laser sensors: alternative to conventional sensing · laser‐view technologies, inc. dba dimetix...

Laser‐View Technologies, Inc. dba DIMETIX USAStreet address: 205 Byers Road • Chester Springs, PA • 19425Mailing address: PO Box 195 • Lionville, PA • 19353Phone: 484‐212‐0636 • Fax: 206‐338‐4281 • E‐mail: [email protected]‐usa.com

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Laser Sensors: Alternative to

Conventional SensingPresented by: Steven LubeckPresident, Laser‐View Technologies, Inc. dba Dimetix USA


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Laser sensors as an alternative to conventional sensing

Laser distance sensor applications

(Distance sensors are not just for linear applications)

• Distance (absolute/relative)• Size (diameter, length, width)• Level• Orientation• Presence

Technologies compared based on performance, application specific, limitations, interfaces, and relative cost


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Laser sensors as an alternative to conventional sensing

• Hall effect sensors• Encoders• Proximity sensors• Potentiometers

• LVDTs• Eddy current• Ultrasonic• Barcode scanners

Laser sensors that monitor position in a non‐contact manner add value compared to conventional sensors Technologies compared to laser sensors in this discussion:


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Performance Comparison: SensorsSensor Range Environment Accuracy Sensitivity Cost Comparison

Hall Effect Short Standard On or off On or off Low• Target presence or absence• Magnetic interference

Encoders Long Standard Variable High Variable• Requires physical contact • Accuracy‐counts per revolution

Potentiometers Long Standard High High Low • Requires physical contact

LVDT/RVDT Limited Dirt tolerance High High High• Handles a high degree of power• Requires signal conditioning• Angular range of ±30°

Eddy‐Current Short Dirt tolerance Medium Variable Medium

• Noncontact• Material between sensor and target• Not high resolution• No large gap to target

Ultrasound Long Standard Variable High Variable• Noncontact• Clear/shiny target surfaces• Sensitive to temp/angle

Reflective Light Proximity

Long Standard Variable High Variable• Noncontact• Large gap to target OK• Accuracy determined by quality

Barcode Scanners Long Standard N/A N/A Variable• Susceptible to dirt/dust/damage• Depend on label for accuracy

Laser Sensors Long Dirt tolerance High High Variable• Noncontact• Large gap to target OK• Natural/high temp targets OK


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Hall Effect Sensors for distance measurement

● Varies its output voltage in reaction to a magnetic field

● Returns a voltage based on the presence, “on,” or absence, “off,” of a magnetic field

● Used for proximity switching, speed detection, positioning and current sensing applications

● Provides no scale for how far away an object is from the sensor

● Typically is effective for applications that do not require detailed position information.


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Hall Effect SensorsStrengths● Proximity switching, speed and

presence detection● Applications requiring only

general position information● Low cost

Cautions● Temperature● Hysteresis● “Noise” ‐ nearby steel/DC sources● Impact/shock – brittle magnets● Very limited range (inches max.)


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Laser Sensor Advantages vs. Hall Effect● Detailed discreet position

information● Long range capabilities


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Optical Encoders● Linear or rotary

● Can determine speed, direction, and position with fast, high accuracy

● Distance measured by light pulses, or “counts”

● The more counts (PPR), the higher the accuracy

● Variety output protocols:

● Analog

● Quadrature

● SSI (serial synchronous interface)


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Optical EncodersStrengths● Motion control● High resolution and accuracy

when properly mounted● Wide availability● Can be moderate priced● Linear and rotary configurationsCautions● Require some contact

– Friction and slippage– Sterile, high temp, delicate

● Seals required for foreign matter● Shock/vibration, high/low temps


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Laser Sensor Advantages over Encoders● Non contact

– Avoids friction and slippage– OK for sterile, high temp, delicate targets

● Robust – No mechanical parts– OK for dirty/dusty, low‐/high‐temperature environments when properly configured

● Cost effective for long distances


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Potentiometers● Use a sliding contact to create an

adjustable voltage divider that translates rotary or linear motion into a change in resistance

