electronics, sensor and signal processing.pdf

electronics, sensor and signal processing

1. Introduction to Mechatronics Introduction to Mechatronics
Department of mechanical engineering
College of engineering
Debre Berhan University
C.By Samueal T. ,2023 C.By Samueal T. ,2023

2. 01 01
Introduction to Electronics,
sensors and actuators

3. Outline
✓What is Electronics in Mechatronics system ?
✓What is sensor ?
✓What is the function of sensors and signal
conditioning?
✓What is actuators and its function?

4. Basic Electrical Elements
Thethreebasicpassiveelectricalelements:
➢Theresistor(R),Capacitor(C),andinductor(L).
Therearetwotypesofidealenergysource:
➢Avoltagesource(v)andacurrentsource(I).
➢Theseidealsourcescontainnointernalresistance,inductanceor
capacitance.
Schematic
symbolsforbasic
electricalsystems

5. Cont.
Resistors
Voltage source
Capacitors
Inductors
Examples of basic circuit elements

6. Resistor
Aresistorisadissipativeelementthatconvertselectricalenergy
intoheat.
Ohm’slawdefinesanidealresistor:V=IR,unitohm().
Conductanceisthereciprocalofresistance.Itissometimes
usedasanalternativetoresistancetocharacterizea
dissipativecircuitelement.

7. Capacitor
Acapacitorisapassiveelementthatstoresenergyintheformof
anelectricfield.
Capacitorconsistsofapairofparallelconductingplatesseparated
byadielectricmaterial.
Thedielectricmaterialisaninsulatorthatincreasesthecapacitance
asaresultofpermanentorinducedelectricdipolesinthematerial.
Cisthecapacitance
measuredinfarads
(F=coulombs/volts).
I(t)=??????
????????????
????????????

8. Inductor
Aninductorisapassiveenergystorageelementthatstoresenergy
intheformofamagneticfield.
Thesimplestformofaninductorisawirecoil,whichhasa
tendencytomaintainamagneticfieldonceestablished.
Theinductor’scharacteristicsareadirectresultoffaraday’slawof
induction.Whichstates
V(t)=
??????
????????????
Whereisthetotalmagneticfluxthrough
thecoilwindingsduetothecurrent.

9. Semi conductor devices
Electronicmaterialsareclassifiedinto
threetype
1.Conductors
➢Conductorshavelowresistance
whichallowselectricalcurrentflow.
➢Plentyoffreeelectronsfloating
➢Theatomicstructureofgood
conductorsusuallyhaveoneelectron
intheiroutershell.
➢Cu,Ag,Au,Al,Ni,

10. Cont.
2.Insulators:havehighresistance
whichsuppresseselectricalcurrent
flow.
Veryfeworno“freeelectrons”
floating.
Mostinsulatorsarecompoundof
severalelements
➢Glass,ceramic,plasticsandwood.
Theatomsaretightlyboundtoone
anothersoelectronsaredifficultto
stripawayforcurrentflow.

11. Semiconductor
➢Semiconductorsarematerialsthat
essentiallycanbeconditionedtoact
asgoodconductorsorgood
insulators,oranythinginbetween.
➢semiconductorelementhasfour
electronsinitsouterorvalenceorbit
➢Commonelementssuchascarbon,
silicon,andgermaniumaresemi
conductors.
➢Siliconisthebestandmostwidelyusedsemiconductors

12. silicon
Ithasfourvalenceelectronsinitsoutermostshell.Whichshares
withitsneighboringsiliconatomstoformfullorbital’sofeight
electrons.
Theuniquecapabilityofsemiconductoratomsistheirabilityto
linktogethertoformaphysicalstructurecalledacrystallattice.

13. Semiconductors can be insulators
❑Ifthematerialispuresemiconductormateriallikesilicon,the
crystallatticestructureformsanexcellentinsulatorsinceallthe
atomsareboundtooneanotherandarenotfreeforcurrentflow.
❑Goodinsulatingsemiconductormaterialisreferredtoas
intrinsic.
❑Sincetheoutervalenceelectronsofeachatomaretightlybound
togetherwithoneanother,theelectronsaredifficulttodislodge
forcurrentflow.
❑Theabilityconductimprovedbyreplacingoraddingcertain
donororacceptoratomstothiscrystallinstructure.“Doping”.
❑Diodeisasemiconductordevicethatallowsanonwayswitch
forcurrent.

