ADVANCEDEV3PROGRAMMINGLESSON

GyroSensorRevisitedBySanjayandArvindSeshan

1. Learnabouthowolderandnewergenerationsofgyrosensorseffectthecalibrationprocess

2. Learnhowtohowtodealwithgyrodriftwiththisupdatedinformationaboutthegyrosensor.

Prerequisites:Datawires,Loops,Logic&ComparisonBlocks,IntroductiontoGyro

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LessonObjectives

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ì Reset:Currentvalueofthegyrosensorangleissetto“0”.Thisiswhatthegyroblockwithmodesetto“reset”does.

ì Calibration:Thegyrocalibrateswhatitconsiderstobe“still”.Thissetsboththecurrentgyrosensorrateandangleto“0”.Thistypicallyoccurswhenthegyroisconnected.

ì Somepeoplerefertocalibrationasa“hardreset”.Wewillcallthiscalibratethroughthislessontoreducetheamountofconfusion.

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TermstoKnow

ì IthasbeenbroughttoourattentionbyMr.SamLastfromNorthCarolinathatcertaingyrosareactingdifferently.

ì Oncertaingyrosensors,thecommonlyusedcalibrationcodeforthegyro(switchingbetweenangleandrate),doesnotwork(i.e.doesnotcausethegyrotoperformarecalibration).

ì Thisisabigissueforanyoneusingoneofthegyrosensorsthatdoesnotrecalibratewiththiscode.

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WhyRevisittheGyro?

Strategy1:

Strategy2:

Strategy3:

Strategy4:

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RecalibrationMethodsfrom“IntrotoGyro”

ì Weobtaineddatafrom30+gyrosensorspurchasedinvariousyearsaroundtheworld

ì Strategy4code(fromIntroductiontoGyroLesson)providesasimplewaytotestifyouhaveasensorthatsupportsrecalibrationornot.ì Onsensorsthatperformtherecalibration,it

takes3secondstorunthiscode.ì Onsensorsthatdonotperformthe

recalibration,thecoderunsin<.1seconds.ì Weaddedsometimercodetotestagyro

sensorsbyrunningthreerecalibrationsandaveragingtoseehowlongtheytake.

ì Wethoughttheproblemmayberelatedtothecodeonthebottomofthegyro(showninredcircle)– so,werecordedthisaswell.

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TestingtheGyroSensors

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ì Thereisacorrelationwiththecodesprintedonthegyrosthemselves andwhetherornottheyrecalibratecorrectly.

ì AllgyrosensorsendinginN2andN3worked.AllgyrosensorsendinginN4,N5andN6didnotwork.

ì WeonlyownN3andN4.Testsontheotherswereconductedbyfriends.

ì Note:Ifyoucompletethislessonanddiscovernewnumberstoaddtothelist,pleaseemailthemtousatteam@ev3lessons.com.

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Results

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18N220N248N2

01N302N303N304N305N306N316N317N319N342N343N344N345N347N349N350N351N3

SampleGyroSensorCodes

09N415N420N421N438N439N450N4

13N517N521N522N527N528N536N545N5

OldType NewType03N605N606N615N617N620N621N623N6

ì Method1:YoucanlookforthetinycodeprintedonthegyrosensorsandlookatthelasttwoLetter-Digitcombination

ì Method2:YoucanrunthetestcodewehaveprovidedforyouonEV3Lessonsanditwilltellyouwhichsensoryouhaveandifthetraditionalrecalibrationoranalternativerecalibrationmethodisneeded.

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WhatSensorVersionDoYouOwn?

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PhotoCredit:ThomasMadeya

“N5”“N3”

Seenextslideforzoomedinversions

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CloseupViewoftheSampleCodes

PhotoCredit:“N5”and“N6”ImagesbyThomasMadeya

“N5”“N3” “N4” “N6”

• WhereverthispresentationmentionsN4,theresulthasbeenconfirmedforN5 andN6aswell.

• WhereverthispresentationmentionsN3,theresulthasbeenconfirmedforN2aswell.

WhatifDon’tOwnanN2/N3Sensor?*

HardwareSolutionì Unplugandre-plugyourgyro

sensorwhilemakingsureyourrobotisstill

ì ThistechniquerequiresaccesstotheEV3portsandispronetofailuresinceyoumayshaketherobotasyoure-plugthewire.

SoftwareSolutionì Ifyoureadtheportthegyrois

connectedtoasaninfraredsensorandthenreaditagainasagyrosensor,itseemstoforcearecalibrationofthegyro.

ì Seethenext4slidesforupdatedrecalibrationcodeforthe“N4”andupsensors.(Canbeusedwith“N3”andbelowaswell.)

ì Note:Didnotworkreadingthesensorascolor,ultrasonic,touchortemperature.

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*Aswediscovermoresolutions,thisslidewillbeupdated.9

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RecalibrationStrategy5

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First,readingthegyroasanIRsensorandthenasagyrocausesthegyrotorecalibrate.

Second,addawaitblocktogivethesensorabitoftimetofullyrecalibrate.Ourmeasurementsshowthat4 secondsissafe.NotethattheStrategy1codeinIntrotoGyro,recalibrationonlytook0.1seconds.

