Auto Pilot Auto-Pilot

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  • Control & Guidance2011

    Enginyeria Tcnica d'Aeronuticaesp. en Aeronavegaci

    Escola d'Enginyeria de TelecomunicaciEscola d Enginyeria de Telecomunicaci i Aeroespacial de Castelldefels

    Adeline de Villardi de MontlaurAdeline de Villardi de MontlaurMarc Diaz Aguil

    Auto PilotAuto PilotAuto-PilotAuto-Pilot

    Control and guidance

    Slide 1

  • 11 L it di lL it di l tt il til t11.. LongitudinalLongitudinal autoauto--pilotpilot

    22 LateralLateral autoauto pilotpilot22.. LateralLateral autoauto--pilotpilot

    33 APAP basicbasic principlesprinciples33.. APAP basicbasic principlesprinciples

    44 FlightFlight ManagementManagement SystemSystem44.. FlightFlight ManagementManagement SystemSystem

    Control and guidance

    Slide 2

  • 11.. LongitudinalLongitudinal autoauto--pilotpilot

    IntroductionIntroduction

    1 Displacement auto1 Displacement auto--pilotpilot

    2 Pitch speed control system2 Pitch speed control systemp yp y

    3 Acceleration control system3 Acceleration control system

    4 Vertical speed control4 Vertical speed control

    5 Mach speed control5 Mach speed control

    6 Altitude control6 Altitude control

    Control and guidance

    Slide 3

  • I t d tiI t d ti

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Note: in all block diagrams, all sum blocks are with a feedback as:

    IntroductionIntroduction

    +

    -

    even if + & - symbols do not appear.

    Control and guidance

    Slide 4

  • I t d tiI t d ti

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Control surface actuator:

    IntroductionIntroduction

    so far, various Transfer Functions (TF) that represent the aircraft dynamics have been seen, still missing some control systems:y , g y

    Servo actuators are used to deflect the aerodynamic control surfaces: either electrical hydraulic pneumatic or some combinationsurfaces: either electrical, hydraulic, pneumatic or some combination of the 3. Typically their TF is of a 1st order system.

    T f f ti f i th t l l ttit d Transfer functions for any sensors in the control loop: attitude gyro, rate gyro, altimeter or velocity sensor: TF for most sensors can been approximated by a gain Kapproximated by a gain K.

    Control and guidance

    Slide 5

  • Di l tDi l t APAP

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    DisplacementDisplacement APAP

    first auto pilot was developed by Sperry Corporation first auto-pilot was developed by Sperry Corporation

    linked a gyroscopic attitude with a magneto-compass to the rudder the elevator and the flaps (with hydraulic system)rudder, the elevator and the flaps (with hydraulic system)

    allowed the plane to flight straight and leveled without pilots attentionattention

    straight-and-level AP is the most common and thus the cheapestcheapest

    low error due to the use of simple control systems

    Control and guidance

    Slide 6

  • Di l tDi l t APAP

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    pitch/attitude angle: between horizontal and longitudinal axis

    DisplacementDisplacement APAP

    Amplifier elevatorservoAircraft

    dynamicsVertical

    Giroscoperef eg ee e p servo dynamicsGiroscope

    plane trimmed to reference pitch turned on AP

    if pitch angle varies, voltage eg is generated amplified servo-elevator (hydraulic for ex.), positions the elevator

    pitch movement so that the aircraft moves with the desired pitch movement so that the aircraft moves with the desired pitch angle

    Control and guidance

    Slide 7

  • Di l tDi l t APAP

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Transfer function represents aircraft dynamics

    DisplacementDisplacement APAP

    Transfer function represents aircraft dynamics

    Remember: 6 hypothesis:

    1. X and Z axis in the plane of symmetry of the aircraft and its gravity center = origin of the system of axisg y g y

    2. Aircraft has a constant mass

    3 Aircraft = rigid solid3. Aircraft rigid solid

    4. Earth = inertial reference frame

    5 Small perturbations with respect to the equilibrium5. Small perturbations with respect to the equilibrium

    6. Leveled, non accelerated, non turbulent flight

    Control and guidance

    Slide 8

  • Di l tDi l t APAP

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    f f

    DisplacementDisplacement APAP

    Longitudinal model transfer function

    Elevators movement:

