Download pdf - 2015 01 27 Comms Doc for Teams Release 2

CommunicationsbetweenOperatorand

RobotfortheDRCFinals

Release2onJanuary27,2015.DISTARCase23912

RevisionHistory1 Introduction2 OverviewoftheDRCFinalsCommsSystem

2.1FieldComputers2.1.1PowerforComputers2.1.2FieldComputerConnectors

2.2CloudServices3WirelessLinktoRobot

3.1WirelessRadioSelection3.2AntennaSelection3.3AntennaMounting3.4OperatingFrequencies3.5RadioConfiguration3.6WiredWirelessConnection3.7RestrictionsandLimitations

3.7.1ThroughputRestrictions3.7.2PacketLoss3.7.3UDP/TCP3.7.4DisallowedTechnology

4CommunicationsbetweenRobotandOperator4.1LinkProperties4.2IPVersion,IPaddresses,Subnets,Ports,andPacketSize4.3PhysicalConnections4.4SequesteredOperators

5WiredConnectors6CommunicationsforEmergencyStops7SimpleExample

ApprovedforPublicRelease,DistributionUnlimited 1

RevisionHistoryThissectioncapturesmajorchangestothisdocument.

Date Section Description

11/30/2014 Document Release1

1/27/2015 DocumentDocumentFigure1

Release2IncreasednumberofLink3ports.Changed1023to2047threeplacesintext,andonceinFigure1Changed6384to16384tocorrecttypographicerror

1 IntroductionThecommunications(comms)infrastructurenowbeingcreatedfortheDARPARoboticChallenge(DRC)Finalshasbeendesignedwithtwoprimarygoals:reliabilityandtheencouragementofrobotautonomy. ReliabilityisbeingaddressedbypreassemblingtheFinalsinfrastructureatatheSPAWARSystemsCenterAtlantic(SSCLANT)facilityinSouthCarolinaandallowingteamstotestendtoendcommsatthisfacilityusingtheirownrobotortheirownsurrogatesystem.Inaddition,DARPAwillsupplyallteamsqualifiedtocompeteintheFinalswithpreconfiguredradioequipmentthatisknowntobecompatiblewithDRCFinalscommsinfrastructure.Teamswillberequiredtousetheseradiosandonlytheseradios.Radios,antennas,androbotestopswillbeprovidedbyMarch1,2015toallqualifiedteams.DARPAconsidersthatautonomycanbegaugedbyhowmuch,andhowquicklydataneedstobeexchangedbetweenahumanoperatorandarobotinordertoexecuteagiventask.Whenperformingaparticulartaskinaspecifiedtime,thefewerbitsexchanged,thegreaterthedemonstratedautonomy.TopromoteautonomyDARPAwillcreatecontrollednetworkserviceinterruptionswithsubstantialdurationinwhichonlylowdataratecommunicationbetweenhumansandrobotswillbepossible.Theblackoutswillbestructuredsothatteamswithmoreautonomoussystemswillbeabletoprogressthrougharunmorequickly.However,therewillalsobesufficientdataexchangeduringsomeperiodssothatteamswithlessautonomywillbeabletoperformsometaskssuccessfully,albeitmoreslowly.Notethatteamsthatscorethesamenumberofpointsforsuccessfullycompletingtaskswillberankedonhowquicklytheycompletedthesetasks.(SeeSection7,RulesoftheDRCFinals.)


InasignificantchangefromtheDRCTrialsofDecember2013,allrobotswillbeuntetheredattheDRCFinalsinJune2015.Thismeanstherewillbenobelays,nopowercables,andallcommstotherobotwilltraveloverwirelesslinksprovidedbytheDARPAsuppliedradios.

2 OverviewoftheDRCFinalsCommsSystemFigure1showsasimplifiedlogicaldiagramofkeycommunicationslinks.ThediagramshowstheRobotatthetop,awirelesslinkbelowthat,theFieldComputerinthemiddle,theDegradedCommunicationsEmulatorbelowthat,andtheOperatorControlStation(OCS)atthebottom.ItemsshowningreenwillbesuppliedattheFinalsbyDARPA.

