传感器技术外文文献及中文翻译

英文文献及中文翻译一种精确测量倾斜角度的光学传感器摘要本文主要介绍了一种新型光学传感器，它可以同时准确地测量倾斜角或两轴倾斜角度。

这种传感器是基于激光干涉原理，因此具有很高的精度。

设计制作了一个传感器的模型来论证这个新的方法，这是一个光电传感器,传感器中没有移动的部分。

由正交于铅垂面的流动水平面提供参考面。

传感器和绝对水平面之间的角度随着被测量的物体倾斜而改变，这些变化反映在条纹图案的中心位置的转移方式。

不同的干涉条纹的中心位置随倾斜角的变化而改变。

干涉条纹图案进行记录和处理，转化为两轴、水平和垂直倾斜角度。

当使用1024*1024像素的传感器时，测量范围为700弧秒，其精度可高达+/ - 1弧秒。

关键词：倾斜角度传感器，倾斜仪，激光干涉I 介绍市场上目前有几种类型的商业倾斜角度测量传感器。

有些是角度传感器，有些是倾斜仪，它们的工作原理不同。

电解液体、电容和钟摆是现在大多数倾斜角度传感器和倾斜仪的三个主要工作原理。

在这里，我们提出了一种新的光学方法，建立了一个用激光、光学元件和图像传感器的光电传感器，它可以同时做精确的倾斜角度测量，不需要进行机械的移动，其工作原理是基于光学干涉，相干激光作为光源。

光线通过一个装满液态油的玻璃油盒。

由正交于铅垂面的流动水平面提供参考面。

当激光束穿过油箱有两束光线反射回来，一束是液体的表面产生的，另一束是容器玻璃产生的，干涉条纹就是由这两条光线形成的，条纹图案将随着倾斜角度的变化产生相应的变化，条纹图案采集和处理后将反映倾斜角度信息，光学工作原理使它不受磁场的影响。

该传感器可以同时测量两轴倾角。

流动的水平面确保了参考面是一个绝对的水平面。

高灵敏度光学干涉测量原理，保证了较高的精度。

II 原理图1说明了工作原理示意图，O点是光线扩大镜头的焦点，O点可以看作是点光源，它发出球面波。

由于地球重力的影响，液体油面始终保持水平，因此用油面作为参考平面。

该容器是玻璃材料的。

当传感器被放在目标表面时，其底部表面将连同目标对象一起倾斜。

传感器技术论文中英文对照资料外文翻译文献Development of New Sensor TechnologiesSensors are devices that can convert physical。

chemical。

logical quantities。

etc。

into electrical signals。

The output signals can take different forms。

such as voltage。

current。

frequency。

pulse。

etc。

and can meet the requirements of n n。

processing。

recording。

display。

and control。

They are indispensable components in automatic n systems and automatic control systems。

If computers are compared to brains。

then sensors are like the five senses。

Sensors can correctly sense the measured quantity and convert it into a corresponding output。

playing a decisive role in the quality of the system。

The higher the degree of n。

the higher the requirements for sensors。

In today's n age。

the n industry includes three parts: sensing technology。

n technology。

and computer technology。

毕业设计（论文）外文文献翻译文献、资料中文题目：传感器技术文献、资料英文题目：Sensor-technology文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14Sensor technologyA sensor is a device which produces a signal in response to its detecting or measuring a property ,such as position , force , torque , pressure , temperature , humidity , speed , acceleration , or vibration .Traditionally ,sensors (such as actuators and switches )have been used to set limits on the performance of machines .Common examples are (a) stops on machine tools to restrict work table movements ,(b) pressure and temperature gages with automatics shut-off features , and (c) governors on engines to prevent excessive speed of operation . Sensor technology has become an important aspect of manufacturing processes and systems .It is essential for proper data acquisition and for the monitoring , communication , and computer control of machines and systems .Because they convert one quantity to another , sensors often are referred to as transducers .Analog sensors produce a signal , such as voltage ,which is proportional to the measured quantity .Digital sensors have numeric or digital outputs that can be transferred to computers directly .Analog-to-coverter(ADC) is available for interfacing analog sensors with computers .Classifications of SensorsSensors that are of interest in manufacturing may be classified generally as follows:Machanical sensors measure such as quantities aspositions ,shape ,velocity ,force ,torque , pressure , vibration , strain , and mass .Electrical sensors measure voltage , current , charge , and conductivity .Magnetic sensors measure magnetic field ,flux , and permeablity .Thermal sensors measure temperature , flux ,conductivity , and special heat .Other types are acoustic , ultrasonic , chemical , optical , radiation , laser ,and fiber-optic .Depending on its application , a sensor may consist of metallic , nonmetallic , organic , or inorganic materials , as well as fluids ,gases ,plasmas , or semiconductors .Using the special characteristics of these materials , sensors covert the quantity or property measured to analog or digital output. The operation of an ordinary mercury thermometer , for example , is based on the difference between the thermal expansion of mercury and that of glass.Similarly , a machine part , a physical obstruction , or barrier in a space can be detected by breaking the beam of light when sensed by a photoelectric cell . A proximity sensor ( which senses and measures the distance between it and an object or a moving member of a machine ) can be based on acoustics , magnetism , capacitance , or optics . Other actuators contact the object and take appropriate action ( usually by electromechanical means ) . Sensors are essential to the conduct of intelligent robots , and are being developed with capabilities that resemble those of humans ( smart sensors , see the following ).This is America, the development of such a surgery Lin Bai an example, through the screen, through a remote control operator to control another manipulator, through the realization of the right abdominal surgery A few years ago our country theexhibition, the United States has been successful in achieving the right to the heart valve surgery and bypass surgery. This robot has in the area, caused a great sensation, but also, AESOP's surgical robot, In fact, it through some equipment to some of the lesions inspections, through a manipulator can be achieved on some parts of the operation Also including remotely operated manipulator, and many doctors are able to participate in the robot under surgery Robot doctor to include doctors with pliers, tweezers or a knife to replace the nurses, while lighting automatically to the doctor's movements linked, the doctor hands off, lighting went off, This is very good, a doctor's assistant.Tactile sensing is the continuous of variable contact forces , commonly by an array of sensors . Such a system is capable of performing within an arbitrarythree-dimensional space .has gradually shifted from manufacturing tonon-manufacturing and service industries, we are talking about the car manufacturer belonging to the manufacturing industry, However, the services sector including cleaning, refueling, rescue, rescue, relief, etc. These belong to the non-manufacturing industries and service industries, so here is compared with the industrial robot, it is a very important difference. It is primarily a mobile platform, it can move to sports, there are some arms operate, also installed some as a force sensor and visual sensors, ultrasonic ranging sensors, etc. It’s surrounding environment for the conduct of identification, to determine its campaign to complete some work, this is service robot’s one of the basic characteristicsIn visual sensing (machine vision , computer vision ) , cameral optically sense the presence and shape of the object . A microprocessor then processes the image ( usually in less than one second ) , the image is measured , and the measurements are digitized ( image recognition ) .Machine vision is suitable particularly for inaccessible parts , in hostile manufacturing environments , for measuring a large number of small features , and in situations where physics contact with the part may cause damage .Small sensors have the capability to perform a logic function , to conducttwo-way communication , and to make a decisions and take appropriate actions . The necessary input and the knowledge required to make a decision can be built into a smart sensor . For example , a computer chip with sensors can be programmed to turn a machine tool off when a cutting tool fails . Likewise , a smart sensor can stop a mobile robot or a robot arm from accidentally coming in contact with an object or people by using quantities such as distance , heat , and noise .Sensor fusion . Sensor fusion basically involves the integration of multiple sensors in such a manner where the individual data from each of the sensors ( such as force , vibration , temperature , and dimensions ) are combined to provide a higher level of information and reliability . A common application of sensor fusion occurs when someone drinks a cup of hot coffee . Although we take such a quotidian event for granted ,it readily can be seen that this process involves data input from the person's eyes , lips , tongue , and hands .Through our basic senses of sight , hearing , smell , taste , and touch , there is real-time monitoring of relative movements , positions , and temperatures . Thus if the coffee is too hot , the hand movement of the cup toward the lip is controlled and adjusted accordingly .The earliest applications of sensor fusion were in robot movement control , missile flight tracking , and similar military applications . Primarily because these activities involve movements that mimic human behavior . Another example of sensor fusion is a machine operation in which a set of different but integrated sensors monitors (a) the dimensions and surface finish of workpiece , (b) tool forces , vibrations ,and wear ,(c) the temperature in various regions of the tool-workpiece system , and (d) the spindle power .An important aspect in sensor fusion is sensor validation : the failure of one particular sensor is detected so that the control system maintains high reliability . For this application ,the receiving of redundant data from different sensors is essential . It can be seen that the receiving , integrating of all data from various sensors can be a complex problem .With advances in sensor size , quality , and technology and continued developments in computer-control systems , artificial neural networks , sensor fusion has become practical and available at low cost .Movement is relatively independent of the number of components, the equivalent of our body, waist is a rotary degree of freedom We have to be able to hold his arm, Arm can be bent, then this three degrees of freedom, Meanwhile there is a wrist posture adjustment to the use of the three autonomy, the general robot has six degrees of freedom. We will be able to space the three locations, three postures, the robot fully achieved, and of course we have less than six degrees of freedomFiber-optic sensors are being developed for gas-turbine engines . These sensors will be installed in critical locations and will monitor the conditions inside the engine , such as temperature , pressure , and flow of gas . Continuous monitoring of the signals from thes sensors will help detect possible engine problems and also provide the necessary data for improving the efficiency of the engines .传感器技术传感器一种通过检测某一参数而产生信号的装置。

