  Developments in mobile robot navigation have enabled robots to operate in
warehouses, retail stores, and on sidewalks around pedestrians. Various
navigation solutions have been proposed, though few as widely adopted as ROS
Navigation. 10 years on, it is still one of the most popular navigation
solutions. Yet, ROS Navigation has failed to keep up with modern trends. We
propose the new navigation solution, Navigation2, which builds on the
successful legacy of ROS Navigation. Navigation2 uses a behavior tree for
navigator task orchestration and employs new methods designed for dynamic
environments applicable to a wider variety of modern sensors. It is built on
top of ROS2, a secure message passing framework suitable for safety critical
applications and program lifecycle management. We present experiments in a
campus setting utilizing Navigation2 to operate safely alongside students over
a marathon as an extension of the experiment proposed in Eppstein et al. The
Navigation2 system is freely available at
https://github.com/ros-planning/navigation2 with a rich community and
instructions.
