Ground Control

1. Andrew Bourgeois Aaron Minard Ground Control

2. Contents • Background • Satellite Tracking • SatPC32 • Problem Statement • Solution • Mechanical Design • System Diagram • Electrical Design • Software • Schedule • Budget

3. Background • VTC developing Cubesat, transmits data • Have to follow Cubesat to receive data • Existing 3-meter parabolic dish antenna • Low orbit satellite revolves around earth in minutes, seen for short time per orbit • Many existing solutions • EGIS Bi-axial antenna positioning system • BIG-RAS Azimuth and Elevation Rotator

4. EGIS Rotor and Control • Equipment-GesellschaftfürInternationaleElektronikSysteme • Cost: • Software $400 • Data Interface $1,100 • Hardware $2,700 (EL-40°, AZ-180°) • Extension $2,200 (EL-90°, AZ-360°) • Rotor Hardware Mount $400 • Satellite Dish Mount $400 • Total $7,200

5. SatPC32 • A free software available online for tracking satellites. Updates on screen and controls rotor to point to position satellite • Uses orbit of satellite and observer position • Many types of rotors to select for output • Uses Serial port or Parallel port on PC

6. SatPC32 WinListen predicts path Screen Shot of SatPC32 in use

7. Problem • Track a low orbit satellite such as a CubeSat from horizon to horizon is as little as 30 seconds 180°/30 seconds=6°/sec • Move a 3 meter satellite dish • 360° Azimuth (left/right) • 90° Elevation (up/down) • Interface to PC running SatPC32 • Integrate/improve previous design

8. Solution • Gears and motors, motor controllers • FreescaleColdfire 32-bit Microcontroller • Serial interface with SatPC32 using EGIS controls and a serial port • Position sent as ASCII Characters • :P AZ=123.45 • :P EL=009.87 • Magnetic Encoders measure position of dish • Use/Modify existing designs for elevation and azimuth control

9. Mechanical Stuffffffffffffffffff • Maybe some Azimuth (talk about using last years stuff that was good?) • Maybe a whole slide summarizing last years model and then discussing what we liked (Azimuth) and what we thought needed improvement (Elevation) • We liked work gears for both… why? (speed) • Discuss around here about the wind force calculations….? Angular acceleration…. ?

10. Position Sensing Specified previously • 1° step size = at least nine bit resolution 29 = 512 steps 360 deg/512 steps = .7 deg/step • 6°/sec = 1 rpm (6°/sec)(60sec/1min)(1rev/360deg) • Magnetic shaft encoder • Absolute position sensing • Small size, large operating temperature range • Analog output from 10-bit DAC • 1024 steps or .35°/step

11. System Diagram SatPC32 EL - Motor Controller RS232 AZ - Motor Controller Micro- controller Position Encoders Limit Switches

12. Electrical Flow A Micro- controller Position Encoders PC Running SatPC32 E 5Vdc regulator 12Vdc 10Amp Limit Switch Motor Controller Circuit Protection FUSE AC 12Vdc 10Amp FUSE Limit Switch Motor Controller

13. Software (Microcontroller) • Decide where to turn, how fast • Read new position from serial port • Stores values when they come in • Read actual position from encoders • Measure periodically • Always checking limit switches • If ever activated, stop motors Controller (Set Outputs) New Serial? Read Serial Check Encoders? Read Encoders

14. Micro Controller Connections

15. Check Serial Code

16. Schedule

17. Schedule

18. Budget

19. Questions?