中英文资料外文翻译文献英文:The right design for a relative humidity sensor systemOptimizing the response characteristics and accuracy of a humidity sensor system1 OverviewTo make the right choice when selecting a relative humidity sensor for an application, it is important to know and to be able to judge the deciding factors. In addition to long-term stability, which is a measure on how much a sensor changes its properties over time, these factors also include the measurement accuracy and the response characteristics of the sensor. Capacitive humidity sensors are based on the principle that a humidity-sensitive polymer absorbs or releases moisture as a function of the relative ambient humidity. Because this method is only a spot measurement at the sensor location, and usually the humidity of the surroundings is the desired quantity, the sensor must be brought into moisture equilibrium with the surroundings to obtain a precise measurement value. This process is realized by various transport phenomena (cf. the section titled "The housing effect on the response time"), which exhibit a time constant. Accuracy and response time are thus closely dependent on each other, and the design of a humidity measurement system becomes a challenge.2Measurement accuracyThe term measurement accuracy of a humidity sensor is understood primarily to refer to the deviation of the value measured by the sensor from the actual humidity. To determine the measurement accuracy, references, such as chilled mirror hygrometers, whose own tolerance must be taken into account, are used. In addition to this trivial component, humidity sensors require a given time for reaching stable humidity and temperature equilibrium (the humidity is a function of temperature and decreases with increasing temperature; a difference between sensor and ambient temperature leads to measurement errors). This response time thus has a significant effect on the value measured by the sensor and thus on the determinedaccuracy.This time-dependent characteristic is explained in more detail in the following.3Response characteristics and response timeThe response characteristics are defined by various parameters. These are:●The actual response characteristics of the humidity sensor at constant temperature.(1) How quickly the sensitive polymer absorbs or releases moisture until equilibrium is reached (intrinsic response time)(2) How fast the entire system reaches humidity equilibrium (housing effect)●The thermal response characteristics of the humidity sensor at a non-constant temperature(3) The thermal mass of the sensor(4) The system's thermal mass, which is thermally coupled to the sensor (e.g. printed circuit board)(5) Heat sources in the direct surroundings of the sensor (electronic components)(1) and (3) are determined entirely by the sensor itself, (1) primarily by the characteristics of the sensitive polymer.(2) and (4) are primarily determined by the construction of the entire system (shape and size of housing andreadout circuitry).(5) is determined by heat-emitting electronic components.These points will be discussed in more detail in the following.The intrinsic response time (1)Qualitatively, the response characteristics of capacitive humidity sensors look like the following (Fig. 1).Fig. 1: Typical and idealized response characteristics of capacitive humidity sensors (schematic)Because these response characteristics are especially pronounced at high humidity values, an isothermal humidity jump from 40% to 100% was selected here for illustration. The desired ideal behavior of the sensor is indicated in blue. In practice, however, the sensor behaves according to the red line, approximately according to:RH-t=(E-S)*(1-e)+S（t）Here, the time span 1 is usually very short (typ. 1 – 30 min.), in contrast, the time span 2 is very long (typ. Many hours to days). Here the connection of measurement accuracy and response characteristics becomes clear (t until RH=100% is reached). The value at t4 (Fig. 1) is considered to be an exact measured value. However, this assumes that both the humidity and also the temperature remain stable during this entire time, and that the testing waits until this very long measurement time is completed. These conditions are both very hard to achieve and unusual in practice. For the calibration, there are the following two approaches, which both find use in practice (cf. Fig. 2):1.The measured value at t2 (Fig. 1) is used as a calibration reference.Advantage:●The required measurement time for reaching the end value (in the example 100%) isclearly shortened,corresponds to practice, and achieves an apparent short responsetime of the sensor (cf. Fig. 2).Disadvantage:●If the conditions are similar for a long time (e.g., wet periods in outdoor operation),the sensors exceed the correct end value (in the example 100%) undesirably by upto 10% (cf. Fig. 2).2. The measured value at t4 (Fig. 1) is used as a calibration reference.Advantage:●Even for similar conditions over a long time (e.g., wet periods in outdoor operation),an exact measurement result is obtained (cf. Fig. 2).Disadvantage:●For a humidity jump like in Fig. 1, the sensors very quickly deliver the measuredvalue at t2, but reaching a stable end value (about 3-6% higher) takes a long time(apparent longer response time)(cf. Fig. 2).In order to take into account both approaches optimally, the measured values at t3 (cf. Fig. 1) are used as the calibration reference by Sensirion AG.Fig. 2: Response characteristics of different humidity measurement systemsThe housing effect on the response time (2)Here, two types of transport phenomena play a deciding role:●Convection: For this very fast process, the air, whose humidity is to be determined,is transported to the sensor by means of ventilation.●Diffusion: This very slow process is determined by the thermal, molecularself-motion of the water molecules. It occurs even in "stationary" air (e.g., within ahousing), but leads to a long response time.In order to achieve favorable response characteristics in the humidity measurement system, the very fast convection process must be supported by large housing openings and the slow diffusion process must be supported by a small housing around the sensor (small "deadvolume") with "stationary" air reduced to a minimum. The following applies:Thermal effects (3), (4), and (5)Because the total thermal mass of the humidity measurement system (sensor + housing)has a significant effect on its response time, the total thermal mass must be kept as low aspossible. The greater the total thermal mass, the more inert the measurement system becomesthermally and its response time, which is temperature-dependent, increases. In order toprevent measurement errors, the sensor should not be mounted in the vicinity of heatgenerating components.4Summary –what should be taken into account when designing a humidity measurement systemIn order to achieve error-free operation of a humidity-measurement system with response times as short as possible, the following points should be taken into account especially for the selection of the sensor and for the design of the system.●The selection of the humidity sensor element. It should●be as small as possible,●have a thermal mass that is as low as possible,●work with a polymer, which exhibits minimal fluctuations in measured values duringthe time span 2(cf. Fig. 1); testing gives simple information on this condition,●provide calibration, which corresponds to the requirements (see above), e. g.,SHT11/SHT15 from Sensirion.●The housing design (cf. Formula 1). It should●have air openings that are as large as possible in the vicinity of the sensor or thesensor should be operated outside of the housing à good convection!●enclose a "dead volume" that is as small as possible around the sensor àlittlediffusion!●The sensor should be decoupled thermally as much as possible from other components,so that the response characteristics of the sensor are not negatively affected by the thermal inertia of the entire system.(e.g., its own printed circuit board for the humidity sensor, structurally partitioning the housing to create a small volume for the humidity sensor, see Fig. 3)Fig. 3: Mounting example for Sensirion sensors SHT11 and SHT15 with slits for thermal decoupling●The sensor should not be mounted in the vicinity of heat sources. If it was, measuredtemperature would increase and measured humidity decrease.5Design proposalThe challenge is to realize a system that operates cleanly by optimally taking into account all of the points in section 4. The already calibrated SMD humidity sensors SHT11 and SHT15 from Sensirion are the ideal solution. For optimum integration of the sensors in a measurement system, Sensirion AG has also developed a filter cap as an adapter aid, which takes into account as much as possible the points in section 4 and also protects the sensor against contaminants with a filter membrane. Fig. 4 shows schematically how the sensors can be ideally integrated into a housing wall by means of the filter cap SF1.Fig. 4: Filter cap for SHT11 and SHT15In addition to the advantages mentioned above, there is also the option of building an IP67-compatible humidity measurement device (with O-ring, cf. Fig. 4) with optimal performance. Detailed information is available on the Sensirion Web site.译文：相对湿度传感器系统的正确设计湿度传感器系统精度及响应特性的优化1.综述为了在相对湿度的应用方面对传感器做出正确的选择，了解和评估那些起决定作用的因素是非常重要的。