● Simple, compact

● Operate well in applications with modest duty cycles

● Are relatively cheap and can offer high accuracy

● Rotational position

● String potentiometers translate linear movement into rotary movement


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PotentiometersStrengths

● Relatively low cost and can offer high accuracy

● Simple, compact

Cautions

● Delicate ‐ susceptible to wear, vibration; foreign matter; temp

● Nonlinear

● Maintenance

● Provide a slight drag on the system

● String potentiometers are distance limited


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Laser Advantages over Potentiometers● Non contact

– Avoids friction and slippage– OK for sterile, high temp, delicate targets

● Robust – No mechanical parts– OK for dirty/dusty, low‐/high‐temperature environments

● More linear performance possible● Long range possible


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LVDTs and RVDTs● LVDTs (linear variable

differential transformers) are a type of electrical transformer used for measuring linear displacement (position)

● Rotary displacement counterpart is an RVDT

● Magnetic induction to determine position

● Known for both high precision and cost

● May require signal conditioning


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LVDTs and RVDTsStrengths

● High accuracy

● Reliable

● Robust, extreme environments

● Widely available

Cautions

● Typically more expensive

● Not compact

● Limited range

● Signal conditioning


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Laser Advantages over LVDTs and RVDTs

Strengths


● Detailed position information● Long range capabilities● Compact, lightweight


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Eddy‐Current Sensors● Use magnetic fields to determine

position and are moderately priced

● Only provide general position information

● Best used when mounted on a reasonably stationary mechanical structure to measure nearby moving machinery or products


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Eddy‐Current SensorsStrengths

● Surface defects

● Can detect through surface coatings

● Can be mounted/automated to measure machinery or products

Weaknesses

● Conductive materials only

● Very short range

● Not good for large, complex areas

● Susceptible to magnetic permeability changes (welds, etc.)


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Laser Advantages over Eddy‐Current● Detailed position information● Long range capabilities● Robust

– No mechanical parts– OK for dirty/dusty, low‐/high‐temperature environments

● Natural surface targets, including metals and semi‐opaque; target material is not a factor (plastic, metal, etc.)


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Ultrasonic Distance Sensors● Operate based on three physical

principles

– Time of flight– Doppler effect– Attenuation of sound waves

● Non‐contact

● Clear or shiny targets


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Ultrasonic Distance SensorsStrengths

● Liquid level, clear/reflective target surfaces

● Factory automation/process industries

● Moderate measuring ranges

Cautions

● Sensitive to temp, humidity, wind

● Target shape/angle/density

● Lower resolution vs. other sensors

● Cannot work in a vacuum


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Laser Advantages over Ultrasonic● Blind hole

– Ultrasonic typically for a large cone as the distance increases

● Interference with surrounding geometry


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Reflective Light Proximity Sensors● Detect presence or target

characteristics using properties of reflected light

● Good for “moderate range” applications

● Line of sight is required


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Reflective Light Proximity SensorsStrengths

● Quick response time

● Good for “moderate range” applications

● Sensing parts on a conveyor

Cautions


● Accuracy and quality of this sensor is related to its price

● Do not provide detailed position information (mainly presence)


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Laser Advantages over Proximity Sensors

● Real time distance measurements


● Excellent for long range applications

● Provide detailed position information



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Barcode Scanners● Scan barcode labels for position,

distance, product information

● ASRS, Distribution Centers, production lines

● Susceptible to dirt/dust/damage

● High temperature targets

● Depend on barcode label for accurate information


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Laser Advantages over Barcode ScannersStrengths

● Scan barcode labels for position, distance, product information

● ASRS, Distribution Centers, production lines

Cautions

● Susceptible to dirt/dust/damage

● High temperature targets

● Depend on barcode label for accurate information


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Laser Distance Sensors● Determine distance based on

triangulation, travel time, phase shift


● Excellent for both close range and long range

● Physical contact not required


● Accuracy and quality of the sensor is directly related to its price.


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Types of Laser Distance Sensors

• High accuracy

• Distances typically less than 48” (usually ‐6”)

• Cannot measure down tight holes

Triangulation

Reflected laser signal is processed via a CCD or CMOS chip. The spot at which the laser is detected on the chip is used to triangulate the distance measurement


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Types of Laser Distance Sensors

Time of flight• Fast response

• Long range

• Moderate accuracy

Time is measured between transmit laser pulse and the receipt of the reflected laser signal. Distance is calculated based on this time window.


