobiles, airplanes, appliances, and computers. They are classified as continuous or batch (or discrete) , depending on the flow of product from the process-continuous or intermittent and periodic. Finally, they are classified as centralized or distributed, depending on where the controller are located—in a central control room or near the sensors and actuators. Additional categories include servomechanisms, numerical control, robotics, batch control, sequential control, time-sequential control, time-sequenced control, event-sequenced control, and programmable controllers. These general categories are summarized below. 控制系统进行了分类在很多不同的方式。它们分别为闭环,与否取决于反馈使用。它们分别为模拟或数字,根据信号的性质的连续或离散。他们分成调节器系统和跟踪系统,取决于设定的是常数或改变。他们被分成过程控制系统或机器控制系统,根据产业它们被用于处理或离散的这一部份制造。处理是指工业他们被用来制造产品,如食物、石油、化工、电力。离散的这一部份制造是指企业部分和装配产品,如汽车、飞机、五金电子、家用电器、和电脑。它们分别为连续或批次(或离散,取决于产品的流动过程的连续或间歇性和周期性的。最后,它们分别为集中的还是分散的,取决于那里控制器位于控制室感应器与驱动器或附近。额外的种类包括自控、数控、机器人学、批量控制、时序控制、时间时序控制、时间顺序控制,事件顺序控制,可编程控制器。这些一般的范畴下面被总结。 2.Classification of Control Systems2。控制系统的分类 • (1) feedback(1)反馈

①Not used—open-loop不用开环控制 ②Used—closed-loop用闭环控制

• (2) Type of signal(2)类型的信号 ①Continuous—analog连续模拟 ②Discrete—digital离散数字 • (3) Setpoint(3)设定的

①Seldom changed—regular system很少改变例行系统

②Frequently changed—follow-up system频繁改变追踪系统 • (4) Industry(4)工业

①Processing—process control加工过程控制 • a. Continuous system联系系统 • b. Batch systems成批处理系统

②Discrete-part manufacturing—machine control离散的这一部份加工机控制

• a. Numerical control数字控制

• b. Robotic control systems机器人控制系统 • (5) Location of the controllers(5)位置的控制器

①Central control room—centralized control控制室集中控制

②Near sensors and actuators—distributed control②分布式控制传感器与执行器附近

• (6) Other categories(六)其他类别 ①Servomechanisms

②Sequential control时序控制

• a. Event-sequenced control事件顺序控制 • b. Time-sequenced control时序控制 ③Programmable controllers程序控制器

3.Block Diagrams and Transfer Functions3。框图和转让功能

Although it is not unusual to find several kinds of components in a single control system ,or two systems with completely different kinds of components , any

control system can be described by a set of mathematical equations that define the characteristics of each component. A wide range of control problem-including process, machine tools, servomechanisms, space vehicles, traffic, and even economics--can be analyzed by the same mathematical methods. The important feature of each component is the effect it has on the system. The block diagram is a method of representing a control system that retains only this important

feature of each component. Signal lines indicate the input and output signals of the component. As show in Fig.6.1.

Each component receives an input signal from some part of system and produces an output signal for another part of the system. The

signal can be electric current, voltage, air pressure ,liquid flow rate, liquid pressure, temperature, speed, acceleration, position, direction, or others. The signal paths can be electric wires,

pneumatic tubes, hydraulic lines, mechanical linkages, or anything that transfers a signal from one component to another. The component may use some source of energy to increase the power of the output signal. 尽管它是不寻常的发现几种部件整合进单一控制系统或两种制度完全不同类型的组件,任何控制系统可以被一套数学方程定义各组成部分的特点。广泛的控制问题包括工艺、机床、servomechanisms,太空交通工具、交通,甚至经济学可以分析相同的数学方法。各组成部分的重要特征是影响系统。是一种框图的控制系统会表现的只有这重要的特征保留每个组件。的信号线,注明输入和输出信号的各组成部分。作为展示在Fig.6.1。每个组成部分信号接收到输入信号系统的一部分输出信号,从而产生了另一个系统的一部分。信号可以电流、电压、气压、液体流量、液体压力、温度、速度、加速度、位置、方向、或其他人。信号路径可以被电线、气动管、液压线,有些机械环节,或是任何一个部件发出了信号传输到另一个地方。组件可能会使用一些的能源增加权力的付出的信号。3.Block Diagrams and Transfer Functions3。框图和转让功能A block diagram consists of a block representing each component in

