Generalized Automatic and Augmented Manual Flight Control

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航空

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

什么内容的呀？

pongpong

好东西。 谢谢。

renbin

需要这个资料

漫步007

Thx。。。。。。