Although technological advancements have improved sensors since their first use, their purpose ultimately remains constant. "Sensors are called sensors for a reason," says Tony Udelhoven, director, sensors division at Turck (www.turck.com). "They are quite literally the sensory system — the eyes, ears and fingertips — of the machine’s control system that allow the designers to automate machine processes. Sensors have evolved considerably from the first non-contact controls that were developed to replace less-reliable electromechanical switches to accommodate increasingly advanced sensing applications."
And while the application may vary, there’s typically a sensor best-suited for the need. "When navigating automatic guided vehicles (AGVs), highly accurate and dependable sensors like laser scanners and encoders are the basis for attaining the high performance that AGV systems deliver," says Kenneth Palm, product manager, AGV systems, at Danaher Motion (www.danahermotion.com). With software, the information from these sensors is fused to provide a complete navigation solution, he explains.
"In order to control the speed of a vehicle, one needs a speedometer," explains Joseph Vu, applications engineer at Macro Sensors (www.macrosensors.com). "To control a robotic arm, we need a position sensor such as an LVDT to know where it is." With modern digital techniques, the LVDT can reach new heights in terms of temperature stability and accuracy, he says.
"By selecting the right type of sensor, the system designer can expect long-term system performance with continuous feedback," says Greg Montrose, sales manager, American Sensor Technologies (www.astsensors.com).
"Sensors play an ever-increasing role in machine control, especially as these processes become more and more complicated," says Robert Lee, sensors group marketing manager at Omron Electronics (www.omron.com). "For simple presence-absence detection, limit switches, photoelectrics and proximity sensors are more than adequate to fulfill the sensing solution. While photoelectrics are a very cost-effective solution for non-contact detection of targets from a distance, the different variations in photoelectric sensing still remain popular in solving many applications. In applications where the environment may affect the quality of sensing, besides using a limit switch, one may consider using proximity sensors as an alternative." Smart sensors combine the simplicity of photoelectric sensors with the complexity of vision sensors to detect difficult or intricate geometry, he adds.
"Sensors should be a forethought, not an afterthought," says Chris Graber, senior applications engineer, Banner Engineering (www.bannerengineering.com). "Too often, sensors are some of the last components specified during machine design, when in fact the efficiency of the entire machine control system depends upon sensing the product or process. Sensors, including photoelectric, ultrasonic and image, are key components that contribute to higher production throughput, less machine downtime and higher product yields through various error-proofing techniques."
Jim Ashford, president and COO of Omron STI (www. sti.com), agrees, even when it comes to safety sensors. "The best and least expensive way to incorporate safety into a machine is after a complete risk assessment and during the control design phase," he says. "That way, it's built into the machine, rather than being an afterthought."
Sensors are one of the key components to the efficient design of machine control, says Wayne Meyer, Sick industrial sensors product manager at Sick (www.sick.com). "Sensors give feedback about the product location, size, color or presence, using photoelectric, inductive, color, contrast and distance sensors," he explains. "In addition, sensors can be used during machine changeovers to speed up the automated adjustment of a machine. This is done by the remote setting of sensors, remote diagnostic retrieval and even something like a format adjustment drive which combines a motor with encoder to change position of guide rails when performing a changeover from one size product to another."
By including sensors in the machine architecture to provide vital data to the machine control system, real-time control and intervention become a reality, says Cees Links, CEO of Green Peak (www.greenpeak.com). "Wireless sensors can provide easy-to-install alternatives, especially when they have to be mounted on moving parts or in hazardous or hostile environments that would usually require an even more expensive type of cable," he says. "By using sensors equipped with ultra low power transceivers that require no battery replacement or that run on energy harvesting, the maintenance problem of replacing or recharging batteries can also be avoided."