a control system connected by lines that represent the signal paths. The driver’s sense of provides the two input signals; the position of the automobile and the position of the center of the road. The drivercompares the two positions and determines the positions of thesteering wheel that will maintain the proper position of theautomobile . To implement the decision, the driver’s hands and armsmove the steering wheel to the new position. The automobile responds o the change in steering wheel position with a corresponding change n direction. After a short time has elapsed, the new direction moves e automobile to a new position. Thus, there is a time delay between change in position of the steering and the position of the tomobile. This time delay is include in the mathematical equation of he block representing the automobile. 一个框图上由一个区块代表中的每一个元件线条连接的一个控制系统的代表信号路径司机的意义;提供两个输入信号的位置汽车和中心的位置的道路。司机比较两个位置,并确定的位置方向盘,将保持适当的位置汽车。实施决定,司机双手和胳膊上把方向盘到新的位置。汽车响应方向盘的改变地位相应的变化汽车到一个新的位置。因此,我们之间的一段时间他汽车到一个新的位置。因此,我们之间的一段时间位置的改变的指导与定位汽车。这次延误是包含在数学公式区块代表汽车。The loop in the block diagram indicates a fundamental concept of control. The actual position of the automobile is used to determine the correction necessary to maintain the desired position. This concept is called feedback, and control systems with feedback are called close-loop control systems. Control system that do not have feedback are called open-loop control system because their block diagram does

not have a loop. The most important characteristic of a component is the relationship between the input signal and the output signal. This relationship is expressed by the transfer function of the component, which is defined as the ratio of the output signal divided by the input signal. (Mostly, it is the Laplace transform of the output

signal divided by the Laplace transform of the input signal) 在框图循环显示基本概念的控制。汽车的实际情况用来确定修正必要的去维护所需的位置。这个概念被称为反馈和反馈控制系统被称为闭环控制系统。控制系统没有反馈被称为开环控制系统,因为他们的框图上都是不一样的没有一个循环。最重要的特征之间的关系分量输入信号和输出信号。这种关系是表达的组成、传递函数的定义是输出信号的比率除以输入信号。(主要是,它是拉普拉斯变换的输出4 Open-loop Control开环控制

An open-loop control system does not compare the actual result with the desired result to determine the control action. Instead, a calibrated setting peviously determined by some sort of calibration procedure or calculation----is used to obtain the desired result引入开环控制系统并不比较实际的结果与期望的结果来确定控制行动。相反,校准过的设置,-previously取决于某种校对规程或者计算——以获得期望的结果

The needle valve with a calibrated dial shown in Fig.6.2 is an example of an open-loop control system. The calibration curve is usually obtained by measuring the flow rate for several dial settings. As the calibration curve indicates, different calibration lines are obtained for different pressure drops. Assume that a flow rate of is desired and a setting of S is used. As long as the pressure drop across the valve remains equal to , the flow rate will remain . If the pressure drop changes to , the flow rate will change to . The open-loop control cannot correct for unexpected changes in the pressure drop. 针阀中显示在校准过的拨Fig.6.2就属于一种开环控制系统。通常校准曲线的测量了好几拨流量设置。为曲线表明,不同的校准线,得到了不同压力下降。认为流量的场景,是理想的使用。只要通过阀门的压降仍然相等,流量会留下来。如果压力降的流量变化会改变。不能正确的开环控制的意外变化压降