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Types of Laser Distance SensorsPhase shift measurement• High accuracy

• Long range

• Moderate to fast response

Phasedetection

Distancecalcul ation

Phase shift of modulated signal is measured to determine distance


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Laser Distance SensorsStrengths


● Excellent for both close range and long range

● Physical contact not required

● Variety of outputs

Cautions

● Line of sight required (but we can measure through a series of bending mirrors)

● Accuracy and quality directly related to cost


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Measurement performance factors

Critical measurement factors

Factor Increased range / speed Decreased range / speed

Target surface Bright and reflective (See target plate accessory) Matte and dark surfaces

Airborne particles Clean air Dust, fog, heavy rainfall, heavy snowfall

Sunshine Darkness Bright sunshine on the target


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Laser safety classifications

Lasers are classified as an electronic product that emits radiation and, for regulatory purposes, require an FDA Accession number to be legally marketed in the United States.Many laser pointers, as an example, do not have FDA accession numbers and could potentially represent an eye safety hazard.


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Accuracy – at what standard deviation?

The typical accuracy at 2σ:

±1 mm for the FLS‐C(H) 10

±1.5 mm for the DLS‐C(H) 15

±3.0 mm for the DLS‐C(H) 30 / FLS‐C(H) 30

Note the standard deviation at which a laser sensor’s accuracy is specified


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Sensor/controls CompatibilityCommon interfaces for laser sensors:

• Analog current 4‐20mA• Profibus• SSI encoder• Ethernet IP• RS232/422 serial

Interface with popular PLC platforms:

• Rockwell Automation• Siemens• Unitronics

PLC / IPCAnalog

SSI EncoderEthernet IPRS 232RS 422etc

I/OsI/OsI/OsI/Os

Digital inputs

Digital outputs

Analog inputs

Analog outputs

SSI

Laser sensorLaser sensor

Modular I/O SystemModular I/O System

Central controller unitCentral controller unit

Analog

SSI Encoder

RS 422

RS 232

EthernetGatewayEthernetGateway

Ethernet/IP

PLCPLCLaser sensorLaser sensor


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Laser Sensor Application Examples


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Metals Industries


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Application Examples

Industry: Steel ProductionApplication: Transfer Car PositionSensor: Dimetix DLS / FLS LaserDescription:• Position transfer car between heat treat

lines and furnaces• Cooled laser enclosures for high temp • Integrated with displays and communicates

with PLC networkWhy laser?• Replaces floor mounted limit switches that

caused downtime once a month typically• Holds up to dirt, grease, physical abuse

.

Steel Production Transfer Car Position


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Application ExamplesSteel Production Transfer Car Position


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Industry: Steel Production

Application: Coil Diameter on Slitter Machine

Sensor: Dimetix FLS Laser

Description:

• Measure coil diameter during slitting process

• Measure to bright steel

• Rugged and non‐contact‐ holds up to hostile machining environment

Why laser?

• Rugged and non‐contact‐ holds up to hostile machining environment

• Accurate long range measurement

• Can be mounted far away safe from damage and not in the way of operators or equipment

Steel Production Coil Diameter


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Application: Zinc Pot Level

Sensor: Dimetix DLS / FLS Laser

Description:

• Measure level in zinc pot

• Insulated and cooled enclosure for high temp operation

• Radiation shield applied to face of enclosure

Why laser?

• Rugged and non‐contact‐ holds up to hostile steel mill environment

• Contact sensors not possible due to temperature of material to be measured

Steel Production Zinc Pot Level


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Application: Slab Width on caster line


Description:

• Measure width on caster line using a pair of Dimetix sensors in differential thickness mode

• Applications specific rugged cooled enclosure

• Window air purges for cleaning lens of scale an debris

Why laser?

• Measure to target without contact

• Accurate lo range measurement

• Rugged and can be mounted out of harms way

Steel Production Slab Width


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Industry: Steel, Lumber, FabricationApplication: Saw Blade Alignment

Sensor: Dimetix DLS Laser

Description:

• Pair of laser sensors monitor distance to saw blade during alignment

• Special fixture

• Application specific controller displays and zeroes lasers relative to saw bed

Why laser?

