Flight Control Law Design: An Industry Perspective - PowerPoint PPT Presentation

About This Presentation
Title:

Flight Control Law Design: An Industry Perspective

Description:

In 2002 alone, 490 flight control design related papers were published. ... Lateral tracking uses classical PI control with tuning parameters ... – PowerPoint PPT presentation

Number of Views:2942
Avg rating:3.0/5.0
Slides: 72
Provided by: tamaske
Learn more at: https://dept.aem.umn.edu
Category:

less

Transcript and Presenter's Notes

Title: Flight Control Law Design: An Industry Perspective


1
Flight Control Law DesignAn Industry Perspective
2003 European Control Conference
  • Gary J. Balas
  • balas_at_aem.umn.edu
  • Aerospace Engineering and Mechanics
  • University of Minnesota
  • Minneapolis, MN 55105 USA
  • September 4, 2003

2
Presentation Overview
  • Survey of the control techniques being used by
    industry in Brazil, Europe, Russia and the United
    States of America to design flight control laws
    for fixed-wing aircraft.

3
Outline
  • 100 years of Controlled Flight
  • Introduction
  • Background
  • Countries
  • Brazil
  • Europe
  • France
  • Germany
  • Italy
  • Sweden
  • United Kingdom
  • Israel
  • Russia
  • United States of America
  • Boeing
  • Honeywell
  • Lockheed Martin
  • Summary

4
Wright Brothers December 17, 1903
  • First to develop a fully aerodynamic control
    system coupled to a powered aeroplane which was
    both flyable and maneuverable.

5
United Kingdom
  • Most Influential Predecessor of the Wrights
  • Sir George Cayley in 1799 at Brompton, near
    Scarborough in Yorkshire sketched a
    conventional configuration of an aeroplane.
  • Indeed, in 1909 Wilbur Wright himself paid Cayley
    the following tribute
  • "About 100 years ago, an Englishman, Sir
    George Cayley, carried the science of flight to a
    point which it had never reached before and which
    it scarcely reached again during the last
    century.
  • The History of Flight from Around the World,
    United Kingdom, Eur. Ing. Dr. J.A.D. Ackroyd

6
Cambridge University, England
  • Lord Kelvin, President, Royal Society,
    undergraduate at Cambridge University, Senior
    Wrangler

7
Cambridge University, England
  • Lord Kelvin, President, Royal Society,
    undergraduate at Cambridge University, Senior
    Wrangler

Heavier-than-air flying machines are impossible
(1895) "I have not the smallest molecule of
faith in aerial navigation other than
ballooning...I would not care to be a member of
the Aeronautical Society," (1896)
8
Current/New Commercial Aircraft
9
Current/New Military Aircraft
Saab Gripen
10
Current/New Military Aircraft
Sukhoi SU-37
F/A-18 E/F
11
Uninhabited Aerial Vehicles (UAVs)
12
Uninhabited Aerial Vehicles (UAVs)
Dragon Drone
Pioneer
FPASS
13
Uninhabited Aerial Vehicles (UAVs)
  • US Department of Defense (DoD) has 20 UAVs in
    service or under conceptual development
  • DoD will have invested over 10 Billion in UAVs
    by 2007.
  • DoD UAV systems will grow to 300 by the year
    2010.
  • 32 Nations are developing more than 250 models of
    UAVs.
  • Over 60 small and Micro UAV programs are under
    way through out the world.
  • DoD Unmanned Aerial Vehicle Roadmap 2002-2027

14
Background
  • Flight control design research is a very active
    area
  • In 2002 alone, 490 flight control design related
    papers were published.
  • Majority new theory or applying theory to
    aircraft simulations.
  • Basis from which the aircraft industry draws its
    new ideas.
  • Working Group 23 of Advisory Group for Aerospace
    Research and development (AGARD now RTO) noted in
    1996
  • Skill required to design an advanced flight
    control system is not easily transferred and very
    little material exists in the open literature to
    be used as a reference handbook by designers.
  • RTO recommended better documentation of existing
    flight control system development process,
    lessons learned and best practices.

