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Debugging when all Links snap to origin

asked 2016-01-08 23:02:42 -0500

I'm wondering how I can debug my robot/code when the symptom is all links snapping to the origin. There are no error messages printed with --verbose. I'm not sure whether it's a function of my SDF, or my code controlling it

Here is the model

Here is the code

the motor plugin I'm using is here

Although the code is WPILib code and probably won't make any sense to anyone.

If I just put in the model with no code running, it doesn't explode. I can drop it and move it all around and it works. It seems to be something with my code or plugins, but I just don't know where to start.

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answered 2016-01-09 20:46:15 -0500

I've uncovered the issue. It appears I was turning Java's NaN into a protobuf float64 message. This ended up translating to a force -2000 on some of the joints. Can anyone shed light onto why this would cause everything to snap the origin? Those are large but not impossibly large forces...?

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it probably not that large at the beginning, but it might grow a lot in the proceeding simulation steps (you might be able to visualize this if you pause and then step into the simulation)

AndreiHaidu gravatar imageAndreiHaidu ( 2016-01-11 04:01:46 -0500 )edit

Printing out the forces show it's truly only -2000. Good suggestion with the stepping. Unfortunately, I can't pause it quickly enough...I've resolved the issue of ever sending NaN which is the real problem here

Peter Mitrano gravatar imagePeter Mitrano ( 2016-01-13 20:18:47 -0500 )edit

You can start the simulation paused. Just provide it with the "-u" option.

maaft gravatar imagemaaft ( 2016-01-26 09:37:39 -0500 )edit
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Asked: 2016-01-08 23:02:42 -0500

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Last updated: Jan 09 '16