14. semiconductors can be conductors
❑Tomakethesemiconductorconduct
electricityotheratomscalledimpuritiesmust
beadded.
❑Ex.Addingarsenic,whichhas5valence
electrons,willallowfourofthearsenic
valenceelectronstobondwiththe
neighboringsiliconatoms.
❑Theoneelectronleftoverforeacharsenic
atombecomesavailabletoconductcurrent
flow.
❑Bycontrollingthedopingofsiliconthesemiconductormaterialcan
bemadeasconductiveasdesired.

15. cont.
➢Dopingasemiconductormaterialwith
anatomsuchasboronthathasonly3
valenceelectrons.
➢The3electronsintheouterorbitdo
formcovalentbondwithits
neighboringsemiconductoratomsas
before.
➢Theholeassumesapositivechargesoitcanattract
electronsfromsomeothersource.

16. Types of semiconductor materials
➢Thesilicondopedwithextraelectronsiscalledan“Ntype”
semiconductor.
“N”isfornegative,whichisthechangeofanelectron.
➢Silicondopedwithmaterialmissingelectronsthatproduce
locationscalledholesiscalled“Ptype”semiconductor.
“P”isforpositive,whichisthechargeofahole.

17. Cont.
N-type semiconductors doped with donor elements (e.g. arsenic or
phosphor group V elements ) that results in one additional electron
freed (free electron) from the crystal lattice as a charge carrier that
is available for conducting.
P-type semiconductors doped with acceptor elements (e.g. boron or
gallium group III elements) that results in a missing electron in the
lattice structure, which is called a hole.

18. N-type semi conductor
Introduce an impurity atoms such
phosphorus in to the crystallin structure.
These atoms have five outer electrons
leaving one “ free electron” “ donors”
An N-type semiconductor material has
extra electrons.
➢current (electrons) flow from the
positive terminal to the negative
terminal.

19. P-type semiconductor
Aluminum,Boronhavethreevalence
electronswhenitdoppedwithsiliconthe
fourthclosedbondcannotbeformed.It
createpositivelychargedcarriesknownas
holes.
Movementofholesresultsinashortageof
electrons“Acceptors”
Current(electronsflowsfromthepostive
terminaltothepositiveterminal.)
Ap-typesemiconductormaterialhasa
shortageofelectronswithvacanciescalled
holes.

20. PNjunction
When an N –type material is fused together with a p-typematerial
free electrons from the donor begin to migrate across the junction
to fill up the holes in the P-type material.
Electronicsymbol..PNjunction

21. cont.
PtypeandNtypesemiconductors,takenseparatelyareofvery
limiteduse.WhilePNjunctioncanfunctionas:
➢Rectifier
➢Amplifier
➢Switchingandotheroperationsinelectroniccircuits.
InPNjunctiondiode,NisatrightandPisatleft
Majoritycarriers
➢N-region–electrons
➢P-region–holes

22. cont.
PNjunction can basically work in two modes,
Forward bias mode : positive terminal connected to ‘P’ region and
negative terminal connected to ‘n’ region
Reverse bias mode : negative terminal connected to ‘p’-region and
positive terminal connected to ‘n’-region .

23. Diode
A diode is a two-terminal electronic device that is constructed by
joining a p-type and an n-type semiconductors together to form a
pnjunction.
The terminal associated with the p-type material is called the
anode, and the terminal associated with the n-type material is called
the cathode.

24. Forward biased PNjunction
Negative voltage is applied to the N-typematerial, positive voltage
is applied to the P-typematerial.
It forces the majority charge carriers to move across the junction…
decreasing the width of the depletion layer.

25. Rectifiers
➢A pnjunction passes current in only one direction. It is known
as a silicon diode and sometimes referred to as a rectifier.
➢Rectifiers is a diode it Convert an alternating voltage (AC)
into a continuous voltage (DC) by using one or more P-N
junction diodes.
➢The reverse operation is performed by an inverter.
➢A diode behaves as a one-way valve that allows current to flow
in a single direction.
➢Adiode is used as a switch, and a rectifieris used to the
conversion.
➢Rectifier are two basic types;
➢Full wave and
➢Half wave

26. Half wave rectification
➢Itisthesimplestofalltherectifiercircuits.
➢Itusedforconvertingtheone-halfcycleofACinputtoDC
output.
➢Theoutputvoltageisunidirectionalintermittentandvarying
voltage.
➢Ahalf–waverectifierscircuitusesonlyonediodethatallows
onlyone-halfcycleofanACvoltagewaveformtopasswhile
blockingtheotherhalfcycle.

