ros2-nav2

The snap provides mapping, localization and navigation capabilities.

The ros2-nav2 snap is designed as a general package that offers navigation functionality for robots. To ensure maximum flexibility for users, it is intentionally provided without any preset configurations.

The ros2-nav2 snap must be configured by means of snap parameters. The available configuration parameters are listed below:

 - simulation (string, default: "False")
 - slam-config (string, default: "")
 - map-saver-config (string, default: "")
 - map-yaml-path (string, default: "")
 - map (string, default="${SNAP_COMMON}/maps/current_map.yaml")
 - localization-config (string, default: "")
 - navigation-config (string, default: "")

The slam-config, localization-config, and navigation-config parameters are essentials for the proper functioning of these applications.

These parameters must be set either to a local configuration file accessible within the SNAP environment (such as $SNAP_COMMON), or to a URL hosting the desired configuration.

Additionally, a set of configuration_templates is available at $SNAP_COMMON/configuration_templates. Those files are only meant to be a template, they can be modified and used by setting them to the parameters. An example of using a template for slam-config is as follows:

snap set ros2-nav2 slam-config="/var/snap/ros2-nav2/common/configuration_templates/slam_params_template.yaml"

In case you want to reinitialize the templates, you can simply issue the following command: ros2-nav2.reset-config-templates

As mentioned, those parameters can also be can also be configured with a URL as follows:

 snap set ros2-nav2 <app-name>-config="https://raw.githubusercontent.com/robot-repo/<app-name>_params.yaml"

Note: the URL must be reachable by the snap. When using a URL, the configuration file will be downloaded everytime the app is launched. Therefore a configuration update upstream will be applied with the application relaunch.

The mapping application can be launched as,

 snap start ros2-nav2.slam

After launching the app, simply drive the robot around until you've mapped the area. Once finished, stop the mapping with,

 snap stop ros2-nav2.slam

This will terminate the mapping and automatically save the map in '${SNAP_COMMON}/maps/new_map.{yaml,png}'.

If mapping is not required, a map can also be loaded via the map-yaml-path parameter. The parameter can either be set to a local file with:

 snap set ros2-nav2 map-yaml-path="$SNAP_COMMON/maps/map.yaml"

Or by means of a URL with:

 snap set ros2-nav2 map-yaml-path="https://raw.githubusercontent.com/robot-repo/map.yaml"

The image associated to the map is automatically extracted from the yaml file.

With the environment mapped, one can make use of the autonomous navigation. To do so, start the localisation and navigation with:

 snap start ros2-nav2.localization
 snap start ros2-nav2.navigation

Those application can be then stopped with:

 snap stop ros2-nav2.localization
 snap stop ros2-nav2.navigation