Mapping with SLAM Toolbox and EasyNav

This HowTo explains how to create a 2D occupancy map using SLAM Toolbox and store it for later use with the Simple Stack in EasyNavigation (EasyNav).

Overview 

This tutorial uses the Turtlebot2 (Kobuki) simulator from the easynav_playground_kobuki repository and the Simple Stack, which relies on binary occupancy grids (0 for free, 1 for occupied).

The workflow consists of:

Running the simulator.
Starting SLAM Toolbox to build the map.
Using EasyNav to receive and save the map through the Simple Maps Manager.
Saving the generated YAML + image files for later use.

—

Setup 

Before starting, ensure you have completed Build & Install and cloned the following repositories in your workspace:

EasyNavigation
easynav_plugins
easynav_playground_kobuki (for simulation)
easynav_indoor_testcase (for configuration and maps)

All packages should build correctly with:

cd ~/easynav_ws
colcon build --symlink-install
source install/setup.bash

—

Running SLAM Toolbox 

SLAM Toolbox is part of the Nav2 ecosystem and can be installed via apt:

sudo apt install ros-${ROS_DISTRO}-slam-toolbox

Alternatively, it can be built from source: https://github.com/SteveMacenski/slam_toolbox

SLAM Toolbox publishes a nav_msgs/msg/OccupancyGrid on the /map topic. EasyNav’s Simple Maps Manager listens on:

/maps_manager_node/simple/incoming_map

and can consume this topic directly.

—

Step-by-Step Instructions 

Launch the simulator (with or without GUI)

ros2 launch easynav_playground_kobuki playground_kobuki.launch.py gui:=false

Open RViz2
```
ros2 run rviz2 rviz2 --ros-args -p use_sim_time:=true
```
Note

The /map topic and map frame will only appear after launching SLAM Toolbox.
Launch SLAM Toolbox

SLAM Toolbox expects a topic named /scan. In this setup, the Kobuki’s LIDAR publishes on /scan_raw, so you must remap it.

Edit or copy the launcher file from:
```
/opt/ros/${ROS_DISTRO}/share/slam_toolbox/launch/online_async_launch.py
```
Add the following remapping:
```
remappings=[
    ('/scan', '/scan_raw'),
],
```
Then launch SLAM Toolbox:
```
ros2 launch slam_toolbox online_async_launch.py
```
Teleoperate the robot to build the map
```
ros2 run teleop_twist_keyboard teleop_twist_keyboard
```
As you move the robot, SLAM Toolbox will publish the growing map on /map, visible in RViz2.

—

Using EasyNav to Receive and Save the Map 

Next, run EasyNav in mapping mode, where only the Maps Manager is active and the rest of the nodes use dummy plugins.

Example configuration (simple.mapping.params.yaml):

controller_node:
  ros__parameters:
    use_sim_time: true
    controller_types: [dummy]
    dummy:
      plugin: easynav_controller/DummyController

localizer_node:
  ros__parameters:
    use_sim_time: true
    localizer_types: [dummy]
    dummy:
      plugin: easynav_localizer/DummyLocalizer

maps_manager_node:
  ros__parameters:
    use_sim_time: true
    map_types: [simple]
    simple:
      freq: 10.0
      plugin: easynav_simple_maps_manager/SimpleMapsManager

planner_node:
  ros__parameters:
    use_sim_time: true
    planner_types: [dummy]
    dummy:
      plugin: easynav_planner/DummyPlanner

sensors_node:
  ros__parameters:
    use_sim_time: true
    forget_time: 0.5

system_node:
  ros__parameters:
    use_sim_time: true
    position_tolerance: 0.1
    angle_tolerance: 0.05

Launch EasyNav and remap the incoming map topic:

ros2 run easynav_system system_main --ros-args \
  --params-file ~/easynav_ws/src/easynav_indoor_testcase/robots_params/simple.mapping.params.yaml \
  -r /maps_manager_node/simple/incoming_map:=/map

At this point, the Simple Maps Manager receives the map directly from SLAM Toolbox.

—

Saving and Reusing the Map 

Save the generated map
```
ros2 service call /maps_manager_node/simple/savemap std_srvs/srv/Trigger
```
By default, the map is stored under /tmp/default.yaml and /tmp/default.pgm.

Rename and move the map for later use

mv /tmp/default.yaml ~/easynav_ws/src/easynav_indoor_testcase/maps/house.yaml
mv /tmp/default.pgm  ~/easynav_ws/src/easynav_indoor_testcase/maps/house.pgm

Update your navigation parameters

Modify the map section in your configuration file as follows:

maps_manager_node:
  ros__parameters:
    use_sim_time: true
    map_types: [simple]
    simple:
      freq: 10.0
      plugin: easynav_simple_maps_manager/SimpleMapsManager
      package: easynav_indoor_testcase
      map_path_file: maps/house.yaml

You can now reuse this map for any Simple Stack navigation tutorial (see Navigating with SimpleStack and EasyNav).

—

Notes 

The saved format (YAML + PGM) is fully compatible with MoveBase, Nav2, and other ROS 2 mapping systems.
To perform navigation with graded cost values instead of binary occupancy, use the Costmap Stack (Mapping with the Costmap Stack).
You can visualize both SLAM and EasyNav map topics in RViz2 to confirm synchronization.

Mapping with SLAM Toolbox and EasyNav

Overview

Setup

Running SLAM Toolbox

Step-by-Step Instructions

Using EasyNav to Receive and Save the Map

Saving and Reusing the Map

Notes