You're reading the documentation for an older, but still supported, version of ROS 2. For information on the latest version, please have a look at Iron.
Release Notes
This page should highlight the most important changes of the ros2_control framework in the humble release. If you are skipping a distribution update, make sure to read the release notes of all intermediate distributions.
These lists might not be complete, see the CHANGELOG.rst
files in the respective repositories for a full list of changes.
For necessary changes to your code for a version update, see the Migration Guides.