nmea_navsat_driver ROS package and Emlid Reach GPS units

asked 2018-09-13 08:46:04 -0600

popenc gravatar image

Hey everyone,

I'm having an issue that seems to only show up in a particular stack of software. First off, here's a link to a related post I've made: https://answers.ros.org/question/2900... . This is the same general problem, but since then I've narrowed it down enough to feel like it warranted another post.

I'm encountering an issue that I'm wondering if anyone else has noticed or could sanity check for me. It seems that I can't echo or subscribe to the /fix topic only when I upgrade my GPS's software. I've posted this to the GPS's forums but haven't heard anything yet ( https://community.emlid.com/t/reachvi... ).

Setup:

  • OS - Ubuntu 14.04
  • More OS info - Linux CPR-J100-0057 3.16.0-77-generic #99~14.04.1-Ubuntu SMP Tue Jun 28 19:17:10 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
  • ROS - Indigo 1.11.20
  • GPS Package - nmea_navsat_driver 0.4.2
  • GPS unit - Emlid Reach RS, ReachView app 2.11 or greater (I have 2.14 at the moment) plugged into computer with USB.

Issue:

When I run the nmea_navsat_driver's serial node, I can see the /fix topic with "rostopic list," and I can see it's being published by the serial node with "rostopic info /fix," but when I try to echo the messages or subscribe to them in another node, it hangs up indefinitely.

Workaround:

Oddly, if I downgrade Emlid's ReachView application to version 2.10 or lower, this problem resolves itself and I'm able to echo and subscribe to the /fix topic. If I upgrade to 2.11+, the issue comes right back.

Conclusion:

Uhh, I'm not really sure where this problem lives. I mostly wanted to see if anyone has encountered this, or if someone would be bored enough to try and replicate the issue. Also, I want to note that I'm a bit tied to the old Ubuntu and ROS versions because the robot we're using came with them and their firmware is a little too tied to ROS upgrade without breaking stuff.

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Comments

I can see the /fix topic with "rostopic list," and I can see it's being published by the serial node with "rostopic info /fix,"

Note: rostopic info /fix shows you there is a publisher for that topic, not that anything is being published to it.

The rest of your description makes it ..

gvdhoorn gravatar image gvdhoorn  ( 2018-09-13 13:46:58 -0600 )edit

.. sound like nothing is being published.

If you want to be sure, edit the source code of nmea_sat_driver to output a log msg (ROS_INFO(..)) each time it actually publishes something to fix.

gvdhoorn gravatar image gvdhoorn  ( 2018-09-13 13:47:43 -0600 )edit

Btw, I see that you also posted ros-drivers/nmea_navsat_driver#53.

Cross-posting like that is considered bad form. Could I ask you to please not do that?

gvdhoorn gravatar image gvdhoorn  ( 2018-09-13 13:48:46 -0600 )edit

Sorry, I didn't realize it was bad form. I closed it over there. About the nothing being published, I can see data coming in if I print it to the terminal, just not when using with ROS. I'll try what you suggested.

popenc gravatar image popenc  ( 2018-09-13 14:12:37 -0600 )edit

About the nothing being published, I can see data coming in if I print it to the terminal

that is nice, but doesn't help us. If the format of the data output by the unit is changed because of the firmware upgrade, the ROS node could become incompatible. That could lead it to not publish. ..

gvdhoorn gravatar image gvdhoorn  ( 2018-09-13 14:13:38 -0600 )edit

.. that is what we're trying to establish here.

I've just checked and the driver is Python only, so changing it should be trivial. Just clone it in your workspace and edit the files. Then build and source.

gvdhoorn gravatar image gvdhoorn  ( 2018-09-13 14:14:19 -0600 )edit

Ok, that makes sense. I'll just close this for now, and put an answer up if I find one.

popenc gravatar image popenc  ( 2018-09-13 14:18:39 -0600 )edit

I don't think this needs to be closed: it's a perfectly valid ROS Answers question.

Please try instrumenting the driver and please report back with any results.

This way future readers may also benefit from this question.

gvdhoorn gravatar image gvdhoorn  ( 2018-09-13 14:59:20 -0600 )edit