Generalized Automatic and Augmented Manual Flight Control

航空发表于 2010-8-15 21:44:02

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航空发表于 2010-8-15 21:44:47

Generalized Automatic and Augmented Manual Flight Control Anthony A. Lambregts FAA Chief Scientist Flight Guidance and Control Tony.Lambregts@FAA.gov Tel 425-917-6581 Berlin Technical University Colloquium May 19, 2006 Overview • Automatic Flight Controls - State of the Art • automation issues • incident and accidents • requirements • traditional design process • man-machine interfaces • FAA Safety Role • Regulations & Certification; FAR updates - high lights • Generalized MIMO Control • Total Energy Control System (TECS) • Total Heading Control System (THCS) • Condor Application • Fly By Wire Augmented Manual Control State of the Art Flight Guidance & Control throttle δe stick display servo Engine Airplane ΔT sensors clutch clutch servo Autopilot Autothrottle FADEC Actuator Automation Safety Accidents & Incidents • China Airlines B747 spiral dive after engine failure • China Airlines A300 crash at Nagoya, Japan • Air Inter A320 crash near Strasbourg, France • American Airlines B757 crash neat Cali, Columbia • Tarom A310 crash near Bucharest, Rumania • Air France A320 crash near Habsheim France • Britannia Airways B757 speed loss during FLCH • British Airways B747 speed loss during FLCH • Airbus A330 crash near Toulouse, France • Pilot fails to monitor autopilot operation (Mexicana DC10) Autopilot stalls airplane • A/P roll control saturation, engine out (China Airlines B747) • unexpected high altitude automatic disengage, out-of-trim, pilot over controls (MD11) • imperceptible airplane slow roll response, due to A/P sensor failure without proper alert (Evergreen 747) • A/P reaches roll authority limit in icing, / disconnects without timely warning, stall (Embrair Comair, Detroit) • Pilot tries to take manual control, A/P remains engaged, overrides pilot (China Airlines A300, Nagoya) • Pilot overcontrols rudder, after mild Wake Vortex encounter. Vertical Stabilizer fails (AA A300, New York) Accident and Incidents Scenarios Typical Transport Airplane Flight Guidance & Control System as many as 8 LRUs Triple FMS • Mission Planning • Navigation • Performance Autothrottle Yaw Damper Dual Single Dual • Thrust Rating • Thrust Limiting • Flare Retard • highly complex designs • historically evolved subsystems • extensive functional overlap • operational inconsistencies • incomplete envelope protection • SISO control • little or no standardization • Altitude • Heading • V-Path • Speed • H-Path • Vert. Spd Autopilot • Envelope • Autoland Protect. • role and expectations of pilot in automated aircraft • automation - should not induce false sense of security • pilot expects basic operational safety • crew difficulty of keeping abreast of automatic operations • operational complexities: current designs not pilot-like • situation awareness : • mode annunciation /caution and warnings • recognizing / managing abnormal conditions • predictability: when, how, why things happen • mixing manual & automatic can defeat basic safety features • design • SISO control modes: can result in loss of control • poor man-machine interfaces • correct level of automation: keeping pilot “in the loop” • adequacy of initial and recurrent training Automation Safety Issues Operational Complexity • Who is in control? The pilot, FMS, autopilot, autothrottle? • too many overlapping systems, modes , sub modes • what is the system doing, what will it do next? • crew confusion! • inconsistent operations and performance: • different modes, different results: automation surprises! • complex mode logic, e.g. Flight Level Change, VNAV • unsuitable man-machine interfaces, • e.g. attention/ procedure intensive CDU keyboard • inadequate mode annunciation /caution and warnings • when should pilot intervene, or take over • pilots putting too much trust in low