IN THE NAME OF GODIN THE NAME OF GOD

Instrumentation Term ProjectInstrumentation Term Project

Supervised By: Dr. Supervised By: Dr. HamidHamid D. TaghiradD. Taghirad

Magnetic position sensor

Ehsan PeymaniGolnaz Habibi

Magnetic Sensor

Feature of Magnetic Sensors

Advantage- Contact less- Unaffected by Contamination

Disadvantage- affected by other magnetic field

Position sensing ( all types )

CapacitiveEddy currentOpticalInductiveResistiveSonarLaserMagnetic

All Types of Magnetic Position Sensor

Hall effect sensorMagnetostrictiveMagnetoresistiveBase on Seismic theory Reed switchSynchro & ResolverInductosynMagnesynMagnetic encoderLVDT & RVDT

Special application

CompassingGPS navigationVehicle detection

Special applicationCompassing

Special application Compassing

Special application Compassing

Special applicationGPS navigation

Special applicationGPS navigation

Special applicationVehicle detection

Special applicationVehicle detection

Special applicationVehicle direction

Smart position sensor

Smart position sensor

Specifications :

Magnetostrictive LDTSmall & InexpensiveLinearity+/- 0.05% of StrokeAccuracy+/- 0.1% of StrokeRepeatability+/- 0.01% of full strokeOperating Temperature-20° to 70° C Programmable

Hall Effect Sensor

Hall effect : Dr. Edvin Hall , 1879Johns Hopkins University

Hall sensor : Joe Maupin & EverttVorthmann , 1965

Hall effectGeneral features

• True solid state• Long life • High speed operation - over 100 kHz

possible• Operates with stationary input (zero speed)• No moving parts• Logic compatible input and output• Broad temperature range (-40 to +150°C)• Highly repeatable operation

Hall effectTheory

Hall effect

Theory

tBIKV H

H =

Hall effect

Theory

Hall effectConditional Circuit

GVVS µ7=

!!! Silicon exhibits the piezoresistance effect

Hall effectConditional Circuit

Hall effectDigital Hall sensors

Hall effectAnalog Hall sensors

Hall effectMagnetic system

Unipolar head-on modeUnipolar slide-by modeBipolar slide-by modeBipolar slide-by mode (ring magnet)

Jump to Application

Hall effectMagnetic system

Unipolar head-on modeNonlinearAccuracy medium

Hall effectMagnetic system

Unipolar slide-by modeNonlinearAccuracy lowSymmetric

Hall effectMagnetic system

Bipolar slide-by modeAccuracy mediumDissymmetry

Hall effectMagnetic system

Hall effectMagnetic system

Bipolar slide-by mode (ring magnet)

Hall effectMagnetic system comparison chart

Hall effectApplication – Vane operated position sensors

Hall effectApplication – Vane operated position sensors

Hall effectApplication – Other in position

Sequence sensorProximity sensorOffice machine sensorsMultiple position sensorAnti-skid sensorPiston detection sensor

Hall effectApplication – Sequence sensor

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Hall effectApplication – Proximity sensor

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Hall effectApplication – Office machine sensors

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Hall effectApplication – Multiple position sensor

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Hall effectApplication – Anti-skid sensor

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Hall effectApplication – Piston detection sensor

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Magnetostrictive sensors

Invent at 1970 MTS Temposonictechnology

Theory of Magnetostrictive sensors

Manetostrictive effectVillari effectWiedemann effect

Theory of Magnetostrictive sensorsManetostrictive effect

Theory of Magnetostrictive sensorsVillari effect

Reverse of Magnetoestrictive

applying stress to a magnetostrictive material

changes its magnetic properties

Theory of Magnetostrictive sensorsWiedemann effect

Theory of Magnetostrictive sensorsThe operation

Theory of Magnetostrictive sensorsThe operation

Magnetostriction sensorsFeatures

Non contactAbsolute10 mm ~ 20 mNonlinearity < 0.02%

Magnetostriction sensorsComparison

Magnetostriction sensorsApplication

1. Automated (Robotic) ManualTrans ission2. Automotive Suspensions3. Automotive Steering4. Medical Hospital and Home Care Bed5. Medical Infusion Pump6. Medical Dental Chairs7. Tractor Steering8. Commercial Appliance Damping9. Automotive Tank Levels10. Construction Equipment

Magnetostriction sensorsApplication – Automated (Robotic) ManualTrans ission

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Magnetostriction sensorsApplication - Automotive Suspensions

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Magnetostriction sensorsApplication - Automotive Steering

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Magnetostriction sensors

Application - Medical Hospital and Home Care Bed

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Magnetostriction sensorsApplication - Medical Infusion Pump

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Magnetostriction sensorsApplication - Medical Dental Chairs

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Magnetostriction sensorsApplication - Tractor Steering

