robotics - university of south carolina
TRANSCRIPT
2018
Possible Final Examination Questions
Robotics CSCE 574
1) Describethethreemainrobotarchitecturesprovidingforeachofthemanexample.
2) Definewhatmiddlewareis.
3) Showhowtwonodes(onepublisherandonesubscriber)interactwitheachotherinROS.
4) DescribethecoreelementsinROS.
5) DefineROStopics,services,andactions,andwhenismoreappropriatetouse
eachofthem.
6) Definethetermsexteroceptiveandproprioceptivesensors.Providetwoexamplesforeach.
7) Listandcomparethreedifferentrangesensorsintermsofeaseofuse,accuracy,computationalcost,andenergycost.
8) WhatarethedifferencesbetweenHydraulicdriveandShapeMemoryAlloydrive?Nameoneapplicationinwhicheachoneofthemisappropriate.
9) WhatarethedifferencesbetweenHydraulicdriveandPneumaticdrive?Nameoneapplicationinwhicheachoneofthemisappropriate.
10) WhatarethedifferencesbetweenHydraulicdriveandElectricaldrive?Name
oneapplicationinwhicheachoneofthemisappropriate.
11) WhatarethedifferencesbetweenPneumaticdriveandShapeMemoryAlloy
drive?Nameoneapplicationinwhicheachoneofthemisappropriate.
12) WhatarethedifferencesbetweenElectricaldriveandShapeMemoryAlloy
drive?Nameoneapplicationinwhicheachoneofthemisappropriate.
13) WhatarethedifferencesbetweenPneumaticdriveandElectricaldrive?Nameoneapplicationinwhicheachoneofthemisappropriate.
14) Defineforwardkinematicsandinversekinematics.
15) Foradifferentialdriverobot,wherethewheelsaredistancedapartandthe
wheelvelocitiesareVlandVr.EstimatethelinearvelocityVandtheangularvelocityω .
16) InaPIDcontrollerwithgainsKp,KiandKd:describewhichquantityeachone
ofthemiscontrolling.Describealsotheeffectsofchangingeachgain.
17) Whenaproportionalcontrollertriestofollowthestepfunction(y=1:x<0.5;
y=1.5:x>0.5)describethepossiblecausesfortheresponseshownhere:
18) Whenaproportionalcontrollertriestofollowthestepfunction(y=1:x<0.5;y=1.5:x>0.5)describethepossiblecausesfortheresponseshownhere:
19) DescribetwoproblemswithEuleranglesforrepresentingrotationsin3D:
20) Pleaseperformthefollowingmatrixmultiplication:
𝐴𝐵 = 𝑎 𝑏 𝑐𝑑 𝑒 𝑓
𝑘 𝑙𝑚 𝑛𝑜 𝑝
=
21) DefineSimultaneousLocalizationandMapping(SLAM)andexplainwhatarethemainchallenges:
22) Whatarethedifferencesbetweentopologicalandgridbasedmaps?Namean
applicationforeachone.
23) Whatarethedifferencesbetweentopologicalandfeaturebasedmaps?Name
anapplicationforeachone.
24) Whatarethedifferencesbetweenfeatureandgridbasedmaps?Nameanapplicationforeachone.
25) Describetwodifferenttypesofinaccuracythatcanresultfromusingthesonarsensor.
26) Defineandcompare“GlobalLocalization”and“Tracking”.
27) Defineandcompare“GlobalLocalization”and“KidnappedRobotProblem”.
28) Defineandcompare“KidnappedRobotProblem”and“Tracking”.
29) ForaBayesianFilter:
SimplifytheequationusingtheMarkovproperty,thetheoremoftotalprobabilityandBayesruletogetto:
30) Onemajorcomponentofthe“ParticleFilter”algorithmisresampling.Provideabriefdescription.Whatisthemaingoaloftheresamplingstep?
31) ProvideabriefdescriptionoftheParticleFilterstateestimationalgorithm.Explainhowthe:Propagate,Update,andResamplingstepswork.
i at time actions are and i at time nsobservatio are where),...,,,,|()( 0211
ii
tttttt
aooaoaoxpxBel −−−=
Bel(xt ) =ηp(ot | xt ) p(xt | xt−1,at−1)∫ Bel(xt−1)dxt−1
where:
Bayes Rule : p(a | b) = p(b | a)p(a)p(b)
you can assume :η =1/ p(oi | at−1,…,o0 )
32) Inthefollowingaparticlefilterisusedtotrackthepositionoftherobotinatwodimensionalenvironment,withnoiseintranslation(xaxis)andinlateraldrift(yaxis).Thetwopicturesidentifytwodifferentinstancesofusingsuchaparticlefilterforarobotthatgoesforwardof100cmalongthexaxis.Whyisthereadifferencebetweenthetwoinstances?
33) Assumethatthestateoftherobotisthepositionxandy.Inthefollowingpicture,depictingaparticlefilteronanenvironmentforlocalizingarobotdenotedwithanasterisk,pleasedrawtheareaswhereaftertheupdateparticleswillhavetheweightincreased.Therobotcansensethedistancefromthewallsasshowninthepicture.
34) WhatisCooperativeLocalization?