integrity single channel designs, not aware their limitations Design Complexity • historic systems evolution has led to • new functions added-ons with each generation • e.g. GLS on 737 NG: 11 LRUs involved! • old problems “solved” by new modes / submodes • e.g. Flight Level Change, VNAV, Thrust modes • automation fragmentation into subsystems • autopilot, autothrottle, FMS, SAS, FBW • each subsystem handled by different organization • design of each function approached as new problem • SISO control : integration difficulties • modes / sub modes cobbled together by intractable mode logic • mix of old and new technologies • digital hardware with analog architectures! • no overall design & integration strategy! Design Requirements “Creep” on a Recent AFCS Program Successive Spec Revisions….. B-777 Avionics Architecture Flight Guidance and Control Design Process • 100 year evolution of systems & subsystems • more capabilities with each generation • most functions “Non-Flight Critical” • only Autoland and manual control considered “Flight Critical” • new technologies/ old control strategies • analog to digital / mechanical to FBW • introduction of Augmented Manual Control • Single Input / Single Output retained • no certified Multi-Variable designs • Major Issues: • outdated Requirements and Design Approaches Single-Axis SISO Control • Single axis SISO automatic control modes have been the standard since earliest days of automation • It works…. most of the time, however…. • stability and performance cannot be guaranteed: • loss of control possible, e.g. vert path modes • full time pilot monitoring required! •SISO control is root-cause of most automation complaints • single controller input not only changes intended variable, but also causes unintended responses of other variables: • need other controller inputs to suppress unintended control coupling errors • poor damping, high control activity • mode proliferation & complexities, operational inconsistencies and pilot confusion BASIC AIRPLANE CHARACTERISTICS: THRUST AND DRAG AS FUNCTION OF SPEED Trust, Drag Speed Trim Drag Speed Power Setting Thrust Point of Neutral Stability Front Side Back Side Stall Speed Stable T P Unstable Trim Point • Generalized all-encompassing MIMO control strategy for all automatic and augmented manual modes • up-front integration of functions • pitch/thrust control • roll/yaw control (including rudder) - inherent • yaw damping /turn coordination • thrust asymmetry compensation • improved failure detection, identification and isolation • envelope protection • airspeed, normal load factor, angle of attack, roll angle FUTURE SYSTEMS REQUIREMENTS • large cost reductions, achievable through • reduced system complexity, less maintenance • faster system development cycle • design reusability- lower risk • reduced customization • standard off-the-shelf hardware • less lab/flight testing • reduction in pilot training need • automation safety improvements FUTURE FG&C SYSTEMS DESIGN OBJECTIVES FG&C • Airspeed/ Mach • Altitude/Vertical Spd • Heading/Track • Loc / GS, V-Nav / L-Nav • Envelope Protection • FBW Manual Mode Tactical Automatic & FBW augmented manual Control Modes and Safety Functions FMC Flight planning • Navigation • Path Definition • Performance Predict. Strategic Airline Operations CDU Oriented Functions T-NAV V-NAV L-NAV P-R-Y MANUAL 340 .712 00 IAS MACH ALT HOLD ALT FPA TRACK HEAD ACQ 0.0 137 135 THRUST MANUAL GA VAR 24500 VARIABLE GS LOC VMAX VMIN • Rational Function Partitioning • No Function Overlap • Common Control Strategy • Simplified Reusable Design Control Targets MCP Future FG&C System Architecture FAA Role • Safety and oversight of Aviation Safety though • Federal Aviation Airworthiness Regulations (FARs) • high level generic design requirements • some specific detailed “Special Conditions” • Aircraft Design Certification & Production oversight • Aircraft Operations and Maintenance oversight • Pilot training/licensing • cooperative safety initiatives with Industry and Research Establishments: • FAA/NASA Aviation Safety Program (ASP) • Commercial Aviation Safety Team (CAST) all have raised awareness of need for better regulations & design : • Updated FAR and AC 25.1329 Updated FAR and AC 25.1329 • Coverage: Autopilot, Autothrust and Flight Director (not FMS) • Key new requirements: • Vertical Modes preferred operational characteristics • engage/disengage/ mode switching transients • warning/alert for autopilot and autothrottle disengage • manual override must not create unsafe condition • significant override force should disconnect autopilot • speed envelope protection (as a minimum crew alert) • logical man-machine interfaces to minimize crew error and confusion • automatic trimming in opposition to pilot input prohibited • prevent “jack knifing” elevator/stabilizer • trim on elevator position, not stick force Generalized Functionally Integrated Multi-Axes Control • Automatic FG&C has contributed in a major way to flight safety • Future FG&C systems can further enhance flight safety, operational effectiveness and reduce system costs through • Generalized Multi-Input / Multi-Output (MIMO) control strategy • pilot-like control, used for all control modes • automatic • augmented manual • envelope protection • reduced mode complexity • fewer Up-Front integrated modes • simpler more intuitive man-machine interfaces • Mode Control Panel (MCP) • advanced displays ( e.g. SVS Terrain, HITS, FPA symbology Generalized Control Concept Targets Feedback Signal Synthesis Airplane Innerloop Force and Moment Control Nav/ Guid Air Data IRU Guidance Error Normalization (Any Mode) Control Commands Coordination Airplane independent design Airplane tailored design • Decoupled Control • Standard Trajectory Dynamics Designed to provide: TECS/THCS Research Project 􀂄 Need for safer/more effectively integrated FG&C system was recognized in late seventies during NASA TCV program 􀂄 Identified Root Cause of most FG&C System Deficiencies 􀂄 Peace meal mode-by-mode systems evolution 􀂄 SIS0 design 􀂄 NASA /Boeing Research Program, initiated in 1979, resulted in 􀂄 Total Energy Control System (TECS) 􀂄 Generalized energy based MIMO Flight Path & Speed Control 􀂄 Detailed system development & extensive Pilot-In-The-Loop simulator evaluations (1980-1985) 􀂄 Validated by Flight Test & In-flight demonstrations (1985) 􀂄 Generalized integrated lateral directional control concept was developed under DARPA/Boeing Condor program (1985-1990), resulting in 􀂄 Total Heading Control System (THCS) Energy based Longitudinal Control Speed Altitude Thrust Control Elevator Control Trim Point • Responses to elevator and throttle are coupled in speed and altitude • Pilots have learned through training to decouple flight path and speed control • Current automatic control modes fail to account for this control coupling: its operation is like giving - throttle to one pilot to control speed - elevator to other pilot to control flight path γ +v􀀅/g γ −v􀀅/g • Elevator and thrust control are ~orthogonal • Throttle controls Total Energy Rate: • Elevator controls Energy Distribution: }This Energy Strategy used to achieve “pilot-like quality” in automatic control Flight Dynamics - Energy Control Relationships Drag g Thrust W v REQ = ( 􀀅 + sinγ ) + • • current autothrottles neglect largest term: Wsinγ • trim thrust in level flight is equal to Drag • • thrust changes produce • elevator produces energy redistribution • conclusion: energy is the right control integration strategy V E g W v t ( 􀀅 + sinγ ) = 􀀅 2 2 1 V g E W h W t = ⋅ + ⋅ ⋅ ( − sinγ ) g W v􀀅 Total Energy Control System (TECS) • concept • thrust controls Total Energy requirement • elevator controls distribution of energy • result: generalized multi-input / multi-output control strategy •speed /flight path mode errors are normalized into energy quantity, fed forward