• Long range

• Accuracy

• Ruggedness/non‐contact

Saw Blade AlignmentGantry Plate Saw in a Fabrication Environment


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Industry: Metal Production & Fabrication

Application: Laser Controlled Cut‐Off Solution


Description:

• Laser is zeroed on saw blade and measures the material cut length

Why laser?

• Long range‐c an be mounted faraway to clear material

• Accuracy

• Non‐contact

Metal Production & FabricationLaser Controlled Cut‐Off Solution

Cut‐off system monitor controls cut length and adjusts feed rate as target approaches desired length.

Behringer saw controlled by cut‐off system.Dimetix laser and protective housing.


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Components

Dimetix FLS‐C10 laser distance sensor

Monitor interface with integrated PLC controller

Housings, cables and connections

Adjustable, heavy duty steel mounting bracket

Benefits

Flexible installation, versatile application

High accuracy, low maintenance and cost

Compact IP65‐rated package

Non‐contact, eye‐safe laser measurement

Quality and efficiency improvements

Application ExamplesMetal Production & FabricationLaser Controlled Cut‐Off Solution


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Application: Coke Machine Door Presence

Sensor: Dimetix FLS‐CH10 Laser

Description:

• Spotting and positioning coke door machines at Burns Harbor Steel Mill.

Why laser?

• Accuracy

• Non‐contact

• Can be integrated with heater and can measure through glass on an enclosure to deal with harsh environment

Steel Production Coke Door Machine



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Application: Coke Oven Charging

Sensor: Dimetix FLS‐C10 laser

Description:

• Ensure coke ovens are fully charged and production is not being lost due to undercharging.

• Lasers are installed behind cooled viewing port

Why laser?

• Ability to discriminate reflective intensity

• Non‐contact

• Rugged

Steel Production Coke Oven Charging



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Paper Production


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Industry: Paper & Textile

Application: Roll Diameter and Width Monitoring

Sensor: Dimetix DLS and FLS Laser

Description:

• Three (3) lasers measure diameter and width

•Measure diameter from above

•Measure width with a pair of laser sensors in differential mode

Why laser?

• Accuracy

• Non‐contact

• Long range permits out‐of‐the‐way mounting without sacrificing accuracy

Paper & Textile MillAutomated Diameter & Width Measurement


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Hazardous Environments


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Hazardous Environment:Explosion Proof Container

NEMA 4X standard for outdoor / washdownapplications

Dual‐sided instrument enclosure keeps power supply and laser in separate chambers

Maintains certification while machining wall between chambers

Approvals, Compliances, & Certifications

• Approvals: UL, CSA (Canada), and FM Atex

• Compliances: NEC Class 1, Div 1&2 (Groups B,C, &D), Class II, Div 1&2 (Groups E,F, &G); NEMA 7&9 (Optional 3, 4X), Atex

• Certifications: Atex certificate number: FM09ATEX0073U


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Materials Handling: Crane monitoring


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Application ExamplesMaterials Handling Crane Collision MonitoringIndustry: Materials Handling

Application: Crane Collision Monitoring

Description:

Position and collision monitoring system for an overhead crane at an auto manufacturing facility.

Why laser?

• Accuracy

• Non‐contact

• Long range

• Absolute output


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Materials Handling:

Collision Monitoring System Components Typical Installation


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Application ExamplesEND STOP LIMITS RESTRICTED ZONE RESTRICTED AREAS AUTO POSITIONING


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Transportation of Viscous Materials


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Application ExamplesViscous Bulk MaterialsLaser Level Monitoring in aPiston TruckIndustry: Transportation of Viscous Bulk Materials

Application: Non‐Contact Piston Location Monitoring on a Piston TankerSensor: Dimetix DLS‐CH30 Laser

Description:• The DLS‐CH30 laser monitors the position of the internal piston as the tank is filled or the tanks contents

are pumped out under pressure; Implemented (1) DLS‐CH30 laser and a pair of displays (1 front, 1 rear)Why laser?• Long range• Ruggedness• Ability to laser and measure through glass


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Level Measurement


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Industry: Plastic Molding, Food Processing, and Construction Materials

Application: Silo Level Measurement

Sensor: Dimetix EDS, DLS, & FLS Laser

Description:

• Measure bulk material levels in bins, hoppers, or silos

• Benefit is to accurately manage inventory and to minimize production delays

Why laser?

