ADVANCEDEV3PROGRAMMINGLESSON

ByDroidsRobotics

SquaringorAligningonaLine

ì Learnhowtogetyourrobottosquareup(straightenout)whenitcomestoaline

ì Learnhowsquaring(alsoknownasaligningonaline)canhelptherobotnavigate

ì Learnhowtoimproveinitialcodeforaligningbyrepeatingatechnique

ì PracticecreatingausefulMyBlock

ì Prerequisites:MyBlockswithInputs&Outputs,DataWires,ParallelBeams,ParallelBeamsSynchronization

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LessonObjectives

ì MoveSteeringletsyoucontrolbothmotorsatthesametime

ì Whatifyouwanttomoveorstoponemotoratatime?ì UsetheLargeMotorBlock

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Review:MotorMovements

LargeMotorBlock LargemotorblockinONmode/OFFmode

ì Aligningonalinehelpstherobotnavigateì Robotsgetangledastheytravelfartheror

turn(theerroraccumulates)ì Aligningonalinecanstraightenoutarobot.ì Aligningcantellarobotwhereitiswhenit

hastotravelfar

ì ExampleGoal:YourrobotmustdeliveranobjectonlyinsideasmallENDarea.Thedistancebetweenstartandendis8feetì Doyouthinkyourrobotcantravel8feetand

continuetobestraight?

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WhyAlignonaLine?

Start

8ft

Challenge:Maketherobotstraightenout(align/squareup)

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ThreeEasyStepstoAlign

STEP1:Startbothmotors

STEP2:Stoponemotorwhenthesensoronthecorrespondingsideseestheline

STEP3:Stopmovingthesecondmotorwhenthesensoronthatsideseestheline

Hints:UseaLargeMotorBlock,UseParallelBeams,UsetheLargeMotorBlock (Thisslideisanimated)

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WhatAligningShouldLookLike

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NotesAboutOurSolution:

ì Oursolutionuses2ColorSensors(connectedinPorts1and4).

ì Oursolutionassumesthatthecolorsensoronport1isnexttothewheelonmotorportBandcolorsensoronport4isnexttothewheelonmotorportC.

ì Youshouldadjusttheportsasneeded

ì YourcolorsensorsshouldNOTbeplacedrightnexttoeachother(Seeredboxesbelowinrobotimage.Thesearethecolorsensors.)

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BasicSolution:MovingUntilLine

ì Whenyouhavetwoormorebeamsyoudonotknowwheneachbeamwillfinish.

ì Ifyouwantedtomoveafterthealignfinishesyoumighttrytoaddamoveblockattheendofoneofthebeams.ì Note:ThiswillnotworkbecauseEV3codewillplayyourmoveblock

withoutwaitingfortheotherbeamtofinish.ì Solution:Youneedtosynchronizeyourbeams.Tolearnmoreabout

synchronizationandsolutionsgototheAdvancedEV3Lessons.comLessononSyncBeams:PPTX, PDF ,EV3Code

ì TheproblemofsynchronizationcanalsobesolvedbymakingaMyBlockoutofthealigncode.ì MyBlocksalwayswaitforbothbeamstofinishbeforeexiting

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Note:Synchronization&ParallelBeams

ì Whatdoyounoticeaboutthesolutionwejustpresented?ì Therobotisn’tquitestraight(aligned)attheendofit.ì Bothcolorsensorsareontheline,buttherobotstopsatan

angle.

ì ChallengeContinued:Thinkabouthowyoucanimprovethiscodesothattherobotendsstraighterì Hint:Canyourepeatthelastprocessbylookingforwhite?ì Thisassumesthattheblacklinewewerestraighteningoutonhas

whiteonbothsides.

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ImprovingYourAlignCode

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ImprovedSolution:CreateaMyBlock

A

A. HighlightalltheblocksthengotoMyBlockBuilder

B. Add2inputs:oneforpowerandoneforcolor

RefertotheMyBlockswithInputs&OutputslessonifyouneedhelpsettinguptheMyBlock

B

C.Wiretheinputsinthegreyblock.ThecolorinputconnectstoboththecolorinputinbothWaitBlocks.ThepowervaluegoesintothepowerinputinbothMoveSteeringBlocks.

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ImprovedSolution:WireMyBlock

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ImprovedSolution:MyBlockWithDualStageFix

ì Youwillgetbetterresultsì ….ifyourcolorsensorsareabout1cmfromthegroundì ….ifyoushieldyourcolorsensorsì ….ifyoudon’tcomeatthelineatsteepanglesì ….ifyoukeepyourcolorsensorsspreadapart

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TipsforSuccess

1. WhatdoesAligningonaLine/Squaringmean?Ans.Itmeanswhenyourrobotcomesatanangle,itcanusealinetostraightenout

2. WhydoesSquaringhelpwhenyoutravellongdistances?Ans.Robotsdonotmoveaccurately/straight.Squaringcanhelpyouknowwhereyouareandstraightenout.

3. Whymightitbeusefultorepeatthealignmentprocessmultipletimes?Ans.Yourrobotwillgetstraightereachtimeyourepeat

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DiscussionGuide

ì ThistutorialwascreatedbySanjaySeshanandArvindSeshanfromDroidsRobotics.ì Author’sEmail:team@droidsrobotics.org

ì Morelessonsatwww.ev3lessons.com

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Credits

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