(文档含英文原文和中文翻译)中英文对照翻译译文:无线传感器网络的实现及在农业上的应用1引言无线传感器网络（Wireless Sensor Network ,WSN）就是由部署在监测区域内大量的廉价微型传感器节点组成，通过无线通信方式形成的一个多跳的自组织的网络系统。

其目的是协作地感知、采集和处理网络覆盖区域中感知对象的信息，并发送给观察者。

“传感器、感知对象和观察者”构成了网络的三个要素。

这里说的传感器，并不是传统意义上的单纯的对物理信号进行感知并转化为数字信号的传感器，它是将传感器模块、数据处理模块和无线通信模块集成在一块很小的物理单元，即传感器节点上，功能比传统的传感器增强了许多，不仅能够对环境信息进行感知，而且具有数据处理及无线通信的功能。

借助传感器节点中内置的形式多样的传感器件，可以测量所在环境中的热、红外、声纳、雷达和地震波信号等信号，从而探测包括温度、湿度、噪声、光强度、压力、土壤成分、移动物体的大小、速度和方向等等众多我们感兴趣的物质现象。

无线传感器网络是一种全新的信息获取和信息处理模式。

由于我国水资源已处于相当紧缺的程度,加上全国90%的废、污水未经处理或处理未达标就直接排放的水污染,11%的河流水质低于农田供水标准。

水是农业的命脉,是生态环境的控制性要素,同时又是战略性的经济资源,因此采用水泵抽取地下水灌溉农田,实现水资源合理利用,发展节水供水,改善生态环境,是我国目前精确农业的关键，因此采用节水和节能的灌水方法是当今世界供水技术发展的总趋势。

