Hands-On ROS for Robotics Programming

Caster

The caster description is nested inside the <link name="base_link"> element. This means that it's a rigid part that's fixed to the robot body. Let's go over what it is:

• It's a sphere that has a radius of 0.05 m, located at x=0.2 m, z=-0.125 m. Be aware that the Z coordinate is half of the box height (=0.25 m) and negative. This means that the top semi-sphere is embedded within the box and only the other semi-sphere stays visible on the bottom part of the box.
• By default, the same color is selected as what was defined for the box.

Inspect the following code carefully to ensure you understand it:

    <!-- Caster --> <visual name="caster"> <origin xyz="0.2 0 -0.125" rpy="0 0 0" /> <geometry> <sphere radius="0.05" /> </geometry> </visual> ...