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Humble Hubble. Team 18 : Evan Foote, Doug Wile, Tim Brown, Derek Pesyna. Background: http://apod.nasa.gov/apod/image/1302/ngc1763_lake_1600.jpg. Abstract.
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Humble Hubble Team 18: Evan Foote, Doug Wile, Tim Brown, Derek Pesyna Background: http://apod.nasa.gov/apod/image/1302/ngc1763_lake_1600.jpg
Abstract The proposed project is a self-aiming telescope. This telescope will obtain its global position and the local time via GPS. It will then automatically orient itself to point at a user selected target (star) using a variety of onboard sensors. Background: http://apod.nasa.gov/apod/image/1302/ngc1763_lake_1600.jpg
PSSCs An ability to establish a coordinate system based on the telescope's absolute global position via a GPS chipset, and relative orientation based on an accelerometer and electronic compass. An ability to compensate for combined variations in the Earth's gravitational and magnetic field, and variations in telescope geometry and mounting configurations via electronic user calibration. Background: http://apod.nasa.gov/apod/image/1302/ngc1763_lake_1600.jpg
PSSCs An ability to retrieve celestial coordinates and targets via Bluetooth from an external host. An ability to automatically move and point the telescope at the designated target using feedback loops from integrated motor encoders. An ability to allow the user to manually override the telescope's target coordinate using an onboard electronic control interface, and to display information regarding headings on an onboard LCD. Background: http://apod.nasa.gov/apod/image/1302/ngc1763_lake_1600.jpg
Component Selection Rationale • All on-board sensors are surface mount and 3-axis. • GPS switched to on-board antenna, but not Bluetooth • CPU selection rationale:
Focus on Motor Control PWM Signal Brake / Coast Enable (High Z)
Focus on 3.3V regulator ON / OFF interrupt Hold Circuit on DPDT Latching Switch
Need to add headers Schematic: Sensor Breakout Board
PCB Layout Main Board Rotary encoders Auxiliary boardheaders Sensor boardheaders RS232 line driver/receiver PIC micro LCD header,shift register VEX encoders
PCB Layout Auxiliary Board 5V, 3.3V, GND Bluetooth + GPSheaders Bluetooth module, 50 ohm antenna 5V, 3.3V voltageconverters GPS receiver H-bridge + power headers H-bridges,associated logic
PCB Layout Sensor Board Gyroscope Accelerometer Compass I2C + powerheaders
Errata • VDD/VSS for I2C and VEX on main board • Replace temporary headers with real headers • Change 100uF capacitor from SMD to through-hole on aux board • Unconnected pins on microcontroller, sensors • Make rotary encoder pads/hole larger
Software Design (Initialization) Start Init. Move to point North Select calb. target Turn on Bluetooth, Connect Telescope points to calb. target Turn on GPS. Get reading Send GPS/time data to Android Accel, compass reading User centers telescope on target Android calcs calibration targets Move to level position Init. Done
Software Design (Main Loop) Start Main Get target from Android Move to target Wait for new target