2无线传感器网络概述2.1无线传感器网络的系统架构无线传感器网络的系统架构如图1所示，通常包括传感器节点、汇聚节点和管理节点。

传感器节点密布于观测区域，以自组织的方式构成网络。

传感器节点对所采集信息进行处理后，以多跳中继方式将信息传输到汇聚节点。

然后经由互联网或移动通信网络等途径到达管理节点。

终端用户可以通过管理节点对无线传感器网络进行管理和配置、发布监测任务或收集回传数据。

中英文对照翻译外文资料Moving Object Counting with an Infrared Sensor NetworkAbstractWireless Sensor Network (WSN) has become a hot research topic recently. Great benefit can be gained through the deployment of the WSN over a wide range ofapplications, covering the domains of commercial, military as well as residential. In this project, we design a counting system which tracks people who pass through a detecting zone as well as the corresponding moving directions. Such a system can be deployed in traffic control, resource management, and human flow control. Our design is based on our self-made cost-effective Infrared Sensing Module board which co-operates with a WSN. The design of our system includes Infrared Sensing Module design, sensor clustering, node communication, system architecture and deployment. We conduct a series of experiments to evaluate the system performance which demonstrates the efficiency of our Moving Object Counting system.Keywords:Infrared radiation，Wireless Sensor Node1.1 Introduction to InfraredInfrared radiation is a part of the electromagnetic radiation with a wavelength lying between visible light and radio waves. Infrared have be widely used nowadaysincluding data communications, night vision, object tracking and so on. People commonly use infrared in data communication, since it is easily generated and only suffers little from electromagnetic interference. Take the TV remote control as an example, which can be found in everyone's home. The infrared remote control systems use infrared light-emitting diodes (LEDs) to send out an IR (infrared) signal when the button is pushed. A different pattern of pulses indicates the corresponding button being pushed. To allow the control of multiple appliances such as a TV, VCR, and cable box, without interference, systems generally have a preamble and an address to synchronize the receiver and identify the source and location of the infrared signal. To encode the data, systems generally vary the width of the pulses (pulse-width modulation) or the width of the spaces between the pulses (pulse space modulation). Another popular system, bi-phase encoding, uses signal transitions to convey information. Each pulse is actually a burst of IR at the carrier frequency.A 'high' means a burst of IR energy at the carrier frequency and a 'low' represents an absence of IR energy. There is no encoding standard.However, while a great many home entertainment devices use their own proprietary encoding schemes, some quasi-standards do exist. These include RC-5, RC-6, and REC-80. In addition, many manufacturers, such as NEC, have also established their own standards.Wireless Sensor Network (WSN) has become a hot research topic recently. Great benefit can be gained through the deployment of the WSN over a wide range ofapplications, covering the domains of commercial, military as well as residential. In this project, we design a counting system which tracks people who pass through a detecting zone as well as the corresponding moving directions. Such a system can be deployed in traffic control, resource management, and human flow control. Our design is based on our self-made cost-effective Infrared Sensing Module board which co-operates with a WSN. The design of our system includes Infrared Sensing Module design, sensor clustering, node communication, system architecture and deployment. We conduct a series of experiments to evaluate the system performance which demonstrates the efficiency of our Moving Object Counting system.1.2 Wireless sensor networkWireless sensor network (WSN) is a wireless network which consists of a vast number of autonomous sensor nodes using sensors to monitor physical or environmental conditions, such as temperature,acoustics, vibration, pressure, motion or pollutants, at different locations. Each node in a sensor network is typically equipped with a wireless communications device, a small microcontroller, one or more sensors, and an energy source, usually a battery. The size of a single sensor node can be as large as a shoebox and can be as small as the size of a grain of dust, depending on different applications. The cost of sensor nodes is similarly variable, ranging from hundreds of dollars to a few cents, depending on the size of the sensor network and the complexity requirement of the individual sensor nodes. The size and cost are constrained by sensor nodes, therefore, have result in corresponding limitations on available inputs such as energy, memory, computational speed and bandwidth. The development of wireless sensor networks (WSN) was originally motivated by military applications such as battlefield surveillance. Due to the advancement in micro-electronic mechanical system technology (MEMS), embedded microprocessors, and wireless networking, the WSN can be benefited in many civilian application areas, including habitat monitoring, healthcare applications, and home automation.1.3 Types of Wireless Sensor NetworksWireless sensor network nodes are typically less complex than general-purpose operating systems both because of the special requirements of sensor network applications and the resource constraintsin sensor network hardware platforms. The operating system does not need to include support for user interfaces. Furthermore, the resource constraints in terms of memory and memory mapping hardware support make mechanisms such as virtual memory either unnecessary or impossible to implement. TinyOS [TinyOS] is possibly the first operating system specifically designed for wireless sensor networks. Unlike most other operating systems, TinyOS is based on an event-driven programming model instead of multithreading. TinyOS programs are composed into event handlers and tasks with run to completion-semantics. When an external event occurs, such as an incoming data packet or a sensor reading, TinyOS calls the appropriate event handler to handle the event. The TinyOS system and programs are both written in a special programming language called nesC [nesC] which is an extension to the C programming language. NesC is designed to detect race conditions between tasks and event handlers. There are also operating systems that allow programming in C. Examples of such operating systems include Contiki [Contiki], and MANTIS. Contiki is designed to support loading modules over the network and supports run-time loading of standard ELF files. The Contiki kernel is event-driven, like TinyOS, but the system supports multithreading on a per-application basis. Unlike the event-driven Contiki kernel, the MANTIS kernel is based on preemptive multithreading. With preemptive multithreading, applications do not needto explicitly yield the microprocessor to other processes.1.4 Introduction to Wireless Sensor NodeA sensor node, also known as a mote, is a node in a wireless sensor network that is capable of performing processing, gathering sensory information and communicating with other connected nodes in the network. Sensor node should be in small size, consuming extremely low energy, autonomous and operate unattended, and adaptive to the environment. As wireless sensor nodes are micro-electronic sensor device, they can only be equipped with a limited power source. The main components of a sensor node include sensors, microcontroller, transceiver, and power source. Sensors are hardware devices that can produce measurable response to a change in a physical condition such as light density and sound density. The continuous analog signal collected by the sensors is digitized by Analog-to-Digital converter. The digitized signal is then passed to controllers for further processing. Most of the theoretical work on WSNs considers Passive and Omni directional sensors. Passive and Omni directional sensors sense the data without actually manipulating the environment with active probing, while no notion of “direction” involved in these measurements. Commonly people deploy sensor for detecting heat (e.g. thermal sensor), light (e.g. infrared sensor), ultra sound (e.g. ultrasonic sensor), or electromagnetism (e.g. magnetic sensor). In practice, a sensor node can equip with more than one sensor.Microcontroller performs tasks, processes data and controls the operations of other components in the sensor node. The sensor node is responsible for the signal processing upon the detection of the physical events as needed or on demand. It handles the interruption from the transceiver. In addition, it deals with the internal behavior, such as application-specific computation.The function of both transmitter and receiver are combined into a single device know as transceivers that are used in sensor nodes. Transceivers allow a sensor node to exchange information between the neighboring sensors and the sink node (a central receiver). The operational states of a transceiver are Transmit, Receive, Idle and Sleep. Power is stored either in the batteries or the capacitors. Batteries are the main source of power supply for the sensor nodes. Two types of batteries used are chargeable and non-rechargeable. They are also classified according to electrochemical material used for electrode such as NiCd(nickel-cadmium), NiZn(nickel-zinc), Nimh(nickel metal hydride), and Lithium-Ion. Current sensors are developed which are able to renew their energy from solar to vibration energy. Two major power saving policies used areDynamic Power Management (DPM) and Dynamic V oltage Scaling (DVS). DPM takes care of shutting down parts of sensor node which are not currently used or active. DVS scheme varies the power levelsdepending on the non-deterministic workload. By varying the voltage along with the frequency, it is possible to obtain quadratic reduction in power consumption.1.5 ChallengesThe major challenges in the design and implementation of the wireless sensor network are mainly the energy limitation, hardware limitation and the area of coverage. Energy is the scarcest resource of WSN nodes, and it determines the lifetime of WSNs. WSNs are meant to be deployed in large numbers in various environments, including remote and hostile regions, with ad-hoc communications as key. For this reason, algorithms and protocols need to be lifetime maximization, robustness and fault tolerance and self-configuration. The challenge in hardware is to produce low cost and tiny sensor nodes. With respect to these objectives, current sensor nodes usually have limited computational capability and memory space. Consequently, the application software and algorithms in WSN should be well-optimized and condensed. In order to maximize the coverage area with a high stability and robustness of each signal node, multi-hop communication with low power consumption is preferred. Furthermore, to deal with the large network size, the designed protocol for a large scale WSN must be distributed.1.6 Research IssuesResearchers are interested in various areas of wireless sensornetwork, which include the design, implementation, and operation. These include hardware, software and middleware, which means primitives between the software and the hardware. As the WSNs are generally deployed in the resources-constrained environments with battery operated node, the researchers are mainly focus on the issues of energy optimization, coverage areas improvement, errors reduction, sensor network application, data security, sensor node mobility, and data packet routing algorithm among the sensors. In literature, a large group of researchers devoted a great amount of effort in the WSN. They focused in various areas, including physical property, sensor training, security through intelligent node cooperation, medium access, sensor coverage with random and deterministic placement, object locating and tracking, sensor location determination, addressing, energy efficient broadcasting and active scheduling, energy conserved routing, connectivity, data dissemination and gathering, sensor centric quality of routing, topology control and maintenance, etc.中文译文移动目标点数与红外传感器网络摘要无线传感器网络(WSN)已成为最近的一个研究热点。