    0)(74.0)(392.0)()088.078.13( sssus

    )(7100)()19205140()()619005520(

    )(246.0)(78.13)()46.478.13()(48.12

    ssssssu e

    )(710.0)()192.0514.0()()619.00552.0( 2 ssssss e

    Control and guidance

    Slide 9

  • Di l tDi l t APAP

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Short period oscillation modeDisplacementDisplacement APAP

    study of the oscillation

    frequency and damping

    factor after the perturbation

    fast damping without effort

    f th il tfrom the pilot

    Angle of attack in green

    Attitude angle in blueControl and guidance

    Slide 10

    Attitude angle in blue

  • Di l tDi l t APAP

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    S f

    DisplacementDisplacement APAP

    Short period oscillation mode considered for:

    2 examples:

    ti l t t i ft fl i t 150 h t l l conventional transport aircraft flying at 150mph at sea level

    jet flying at 600 ft/sec at 40,000 ft

    Control and guidance

    Slide 11

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    First aircraftFirst aircraft

    )24382()1.3s()s(G 2

    )24.3s8.2s(s)( 2

    Response to a step entry for a non-corrected TF, in open loop

    Control and guidance

    Slide 12

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    )1.3s()s(G

    First aircraftFirst aircraft

    )24.3s8.2s(s)s(G 2

    Aircraft #1 rootlocus (non-corrected)

    Control and guidance

    Slide 13

    ( )

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    First aircraft, basic correctionFirst aircraft, basic correction

    amplifier: proportional controller: K gain amplifier: proportional controller: K gain

    servo-elevator: first order system

    i l ( d)

    1 block

    vertical gyroscope: sum + sensor (not represented)

    Control and guidance

    Slide 14

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Kse=77 5

    First aircraft, First aircraft,

    basic correctionbasic correction Kse 77.5

    )24382()1.3(

    512 2

    sss

    ss

    KG seC )24.38.2(5.12 ssss

    rootlocus, corrected

    Control and guidance

    Slide 15

    ,

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    First aircraft, First aircraft,

    basic correctionbasic correction

    Closed loop response to a step entry,

    for =0 6 K =8 8Control and guidance

    Slide 16

    for 0.6 Kse 8.8

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    )3251s8050s(s)306.0s(39.1)s(G 2

    Second aircraftSecond aircraft

    )325.1s805.0s(s

    Step response for a non-corrected TF, in open loop

    Control and guidance

    Slide 17

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    )3251s8050s(s)306.0s(39.1)s(G 2

    SecondSecond aircraftaircraft

    )325.1s805.0s(s

    root locus (non-corrected)Control and guidance

    Slide 18

    root locus (non corrected)

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Second aircraft, basic correctionSecond aircraft, basic correction

    Control and guidance

    Slide 19

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Kse=38.4Second Plane, Second Plane,

    Basic correctionBasic correction

    )325.1805.0()306.0(39.1

    10)( 2

    sss

    ss

    KsG seC

    corrected rootlocus

    Control and guidance

    Slide 20

  • 1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Second aircraft, Second aircraft,

    Basic correctionBasic correction

    Closed loop response to a step inputClosed loop response to a step input

    with Kse=9 =0.17

    unacceptable response, airplane has very little natural damping and AP is not efficient enough

    Control and guidance

    Slide 21

    natural damping and AP is not efficient enough

  • Di l t APDi l t AP

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Pitch rate feedback

    Displacement APDisplacement AP

    Pitch rate feedback

    Need to increase damping of the short oscillation mode by adding an inner feedback loopg p

    Amplifier servoelevatorAircraft

    dynamicsVertical

    Gyroscoperef eg ee e

    elevator dynamicsGyroscope

    rate gyro

    feedback is added affecting pitch rate feedback is added affecting pitch rate

    Control and guidance

    Slide 22

  • Di l t APDi l t AP

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Displacement APDisplacement AP

    Pitch rate feedbackPitch rate feedback

    for this problem we now have 2 parameters to select,

    using root locus method and trial and error procedure

    Control and guidance

    Slide 23

  • Pitch rate feedback

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Kva=1.82

    Kva=1.21

    Aircraft 2 rootlocus of the inner loopControl and guidance

    Slide 24

    Aircraft 2, rootlocus of the inner loop

  • Pitch rate feedback

    1. Longitudinal auto1. Longitudinal auto--pilotpilot

    Kampcr=138

    Ka