Navigation Stack Configuration

Overview

This package configures the ROS 2 Navigation Stack needed to give any X-Series Interbotix LoCoBot platform the ability to perform simultaneous localization and mapping (SLAM), navigation, or just localization. It can be used with just the Intel RealSense D435 camera or with both the camera and the A2 RPLidar laser scanner. Localization and mapping is done using the rtabmap_ros or (in some distributions) the slam_toolbox ROS packages while navigation is accomplished via the Nav2 stack.

Note

For best results, this package should be run with the robot in an indoor, uncluttered environment that does not contain too much sunlight and has minimal reflective surfaces.

Usage

SLAM From Scratch

To get SLAM up and running using RTAB-Map, type the following in a terminal on the robot computer:

$ ros2 launch interbotix_xslocobot_nav xslocobot_rtabmap.launch.py robot_model:=locobot_wx200 use_lidar:=true slam_mode:=mapping rtabmap_args:=-d

Localization

Once you've finished mapping your desired environment, the next step is to have the robot uses its sensors to just localize itself within the map while navigating. To do so, type the following in a terminal on the robot computer:

$ ros2 launch interbotix_xslocobot_nav xslocobot_rtabmap.launch.py robot_model:=locobot_wx200 use_lidar:=true slam_mode:=localization

Troubleshooting

Time out waiting for transform...

When starting the Nav Stack (either when continuing a map or just doing localization) on your robot, you may see some warnings appear in the terminal. For example...

Timed out waiting for transform from locobot_wx200/base_footprint to map to become available before running costmap, tf error: canTransform: target_frame map does not exist.. canTransform returned after 0.100567 timeout was 0.1

The reason this appears is because no map is being supplied to the navigation stack. The reason for that is because it takes RTAB-Map a few seconds to generate the map from its database (which could be hundreds of megabytes). As such, this warning can be safely ignored assuming it stops once RTAB-Map gets the map out.

Rejected Loop Closure

When starting the Nav stack or during mapping, you may see the following warning appear (or similar) in the terminal...

Rtabmap.cpp:2533::process() Rejected loop closure 694 -> 773: Not enough inliers 0/20 (matches=0) between 694 and 772

Similar to the first warning, this can be ignored if it only shows up a few times at node startup. It just means that RTAB-Map has failed to determine where the robot is in the map. If you're mapping too quickly, this warning can also appear, so slow down a bit.

Robot does not go to same location after map reset

If using the Create® 3 base, the robot keeps its odometry through sessions and power cycles. You may need to use the /reset_pose service with each new map to ensure the robot goes to the same location.