外文翻译中英文对照翻译智能红外传感器跟上不断发展的工艺技术对工艺工程师来说是一向重大挑战。

再加上为了保持目前迅速变化的监测和控制方法的过程的要求，所以这项任务已变得相当迫切。

然而，红外温度传感器制造商正在为用户提供所需的工具来应付这些挑战：最新的计算机相关的硬件、软件和通信设备，以及最先进的数字电路。

其中最主要的工具，不过是新一代的红外温度计---智能传感器。

今天新的智能红外传感器代表了两个迅速发展的结合了红外测温和通常与计算机联系在一起的高速数字技术的科学联盟。

这些文书被称为智能传感器，因为他们把微处理器作为编程的双向收发器。

传感器之间的串行通信的生产车间和计算机控制室。

而且因为电路体积小，传感器因此更小，简化了在紧张或尴尬地区的安装。

智能传感器集成到新的或现有的过程控制系统，从一个新的先进水平，在温度监测和控制方面为过程控制方面的工程师提供了一个直接的好处。

1 集成智能传感器到过程线同时广泛推行的智能红外传感器是新的，红外测温已成功地应用于过程监测和控制几十年了。

在过去，如果工艺工程师需要改变传感器的设置，它们将不得不关闭或者删除线传感器或尝试手动重置到位。

当然也可能导致路线的延误，在某些情况下，是十分危险的。

升级传感器通常需要购买一个新单位，校准它的进程，并且在生产线停滞的时候安装它。

例如，某些传感器的镀锌铁丝厂用了安装了大桶的熔融铅、锌、和/或盐酸并且可以毫不费力的从狭窄小道流出来。

从安全利益考虑，生产线将不得不关闭，并且至少在降温24小时之前改变和升级传感器。

今天，工艺工程师可以远程配置、监测、处理、升级和维护其红外温度传感器。

带有双向RS - 485接口或RS - 232通信功能的智能模型简化了融入过程控制系统的过程。

一旦传感器被安装在生产线，工程师就可以根据其所有参数来适应不断变化的条件，一切都只是从控制室中的个人电脑。

举例来说，如果环境温度的波动，或程序本身经历类型、厚度、或温度的改变，所有过程工程师需要做的是定制或恢复保存在计算机终端的设置。

无线微传感器中英文对照外文翻译文献(文档含英文原文和中文翻译)A Simple Energy Model for Wireless Microsensor TransceiversAbstract—This paper describes the modelling of shortrange transceivers for microsensor applications. A simple energy model is derived and used to analyze the transceiver battery life. This model takes into account energy dissipation during the start-up, receive, and transmit modes. It shows that there is a significant fixed cost in the transceiver energy consumption and this fixed cost can be driven down by increasing the data rate of the transceiver.I. IntroductionWireless microsensor networks can provide short-range connectivity with significant fault tolerances. These systems find usage in diverse areas such as environmental monitoring, industrial process automation, and field surveillance. As an example, Table I shows a detailed specification for a sensor system used in a factory machine monitoring environment.The major characteristics of a microsensor system are high sensor density, short range transmissions, and low data rate. Depending on the application, there can also be stringent BER and latency requirements. Due to the large density and the random distributed nature of these networks, battery replacement is a difficult task. In fact,a primary issue that prevents these networks to be used in many application areas is the short battery life. Therefore, maximizing the battery life time of the sensor nodes is important. Figure 1 shows the peak current consumption limit when a 950mAh battery is used as the energy source. As seen in the figure, battery life can vary by orders of magnitude depending on the duty cycle of each operation. To allow for higher maximum peak current, it is desirable to have the sensor remain in the off-state for as long as possible.However, the latency requirement of the system dictates how often the sensor needs to be active. For the industrial sensor application described above, the sensor needs to operate every 5ms to satisfy the latency requirement.Assuming that the sensor operates for 100µs every 5ms, the duty cycle is 2%. To achieve a one-year battery life, the peak current consumption must be kept under 5.4mA, which translates to approximately 10mW at 2V supply.This is a difficult target to achieve for sensors that communicate at giga-Hertz carrier frequencies.There has been active research in microsensor networks over the past years. Gupta [1] and Grossglauser [2] established information theoretic bounds on the capacity of ad-hoc networks. Chang [3] and Heinzelman [4] suggested algorithms to increase overall network life-time by spreading work loads evenly among all sensors. Much of the work in this area, especially those that deal with energy consumption of sensor networks, require an energy model [5]. This paper develops a realistic energy model based on the power consumption of a state of the art Bluetoothtransceiver [6]. This model provides insights into how to minimize the power consumption of sensor networks and can be easily incorporated into work that studies energy limited wireless sensor networks. The outline of this paper is as follows. Section II derives the transceiver model. Section III applies this model to analyzing the battery life time of the Bluetooth transceiver.Section IV investigates the dependencies in the model and shows how to modify the design of the Bluetooth transceiver to improve the battery life. Section V shows the battery life improvement realized by applying the results in Section IV. Section VI summarizes the paper.II. Microsensor Transceiver ModellingThis section derives a simple energy model for low power microsensors. Figure 2 shows the model of the sensor node.It includes a sensor/DSP unit for data processing, D/A and A/D for digital-to-analog and analog-to-digital conversion, and a wireless transceiver for data communication. The sensor/DSP, D/A, and A/D operate at low frequency and consume less than 1mW. This is over an order of magnitude less than the power consumption of the transceiver. Therefore, the energy model ignores the contributions from these components. The transceiver has three modes of operation: start-up, receive, and transmit. Each mode will be described and modelled.A. Start-up ModeWhen the transceiver is first turned on, it takes some time for the frequency synthesizer and the VCO to lock to the carrier frequency. The start-up energy can be modelled as follows:where P LO is the power consumption of the synthesizer and the VCO. The term t start is the required settling time. RF building blocks including PA, LNA, and mixer have negligible start-up time and therefore can remain in the off-state during the start-up mode.B. Receive ModeThe active components of the receiver includes the low noise amplifier (LNA), mixer, frequency synthesizer, VCO, intermediate-frequency (IF) amplifier (amp), and demodulator (Demod). The receiver energy consumption can be modelled as follows:where P RX includes the power consumption of the LNA,mixer, IF amplifier, and demodulator. The receiver power consumption is dictated by the carrier frequency and the noise and linearity requirements. Once these parameters are determined, to the first order the power consumption can be approximated as a constant, for data rates up to 10’s of Mb/s. In other words, the power consumption is dominated by the RF building blocks that operate at the carrier frequency. The IF demodulator power varies with data rate, but it can be made small by choosing a low IF.C. Transmit ModeThe transmitter includes the modulator (Mod), frequency synthesizer and VCO (shared with the receiver), and power amplifier (PA). The data modulates the VCO and produces a FSK signal at the desired data rate and carrier frequency. A simple transmitter energy model is shown in Equation (3). The modulator consumes very little energy and therefore can be neglected.P LO can be approximated as a constant. P PA depends on additional factors and needs to be modelled more carefully as follows:where η is the PA efficiency, r is the data rate, d is the