Frames in SDF robot model: how to define relative links?
I just started writing an SDF model for a robot arm and I would like to define the pose of a link relative to another link, as opposed to the model frame. The SDF spec mentions both a frame tag (http://www.sdformat.org/spec?ver=1.5&...) and a frame attribute of the pose tag (http://www.sdformat.org/spec?ver=1.5&...), but I can't find any documentation or examples of how to properly use it.
Here's a simple example of what I'm trying to do that isn't working:
<?xml version="1.0"?>
<sdf version="1.6">
<model name="example">
<link name="base">
<pose>0 0 0 0 0 0</pose>
<visual name="visual">
<geometry>
<cylinder>
<radius>0.1</radius>
<length>0.025</length>
</cylinder>
</geometry>
</visual>
</link>
<link name="link1">
<pose>0 0 0.1 0 0 0</pose>
<visual name="visual">
<geometry>
<box>
<size>0.2 0.05 0.1</size>
</box>
</geometry>
</visual>
</link>
<link name="link2">
<!-- Want this to be relative to link1 -->
<pose frame="link1">0.2 0 0 0 0 0</pose>
<visual name="visual">
<geometry>
<box>
<size>0.2 0.05 0.1</size>
</box>
</geometry>
</visual>
</link>
</model>
</sdf>
However, this is the output (I'd like link2 to be at same z-height as link1):
Given that the frame information isn't exposed in the Gazebo Model Editor GUI, I suspect frame isn't completely supported?