2.1FieldComputersTheFieldComputerisanoptionalcomputer(ormultiplecomputers)thatteamsusetoprocessdata,forexample,streamsofimagesforvisualodometry.TheFieldComputerservesasasurrogateforthevastlyimprovedcomputersthatareexpectedtobeavailableinthefutureandthatcouldbebuiltintofuturedisasterresponserobots.TeamswillnotberewardedorpunishedforusingFieldComputer(s).

2.1.1PowerforComputersTeamswillhaveatotaloutofthewallpowerbudgetforcomputingof8KW,whichwillbeprovidedbyfour(4)twenty(20)Ampere110Vcircuits.ThisbudgetissharedbyanyFieldComputersandOperatorControlStations.(Inaddition,DARPAwillprovideaseparatecircuitforoperatingandchargingrobots.)DARPAnetworkingsystemswillnotsupportPoweroverEthernet(PoE).

2.1.2FieldComputerConnectorsTheFieldComputer(s)shallconnectviaCAT5CopperTwistedPairGigabitEthernetusingRJ45connectors.2.1.3 Field Computer Location and Access FieldComputerswillbeoperatedinadedicatedroomsuppliedbyDARPAthatisremotefromtheteamgarages.TeamswillhaveaccesstothisroomtoservicetheirFieldComputers.

2.2CloudServicesApprovedforPublicRelease,DistributionUnlimited 3

Thecloudservices,connectedtotheOperatorControlStationbyaVirtualPrivateNetwork(VPN)DARPA,providedareoptionalandmaybeusedforincreasedcomputingpowerandstorage.Thedataratetothecloudserviceswillbe50Mbit/secineachdirection.

Figure1.SimplifiedLogicalCommunicationsDiagram.Thecommunicationslinks(asnumberedinthisfigure)aredescribedinthefollowingsections.

3WirelessLinktoRobot


RobotswillcommunicatewiththeiroperatorsbidirectionallyoverwirelessLink1inFigure1tobesuppliedbyDARPA.DARPAwillsupplyteamsthathavequalifiedfortheDRCFinalswithradios,eachwithawiredEthernetinterfacebyMarch1,2015.DARPAexpectsthewirelesscommunicationlinktoprovide300Mbit/sec(Megabitspersecond)ofbandwidth.Tomaximizethroughput,teamsshouldavoidsendingsmallpacketsandselfregulatepacketratesinbothdirections.DARPAsradioswilldiscardexcesspackets.Thewirelesslinkwillhavegreaterpacketlossthanawiredconnection.Teamsshouldplanforapproximately210%packetloss.DARPAwillnotintentionallydegradethewirelesslink.

3.1WirelessRadioSelectionTheNetgearR7000(3x3MIMO)platform,utilizingDDWRTsoftwarewithDARPAspecificconfigurationswillbetheradiousedforDRCfinals.TheradiosboughtandsuppliedbyDARPAaretheofficialradios.Otherradios,eventhosebythesamemanufacturerandthesamemodelnumber,arenotsupportedandmaynotworkasintended.

3.2AntennaSelectionTherewillbe3wirelessdataradioflexiblerubberduckantennasontherobotthatwillbeprovidedbyDARPA.Theseantennasprovideanomnidirectionalsignal,stockSMAconnectorsforradioantennaleads,acceptablesizeandweight,andoptimalworkingrange.

3.3AntennaMountingTeamsarefreetomounttheradioandantennasontherobotastheyseefit,includingthepossibilityofseparatingtheantennasfromtheradioforbetterantennaplacement.IfateamdesirestoremovetheantennasfromtheradioDARPAwillprovidethree(3)threefootRFcablestoaccommodateseparatingtherobotradiofromtheantennas.Routingofthecablewillrequireaminimumbenddiameterofatleastsix(6)inchesforallantennacablechangesofdirection.Longercablescanlikelybeaccommodated,butDARPAtestingwillfocusonantennasdirectlyconnectedtotheradioandwiththeantennasconnectedutilizingtheDARPAsuppliedthreefootRFcables.Whenmountingtheantennas,teamsshouldconsiderthefollowing:

OcclusionDuringtesting,metalobstructions(i.e.arobotshead)betweentheradiopair

willvastlyreducetheachievablethroughput


ParticipantsshouldconsiderachievingaclearlineofsighttotheantennasbetweenanAccessPointandclientantennas

Participantscanassumea20upwardanglefromtherobottotheDARPAsupplied

AccessPointTherangeofmotionoftheirrobot

Antennasdislodgedduringarunarenoteligibleforrepairbyapersonuntiltherunconcludes.

