PX4 Sapog, Zubax Orel, Zubax GNSS 2 status update


This post announces recent noteworthy developments in some of our projects.

The observations we made since the announcement of Zubax Orel 20 (a Sapog-driven ESC) led us to believe that people tend to have serious misconceptions about power capabilities of ESC. A possible reason for that is the abundance of Chinese low-quality ESC that tend to have much lower actual power capability than advertised. Here at Zubax we termed it power capability inflation. In order to prevent our customers from having incorrect understanding of the true power capabilities of Zubax Orel 20 (pictured on the right), we strongly suggest to model and verify your application using ECalc: http://www.ecalc.ch/xcoptercalc.php.

As was promised a couple months back, the reference hardware design for PX4 Sapog has been released under CC BY SA 3.0. The design files (in Eagle format) are available in the official PX4 Hardware repository on GitHub. We're encouraging third parties to develop their own hardware ESC designs based on this reference. Feel free to stop by our brand new Gitter channel if you have questions.

Besides the above, Sapog had another development: we've released a number of important improvements, mostly concerning stability of the spinup algorithms. The release binaries can be downloaded from files.zubax.com and installed via UAVCAN or DroneCode Probe.3689703507?profile=original

Zubax GNSS 2 has received a firmware upgrade too. A few users reported that they're having difficulties calibrating the compass with PX4 or APM. An investigation uncovered that the difficulties were caused by 2 factors:

1. The measurement range was not sufficiently wide to account for all valid use cases. This was fixed in the firmware.

2. APM and PX4 somewhat mishandle external compasses by making invalid assumptions about their measurement ranges. We added a configurable scaling coefficient that allows to reduce the magnitude of the output magnetic field vector, silencing the warning from the autopilot. Learn more from the docs at docs.zubax.com.

The fix is available in firmware version 3.1, you can get it from files.zubax.com. If you're not using the compass, there's no need to upgrade.

Useful links:


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  • Thanks!

  • Thomas, I've exported the schematic to PDF and uploaded it here for convenience: https://files.zubax.com/docs/sapog_reference_hardware.pdf

    Rob, it's true that eCalc is not a silver bullet. Also true that 20A is clearly not a one-size-fits-all solution. The point I was trying to make is that such power capability fits a much larger set of applications than is commonly believed.

  • @Thomas, seems the schematic and board files (Eagle format) are available from the PX4 github page:


  • How about posting a PDF of the schematic somewhere? Thanks!

  • Yeah yeah ...

    Ok, nice! ;)

  • Sorry, need it to fly properly. :)

  • Just replace with an octo and divide by 8.


  • I need 160 Amp.

    eCalc is not terribly accurate, and misses quite a lot of issues.  It is only one tool in the engineering toolbox. 

  • We need an 80amp ESC not a 20amp!

  • I was under the impression eCalc does empirical testing to determine the numbers they use rather than simply using the listed specs from a supplier.

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