Navigation succeeds, but exploration hangs; return to initial pose ignored sometimes

[kaiaai]

Hello,
I have been playing with your code. Thank you for making it available. It works well in my simulation (living room type) except issue #3, but I have noticed three issues so far in the physical environment:

1. Navigation succeeds, then exploration hangs - even though there are (apparently) plenty of frontiers to explore
   
2. In the middle of, say, 6x6 meter room the code prints "no more frontiers" and stops, even though there is lots of frontiers remaining
3. Often return to the initial pose gets skipped. I've seen it work only once.

Any suggestions how to fix that are most welcome!
Thank you

[16holson]

I am having the same issue, have you been able to fix it?

[kaiaai]

So far no, I haven't had time to debug it.

[charlielito]

1. Hi! Could you share more details? Ros version?
2. Can you share a rosbag with that behavior so we can debug it?
3. When you say there are lots of frontiers remaining what do you mean? Visually, do you think there are still frontiers to explore?

[kaiaai]

Hi, I used ROS2 Humble.
Sorry, don't have a rosbag and I have moved on to other frontier exploration implementations.
If I remember well, yes, sometimes it leaves the job unfinished - plenty of frontiers left to explore.

[charlielito]

Could you share the other implementation?

[kaiaai]

1. https://github.com/kaiaai/auto_mapper (a cleaned-up fork of https://github.com/Omar-Salem/auto_mapper)
2. https://github.com/kaiaai/nav2_wfe (a fixed fork of https://github.com/SeanReg/nav2_wavefront_frontier_exploration)

Incidentally, that said these implementations still have practical problems.

• they don't take the robot footprint size into account. So, my bots keep trying to sneak into narrow bottlenecks.
• the frontier clusters are sorted by size, not by distance from the robot. That makes my bots behave "oddly" - go back and forth across the room again, again and again "unnecessarily" instead of exploring one side of the room fully first, then moving across.
• near bottleneck obstacles, exploration code tells the bot to move to the next frontier cluster - and that cluster can be just a few centimeters away. However, Nav2 goal checker returns "navigation succeeded" without making the robot move at all - because the robot is too close to the navigation target already (less than, say, the default 25cm Nav2 goal checker setting).