• The firing of a rifle bullet is anther example of an open-loop

control system .The desired result is to direct the bullet to the bull’s-eye .The actual result is the direction of the bullet after the gun has been fired. The open-loop control occurs when the rifle is aimed at the bull’s-eye and the trigger is pulled . Once the bullet leaves the barrel ,it is on its own : If a sudden gust of wind comes up ,the direction will change and no correction will be possible解雇步子弹是另开环控制系统的例子,期望的结果就是要引导子弹靶心,实际效果是方向子弹后被解雇了。开环控制发生在步旨在靶心和扳机拉起。一旦子弹离开桶,它就在自己的:如果一阵风呈现出来,方向将变化,而没有责备的,必成为可能The primary advantage of open-loop control is that it is less expensive than closed-loop control: it is not necessary to measure the actual result . In addition ,the controller is much simpler because corrective action based on the error is not required . The disadvantage of open-loop control is that errors caused by unexpected disturbances are not corrected . Often a human operator must correct slowly changing disturbances by manual adjustment . In this case , the operator is actually closing the loop by providing the feedback signal . 主要利用开环控制费用较低,闭环控制:这是没有必要去测量实际效果。此外,该控制器是非常简单的因为基于误差纠正措施并不是必须的。开环控制的缺点错误造成意想不到的骚动是不被修正了。经常人类操作员必须正确慢慢改变由手工扰动的调整。在这种情况下,操作者实际上是关闭回路藉由提供反馈信号

5 Close loop Control: Feedback反馈封闭环控制:

• Feedback is the action of measuring the difference between the

actual result and the desired result, and using that difference to drive the actual result toward the desired result. The term feedback comes from the direction in which the measured value signal travels in the block diagram. The signal begins at the output of the controlled system and ends at the input to the controller. The output of the controller is the input to the controlled system. Thus

• •

•

•

•

•

the measured value signal is fed back from the output of the controlled system to the input. The term closed loop refers to loop created by the feedback path反馈的作用是测量实际效果之间的差额,想要的结果,并且利用这一差别驱动实际成果向期望的结果。术语反馈来自方向测量值的信号传播框图。开始的信号的输出,终点控制系统的输入控制器。输出控制器的控制系统的输入。因此,测量值从反馈信号的输出的输入控制系统。这个词是指闭环系统循环反馈路径创造的6.Variable Name 6。变量名称The controlled variable (C) is the process output variable that is to controlled. In a process control system, the controlled variable is usually an output variable that s a good measure of the quality of the product. The most common controlled variables are position, velocity, temperature, pressure level and flow rate. 控制变量(C)是一个过程输出变量也控制。在过程控制系统,控制变量通常是一个输出变量那是一场的好办法产品的质量。最常见的控制变量为定位、速度、温度、压力水平和流量。

The set point (SP) is the desired value of the controlled variable. 压力设置点(p)是期望值的控制变量

The measured variable (Cm) is the measured value of the controlled variable. It is the output of the measuring means and usually differs from the actual of the controlled variable by a small amount. 测量变量(公分)是衡量价值的控制变量。这是输出对测量手段和通常不同于实际的控制变量相少量。

The error (E) is the difference between the setpoint and the measured value of the controlled variable . It is computed according to the equation E=SP-.错误(E)的设定值之间的差别,衡量价值的控制变量。它是根据方程计算E =„

The controller output (V) is the control action intended to drive the measured value of the controlled variable toward the setpoint value ,The control action depends on the error signal (E) and on the control modes used in the controller . 该控制器输出(五)是控制行动打算把衡量价值的控制变量向设定的价值,取决于控制作用误差信号(E)和控制方式用于控制器The manipulated variable (M) is the variable regulated by the final controlling element to achieve the desired value of the controlled variable. Obviously ,the manipulated variable must be capable of effecting a change in the controlled variable . The manipulated variable is one of the input variables of the process. Changes in the load on the process necessitate changes in the manipulated. Variable to maintain a balanced condition .For this reason , the value of the manipulated variable is used as a measure of the load on the process. 被操纵的变量(M)多样化受最后的控制装置达到理想的价值的控制变量。很明显,被操纵的变量必须能造成变化的控制变量。被操纵的变量是一种输入变量的过程。变化过程的负荷的变化必然操控。变量来维护一个平衡状态,因为这个原因,价值的操作变量是用来衡量的负荷过程。

The disturbance variables (D) are process input variables that affect the controlled variable but are not controlled by the control system. Disturbance variables are capable of changing the load on the process and are the main reason for using a closed-loop control system. 干扰变量(D)输入变量的影响过程控制变量但不受控制系统。干扰变量是有能力改变的负荷过程的主要原因,是用闭环控制系统。

The primary advantage of closed-loop control is the potential for more accurate control of the process. There are two disadvantages of closed-loop control:(1)closed-loop control is more expensive than open-loop control, and(2) the feedback feature of a closed-loop control system makes it possible for the system to become unstable. An unstable system produces an oscillation of the controlled variable, often with a very large amplitude. 主要利用闭环控制就是潜在的更精确地控制过程。有两个缺点闭环控制:(1)

