Future of ROS 2 GPS Support

ROS ROS General
6

We’re heavily relying on RTK gnss data for our tractors.

Some notes:

  • We’d welcome a message format which includes orientation.

  • ‘Hack: Just keep going off the same UTM zone, slightly inaccurate but “shrug"’

    • This is exactly what we do. For us this is accurate enough.

  • UTM zone jumping: Please note that this not only jumps in X and Y but also yaw. We have issues with this in the current navsat_transform implementation.

  • “We assume that we are creating tangent planes off of the robot’s initial position”

    • One should be careful with this. A robots initial position can be a very random one. If during an operation a reboot is performed, all 2d positions are shifted. Leading to:
      • Different accuracies than before the reboot
      • Very difficult to create position plots (plotjuggler) as all positions are different now
      • The same repetative task cannot be compared 1-to-1 as signals depend on the initial startup position
    • Sticking to a fixed defined zone (UTM) solves this mostly. Although near the border there is still a change the last reboot was in a different zone leading to the same problems as above. So it’s not the holy grail.

  • “Supporting wgs84 vs nad83”

    • In my experience this is a non-issue. By applying RTK streams for example, the lat,lon values are modified/fixed to the ‘local’ coordinate system. In Europe for example ETRS89.
      This fix is done before any of the transformations talked about in the proposal, so out-of-scope?

All things considered, I’m happy to see this is getting some serious traction! Thank you all for the effort.

PS. While modifying things, shouldn’t we stick to the term GNSS instead of GPS as it’s just one of the implementations (Galileo is another one for example).

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