Controller Server¶

Source code on Github.

The Controller Server implements the server for handling the controller requests for the stack and host a map of plugin implementations. It will take in path and plugin names for controller, progress checker and goal checker to use and call the appropriate plugins.

Parameters¶

controller_frequency:

Type	Default
double	20.0

Description: Frequency to run controller (Hz).

controller_plugins:

Type	Default
vector<string>	[‘FollowPath’]

Description

List of mapped names for controller plugins for processing requests and parameters.

Note

Each plugin namespace defined in this list needs to have a plugin parameter defining the type of plugin to be loaded in the namespace.

Example:

controller_server:
  ros__parameters:
    controller_plugins: ["FollowPath"]
    FollowPath:
      plugin: "dwb_core::DWBLocalPlanner"

progress_checker_plugin:

Type	Default
string	‘progress_checker’

Description

Mapped name for progress checker plugin for checking progress made by robot.

Note

The plugin namespace defined needs to have a plugin parameter defining the type of plugin to be loaded in the namespace.

Example:

controller_server:
  ros__parameters:
    progress_checker_plugin: "progress_checker"
    progress_checker:
      plugin: "nav2_controller::SimpleProgressChecker"

goal_checker_plugin:

Type	Default
string	‘goal_checker’

Description

Mapped name for goal checker plugin for checking goal is reached.

Note

The plugin namespace defined needs to have a plugin parameter defining the type of plugin to be loaded in the namespace.

Example:

controller_server:
  ros__parameters:
    goal_checker_plugin: "goal_checker"
    goal_checker:
      plugin: "nav2_controller::SimpleGoalChecker"

min_x_velocity_threshold:

Type	Default
double	0.0001

Description: The controller server filters the velocity portion of the odometry messages received before sending them to the controller plugin. Odometry values below this threshold (in m/s) will be set to 0.0.

min_y_velocity_threshold:

Type	Default
double	0.0001

Description: The controller server filters the velocity portion of the odometry messages received before sending them to the controller plugin. Odometry values below this threshold (in m/s) will be set to 0.0. For non-holonomic robots

min_theta_velocity_threshold:

Type	Default
double	0.0001

Description: The controller server filters the velocity portion of the odometry messages received before sending them to the controller plugin. Odometry values below this threshold (in rad/s) will be set to 0.0.

Provided Plugins¶

The plugins listed below are inside the nav2_controller namespace.

Default Plugins¶

When the progress_checker_plugin, goal_checker_plugin or controller_plugins parameters are not overridden, the following default plugins are loaded:

Namespace Plugin

“progress_checker” “nav2_controller::SimpleProgressChecker”

“goal_checker” “nav2_controller::SimpleGoalChecker”

“FollowPath” “dwb_core::DWBLocalPlanner”

Example¶

controller_server:
  ros__parameters:
    use_sim_time: True
    controller_frequency: 20.0
    min_x_velocity_threshold: 0.001
    min_y_velocity_threshold: 0.5
    min_theta_velocity_threshold: 0.001
    progress_checker_plugin: "progress_checker"
    goal_checker_plugin: "goal_checker"
    controller_plugins: ["FollowPath"]
    progress_checker:
      plugin: "nav2_controller::SimpleProgressChecker"
      required_movement_radius: 0.5
      movement_time_allowance: 10.0
    goal_checker:
      plugin: "nav2_controller::SimpleGoalChecker"
      xy_goal_tolerance: 0.25
      yaw_goal_tolerance: 0.25
      stateful: True
    FollowPath:
      plugin: "dwb_core::DWBLocalPlanner"