configuring-controller-server.rst

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. It also hosts the local costmap.

Parameters

controller_frequency:	Type Default double 20.0 Description Frequency to run controller (Hz).
costmap_update_timeout:	Type Default double 0.3 Description The timeout value (seconds) for the costmap to be fully updated before a control effort can be computed.
use_realtime_priority:	Type Default bool false Description Adds soft real-time prioritization to the controller server to better ensure resources to time sensitive portions of the codebase. This will set the controller's execution thread to a higher priority than the rest of the system (90) to meet scheduling deadlines to have less missed loop rates. To use this feature, you use set the following inside of /etc/security/limits.conf to give userspace access to elevated prioritization permissions: <username> soft rtprio 99 <username> hard rtprio 99
publish_zero_velocity:	Type Default bool true Description Whether to publish a zero velocity command on goal exit. This is useful for stopping the robot when a goal terminates.
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_plugins:	Type Default vector<string> ["progress_checker"] Description Mapped name for progress checker plugin for checking progress made by robot. Formerly progress_checker_plugin for Humble and older with a single string plugin. 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_plugins: ["progress_checker"] # progress_checker_plugin: "progress_checker" For Humble and older progress_checker: plugin: "nav2_controller::SimpleProgressChecker"
goal_checker_plugins:	Type Default vector<string> ["goal_checker"] Description Mapped name for goal checker plugin for checking goal is reached. When the number of the plugins is more than 2, each FollowPath action needs to specify the goal checker plugin name with its goal_checker_id field. 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_plugins: ["goal_checker"] goal_checker: plugin: "nav2_controller::SimpleGoalChecker"
path_handler_plugins:	Type Default vector<string> ["PathHandler"] Description Mapped name for path handler plugin for processing path from the planner. When the number of the plugins is more than 2, each FollowPath action needs to specify the path handler plugin name with its path_handler_id field. 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: path_handler_plugins: ["PathHandler"] path_handler: plugin: "nav2_controller::FeasiblePathHandler"
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.
failure_tolerance:	Type Default double 0.0 Description The maximum duration in seconds the called controller plugin can fail (i.e. the computeVelocityCommands function of the plugin throwing an exception) before the nav2_msgs::action::FollowPath action fails. Setting it to the special value of -1.0 makes it infinite, 0 to disable, and any positive value for the appropriate timeout.
speed_limit_topic:	Type Default string "speed_limit" Description Speed limiting topic name to subscribe. This could be published by Speed Filter (please refer to :ref:`speed_filter` configuration page). You can also use this without the Speed Filter as well if you provide an external server to publish these messages.
odom_topic:	Type Default string "odom" Description Topic to get instantaneous measurement of speed from.
odom_duration:	Type Default double 0.3 Description Time (s) to buffer odometry commands to estimate the robot speed.
enable_stamped_cmd_vel:	Type Default bool true Description Whether to use geometry_msgs::msg::Twist or geometry_msgs::msg::TwistStamped velocity data. True uses TwistStamped, false uses Twist. Note: This parameter is default false in Jazzy or older! Kilted or newer uses TwistStamped by default.
bond_heartbeat_period:	Type Default double 0.25 Description The lifecycle node bond mechanism publishing period (on the /bond topic). Disabled if inferior or equal to 0.0.
introspection_mode:	Type Default string "disabled" Description The introspection mode for services and actions. Options are "disabled", "metadata", "contents".
allow_parameter_qos_overrides:	Type Default bool true Description Whether to allow QoS profiles to be overwritten with parameterized values.
search_window:	Type Default double 2.0 Description How far (in meters) along the path the searching algorithm will look for the closest point.

Provided Plugins

The plugins listed below are inside the nav2_controller namespace.

.. toctree::
  :maxdepth: 1

  nav2_controller-plugins/simple_progress_checker.rst
  nav2_controller-plugins/pose_progress_checker.rst
  nav2_controller-plugins/axis_goal_checker.rst
  nav2_controller-plugins/simple_goal_checker.rst
  nav2_controller-plugins/stopped_goal_checker.rst
  nav2_controller-plugins/position_goal_checker.rst
  nav2_controller-plugins/feasible_path_handler.rst

Default Plugins

When the progress_checker_plugins, goal_checker_plugin, path_handler_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"
"path_handler"	"nav2_controller::FeasiblePathHandler"
"FollowPath"	"dwb_core::DWBLocalPlanner"

Example

controller_server:
  ros__parameters:
    controller_frequency: 20.0
    costmap_update_timeout: 0.3
    min_x_velocity_threshold: 0.001
    min_y_velocity_threshold: 0.5
    min_theta_velocity_threshold: 0.001
    failure_tolerance: 0.3
    odom_topic: "odom"
    odom_duration: 0.3
    progress_checker_plugins: ["progress_checker"] # progress_checker_plugin: "progress_checker" For Humble and older
    goal_checker_plugins: ["goal_checker"] # goal_checker_plugin: "goal_checker" For Galactic and older
    path_handler_plguins: ["PathHandler"]
    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
      path_length_tolerance: 1.0
      stateful: True
    PathHandler:
      plugin: "nav2_controller::FeasiblePathHandler"
      prune_distance: 2.0
      enforce_path_inversion: True
      enforce_path_rotation: False
      inversion_xy_tolerance: 0.2
      inversion_yaw_tolerance: 0.4
      minimum_rotation_angle: 0.785
      reject_unit_path: False
    FollowPath:
      plugin: "dwb_core::DWBLocalPlanner"