the Turtlebot3 (not compatible with explore_lite because it doesn't use move_base for commands)
This confuses me: according to turtlebot3_navigation move_base is definitely used.
Edit:
but when it's running the SLAM demo per virtual SLAM instructions here, and I then print the list of topics, move_base is not one of them.
move_base is not a topic. It's a node (edit: and an action server namespace).
It's using move_base_simple.
This also confuses me. Are we talking about the same package? See turtlebot3_navigation/launch/move_base.launch.
Is this the move_base_simple you refer to, or the topic based interface to move_base?
Edit 2:
I don't have time to look into the TB3 setup right now, but just to give you some pointers:
when I run other robots like the husky, there are topics like move_base/cmd_vel, and those don't show up with turtlebot3
the topic name cmd_vel is a choice, it could be called anything. The fact that many robot configurations have it as move_base/cmd_vel is just their preferred setup.
Looking at the launch file I linked earlier, it would appear that move_base will output Twists on /cmd_vel by default (here).
After your comment, I checked the node list and while running the simulation as described above, there is no move_base node either.
that would be something to check, if you're still interested in using the TB3. According to the launch file, move_base is definitely used, so the name should show up.
So I think that move_base is not actually used, unless you count move_base_simple, which shows up in the topic list but not the nodes.
Well, again: move_base_simple is not a node, it's a topic. You should probably use rostopic info /move_base_simple/goal to see who is subscribing or publishing to that.
Originally posted by gvdhoorn with karma: 86574 on 2019-03-11
This answer was ACCEPTED on the original site
Post score: 3
Original comments
Comment by kitkatme on 2019-03-11:
confuses me too, but when it's running the SLAM demo per virtual SLAM instructions here, and I then print the list of topics, move_base is not one of them. It's using move_base_simple. Maybe that still counts as move_base and that's why they list it, but explore_lite isn't set up for that. (It's worth trying to rewrite turtlebot3 to be compatible with explore_lite, but I figured I'd ask if there is anything already set up since I'm working on a deadline and very new to ROS.)
Comment by kitkatme on 2019-03-11:
ah, thanks for the clarification! to be more specific with the turtlebot3, when I run other robots like the husky, there are topics like move_base/cmd_vel, and those don't show up with turtlebot3. After your comment, I checked the node list and while running the simulation as described above, there is no move_base node either. Also explore_lite hangs in its initialization at the point where it's waiting to connect to move_base server. So I think that move_base is not actually used, unless you count move_base_simple, which shows up in the topic list but not the nodes.
Comment by kitkatme on 2019-03-11:
thanks for pointing me to that launch file!! problem solved! when I run move_base.launch in addition to the turtlebot3 SLAM and explore_lite packages, frontier exploration works.
Comment by gvdhoorn on 2019-03-11:
Now I'm really confused. Did you not follow the instructions in the Virtual Navigation with TurtleBot3 section of the manual that you linked to earlier?
Comment by kitkatme on 2019-03-11:
No; as mentioned, I followed the virtual SLAM instructions
Comment by gvdhoorn on 2019-03-11:
explore_lite is essentially just sending navigation goals to a running move_base instance/stack (replacing a human sending it goals in a sense). So you'd have to have the nav stack running, or it won't work.
