Hardware-In-the-Loop Simulation of an Aircraft Brake System

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Alan Johnson, Andrew N. Hall, Gary McKay. System Design and Integration. Cessna Aircraft Company. Page 2. 2. Outline. • Antiskid Background. • Motivation.
Hardware-In-the-Loop Simulation of an Aircraft Brake System Alan Johnson, Andrew N. Hall, Gary McKay System Design and Integration Cessna Aircraft Company

MathWorks Aerospace & Defense Conference 2006 1

Outline • Antiskid Background • Motivation • HIL: Hardware; Software • Antiskid Control • HIL Tests • Concluding Remarks

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Cessna makes jets, too. 3

Why antiskid? • Better performance • Even tire wear • Directional stability • Safety

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pedals accumulator

reservoir

pump

antiskid valve

brake metering valve antiskid control box

Antiskid Brake System

brake

wheel speed transducer

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Experimental Flight Data

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Motivation:

• Product improvement • Smooth ride • Engineering curiosity

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• Flight test – expensive • Analytical – slow simulation • Hybrid – HIL: real-time; cost?

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HIL Simulation • Already had: – MATLAB – Simulink – Real-Time Workshop

• PIII leftovers • Compatible A/D – D/A card • xPC Target

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HIL: Hydraulic components 10

HIL: Computer interface 11

Simulink airplane

pedals antiskid valve

accumulator

brake reservoir

pump

brake metering valve VCO

Simulink airplane

antiskid control box

HIL Block Diagram 12

aero

3 DoF

brake and landing gear

FD = μFz

Simulink airplane model 13

tire-road force

D/A A/D wheel-tire inertia

brake torque

slip velocity

Wheel-tire equation of motion:

τ

= Iα 14

NASA TN D-1376, Figure 78 1

0.8

mu

0.6

0.4

0.2

0 0

0.2

0.4

0.6

0.8

1

slip ratio

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NASA TN D-1376, Figure 78 1

0.8

mu

0.6

50 knots 0.4

0.2

0 0

0.2

0.4

0.6

0.8

1

slip ratio

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NASA TN D-1376, Figure 78 1

0.8

mu

0.6

50 knots 0.4

0.2

0 0

0.2

0.4

0.6

0.8

1

slip ratio

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Some Assumptions and Limitations • Tire μ, Brake μ • 3 DoF • Trailing link gear model • Ground effect aero

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Antiskid Control Background • Control logic (black box) – Input:

Wheel speed

– Output: Control current • Antiskid valve – Input:

Commanded pressure; control current

– Output: Brake pressure

brakes

brake metering valve wheel speed sensor antiskid control

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Pressure vs. Control Current

Change control in two ways: • Electrically • Hydraulically 21

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HIL Usefulness • Cost-effective • Time-saver • Multi-purpose

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