[MSA] a brief description of the moveit Configuration Assistant chain in planning groups

Problem description

In the use of moveit setup assistant when , I found that there is nothing about planning groups in chain Description of , But when looking at other configuration packages , I found that many of them are in use chain.

understand

therefore , The following understanding can be obtained by consulting the materials ：

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.

namely ,chain It's a Serial Chain（ Continuous chain ）, By designation base link and tip link To specify the serial chain.tip link yes last joint Medium child link, base link yes first joint Medium parent link .

purpose

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 to add multiple joints and links To srdf A convenient way , There is no need to manually add the required joints or links.