光电传感器英文和译文

Progress in Materials ScienceVolume 46, Issues 34, 2001, Pages 461504The selection of sensorsJ Shieh, J.E Huber, N.A Fleck, , M.F AshbyDepartment of Engineering, Cambridge University, Trumpington Street, Cambridge CB2 1PZ, UKAvailable online 14 March 2001.http:/dx.doi.org/10.1016/S0079-6425(00)00011-6, How to Cite or Link Using DOIPermissions & ReprintsAbstractA systematic method is developed to select the most appropriate sensor for a particular application. A wide range of candidate sensors exist, and many are based on coupled electrical and mechanical phenomena, such as the piezoelectric, magnetostrictive and the pyro-electric effects. Performance charts for sensors are constructed from suppliers data for commercially available devices. The selection of an appropriate sensor is based on matching the operating characteristics of sensors to the requirements of an application. The final selection is aided by additional considerations such as cost, and impedance matching. Case studies illustrate the selection procedure.KeywordsSensors; Selection; Sensing range; Sensing resolution; Sensing frequency1. IntroductionThe Oxford English Dictionary defines a sensor as “a device which detects or measures some condition or property, and records, indicates, or otherwise responds to the information received”. Thus, sensors have the function of converting a stimulus into a measured signal. The stimulus can be mechanical, thermal, electromagnetic, acoustic, or chemical in origin (and so on), while the measured signal is typically electrical in nature, although pneumatic, hydraulic and optical signals may be employed. Sensors are an essential component in the operation of engineering devices, and are based upon a very wide range of underlying physical principles of operation.Given the large number of sensors on the market, the selection of a suitable sensor for a new application is a daunting task for the Design Engineer: the purpose of this article is to provide a straightforward selection procedure. The study extends that of Huber et al. 1 for the complementary problem of actuator selection. It will become apparent that a much wider choice of sensor than actuator is available: the underlying reason appears to be that power-matching is required for an efficient actuator, whereas for sensors the achievable high stability and gain of modern-day electronics obviates a need to convert efficiently the power of a stimulus into the power of an electrical signal. The classes of sensor studied here are detailed in the Appendices.2. Sensor performance chartsIn this section, sensor performance data are presented in the form of 2D charts with performance indices of the sensor as axes. The data are based on sensing systems which are currently available on the market. Therefore, the limits shown on each chart are practical limits for readily available systems, rather than theoretical performance limits for each technology. Issues such as cost, practicality (such as impedance matching) and reliability also need to be considered when making a final selection from a list of candidate sensors.Before displaying the charts we need to introduce some definitions of sensor characteristics; these are summarised in Table 1.1 Most of these characteristics are quoted in manufacturers data sheets. However, information on the reliability and robustness of a sensor are rarely given in a quantitative manner.Table 1. Summary of the main sensor