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[Ignition Edifice] Newbie misunderstanding gazebo topics ?

asked 2021-06-12 07:06:50 -0500

BigMassive gravatar image

Hi everyone,

[Ignition edifice, installed by binary on Ubuntu 20.04]

I'm trying to work through the tutorials in an attempt to understand the codebase. I may be misunderstanding how gazebo works - some pointers would be appreciated.

I've got a basic diff-drive robot example generally working. A Key Publisher and Triggered Publisher seem to work together - the model / simulation responds.

However, (see below), if I call

ign topic --list

multiple times, I seem to get different results.

If I then call something like this directly from the command line

ign topic -t "/cmd_vel" -m ignition.msgs.Twist -p "linear: {x:0.5}, angular: {z: 0.05}"

sometimes it works, but, more often, it does not. (The key publisher / triggered publisher combo in the simulation itself does seem to work all the time).

I was expecting the list of topics to remain the same (at least with nothing else happening). I'd expect the calls to this topic from the command line to have an effect all the time, or at least come back with some kind of failure message / timeout. This seems a bit nondeterministic.

Maybe as a newbie I'm just expecting the wrong thing. Pointers would be appreciated.

Otherwise, any steers on how to 'debug' what's going on, or not get into this state in the first place, would be helpful.

Thank you

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could you please edit the question and include the launch command you are using so I can try to reproduce the issue? Thanks.

Jose Luis Rivero gravatar imageJose Luis Rivero ( 2021-06-15 10:26:48 -0500 )edit

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answered 2021-06-16 12:04:34 -0500

temero gravatar image

I've had kinda the same issue. I've had tutorial simulation running in one terminal window, was publishing tutorial msgs in another terminal window, and was echoing the corresponding topic in 3rd window. And about 40% of the messages that I sent were missing in the topic echo terminal and didn't affect the simulation. I've had binary installation of Ignition Dome inside the virtualbox'ex Ubuntu 20.04.

After I've installed Ubuntu directly on the PC, I didn't seem to find this problem anymore. Not sure if this was relating to the problem or something else.

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Asked: 2021-06-12 07:06:50 -0500

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Last updated: Jun 16