P11310: Parabolic Dish Autopoint Solution

Project Family Team Leader: Trae Rogers (ME) Project Engineer: Pat Ryan (EE) Kyle Norlin (ME) Chris Reed (CE) Ric Schmeelk (EE)

Start Term 2010-1

End Term 2010-2

Faculty Guide Mr. Ed Hanzlik

Primary Customer L-3 Global Communications

Project Description

• Currently the L-3 manpack systems are manually pointed. The desired system is to have a geared mechanism that rotates the dish to point automatically. We have delivered a prototype that will support a 24” parabolic antenna that will point to a geosynchronous communication satellite. Interaction with the system is through an Ethernet connected laptop and requires minimal human interaction. This project has proven that this platform can be automated.

Concept Description and R ationale

• Competitive Benchmarks• Generate Product Concepts• Customer Needs and Specs Limit Concept Ideas• Selection Matrix

Antenna Autopoint Criteria 1 2 3 4

Azimuth assembly Turntable Wheels

Elevation assembly L-bracket Hinge rotation Pulley

Automate Motor Servo Stepper

Azimuth sensor Shaft encoder Compass Shadow

Elevation sensor Shaft encoder Angle sensor

Heading GPS Compass Sextant and clock

Fault detection Current loop Current shunt Shaft encoder

Level detection Tilt sensor Gyroscope Hand level

Fault display LEDs GUI Buzzer Ed yells

Customer Needs/SpecificationsNEEDS

• Portable – Low weight – Small size – Low power consumption

• Usable setup time • High degree of pointing accuracy • Low cost • Test procedure to verify functionality • System Health Status

– LEDs • Fault status • Movement status • Power status • Blackout mode

– GUI • Fault status • Movement status • Power status • Level status

• Robust design

SPECIFICATIONS

· 15 Lbs Max Weight

· 150 Watt Max

· 24 VDC Max

· 3 Minute Acquisition Time

· +/- 0.75° Pointing Accuracy

· $5000.00 Budget

R isk # Subgroup Risk Family R i skLikelihood

Severity

Importance

Means to mitigate Owner

1A Systems Overall System Tolerances Greater than +/-0.75 deg Turntable bearing tolerance too great 1 3 3 Allocate bearing tolerance in proportion to distance such that if

does not add more than .1 deg inaccuracy to system Trae/Pat

1B Manufactured Part variance, e.g. hole locations 2 2 4 Hold each dimension to 3 mil tolerance Trae/Kyle/Pat

1C Mechanical movement anticipated deviates from actual (back lash in gears) 2 3 6 Use sensors (shaft encoder - az, inclinometer -el) to detect turn

table and arm actual position Pat/Ric/Chris

1D Arm Deflection causes misalignment 1 3 3 Calculated FEA to help prove strength. Trae1E Wear on shaft couples causes misalignment 1 3 3 Adding flats/set screws to couples and gear and motor shafts Trae/Kyle

1G Input through Program does not match theoretical output 2 2 4 Test and debug/ shaft encoders, inclinometers Chris

1I Customer Specs not met Weight of total system exceeds 15 lbs 1 2 2 Took weights into account during design process Trae/Kyle

Wattage exceeds 150 Watts 1 2 2 Research on different types of motors/motion controllers Pat/Rick/Chris

Budget exceeds $5,000.00 1 1 1 Detailed BoM during design, and researched different providers for the best prices Trae

3A Electrical Components damaged Motor jams, draws too much current 2 2 4 Apply breakers on power lines sized to what can be considered operational current range of motors. Initial value 1 Amp Ric/Pat

3B Short occurs somewhere in electrical systems 3 1 3 Circuit Breakers/Setting current limits to power supplies Ric/Pat

3D Electrical Surge/Electrical Noise 2 3 6 Use diodes and capacitors to protect sensitive parts. Use as needed Ric

4A Mechanical Components damaged During tests wear on couples and shafts take place. 1 1 1 Calculated FEA to help prove strength. Kyle4B Motor mounts bend while motor runs 1 3 3 Calculated FEA to help prove strength. Trae4C Too much friction on turntable bearing 2 1 2 purchased oil-lite sleeve bearing Trae4D Drop causes damage to system 2 3 6 Handled with care Team

4E Contaminants get into bearing sleeve causing binding 2 1 2 Fit as tight as possible with housing protection Trae/Kyle

5A Electrical Exceed Electrical Specs Current draw too high 1 2 2 Design motor speeds to allow for optimum current draw and setup time Ric/Pat

5B Deadlines not met Lead time on Ordered Parts is too high 1 3 3 Have everything ordered by week 2 Trae5C Brinkman Lab does not deliver on time 2 2 4 Met with John Bonzo to get parts in ASAP. Trae5D Electric and Mechanical incompatible 2 3 6 Wire schematics match with Detailed designs. Team

6A Software System Fails Test GUI is too complicated for user 2 2 4 Talked to L3 about what types of inputs need to be included in the GUI, and having a new user try it in the test plan Chris

Software becomes too complicated due to having to resort to serial cable instead of Ethernet cable 3 3 9 Communicating with L3 when there are issues, and reading the

data sheets for ethernet cable usage Chris

High R isk Assessment

3D Design/Architecture

Tests

Azimuth Test

Azimuth & Elevation Test

Current State of Design

• Approx. 0.25 Degree Backlash in Elevation• Approx. 1.70 Degree Backlash in Azimuth• Full GUI Interaction and Integration• Approx. 16.75lbs• Max of 24VDC, 3 Amps, 72 Watts

Summary• What was asked:

– Provide a robust autopoint solution which meets accuracy, SWAP requirements within budget, in an easy to use form. Pointing solution should be realized within a reasonable amount of time.

• What we did:– Delivered a proof of concept within budget which meets elevation accuracy,

size, and power requirements with a simple GUI. The system easily reaches maximum positions in minimal time.

• Where we fell short:– Azimuth accuracy still a problem with regards to repeatability.– Weight slightly over requirements, but could be brought down.– Auto-correction of position based on sensor feedback.– Elevation actuation is physically noisy.– Fault light configuration

Where we fell short• Azimuth accuracy still a problem with regards to repeatability.

– Key stock does not meet high enough tolerances through the gearbox– Gear ratio could be increased as well as physical size of gearbox– Stainless steel turntable mount could decrease friction

• Weight slightly over requirements, but could be brought down.– Mechanical components could be improved to reduce weight

• Auto-correction of position based on sensor feedback.– Verify sensors (encoder and inclinometer)– Change microcontroller code to handle position of the dish– Sensor Location

• Elevation actuation is physically noisy.– Motor mount to lift motor off the turntable– Possibly optimize the acceleration and velocity of the motor– Look into servo motors

• Fault light configuration– Microcontroller code needs to process the information for the LED’s

Overall Project Evaluation

• Able to prove that an Autopoint Solution can be done at reasonable SWAP.

• Good team experience.• R eal Life Scenarios• Customer needs/specs were satisfactorily met.• SUCCESS!

Opportunities/Suggestions

• Always include a factor of safety.• Look into a real time OS for microcontroller

operation.• Learn from your failures.• Integrated electrical system.• Larger Azimuth Gearbox• Consider Different Arm and Dish Design

Structure

Thank You

• QUESTIONS?• COMMENTS!