characteristicsRangemaximum minus minimum value of the measured stimulusResolutionsmallest measurable increment in measured stimulusSensing frequencymaximum frequency of the stimulus which can be detectedAccuracyerror of measurement, in% full scale deflectionSizeleading dimension or mass of sensorOpt environmentoperating temperature and environmental conditionsReliabilityservice life in hours or number of cycles of operationDriftlong term stability (deviation of measurement over a time period)Costpurchase cost of the sensor ($ in year 2000)Full-size tableIn the following, we shall present selection charts using a sub-set of sensor characteristics: range, resolution and frequency limits. Further, we shall limit our attention to sensors which can detect displacement, acceleration, force, and temperature.2 Each performance chart maps the domain of existence of practical sensors. By adding to the chart the required characteristics for a particular application, a subset of potential sensors can be identified. The optimal sensor is obtained by making use of several charts and by considering additional tabular information such as cost. The utility of the approach is demonstrated in Section 3, by a series of case studies.2.1. Displacement sensorsConsider first the performance charts for displacement sensors, with axes of resolution versus range R, and sensing frequency f versus range R, as shown in Fig. 1 and Fig. 2, respectively.Fig. 1. Resolution versus sensing range for displacement sensors.View thumbnail imagesFig. 2. Sensing frequency versus sensing range for displacement sensors.View thumbnail images2.1.1. Resolution sensing range chart (Fig. 1)The performance regime of resolution versus range R for each class of sensor is marked by a closed domain with boundaries given by heavy lines (see Fig. 1). The upper limit of operation is met when the coarsest achievable resolution equals the operating range =R. Sensors of largest sensing range lie towards the right of the figure, while sensors of finest resolution lie towards the bottom. It is striking that the range of displacement sensor spans 13 orders of magnitude in both range and resolution, with a large number of competing technologies available. On these logarithmic axes, lines of slope +1 link classes of sensors with the same number of distinct measurable positions, . Sensors close to the single position line =R are suitable as simple proximity (on/off) switches, or where few discrete positions are required. Proximity sensors are marked by a single thick band in Fig. 1: more detailed information on the sensing range and maximum switching frequency of proximity switches are summarised in Table 2. Sensors located towards the lower right of Fig. 1 allow for continuous displacement measurement, with high information content. Displacement sensors other than the proximity switches are able to provide a continuous output response that is proportional to the targets position within the sensing range. Fig. 1 shows that the majority of sensors have a resolving power of 103106 positions; this corresponds to approximately 1020 bits for sensors with a digital output.Table 2. Specification of proximity switchesProximity switch typeMaximum switching distance (m)Maximum switching frequency (Hz)Inductive6104110155000Capacitive110361021200Magnetic31038.51024005000Pneumatic cylinder sensors (magnetic)Piston diameter 81033.21013005000Ultrasonic1.21015.2150Photoelectric31033002020,000Full-size