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Magnetostriction sensorsApplication - Commercial Appliance Damping

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Magnetostriction sensors

Application - Construction Equipment

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Magnetostriction sensorsApplication - Automotive Tank Levels

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Magnetoresistive sensors

Invent at 1856William ThompsonLord Kelvin

Magnetoresistive sensorsAll types

Anisotropic Magnetoresistive (AMR)

Giant Magnetoresistive (GMR)

Colossal Magnetoresistance (CMR)

Magnetoresistive sensorsTheory of AMR

Magnetoresistive sensorsTheory of AMR

θ2cos

Barber Pole Bias

Magnetoresistive sensorsTheory of AMR

Magnetoresistive sensorsOperation of AMR

Magnetoresistive sensorsOperation of AMR (HMC1501)

Magnetoresistive sensorsOperation of AMR (HMC1501)

Magnetoresistive sensorsOperation of AMR (HMC1501)

Magnetoresistive sensorsOperation of AMR (HMC1512)

Magnetoresistive sensorsOperation of AMR (HMC1512)

Magnetoresistive sensorsOperation of AMR (HMC1512)

Magnetoresistive sensorsOperation of AMR (HMC1512)

Magnetoresistive sensorsTypical application

Cylinder position sensing in pneumatic cylinders Elevator sensor Lid sensor for laptop computers Position sensor for materials handling equipment (lift trucks) Blood analyzer Magnetic encoders

Magnetoresistive sensors

Comparision of Hall effect & MR technologies

Magnetoresistive sensorsGiant Magnetoresistive (GMR)

Observe at 1988Magnetoresistivity > 70%

Magnetoresistive sensorsGiant Magnetoresistive (GMR) - Theory

Magnetoresistive sensorsGiant Magnetoresistive (GMR) - Application

Proximity DetectionDisplacement SensingRotational Reference Detection

Colossal Magnetoresistive (CMR)

Observe at 1988Magnetoresistivity > 1000% ~ 10000000%

Magnetoresistive sensorsComparison

Reed switch

Reed switchStructure

Reed switchAdvantages

Long lifeSmall sizeVery sensitive to magnetic fieldsHas no leakage current or voltage dropVery inexpensiveHighly repeatable operation High immunity to dirt and contaminationZero power consumption

It is electronically noisySlow response timeLarge amount of hysteresis

Reed switchDisadvantages

Synchro & Resolver

A device called Selsyn was developed at 1925

SynchroTheory

Synchro is variable rotary transformer.

SynchroClassification

Transmitter

ControlTorque

SynchroClassification

Receiver

ControlTorque

SynchroClassification

Differential Transmitter

ControlTorque

SynchroClassification

ControlTorque

SynchroAdvantages

The controlling unit can be along distance from the controlled unit.Low consumption.Eliminates the necessity of mechanical linkage.Continues accurate and visual information.Good reliability and minimum maintenances .Small and light.Very fast.

Resolver

ResolverTheory

Signal Conditioning

Resolver-To-Digital Converter(RTD /RDC)BasicUndersamplingOversampling

RTDBasic

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RTDUndersampling

RTDUndersampling

RTDOversampling

OversamplingTMS320F240

ResolverAdvantages

Accurate Absolute Position SensorSmall sizeWell-suited to severe industrial environmentsNot require ohmic contact.High reliability

Synchro& ResolverApplication

Naval weaponsRadar antennasAerospaceRobotics

Inductosyns

Inductosyns types

Linear inductosynRotary inductosyn

Linear inductosyns

inductosynsSpecification

Use RTD for signal conditioningLinear resolution is 5microinch.angular resolution is less than 0.9 arc secondsrelatively expensivevery high accuratevery reliable

inductosynsAdvantages & Disadvantages

AccurateSmall sizeWell-suited to severe industrial environmentsNot require ohmic contactHigh reliability but relatively expensive

Magnesyn

MagnesynStructure

Magnetic encoderAll types

LVDT & RVDT

End of World War II

Linear Variable Differential Transformer(LVDT)

PRECISION ABSOLUTE VALUE CIRCUIT(FULL-WAVE RECTIFIER)

LVDT & RVDTComparison

LVDTMeasurement ranges are ±100µm to ±25cmSensitivity is 2.4mv per volt per degree of rotationInput voltages are from 1V to 24V RMS, with frequencies 50Hz-0kHz

RVDTTypical RVDTs are linear over a range of about ±40ºSensitivity is 2 to 3mV per volt per degree of rotationInput voltages in the range of 3V RMS at frequencies between 400Hz and 20kHz.

Advantages

Infinite ResolutionHigh accuracy and sensitivityExcellent linearity ( 0.5%)A wide variety of measurement ranges

LVDT

Application

Modern Machine-toolRoboticsAvionics & aircraftProcess control industryTorpedo, and weapons systems.

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