27. Full wave rectifier
➢Afullrectifierisdefinedasarectifierthatconvertsthe
completecycleofalternatingcurrentintopulsatingDC.
➢Theoutputvoltageisunidirectionalvaryingvoltage.

28. Reverse biased pnjunction
➢Ifthe+veofthebatteryisconnectedtothen-typeandthe–ve
terminaltotheP-type.
➢Thefreeelectronsandfreeholesareattractedbacktowardsthe
battery,hencebackfromthedepletionlayer,hencethe
depletionlayergrows.
➢Thusareversebiasedpnjunctiondoesnotconductcurrent.

29. Transistors
A transistor is a semiconductor device that has three or more
terminalsand can provide power amplification and switching.
➢Power amplification by modulating a relatively large current
between or voltage across two terminals using a small control
current or voltage.
➢Switching by effectively opening and closing the connection
between two terminals using a controlled signal on the third
terminal.

30. NPN and PNP transistor
Transistor act as a switch which can open and close many times per
second . They have three leads
The base-which is the lead responsible for activating the transistor .
It is the gate controller device
The collector-which is the positive lead and electrical supply
The emitter-which is the negative lead and the outlet for the supply
The transistor PNP and NPN are the basic electrical components,
used in various electrical and electronic circuits to build the projects.

31. Cont.
The operation of the PNP and NPN transistors
mainly utilizes holes and electrons.
In PNP transistors, the majority charge carriers
are holes, where
In NPN the majority charge carriers are
electrons.

32. PNP transistor
PNP stands forpositive, negative, positive and also known as
sourcing.
The majority charge carriers are holes
The required materials used to build the emitter (E), base (B) and
collector (C) terminals in this transistor are diverse from those used
in the NPN transistor

33. NPN transistor
➢NPN transistors serve as amplifiers, switches
➢NPN transistor carriers (electrons) though the base region that
constitutes transistor action, since these mobile electrons
provide the link between the collector and emitter circuits.

34. Cont.
PNP and NPN transistor

35. Cont.
EmittertoBaseshouldactlikea
normaldiodeandconductoneway
only
Collector-basejunctionshouldact
likeanormaldiodeandconduct
onewayonly
Emitter-collectorshouldnot
conductineitherdirection

36. Optoelectronic diodes
Also called light-emitting diodes (LED) which emits photons
when forward biased.
●The LED is usually encased in a colored plastic material
that enhances the wavelength generated by the diode and
sometimes helps focus the light into a beam.
Theintensityoflightisrelatedto
theamountofcurrentflowing
throughthedevice.

37. sensors and transducer
❑Sensorsisadevicethatproducesanoutputsignalforthe
purposeofsensingofaphysicalphenomenon.
Itisusedforaninputdevicethatprovidesasausableoutputin
responsetoaspecifiedphysicalinput.
Forexample,athermocoupleisasensorthatconvertsa
temperaturedifferenceintoanelectricaloutput.
❑Transducerisadevicethatconvertsasignalfromoneformof
energyintoanotherformofenergy.

38. cont.
Transduceradevicethatconvertsonetypeofenergytoanother
energytypes.
Examplelight,chemical,acousticorthermalenergyinto
electrical,ormechanical,orelectromagneticenergy.
e.g.Amotorconvertandelectricalinputintomechanicalrotation.

39. cont.
Typicalvariablesthatneededtobemeasuredinadataacquisition
andcontrolsystemsare;
1.Displacement,Position,velocity,acceleration
2.Force,torque,strain,pressure
3.temperature
4.Flowrate
5.Humidity
Asensorsisplacedintheenvironmentwhereavariablesisto
measured.

40. cont.
therearethreebasicphenomenonineffectinanysenoroperation,
1.Themeasuredphysicalvariables(i.e.pressure,temperature,
displacement)istranslatedintoachangeintheproperty
(resistance,capacitance,magneticcoupling)ofthesensors.
thisiscalledtransduction.
2.Thechangeinthepropertyofthesensorsistranslatedintoa
low-power-levelelectricalsignalintheformofvoltageor
current.
3.Thislow-powersensorssignalisamplified,conditioned,and
transmittedtoanintelligentdeviceforprocessing.i.e.display
oruseinaclosedloopcontrolalgorithm.

