英语、技术两不误---中英对照版传感器运行理论

Duang！楼主这几天一直想着该给大家分享些什么技术干货，然后今天早上突发奇想，想着给大家分享一篇中英对照版的传感器运行理论吧。之所以有这想法，是因为OMEGA工业测量的工程师曾对楼主交流说，为了在自动化或仪器仪表领域能大放光彩，咱一定得把英语专业术语和行话学好呀！所以楼主想，是不是很多这个行业的工程师们或者终端使用者都有这样的需求呢？楼主手头上正好有OMEGA工业测量美国总公司写的结合产品分析的技术文章，还是纯英文哒！因此，楼主鼓起勇气，费了九牛二虎之力，翻译了几篇，想给大家分享分享！楼主对于自动化行业也只能算是新手，技术上面也只算浅尝辄止，若有译得不对的地方，还请各位担待指出来呀，楼主也虚心学习！无论是看英文原版学英文术语，还是看中文学技术，还是看中英文成为行业大腕，希望亲们各取所需，希望对大家有所帮助！楼主也是试着这样来发帖子分享，如果大家觉着不错，可以留言，我会再来几篇这样中英对照的技术文章。谢谢大家反馈！话不多说，直接上内容啦！

Sensor Theory of Operation

传感器运行理论

What makes transducers and load cells work?

传感器和测压元件是如何工作的？

Omega Engineering is a reliable source for pressure transducers and load cells that provide high quality data in a myriad of processes.  In order for pressure sensors and load cells to provide the information our customers are seeking, the pressure or force of that process must reach a sensing element. The sensing element reacts to the force or pressure of the process, creating an output signal that can be interpreted by a read-out device or a data-collection device.  The sensing element, therefore, is the heart of the transducer or load cell.

OMEGA工业测量是传感器和测压元件可靠的供应商，它为大量的过程控制提供高质量的数据。为使压力传感器和测压元件能给客户提供需要的信息，过程中的压力或力必须到达传感元件。传感元件对过程中的力或压力做出反应，生成一个可被读数装置或数据采集装置解读的输出信号。因此，传感元件是传感器或测压元件的核心部分。

图一

The Measurement System

测量系统

The measurement system is made up of a sensing element with four strain gages applied to it.  The strain gages are configured in a Wheatstone bridge, where all 4 resistors (labeled R1 thru R4 in Figure 2) are equal, and change by equal magnitude proportionally, when strain is applied. The greater the force or strain (input), the greater the output. A Wheatstone bridge device requires 4 wires for its connection, positive and negative excitation, and positive and negative sensor output.

该测量系统是由含四个应变片的传感元件组成。应变片配置在含四个对等电阻器（如图2中的R1至R4所示）的单臂电桥中。当施加应变时，四个应变片同等发生跟应变成比例的变化。输入的力或应变越多，输出就越大。一个单臂电桥设备需要四条金属丝来连接，即正负激励，和正负传感输出。

For a typical pressure sensor, the deflection of a diaphragm produces a strain gage output. Depending on the strain gage technology the output can vary from 1 to 3 millivolts per volt (mV/V) to as much as 10 to 30mV/V. To calculate your full scale output, you would multiply the output of the sensor by the voltage used to power the device. For example, for a 3 mV/V sensor, if we used 10 volts DC as our excitation voltage, we would expect to get 3mv/V x 10 V = 30 mv at full scale.

对于一个典型的压力传感器，膜片的偏差产生一个应变片输入。依靠应变片技术，输出可从1到3毫伏每伏（mV/V）,多至10到30 mV/V。为计算您的满量程输出，您可以把传感器的输出乘以设备使用的电源电压。例如，对于一个3 mV/V的传感器，如果我们采用10伏DC作为我们的激励电压，我们将预期得到3mv/V x 10 V = 30 mv的满量程。

图三：Typical Reaction of Diaphragm When Pressure is Applied. 施加压力时膜片典型的反应

Examples

示例

One good example of this sensor theory is the PX4600.  The pressure from the process that the customer is trying to measure will be brought to the diaphragm element through an access port.  The pressure will cause a deflection of a diaphragm, stressing the Wheatstone bridge arrangement on the other side of the diaphragm, and creating a mV/V output.  This millivolt signal is then read by a device capable of accepting a millivolt signal or to an amplifier or signal conditioner for further signal processing.

这种传感器理论的一个极好例子是PX4600。客户尝试测量的来自过程的压力将通过接入端口带至膜片元件。压力将会引起膜片的偏差，并在膜片的另一面对单臂电桥布置加压，生成一个mV/V输出。该毫伏信号被可接收毫伏信号的设备读出，或者被放大器或者信号调整器读出以进行进一步的信号处理。

Pressure Applied Through Access Port:

通过接入端口施加的压力

Pressure Sensed by Element: Signal Generated Output to PX409-USBH:

元件传输的压力；传至PX409-USBH的输出信号

Figure 4- Example of Wheatstone Bridge Sensing Element on a Board Mountable Transducer

图4—面板安装传感器上的单臂电桥传感元件示例

The PX409-USBH has a USB connector at the end of its cable for direct input into a laptop computer.  The onboard electronics process the signal into a convenient, easy to use communication protocol. For a plug and play experience, use our free software that is available on our website.  A unit can be connected to a laptop which will display and collect data while providing power to the sensor itself. 

PX409-USBH在电缆的末端有一个USB连接头，可直接连接至手提电脑。机载电子设备把信号传输至一个方便、易于使用的通信协议中。为获取即插即用的体验，可至我们网站下载免费的软件。您还可把一个装置连接至手提电脑，这样当给传感器供电时，就可在电脑上显示和收集信息。

Omega Software - Charting Window: OMEGA软件-图表窗口

PX409-USBH和USBH Connector: USBH和连接头

The DPG409 digital pressure gage uses a digital output in its wireless transmitter versions.  This allows the readings from a remote line of sight location without having to run signal wire.  A wireless receiver will accept this signal and display or log the data.