Notefor“N3”sensorusers:intherestofyourprogram,youshouldonlyusethe“angle”modesofthegyro.Usingthe“rate”or“rateandangle”modewillcausethegyrotorecalibrate.“N4”sensoruserscanchangemodeswithoutcausingarecalibration.Modechangesdo“reset”theangleto0.

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RecalibrationStrategy6

Thisversionofthecalibrationleavesthegyroinrate+angle mode.Thisisusefulfor“N3”usersifyouusetherateoutput.

Thisversiontakesalittlebitlonger(4vs.3seconds)thantheStrategy2codeinIntrotoGyro.

Notefor“N3”sensorusers:intherestofyourprogram,youshouldonlyusethe“rate+angle”modesofthegyro.Usingthe"angle"or“rate”modewillcausethegyrotorecalibrate.Also,***DONOT***usethegyroresetmode- thisforcesthegyrointoanglemodewhichwillcausealong3secondrecalibration.“N4”sensoruserscanchangemodeswithoutcausingarecalibration.Modechangesdo“reset”theangleto0.

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RecalibrationStrategy7

Notefor“N3”sensorusers:intherestofyourprogram,youshouldonlyusethe“angle”modesofthegyro.Usingthe“rate”or“rateandangle”modewillcausethegyrotorecalibrate.“N4”sensoruserscanchangemodeswithoutcausingarecalibration.Modechangesdo“reset”theangleto0.

Thisversionofthecalibrationleavesthegyroinanglemode.Thisisprobablythemostcommonwaytousethegyro.Thiscodetakesabout4sectorun(vs.0.1secfortheStrategy3codeinIntrotoGyro)

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RecalibrationStrategy8

Notefor“N3”sensorusers:intherestofyourprogram,youshouldonlyusethe“rate+angle”modesofthegyro.Usingthe"angle"or“rate”modewillcausethegyrotorecalibrate.Also,***DONOT***usethegyroreset- thisforcesthegyrointoanglemodewhichwillcausealong3secondrecalibration.“N4”sensoruserscanchangemodeswithoutcausingarecalibration.Modechangesdo“reset”theangleto0.

Thisversionofthecalibrationleavesthegyroinrate+anglemode.Thisisusefulfor“N3”usersifyouusetherateoutput.

ì ThenewgyrocalibrationstrategiesinthislessonworkforeithertheN2-N3orN4-N6sensors

ì Notethatallthenewrecalibrationstakeabout3-4seconds.Thisissignificantlymorethanthepreviousstrategy1and3(intheIntrotoGyrolesson)whichleftthegyroinanglereadingmode(0.1secvs.3-4secs)ì Therefore,ifyouhaveolderN2andN3gyros,youmightwanttouse

theoldcodethattooklesstimetorecalibrate.

ì ThenewerN4-N6sensorsallowyoutousedifferentgyromodesinsideaprogramwithoutcausingarecalibration.

ì Conclusion:TherewasahardwarechangebetweentheN3andN4gyros.TheoldergyroslikelyuseISZ-655(asingle axis gyro chip).

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Discussion

ì Thankstothecommunitysendinginallthecodesonthegyrosensors,itdoesappearthatthereisadatecodeoneverygyrosensor.45N5 =[Week][Factory/Electronics][Year]=Week45,N,2015

ì ByrunningEV3Dev,DavidLechner,wasabletoidentifythatnewersensorshavesomeadditionalsecretmodesenabledbythenewhardwareinsidethesensor.Thenewersensorshaveadual-axisgyrochipsoitcanmeasureangleandrateaboutasecondaxis(paralleltothecable)

ì Note:Thesemodesarenotaccessible throughthestandardEV3-GGyroblockevenifyouownthenewergyrosensors.Themodesarereferredtoas"TILT-ANG"and"TILT-RATE”inthesensoritself.ì Watchhttps://youtu.be/KjlT0BUJr-w forhowDavidLechner discovered

thedifferentmodes.

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WhatisGoingOn?

Credit:ThisinformationonthisslidewasprovidedbyDavidLechner andJorgePereira

ì Lechner believesthatwithN4,N5andN6sensors,sincetherearenew(hidden)modesthatmeasurerotationaroundadifferentaxis,thesensornolongerresetswhenswitchingmodesfromangletorate.

ì TheIRSensorBlockworksinoursolutioncodebecauseitforcesthesensorcommunicationtotimeoutandcausesthesensortoreset.ThisisbecausetheLEGOfirmwarehandlestheIRsensordifferently(longertimeout).

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WhatDoesThisMeanforCalibration?

Credit:ThisinformationonthisslidewasprovidedbyDavidLechner andJorgePereira

ì ThistutorialwaswrittenbySanjaySeshanandArvindSeshan

ì Morelessonsatwww.ev3lessons.com

ì ThankyoutoMr.SamLastforfirstreportingthisissuetous.

ì ThankyoutoDavidLechner forinvestigatinganddiscoveringthehiddenmodesofthenewersensor.

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Credits

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

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