41. sensors
1.Displacement,positionandproximitysensors
Displacementsensor:-areonesthatprovidesinformationabout
thechangeinthepositionofarigidbody,
❑Howmuchtheobjecthasbeenmoved.
Positionsensors:-isusedforasensorthatgivesameasureofthe
distancebetweenareferencepointandthecurrentlocationofthe
target.
❑Positionofanobjectwithareferencepoint

42. Proximity sensor
Proximity-formofpositionsensors,itdetectstheobjectspresence
orabsenceonsomewhere.
Inductance,capacitance,photoelectricandhalleffectsaremost
widelyusedproximitysensors
e.g.sensorstodetectseatbelton/off,dooropen/close,andsoon.
Inductiveproximitysensors
itutilizetheeddycurrentgeneratedwhenametallicelementis
placedwithintheproximityofanelectromagneticcoil.Itdetectsall
metals,ferrousmetalsonly,ornon-ferrousmetals
Capacitivesensors
Itdetectsallmaterials.Theproximityoftheanobjectchangesthe
gapandeffectsthecapacitance

43. cont.
Photoelectricsensors:-itdirectlyalignedwithaninfrared
lightsource.
Theproximityoftheobjectinterruptsthelightbeamcausing
thevoltageleveltochange.
Halleffect.Isnon-contacttypesensor.Voltageisproduced
whenacurrentcarryingconductorisexposedtoatransverse
magneticfield.Thevoltageisproportionaltotransverse
distancebetweenthehalleffectsensorsandanobjectinits
proximity.
Ultrasonicsensoritdetectsthepresenceofobjectsby
measuringthetraveltimeofahighfrequencysoundwave.

44. Position sensors
Linear displacement sensors :-it used to monitor the thickness or
other dimensions of sheet materials, the position or presence of a
part, the size of a part.
Angular displacement methods
It used to monitor the angular displacement of shafts
e.g. photoelectric sensor .

45. cont.
Basic types of displacement or position sensors
1.Contact devices
➢Limit switches
➢Resistive position transducers
2. Non contact devices
➢Magnetic sensors, including hall effect and magneto-resistive
sensors.
➢Photo electric sensors, proximity sensors
Photo electric sensors

46. Measuring Displacement
1.Potentiometers
Potentiometersareverycommondevicesusedtomeasure
displacement.Itprovidesdisplacementinformationbymeasuring
thevoltagedropacrossaresistor
Itmeasurethedisplacementbasedonpotentialdifference.
❑Alinearpotentiometerisusedforlinearmeasurementsand
❑Angularpotentiometerisusedforangularmeasurements.
e.g.LVDT(Linearvariabledifferentialtransformer).Itgivesan
a.c.voltageoutputproportionaltothedistanceofthetransformant
coretothewindings.

47. 2. Velocity and motion sensors
1.Incremental Encoder
It can be used for measuring angular velocity, it uses number
pulses produced per second being determined.
2. Tachogenerator
Used to measure angular velocity, it is essentially a small electric
generator, consisting of a coil mounted in magnetic field. When the
coil rotates and alternating emf is induced in the coil, the size of the
maximum emf being a measure of the angular velocity.

48. Velocity Sensors
Tachometers
Tachometersisapassiveanalogsensorswhich
providesanoutputvoltageproportionaltothe
velocityofashaft.Thereisnoneedforexternal
referenceorexcitationvoltage.
whentachometershaftrotates,thetachometrygives
aDCoutputvoltage.

49. 3. Force and Torque sensors
Force and torque sensors operate on the same principles. There are
three main types of force and torque sensors:
1.Spring displacement based force/ torque sensors
2.Strain-gauge based force/torque sensors
3.Piezoelectric based force sensors.

50. Force measurement
Force:themeasurementoftheinteractionbetweenbodies.
Themostcommonlyusedsensorsaregenerallybasedon
eitherpiezoelectricquartzcrystalorstraingagesensing
elements.
1.Quartzforcesensors
Itusedforthemeasurementofdynamicoscillationforces,
impact,orhighspeedcompression/tensionforces.
Itutilizesthepiezoelectricprinciples,wheretheapplied
mechanicalstressesareconvertedintoanelectrostaticcharge
thataccumulatesonthesurfaceofthecrystal.

