RASCAL 直升机设计与测试的控制律研究.docx

RASCAL 直升机设计与测试的控制律研究.docx

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RASCAL直升机设计与测试的控制律研究

RASCAL设计与测试的控制律研究

Abstract

设计了两种独特的控制律,在军队/NASARotorcraftAircrewSystemsConceptsAirborneLaboratory（RASCAL）的JUH-60A黑鹰上测试,第一套控制系统使用简单的速度反馈,来促进RASCAL的飞行控制系统的第一次和后来的飞行品质,第二套系统由更复杂的模型跟随结构所组成,两套系统都得以广泛的发展和测试,采用’’台式机到飞行”,分析,仿真工具,飞行测试与模型预测的响应很吻合,提供了证据与自信来发展未来RASCAL的飞行控制系统将是有效和精确的.

Introduction

本文描述了RASCAL的两套控制系统,一套的特征是响应反馈,一套是模型跟踪,

RASCAL是一种SikorskyJUH-60A黑鹰直升机,改装后用于研究,加装了一套可编程,高带宽,full-authority的研究飞行控制系统,改装内容包括平行液压作动器,高性能飞行控制计算机,通过传递系统使安全驾驶员把控制作用与有线飞行系统传递,右座副驾驶员的位置（周期变距驾驶杆,踏板等）得以移除,代之以侧向三轴控制器,以及电子总距控制驾驶杆,RASCAL配置的主要细节可参考文献1.

RASCAL由军方与NASA共同研发,是一种高度灵活的平台,可用于探索宽范围的飞行控制,战场演示,相关系统配置,飞行控制的研究能力是由一系列桌面与地面仿真工具,所支持的,以确保新概念的高效,快速和安全飞行测试,RASCAL还可以被当作一种变稳定的飞行模拟器,文中所述模型跟踪控制律很适合于此.

飞行控制发展过程

台式电脑到飞行发展环境

TheArmy/NASARotorcraftDivisionhas

developedasetofsoftwaretoolsenablingdesignerstotakeaflightcontrolconceptfrominceptiontoflighttestinanefficientandreliableprocess.Thefirststepintheprocessistheselectionofamathmodeloftheaircraftdynamics.Inthecaseof

RASCAL,6-degree-of-freedom（DOF）and10-DOFlinearmodelsoftheunaugmentedUH-60atavarietyofflightconditionshavebeenpreviouslyidentified2fromflighttestdatausingtheComprehensiveIdentificationfromFrequencyResponses（CIFER?

3）software.In

addition,avalidatednon-linearreal-timesimulationcode（GenHel）isavailable,4enablingtherobustnessofacontrolsystemdesigntobesubsequentlyevaluated

throughouttheentireflightenvelope.

军队/NASARotorcraft分部发展了一系列工具软件,来使得设计者的飞行控制构想可以从起初到飞行测试得以有效和可靠的实现,第一步是选择飞行器动力学的数学模型,在RASCAL,UH-60在各种飞行条件下的未放大的六自由度和10自由度的线化模型被预先辩识,使用频率响应的综合辩识软件,来源于飞行测试数据.另外一种已经验证过的非线性实时模拟程序被应用,使得控制系统设计的鲁棒性能可以在整个飞行包线内得以评估.

ControlloopsarethendesignedaroundthelinearmathmodelusingtheMATLAB/Simulink?

ControlsystemmodelingtoolsandtheControlDesigner’sUnifiedInterface（CONDUIT?

）analysis/optimizationenvironment.5CONDUIT?

isusedtoevaluateandoptimizethecontrollawgainstosimultaneouslymeetabroadvarietyofstability,performance,andhandlingqualityspecifications,aswellascertainhardware

limitationssuchasactuatorratecapabilities.

使用MATLAB/Simulink控制系统模型工具和控制设计统一分析优化环境来设计控制回路,CONDUIT被使用于评估和优化控制律增益,同时适合宽泛的稳定性,性能要求,操纵能力,以及如作动器速率等硬件限制的变化,

Theresultingclosed-loopmodelsmaybeflownina

workstation-based,real-time,pilotedsimulation（the

Real-timeInteractivePrototypeTechnology

Integration/DevelopmentEnvironment,RIPTIDE）to

evaluatequalitativeaspectssuchascontrolsensitivity

andcontrolmodetransitions.6TheRIPTIDEfacilityat

NASAAmesisequippedwithapanoramicprojection

displaysystemandanelectromechanicalbackdriven

cycliccontrollertoprovideadditionalfidelitytothis

otherwiselow-costfixed-basepilotedsimulationtool.

结果的闭环模型放入一个基于工作站的实时,用模拟驾驶（实时交互技术,集成/研发的环境）来评估性能,比如控制敏度,控制模式转换,RIPTIDE设施装备有全景的目标展示系统和机械电子的变距控制器,来提供更多的仿真度给这个低费用,固定驾驶模拟器.