tableIt is clear from Fig. 1 that the sensing range of displacement sensors cluster in the region 105101 m. To the left of this cluster, the displacement sensors of AFM and STM, which operate on the principles of atomic forces and current tunnelling, have z-axis-sensing ranges on the order of microns or less. For sensing tasks of 10 m or above, sensors based on the non-contacting technologies of linear encoding, ultrasonics and photoelectrics become viable. Optical linear encoders adopting interferometric techniques can achieve a much higher resolution than conventional encoders; however, their sensing range is limited by the lithographed carrier (scale). A switch in technology accounts for the jump in resolution of optical linear encoders around the sensing range of 0.7 m in Fig. 1.Note that “radar”, which is capable of locating objects at distances of several thousand kilometres,3 is not included in Fig. 1. Radar systems operate by transmitting high-frequency radio waves and utilise the echo and Doppler shift principles to determine the position and speed of the target. Generally speaking, as the required sensing range increases, sensors based on non-contact techniques become the most practicable choice due to their flexibility, fast sensing speed and small physical size in relation to the length scale detected. Fig. 1 shows that sensors based on optical techniques, such as fibre-optic, photoelectric and laser triangulation, cover the widest span in sensing range with reasonably high resolution.For displacement sensors, the sensing range is governed by factors such as technology limitation, probe (or sensing face) size and the material properties of the target. For example, the sensing distance of ultrasonic sensors is inversely proportional to the operating frequency; therefore, a maximum sensing range cut-off exists at about R=50 m. Eddy current sensors of larger sensing face are able to produce longer, wider and stronger electromagnetic fields, which increase their sensing range. Resolution is usually controlled by the speed, sensitivity and accuracy of the measuring circuits or feedback loops; noise level and thermal drift impose significant influences also. Sensors adopting more advanced materials and manufacturing processes can achieve higher resolution; for example, high-quality resistive film potentiometers have a resolution of better than 1 m over a range of 1 m (i.e. 106 positions) whereas typical coil potentiometers achieve only 103 positions.2.1.2. Sensing frequency sensing range chart (Fig. 2)When a displacement sensor is used to monitor an oscillating body, a consideration of sensing frequency becomes relevant. Fig. 2 displays the upper limit of sensing frequency and the sensor range for each class of displacement sensor. It is assumed that the smallest possible sensing range of a displacement sensor equals its resolution; therefore in Fig. 2, the left-hand side boundary of each sensor class corresponds to its finest resolution.4 However, sensors close to this boundary are only suitable as simple switches, or where few discrete positions are to be measured.Lines of slope 1 in Fig. 2 link classes of sensors with the same sensing speed, fR. For contact sensors such as the LVDT and linear potentiometer, the sensing speed is limited by the inertia of moving parts. In contrast, many non-contact sensors utilise mechanical or electromagnetic waves and operate by adopting the time-of-flight