to throttle and elevator: • provides decoupled command responses • consistent/energy efficient operation in all modes • control priority when thrust limits: • generally speed control has priority • exception: glide slope / flare mode • Vmin/Vmax envelope always protected • Vcmd limited to Vmin/Vmax • control authority allocation: handles complex maneuvers Generalized Integrated Automatic and Manual FBW Control MODE CONTROL PANEL FMC IRU CDU THROTTLE ELEVATOR ACTUATOR ENGINE PATH MODES FEEDBACK NORMALIZATION SPEED MODES FEEDBACK NORMALIZATION COMMANDS COORDINATION FEED FORWARD COMMANDS PROCESSING THRUST SCALING PITCH INNER LOOP INTEGRATED FLIGHT GUIDANCE & CONTROL COMPUTER C γ g v􀀅 C COLUMN. EE C ADC TECS Functional Architecture and Mode Hierarchy 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 Altitude Glide Slope Vert. Path IAS Mach Time Nav Flight path Angle Flare Go Around Manual FBW Vmax Vmin V .. Kh Kv 1/g V Rate Limit Rate Limit Generalized Thrust and Elevator Commands Coordination 􀀅v_ c g Tc V δe c Kv 1/g Kv 1/g energy control energy rate control 􀁄 􀁄􀁄 􀁄 γc 􀁄 TECS Core Algorithm Energy Rate Control Engine Control Engine (TLIM). (PATH PRIORTY) Pitch Innerloop Control Actuator KTI S KEI S KTP KEP (TLIM). (SPEED PR) 2-K K + + _ + + _ + _ + + + + +_ + _ Weight Airplane independent design Airplane tailored design T δe γ γc 􀀅v_g Specific Net Thrust Command Pitch Attitude Command (typically) 􀀅 v c _ g (E􀀅 ) Dε SN (E􀀅 ) Tε SN
Control Authority Allocation Example • Maneuver Authority • During climb at Tmax , Vc /g limited to , allowing speed cmd execution by reducing climb gradient temporarily by half • During descent at Tmin , V/g is limited to , allowing speed reduction by temporary level off .5 (— + γ ) . Vg 1.0 (— + γ ) . Vg = (— + γ ) . Vg .
Envelope Protection Functions • Airspeed: keep between Vmin and Vmax, preferably at IAScmd • Solution can get very complex in traditional systems • requires mode switching & crew alerting • Normal Load Factor (nz): • automatic modes: |nz| < .1 for passenger comfort • FBW manual mode: • 0 < nz < (nz)structural limit • low speed: nz < (nz) α-limit ; (nz) α-limit = (Ve/Vestall-1g)2 • Angle of Attack (α) limit: implicit if nz and Airspeed protected • Bank Angle: bank limit depends on mode & flight condition • Sideslip (β) limiting: possible in some FBW manual designs
TECS/THCS Mode Control Panel Concept with Integrated ATC data link Functions Advanced Displays TECS Digital FCC / Throttle /FADEC Interface Concept Weight FCC Engine T FADEC Engine T FADEC IO Engine failure logic Tcmd throttles s s A to D servo No of oper engines Total Heading Lateral-Directional Control Strategy Design approach analogous to TECS: • aileron control sum of heading and sideslip errors • rudder controls difference between heading and sideslip errors Resulting Total Heading Control System (THCS) algorithm provides • full-time coordinated innerloop roll/yaw control (THCS Core) • yaw damping • turn coordination • engine-out thrust asymmetry compensation / δr & δa trim • envelope protection (bank angle & sideslip) • all outerloop modes • automatic modes (Heading/Track angle, LOC, LNAV) • augmented manual mode • decrab / flat turn capability • consistent performance - all modes / all flight conditions THCS Functional Architecture and Mode Hierarchy Roll Attitude Command Generalized Roll Attitude and Yaw Rate Commands Coordination + + +_ +_ +_ +_ +_ 􀁄 􀁄 􀁄 Drift Angle Corr Heading Command 􀁄 􀁄 􀁄 􀁄 􀁄 􀁄 L-Nav Loc Kψ Sideslip Kβ Command ψ β 􀁄 􀁄 􀁄 􀁄 Ky V Yaw Rate Command ψ c β c Track Angle Command ψ . β . .. Cross Track Deviation Cross Track Velocity Cmd Track Angle Command THCS Core Algorithm + _+ _ + _ + _ + _ + + Kψ Kβ f(q )c g VTrue g VTrue VTrue g KRI S KYI S Kφ Kψ􀀅 K p + _ φ p ψ􀀅 ψ􀀅 + _ ψ ψc + _ β β c Airplane independent design Airplane tailored design f(q )c Actuator Actuator δa δr φc 􀀅ψc 􀀅 βc il 􀀅 β 􀁄 􀁄 􀁄 􀁄 -1 -1 ψ􀀅col TECS and THCS Application on Condor
 