Photoelectric sensors are becoming more and more important in automatic machines, says Carmine Clementelli, product manager, IDEC-Datasensor (www.idec-ds.com). "Sensors have become key factors as they control the machine functioning: object presence control, phase synchronization control and material quality control," says Clementelli. "Moreover, the sensors are fundamental for the productivity and reliability of an automatic machine functioning, for example, in the automatic format change during production without stopping the working cycle or the management of sensor functioning status information using auto-diagnostic functions in more advanced sensors."
Photoelectric sensors are robust, versatile, non-mechanical and have a relatively long life cycle, says Tim Kelley, vice president of business development and marketing at Tri-Tronics (www.ttco.com). "There are so many mechanical packages available in photoelectric sensors that the customers are not limited by the mounting configurations, size or packaging materials available in the market," he says.
|HOT, COLD, WET AND NASTY
E2EH inductive proximity sensors in a food-grade 316L stainless steel housing provide metal object or machine part detection in demanding environments. The sensor withstands temperatures up to 120 °C, resists corrosion from detergents used in the food industry and its performance has been tested and certified by EcoLab.
Omron Electronics LLC
|OPTICAL ANGLE SENSOR
OGL 55/54 optical angle sensor, an alternative to a proximity sensor, is designed for presence and part detection. These fork sensors align the transmitter and receiver in a fork like housing to guarantee sensor alignment. The sensor comes in metal or plastic housings and includes contamination detection via a LED that notifies users if oil, grease, dust or other contaminants are present.
ProSense line of pressure sensors and pressure switches now come with adjustable setpoints 0-5,800 psi, as well as transmitters in ranges from 0-15 to 0-3,000 psi with output options of 4-20 mA or 0-10 V. Transmitters with a measuring range of 0-10 in. of water column have also been added.
XUV ultrasonic sensor uses thru-beam technology to detect labels of any material, size, color or translucency. It detects labels between thicknesses of 0.03 mm (0.001 in.) and 0.08 mm (0.003 in.). The detection threshold of the sensor is adjusted using the +/- keys on the sensor. Rated IP65, the sensor has an operating range of 5 ºC to 55 ºC (41 ºF to 131 ºF).
Schneider Electric Sensor Competency Center
VisiSight sealed line of photoelectric sensors are available in the following models: diffuse models with 800-millimeter sensing range that provides adjustable sensitivity; polarized retro-reflective models with 3.5-meter sensing range in adjustable or fixed sensitivity versions; transmitted beam models that provide 10-meter sensing distance; and infrared LED source models for crosstalk immunity. All models include a red light to help with alignment and setup.
Rockwell Automation, Allen-Bradley
PSENslock secure safety gate system combines secure safety gate monitoring and a non-contact magnetic interlock in one unit. It is designed for applications up to SIL3 in accordance with EN/IEC 62061, Category 4 in accordance with EN 954-1 and protection type IP67.
Pilz Automation Safety L.P.
PD30 Series photoelectric sensors come in thru-beam, polarized retro-reflective, diffuse reflective, background suppression, retro-reflective and transparent object detection models. They include pushbutton programming, remote teaching options, mutual interference protection, sensor alignment aid and the ability to verify the sensor’s proper operation remotely via a PLC.
ECL202 eddy-current displacement/position sensor has an analog output that provides real-time displacement information up to 15 KHz with front panel and remote zeroing. The switch output threshold is user adjustable by front panel and remote control. User selectable bandwidth and DIN rail mount electronics provide application flexibility. Probes are available from 3 mm to 50 mm.
Series 14 photoelectric sensors are now available with a transparent rear housing section that allows the sensor’s interior to be observed, enabling viewing of operating and reception LEDs from practically every angle. This provides an advantage during sensor installation, adjustment and operation.
Simatic RF310R and RF380R read/write devices now accommodate both advanced and simple transponders (tags). These HF (high frequency) 13.56 MHz range devices have been redesigned with ISO 15693 functionality making them suitable for tags with little memory, including the MDS D100 and D124 ISO 15693 tags, as well as more sophisticated tags in the RF300 transponder range.