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闭环控制的物价也比开环控制,以及(2)反馈的特征的闭环控制系统,使系统变得不稳定。不稳定的系统产生振动的控制变量,通常有一个非常大的振幅 Selected from “Introduction to Control System technology , 4th Ed. , by Robert N. Bateson, Macmillan Publishing Co., 1933”. 选自《导言控制系统技术、第四版)。玛格利特:罗伯特,有限公司,上海社会科学院出版社,贝特森1933年”

Unit 11 Typical Measurement Technology 1 Altitude Measurement 1高度测量

Accurate monitoring of aircraft cruising height is required in order to reduce vertical separation to minimum standard. Interest here focuses on the measurement of the distance between aircraft level and the sea surface level. This distance can be estimated onboard via barometric altimeters or it can be measured—either onboard or in ground stations—via electronic radio wave systems. The indication of the first equipment is referred to as pressure altitude, or simply altitude, whereas that of the second category is referred to as geometric height or simply height. 飞机巡航高度精确的控制要求以减少垂直分离到最低的标准。重点感兴趣的测量飞机之间的距离水平和海平面水平。这个距离估计通过机载altimeters气压或者它能在地面stations-via measured-either或机载电子无线电波系统。第一个设备或信封上注明所称为压力的高度,或简单地高度,而第二类的称为几何高度或简单的高度。

The altitude information at air traffic control (ATC) centers is based on pressure altitude measurement that the aircraft transponder system sends after it receives an appropriate interrogation——known as mode C interrogation——transmitted by a secondary surveillance radar. Actually, the altitude information is an atmospheric pressure measurement transformed to altitude indication through a formula expressing the pressure/altitude relationship. When a flight level is cleared for an aircraft, it actually means that the pilot must keep flying on an isobaric surface. However, the altimetry system may present systematic errors (biases) that are different for each airplane, and that significantly affect safety. Thus, the altimetry system performance as well as the aircraft height keeping performance must be monitored by an independent radar or satellite system. 信息的高度,在空中交通管制中心(ATC)根据压高度测量,飞机的应答机系统发给后都把它珍藏一个适当的审讯——被称为模式C讯问——通过二级监视雷达。实际上,高度的大气压力测量信息转化为高度通过公式显示表达压力/高度的关系。当一个飞行高度是允许飞机时,实际上就意味着飞行员必须不停地飞在一个isobaric表面。然而,altimetry系统系统误差可能出现偏差)(飞机的不同而有所区别,明显影响安全。因此,altimetry系统性能以及飞机高度保持性能均须由的雷达或卫星电视系统 2.Thickness Measurement 2。厚度测量

One can measure thickness on many scales .The galaxy is spiral disk about 100 Em(1020m)thick.. 你可以测量厚度,在许多尺度螺旋星系的约100 Em(1020m磁盘)深

The solar system is pancake-like ,about 1 Tm(1012 m) thick .The rings of Saturn are about 10 km thick .Closer to home ,Earth‘s atmosphere is a spherical shell about 40 km thick ;the weather occurs in the troposphere ,about 12 km thick .The outermost shell of the solid Earth is the crust，about 35 km thick .The ocean has a mean depth of 3.9 km .In the Antarctic，the recently discovered objects believe to be microfossils indicative of ancient Martian life are less than 100 nm thick .In terms of the man-made environment，industry must contend with thickness varying from meters，for construction projects，to millimeters on assemble lines，

