Investigation of Practical Flight Control Systems for Small Aircraft

327 Pages·2012·8.69 MB·English

Investigation of Practical Flight
Control Systems for Small Aircraft
Wouter Falkena

Investigation of Practical Flight Control
Systems for Small Aircraft
W. Falkena
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Investigation of Practical Flight Control
Systems for Small Aircraft
PROEFSCHRIFT
terverkrijgingvandegraadvandoctor
aandeTechnischeUniversiteitDelft,
opgezagvandeRectorMagnificusprof.ir.K.C.A.M.Luyben,
voorzittervanhetCollegevoorPromoties,
inhetopenbaarteverdedigenopmaandag17december2012om12:30uur
door
WouterFALKENA
ingenieurluchtvaart-enruimtevaart
geborenteLeek.
Ditproefschriftisgoedgekeurddoordepromotor:
Prof.dr.ir.J.A.Mulder
Copromotor:
Dr.Q.P.Chu
Samenstellingpromotiecommissie:
RectorMagnificus voorzitter
Prof.dr.ir.J.A.Mulder TechnischeUniversiteitDelft,promotor
Dr.Q.P.Chu TechnischeUniversiteitDelft,copromotor
Prof.dr.ir.M.Verhaegen TechnischeUniversiteitDelft
Prof.Dr.-Ing.R.Luckner TechnischeUniversitätBerlin
Prof.Dr.-Ing.F.Holzapfel TechnischeUniversitätMünchen
Prof.Dr.-Ing.R.Reichel UniversitätStuttgart
Dr.ir.G.Looye DeutschesZentrumfürLuft-undRaumfahrt
Prof.dr.E.K.A.Gill TechnischeUniversiteitDelft,reservelid
Dr. ir. C.Borstheeftalsbegeleiderinbelangrijkemateaandetotstandkomingvan
hetproefschriftbijgedragen.
Ditproefschriftismedemogelijkgemaaktdoordefinanciëleondersteuningvanhet
EuropesezevendekaderprogrammaprojectSAFAR.
ISBN978-94-6203-258-3
ToEster,
mylove,mylife,mywife

SUMMARY
Investigation of Practical
Flight Control Systems for Small Aircraft
WouterFalkena
In the future airspace, a growth in small aircraft movements is to be expected
accordingtotheUSSmallAircraftTransportationSystem(SATS)andtheEuropean
Personal Air Transportation System (EPATS) programs. The main reason for this
growthisduetoanincreasingdemandforpeopletoaccessmorecommunitiesin
less time. With theintroductionof improved and cost-efficient technologies, it is
even expected to become an attractive alternative to road transportation. In the
generalaviationsegment,however,fatalandnon-fatalaccidentsarenotrare. Cur-
rently, an average number of seven accidents per 100,000 flight hours dominates
thissegment. Asthismarketisexpectedtogrowsignificantlyinfutureyears,mea-
suresmustbetakentoguidethisgrowthinasafemanner.
Bylookingmorecloselyataccidentanalyses,frequentcausescanbetracedback
topooraircrafthandling(72%)andpilotdecision-makingerrors(36%). Simultane-
ously performing the tasks of aircraft handling, navigation, communication, and
planningcanberatherdifficult,especiallyforless-experiencedpilots. Intermsof
aircrafthandling,misjudgingthecouplingofaircraftstates,suchastheadditional
pitchingandyawingmotionthatoccurwhentheaircraftstartstoroll, andtheef-
fectsofexternaldisturbancescanputpilotsinunsaferegionsoftheflightenvelope.
Intermsofdecision-making,ambiguousandconflictinginformationfromtheair-
bornesystemscanresultinpoorpilot“situationawareness”anddecision-making.
Toresolvetheseissues,controlaugmentationtechniquescanbeusedtocreateeasy
andsafeaircrafthandlingcharacteristicsandnewwaysofusingandpresentingin-
formationonflightdisplayscanbeexploredtoimprove“situationawareness”and
decision-making. Thisthesis,however,onlydealswithimprovingflightsafetyand
easyaircrafthandling.
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SUMMARY
Commercialaviationhasalonghistoryinusingcontrolsystemstoshapeideal
aircraftresponses. Toincreasesafety, moderncommercialaircraft, suchasaBoe-
ing 777 and an Airbus A380, are also equipped with a Flight Envelope Protection
(FEP) system to protect for stall, exceeding over-speed, limit angle of attack and
load factors. This has greatly reduced the number of handling and control acci-
dents in the commercial aviation sector. However, simply downscaling these ad-
vancedFly-By-Wire(FBW)platformsforgeneralaviationaircraftisnotanoptionas
itwouldsignificantlyincreasethecostofsuchanaircraft. Inthe“SmallAircraftFu-
tureAvionicsArchitecture”(SAFAR)program, anongoingEuropeanproject, alow
costFBWplatformwillbedevelopedforsmallaircraftbyusinga“FlexibleAvionics
PlatformApproach”. Thisapproachallowsforpotentialcostsavings,butalsointro-
duces a unique environment for the FCLs. In this environment, FCL designs are
neededthathaverobustnessagainstmodeluncertainties,sensorbias,sensornoise
and time delays, while being fast and accurate enough to accommodate the rela-
tivelyagiledynamicsofasmallaircraft. TheseFCLdesignsshouldalsobeusable
in the near future to support the safe growth of the general aviation market. FCL
designsthatmeettheserequirementsarecalledpracticalFCLdesignsinthisthesis.
Toimprovecosteffectivenessofsuchdesigns,itisbeneficialtoallowtheFCLstobe
transferredeasilytoothersmallairplanes,ideallywithoutanymodification.
WiththeuseofFEP,flyingtheaircraftcanbemademoresafe. Itdoesnotmake
flyingeasier,however.Rate-Command/Attitude-Holddecouplestheflightcontrols,
therebysimplifyingflyingtheaircraft,itrejectsturbulenceandisaprovenconcept,
usedatlowspeedsintheAirbusA320/330and340. Thereforethismanualcontrol
modeisselectedasoneofthemodesforwhichFCLdesignsarecreatedinthisthe-
sis. Asecond,automatic4Dtrajectoryfollowingmode(NAVmode)isusedforFCL
designsinthisthesisaswell.However,theemphasisliesonthemanualmode,since
aneasyhandlingFCLremainsessentialincaseofanemergencyandforthefunof
manualflying.
Based on a dynamic model of a Diamond DA 42 and a description of the dy-
namic properties of the FBW platform, two different FCL designs for each mode
have been synthesized and analyzed in this thesis. The first design uses classical
controltheory,morespecifically,loopshapingwithfocusontrackingperformance,
disturbancerejectionandnoiseattenuation. GainselectionofthisFCLisdoneus-
ingthecombinationofaroughpatternsearchmethodandatrust-region-reflective
method.ThesecondFCLdesignusesanewlydevelopednonlineardesignmethod,
basedonbackstepping,singularperturbationtheoryandapproximatedynamicin-
version. This method, called Sensor-Based Backstepping (SBB), uses no dynamic
modelinformationandreliessolelyonmeasurements.BothFCLdesignshavebeen
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