transmission distance, and n is the path loss exponent. γPA is a factor that depends on E b /N O , noise factor F of the receiver, link margin L mar , wavelength of the carrier frequency λ, and th e transmit/receive antenna gains G T ,G R :From Equations (3) and (4), the transmitter power consumption can be written as a constant term plus a variable term. The energy model thus becomesIII. Bluetooth TransceiverHere we demonstrate how the above model can be used to calculate the battery life time of a Bluetooth transceiver [6]. This is one of the lowest power Bluetooth transceivers reported in literature. The energy consumption of the transceiver depends on how it operates. Assuming a 100-bit packet is received and a 100-bit packet is transmitted every 5ms, Figure 3 showsthe transceiver activity within one cycle of operation.The transceiver takes 120µs to start up. Operating at 1Mb/s, the receiver takes 100µs to receive the packet. The transceiver then switches to the transmit mode and transmits a same-length packet at the same rate. A 10µs interval, t switch , between the receive and the transmit mode is allowed to switch channel or to absorb any transient behavior. Therefore, the energy dissipated in one cycle of operation is simplyBoth the average power consumption and the duty cycle can be found From Figure 3. Knowing that the transceiver operates at 2V, the life time for a 950mAh battery is calculated to be approximately 2-months.IV. Energy OptimizationThe microsensor system described in Section I requires a battery life of one year or better. Although the Bluetooth transceiver described in the last section falls short of this requirement, it serves as a starting point for making improvements. This section examines E op in detail and suggests ways to increase the battery life by considering both circuit and system improvements. A.Start-up EnergyThe start-up energy can be a significant part of the total energy consumption, especially when the transceiver is used to send short packets in burst mode. For the Bluetooth transceiver, E start accounts for 20% of E op .The start-up energy becomes negligible if the following condition is held true:For the receive/transmit scheme shown in Figure 3, the right hand-side of Equation (8)is evaluated to be approximately 450µs. To keep E start an order of magnitude below E op , it is desirable to have a start-up time of less than 45µs. Cho has demonstrated a 5.8GHz frequency synthesizer im- plementation with a start-up time under 20µs [7].B. Power AmplifierThe PA power consumption is given bywhere η is the power efficiency and P out is the RF output power. P out can be determined by link-budget analysis. For a Bluetooth transceiver, the required P out is 1mW [8].This enables a maximum transmission distance of 10 meters, which is adequate for microsensor applications. Note that P out is small as compared to P LO . The Bluetooth transceiver discussed in Section II has a maximum RF output power of 1.6mW and a PA power consumption of 10mW, sothe efficiency is at 16%. At frequencies around 2GHz, the PA efficiency can vary from 10% [9] to 70% [10] depending on linearity, circuit topology, and technology. Since FSK signal has a constant envelope, nonlinea r PA’s can be used so that better efficiency can be achieved. As will be shown in the next section, PA efficiency has a significant impact on the battery life.C. Data RateAssuming a packet of length L pkt is transmitted at dat rate r, then the transmit time isThe transmitter energy consumption can be re-written asEquation (12) shows that the contribution of the fixed cost P LO can be reduced by increasing the data rate. The energy per bit, E bit , is defined as E op divided by the total number of bits received and sent during one cycle of operation. Assuming a packet of length L pkt is received and a packet of the same length is transmitted, E bit can be found by dividing Equation (7) by 2L pkt . Substituting the appropriate expressions for E start , E rx , and E tx and re-arranging the terms, we getThe first term in Equation (13) is the start-up energy cost. The second term is the PA energy cost. The third term is the cost of the rest of the transceiver electronics during the transmit and receive modes. Note that this term is divided by the data rate r. Figure 4 shows E bit as a function of data rate. The two solid curves have start-up time 120µs and PA efficiencies 10% and 70%, respectively. The two dotted curves have start-up time 20µs and efficiencies 10% and 70%, respectively. At low data rate, E bit is dominated by the fixed cost (the 3rd term in Equation (13)). At high data rate, the start-up energy and the PA energy dominates, so in order to increase battery life, good circuit design techniques need to be applied to minimize the start-up time and to maximize the PA efficiency.Figure 5 shows the impact of PA efficiency on the battery life at a data rate of 10Mb/s. At t start = 120µs, the startup energy is so large that the battery life is limited to 7month even if the PA reaches 100% efficiency. At t start =20µs, the battery life is much improved. The PA efficiency needs to be higher than about 30% to have a 1-year or better battery life. This is certainly achievable as discussed previously in the PA section.V. Performance ImprovementThere are three apparent results from the previous section. First, the data rate should be increased to reduce the fixed cost. Second, the start-up time should be minimized. Third, PA efficiency should be maximized. Figure 6 shows the transceiver activity for a transceiver that has 20µs start-up time and 10Mb/s data rate. The power consumption of the electronics are kept the same as in the Bluetooth transceiver except for the PA. The maximum RF output power is set at 10mW to accommodate the higher data rate, and the PA efficiency is assumed to be 50%. The switching time is kept at 10µs, although this is a conservative since the switching time is likely to be shorter for a faster frequency synthesizer. The E op of this transceiver is 8x lower than that of theBluetooth transceiver. The battery life-time extends from 2-months to approximately1.3 years.VI. ConclusionThis paper describes the modelling of short-range transceivers for wireless sensor applications. This model takes into account energy dissipation during the start-up, transmit, and receive modes. This model is first used to analyze the battery life of a state of the art Bluetooth transceiver, and then it is used to optimize E op . This paper shows that the battery life can be improved significantly by increasing the data rate, reducing the start-up time, and improving the PA efficiency. Increasing the data rate drives down the fixed energy cost of the transceiver. Reducing the start-up time decreases the start-up energy overhead. Improving the PA efficiency lowers the energy per bit cost of the PA.一个简单的能量无线微传感器的接收机模型摘要—本文描述了微传感器的近程的收发器的造型的应用程序。

