Robot fails in narrow corridors

1. Symptoms

• The planner finds no path through a door the robot physically fits.
• The robot stops or oscillates in a corridor.
• The robot clips the door frame.

2. Possible causes

• Inflation radius too large, making the passage look blocked.
• Footprint larger than the real robot, or a circular approximation of a long robot.
• A planner that assumes a circular robot.
• Localisation error comparable to the free margin.
• Controller speed or critic weights keep it away from walls.
• Costmap resolution too coarse.

3. Measurements to collect

• Passage width versus robot width and the costmap cell size.
• Inflation and footprint in the costmap visualisation.
• Localisation error at the passage.

4. Diagnostic commands

Commands are not executed by the site’s automated tests (they need a ROS 2 Jazzy installation or the robot).

ros2 param get /global_costmap/global_costmap inflation_layer.inflation_radius
ros2 topic echo /local_costmap/published_footprint --once
ros2 topic echo /global_costmap/costmap --once

5. Step-by-step investigation

1. Visualise the costmaps with the inflated areas at the passage.
2. Compare passage width with the robot width plus margin.
3. Check footprint and inflation against the real robot.
4. Check the planner assumptions (see the planner guide).
5. Check localisation error and goal tolerances.
6. Reduce speed in the passage.

6. Corrective actions

• Set the footprint to the true shape and reduce inflation where safe.
• Use a footprint-aware planner (state lattice) for non-circular robots.
• Improve localisation or add a marker at the doorway.
• Use higher costmap resolution near narrow places.

7. Validation after the fix

• The robot passes the narrowest passage ten times without contact.

References

• See the costmap guide and the planner guide.