51. cont.
The quartz crystals of a piezoelectric force sensor generates an
electrostatic chargeonly when force is applied to or removed from
them.

52. Cont.
2.Straingaugeloadcell
Adeviceusedtomeasurethesmallchangesin
dimensioncalledstraingagesduetoapplied
force.
Straingaugeloadcell-useofelectricalresistance
tomonitorthestrainproducedinsomemember
whenstretched,compressedorbent.

53. Force-sensing resistor FSR
It uses electrical resistance to measure the force applied to the
sensor. It is made using polymer film technology.
When no pressure is applied to it, the sensor has an infinite
resistance.

54. Torque sensors
Measurementoftorqueisdoneusingtwodifferentconfigurationof
sensorsthesearethereactiontorquesensorsandtherotating
torquesensors.
Reactiontorquesensors–isusedtomeasuretorqueinnon-
rotatingapplications.Thesensorisstationary,andtheshaftofthe
partwhichthetorqueneedtobemeasuredisconnectedthrougha
couplingtothesensorandAutomotivebreaktorquesensing.
Usedtomeasureamotortorqueoutputatzerospeedorthestarting
torque.Andusedtomeasurebearingfriction.
Therotarytorquesensorontheotherhandisusedtomeasure
torquebetweenrotatingdevices.Fanandblowertestingand
clutchtesting

55. 4. Temperature sensors
TypesofTemperaturesensors
1.Sensorswhichchangephysicaldimensionsasafunctionof
temperature
2.Sensorswhichchangesresistanceasafunctionoftemperature
(RTDandthermistors)
3.Sensorswhichworkbasedonthermoelectricphenomena
(thermocouple)

56. cont.
Mostmetalsandfluidchangetheir
dimensionsasafunctionoftemperature.
e.g.mercuryinglassthermometerisused
tomeasuretemperaturebecauseitsvolume
isincreasedproportionallywiththe
temperature.
Itusesthetransductionprinciplethatthe
volumeofthemercuryexpandsasalinear
functionoftemperature.
1.Temperaturesensorsbasedondimensionalchange

57. cont.
2.Temperaturesensorsbasedonresistance
RTD(resistancetemperaturedetectors)temperaturesensors
operatesonthetransductionprinciplesthattheresistanceofthe
RTDmaterialchangeswiththetemperature.
Thentheresistancechangecanbeconvertedtoaproportional
voltageusingWheatstonebridgecircuit.
Thermistorisaresistance-basedtemperaturesensormadeof
semiconductormaterials.

58. cont.
Thermistortemperaturesensors
Thermistorsaresemiconductordevicewhoseresistancechangesas
thetemperaturechanges.
Athermistorhasaveryhighsensitivitytotemperaturechanges,
Theyaregoodforverysensitivitymeasurementsinalimitedrange
ofupto100°C.
❑Theresistanceofthesensingelementreducesexponentially
withthetemperature.
Itisamixtureofmetaloxideschromium,cobalt,iron,manganese
andnickel:semiconductors.
ResistancedecreasesinaverynonlinearmannerwithYincrease
intemperature.

59. Cont. 3.Thermocouples
Itisthemostpopular,easytouseandinexpensivetemperaturesensors.
Ithastwoelectricalconductorsmadeofdifferentmetals.Thetwo
conductorsconnectedasshowninfigure.
Theconnectionbetweenthetwoconductorsatbothendmustforma
goodelectricalconnection.
Ifoneofthejunctionsisataknown
referencetemperature,thenthe
voltagebetweenthenodesisa
functionofthedifferencebetween
thetemperaturesofthetwojunctions.
Thisfactisusedtoindicatethe
temperatureoftheothernode.

60. 5. pressure sensor
➢Absolutepressureismeasuredrelativetoperfectvacuumwhere
thepressureiszero.
➢Thelocalatmosphericpressureisthepressureduetotheweight
oftheairoftheatmosphericattheparticularlocation.
➢Pascal’slawstatesthatpressureinacontainedfluedis
transmittedequallyinalldirections.usingthisphysical
principles,abarometerisusedtomeasureabsolutepressure.
➢Thepressuresensorsmeasuretherelativepressurewithrespect
tothelocalatmosphericpressure.
➢However,somesensorsmeasureapressurerelativetothe
vacuumpressure.Itisreferredtoastheabsolutepressure.