附录A: 英文文献与中文参考译文At89S51 monolithic integrated circuit is the low power loss which ATMEL Corporation promotes, the high performance CMOS8 position monolithic integrated circuit, internal including the 4K bytes programmable Flash read-only program memory, the component uses the ATMEL Corporation's high density, the non-volatility storage technology production, compatible standard 8051 command systems and pin, and already may use the online programming (ISP), also the available conventional routes carry on the programming and the general 8 microprocessors in the monolithic integrated circuit chip, the ATMEL Corporation's function is formidable, the low end AT89S51 monolithic integrated circuit provides many high performance-to-price ratios the application situations, but applies nimbly in each kind of control domain, the debugging is convenient.The sensor marched the automobile, medical, the industry and astronautics application domain on a large scale. Perhaps you not yet saw any changes . In safe, convenient, aspect day by day aggregate demands and so on entertainment as well as efficiency factor, in addition from all over the world politics the government office's law will enable sensor's application to obtain the unprecedented inflation.Besides estimated that sensor in wireless and consumable domain application sudden inflation, you will also understand why passed on the feeling producer to finish the rapid development huge market and the application domain hopefully before 2010. In these sensors the majority will be microcomputer electrical system series (MEMS) and the micro system technology (MST) type, as well as application prospect very broad micro sensor. regarding the automobile system, the sensor producer may discover the massive sensing application very easily, not only includes the survey to pass on the feeling pressure, moreover including through sensing system survey inertia, position, proximity, temperature, speed of flow, strength strong , tensity, torque, vibration and inclined condition. Uses in surveying these parameters the sensing technology to be various. Passes to believe with automobile technology center technical personnel Alex Cade that “the automobile domain's sensing demand is assuming the caper type to increase to be long.”He enumer ated the chassis control, the vehicles localization/position, the object survey, the vision to strengthen, the automobile environment to heat up , well ventilated, sensor's and so on airconditioning as well as engine and transmission control growth domains. The enhancement vehicles stability is only in numerous example one which his enumerates. US National highway Transportation Administrative bureau (NHTSA) vehicle increased recently about the side collision security aerocyst's proposition request in each steam on the two to six sensors. Although this proposition has not been forced the request use, but American, European and date the this automobile producer indicated that stemming from the security concern, they will finish before 2010 leans for all vehicles installment the surface collision security aerocyst. Certain automobile supplier, like TRW and Delphi ( the latter reaction rate the former quick) apply group of accelerometers and the pressure transmitter in the side collision security aerocyst. the automobile inertia sensing has become other hot spot. In fact, Motorola and Analog Devices () proposed that the use inertia sensor element group will manage massive will use in the vehicles tendency, guidance , the security and the electron s teering application sensing function (illustration 1). “the anti-lock braking system, the electronic braking force distribution system, follow the mark control system and of the initiative yaw control system interaction enable the automobile to have the dy namic stability,” Analog Devices said high-level using Engineer Harvey Weinberg. Motorola John P. Schuster adds: “the part group method may use core platform support many kinds of applications. It take astronautics gyroscope as the foundation, and the cost is low, the volume is small, may apply in the automobile.” light sensing technology budding the one kind used in the survey engine pressure by the Optrand development the new method using one kind of multi-purpose equipment, this equipment loaded one based on the optical fiber technology's pressure transmitter to use in diesel engine's preheating plug. Forced induction the preheating plug by one induction, a fiber optics and many signal control electronic component is composed, when the pressure surpasses 5 Pakistan , it refers to the frequency changer to be able water-cooled to provide 62% precisions, when the pressure is lower than 5 Pakistan, the error is lower than 0.2 Pakistan. this company estimated that will use this equipment for the first time in 2007. the Honeywell plan uses the light sensing technology in low cost's non-key input's passive system, the part uses this technique the technique the product to be possible to insert automobile's door knob. This sensor will contain one to be loaded with transceiver key shape optics Yuan . In order to enter in the vehicle, the vehicle owner has laid aside a key shapepart between the vehicle door knob and the automobile body. the Hall effect sensor will find in the numerous automobile functions applies the place, including induction deceleration and brake pedal's position, cam shaft position and rotational speed, barometric pressure as well as branch pipe absolute pressure (MAP). Infineon Technologies AG application Engineer Werner Roessler believed that active Hall effect sensor available in power transmission control as well as cam and crank and so on related application. “compares with the passive sensor, this has provided the higher accuracy, the better start strategy, and has surveys the crank to start a position ability,” he said. Melexis the Inc. plan uses in this technology inducing the non-contact position. new induction model the electric field induction use electrode and between them the electric field works. Freescale Semiconductor believed that its may use for to substitute the security aerocyst and other use sensor. “this induction method is helpful in makes the security aerocyst to intellectualize, because had not only considered passenger's forehead position (i.e. forehead whether to move?), moreover had considered passenger's volume and the weight, the aerocyst premature will not open,” Freescale application Engineer Don Laybourn said. this kind of sensor may install, in the border or other places have on electrode's steering wheel, like this may determine that the steering wheel is is loosened otherwise (for example, when a pilot falls asleep or cripples when), will then send out the warning signal. This method type may also let the vehicles with the stop slowly down. the vehicles seat electrode may when the vehicles go determined that in the pilot position nobody's situation carries on the brake to the vehicles. this will prevent the vehicles to enter the out of control condition, for example, when the automobile anchors when the pitch. The glass rain water and accumulates the frost to induce is other one kind of application.参考译文：单片机是ATMEL公司推出的低功耗，高性能CMOS8位单片机，片内含4K bytes 的可编程的Flash只读程序存储器，器件采用ATMEL公司的高密度、非易失性存储技术产生，兼容标准8051指令系统及引脚，并且既可采用在线编程（ISP），也可用传统方法进行编程及通用8位微处理器于单片机芯片中，ATMEL 公司的功能强大，低价位的AT89S51单片机提供许多高性价比的应用场合，可灵活应用于各种控制领域，调试非常方便，使用也非常灵活。

