Are Joint Lower and Upper Limits Required in SDF?

asked 2016-03-21 09:53:31 -0500

liangfok gravatar image

According to SDF v 1.6's joint limit syntax, a joint limit's <lower> and <upper> elements are required ("Required: 1") but its text description states "Omit if joint is continuous".

image description

Isn't this a contradiction? If the <lower> and <upper> elements can be omitted to support continuous joints, shouldn't the "Required: 1" be changed to "Required: 0"?

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While SDF is in use in some parts of ROS, we generally prefer it if you'd post questions like this on the Gazebo specific Answers site. I'm going to close this for now: if you don't agree, please re-open and tell us why you think it should be on this site.

gvdhoorn gravatar image gvdhoorn  ( 2016-03-21 11:01:07 -0500 )edit

I reopened the question because I do not believe this is a Gazebo-specific question. To my knowledge, SDF is not Gazebo-specific and many other processes in the ROS ecosystem like controller, planners, visualizers, etc., may use the models specified within the SDF file.

liangfok gravatar image liangfok  ( 2016-03-23 09:38:22 -0500 )edit

I'll leave this open, but SDF is actually not really used in ROS (at least not in the parts you mention). That is URDF. The whole SDF vs URDF issue is actually something that many people would like to see resolved.

gvdhoorn gravatar image gvdhoorn  ( 2016-03-23 09:48:10 -0500 )edit

Agreed. I thought (perhaps incorrectly) that URDF is deprecated and that SDF is its replacement, so my (perhaps wrong) assumption was the entire ROS ecosystem would eventually be upgraded to support SDF.

liangfok gravatar image liangfok  ( 2016-03-23 10:04:57 -0500 )edit

URDF is deprecated and that SDF is its replacement

That is something I hear more often, but is not really true. There was a robot description formats ng live meeting a few weeks back. Might be interesting.

gvdhoorn gravatar image gvdhoorn  ( 2016-03-23 10:39:06 -0500 )edit