Possibleimpactzonesintheeventofafall

3.4OperatingFrequencies

ConfigurationType Setting

FrequencyBand 5GHz

ChannelWidth 80MHz

ChannelNumber(Frequency) 36(5.180GHz),132(5.680GHz),52(5.260GHz),149(5.745GHz)

3.5RadioConfigurationTheconnectionusedtoestablishnetworkconnectivitybetweentheclientandserverwirelessradiosisknownasawirelessclientbridge.Theserverradio(fixedsite,i.e.locatedon/nearthetestcourse)willbeconfiguredinAccessPointmodeandtheclientradio(Robotmounted)willbeconfiguredforClientBridgemode.(SeeFigure1.)DARPAwillprovideonepairofpreconfiguredradiostoeachparticipant(team)fortestingattheirhomelocationpriortotheDRCFinals.TheAccessPointusedduringDRCFinalsonthetestcourseswillbeinstalledandconfiguredbyDARPA.TheAccessPointusedintheteamsprivategarageareaforpracticewillbetheoneprovidedbyDARPAfortheteamsuseattheirhomesitepriortoarrivingatDRCFinals.TeamsmustusetheprovidedrobotmountedclientradioforDRCFinalsbothinthegarageandwhenonthetestcourse.WhenateamisactiveontheDRCFinalscoursetheyarerequiredtoutilizetheDARPAinstalledAccessPointon/nearthetestcourselocation.Asaresult,allparticipantsarerequiredtoutilizethepreconfiguredsoftwareandconfigurations.NOparticipantshallmakechangestotheDARPAprovidedconfigurations.DARPAisnotresponsiblefor


incompatibleradiopairingduetoanyunauthorizedsoftwareorconfigurationchangesmadebyaparticipant.DARPAreservestherighttoreloadsoftwareandconfigurationsonanyradioatanytimeforanyreason.PriortoaparticipantmovingfromthegarageareaontotheDRCFinalscourse,DARPAwillrequireanetworkcheckouttoconfirmconnectivitybetweentheoperatorandrobotviatheDARPAnetwork.Moreinformationregardingthenetworkcheckoutwillbeprovidedatalaterdate.DARPAwillprovideaconfigurationfilewitheachradiopairalongwithinstructionsonhowtoloadtheconfigurationfileintheeventtheradiorequiresafactorydefaultreset.

3.6WiredWirelessConnectionDARPAwillsupplythree(3)twentyfootlongRFcablesandproperattenuators.ThesecomponentswillallowthewirelessradiomountedontherobotandtheDARPAprovidedwirelessAccessPointradio(providedtoallowtestingwhileattheteamshomelocation)tobehardwiredtogether.Thishardwiringisdonetoallowafullsystemtest(minusonlytheradioantennas)withouthavingtodealwithuncontrollablewirelessinterference.Teamswillberequiredtouseahardwiredapproachforfullsystemtestinginthegarage.

3.7RestrictionsandLimitations3.7.1ThroughputRestrictionsDARPAwillinstallthroughputlimitsof300Mbit/secondataflowingtoandfromtherobot.(I.e.datatheRobotistransmittingoverthewirelesslink+datatheRobotisreceivingoverthewirelesslink)300Mbit/sec.)DARPAhasnopositiononwhatsizepacketsateamchoosestoutilizesolongasMTU=1500.3.7.2PacketLossTherewillbepacketsdroppedduetotheinclusionofthewirelesslinkintothenetwork.Nowirelessnetworkisasreliableasawirednetwork.DARPAsuggeststhatteamsbepreparedtoaddresspacketlossinthe210%range,toandfromtherobot.Antennaplacement,highmobility,andotherteam/robotissuesaffectboththroughputandlosscharacteristicsofwirelessnetworksandarethesoleresponsibilityoftheteams.ThispacketlossisnotpartoftheintentionalcommunicationoutagesthatDARPAwillbeimposingduringruns.