approach; therefore, their maximum sensing speed is limited by the associated wave speed. For example, the maximum sensing speed of magnetostrictive sensors is limited by the speed of a strain pulse travelling in the waveguide alloy, which is about 2.8103 m s1.The sensing frequency of displacement sensors is commonly dependent on the noise levels exhibited by the measuring electronic circuits. Additionally, some physical and mechanical limits can also impose constraints. For example, the dynamic response of a strain gauge is limited by the wave speed in the substrate. For sensors with moving mass (for example, linear encoder, LVDT and linear potentiometer), the effects of inertial loading must be considered in cyclic operation. For optical linear encoders the sensing frequency increases with range on the left-hand side of the performance chart, according to the following argument. The resolution becomes finer (i.e. decreases in an approximately linear manner) with a reduced scan speed V of the recording head. Since the sensor frequency f is proportional to the scan speed V, we deduce that f increases linearly with , and therefore f is linear in the minimum range of the device.2.2. Linear velocity sensorsAlthough velocity and acceleration are the first and second derivatives of displacement with respect to time, velocity and acceleration measurements are not usually achieved by time differentiation of a displacement signal due to the presence of noise in the signal. The converse does not hold: some accelerometers, especially navigation-grade servo accelerometers, have sufficiently high stability and low drift that it is possible to integrate their signals to obtain accurate velocity and displacement information.The most common types of velocity sensor of contacting type are electromagnetic, piezoelectric and cable extension-based. Electromagnetic velocity sensors use the principle of magnetic induction, with a permanent magnet and a fixed geometry coil, such that the induced (output) voltage is directly proportional to the magnets velocity relative to the coil. Piezo-velocity transducers (PVTs) are piezoelectric accelerometers with an internal integration circuit which produces a velocity signal. Cable extension-based transducers use a multi-turn potentiometer (or an incremental/absolute encoder) and a tachometer to measure the rotary position and rotating speed of a drum that has a cable wound onto it. Since the drum radius is known, the velocity and displacement of the cable head can be determined.5Optical and microwave velocity sensors are non-contacting, and utilise the optical-grating or Doppler frequency shift principle to calculate the velocity of the moving target. Typical specifications for each class of linear velocity sensor are listed in Table 3.Table 3. Specification of linear velocity sensorsSensor classMaximum sensing range (m/s)Resolution (number of positions)Maximum operating frequency (Hz)Magnetic induction25360510451051001500PVT0.251.3110551057000Sensor classMaximum sensing range (m/s)Resolution (number of positions)Maximum operating frequency (Hz)Cable-extension0.715110511061100Optical and microwave131651105 10,000目录目录1. 简介简介.22. 传感器性能图表传感器性能图表.22.1位移传感器位移传感器 .32.1.1分辨率 - 感应范围图（图 1）.42.1.2.检测频率 检测范围图（图 2）.52.2线性速度传感器线性速度传感器 .6问题 3-4，2001 年第 46 卷，页 461-504 传感器的选择J Shieh, J.E Huber, N.A FleckM.F Ashby剑桥大学工程系，英国剑桥 CB2 的 1PZ，Trumpington 街_摘要摘要对于一个特定的应用系统来说要选择最为合适的传感器。大量种类的传感器存在，并且许多传感器是基于耦合的电气和机械现象，如压电，磁致伸缩和焦电效应。