35) ForaKalmanfilterestimatorprovideasmallexplanationaboutthefollowing
equations:S=H*P*HT+R
WhereHisthemeasurementfunctionmatrixPthecovariancematrixbeforetheupdateandRisthesensorserrorcovariancematrix.
36) Foramobilerobotwhoseestimatedmotionisdescribedby:
. anditsrealmotionisdefinedas:
Derivetheerror:
usingsmallangleapproximation.
37) WhenusinganindirectEKFtheerrorinthestateofamobilerobotisdescribedbythefollowingequation:.
.
whereWiszeromeanGaussiannoise,andthecovariancePisdefinedas:
DerivetheequationofthecovarianceasafunctionofFtandGt
38) Consideravehicletravellingwithlinearvelocityvandangularvelocityωaffectedbynoisewvandwωrespectively.Therefore,themeasuredvelocitiesare:𝑣!𝜔!
=𝑣! + 𝑤!𝜔! + 𝑤!
Therealposeofthevehicleisxt=[xt,yt,θt ]T;andtheestimatedposeis𝒙𝒕 = 𝑥𝒕 𝑦𝒕 𝜃𝒕 𝑻
Providetheequationsfortimet+1fortherealpose:
tw
twVyy
twVxx
t
t
t
ttt
tVttt
tVttt
δωφφ
φδ
φδ
ω )(ˆˆ
ˆsin)(ˆˆ
ˆcos)(ˆˆ
1
1
1
++=
++=
++=
+
+
+
111 ˆ~+++ −= ttt xxx
ttVyytVxx
ttt
tttt
tttt
δωφφ
φδ
φδ
+=
+=
+=
+
+
+
1
1
1
sincos
ttttt WGXFX +=+
~~1
]~~[ 11/1Ttttt XXEP +++ =
𝒙!!! =𝑥!!!𝑦!!!𝜃!!!
=
andtheestimatedpose:
𝒙!!! =𝑥!!!𝑦!!!𝜃!!!
=
asafunctionofthepreviouspose,therealvelocities,andthenoise.
39) WhatistheiterativeKalmanFilter?
40) IntheSLAMexperimentshowninthefollowingimagedescribethereason
forthedifferenceinthelocationuncertaintybetweentheAandBlandmark
A
B
41) DefineOpticalFlow
42) Definetheapertureproblem
43) Whatisthebaselineinastereocamera?
44) Whatisthedifferencebetween“OpticalFlow”and“SceneMotion”?
45) DescribetheGeneralizedVoronoiGraph(GVG)explorationalgorithm.
Outlinethemajorsteps:
46) Foranoutdoorrobot,describeatleast3costparametersaffectingpath
planning.
47) Foranindoorrobot,describeatleast3costparametersaffectingpath
planning.
48) DefinethetermsC-Space(configuration),FreeSpace,Semi-FreeSpace,andC-Obstaclespace.Whenaretwopathshomotopic?
49) Describethedifferencesbetweenthe“ProbabilisticRoadmap”(PRM)andthe“RapidlyExploringRandomTree”(RRT)pathplanners:
50) Whatistheguidingprinciplesbehind:a)visibilitygraphandb)generalizedVoronoigraphpathplanningalgorithms?Whatisthemajordifferencebetweenthetwoalgorithms?
51) FortheBug2algorithmwhatistheminimumsetofsensorsneeded.
52) Definethemainideabehindpotentialfieldpathplanning.Whatisitsmaindisadvantage?Describethemostcommontechniquetoovercomeit:
53) Foratwo-linkmanipulator,withtworevolutejoints,eachrotating[0,360]degrees,whatistheconfigurationspace.Drawarepresentation.
54) Whataretheadvantages/disadvantagesofmulti-robotsystems?
55) Describetwodifferentstrategiesformulti-robotformation.
56) DefineMarsupialRobots.
57) DescribetheAuctionmechanismfortaskdistributioninmulti-robotsystems.
58) DrawtheReebgraphandaplausibleoptimalorderofcellcoverageforthefollowingenvironment.Hint:Remembertodoublecertainedges.Startposition:topleftcorner.
59) UsetheWavefrontplanneronthefollowingworld,startingat“0”:
0
60) Usingthepinholecameramodelderivetherelationshipbetween(x,y)and(X,Y,Z).
x=
y=
61) DrawthepathusedbytheBug1algorithmfromStarttoGoal.
Start
Goal
62) DrawthetrajectoryfortheBug2pathplanningalgorithm,startingposition
therobotgoalthestar.Consideraleftturningrobot.
63) Drawthevisibilitygraphinthefollowingenvironment.Drawalsothe
shortestpaththroughthevisibilitygraphfromStarttoGoal.
Start
Goal
64) DescribetheFrontierbasedexplorationalgorithm.
65) Discussthedilemmabetweenexploitation(localization)andexplorationof
newterritoryinanyexplorationandmappingalgorithm.Inparticular,consideraccuracyandefficiency.
66) Whatisthedifferencebetweendeterministicandrandomcoveragealgorithms?Giveanexampleofanapplicationwhicheachtypeismoresuitedforandjustifyyourselection.
67) Usethegrassfiretransformtocreatetheconfigurationspaceonthefollowingworld,dilatingtheobstaclesby2pixel.Istheresultingspaceconnected?