avr跳舞雙足機器人課程設計

CourseProjectDocumentation

BEFinalYearProject

BipedalRobot

TEAM:17

TanmayKavathekar

TableofContents

1.Introduction..................................................................................1

2.ProblemStatement......................................................................2

3.Requirements………...3

4.Implementation............................................................................4

5.TestingStrategyandData...........................................................6

6.DiscussionofSystem..................................................................8

7.FutureWork.................................................................................9

8.Conclusion...................................................................................10

9.References..................................................................................11

1.Introduction:

Researchintheareaofroboticsstartedinthe20thcenturyandhasresultedinrobotsofvarioustypes,manybeingapermanentpartoftoday'sindustry.Theserobotsperformthejobsthatarephysicallydemanding,monotonousorevenhazardoustohumanbeings.Also,theyincreasetheworkrateandthequalityofproductsinplaceswherefactorssuchasspeedandaccuracyareessential.Today,robotsarefoundinalmostallmodernassemblyproductionlines.

Usually,theserobotsuseasmallsetoffixedmovementpatternswhichlimitstheirpossibleinteractionswiththesurroundings.Also,theyareseldomincontactwithhumans.Researchconcerningrobotscapableoffunctioninginnormalhumansurroundingsandinteractingwiththehumanenvironmentisstillatanearlystage.Apartofthisresearchareaincludesthedevelopmentofrobotsusingbipedallocomotion,i.e.walkingontwolegs,astheserobotscouldfunctionandperformtasksinahumanenvironmentwithoutadjustingthesurroundingstothem.Robotsusingbipedallocomotionarecalledbipedrobots,andareoftenfoundwithintheclassofrobotsknownashumanoidrobots.

2.ProblemStatement:

Theaimoftheprojectistodesignanautonomousrobotwhichhasastructuresimilartohumanlegs.Therobotwillhave6DOF(DegreeOfFreedom),3foreachleg.

Wealsolearntheconceptofcentreofgravity(CG)andhowittheconceptisappliedbythehumanbodytomaintainstabilitywhilewalking.

Atthesametimewelearnthedifferentphasesthroughwhichthelimbsundergotocreateasmoothwalkingmotion.

Weuseservomotorstobuildtherobotasitwillgivemoreaccuracyandcontroltocreateasmoothmotion.Alsocontrollingservomotoriseasierthandcorsteppermotors.

ThecontrollertobeusedintheprojectshouldhavemoretimerstogeneratePWMsignalswhichareusetocontolthemotors.

3.Requirements:

A)HardwareRequirements:

Microcontroller:Atmega640(Developmentboard).

Motors:6Servomotors(NRS-785).

Servojacketskits:6kitstoholdthemotors.

Servoarmkits:8kitstolinkthemotorstogether.

Acrylicsheet:Itisrequiredtoconnectthetwolegsandasfeet.

B)SoftwareRequirements:

AVRstudio:Itisusedtowrite,compileanddebugtheprogram.

AVRbootloader:Itisusedtoloadthehexfileintothecontroller.

4.Implementation:

A)Working:

WefirstwriteaprogramtogeneratePWMsignals.Thepulsewidthvariesfrom0.6ms-2.2msforarangeof0-180degrees.Sincethetimerisanuptimethemaximumvaluestoredisfor180degrees.Thususingthecrystalfrequencytocalculatetimeperiodof1clockcyclethevaluefortimerisreloadediscalculated.

Theservosarethentestedandalignedat90degrees.Afterwhichrobotisassembledusingtheservoarmandjacketkitsandtheservosaretheninterfacedtothemicrocontroller.

Whilechoosingmaterialsfortherobotweightisaveryimportantfactorasitwilldeterminethetorquethemotorhastosupplytocarrytheweight.Hencewehaveusedaluminiumjacketsandacrylicsheetasbase.

Whileusingservosthesupplyfromtheboardisinsufficientaseachservoneedsaround2amperesforrunning,thuswehaveusedaspecialsupplyof15amperes.

Afterwhichweprogramtherobottherobotforvariousmotions.

Astheresponseoftheservoisveryquickweuseadelaylooptoslowdowntheservo.

