传感器通信电子工程类外文翻译@中英文翻译@外文文献翻译.doc
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1、What is a smart sensorOne of the biggest advances in automation has been the development and spread of smart sensors. But what exactly is a smart sensor? Experts from six sensor manufacturers define this term. A good working smart sensor definition comes from Tom Griffiths, product manager, Honeywel
2、l Industrial Measurement and Control. Smart sensors, he says, are sensors and instrument packages that are microprocessor driven and include features such as communication capability and on-board diagnostics that provide information to a monitoring system and/or operator to increase operational effi
3、ciency and reduce maintenance costs.No failure to communicate The benefit of the smart sensor, says Bill Black, controllers product manager at GE Fanuc Automation, is the wealth of information that can be gathered from the process to reduce downtime and improve quality. David Edeal, Temposonics prod
4、uct manager, MTS Sensors, expands on that: The basic premise of distributed intelligence, he says, is that complete knowledge of a system, subsystem, or components state at the right place and time enables the ability to make optimal process control decisions. Adds John Keating, product marketing ma
5、nager for the Checker machine vision unit at Cognex, For a (machine vision) sensor to really be smart, it should not require the user to understand machine vision.A smart sensor must communicate. At the most basic level, an intelligent sensor has the ability to communicate information beyond the bas
6、ic feedback signals that are derived from its application. says Edeal. This can be a HART signal superimposed on a standard 4-20 mA process output, a bus system, or wireless arrangement. A growing factor in this area is IEEE 1451, a family of smart transducer interface standards intended to give plu
7、g-and-play functionality to sensors from different makers.Diagnose, program Smart sensors can self-monitor for any aspect of their operation, including photo eye dirty, out of tolerance, or failed switch, says GE Fanucs Black. Add to this, says Helge Hornis, intelligent systems manager, Pepperl+Fuch
8、s, coil monitoring functions, target out of range, or target too close. It may also compensate for changes in operating conditions. A smart sensor, says Dan Armentrout, strategic creative director, Omron Electronics LLC, must monitor itself and its surroundings and then make a decision to compensate
9、 for the changes automatically or alert someone for needed attention. Many smart sensors can be re-ranged in the field, offering settable parameters that allow users to substitute several standard sensors, says Hornis. For example, typically sensors are ordered to be normally open (NO) or normally c
10、losed (NC). An intelligent sensor can be configured to be either one of these kinds.Intelligent sensors have numerous advantages. As the cost of embedded computing power continues to decrease, smart devices will be used in more applications. Internal diagnostics alone can recover the investment quic
11、kly by helping avoid costly downtime.Sensors: Getting into PositionAs the saying goes, No matter where you go, there you are. Still, most applications require a bit more precision and repeatability than that, so heres advice on how to select and locate position sensors.The article contains online ex
12、tra material.Whats the right position sensor for a particular application? It depends on required precision, repeatability, speed, budget, connectivity, conditions, and location, among other factors. You can bet that taking the right measurement is the first step to closing the loop on any successfu
13、l application.Sensor technologies that can detect position are nearly as diverse as applications in providing feedback for machine control and other uses. Spatial possibilities are linear, area, rotational, and three-dimensional. In some applications, theyre used in combination. Sensing elements are
14、 equally diverse. Ken Brey, technical director, DMC Inc., a Chicago-based system integrator, outlined some the following position-sensing options.Think digitally For digital position feedback: Incremental encoders are supported by all motion controllers; come in rotary and linear varieties and in ma
15、ny resolutions; are simulated by many other devices; and require a homing process to reference the machine to a physical marker, and when power is turned off. Absolute encoders are natively supported by fewer motion controllers; can be used by all controllers that have sufficient available digital i
16、nputs; report a complete position within their range (typically one revolution); and do not require homing. Resolvers are more immune to high-level noise in welding applications; come standard on some larger motors; simulate incremental encoders when used with appropriate servo amps; and can simulat
17、e absolute encoders with some servo amps. Dual-encoder feedback, generally under-used, is natively supported by most motion controllers; uses one encoder attached to the motor and another attached directly to the load; and is beneficial when the mechanical connection between motor and load is flexib
18、le or can slip. Vision systems , used widely for inspection, can also be used for position feedback. Such systems locate objects in multiple dimensions, typically X, Y, and rotation; frequently find parts on a conveyor; and are increasing in speed and simplicity. A metal rolling, stamping, and cut-o
19、ff application provides an example of dual-encoder feedback use, Brey says. It required rapid and accurate indexing of material through a roll mill for a stamping process. The roll mill creates an inconsistent amount of material stretch and roller slip, Brey explains. By using the encoder on the out
20、going material as position feedback and the motor resolver as velocity feedback in a dual-loop configuration, the system was tuned stable and a single index move provided an accurate index length. It was much faster and more accurate than making a primary move, measuring the error, then having to ma
21、ke a second correction move, he says.Creative, economical Sam Hammond, chief engineer, Innoventor, a St. Louis, MO-area system integrator, suggests that the applications purpose should guide selection of position sensors; measurements and feedback dont have to be complex. Creative implementations ca
22、n provide simple, economical solutions, he says. For instance, for sequencing, proximity sensors serve well in many instances.Recent sensor applications include the AGV mentioned in lead image and the following. In a machine to apply the top seals to tea containers, proximity and through-beam sensor
23、s locate incoming packages. National Instruments vision system images are processed to find location of a bar code on a pre-applied label, and then give appropriate motor commands to achieve the desired position (rotation) setting to apply one of 125 label types. Two types of position sensors were u
24、sed. One was a simple inductive proximity sensor, used to monitor machine status to ensure various motion components were in the right position for motion to occur. The camera also served as a position sensor, chosen because of its multi purpose use, feature location, and ability to read bar codes.
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