Siemens Energy & Automation
Series 45 pressure sensor prevents the overflow of tanks. Its remote digital readout lends itself to installation in flange outlets on storage tanks. Available in 2-to-12-in. flange mountings, the sensor can handle raw sewage, paper stock, oil, water, chemicals, etc.
|POSITION IN PLACE
GHSI 750 Series DC-operated position sensor is spring-wired and offers two-wire, loop powered 4-20 mA operation. Built-in loop powered electronics result in a position sensor that operates from a DC input and generates a pre-calibrated DC output that interfaces with many PLCs, digital indicators, A/D converters, computer-based data processors and QC data collection systems.
Ultrasonic sensor comes in a Q12 housing that achieves a 40 cm sensing range with a 2.5 cm blind zone. The small profile of the sensor allows it to be mounted in narrow spaces, like those found in packaging applications. The sensor is available with retro-reflective and diffuse operation modes.
IDEC-DATASENSOR SR21 photoelectric sensors have a 2 mm slot width, 12-bit resolution and 20 µsec response time. This means that users can consistently have labels fly through this sensor at a throughput speed of 25 kHz. That’s up to 25,000 labels/sec for detecting labels and color marks on packaging.
|WELD CAP SENSOR
WTS10 weld cap sensor checks the quality of welding cap fronts and detects faults such as inclusions, faulty dressing or burrs. It provides stability against discrepancies in the position and angle of the welding cap. The sensor checks upper and lower welding caps simultaneously and provides pre-fault indication for proactive maintenance.
|CUSTOM RESOLUTION ENCODERS
DFS 60 incremental encoders are available in fully programmable versions to accommodate any value from 1 to 65,536 pulses per revolution. With programming, users are able to select any number of lines between 1 and 65,536 via a PC or notebook. They are also able to set the zero pulse width to 90º, 180º or 270º and program the electrical interface to either HTL or TTL.
|SAFETY LIGHT CURTAINS
F3SJ safety light curtains are available in finger protection, hand protection or hand/limb body configurations. Sensors with protective heights of up to nearly 2.5 m are available for applications that involve large-sized workpieces.
Omron Scientific Technologies
MT miniature photoelectric sensors are designed specifically for machine applications that require a sensor as small as possible but in an industrial package that will withstand up to the environment. They are available in three sensing modes: polarized reflective, diffuse reflective and in a thru-beam model.
R-Series industrial sensor provides linear, absolute measurement and non-contact sensing technology in a variety of outputs such as SSI, DeviceNet, Profibus and EtherCat. With non-linearity less than 0.01% and repeatability within 0.001%, these sensors are suited for packaging applications. The electronics are double-shield for EMI immunity and available in IP67 or NEMA 4X housings for contamination protection and wash down.
U-Gage T30UX ultrasonic sensor for harsh environments has three ranges for sensing from 100 mm to 3 m and built-in temperature compensation. The housing is rated IP67 NEMA 6. A pushbutton teach-mode provides programming in applications such as clear bottle detection, automotive glass detection and color detection.
RS49 rotary sensor, designed for mobile and industrial applications, is a 0-5 V output, non-contact sensor that supports either single or dual outputs. It can measure rotary position or motion, and has a factory programmable angle of operation ±45°. Designed with a high-level of electromagnetic immunity, the sensor has over-voltage, reverse polarity protection and is RFI filtered.
Parker Hannifin, Electronic Controls Div.
GP500C communication controller chip is a low power transceiver-centric communications controller chip for wireless sensor networks. It is IEEE 802.15.4 compliant and allows developers to build sensor systems with a peak current of about 20 mA and a system sleep mode of below 100 nA.
|STAND UP TO CHEMICALS
E58 background rejection photoelectric sensors with a two-wire circuit design are resistant to chemical attack, moisture intrusion and can withstand heavy shock and vibration. Models are available with both ac and dc operation in a single unit and are available in 10 and 30 mm diameters. Visible sensing beam allows easy alignment.