to micrometers and nanometers for the solid-state，optical，and coatings industries .Perhaps the most familiar way of measuring thickness is by mechanical means，such as by ruler or caliper .Other means are sometimes called for ,either because both sides of an object are not accessible ,the dimension is either too big or too small for calipers ,the object is too fragile ,too hot ,or too cold for direct contact , or the object is in motion on an assemble line--it may not even be a solid .Thickness may also be a function of position ,as either the object may have originally been made with nonuniform thickness ,deliberately or not ,or the thickness may have become nonuniform with time due either to corrosion ,cracking ,or some other deterioration .The thickness may also be changing with time due to deliberate growth or etching ,as example for thin films .Thus it follows that ,in more general terms ,measuring thickness might require measuring the topography or height profile of two surfaces and taking the different .Alternatively ,the measurement technique may produce a reading directly related to the difference. 太阳系的薄烤饼似的,约需1 Tm(1012米,厚的土星环10公里厚.Closer带回家,地球大气层中约40公里球壳厚;天气发生的对流层中,大约12公里最厚的外壳,固体地球是地壳厚,大约35公里,海洋的平均深度39公里在南极洲,最近发现在对象认为是化石代表古老火星生命在小于100海里厚条款的人造环境,行业必须满足不同厚度从米,建设项目上,毫米组装系列,以便和奈米的固态的跳动、光学、涂料行业最熟悉的方法也许测量厚度用机械的方法,例如由尺还是卡尺是意味着有时被称为,要么因为双方不能获取物体的尺寸,要么是太大或太小都为卡钳,对象很脆,太热或太冷,或直接接触的目的是在运动中,在一个生产线——它并不会在立体图形厚度也可以是一个函数的位置,无论是对象最初可能已经与均匀厚度、故意与否,厚度随时间可能已经变得不均匀腐蚀,要么由于裂,或其他一些恶化,厚度随时间的变化也可能是由于故意生长或腐蚀、为例对薄膜,紧随其后的工作,在更广泛的来说,测量厚度可能需要测量地形或高度两个平面的概况,以不同的.Alternatively、测量技术可能会引起阅读直接关系到的不同 • 3.Distance measurement 3。距离测量

• The tools and techniques of distance measurement are possibly one

of humankind's longest-running inventive pursuits .This chapter concerns itself with methods to measure a relatively small segment of this range-from centimeters to kilometers .Even within this limited segment ,it would hardly be possible to list ,much less describe ,all of the distance measurement approaches that have been devised .Nevertheless ,the small sampling of technologies that are covered here should be of help to a broad range of readers.

• Distance measurement , at its most basic ,is concerned with

determining the length of a unidimensional line joining two points in three-dimensional space . Oftentimes , a collection of distance measurements is called for ,so that shape ,the orientation , or the changes in position of an object can be resolved . therefore , one must consider not only the measurement of distances ,but also their spatial and temporal distributions .The terminology “ranging” will be used in reference to systems that perform single sensor-to-target measurement ,”range-imaging” for systems that collect a dense map or grid of spatially distributed range measurement ,and “position tracking” for systems that record the time history of distance measurement to one or several targets . 工具和技术的距离测量的可能是人类漫长的发明之一。这一章中牵涉到的方法来评估一小部分这range-from公分到公里在这有限的段苦恼,这没有什么可以列表,更不用说描述,所有的距离测量方法设计然而,小抽样技术,在这里盖应该帮助广泛的读者距离测量,在最基础的,涉及确定的长度是一个一维线连接两个点三维空间。很多时候,一家集距离测量,要求的形

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状、取向、或变化的对象的位置都能得到解决。因此,我们必须考虑不仅是测量距离,而且他们的时空分布,术语“范围”将用于参考sensor-to-target测量系统,进行单range-imaging”,“系统,集密集的地图或者网格分布范围空间的方法,以及“位置跟踪”为系统,记录时间历史的距离测量一个或多个目标

4.Level Measurement 4。液位测量

Level is defined as the filling height of a liquid or bulk material, for example, in a tank or reservoir. Generally , the position of the surface is measured relative to a reference plane, usually the tank bottom. If the product’s surface is not flat (e.g., with foam ,waves , turbulences ,or with coarse-grained bulk material) level usually is defined as the average height of a bounded area. 水平是指液体充填高度或散装资料,例如,在一个容器或水库。一般来说,表面的位置测量相对于参考平面,通常在罐底部。如果产品的表面不是平的(例如,有泡沫,波浪,动荡,或用细粒散装材料水平通常是指有界区域的平均高度。

Various classic and modern methods exist to measure product level in process and storage tanks in the chemical, petrocheical , pharmaceutical ,water, and food industries, in mobile tanks on vehicles and ships, but also in natural reservoirs like seas, dams, lakes ,and oceans. Typical tank heights are approximately between 0.5 m and 40m.