Finalcheckoutandpilotfamiliarizationwiththe

controllawsisaccomplishedusingtheRASCAL

DevelopmentFacility’shardware-in-the-loop

simulator,7whichincludestheflightcontrolcomputer,

evaluationpilotinterface,andhigh-fidelityreal-time

non-linearsimulationsoftheRASCALresearchflight

controlactuators,sensors,andUH-60dynamics.

最终的检查和驾驶员熟悉控制律已经完成,使用RASCAL的人在回路设备,包括飞行控制计算机,评估驾驶界面,RASCAL研究的飞行控制作动器,传感器和UH-60动力学的高仿真度,实时非线性模拟.

Priortoapprovaloftheflightcontrolsoftwarefor

releasetotheaircraft,itundergoesacontrolledtestand

evaluationsequenceintheDevelopmentFacility（DF）,

afterwhichitisloadedintotheaircraft’sflightcontrol

computer.Oncethebasicfunctionalityofthesoftware

hasbeencheckedinflight,theflightcontrollawsare

validatedbyrecordingclosed-looppiloteddoublets

and/orfrequencysweeps.Theseflighttestdataarethen

analyzedusingCIFER?

toextractfrequencyresponses.

Theflighttesttimehistoriesandfrequencyresponses

canthenbecomparedtotheresponsespredictedbythe

simulationmodel.

预先批准把飞行控制软件准用于飞行器,在DevelopmentFacility（DF）,经历了一个控制测试和评估顺序,然后才安装入飞机的飞行控制计算机,一旦软件的基本功能在飞行中得到检查,飞行控制律得以验证通过记录的闭环或扫频,然后用CIFER软件来分析这些数据,提取出频率响应,然后可以把飞行测试中的时间历程和频率响应和之前模拟模型的作比较.

RASCAListhefirstin-houseArmy/NASA

programtoutilizethefullsuiteofdesktop-to-flight

tools.However,theprecedingdescriptionofthe

desktop-to-flightprocesshasbeenprovenoutinseveral

recentflightvehicledevelopmentactivitiesconducted

withindustrypartners,includingtheKamanAerospace

Broad-areaUnmannedResponsiveResupply

Operations（BURRO）6000-lbunmannedhelicopter,8

theNorthrop-Grumman/SchweitzerFireScoutVertical

Take-offUnmannedAerialVehicle（VTUAV）,9andthe

MicrocraftiStar9-inchdiameterunmannedvehicle.10

RASCAL是首个军队/NASA的室内项目,利用整套桌面到飞行的工具,然而,前述桌面到飞行过程,最近已经由工业伙伴所承担的的几个飞行器发展活动所证明是合适的,包括BURRO6000-lb无人直升机,诺斯-格鲁曼垂直起飞无人飞行器,微航-9英寸,无人机.

RASCALFlightControlComputer

TheRASCALResearchFlightControlComputer

Assembly（RFCCA）isdividedintotwophysically

segregatedelements:

aFlightControlComputer（FCC）

andaServoControlUnit（SCU）.Thisarchitecture

allowsagreatdealoffreedominthedevelopmentand

testingofnewflightcontrollaws,whileprotectingthe

aircraftandsystemsfromanyunforeseenanomaliesin

thosecontrollaws,orinsystemoperation.Asummary

oftheRFCCAisprovidedhere,whilegreaterdetailis

availableinRef.1.

RASCAL飞行控制计算机

RASCAL研究飞行控制计算机组合（RFCCA）包括两个隔离的物理单元:

飞行控制计算机（FCC）

伺服控制单元（SCU）.这种结构在发展和测试新飞行控制律时,允许许多空间自由,从而在控制律或者系统操作发生未料的异常情况下可以保护飞行器和系统,RFCCA的总结提供于此,其它细节可参考文献1.

TheSCUisadualizedsystemthatcomprisesthe

RFCCA’sinterfacetotheaircraftandisresponsiblefor

monitoringtheRFCSforsafeoperation.TheSCU

operateswiththeassumptionthatahardwarefailure,

sensorfailureorflightcontrollawfailurecouldoccurat

anytime,andcontinuouslymonitorsawidevarietyof

parameters.TheSCU’smonitoringsoftwaredetects

andcapturesfailuresthatwouldgenerateunacceptably

largeflightcontroltransients,andinsuchanevent

revertstheaircrafttosafetypilotcontrolinlessthan

100ms.Thedesigncriteriaforthemonitorswere

establishedthroughpilotedsimulationresearch

conductedatAmesusingtheVerticalMotion

Simulator;detailsmaybefoundinRef.11.Functional

testing,fine-tuning,andvalidationofthemonitorswas

accomplishedintheRASCALDFaswellasonthe

aircraft.