• Measurement range

• Ability to measure n semi‐transparent material

• Non‐contact and rugged

Silo Level Measurement Technologies



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Industry: Glass Manufacturing

Application: Non‐Standard Pallet Height Measurements

Sensor: Dimetix EDS, DLS, & FLS Laser

Description:

• The Conveyor apparatus after picking up the glass was unable to compensate for non‐standard height of the pallets used to transport and store the glass panels in a horizontal position

• The Dimetix laser distance sensor measures the height of the pallet and adjusts a position offset to stop the glass panel and begin tilting it onto the pallet precisely

Why laser?

• Accuracy

• Range

• Interfacing capabilities

Laser Measurement Solution Prevents Damage to Glass Panels During Production



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Hydrodynamic Power Station


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Industry: Hydrodynamic Power Station/Flood Control

Application: Flood Gate Position Monitoring


Description:

• Reliably and accurately monitoring flood gate height remains an ongoing challenge

• In this example (20) FLS lasers were installed to measure flood gate positions

Why laser?

• Range

• Enclosure addressed maintenance issues and account for exposure to weather, dust, airborne, particles, and other environmental factors

Hydropower/Flood ControlApplication Examples


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Industry: Engineering and Construction

Application: Flood Gate Position Monitoring System


Description:

• Flood gate position monitoring system; measured actual height of gate stem in gate house under a roadway

Why laser?

• Need to measure though enclosed glass housing

• Cold temp operation

• Measurement range with limited overhead size limitation

Flood Gate Position, NY StateApplication Examples


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Engineering and Construction


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Application: Bridge Structural Monitoring


Description:

• Historic Bridge widening project in New Orleans

• Two steel bridge trusses measuring 528 feet in length and weighing 2,700 tons, were built on shore, and simultaneously lifted 130 feet and set in place on the bridge

• The project required a real‐time, remote monitoring system to measure truss distortions and to eliminate overstressing or buckling of the truss during the transport, lift, and setting operation.

• A total of (10) DLS laser distance sensors (5) on each truss were used

Bridge Structural MonitoringApplication Examples


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Application:Monitoring Expansion Joint Gaps


Description:

• Monitor expansion joint gaps

• (4) FLS laser distance sensors were used as displacement sensors installed under the bridge deck far enough from the expansion joint, where they can be protected from the weather and salt debris to prevent damage to the window

Why laser?

• Ability to measure through glass

• Accuracy / measurement stability under extreme conditions

Bridge Project in New York CityApplication Examples


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Structural Health MonitoringApplication Examples


Application: Multi‐sensor/multi‐axis Structural Monitoring


Description: Long‐term study of (2) piers on a Western PA bridge monitored for movement under load on (3) axes

• Approximately 60 feet between piers

• Each system contained (3) Dimetix FLS‐C10 lasers, mounted in a sealed windowed enclosure and aimed at target plates mounted on a common rail

– Target 1: 45 degree vertical (Z axis)

– Target 2: Perpendicular (X axis)

– Target 3: 45 degree horizontal (Y axis)

• Lasers daisy chained and connected via RS422 to a Campbell Scientific remote data monitoring system

Why laser?

• Accuracy at long range

• Accuracy / measurement stability under extreme conditions


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Application: Structural Health Monitoring


Description:

• Multi‐Sensor Structural Health Monitoring System

• Structural health monitoring system to ensure no shift of the existing bridge structure

• Implemented (3) FLS lasers and a specialized high precision 2‐dimensional laser position target detector

• Measured transversal displacement from the bridge piers to the sports arena

• Detectors measured transversal and vertical displacement

Why laser?

• Accuracy at long range

• Stability of measurement

• Tight laser spot size

Structural Health MonitoringApplication Examples


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Related companies & brands:

Thank you for your attention

Presented by: Steven LubeckPresident, Laser‐View Technologies, dba Dimetix USA

Tel: 610‐497‐8910Email: slubeck@dimetix‐usa.comWeb: www.dimetix‐usa.com

www.laser‐view.com

Presenter contact information:

laser sensors: alternative to conventional sensing · laser‐view technologies, inc. dba dimetix...

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