Full-Motion Aircraft Simulator Enhancements-Hudspeth

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Skip Hudspeth and Gordon Hayhoe

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Pavement Roughness Subjective

Pilot Rating StudyPhase I - Develop a surface roughness model on the

B737-800 flight simulator for input of real worldairport surface elevation profiles.

Phase II - Develop runway and taxiway pavement

roughness rating scales for determining pavementcondition for maintenance. The rating scales will bebased on pilot's subjective ratings in response tosimulator cockpit motions.

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B737-800 Simulator OverviewSurface Roughness Model EnhancementsChallenges and ResolutionsRoughness Model Testing

Future Work

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FAA B737-800Flight Simulator

Located at the FAAs MikeMonroney Aeronautical Centerin Oklahoma City.

Level D Full Flight Simulator

Six-degree-of-freedom motionsystem.

High resolution visual displayand sound system.

Does not provide real worldsurface roughness models

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Flight Simulator Overview

FlightCompartmentHost

Computer

MotionControlCabinet Motion Platform

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Visual

Display

VisualImageGenerator

Interface


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Computer


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Visual

Display


Interface


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Computer


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Visual

Display


Interface


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Computer


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Visual

Display


Interface


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B737-800 Simulator Motion Platform


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Simulator Motion SystemDue to limited travel, sustained accelerations are notpossible.

Motion system designed to provides accelerationonset cueing.Flight model accelerations are filtered to optimize theavailable motion response for training maneuvers.

An accelerometer mounted below the pilot seatsprovides measurement of cockpit verticalaccelerations.

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Motion System Inputs from the

Flight ModelReceives rigid body accelerations from flight model

Other motion effects are simulated through the useof buffet and special effects generators within themotion system.These include stall and flap buffets, touchdown

bumps, etc.

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Computer


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Visual

Display


Interface


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Flight Model Overview

Equations

of Motion

Thrust Weight Atmosphere

Ground Aerodynamics

SimulatorMotionSystem

SimulatorVisualSystem

Simulator Flight Model

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Existing B737-800 Simulator

Surface Roughness ModelThe simulator provides a generic roughness model

using randomly generated vertical surface deviations.The generic roughness amplitude is selectable withrange from 0 to 5.

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Random vs Actual Surface Roughness

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Generic (random) surface roughness

Regional heavy runway surface roughness


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New Surface Roughness ModelReplaces the random roughness generation withprofiles measured on airport pavements.

Allows selection of surface profiles from simulatorinstructor station.Integrates with existing simulator models. Aligns airport surface profiles with visual scenes.

Provides realistic simulator cockpit motion.

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Surface Profiles Formatted for use

on the SimulatorSurface elevation is uniform across width of the

profile.Elevation units changed from inches to feet.Surface profile sample spacing of four feet.

Profiles were filtered to remove very low frequency variations in elevation.

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Profile Filtering Example

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Runway elevation profile before high-pass filtering

Runway elevation profile after high-pass filtering


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Integration of Surface Roughness

Profiles into the Simulator Flight Model

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SurfaceProfile

StrutModel

GearForces


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SurfaceProfile

StrutModel

FlightModel

Linear /rotationalaccelerations at CG

Flight Model Generates CG Accelerations


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Motion System Transforms CG into Cockpit

Accelerations

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SurfaceProfile

StrutModel

FlightModel

MotionSystem


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Aircraft Flexible Modes

The simulator flight model assumes a rigid aircraftbody.However, aircraft body flexing provides a largecomponent of the cockpit acceleration response tosurface roughness.

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Cockpit vertical accelerations with rigid body modes

Cockpit vertical accelerations with rigid body and four flexible body modes


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Flexible Mode Simulation Assumes lightly damped linearly flexible continuous

body. Four flexible modes were modeled. Implemented on the host computer. Strut force used to excite the flexible modes. Outputs vertical accelerations at the cockpit position. Cockpit vertical accelerations were transformed into

CG pitch accelerations for transfer to the motionsystem.

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Surface Roughness Model EvaluationTests were developed to evaluate the roughness modelperformance through the collection of time historiesof aircraft and surface profile parameters such as:

Landing gear position along profileSurface height at each gear positionGround speed

Landing gear vertical forceC0mputed cockpit vertical acceleration Actual cockpit vertical acceleration

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9/29/2014 27Cockpit vertical acceleration - 130 knots

Cockpit vertical acceleration - 100 knots

Cockpit vertical acceleration - 50 knots

Effect of ground speed on cockpit accelerations


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Cockpit Accelerations: Computed (top) andMeasured (bottom)

Rigid Body Only One Flexible Mode


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Subjective Pilot EvaluationTwo industry pilots were asked to evaluate the realism of variousrunway roughness profiles.The pilots performed the following maneuvers:

TaxiingTakeoffsLandings

The pilots feedback indicated that the profile roughness models

provided a realistic simulation of the real world runways except for theabsence of background tire rumble and cockpit response to centerlinelights and concrete joint bumps.

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Summary A B737-800 simulator surface r0ughness model wassuccessfully implemented allowing use of actualairport surface profiles and providing realistic cockpitmotion response to the profile elevation changes.The surface roughness model provided a distinctenhancement over the existing runway randomroughness models through the use of selectable real world surface profiles.

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Further Work

Phase II of this project is currently in progress with apreliminary test of subjective pilot rating tests plannedfor this summer.

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Contact Information

Gordon F. Hayhoe

FAA Airport Technology R&D Branch, AJP-6312 William J. Hughes Technical Center Atlantic City International Airport, NJ [email protected]

Skip HudspethHudspeth & Associates, Inc.

11130 Johnson Davis RoadHuntersville, NC [email protected]
mailto:[email protected]:[email protected]:[email protected]:[email protected]

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Full-Motion Aircraft Simulator Enhancements-Hudspeth

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