Investigation of Practical Flight Control Systems for Small Aircraft PDF
Preview Investigation of Practical Flight Control Systems for Small Aircraft
Investigation of Practical Flight Control Systems for Small Aircraft Wouter Falkena Investigation of Practical Flight Control Systems for Small Aircraft W. Falkena Coverphoto©2012byMr.Pfaffstaller,DiamondAircraftIndustriesGmbH. PrintedbyWöhrmannPrintService,Zutphen,TheNetherlands. TypesetbytheauthorwiththeLATEXDocumentSystem. Copyright © 2012 by W. Falkena. All rights reserved. No part of the material pro- tectedbythiscopyrightnoticemaybereproducedorutilizedinanyformorbyany means, electronicormechanical, includingphotocopying, recordingorbyanyin- formationstorageandretrievalsystem,withoutpriorpermissionoftheauthor. 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. vii 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 viii
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