LSS Navigator navigation sensors withstand temperatures from -30 ºC to +50 ºC and relative humidity less than 95% as well as mechanical stress like vibrations and shocks. It can be used indoors and outdoors for applications with automated guided vehicles.
HOBOnode family of research-grade, wireless sensors for outdoor environmental monitoring can transmit data to a PC several miles away without cables. Accompanying software displays real-time graphs of environmental conditions, and can provide alarm notifications via text messages and email when conditions exceed set thresholds.
Smarteye X-Pro Model XP10 sensors offer 10 µs response time. Designed for dual use as either precision registration-mark mode or photoelectric object-sensing mode, the sensors provide 5 µs repeatability, five memory locations, remote-control input line for PLC or external programming and a choice of 10 optical blocks.
RTD sensors operate over a temperature range of -200 ºC to 650 ºC (-328 ºF to 1202 ºF). They can be configured to meet specific application needs with options including element type, lead wire configurations, termination style, sheath materials, lengths and diameters, process connection heads, transmitters, thermowells, spring loading, flanges and surface mount packages.
|HIGH SPEED DATA COLLECTION
ADAM-5081 is a high-speed quadrature encoder and counter module for use with the ADAM-5550 series programmable automation controllers (PACs). It has a high isolation of 2,500 Vdc, a high speed frequency mode (5 Hz to 1 MHz) and a counter code at 1 MHz. There is also an advanced digital filter to eliminate noise and interference (1 to 65,000 μsec) which ensures accurate data collection and transmission.
Advantech, Industrial Automation Group
|CAPACITY TO ACCELERATE
Model 7290D variable capacitance accelerometer has onboard, microprocessor-based temperature compensation for high thermal stability for measurement of relatively low-level acceleration that requires measurement of whole body motion immediately after the accelerometer is subjected to a shock motion and the presence of severe vibration inputs. Gas damping and internal over-range stops enable its anisotropically etched, silicon sensing element to withstand high shock and acceleration loads.
GT all-in-one integrated contact sensor for height and thickness measurements requires no external PLC or external data processing. Designed for automatic in-line measurement, the IP67-rated GT has a linear ballbearing spindle tip that pneumatically extends and retracts for each measurement cycle. The ball-bearing tip eliminates wear and abrasion damage from contact with high-speed moving target surfaces.
Keyence of America
AST4100 OEM pressure sensor has 0.875-inch diameter and stainless steel header, and housing makes it suited for corrosive environments with pressure ranges 0-25 to 0-10,000 psi. Units are available in compound ranges, as well as in bar and Kg/cm2 outputs. Outputs include 10 mV/ V, 0.5-4.5 V ratiometric, 1-5 V, 1-6 V, 0.25-5 V or 4-20 mA.
American Sensor Technologies
|LINEAR MOTION ENCODER
AS5305 magnetic linear motion encoder IC is designed for linear motion and off-axis rotational measurement in industrial drives, x-y stages or electronic motors. A system-on-a-chip, combining Hall elements and a signal processor, has incremental measurement with a resolution to 14 μm per position step.
+43 (0)3 13 65 00 58 56
|HALL EFFECT SENSOR
Model 9360 non-contacting rotary, dual-output Hall effect sensor has 360° rotation and is suited for high-vibration environments. Electrical angle is 0-359.9°. Operating temperature is -40–85 ºC. Accuracy is ±0.6% FS. The sensor is ISO9001 and TSI6949 certified.
DigiPyro PYD 1988 and 1978 digital photoelectric infrared sensors for industrial motionsensing applications have window-detection sizes of 4.60x3.4 mm2 and 3x4 mm2, dual-element design, standard three-pin TO-5 metal housing, 15-bit output direct link and infrared window transmission. They have low EMI sensitivity and are RoHS-compliant.