DPG409数字压力计在无线传输器的型号中采用了数字输出，这样不需信号线就可远程获取读数。一个无线接收器将接收信号，并显示或记录数据。

Sensor Categories

传感器类型

Omega Pressure sensors fall into one of 3 categories:  Unamplified, Amplified, and Digital.

Omega压力传感器可分成三类：未放大型、放大型和数字型。

1）Unamplified：未放大型

Most load cells have an unamplified output.  Unamplified outputs are common with devices that are too small to be equipped with signal condition electronics, or where the environment is too extreme for electronics to survive. This is the case with the PX1004, PX1005, and PX1009 products, which are unamplified due to the very high and very low operational temperatures in which they are designed to function.  Unamplified sensors have a rather short transmission distance capability, usually  no longer than 20-30 feet.  This is because the signal strength is so small. This also makes them susceptible to electromagnetic noise from the surrounding environment.   

大部分测压元件都具有未放大的输出。未放大的输出在较小且无法安装信号电子设备的装置中很常见，在电子设备很难正常运行的极端环境中也十分常见。PX1004和PX1005就是这样未放大的类型，它们是专为超高或超低工作温度设计的。未放大的传感器具有相对较小的传输距离，一般不超过20-30英尺，这是因为信号强度太弱，而且易受周围环境电磁噪声的干扰。

2）Amplified：放大型

Amplified sensors use internal signal conditioning electronics to create a stronger signal.  This makes them less susceptible to environmental noise and capable of going longer distances to their receiving units.  Sensors with internal amplifiers have a smaller operational temperature range due to temperature restrictions of the signal conditioning electronics inside the sensor.  Current output sensors can send their amplified signal as much as 1000 feet and still provide high accuracy.  In general, voltage output sensors can maintain accuracy under 100 feet.

放大型的传感器利用内部信号电子设备，产生一个更强大的信号。这使得它们不易受到环境噪声的干扰且能传输较远的距离到达它们的接收装置。带内部放大器的传感器因其内部的信号电子设备有温度限制，因此具有较小的操作温度。电流输出传感器可以把放大的信号进行远达1000英尺的传送，且仍具有较高的精度。一般而言，电压输出传感器可以在100英尺范围内可保证精度。

3）Digital：数字型

The 3rd type of sensor, as categorized by output, is a digital output sensor.  This type of output has the potential to provide the lowest noise and longest transmission distances available. There are a number of communication styles available, such as the DPG409 and the PX 409-USBH or RS485 devices.

以输出分类的第三种传感器是数字输出传感器。这种输出有提供最低噪声和最长传输距离的潜力。这类传感器有多种类型可供选择，如DPG409、PX409-USBH或RS485设备。

Accuracy Considerations

精度考虑

Typical 5-point Calibration 

典型5点校准

Total Error Band

综合误差范围

This is the band maximum deviation for any output when considering all defined sources of error, such as vibration or temperature or humidity.  It is expressed as a percentage of the rated output.

若把所有明确的误差来源都考虑在内，比如振动、温度或湿度，就能得到该任何输出类型的最大偏差范围。该偏差通常以额定输出的百分比来表示。

Static Accuracy

静态精度

The combined effects of linearity, hysteresis, and repeatability, Static Accuracy is expressed as ±% of span, and is in reference to the BSL. The static error band is a good measure of the accuracy that can be expected from a pressure senor or load cell at a constant temperature.

在线性度、滞后性和重复性的联合效应下，静态精度以范围的±%来表示，并且根据BSL（最佳直线性）而定。

BSL (Best Straight Line)

BSL（最佳直线性）

BSL is the maximum error deviation from a terminal-base line, divided in half.  To determine this line, the outputs from zero and full-scale are used to create a line. The other data points are measured based on distance from this line. The Best Straight Line is the line that has the same slope as the terminal-base line, but is offset so that that the errors are equally split on either side of the BSL.  The Best Straight Line is used to describe performance for linearity.

最佳直线型是选取偏离基准线最大偏离值的中间值。要确定最佳直线，首先需要建立一条0位至满量程的基准直线。然后，再选择0位至满量程中的多个点位，这些测量值可能会偏离这条基准直线。从这些测量点中选出一条与基准直线斜率相同的直线，并且选取最大偏差值的中间值，这条直线就是最佳直线。最佳直线具有良好的线性关系。

Non-Linearity

非线性

This is the maximum deviation of the calibration curve from a straight line drawn between the no-load and rated outputs. It is expressed as a percentage of the rated output and measured on increasing pressure load only.

校准曲线和空载到额定输出直线之间的最大偏差就是非线性。它以额定输出的百分比表示，并且只在增加的压力负荷上测量。

Hysteresis

滞后性

Hysteresis is the maximum difference between output readings for the same applied pressure, approached from opposite directions. It is determined by comparing outputs for a pressure value, first obtained by approaching from lower pressure and then by approaching from a higher pressure. The closer the 2 readings are, the lower the hysteresis.  This error is difficult to correct.

滞后性就是从两个相反方向施加同一压力的输出读数的最大差异。通过比较从低压获取的和从高压获取的输出压力值，可决定滞后性。这两个读数越靠近，则滞后性越低。该误差很难修正。

Repeatability

重复性

The maximum difference between output readings for repeated pressure loads, under identical load and environmental conditions, is called Repeatability. The closer these readings are, the better the Repeatability.  This error cannot be corrected.

重复性是同一负载在同一环境条件下反复测量的输出读数的最大差异。读数越接近，则重复性越好。该误差不能被修正。