3.7.3UDP/TCPDARPAhasnopositiononUDPversusTCPandtheteamsarefreetoutilizeeitheroracombinationofbothwhereappropriate.However,allthroughputresultsandalltestingwasconductedutilizingUDPandDARPAsspecificationsforthroughputonlyapplytoUDP.3.7.4DisallowedTechnologySinceDRCFinalsisleveragingwirelesstechnologyasthenetworkingbackbonebetweentheoperatorsandtherobotsviathe5GHzband,wearerequiringthatnoteamsactivate5GHzAccessPointsor[J3]anyothertransmitter/receiverofanykindwhileatthecompetition.DARPAwillbeactivelyscanningfor5GHztransmittersatthecoursesandinthegarages.Inadditionteamsmaynotusetheirown2.4GHzaccesspoints.Whenrunsaretakingplaceteamswillnotbeallowedtouseany2.4GHZnetworks.Whenrunsarenottakingplace,DARPAwillprovidea2.4GHzlinktotheInternet.

4CommunicationsbetweenRobotandOperator

4.1LinkPropertiesLink1inFigure1isthewirelesslinktoandfromtherobot.TheOperatorControlStation(OCS)communicateswiththeRobot(possiblythroughaFieldComputer)throughLink2andLink3inFigure1bywayofaDegradedCommunicationsEmulator(DCE).TheDCEwillemulatesignallossthatmightoccurduetopoorRFsignalpenetrationthroughwalls.Link2isunidirectionalandcarriesdatafromtherobottotheOCS.Dataonthislinkwilluseports16384to24575.Becauseitisunidirectional,Link2cannotbeusedforTCP.Link2willoperateintwomodes:whiletherobotisattemptingTasks1,2,3,9,and10,link2willsupportabout300Mbit/secofdata.Link2willhaveminimallatencytotheOCS.Atallothertimes,Link2willprovideonesecondburstsofdataatapproximately300Mbits/sec,interspersedwithblackoutsofvaryinglengths.Thelengthoftheblackoutswillbebetween1and30seconds.


Figure1showsthesignallossemulatorasaSinglePole,SingleThrow(SPST)switch.Whentheswitchisopen,nodataflowsandthereisablackout.Whentheswitchisclosedaonesecondburstofdataistransmittedat300Mbit/sec.Atthestartofarunnoblackoutswilllastmorethan30seconds.Theaveragelengthofblackoutswilldecreaseduringthecourseofarun.Atabout50minutesintoarun,blackoutswillnolongeroccur.PacketsheldbytheDCEatthestartofablackoutwillbediscardedpacketsreceivedbytheDCEduringblackoutwillbediscarded.Theblackoutscheduleforagivendaywillbemadeavailabletoteamsthepreviousday.Thesameschedulewillbeusedonallcoursesandforallrunsthroughagivenday.Theschedulemaychangefromdaytoday.Link3isanalwaysonbidirectionallinkbetweentheOCSandtherobot.Link3willhaveaconstantdatarate(tobedetermined)between9600bit/secand2,000bit/secandwillsupportTCPandUDP.Link3willalsocarrybidirectionaltrafficforInternetControlMessageProtocol(ICMP)andwillhaveathroughputof4800bit/s.Dataonthislinkwilluseports0to2047.Link3willbethedefaultroute.Link4isaDARPAprovidedVirtualPrivateNetwork(VPN)connectiontooptionalcloudcomputingresourcesavailabletoteams.Thelinksupports50Mbit/secdataratesineachdirection.

4.2IPVersion,IPaddresses,Subnets,Ports,andPacketSize

TeamswilluseIPV4forallcommunicationsusingtheDARPAinfrastructure.IPV6willnotbesupported.TeamswillusethefollowingconventionforIPaddresses:Eachteamwillbeassignedanidentificationnumber,N,between1and30.TeamNisassigned10.N.y.xasitssubnetsfortheentirecompetition.10.N.1.xisthesubnetthatteamNwilluseforitsOCUcomputer(s).10.N.2.xisthesubnetthatteamNwilluseforitsFieldcomputer(s).10.N.3.xisthesubnetthatteamNwilluseforitsRobotcomputer(s).Ports12047willspecifythatLink3(Bidirectional20009600bit/sec)willbeusedforaparticularmessage.


