ArduinoDomeController

An astronomical observatory dome controller based on two Arduino boards.

• The main controller (DomeController)

• The shutter controller (DomeShutter)

  

Main controller

The main controller is connected to a PC by a USB cable. It uses the MaxDome II serial protocol for compatibility with existing software.

Azimuth angle is read by an optical encoder connected to a rubber wheel that rotates with the dome. A hall probe is used to detect the "home" mark, wich serves as an absolute reference for azimuth angle.

The dome is driven by a three-phase motor powered by a variable frequency drive (VFD). Three digital Arduino pins control the VFD through NPN transistors, which are connected to the following terminals in the VFD:

• Clockwise motion
• Counterclockwise motion
• Jog (slow motion)

For more details, read the definitions in DomeController.ino.

Shutter controller

The shutter controller is mounted in the rotating dome and it is powered by a 12v lead-acid battery. The battery can be charged with

• a solar panel (the solution I am using).
• a trickle charger wich is connected to the battery when the dome is in the home position using two brushes.

The shutter controller communicates with the main board by means of a serial radio link created with HC-12 modules.

Shutter and flap DC motors are controlled by a Monster Moto Shield.

Five limit switches are used. Pin numbers are defined in DomeShutter.ino.

• Shutter closed
• Shutter fully open
• Flap closed
• Flap fully open
• Flap and shutter mechanical interference

The 4-button keyboard in the shutter controller is read using only one analog pin.

For more details, read the definitions in DomeShutter.ino.