Two different tasks can be distinguished:(1)continuous level measurement (level indication ,LI) ,and (2) level switches (LS) (e.g., to detect an alarm limit to prevent overfilling). Fig. 11.1 shows the principal operational modes of level measurement .Every continuous system can also be used as a programmable switch .Many level devices are mounted on top of the tank and measure primarily the distance d between their mounting position and the product’s surface .The level L is then calculated ,defining the tank height h as constant, as shown in fig.11.1 and expressed as:

L=h -d种各样的古典与现代的测量方法存在产品水平和储罐基础施工过程中在化工、petrocheical、医药、水、食品等行业,在移动调车、船,而且在自然水库大坝、海洋、像湖泊和海洋。典型的坦克高度约0.5米之间4000万欧元。两种不同的任务,可以分为:(1)持续的水平测量(要求等级标志,李;及(2)最小的液位开关(例如:用于检测报警,以防止量)。图11.1显示液位测量主要运行方式下的每一处连续系统也可作为一个可编程的开关。许多级设备安装在上面的坦克和测量距离d之间的主要产品的固定点位置的物体,水平计算出L是坦克,定义了高度h为常数,显示在fig.11.1和表示为:我= h - d

Unit 14 Basic Concepts of Communication and Networking 1.Station站点

A station represents a single communicating element on a network system.Each user of the network must access the communication capablility of the network via a station.Each station will typically have some implementation of the open systems interconnection (OSI) network reference model as the means of utilizing the network system. 一个车站为一个沟通网络系统元素网络必须的每个用户访问交流capablility通过网络的一个车站每个站将会实施有一些有特色开放系统互连(OSI)网络方式的参考模型,利用网络系统

2.Media Access 2。媒体访问Media access is the method by which individual stations determine when they are permitted to transmit ,or “use”the media. Media access control (MAC) is a function that is usually performed in the data link layer of the OSI reference model .Some well-known methods of media access

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control include carrier sense multiple access with collision detection (CSMA/CD) and token passing.CSMA/CD systems (such as Ethernet) allow all stations on a network equal access.Each station must “listen” to the network to determine periods of inactivity before transmitting .Any station wishing to use the媒体访问方法确定个人站当他们允许传送、或“使用”媒体。媒体访问控制(MAC)是一种功能,通常是由在数据链路层的OSI参考模型的方法。一些知名媒体访问控制包括载波监听多址和碰撞检测(CSMA / CD)和令牌传球CSMA / CD系统(如以太网)让所有的工作站网络平等的机会每站必须“听”到网络,以确定时间的不活动,在发射信号愿意采用任何车站netwok may begin transmitting providing the network is inactive when it checks for activity.If multiple stations attempt to transmit simultaneously,a collision occurs.This is detected by all transmitting stations,which all must immediately stop transmitting and each wait a randomly determined period of time,before attempting to use the network again.Controller area network (CAN) ,for example,uses a variant of CSMA/CD for media access.Token-passing systems have a logical “token” which is exchanged among stations via network messaging.The station that holds the token has permission to transmit.All other网络可能开始传输提供网络是消极的当它检查活动如果多个站,试图同时传输发生碰撞这是所有检测传输都必须立即停止所有发送和每个等随机决定一段时间,之前先试图利用网络了. 控制器局域网(能),例如,使用CSMA / CD的各种不同的媒体访问Token-passing系统具有相同的逻辑”令牌”,是在以网络信息交换站车站时,保持令牌被允许传送所有其他stations are only permitted to receive messages.Stations wishing to transmit but not having the token must wait until the station holding the token passes it on.Another commonly used method of media access control is masterslave. In this method,one station on the network (designated the master) is generally in charge of,and originates, all communications.Slaves only respond to the master,and only respond when the master initiates communications with them via sending a message to the slave.Profibus-FMS(see below) is an example of a protocol which uses both token passing (in some cases)and master-slave(in some cases)to control media access空间站只被允许接收信息电台希望传送但实际上没有记号必须等到车站记号传递着另一个常用方法的媒体访问控制是适应主从式。在该方法中,网络上的一个火车站大师(指定)是通常负责,渊源,所有的通信只有对奴隶主人,并且只有当主人的提升者的反应与他们沟通通过发送消息给奴隶Profibus-FMS(见下文)是一种典型的协议表示既使用通过(在某些情况下)和主从(在某些情况下,以体访问