Star Tracker V2
A while ago, I posted harmonic drive based star tracker. I complained at the time that it needed improvement to allow for better polar alignment. Well, here it is! Star Tracker Version 2!
This star tracker now features 3 harmonic drives. One for each axis; Azimuth, latitude, and rotation. It’s quite obvious where the drives are since they’re quite large cylinders.
The bottom cylinder is the azimuth control, it allows for the tracker to be pointed North or South (in my case South). There’s a long stick that comes off it which mounts a compass. Originally the system was going to be a closed loop with an Arduino magnetometer acting as the compass. However, it was quickly found that the magnetometer was very unreliable. So, I had to modify the mount to hold a traditional compass instead.
The next cylinder mounted on the azimuth cylinder controls the latitude. This too was going to be programmatically controlled, with the stepper moving a precise number of steps to reach the correct latitude. However, I realised that this number would need to be modified depending on the levelness of the terrain. So instead, I opted for a manual system using a digital spirit level.
The final cylinder is the one that rotates with the stars. This cylinder was originally taken from the V1 star tracker, but I soon found cracks and unevenness in its rotation. So, I redesigned it and rebuilt it.
The whole thing was 3D printed and assembled with M3 screws and lock nuts. An Arduino with a CNC shield acts as the controller.