ThemaintaskwhileprogrammingistomaintaintheCG(centreofgravity)oneitherofthelegsatalltimessothattherobotisabletobalanceitself.

B)Algorithm:

GenerallywalkingcycleconsistsoftwostepsnamelyInitializationandWalking.

Initialization:

IntheInitializationsteptherobotwillbeinbalancedconditionandinthissteptheservomotorsaremadetoreturntohomeposition.

Walking:

Walkingstepisfurtherclassifiedintosixphases.

Phase1–DoubleSupport:

Inthisphaseboththelegsareinsamelineandthecentreofmassismaintainedbetweenthetwolegs.

Phase2–SingleSupport(Pre-Swing):

Inthisphaseboththeanklejointsareinactuatedinrollorientationwhichshiftsthecentreofmasstowardstheleftlegandtherightlegwillbeliftedupfromtheground.

Phase3–SingleSupport(Swing):

Inthisphase,therightlegisliftedfurtherandmadetoswingintheair.Hipandkneejointsareactuatedinpitchorientationsothatrightlegismovedforward.

Phase4–PostSwing:

Inthisphasetheliftedlegisplaceddownwiththeactuationofanklejoints.

Phase5and6

TheyarethemirrorimageofPhase2andPhase3.AfterPhase6,motioncontinues

5.TestingStrategyandData:

Motortesting:

First,eachmotoroftherobotistestedforproperfunctioning.Thenthemotorarealignedat90degrees.Whentherobotisassembledeachservoisalignedat45and135degreestocheckthedirectionofmotion.

Robottesting:

Wetriedtotilttherobotononeleg,butitdidnotbalanceitselfandtoppledimmediately.AsaremedywetiltedtheankleservosothattheCGoftherobotshiftedslightlyovertheotherleg,beforetiltingtherobotovertheotherleg.

Whiletiltingtherobotoveronelegweobservedthatthemotionwastoosudden,henceweintroduceda“for”loopsothattherewasadelayafterevery2degreethemotormoved.

Thenwewentforwardcreateasidewaysmotionbytiltingtheanklejointandpushingitsuddenlytotheground.Wegetbettermotionifthesurfaceisplain.

Thenwemoveforwardtoperformakickingmotion.Atthisjuncturewefoundthatthesupplyusedfromtheboardwasinsufficienttodrivemorethan2motors.Henceweusedasupplyof5V,15A.

Afterkickingthenextstepwastocompletetheentirewalkingmotion.

Thefollowingimagesshowtheworkingoftherobotinthedifferentphasesofitswalkingalgorithm.

6.DiscussionofSystem:

A)Whatareworkedasperplan?

Constructionoftherobot:

Therobotwasconstructedwiththemotorsperfectlyalignedat90degrees.Alsotherobotisverylightinweightduetotheservoarmandjacketsaremadeofaluminium.

Efficiencyofwalkingalgorithm:

Thealgorithmwasefficientlyabletodividethewalkingmotionintovariousphasesmakingiteasiertoprogramtherobot

MotionControl:

Thevariousmotionoftherobotlikesidewaysmotion,kickingmotionandwalkingmotionwereprogrammedandexecutedaccurately.

C)Changesmadeinplan:

Therehardlychangesmadeintheplanasthethingswentaspertheplansandwhatwehadenvisioned.

7.FutureWork:

Inourcurrentimplementation,wehaveusedadevelopmentboardtocontroltherobotlateraseparatecircuitcanbemadeandmountedontherobot.

Theupperbodycanbeaddedtothebipedtomakeahumanoidrobot.

WecanhaveforcesensorsandgyrosensorusedtohelprobottakeindependentdecisionsandI/Rsensorstodetectobstacles.

8.Conclusions:

TheBipedalRobothasmanyusesandfutureapplications.Itintroducesusestothechallengesfacedtobuildhumanoidrobots.Italsohighlightsthatfactthatthehumanbodyisreallycomplexmachinewhoseintricateworkingshavealwaysbaffledusandmimickingthemisverydifficult.Theserobotswillbeaboontothequadriplegicpeopleandreplacementtohumansindangerousenvironment.

9.References:

BipedalRobotsbyChristineC.,GuyB.,Gabriel