15
Background
  • Survey of the current practices and control
    design approaches used by the aircraft industry.
  • Brazil , Europe (France, Germany, Italy, Sweden,
    United Kingdom), Israel, Russia, United States
    of America
  • Caveats
  • Limited information on techniques used in
    industry.
  • Some companies consider the control architecture,
    algorithms etc. to be IP.
  • Companies that publish more are better
    represented in this talk.
  • Almost all the references cited were published in
    English.

16
Brazil
  • Embraer ERJ-170 aircraft
  • Flight control design philosophy
  • Docile and benign as possible flying qualities
    behavior (behaviour)
  • Digital fly-by-wire (FBW) control system would
    allow complex flight controllers, cost
    constraints and accelerated time schedule led to
    selection of standard classical flight control
    system.
  • In-flight simulation using Veridian Variable
    Stability Learjet.

17
Europe
18
Europe
  • Long tradition of aeronautical research.
  • Close links between universities and industry
  • To increase cooperation, the Association of
    European Research Establishments in Aeronautics
    (EREA) found in 1994.
  • CIRA (Italy), DERA (Great Britain), DLR
    (Germany), FFA (Sweden), INTA (Spain), NLR
    (Dutch) and ONERA (France, 1999).
  • Group for Aeronautical Research and Technology in
    Europe (GARTEUR)
  • GARTEUR Flight Mechanics Action Group 08
    (1994-1997)
  • Robust control design methods
  • GARTEUR Flight Mechanics Action Group 11
    (1999-2002)
  • New Analysis Techniques for Clearance of Flight
    Control Laws
  • Many European aircraft industries are
    multi-national and parts of the same aircraft
    flight control laws are designed in more than one
    country.

19
France
Concorde
20
France
  • Mirage 2000, Rafale C
  • Airbus
  • Major partner in European consortium of French,
    German, Spain and U.K. companies
  • A300/A310, A320, A330/A340, A380 under design.
  • Developer of commercial fly-by-wire (FBW) system.
  • A320 was first commercial aircraft to enter
    service with a FBW flight control system (1988).
  • A340 2nd generation FBW certified in 1992.
  • All Airbus flight control surfaces are
    electronically controlled and hydraulically
    activated.
  • UAVs

21
France Airbus A320
  • A320 Flight Control Laws
  • Improve the natural flying qualities,
    particularly the stability, control and flight
    envelope protection.
  • Longitudinal Control
  • Load factor demands
  • Classical proportional plus integral control
  • Lateral-directional Control
  • Roll rate, sideslip and bank angle commands
  • Classical proportional plus integral control with
    a gain matrix for stability and roll
    rate/sideslip decoupling.

22
France Airbus A340
  • A340 Flight Control Laws
  • Reproduced architecture/principles for A320
  • Increased size and flexibility, required addition
    of structural mode control to reduce structural
    mode vibration.
  • Structural Mode Suppression Controller
  • Manual flight controller/Autopilot modified to
    eliminate interaction.
  • Turbulence damping function added to attenuate
    fuselage response.
  • Sufficient bandwidth separation between two
    controllers minimized interaction.
  • Accelerometers were added to sense vibration.

23
France Airbus A380
  • A380 Flight Control Laws
  • High capacity, long range
  • Flexibility increases interaction between control
    laws and structural dynamic modes.
  • Aeroservo-elastic coupling traditionally solved
    by filtering/decoupling, would require reducing
    control bandwidth.

24
France Airbus A380
  • Airbus A380 Approach
  • Airframe flexibility taken directly into account
    when designing the flight control laws.
  • Integrated flight control laws to achieve desired
    handling qualities and flexible mode damping
    requirements leading to extended control
    bandwidth.
  • Flight tested on A340 using A380 models
  • Robust to fuel, payload, etc. variations
  • Same concept applied to autopilot and manual
    control laws.

