0
$\begingroup$

the link origin and the corresponding collision, inertial, and visual origins

I understand that the collision, visual, and inertial origins are all starting from the link origin, but how do you change the link origin? I have a joint in the wrong place (relative to the child link) and cannot seem to move it.

Here is the image for it:

joint is not rotating around the right origin

It is supposed to rotate around the middle of the black servos sticking out of the cylinder.

Also is there a place for good urdf documentation? I have been struggling with it. Thank you!

$\endgroup$

1 Answer 1

0
$\begingroup$

I understand that the collision, visual, and inertial origins are all starting from the link origin

This is the default behaviour unless a pose is explicitly mentioned. Take a look at the following extract from the ROS Wiki:

   1  <link name="my_link">
   2    <inertial>
   3      <origin xyz="0 0 0.5" rpy="0 0 0"/>
   4      <mass value="1"/>
   5      <inertia ixx="100"  ixy="0"  ixz="0" iyy="100" iyz="0" izz="100" />
   6    </inertial>
   7 
   8    <visual>
   9      <origin xyz="0 0 0" rpy="0 0 0" />
  10      <geometry>
  11        <box size="1 1 1" />
  12      </geometry>
  13      <material name="Cyan">
  14        <color rgba="0 1.0 1.0 1.0"/>
  15      </material>
  16    </visual>
  17 
  18    <collision>
  19      <origin xyz="0 0 0" rpy="0 0 0"/>
  20      <geometry>
  21        <cylinder radius="1" length="0.5"/>
  22      </geometry>
  23    </collision>
  24  </link>

We can see here that we have the option to set the position and the orientation of the visual representation, the collision geometry, and the inertial information in the link element.

Afterwards, if you want to place the joint between two links in an offset, you have access to the <origin> tag in the joint as well.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.