61. cont.
Displacement basedpressuresensors
Itconvertthepressureintoaproportionaldisplacement,andthen
convertthisdisplacementtoproportionalelectricalvoltage.
Strain-gauged basedpressuresensor
Pressureisproportionaltothestraininducedonthediaphragm.
Thisstrainisconvertedintovoltageoutput
Piezoelectricbasedpressuresensor
Thisoneisthemostversatilepressuresensors.Itconvertaforce
actingonthepiezoelectricelementintoproportionalvoltage.

62. 6. Flow sensors
Theventurimeterandorificeplaterestricttheflowandusethepressure
differencetodeterminetheflowrateeithertheflowislaminaror
turbulent.
Thepilottubepressuretubeisanotherpopularmethodofmeasuring
flowrate.
Therotameterandtheturbinemeterswhenplacedintheflowpath,
rotatesataspeedproportionaltotheflowrate.
Electromagneticflowmetersusenoncontactmethod.Magneticfieldis
appliedinthetransversedirectionoftheflowandthefluidactsasthe
conductorstoinducevoltageproportionaltotheflowrate.
Ultrasonicflowmetersmeasurefluidvelocitybypassinghighfrequency
soundswavesthroughfluid.

63. 7. Light sensors
Lightintensitysensorssuchasphototransistors,photoresistorsand
photodiodesarethecommontype.
Acommonphotosensorsismadeofcadmiumsulphide,its
resistanceismaximumwhenthesensorsisindark.
Whenitexposedtolight,itsresistancedropsinproportiontothe
intensityoflight.

64. vibration sensor
vibration is measured by either accelerometers or vibrometers . It
is important in safety devices, machinery and flexible structures.
These two devices have a similar operating principles but differ in
their natural frequency and damping.
Themotionofthestructureis
transferredtotheseismicmass
throughthesupportspringand
damper.

65. Vision systems
Visonsystemsisalsocalledcomputervisionormachinevision,.
Alsocalledsmartsensors.
Avisionsystemcanbeusedtomeasureshape,orientation,area,
defects,differencesbetweenparts,etc.
Therearethreemaincomponentsofavisionsystem
1.Visioncamera
2.Imageprocessingcomputersandsoftware
3.Lightningsystem

66. cont.
Components and function of a vison system
It forms an image by measuring the reflected light from objects in
its field of view .

67. selection of sensors
Factorswhichmustbeconsideredinselectingasuitablesensorsto
measurethedesiredphysicalparameters.
❑Range–Differencebetweenthemaximumandminimumvalue
ofthesensedparameter.
❑Resolution-thesmallestchangethesensorscandifferentiate
❑Accuracy-differencebetweenthemeasuredvalueandthetrue
value
❑Precision-abilitytoreproducerepeatedlywithagiven
accuracy.
❑Sensitivity-ratioofchangeinoutputtoaunitychangeoftheinput.
❑Linearity-percentageofdeviationfromthebestfitlinearcalibration
curve

68. cont.
Zerodrift-thedepartureofoutputfromzerovalueoveraperiodof
timefornoinput.
Responsetime-thetimelagbetweentheinputandoutput
Bandwidth-frequencyatwhichtheoutputmagnitudedropsby3db
Resonance-thefrequencyatwhichtheoutputmagnitudepeak
occurs.
Operatingtemperature-therangeinwhichthesensorsperformsas
specified
Deadband-therangeofinputforwhichthereisnooutput
Signaltonoiseratio-ratiobetweenthemagnitudeofthesignals
andthenoiseattheoutput.

69. signal conditioning
Signalconditioning
itisaprocessofsignalamplification,filtering,electricalisolation
andmultiplexingofsignals.
Sincemanytransducersrequireexcitationcurrentsorvoltages,
bridgecompletion,linearization,orhighamplificationforproper
andaccurateoperation.
Devicesforsignalconditioning:-amplifiers,filters,highpass
filters,notchfilters,switchingamplifierandsoon

70. signal conditioning
Signal
conditioning
Too small
Analog
Resistance change
Voltage change
non linear
Interference
Amplified
Digital
Current change
Current chage
Rectified
Linearized

71. filtering
Filteringistheprocessofattenuatingunwantedcomponentsor
noisefromthesensoroutputandallowingothercomponentsto
pass.
Typesoffilters
➢Lowpass
➢Highpass
➢Notchand
➢Bandpass

72. bridge circuit
Abridgecircuitisusedtoimprovethe
accuracyandsensitivityoftheoutputofcertain
sensors.
Itiscommonlyusedtoprocesssignalsfrom
resistive,capacitive,andinductivetype
sensors.
Itismadeupofresistiveelementwitha
constantDCvoltageinput.Thisfour-arm
bridgecircuitisknownastheWheatstone
bridge.
❑Andusedtoprocessthesignaloutputfromstraingagesand
resistance-basedthermalsensors.

