Problem Description
When using moveit setup assistant, I found that there is no description of chain in planning groups in the tutorial, but when looking at other configuration packages, I found that many of them are using chain.
understand
Therefore, the following understanding was obtained by consulting the data:
A serial chain is specified using the base link and the tip link. The tip link in a chain is the child link of the last joint in the chain. The base link in a chain is the parent link for the first joint in the chain.
That is, the chain is a Serial Chain (continuous chain), and the serial chain is specified by specifying the base link and tip link. The tip link is the child link in the last joint, and the base link is the parent link in the first joint.
use
Joints, Links, Chains and Subgroups represent different ways that you can use to specify which parts of the robot (as specified in the URDF) are part of your current planning group.
Looking at the srdf wiki, you can find some more information on the different types. For instance, notice that when a joint is added, the child link is automatically also included.
A chain is just an easy way to add several joints and links to the srdf without having to manually select all the joints/links in between. It is not advisable to mix different methods in a single group.
Hope that clears things up a bit.
This is a convenient way to add multiple joints and links to srdf without manually adding the required joints or links.