斯坦福大学网络视频课程跟机器人学Word文档下载推荐.docx

斯坦福大学网络视频课程跟机器人学Word文档下载推荐.docx

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reducedeformationintheradialdirection.

Theactuatorcanbeflexedineverydirectionbycontrollingthepressureineachchamber.

[Inaudible]developedactuatorsranginginsizefrom1millimeterto20millimetersin

diameter.Thisistheformulameteractuator.Thedesigniseasilyminiaturizedbecauseof

itssimplestructure.

Thisisamodifiedversion.Therubberisreinforcedspirallywithfibersothatrotational

movementispossible.Wecanapplytheseflexiblemicro-actuatorstominiaturerobot

manipulators.Byconnectingthemserially,wegetanarmwithmanydegreesoffreedom

andsnakelikemovements.

Thisisaprototypeconsistingoftwoactuatorsandaminigripper.Ithas7degreesof

freedomincludingthegripper.Itcanaccomplishdelicatetasks,whichcouldbehandled

onlywithgreatdifficultybyconventionalrobots.

Constructingminiaturerobotmanipulatorsiseasybecausetheactuatorsalsoactasthe

robotstructure.Ontheotherhad,combiningtheactuatorsinparallelresultsinamultifingered

robothand.Theyformadexteroushandwithadelicatetouch.Thisprototype

consistsoffouractuators,each12millimetersindiameter,andithas12degreesof

freedom.

It’sabletohandlefragileandcomplicatedworkwithease,becausetheactuator’s

deformedtosuittheshapeoftheworkpieceitself.Theboltiseasilytightenedwithonly

roughsettingsofthepositionandorientationofthehandbecausetheactuatorshavesuch

goodcompliance.

Miniaturerobotswithasofttouchandnoconventionallinkscanbecreatedusingthese

actuators.Peopleseetheuseofflexiblemicro-actuators–

So,whatdoyouthink?

Whatwouldbetheadvantagesof

usingpneumaticinthisway?

Yes?

Student:

Probablysaferforalotmoreobjects.

Safer,yousaid?

Sosafetyisavery,veryimportantaspect

ofthedesignofarobot,especiallyiftherobotisgoingtointeractwithhumans,andyou

reallydon’twantthisrobottojustgocrazyandhitandmakealargeimpact.Sosoft

actuationusingpneumaticisverygoodbecauseitbasically–it’scompliant,right.

Nowanotherimplicationofthefactthatyouareusingpneumaticisthestructureofthe

robotisgoingtobelighter,becauseifyouthinkaboutoperatingthesefingerswiththe

motorsor[inaudible]Ithinkaboutanarmwithmotors.Youneedtocarrythemotors,

youneedtoputgears,youneedalotofstructuretohandleit,sodefinitelythisislighter,

safer,moreflexible,compliant,allofthat.

Anydisadvantageyoucansee?

Hardertocontrol?

Yeah.Basically–well,Imean,itdependswhatyouwant

toachieve,butyoucannotexpecttoachievethetasks.Whatkindoftasksyoucannot

controlwiththistypeofactuation?

[Inaudible]motion?

[Inaudible]motionorfastdynamicsifyouwantto

changedirectionsbecause?

Whatistheproblemwiththat[inaudible]?

[Inaudible]

Soyeah,Imeanbasicallytheresponseofthisisgoingto

beslowbecauseyouareusingairpressureandyoucannotpushtheairpressuretoapoint

whereyoucanreallygetfastdynamics.Welllateroninthequarterwewillseeaconcept

thatcombinesthisideaofusingpneumatic,whichislighttocarry,andwouldresultinto

anicelightstructure,combineitwithothertypeofactuationtobringhybridactuationin

awaythatcombinesboththeadvantagesofthelightstructureandthefastdynamicsthat

weneedtoachieveallthedifferenttasksthatwouldrequiretherobottorespondquickly.

Yes?

Isthereanygoodwayto[inaudible]that,like,youdon’tactuallyknowwhere

you’re[inaudible]?

Wellthat[inaudible],youwouldseetherobotwaslike

turning.Okay,anyonewouldliketoanswerthisquestion?

I’msureyouhaveanidea,but,

thisisreallynotfundamentaltotherobotdesign.Itismoreonthefactthatwehaveno

externalfeedbackornotouch,orwearenotusingtheinformationaboutthetouchto

realizethatwealreadyleftthatcontact.

Butthisisactuallysomethingthatyoucanaddontopofthedesignto–likewould–

Whatkindofsensoryyouwoulduse?

Pressuresensor?

Touchsensor,youmeanlikeyouwanttoknowifyouare

touchingornot?