Ports1638424575willspecifythatLink2(Unidirectional300Mbit/sec)willbeusedforaparticularmessage.TheIPaddresssettingsneedtoshowtheIPPrefixlengthswhichwillbe/24.Packetsizeislimited:theMaximumTransmissionUnit(MTU)is1500.Jumbopacketsarenotallowed.

4.3PhysicalConnectionsPhysicalconnectionsbetweenanyfieldcomputers,theOCS,andtheDARPAnetworkwillbemadebymaleRJ45cablessuppliedbyDARPAWhentherobotisinthegarageitalsocanbeconnectedtotheDARPAnetworkwithamaleRJ45cable.TeamsareencouragedtomakeuseoftheDARPAnetworktoassurethatanynetworkingproblemsareresolvedquickly.

4.4SequesteredOperatorsOperatorswillbesequestered.Atnotimemayanyoftheoperatorsreceiveinformationfromanyoneoranythingviewingtherobot.DARPAwillhaveobserversattheFinalstomonitorcompliance.

5WiredConnectorsIntheunlikelyeventofawirelesscommunicationsfailureintheDARPAinfrastructure,DARPArequiresthatteamsbepreparedtousewiredcommsconnectionsbetweenrobotsandFieldComputers(ifpresent)orOperatorControlStations(ifthereisnoFieldComputer).DARPAwillsupplythecables,butteamsmustsupplyfemaleRJ45connectorsmountedontheirrobots.Sincetheremaybesignificanttensiononsuchcables,teamsshouldprovidestrainreliefmechanismstoreducethechanceofdamagetotheirRJ45connectors.

6CommunicationsforEmergencyStopsByMarch1,2015,DARPAwillsupplyawirelessemergencystopsystemtoteamsthathavequalifiedfortheDRCFinals.TheeStopissuppliedbyHRIseeappendicesAandB.TeamsmustusethisestopduringFinals.


TeamsmustintegratethissystemontheirrobotsanddemonstrateitsfunctionalitybeforetheymaycompeteintheDRCFinals.

7SimpleExampleAsahypotheticalexample,assumethatTeam5wantstosendacommandtotheirrobottomoveitsarm.Team5wantstoreceiveasimplecommandofsuccessoncompletebacktotheOCSfromtheFieldComputer.Italsowantstoreceiveavideofromoneofthecameraswhilethearmisinmotion.Team5isassigned10.5.x.xasitsteam'ssubnetsfortheentirecompetition.10.5.1.xisthesubnetthatTeam5willuseforitsOCScomputer/computers.10.5.2.xisthesubnetthatTeam5willuseforitsFieldcomputer/computers.10.5.3.xisthesubnetthatTeam5willuseforitsRobotcomputer/computers.Letssayinordertogettherobotsarmtomove,someprocessingmustbedoneonthefieldcomputer.Letsalsosayinordertogettherobotsarmtomove,theOCSneedstosendacommandtotheFieldComputertostarttheprocessing.Step1:Team5sendsacommandonport23fromtheOCS(10.5.1.12)totheFieldComputer(10.5.2.32)Sincethisportisinthelowbandwidthrange(02047),itwilluseLink3inordertogettotheFieldComputer. Step2:Afterprocessingthecommands,theFieldComputerwouldthensendthecommandsneededtotheRobot(10.5.3.54)Step3:Robotcompletesthearmmotion.Duringthistime,therobotiscapturingvideothatitistryingtosendbacktotheOCS.Inordertoreceivequalityvideo,itwouldwanttouseLink2toretrievethevideo.Toaccomplishthis,therobotwouldneedtouseahigherportnumbersomewhereintherangeof(16384424575)sothattrafficissentcorrectlybacktotheOCSifLink2isturnedon.Iftherobotis'inside'(seeRulesofDRCFinals,section6fordefinitionofinsidevsoutside)thevideomaynotarriveduetoLink2beingturnedoff.Step4:RobotsendscompletionnoticebacktoOCS.Thiscouldbeaccomplishedbysendingoverasmallerportsuchastelnet(port23)


ThiswillguaranteearrivalduethetrafficflowingbackoverLink3totheOCSattheslowerdatarate.