73. G. Assignment
Research the working principle and identify the type of sensors
used in the following application
a.Kitchen oven
b.car door locking
c.kitchen stove and boiler
d.Refrigerator door closure
e.Laptop cooling system
f.Vehicle engine cooling system
g.Servo robot
h.car airbag system
i.Infrared thermometer

74. cont.
ConsideraPV(photovoltaic)plateautomaticpositioncontrol
system.Whichusedtoimprovethesunlightabsorbingefficiency
ofthesolarsystembytiltingthePVpaneltowardsthesunlight’s
intensitythroughouttheday.Whattypeofsensoryouwill
recommend.Andjustifyyourselection,andexplainhow?

75. Actuators
Actuators are basically the muscle behind a mechatronics system
that accepts a control command (mostly in the form of an electrical
signal) and produces a change in the physical system by generating
force, motion, heat, flow , etc.
It is responsible for transforming the output of a microprocessor or
control system into a controlling action.

76. cont.
➢Actuators produce physical change such as linear and angular
displacement.
It also modulate the rate and power associated with these changes.
➢Selecting the appropriate type of actuator is one of the
important aspect of mechatronics.
➢Actuators can be classified based on the type of energy such as
electrical, electromechanical, electromagnetic, hydraulic or
pneumatic type.

77. Electrical actuators
Electrical switches are the listed actuators for most of the on-off
type control action.
Switching devices such as diodes, transistors, triacs, MOSFET, and
relaysaccept a low energy level command signal from the
controller and switch on or off electrical devices such has motors,
valvesand heating elements.

78. Electro magnetic principles
Many actuators rely on electromagnetic forces to create their action.
When a current carrying conductor is moved in a magnetic field, a
force is produced in a direction perpendicular to the current and
magnetic field directions.
➢The electromagnets are used extensively applications that require
large forces.
➢The most common electromagnetic actuators are solenoid.

79. solenoids and relays
Asolenoidsconsistsofacoilandamovable
ironcorecalledthearmature.Whenthecoilis
energizedwithcurrent,thecoremovesto
increasethefluxlinkagebyclosingtheairgap
betweenthecores.
Theforcegeneratedisproportionaltohe
squareofthecurrentandinversely
proportionaltothesquareofthewidthofhe
airgap
Itusedinhomeappliancelikewashing
machinevalves,automobiledoorlatchesand
pinballmachine

80. Electro mechanical actuators
Electric motors
➢The electric motor that converts electrical
energy to mechanical motion.
➢It consists of either permanent magnets or
wire coils.
➢The rotor is the part of the motor that
rotates.
There is a small air gap between the rotor and the stator where the
magnetic fields interact .

81. cont.
When selecting a motor for a specific mechatronics application, the
designer must consider the following factors such as speed range,
torque-speed variation, reversibility, operating duty cycle, starting
torque and power required.
Types of motors
➢DC motors
➢Brush type DC motors
➢AC motors
➢Steeper motor
➢Servomotor and so on

82. Hydraulic and pneumatic actuators
Hydraulic system; designed to move large loads by controlling a
high pressure fluid in distribution lines and pistons with mechanical
or electromechanical valves.
➢It uses pressurized oil
that is incompressible.
➢It is suited for generating
very large force coupled
with large motion.

83. Pneumatics
It is similar to hydraulic systems, but it uses compressed air as
working fluid.
Use air under pressure that is most
suitable for low to medium force ,
short stroke ,and high speed
applications.

84. pumps
s

85. Assignment
1) For each of the following applications, what is a good choice of the
type of electric motor used? justify your choice
1.Robot arm joint
2.Ceiling fan
3.Electric trolley
4.NC milling machine
5.electric crane
2) List and explain Smart material actuators with working principle and
its area of applications?
1.Disk drive motor
2.Industrial conveyor motor
3.Washing machine
4.Clothes dryer
5.Disk drive head actuator

86. Thankyou!!
?