传感器的性能图表是从商用设备供应商提供的数据而来。选择适当的传感器是基于传感器的经营特色，以匹配应用程序要求。最终的选择是根据外加的其他因素，如成本，阻抗匹配。这些案例研究说明了选拔程序。关键词关键词传感器选择感应范围检测分辨率检测频率_1. 简介简介“牛津英语大辞典”定义传感器“一个能够检测测量环境或一些变量，且能够记录，显示，或以其他方式收到信息的设备”。因此，传感器具有将刺激转换成可测量信号的功能。这些刺激可以是力学，热学，电磁学，声学，或起源于化学（等）的刺激，而测得的信号通一般是电信号，虽然气动，液压和光信号也可以采用。基于广泛而最基本物理原理的传感器是工程设备中必不可少的组成部分。考虑到市场上种类繁多的传感器，对于工程设计人员为一个新的应用程序选择合适的传感器是一项艰巨的任务：这篇文章的目的就是提供一套简单的挑选步骤。本研究是对胡贝尔等对执行机构选择问题的延伸和补充。传感器比执行机构具有更为广泛的应用：根本原因，驱动器需要有效的比配功率，而传感器是实现现性电子产品所要求的的高稳定性和增益性并能将其转换成强有效的电信号地刺激。传感器种类的研究将在附录中详细的阐述。2. 传感器性能图表传感器性能图表 在本节中，传感器性能数据以性能为横轴的二维图中进行展示。这些数据是基于当前市场上一般可用的传感系统的。而不是具有工艺理论研究的理论知识。如成本，实用性（如阻抗匹配）和可靠性等问题也需要从备选传感器性能列表中进行对比，然后在做最后的选择。在阐释图表之前，我们需要介绍一些有关传感器特性的定义，在表 1.1 中给出的性能多是厂商会给出的。然而，传感器的可靠性和鲁棒性很少以确定的方式给出表 1.主要传感器的特性总结范围刺激的最大值减最小值分辨率可测量的最小的刺激变化值检测频率可被检测的刺激的最高频率精度测量误差, 以满课度百分比的形式给出尺寸一般传感器的主要规格外界环境温度和环境条件可靠性服务时长活着运行周期漂移长期稳定性（一段时期内的测量偏差）成本采购成本 (2000 年以美元计)全尺寸表在下面，我们将用二维的传感器特性图呈现选项：范围，分辨率和频率的限制。此外，我们应该限制我们的注意力集中于能够测量距离，加速度，力，温度的的传感器。每个性能图展示是的实际存在的应用于各产业中的传感器。通过在图表中添加为特定应用所需的敏感器特性，可以识分辨出传感器的子集。要想选择出最合适的传感器是利用几个图表，并要考虑下面的表格信息如价格。该方法的实用性表现在2.1位移传感器首先考虑位移传感器的性能图表，分辨率 与范围 R 的关系，检测频率 f 与范围 R 的关系，如图 1 和图 2 分别所示。 图 1。位移传感器的分辨率与传感范围的对应系。 图 2。位移传感器的检测频率与传感范围的对应关系。2.1.1分辨率 - 感应范围图（图 1）对于这种传感器的分辨率对感应范围 R 的性能结构是用封闭的的加重的线标记的（见图一）。当可感应的分辨率等于感应范围即 = R 是，。令人吃惊的位移传感器的范围跨越 13 个数量级，大量的竞争技术，在范围和分辨率。在这些数轴，斜坡+1 传感器具有独特的可衡量的职位相同数量的链接类线。接近传感器，以单一的立场是一致的是适合作为简单的接近（开/关）开关，或需要几个分立位置。接近传感器是由一个单一的厚图带标记。 1：最大开关频率接近开关感应范围和更详细的信息汇总表 2。对位于图右下角的传感器。 1 允许连续位移测量，信息含量高。位移传感器，接近开关以外，能够提供连续的输出响应是成正比的感应范围内目标的位置。图 1 可以看出，大多数传感器有 103-106 位置的分辨能力，这对应约 10-20 位数字输出的传感器。表 2。接近开关的规格接近开关类型最大开关距离 (m)最大开关频率（Hz）感应区6104110155000容量110361021200磁性31038.51024005000气缸传感器（磁）活塞直径超声波81033.21013005000超声波1.21015.2150光电31033002020,000全尺寸表从图 1 可以很明显的看到位移传感器的感应范围集中在 10-5-101 米的区域。这 个范围左侧，AFM 和 STM 位移传感器是靠原子力来运行的，并且 Z 轴感应范围在微米级左右。对于测量 10 米或以上的传感任务，传感器基于非接触式的线性编码的超声波的光电技术。光学线性编码器采用干涉测量技术可以比传统的编码器实现更高的分辨率，然而，其感应范围被刻载波（规模）限制。感应范围在 0.7 米左右时的光学线性编码的跳跃是有开关导致的（如图一）。注意，这是能够在数千公里的距离定位对象的“雷达”并不包含在图 1 中。雷达系统通过高频无线电波传输和利用回波和多普勒频移的原则来确定目标的位置和速度的。一般来说，随着所需的感应范围增加，基于非接触技术的传感器成为最可行的选择，由于其灵活性，检测速度快和小尺度检测的物理尺寸。图1 所示，基于光学技术，如光纤，光电，激光三角传感器，以相当高的分辨率覆盖了在感应范围内最广泛跨度。对于位移传感器而言感应范围被如技术，探头（或感应面）的尺寸和材料性能而制约。例如，超声波传感器的检测距离是与工作频率成反比的，因此，最大感应范围存在 R = 50 米处。涡流传感器的感应面较大，能够产生更长，更宽和更强大的电磁场，从而增加其感应范围。分辨率通常被速度，灵敏度和精度的测量电路或反馈回路控制，噪音水平和热漂移征收也有显着影响。传感器采用更先进的材料和制造工艺，可以实现更高的分辨率，例如，高品质的电阻膜电位有超过 1 米（即 106 位置优于 1 微米）范围内的分辨率，而典型的线圈电位只能达到 103 微米。2.1.2.检测频率 检测范围图（图 2）当位移传感器用来监测震荡物体时，检测频率变得至关重要。图 2 显示了检测频率和每类位移传感器传感器范围的上限。据推测，位移传感器 最小的检测范围等于分辨率，因此在图 2 中，每类传感器的左侧边界和分辨率是一致的。然而，只有简单的开关器适合这个边界处的性质，或者用于测量几个有限的距离。图 2 中的斜线 1，用相同的检测速度联系起不同类的传感器，FR，如 LVDT 和线性电位器的接触式传感器，感应速度被运动部件的惯性所限制。与此相反，许多非接触式传感器利用机械或电磁波通过飞速的接收发送来完成，因此，其最大的感应速度是由相关的波速度的限制。例如，传感磁致伸缩传感器的最大速度是被合金的应变脉冲所限制的，其中约 2.8103 m 每秒行驶速度。位移传感器的传感频率一般是通过测量电子电路发出的噪音水平来判定的。此外，一些物理和机械的限制，也可以施加限制。例如，应变计的动态响应是被通过在基板上的波的速度限制的。对于移动传感器（例如，线性编码器，LVDT和线性电位器），必须考虑惯性载荷的影响。对于线性光学编码器检测频率的增加是随着传感性能图表左侧的范围而增加的，根据下面的参数。分辨率提高（即 近似线性地减小）是随着记录头扫描速度 V 减少发生的。我们推断，f的增加是与 成线性的，因此 f 在设备的最小范围时呈线性。2.2线性速度传感器线性速度传感器虽然速度和加速度，是位移对时间的第一和第二变量，速度和加速度的测量通常不容易实现位移信号的测量，这是因为信号中存在噪声分化。反过来不成立：加速度计，尤其是导航级伺服加速度计，有足够高的稳定性和低漂移，这可以集成信号，以获得准确的速度和位移信息。接触式速度传感器的最常见的类型是电磁速度传感器，它基于压电和延长电缆。电磁速度传感器使用永久磁铁和一个固定的几何线圈的磁感应原理，这样的反应（输出）电压正比于线圈磁铁的速度。压电式速度传感器（PVTs）是内部集成电路环生产速度信号。延长电缆为基础的传感器使用多圈电位器（或增量/绝对式编码器）和转速计来测量电缆，旋转位置和旋转速度。由于滚筒的半径是已知的，电缆头的速度和位移可以确定光学和微波速度传感器的非接触式，并利用光纤光栅的多普勒频移原理，计算出移动目标的速度。表 3 列出了每类线性速度传感器的典型规格。传感器类型最大检测范围 (m/s)分辨率 (位置数)最大工作频率 (Hz)磁感应25360510451051001500PVT0.251.3110551057000电缆延伸0.715110511061100光学和微波式131651105 10,000