SCU是一种双核系统,把RFCCA的界面整合入飞机,负责监控RFCS的安全操作,SCU的操作假定硬件失效,传感器失效,或者飞行控制律失效,会在任何时间发生,持续监控大量的参数.SCU的监控软件察觉和捕获失效,将产生不可接受的大的飞行控制瞬变,在这样的事件中.不到100毫秒内,恢复到安全的驾驶控制状态,监控的设计标准是通过驾驶模拟研究建立的,在Ames使用竖向机动模拟,细节可参考文献11,功能测试,以及监控的批准都是在RASCALDF与飞机上完成的.

TheFCChoststheflightcontrollawcode.The

FCCisasingle-channelsystem.Abasicsetofsoftware

elementsprovidesastandardizedinterfacetosensor

data,pilotinputsandaircraftactuatoroutputsfor

implementationofflightcontrollaws.Thisallowsthe

flightcontrollawdevelopmenttotakeplaceatahigh

level,withoutrequiringknowledgeofthe

implementationdetailsofeachsysteminterface.For

example,commandsgeneratedbytheFCCarein“pilot

axes”,i.e.inchesofequivalentUH-60inceptor

displacement,whichtheSCUtranslatesthrougha

softwarerepresentationoftheBlackHawk’s

mechanicalmixingboxinto“servoaxes”,i.e.inchesof

displacementoftheforward,aftandlateralresearch

servosdrivingtheUH-60primaryservos（andinturn

theswashplate）aswellasthetailresearchservothat

drivesthetailrotorprimaryservo.Becausethe

translationfrompilotaxestoservoaxesishandledin

theSCU,itistransparenttotheflightcontrol

developer,whoneedsonlytobeconcernedwith

producingcontrollawcommandsin“pilotaxes”.

FCC是飞行控制律程序的主机,是一个单通道的系统,基本的软件单元提供传感数据标准的界面,驾驶输入和飞机输出来实现飞行控制律,这就使得飞行控制律可以发展到一个很高的阶,不需要每个系统界面的实现所需要的细节知识.比如,由FCC产生的命令在驾驶轴,也就是,离初始位移几英寸的距离,SCU通过表示飞机机械特性的软件把驾驶轴转换为伺服轴,也就是,朝前几英寸,尾部和侧向的研究伺服驾驶UH-60主要的伺服机构,与尾部研究伺服驾驶尾旋转主要伺服一样,因为把驾驶轴转换为伺服轴是需要提交SCU完成,很显然,对于飞行控制的发展,只需要考虑驾驶轴中的过程控制律,

BaselineControlLawDevelopment

Aninitialsetofcontrollawswasdesignedexpressly

forthefirstflightandsystemqualificationphaseofthe

RASCALRFCS.These“baseline”controllawswere

intentionallysimple,consistingofonlytheminimum

elementsneededtoprovidebasicstabilityaugmentation

inamannercompatiblewiththeRASCALsidestick

inceptor.Therationaleforusingsimplecontrollaws

fortheearliestworkontheaircraftwasthatany

anomalousbehavioroftheoverallRFCSwouldbe

easiertoidentify,andcomparisonoftheaircraft

responsetothatofthesimulationmodelwouldbemore

straightforward.

基线控制律研究.

初始的控制律设计明确是为RASCALRFCS首次飞行和系统限制阶段,,这些基线控制律是有意简化,由最小单元组成,需要提供基本稳定放大,采用一种和RASCAL边初始兼容的方式,使用简单控制律进行飞行器的早期工作的基本原理是RFCS任何异常行为能够容易被识别,比较飞机的响应和模拟模型也会更直接简单.

Thebaselinecontrollawsthereforeincludedonly

ratefeedbackstopitch,rollandyaw;collectivewas

“direct-drive”fromtheRASCALinceptor.Low-gain

integratorsinpitch,rollandyawprovidedtrimfollowup,

whichslowlytrimmedthesidesticktocenter

positionastheaircrafttrimstatevariedwithflight

condition.Synchronizationofthecontrollawoutput

withthesafetypilotcontrolswasprovidedtoprevent

transientbehaviorattheinstantofRFCSengagement.

Figure2illustratesthearchitectureofthepitchchannel,

whichisrepresentativeoftherollandyawaxes.whichisrepresentativeoftherollandyawaxes

基线控制律因此仅包括俯仰,滚转,偏航的速度反馈,总距是从RASCALinceptor开始的”直接驾驶”,采用低增益积分器对俯仰,滚转,偏航,提供剪裁,慢慢的从边到中间位置,当飞机裁剪状态随着飞行条件而变化,安全驾驶控制与控制律输出的同步性,在RFCS的瞬间,提供了瞬态行为的阻止,图2说明了俯仰通道的组成,同样代表了滚转,偏航通道.

Thecontrollawsincludedlimitersonauthority,

rate,andthetrimintegration;theratelimits,aswellas

mostsystemgains,weremanuallyadjustablein-flight

viatheRASCALcockpit’sControl/DisplayUnit（CDU）.

控制律包括权限,速率,和微调积分,速率限制和其他大部分系统增益一样,在飞行中手动可调,通过RASCAL驾驶员座舱的控制/展示单元.

Toaccuratelyrepresent