25
Germany
  • Commercial Aviation
  • Airbus
  • DLR experimental aircraft (ATTAS) Advanced
    Technologies Testing Aircraft System.
  • Military Aviation
  • Eurofighter
  • X-31 (US/Germany program)

26
Germany
  • X-31A Post stall experimental aircraft
    (US/Germany program)
  • First X program with Intl partner
  • Enhanced Fighter Maneuverability
  • EFM using thrust vectoring
  • Goal tactical advantage of EFM in post stall up
    to 70 deg AoA
  • Rockwell and MBB
  • X-31A Flight Control Laws
  • Pilot cmd (p,q,r)
  • Sensed feedback (p,q,r,?,?)
  • Actuation cmd (?SF ,?DF, ?C, ?R,?,?)
  • K - LTI controller
  • Optimal LQ digital regulator
  • Scheduled with ?, M, h
  • Nonlinear feedforward blocks

27
Germany
  • VECTOR X-31A program
  • Vectoring Extremely short-takeoff-and-landing
    Control Tailless Operation Research (VECTOR)
  • Boeing, US Navy, German BWB and EADS

28
Germany
  • Flight control system for A380
  • Size and flexibility
  • EU funded REAL (Robust and Efficient Autoland
    control Law design).
  • Industry and research institutions from France,
    Germany and the Netherlands
  • Benchmark was DLR ATTAS aircraft.
  • DLR REAL flight control design approach
  • Multi-Objective Parameter Synthesis (MOPS).
  • Robustness addressed via multi-model,
    optimization, Monte-Carlo analysis.

29
Germany - REAL
  • Stability/command augmentation, tracking,
    guidance
  • Inner loops designed using dynamic inversion.
  • Total Energy Control System (TECS)
  • Lateral tracking uses classical PI control with
    tuning parameters
  • Tuning based on multi-criteria/multi-model
    parameter opt using MOPS.

30
Germany - REAL
  • DLR autoland controller flight tested in 2000
  • DLR autoland control performed well.
  • Nonlinear ATTAS simulations
  • Technical University of Deflt (Netherlands)
    developed a ?-controller to replace the dynamic
    inversion inner-loop controller.
  • ONERA (France) developed a fixed-order H?
    controller.

31
Germany - IRIS-T
  • Infra-Red Imagining System-Tail (IRIS-T) Missile
  • Thrust-vectored control, next generation
    short-range missile.
  • Being developed with Greece, Italy, Norway and
    Sweden.
  • Extreme maneuverability.
  • ?-synthesis robust control technique used to
    design lateral and roll controllers.
  • Scheduled on dynamic pressure
  • Successful flight test in May 2000.

32
Italy
  • Eurofighter
  • Germany, United Kingdom, Italy, Spain.
  • Quad redudant, full authority DFCS.
  • Alenia responsible for basic autopilot
  • Longitudinal axis controls attitude or pitch
    angle, lateral axis controls bank angle and
    heading.
  • Autopilot designed using classical control tools.
  • Control structure defined, Nicholas/Bode plots,
    linear time responses.
  • Large amplitude, nonlinear closed-loop
    simulations.
  • Modified control structure with nonlinear
    elements.
  • Mode logic increased nonlinear elements to
    satisfy mode schedules.

33
Sweden
  • Saab/BAE JAS 39 Gripen
  • Contract awarded in 1982
  • Lightweight, multi-role combat aircraft
  • All moving, delta canard configuration
  • Hungary (2003) orders 14, 232 ordered

34
Sweden
  • Pilot-induced Oscillation (PIO)
  • First test aircraft crashed after 6th flight
    (1989), first operational aircraft crashed in
    1993.
  • Partial cause PIO related to control surface
    servo rate limits.
  • Reduced phase margin or extra delay in feedback
    loop.

35
Sweden
  • Controller modification based on PIOs
  • Feedback phase compensation based on anti-windup
    methods.
  • Increased or advanced phase around nonlinearity.
  • Low pass filters used to eliminate biases and
    high frequency roll off issues
  • Flight tested and verified.
  • Phase compensation technique used in place of
    rate limiters in Gripen production flight control
    system.

