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Joel Handy Rob Schugmann Jon Addison

C ONTROL S YSTEMS D ESIGN F INAL D ESIGN R EVIEW. Joel Handy Rob Schugmann Jon Addison. T EAM 7. S TAR S EARCH. Final Design Outline. Final Design Outline. Project Motivation Project Goal & Problem Statement Design Concerns & Specifications Component Selection. Project Goal

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Joel Handy Rob Schugmann Jon Addison

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  1. CONTROLSYSTEMSDESIGN FINALDESIGNREVIEW Joel HandyRob SchugmannJon Addison TEAM7 STARSEARCH

  2. Final Design Outline Final Design Outline • Project Motivation • Project Goal & Problem Statement • Design Concerns & Specifications • Component Selection

  3. Project Goal • Design a self-calibrating computer-positioning telescope using a pan-tilt mechanism to track a celestial object • Should be easy to use while remaining relatively cheap to implement • Problem Statement • Create a telescope that can calibrate itself to a zeroing point and track specific celestial objects based on published scientific data • Should withstand disturbances and stay centered on the desired object Project Goal / Problem Statement

  4. Design Concerns & Specifications • Speed • Resolution • Noise (Disturbance) Rejection • Gear Backlash Compensation

  5. Speed Speed • Specifications for • Specifications for Tracking Speed • 360°/23.93446743 hrs. • 15°.04107000 / hr. • 15".04107000 / sec.

  6. Resolution Resolution Resolution is the smallest movement possible in a system High Resolution Requirements - 0.5 arc seconds for astrophotography - Greater flexibility for typical viewing, but the requirements are still high - Increase resolution by gearing down the system

  7. Resolution Noise Rejection • Resolution is the smallest movement possible in a system • High Resolution Requirements • - 0.5 arc seconds for astrophotography • - Greater flexibility for typical viewing, but the requirements are still high • - Increase resolution by gearing down the system

  8. Gear Backlash Gear Backlash • Backlash is the amount of mechanical looseness in the positioning drive system • When gears are used, this looseness is attributed to spacing between the teeth of the meshing gears

  9. Gear Backlash Continued Gear Backlash Cont • A balanced telescope combined with a slight friction will help the accuracy of the system by causing the backlash to always be in the same direction. • When the instrument has no friction and is totally balanced, there may be a tendency for the backlash to shift from one side to the other as the center of gravity shifts throughout movement.

  10. Commercial Products • 3 Basic levels of complexity • Motors geared down to rotate a telescope at the same speed with which the earth rotates • Error Correction – motor used to focus telescope so user does not touch it • Locks on a random star in its photo sensors field of vision and tracks the movement of said star • User must calibrate, No noise rejection • The most advanced systems use banks of published data to send desired angles to both motors • No noise rejection, calibration dependent on guide stars Commercially Available Products

  11. Motor Selection Motor Selection • Motor (Pittman GM8724S016) • Most feasible (expensive but has a 19.5:1 gear ratio) • High internal gear ratio allows us to use small gears to get a 4:1 gear ratio • Cost: $112.26

  12. Motor Selection Alternatives • Researched other motors to compare with our selection • Found several cheaper motors that could provide enough power with larger gears • Savings = $10 – 20 per motor • The added cost of buying larger gears to compensate for the difference in power output offset these savings • Larger gears affect telescope mounting Motor Selection Alternatives

  13. Gear Selection Gear Selection • Motor (Pittman GM8724S016) • Most feasible (expensive but has a 19.5:1 gear ratio) • High internal gear ratio allows us to use small gears to get a 4:1 gear ratio • Cost: $112.26

  14. Compass Sensors Compass Sensors • PNI Corp. Vector-2x Magnetometer • Cheap ($50), accurate in any environment to within 2 degrees • Dinsmore 1490 compass • Also cheap ($14), not that accurate • Magellan 310 GPS • Expensive ($150), accurate to within a degree

  15. Inclinometer Sensors Incl. Sensors • US Digital T4 Incremental Inclinometer • cost ($70) • reports angle of an object with respect to gravity • CrossBow CXTILT02E • cost (~$500) • accurate to within 0.4 degrees

  16. Motor Torque Constraints Kp1 = -2.6 Kd1 = -0.5 Kp2 = -1.5 Kd2 = -0.1

  17. Settling Time Constraints

  18. Project Cost Project Cost Motors (2) $112.26 each Gears Small (0.506’’) (2) $ 7.16 each Large (2.066’’) (2) $ 17.00 each Timing Belts (2) $ 3.16 each Compass Sensor (1) $ 50.00 Inclinometer Sensor (1) $ 70.00 Telescope (1) $150.00 Total $392.84

  19. Total Cost Total Cost $272.84 without sensors or pulleys

  20. Plan of Action Plan of Action • Finalize the simulation • Order the appropriate parts (motors, gears, and pulleys) • Assemble the system • Design and optimize our controller

  21. Schedule Schedule • February • Finalize design • Simulation & Controller tuning • Order parts

  22. Schedule Schedule • March • Construct system • Perform experiments to determine exact inertia • Write real-time code

  23. Schedule Schedule • April • Continue testing and tuning the code • Tune / Optimize the controller • Final Demonstration

  24. Questions Questions?

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