Feature request

Feature description

I am interested in navigating to a dynamic point at a certain distance. Of course, I compromise to be working on this next weeks, but I would like to know your opinion about the best way to get it.

Using this feature, we could follow a person. Using Nav2 for following a person lets you avoid obstacles during the following.

Implementation considerations

• I am not very sure how to activate this behavior. Maybe extending bt_navigator to manage another action that activates this operation mode.
• The (dynamic) goal position could be received using a subscription to a topic of geometry_msgs/msg/Vector3Stamped
• It should use another behavior tree that would compute the path to the pose and would follow the path. If the distance is lower than a configured distance (it could be set when activating this mode) the robot stop translation and only rotates to the goal, if it changes.
• How to detect the object to follow and what to do if it is lost is out of the scope of this feature, as this situation will be managed by the application (moving to the last know position, for example).