 
 
 
 
 
 
The Condor Team Fly-By-Wire Design • Definition: Airplane control concept whereby surfaces commanded through electrical wires • Sought benefits: – Weight reduction – elimonation of mechanical systems – Drag reduction - Optimized aerodynamic performance by Relaxed Static Stability – Standardized / improved handling qualities through SAS and CAS – Cost reductions • Improved fuel economy • Reduced pilot training (common type rating) • Design commonality/design cycle time reduction • Reduced maintenance FBW Functional Architecture throttle actuator engine δe Airplane ΔT FLIGHT CONTROL COMPUTER display Inter face trim up down actuator δS stick feel system FBW Design Opportunities • simplify operations concept • simplify hardware architecture and design • shedding historically accumulated “baggage”, e.g. design features typically belonging to previous generations of technologies: • complex feel systems • column, wheel back-drive systems • stick shaker, stick pusher • individual actuator loop closure - Force Fight • Instead of designing Band-Aids to make it possible for the pilot to live with the vagaries in the system, the FBW system should eliminate these vagaries (and Band-Aids) Major FBW Design Issues • Controllers - Column & Wheel versus Sidestick • Feel system - Passive (e.g. spring) or Active (expensive !) • Control augmentation - Algorithm response type • simple or none - little or no HQ advantages • stability/command – substantial benefits possible • more complex/costly – many issues • Handling Qualities: what HQ, how best achieved • envelope protection - major safety benefit ! • Good design enhances pilot control authority • mode changes takeoff/landing • Actuators: loop closure, e.g. central or remote loop closure • Redundancy architecture & component reliability Handling Qualities Definition: The conglomerate of characteristics and features that facilitate the execution of a specific flight control task; includes display and feel characteristics • good HQ requires design attributes appropriate to control task (e.g. pitch attitude, FPA, or altitude control) • each task has a finite time allotment or expectation for its completion (bandwidth requirement) • direct control of “slow variables” requires special design attributes (e.g.FPA response augmentation & display) • control harmony is achieved when the pilot can execute the task without undue stress and conscious effort FBW Control Response Attributes for Good HQ Desired Attributes: • “K/S”- like response • low response lag τ • correct sensitivity K • good damping • no overshoot • control harmony with other variables (θ, γ, nz) • consistency between flight conditions Time Response Theta, FPA Input δcol Sensitivity (slope) Lag τ KS NOTE: signal δcol can serve as the cmd reference KS FBW Control Algorithm Types • Pitch: • pitch attitude rate command (+ pitch attitude hold) • nz-command • proportional angle of attack (AOA) command • C*= nz command / Vertical Speed hold • FPA rate command / FPA hold • Roll: roll rate command / roll attitude hold + heading or track hold for bank angle < Xo • Yaw: sideslip command proportional to pedal Given sufficient know-how, all of these concepts can be made to perform well : the devil is in the details! Basic FBW System Example Embraer RJ-170 / DO-728 concept stick δe Air Data Actuator Actuator Electronics Pos sensor Modular Avionics Units Passive Feel Default Gains IRU Airspeed Gain Sched AOA limiting default Autopilot servo clutch Autopilot cmds Raytheon Low Cost GA FBW Concept Bonanza Flight Demo System throttle servo engine δ e Airpl FCC ΔT display stick Decoupled Control Algorithm sensor sensor clutch clutch servo Vcmd FPAcmd • Stick commands