中英文对照外翻译Basic knowledge of transducersA transducer is a device which converts the quantity being measured into an optical, mechanical, or-more commonly-electrical signal. The energy-conversion process that takes place is referred to as transduction.Transducers are classified according to the transduction principle involved and the form of the measured. Thus a resistance transducer for measuring displacement is classified as a resistance displacement transducer. Other classification examples are pressure bellows, force diaphragm, pressure flapper-nozzle, and so on.1、Transducer ElementsAlthough there are exception ,most transducers consist of a sensing element and a conversion or control element. For example, diaphragms,bellows,strain tubes and rings, bourdon tubes, and cantilevers are sensing elements which respond to changes in pressure or force and convert these physical quantities into a displacement. This displacement may then be used to change an electrical parameter such as voltage, resistance, capacitance, or inductance. Such combination of mechanical and electrical elements form electromechanical transducing devices or transducers. Similar combination can be made for other energy input such as thermal. Photo, magnetic and chemical,giving thermoelectric, photoelectric,electromaanetic, and electrochemical transducers respectively.2、Transducer SensitivityThe relationship between the measured and the transducer output signal is usually obtained by calibration tests and is referred to as the transducer sensitivity K1= output-signal increment / measured increment . In practice, the transducer sensitivity is usually known, and, by measuring the output signal, the input quantity is determined from input= output-signal increment / K1.3、Characteristics of an Ideal TransducerThe high transducer should exhibit the following characteristicsa) high fidelity-the transducer output waveform shape be a faithful reproduction of the measured; there should be minimum distortion.b) There should be minimum interference with the quantity being measured; the presence of the transducer should not alter the measured in any way.c) Size. The transducer must be capable of being placed exactly where it is needed.d) There should be a linear relationship between the measured and the transducer signal.e) The transducer should have minimum sensitivity to external effects, pressure transducers,for example,are often subjected to external effects such vibration and temperature.f) The natural frequency of the transducer should be well separated from the frequency and harmonics of the measurand.4、Electrical TransducersElectrical transducers exhibit many of the ideal characteristics. In addition they offer high sensitivity as well as promoting the possible of remote indication or mesdurement. Electrical transducers can be divided into two distinct groups:a) variable-control-parameter types,which include:i)resistanceii) capacitanceiii) inductanceiv) mutual-inductance typesThese transducers all rely on external excitation voltage for their operation.b) self-generating types,which includei) electromagneticii)thermoelectriciii)photoemissiveiv)piezo-electric typesThese all themselves produce an output voltage in response to the measurand input and their effects are reversible. For example, a piezo-electric transducer normally produces an output voltage in response to the deformation of a crystalline material; however, if an alternating voltage is applied across the material, the transducer exhibits the reversible effect by deforming or vibrating at the frequency of the alternating voltage.5、Resistance TransducersResistance transducers may be divided into two groups, as follows:i) Those which experience a large resistance change, measured by using potential-divider methods. Potentiometers are in this group.ii)Those which experience a small resistance change, measured by bridge-circuit methods. Examples of this group include strain gauges and resistance thermometers.5.1 PotentiometersA linear wire-wound potentiometer consists of a number of turns resistance wire wound around a non-conducting former, together with a wiping contact which travels over the barwires. The construction principles are shown in figure which indicate that the wiperdisplacement can be rotary, translational, or a combination of both to give a helical-type motion. The excitation voltage may be either a.c. or d.c. and the output voltage is proportional to the input motion, provided the measuring device has a resistance which is much greater than the potentiometer resistance.Such potentiometers suffer from the linked problem of resolution and electrical noise. Resolution is defined as the smallest detectable change in input and is dependent on thecross-sectional area of the windings and the area of the sliding contact. The output voltage is thus a serials of steps as the contact moves from one wire to next.Electrical noise may be generated by variation in contact resistance, by mechanical wear due to contact friction, and by contact vibration transmitted from the sensing element. In addition, the motion being measured may experience significant mechanical loading by the inertia and friction of the moving parts of the potentiometer. The wear on the contacting surface limits the life of a potentiometer to a finite number of full strokes or rotations usually referred to in the manufacture’s specification as the ‘number of cycles of life expectancy’, a typical value being 20*1000000 cycles.The output voltage V0 of the unload potentiometer circuit is determined as follows. Let resistance R1= xi/xt *Rt where xi = input displacement, xt= maximum possible displacement, Rt total resistance of the potentiometer. Then output voltage V0= V*R1/(R1+( Rt-R1))=V*R1/Rt=V*xi/xt*Rt/Rt=V*xi/xt. This shows that there is a straight-line relationship between output voltage and input displacement for the unloaded potentiometer.It would seen that high sensitivity could be achieved simply by increasing the excitation voltage V. however, the maximum value of V is determined by the maximum power dissipation P of the fine wires of the potentiometer winding and is given by V=(PRt)1/2 .5.2 Resistance Strain GaugesResistance strain gauges are transducers which exhibit a change in electrical resistance in response to mechanical strain. They may be of the bonded or unbonded variety .a) bonded strain gaugesUsing an adhesive, these gauges are bonded, or cemented, directly on to the surface of the body or structure which is being examined.Examples of bonded gauges arei) fine wire gauges cemented to paper backingii) photo-etched grids of conducting foil on an epoxy-resin backingiii)a single semiconductor filament mounted on an epoxy-resin backing with copper or nickel leads.Resistance gauges can be made up as single elements to measuring strain in one direction only,or a combination of elements such as rosettes will permit simultaneous measurements in more than one direction.b) unbonded strain gaugesA typical unbonded-strain-gauge arrangement shows fine resistance wires stretched around supports in such a way that the deflection of the cantilever spring system changes the tension in the wires and thus alters the resistance of wire. Such an arrangement may be found in commercially available force, load, or pressure transducers.5.3 Resistance Temperature TransducersThe materials for these can be divided into two main groups:a) metals such as platinum, copper, tungsten, and nickel which exhibit and increase in resistance as the temperature rises; they have a positive temperature coefficient of resistance.b) semiconductors, such as thermistors which use oxides of manganese, cobalt, chromium, or nickel. These exhibit large non-linear resistance changes with temperature variation and normally have a negative temperature coefficient of resistance.a) metal resistance temperature transducersThese depend, for many practical purpose and within a narrow temperature range, upon the relationship R1=R0*[1+a*(b1-b2)] where a coefficient of resistance in ℃-1,and R0 resistance in ohms at the reference temperature b0=0℃ at the reference temperature range ℃.The international practical temperature scale is based on the platinum resistance thermometer, which covers the temperature range -259.35℃ to 630.5℃.b) thermistor resistance temperature transducersThermistors are temperature-sensitive resistors which exhibit large non-liner resistance changes with temperature variation. In general, they have a negative temperature coefficient. For small temperature increments the variation in resistance is reasonably linear; but, if large temperature changes are experienced, special linearizing techniques are used in the measuring circuits to produce a linear relationship of resistance against temperature.Thermistors are normally made in the form of semiconductor discs enclosed in glass vitreous enamel. Since they can be made as small as 1mm,quite rapid response times are possible.5.4 Photoconductive CellsThe photoconductive cell , uses a light-sensitive semiconductor material. The resistance between the metal electrodes decrease as the intensity of the light striking the semiconductor increases. Common semiconductor materials used for photo-conductive cells are cadmium sulphide, lead sulphide, and copper-doped germanium.The useful range of frequencies is determined by material used. Cadmium sulphide is mainly suitable for visible light, whereas lead sulphide has its peak response in the infra-red regionand is, therefore , most suitable for flame-failure detection and temperature measurement. 5.5 Photoemissive CellsWhen light strikes the cathode of the photoemissive cell are given sufficient energy to arrive the cathode. The positive anode attracts these electrons, producing a current which flows through resistor R and resulting in an output voltage V.Photoelectrically generated voltage V=Ip.RlWhere Ip=photoelectric current(A),and photoelectric current Ip=Kt.BWhere Kt=sensitivity (A/im),and B=illumination input (lumen)Although the output voltage does give a good indication of the magnitude of illumination, the cells are more often used for counting or control purpose, where the light striking the cathode can be interrupted.6、Capacitive TransducersThe capacitance can thus made to vary by changing either the relative permittivity, the effective area, or the distance separating the plates. The characteristic curves indicate that variations of area and relative permittivity give a linear relationship only over a small range of spacings. Thus the sensitivity is high for small values of d. Unlike the potentionmeter, the variable-distance capacitive transducer has an infinite resolution making it most suitable for measuring small increments of displacement or quantities which may be changed to produce a displacement.7、Inductive TransducersThe inductance can thus be made to vary by changing the reluctance of the inductive circuit. Measuring techniques used with capacitive and inductive transducers:a)A.C. excited bridges using differential capacitors inductors.b)A.C. potentiometer circuits for dynamic measurements.c) D.C. circuits to give a voltage proportional to velocity for a capacitor.d) Frequency-modulation methods, where the change of C or L varies the frequency of an oscillation circuit.Important features of capacitive and inductive transducers are as follows:i)resolution infiniteii) accuracy+- 0.1% of full scale is quotediii)displacement ranges 25*10-6 m to 10-3miv) rise time less than 50us possibleTypical measurands are displacement, pressure, vibration, sound, and liquid level.8、Linear Variable-differential Ttransformer9、Piezo-electric Transducers10、Electromagnetic Transducers11、Thermoelectric Transducers12、Photoelectric Cells13、Mechanical Transducers and Sensing Elements传感器的基础知识传感器是一种把被测量转换为光的、机械的或者更平常的电信号的装置。