36
United Kingdom
  • Commercial
  • Airbus
  • Military
  • Harrier
  • Saab/BAE JAS 39 Gripen
  • Eurofighter
  • Lockheed Martin/BAE F-35 JSF

37
UK - Jaguar and EAP Programs
  • FBW Jaguar program (1980s) precursor to VAAC
  • Prove principles of active control technology,
    establish design and flight clearance techniques
    for DFCS.
  • First UK aeroplane equipped with full authority
    DFCS.

38
UK - Jaguar and EAP Programs
  • Experimental Aircraft Programme (EAP, 1983-1995)
  • Follow on from Jaguar programme.
  • Control design process
  • Linear low frequency PI scheduled as function
    control
  • Nonlinear trim distribution, nonlinear control
    power, nonlinear variations of stability
  • Linear high frequency avoid structural coupling
  • Lessons learned separate regulator and command
    path designs.
  • FBW Jaguar and EAP shaped Eurofighter flight
    controller

39
United Kingdom
  • Vectored thrust Aircraft Advanced Control (VAAC)
    program
  • Inception in 1984.
  • Handling, control and display requirements for
    future short takeoff/vertical landing (STOVL)
    aircraft.
  • Experimental FBW VAAC Harrier.
  • Development and testing of advanced aircraft
    flight control algorithms.
  • Longitudinal axis, integrated management of
    thrust vectoring and aerodynamic forces for
    decoupled control.

40
UK - VAAC Control Strategies
  • Classical control, loop-at-a-time
  • Frequency shaping, gain-scheduling, significant
    nonlinearities linearized with inverse functions,
    iterative design.
  • Anti-windup scheme and control allocation.
  • Nonlinear static inverse
  • Nonlinear inverse of the aircraft to determine
    control effectors to trim. aircraft at a given
    maneuvering state.
  • Constrainted design process used to define unique
    solution to non-linear inverse problem (trim
    map).
  • Nonlinear inverse feed-forward combined with low
    gain, classical feedback design for stability.

41
UK - VAAC Control Strategies
  • Nonlinear Dynamic Inversion (NDI)
  • Nonlinear dynamic model of aircraft used to
    invert nonlinearities and a classical PI
    controller designed to track desired pitch rate
    command.
  • Pilot commands filtered prior to input to NDI
    controller.

42
UK - VAAC Control Strategies
  • H? loop shaping
  • Multivariable linear controllers at 4 points
    hover-to-forward flight.
  • Inner-loop pitch rate feedback used to reduce
    effect of pitch moment due to thrust changes.
  • Outer-loop 3-input/3-output, H? loop shaping to
    control normal and forward acceleration and
    incidence.
  • Weight selection similar to classical
    loop-shaping.
  • Four linear point designs gain-scheduled
    throughout flight envelope.
  • Controller implemented in observer form.
  • Interpolated controller gains and interpolated
    controller outputs.
  • H? loop shaping techniques also used to
    synthesize an integrated longitudinal/lateral
    flight and propulsions control system for VAAC.

43
UK - VAAC Control Strategies
  • Linear, parameter-varying (LPV) controller
  • System dynamics written as LTI models whose
    state-space coefficients are a function of
    scheduling variable(s).
  • LPV H? loop shaping uses LPV model of nonlinear
    aircraft dynamics to directly synthesize a
    scheduled LPV controller.
  • Successfully implemented at tested between 1995
    and 1998.

44
Israel
  • Light, multi-mission fighter Lavi
  • Initial flight test 31 Dec 86, program
    terminated 30 Aug 87
  • Flight control laws
  • Classical technique with optimal control methods
    used in preliminary design process.
  • Lessons learned Relationship between control
    design parameters and flying qualities.
  • UAVs

45
Russia
46
Russia
47
Russia
48
Russia
  • Extensive history of military/commercial aircraft
    development.
  • English language literature on Russian industry
    flight control design techniques is limited.
  • Sukhoi 37 FBW flight controller
  • Quad redundant DFCS
  • Design requirements
  • Good handling qualities.
  • Optimal trimming.
  • Reconfigurable under flight control system
    failures to maximize control moments and trim
    configuration.
  • Adaptive controller designed to eliminate small
    amplitude self-induced oscillations due to
    actuator nonlinearities.