proportional FPA; Throttle commands speed Trim Down Up Rationale For Low End GA FBW • Eliminate most low pilot skill related accidents • stall, spin • Loss of Control due to spatial disorientation • Lack of IMC flight skills (inadvertent weather) • Accept new FBW system related accidents, but lower overall rate Approach: • embedded envelope protection functions • low cost FBW design strategy: • simple control algorithm • simple high reliability components • dual sensor set, computer and data bus • basic redundancy and FDIR strategies, e.g. • single servo on split surfaces C* Design Concept KS KI S act. engine Vc o g throttle +_ nz pilot q ++ stick FF shaping δe ΔT Airplane ACE FCC comp C* C*cmd C* Morphed into FPA rate cmd/hold • responses identical to original C*, if gains are equivalent • fewer, simpler sensors • no pilot-out-of-the-loop control reference drift • still need extensive flight condition tuning • missing: integral control of γ-error actu engine throttle q δ e ΔT Airplane Kq KFF Kθ stick θ γ cmd γ K γ + Prefilter KI S _ +_ ++_ Augmented Manual Control Algorithm Design Objectives • produce a generalized reusable design with • generic innerloop, shared with automatic modes • integral feedback control, to prevent response droop • final dynamics = classical airplane with ideal constant speed HQ: • no undesirable response variability with flight condition • responses decoupled from airspeed - by autothrust • tracking of Control Reference when pilot out of the loop, e.g. • pitch/roll attitude • flight path angle (preferred – minimizes workload) {(1/ω )S (2 / ω )S 1}(τ S 1) (τ S 1)(τ S 1) S K {(1/ω )S (2ζ /ω )S 1} (τ S 1) S K δ θ SP SP d 2 2 SP stick n1 n2 SP SP 2 2 SP stick n stick + + + + + = + + + = ζ {(1/K K K )S (1/K K )S (1/K )S 1}(τ S 1) (K S K S 1) S K δ γ I θ2 2 θ I 3 q θ I FFI 2 stick FFP stick + + + + + + = Proposed Design Methodology for FBW Control Algorithms Desired: • systematic/reliable process, producing desired results: • generalized/reusable design – minimal application & Flt Condition adaptation Approach: Step 1: Stability Augmentation using Static Inversion 􀂃 eliminates flight condition dependencies, gain schedules 􀂃 defines basic SP innerloop characteristics: ω, ζ Step 2: Add Integral Feedback loop 􀂃 “retrims” airplane - eliminates SS command response droop Step 3: Add Command Augmentation Feed Forward Paths 􀂃 shapes response to pilot control inputs, as desired 􀂃 provides “Hold” function for pilot established command TECS FPA Control Algorithm Implementation stick δe Airplane Invariant Short Period design 1 1 2 θ S + τ FPA γ KStick S 1 γc γc . Pitch rate Pitch attitude Feed Forward Control Augmentation Static θ Inversion FPA Feedback Control Augment. Short Period Dyn. γ Pilot Induced Oscillation Avoidance • pilot in the loop control requirements • bandwidth - appropriate to the task • response predictability • linearity highly desirable • suitable controller forces & displacements • display(s) – appropriate to pilot task • overall system design harmony - need • adequate control algorithm bandwidth • adequate actuator bandwidth and rate limits • correct controller sensitivity & authority • matching of front-end and back-end design • display dynamics appropriate for pilot loop closure Questions??

f214216709 发表于 2010-9-6 16:20:23

什么内容的呀？

pongpong 发表于 2010-9-8 13:10:15

好东西。谢谢。

renbin 发表于 2010-10-31 09:16:37

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需要这个资料

漫步007 发表于 2010-12-29 16:25:52

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Thx。。。。。。

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Generalized Automatic and Augmented Manual Flight Control

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