Pressurewouldbe[inaudible]toknowexactlylikehowfaryouare,butwith

somethinglikethat,[inaudible].Like[inaudible]putsomethingthatexactlytellsyouthe

positionoftheend.

Sowecanputasensorattheendthatislocalizedatthe

tipofthefingerandthenwecanfeelwhetherthesensorisonoroff.Thatisjusttouch,

butifyouwantmoreinformationaboutthepressure,youneedasensor,[inaudible]

sensorthatwouldmeasure.

Butthentheproblem–Imean,nowwecomeintoamuchharderproblem,whichisthe

factifyou’reholdingsomething–let’simaginewithyourtwofingersyou’reholding

something.Andthereisalwaysslip,soyouneedtomeasuretheslipsothatyoucan

applylargerpressure.

Andtodothatyouneedthesortofdynamic[inaudible].Sotherehasbeenalotofwork

actuallyinthegroupofMarkCokoskey.Alotofresearchon[inaudible],dynamic

[inaudible]andalsotheideaofusingpressureisaverygoodideabecauseinfact,by

measuringthepressureandthecontrolpressurethereisadifferencebetweenwhatyou

areexpectingandwhatyousee.

Youwillbeabletodeducesomeinformationaboutcontact.Therewasacommentthere?

[Inaudible]sensorsonthesurfaceandusethosetofindtheposition?

Umhm.Nowifyouinstrumenttheenvironment,

obviouslyyouwillbeabletogetalotofinformationabouttheenvironment,butthatis

costly.Soyouwantmoretoputthesensorsontherobot.Butthereisanothertypeof

sensorthatwillgiveyoumoreinformationabouttheenvironmentthat–especiallyabout

whetheryouareincom–Imean,closeornot,liketolocalizeandseewherethingsare.

Toseewherethingsare,whatdowecall?

[Inaudible]Instruction:

Vision.Putcoupleofcamerasandyouwouldseewhereyouarewithrespecttothe

world.Andsoyouhaveamechanism,youhavethecontrollers,butreallyyouneedto

closetheloop.Buttoclosetheloopyouneedperception,andperceptioncoulduse

sensorsintheenvironment,sensorexternalthataremonitoringtheenvironmentor

instrumentationontherobotitself.

Anyway,thiscutedesignactuallywaspursuedforacoupleofyears.Theybuiltevena

bigrobotthatiswalkingwiththoselegs,andI’mnotsureifwewillseeit.Thenthis

projectjust–Imean,theydidn’tgoanyfurther.

Itislikemanyofthedesignsthatmakeuseofairpressure,onlyyouendupwithreally

limitations,alotoflimitationsontheuseof–ontheabilityoftherobottoformtasks.

Andinfactthereisalotofworktodayinthisareathatiswithartificialmusclestocreate

fastermusclesthatuseairpressure.

Andtherearemanydifferentsolutionsthatwillpushthislittlefurther,butstillyouhave

limitations,andasIsaid,wewilldiscusslittlebitmoreaboutthoseissuesofdesign,

especiallyinthecontextofsafetybecausesafetyreally,reallyisbecomingavery

importantaspectinrobotdesignbecausewehavebeenworkingwithrobot–with

[inaudible]robots.

So[inaudible]robotsareworkingaloneorworkingwithpartsandobjectsyoudon’t

reallyworrytoomuchifthereisanaccidentjustbetween–well,therobotandthat

environment.Butifyouaregoingtoworkwithhumans,youreallyhavetomakesure

thatthereisnodangertothehuman,andthatisreallyachallengingproblem,sowewill

comebacktothislater.

Anyothercommentaboutthis?

Okay.Allright,solet’sgobacktothelecture.Solast

timewesawthistoolwecallhomogeneoustransform,andthehomogeneoustransform

reallyhasseveralinterpretations,orcanfulfillseveralfunctions.

Andthefirstoneofthemisthefactthattransformationlikethisallowsustodescribethe

frame,soframeBisdescribedwiththerespectofframeAgiventhistransformation.So

ifIknowthehomogeneoustransformationbetweenBandA,thatisthisfourbyfourTMetrics

thatdescribesA–Bin–witharelationtoA.

ThenIhavedescriptionofthisframeB,andthisdescriptioncontainstherotationofthe

axisofframeBwithrespecttoA,andthelocationoftheoriginofframeBwithrespect

toframeA.Nowwesawalsothatthereisanotherrolethishomogeneoustransformation

canplay.

Andthissecondrole–thirdrole,whatever,doyouhaveanideawhatcanweusethis

transformationfor?

Whatcanwe–whatcanthistransformationhelpusdo?

Operations?

Operations,thatis–wecan[inaudible]the

transformationasanoperatorthatisactingonavectorandchangingthisvector,rotating

thev