49
Russia - SU-37 Aircraft
  • Canards and thrust vectoring (TV loop not
    shown.).
  • Longitudinal controller synthesized with
    classical control methods.

50
United States of America (USA)
  • Commerical
  • Boeing (McDonnell Douglas)
  • B-717, B-737, B-747, B-757, B-767, B-777
  • Honeywell
  • Military
  • Lockheed Martin (General Dynamics)
  • F-16, F-22, F-35 (JSF)
  • Northrup Grumann
  • F-14, F-20, B-2
  • Boeing (McDonnell Douglas, North American
    Rockwell)
  • B-52, B-1B, C-17 C-40A, F/A-18, KC-10
  • Honeywell

51
USA
B-747
52
USA
B-747
53
USA - 1947
B-747
54
USA Flight Control Specifications
  • Multivariable Control
  • Multiple sensors, disturbances, objectives,
    surfaces (TV) with coupling.
  • Military specifications focus on SISO,
    loop-at-a-time analysis
  • Multivariable Control Design Guidelines (1996)
  • Honeywell Research Labs, Lockheed Ft. Worth,
    Lockheed Skunk Works
  • Eigenstructure assignment, dynamic inversion,
    ?-synthesis
  • F-177, YF-22 and MCT/F-16
  • Report provides a reference point for the US Air
    Force to evaluate the design of future flight
    control systems.

55
Boeing
  • The Boeing Company
  • Largest manufacturer of aircraft in the world.
  • Merger of Boeing, Rockwell International and
    McDonnell Douglas
  • Variety of approaches to flight control design
  • Multivariable Flight Control
  • First application in 1978 as part of a NASA
    research program.
  • Since 1980s, multivariable control as been
    applied to a number of aircraft
  • Multivariable control with classical
    frequency-domain interpretations.
  • Guidelines to transform design requirements into
    math
  • Training of control engineers
  • User-friendly control software programs.

56
Boeing
  • Multivariable Control Design
  • LQR/LQG based
  • Performance and robustness
  • Direct tradeoff between command response, control
    activity, disturbance rejection and loop
    bandwidth
  • Key Selection of variables to regulate and
    controls to perform regulation
  • Integral regulators augmented, zero
    steady-state errors to constant inputs

57
Boeing
  • Integral LQR/LQG design procedure
  • Select controls and regulated outputs controls
    regulated variables.
  • Check singular values and transmission zeros.
  • Attach integrators and set target zeros.
  • Select Q and R matrices for LQR problem.
  • Q and R selected based on command loop crossover
    frequencies.
  • Q ( R ) diagonal, qi (ri) adjusts bandwidth of
    command loop for yi (ui).
  • Check loop at input to integrator and actuator.
  • Note that the control loop crossover frequency is
    limited by the actuator capabilities and
    structural mode coupling.
  • Verify that the phase margins at higher
    frequencies are sufficient.
  • Feed-forward gains adjusted for flying qualities.

58
Boeing
  • Applied to B-767, JSF (Boeing), UCAV, JDAM MMT
    and ACTIVE F-15.

59
Boeing X-36
  • X-36 Prototype fighter aircraft
  • Stealth and agility prior to UCAV
  • 28 scale, remotely piloted
  • Reconfigurable flight control laws
  • Reconfigurable flight control laws
  • Dynamic inversion (DI)
  • Explicit model following framework
  • On-line neural network (NN) to adaptively
    regulate inversion error
  • Uncertainties
  • Failures
  • Damage
  • Desired dynamics and control mixer same for DI
    and adaptive NN

B-747
60
Boeing X-36
  • Reconfigurable flight control laws
  • NN able to stabilize vehicle following failures
    and damage.
  • On-line NN adaptively canceled inversion error.
  • NN/DI controller provide improved HQ when
    failures occurred.

B-747
61
Honeywell
  • Honeywell Research Center (Honeywell Labs)
  • Significant contribution to areas of robust
    control and dynamic inversion.
  • Approach to NDI is MACH (Multi-Application
    Control).
  • MACH is a modular, nonlinear multivariable design
    approach.
  • Blends classical control design with inversion.
  • Outer-loop controllers Proportional or PI.
  • Inner-loop controllers Dynamic Inversion .

