AAPA automatic polar alignment system mechanical and software overview

Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA) Equatorial Mount Equipment Polar Alignment DIY
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Astrophilos avatar
Astrophilos avatar

AAPA – Astrophilos Automatic Polar Alignment | Mechanical & Software Overview

Hello to everyone I’ve just published a new video where, for the first time, I show the actual azimuth and altitude (ALT) adjustment mechanisms of the AAPA (Astrophilos Automatic Polar Alignment) system, demonstrated in real life on a mount.

In this video I explain:

  • The azimuth adjustment mechanism of the AAPA and how it applies controlled motion to the mount base

  • The altitude lifting mechanism, driven by a stepper motor and linear actuator, converting linear motion into precise altitude correction

  • How both axes work together to correct large initial polar alignment errors

  • The software side and the native N.I.N.A. integration, allowing the AAPA to be controlled directly inside the imaging workflow

The AAPA is designed to start from a rough polar alignment (even with large initial errors) and automatically converge toward arcsecond-level accuracy, minimizing manual interaction and improving repeatability—especially for portable astrophotography setups.

This project is a work in progress: there are still aspects to refine and improve, both mechanically and in software. However, the core design, hardware, and control logic are already working in practice, and this video represents the first complete IRL explanation of how the AAPA functions.

🎥 Video link:
https://youtu.be/51gH6CY0UJg

I’d be very interested in feedback from the AstroBin community, especially regarding:

  • Mechanical design choices

  • Field reliability

  • Possible improvements or alternative implementations

You can check also my other astrobin post about it here: https://app.astrobin.com/forum/topic/209917/stefan-berg-nighttime-imaging-n-astronomy-nina-nina/automated-polar-alignment-system-work-in-progress?page=1

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Willem Jan Drijfhout avatar
Willem Jan Drijfhout avatar
This certainly looks impressive @Astrophilos, and congratulations on the release of your product. It is great to see innovations like this. It's a good time as well. Multiple mount-integrated automatic PA systems have been announced (MLAstro, JWT Astronomy). This could be an upgrade for other mounts. 
The big question I have though is about stability. In your video, it looks like when you're holding the top plate, there is some play in it. For a device that comes under the mount, it has to be as rock-solid as the tripod itself. Any play at this point is highly magnified at OTA level. Have you done any tests to assess flex of the top plate in any way? For tripods there are some standard tests to assess vibration, demping, torsion stiffness etc. Perhaps those could be used in some way?
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Astrophilos avatar
Astrophilos avatar

Willem Jan Drijfhout · Feb 1, 2026, 01:32 PM

This certainly looks impressive @Astrophilos, and congratulations on the release of your product. It is great to see innovations like this. It's a good time as well. Multiple mount-integrated automatic PA systems have been announced (MLAstro, JWT Astronomy). This could be an upgrade for other mounts. 
The big question I have though is about stability. In your video, it looks like when you're holding the top plate, there is some play in it. For a device that comes under the mount, it has to be as rock-solid as the tripod itself. Any play at this point is highly magnified at OTA level. Have you done any tests to assess flex of the top plate in any way? For tripods there are some standard tests to assess vibration, demping, torsion stiffness etc. Perhaps those could be used in some way?

Thank you very much for the kind words and for the thoughtful question, I really appreciate it.

About the stability and the apparent play visible in the video: that is due to the fact that, in the prototype shown, the thrust bearings are not installed yet. At the moment the central rod is only constrained by the screws, so it cannot be fully preloaded in the way the final design allows.

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Willem Jan Drijfhout avatar
Willem Jan Drijfhout avatar
Astrophilos:
Willem Jan Drijfhout · Feb 1, 2026, 01:32 PM

This certainly looks impressive @Astrophilos, and congratulations on the release of your product. It is great to see innovations like this. It's a good time as well. Multiple mount-integrated automatic PA systems have been announced (MLAstro, JWT Astronomy). This could be an upgrade for other mounts. 
The big question I have though is about stability. In your video, it looks like when you're holding the top plate, there is some play in it. For a device that comes under the mount, it has to be as rock-solid as the tripod itself. Any play at this point is highly magnified at OTA level. Have you done any tests to assess flex of the top plate in any way? For tripods there are some standard tests to assess vibration, demping, torsion stiffness etc. Perhaps those could be used in some way?

Thank you very much for the kind words and for the thoughtful question, I really appreciate it.

About the stability and the apparent play visible in the video: that is due to the fact that, in the prototype shown, the thrust bearings are not installed yet. At the moment the central rod is only constrained by the screws, so it cannot be fully preloaded in the way the final design allows.

Ah, makes sense. I've just ordere your files. Not sure yet if I will build it, but intrigued by it and certainly want to support innovative initiatives like yours.
Thank you, Willem Jan.
bigCatAstro avatar
bigCatAstro avatar

In the CAD bundle, do you include a link for the machinist you are using and a link for the stepper motor?

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Astrophilos avatar
Astrophilos avatar

bigCatAstro · Feb 1, 2026, 08:33 PM

In the CAD bundle, do you include a link for the machinist you are using and a link for the stepper motor?

In the files you get the BOM list, with all the components, and in my discord you will find the links for almost everything (aliexpress changes the links almost weekly..). For the machinist is in the video description

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