Ground Control

Andrew BourgeoisAaron Minard

Contents

Background Satellite Tracking SatPC32

Problem Statement Solution Mechanical Design System Diagram Electrical Design Software Schedule Budget

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

EGIS Rotor and Control

Equipment-Gesellschaft für Internationale Elektronik Systeme

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

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

SatPC32

Screen Shot of SatPC32 in use

WinListen predicts path

Problem

Track a low orbit satellite such as a CubeSat from horizon to horizon is as little as 30 seconds180°/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

Solution

Gears and motors, motor controllers Freescale Coldfire 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

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…. ?

Position Sensing

Specified previously 1° step size = at least nine bit

resolution29 = 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

System Diagram

Micro-controller

EL - Motor

ControllerAZ -

Motor Controlle

r

Limit Switches

RS232

SatPC32

PositionEncoders

Electrical Flow

Position Encoders

AC

Motor Controlle

r

Motor Controlle

r

12Vdc10Amp

FUSE

5Vdcregulat

or

Micro-controller

A

E

Circuit Protectio

n

12Vdc10Amp

FUSE

PC Running SatPC32

Limit Switc

h

Limit Switc

h

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

?

Check Encoder

s?

ReadSerial

Read Encoders

Micro Controller Connections

Check Serial Code

Schedule    Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week 12 Week 13Week 14

Mechanical                              

                             

                             

                             

                             

                             

                             

                               Final Mounting of all                            

Electrical                              

 Coldfire Peripheral Boards                            

  Power Supply Wiring                            

 Motor Drivers to DC Motors                            

  Sensor Wiring/Positioning                            

Software                              

  SatPC32 Research                            

  Serial Port Code                            

  Encoder Code                            

  Motor Controller Code                            

  Code Integration                            

  Testing                            

Schedule

Week1 Week2 Week3 Week4 Week5 Week6 Week7 Week8 Week9 Week10 Week11 Week12 Week13 Week14

Mechanical

  Final Mounting

Electrical  

 Coldfire Peripheral Boards

 Power Supply Wiring

 Motor Drivers to DC Motors

 Sensor Wiring/Positioning

Software  

 SatPC32 Research

  Serial Port Code

  Encoder Code

 Motor Controller Code

  Code Integration

  Testing

Budget

Questions?