62
Honeywell MACH
  • Outer loops multivariable signal shaping
    provides position command and rate tracking.
  • Inner loops NDI to normalize vehicle dynamics to
    be integrators.
  • NDI requires on-board model (OBAC).
  • Estimate derivatives of aircraft states and
    control variables (CV).

B-747
63
Honeywell MACH
  • Five components of MACH
  • 1. Select controlled variables (CV) for
    performance/robustness.
  • 2. Outer-loops convert pilot/guidance commands
    into CV commands.
  • Nonlinear elements such as limiters.
  • 3. Desired dynamics define dynamic behaviour the
    CVs should follow while tracking their commands.
  • 4. NDI attempts to solve the equations of motion
    for actuator commands to satisfy CV desired rate
    of change.
  • Control allocation logic may be necessary.
  • 5. OBAC computes nonlinear vehicle dynamics for
    inversion.
  • Least-squares used to approximate aerodynamic
    data.

B-747
64
Honeywell MACH
  • Initial controller for Lockheed Martin JSF
    vehicle (1995-97).
  • Successfully flight tested on X-38 V132.

B-747
65
Lockheed Martin
  • Leading producer of military aircraft
  • F/A-22 Raptor
  • Air superiority.
  • Stealth and agility.
  • Sustained supersonic cruise.
  • YF-22 (initial demonstrator) flight control
    designed using eigenstructure assignment.
  • Series of pitch oscillations 13m above ground
    lead to aircraft impacted on runway (1992).
  • PIO due to control surface rate/position
    saturation, time delays.
  • JSF F-35

66
Lockheed Martin - F/A-22
  • JSF F-35
  • F/A-22 flight control law redesign
  • Excellent flying qualities and lessons learned.
  • Classical control combined with eigenstructure
    assignment.
  • Removal of pitch integrator key to redesign.
  • Addition of first order pitch stick command
    pre-filter needed to recover flying qualities
    requirements.
  • Classical tradeoff between pitch attitude and
    flight path angle bandwidth.
  • Redesigned flight control law successfully
    achieved Level I handling qualities for all
    closed-loop tracking tasks.

67
Lockheed Martin - JSF
  • JSF F-35
  • F-35 Joint Strike Fighter (JSF).
  • Conventional takeoff/landing (CTOL/AF).
  • Aircraft carrier landing (CV/Navy).
  • Short-takeoff/vertical landing (STOVL/Marines).
  • All variants will fly same set of flight control
    laws.
  • JSF Flight control law design
  • Direct mapping of flying qualities to control
    laws.
  • Nonlinear dynamic inversion control design.

68
JSF Flight Control Laws
  • Controller structure decouples flying qualities
    from a/c dynamics.
  • Regulator/Commands implement desired.
  • Effector blender optimally allocates desired
    acceleration commands.
  • On-board model.
  • Control effectiveness matrix.
  • Estimated acceleration for dynamic inversion.

B-747
69
JSF- Mission X
70
Summary
  • Use of multivariable control techniques to
    design the flight control laws for new aircraft
    is standard.
  • Dynamic inversion is the most widely applied
    multivariable control design technique in the
    aircraft industry.
  • Dramatic change from 15 years ago when almost all
    flight control laws for aircraft were designed
    using classical control techniques.

71
Acknowledgments
  • Rick Hyde Martin Hanel
  • Kevin Wise Ralph Paul
  • Dale Enns Dominique Briére
  • Chris Fielding Frank Thielecke
  • Dagfin Gangass Greg Walker
  • George Papageorgiou Prof. Alexander Efremov
  • Krister Fersan David Bodden
  • Prof. Fred Culick
  • This work was funded in part by the NASA Langley
    Cooperative Agreement NCC-1-337, Dr. Celeste
    Belcastro Program Manager, Dr. Christine
    Belcastro, Technical Monitor.

Write a Comment
User Comments (0)
About PowerShow.com