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Raytheon Seekers

Infrared Seeker Calibration Mechanism

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Raytheon Seekers

Aaron Scrignar……Team Leader

Eric Draves………..Historian

Trevor Moody…….Web Page Des., Mediator

Stacy Davison……..Document Coord., Financial

Officer

LaTanya Williams…Communicator

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Presentation Outline

• Client Description

• Problem Definition

• What is Infrared Imaging?

• Project Requirements

• Design Method

• Prototype Design

• Analysis Process

• Project Spending

• Time Log

• Conclusion

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More about… • One of the largest defense electronics contractors in the world.

Leader in defense electronics, including:– Missiles; Radar, Sensors and Electro-Optics– Intelligence, Surveillance and Reconnaissance (ISR)– Missile Defense

• Chairman & CEO: Daniel P. Burnham• 2002 Revenue

– $16.8 Billion– 62% of sales to U.S. Department of Defense

• 79,000 employees worldwide• Headquarters located in Lexington, MA

Raytheon

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Client Contact

• Brian Scott– B.S.E. in Mechanical Engineering at NAU– M.S. in Mechanical Engineering at UofA– Employee of Raytheon since graduation

• Missile Systems – Future Combat Systems

• Tucson, Arizona

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Problem Statement

A preliminary design and a proof-of-principal prototype are needed for a window positioning system to be used in a tank-launched projectile. The device must position a small germanium window into an infrared sensor’s optical path to perform Non-Uniformity Compensation.

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Project Requirements

NUC Mechanism must:• Survive 10KG launch acceleration normal to the

window face• Packaged in 0.235” thick by 2.89” diameter cylinder,

excluding electronics• Move a 0.50” x 0.44” x 0.04” thick Germanium lens to

cover a photocell array• Require less than 24 Watts at a maximum of 24 Vdc for

less than 1 second• Move lens in and out of the field of the array in less than

1 second, and remain in position for 1 second

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What Is Infrared Imaging

• Light at frequencies below visible red are considered infrared

• All objects emit infrared energy at ordinary temperatures

• Objects with higher temperatures emit more infrared energy

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Infrared Seeker Operation

• Modern “Heat Seekers”:– Employ advanced

infrared sensor arrays

– Utilize computer programs to select, target, and guide munitions towards specific images

Non-Uniformity Compensation (NUC)

Germanium Lens Moved in Front

of IR Array

NUC is necessary to adjust for different pixel sensitivities which could cause erroneous targeting by seeker computer

Raw IR Image before NUC

Blurred IR Image with Lens in Position

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Non-Uniformity Compensation (NUC)

Computer algorithm adjusts gain factors of individual pixels so that a uniform image results from a uniform scene

Germanium Lens MovedOut of Position

NUC

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Seeker Head Layout

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Rail Gun Test

• 155mm Howitzer fires projectile into water filled trough to provide firing conditions and “soft catch capability

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Acceleration Time Histories

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• Launch Conditions– Set Back 10,000G

– Set Forward 2,000G

– Lateral Balloting 3,300G

• Flight Conditions– Lateral: 0-3G

– Vibration: 5G

Acceleration Definition

Set Back

Lateral Balloting

Set Forward

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Scope of Design Constraints

• One quarter subjected to 10,000 G’s weighs

approximately 120 lbs.

• The restricted thickness of the available volume is less than ¼ of an inch

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Design Philosophy

• K.I.S.S.- Minimize complexity of the design to reduce

probability of failure

• Keep close contact with client – Bring attention to potential design problems

before it’s too late

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Design Process

• Brainstorming - Mechanism ideas

• Mechanism Selection - Based on size constraints

• Modeling - Cardboard & CAD models to assess geometries

• Analysis - Hand calculations, Adams, COSMOS/M

• Fabricate Prototype – CNC

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Final Design

• Frame

• Solenoid

• Positioning Arm

• Pin

• Bushing

• Return Spring

Final Design

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Frame Design

• Frame supports components and other seeker optics– Modified to eliminate unnecessary weight – Recessed regions for return spring and

counterweight clearance

Frame Design

• Frame– 6061-T6 Aluminum

– Sult = 45 ksi

– CNC work done by R&D Specialty Manco– Phoenix, Arizona

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Selected Solenoid

• 3 VDC pulling solenoid – Electro Mechanisms, Inc

– Commercially available PO-25

– Fits within required dimensions

– Provides minimum of 2 oz. of force at 3X nominal voltage (18 Watts)

Positioning Arm• Positioning Arm

– 7075-T6 Aluminum

– Sult = 82.7 ksi

• Pin– AISI 4130 Steel

– Sult = 106 ksi

• Bushing– Oilite Bronze - Oil

Impregnated

– Self Lubricating Bushing

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Pin Connection Design

Press Fit Withstands 120lb Vertical Force

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Analysis Justification

• Deformation of surfaces are within tolerances defined by the optical engineer

• Deformation of support structure for optics is within tolerance and creates no interference– No yielding through cross section of part

• No ultimate failures occur

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Analysis Focus

• Static Analysis– Pin joint withstands launch accelerations

– Arm deflection does not produce ultimate failure

• Dynamic Analysis– Solenoid and spring actuation times

– Verification of solenoid adequacy

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Finite Element Analysis

• COSMOS/M – 3-D 20 Noded Quadrilateral Elements– Body (Acceleration) Load

• Modeled Positioning Arm & Components– 7075-T6 Al Arm– Germanium Lens– Oilite Brass Bushing– Tungsten Counterweight

• Material properties specified for each component

FEA Mesh

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Von Mises Stress Plot

max = 80.3 ksi

F.S. = 1.03

Does Not Yield Through Cross-Section

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Dynamic Analysis

• Adams software used for dynamic analysis w.r.t. arm rotation

• Employed actual solenoid force function curve and spring force

• Analysis Performed:– Actuation & return times– Forces due to snubbing of

arm rotation– Verification of solenoid

strength sufficiency over entire actuation distance

Adams Simulation

Actuation time = 0.027 sec Spring Return = 0.028 sec

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Prototype Cost

Machine Work & Parts

Frame (2)

Arm (2)

Pin & Bushing (2)

Solenoids (14)

Solenoid Screws (144)

Miscellaneous (Spring, Wire, etc.)

$ 450.00

$ -

$ 115.00

$ 89.92

$ 24.00

$ 5.00

TOTAL $ 683.92

Cost Per Unit $ 341.96

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Total Project Spending

Modeling Supplies $ 42.00

Prototype Cost $ 683.92

Documentation $ 400.00

Presentation Supplies $ 50.00

Travel & Miscellaneous $ 730.00

TOTAL $1,905.92

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Project Budget

• Provided Funds by Raytheon– $ 3,000

• Total Project Spending– $ 1,906

• Donation to the College of Engineering & Technology

– $ 1,094

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Time Log

Total Project Hours for Spring Semester 684.5 hrs

Avg. Hours Per Team Member: 136.9 hrs

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Conclusion

• The balanced swing arm design is simple and efficient in providing the required lens motion while withstanding the environmental constraints

• A prototype that meets project specifications will be delivered to Raytheon on time and within budget

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Acknowledgements

• Brian Scott– Raytheon Missile Systems

• Dr. Ernesto Penado, Advisor

• Dr. David E. Hartman, P.E.

• Dr. John Tester

• NAU Machine Shop– Don McCallum, Daniel, & Rus

Questions?