How to use planner selector and controller selector actions?

[rajeshAnt]

• Operating System:
  • Ubuntu 22.04.4
• ROS2 Version:
  • Humble
• DDS implementation:
  • CycloneDDS

Hi, i am new to the nav2 architecture and I am trying to use different planners at different stages of my robot navigation.

bt_navigator and planner_server parms from my nav_params.yaml file looks like this.

bt_navigator:
  ros__parameters:
    global_frame: map
    robot_base_frame: base_link
    odom_topic: /odometry/filtered
    bt_loop_duration: 10
    default_server_timeout: 20
    navigators: ["navigate_to_pose", "navigate_through_poses"]
    navigate_to_pose:
      plugin: "nav2_bt_navigator::NavigateToPoseNavigator"
    navigate_through_poses:
      plugin: "nav2_bt_navigator::NavigateThroughPosesNavigator"
    default_bt_xml: "my_path/config/navigate_to_pose_w_replanning_and_recovery.xml"
    # 'default_nav_through_poses_bt_xml' and 'default_nav_to_pose_bt_xml' are use defaults:
    # nav2_bt_navigator/navigate_to_pose_w_replanning_and_recovery.xml
    # nav2_bt_navigator/navigate_through_poses_w_replanning_and_recovery.xml
    # They can be set here or via a RewrittenYaml remap from a parent launch file to Nav2.

    # plugin_lib_names is used to add custom BT plugins to the executor (vector of strings).
    # Built-in plugins are added automatically
    plugin_lib_names:
    - nav2_compute_path_to_pose_action_bt_node
    - nav2_compute_path_through_poses_action_bt_node
    - nav2_follow_path_action_bt_node
    - nav2_back_up_action_bt_node
    - nav2_spin_action_bt_node
    - nav2_wait_action_bt_node
    - nav2_clear_costmap_service_bt_node
    - nav2_is_stuck_condition_bt_node
    - nav2_goal_reached_condition_bt_node
    - nav2_goal_updated_condition_bt_node
    - nav2_initial_pose_received_condition_bt_node
    - nav2_reinitialize_global_localization_service_bt_node
    - nav2_rate_controller_bt_node
    - nav2_distance_controller_bt_node
    - nav2_speed_controller_bt_node
    - nav2_truncate_path_action_bt_node
    - nav2_goal_updater_node_bt_node
    - nav2_recovery_node_bt_node
    - nav2_pipeline_sequence_bt_node
    - nav2_round_robin_node_bt_node
    - nav2_transform_available_condition_bt_node
    - nav2_time_expired_condition_bt_node
    - nav2_distance_traveled_condition_bt_node
    - nav2_single_trigger_bt_node
    - nav2_goal_updated_controller_bt_node
    - nav2_is_battery_low_condition_bt_node
    - nav2_navigate_through_poses_action_bt_node
    - nav2_navigate_to_pose_action_bt_node
    - nav2_remove_passed_goals_action_bt_node
    - nav2_planner_selector_bt_node
    - nav2_controller_selector_bt_node
    - nav2_goal_checker_selector_bt_node

    error_code_names:
      - compute_path_error_code
      - follow_path_error_code

bt_navigator_rclcpp_node:
  ros__parameters:
    use_sim_time: False

planner_server:
  ros__parameters:
    expected_planner_frequency: 10.0
    use_sim_time: False
    planner_plugins: ["GridBased_navfn", "GridBased_smac"]
    GridBased_navfn:
      plugin: "nav2_navfn_planner/NavfnPlanner"
    GridBased_smac:
      plugin: "nav2_smac_planner/SmacPlannerHybrid"

The navigate_to_pose_w_replanning_and_recovery.xml is

<!--
  This Behavior Tree replans the global path periodically at 1 Hz and it also has
  recovery actions specific to planning / control as well as general system issues.
  This will be continuous if a kinematically valid planner is selected.
-->
<root BTCPP_format="4" main_tree_to_execute="MainTree">
  <BehaviorTree ID="MainTree">
    <RecoveryNode number_of_retries="6" name="NavigateRecovery">
      <PipelineSequence name="NavigateWithReplanning">
        <ControllerSelector selected_controller="{selected_controller}" default_controller="FollowPath_DWB" topic_name="controller_selector"/>
        <PlannerSelector selected_planner="{selected_planner}" default_planner="GridBased_navfn" topic_name="planner_selector"/>
        <RateController hz="1.0">
          <RecoveryNode number_of_retries="1" name="ComputePathToPose">
            <ComputePathToPose goal="{goal}" path="{path}" planner_id="{selected_planner}" error_code_id="{compute_path_error_code}"/>
            <Sequence>
              <WouldAPlannerRecoveryHelp error_code="{compute_path_error_code}"/>
              <ClearEntireCostmap name="ClearGlobalCostmap-Context" service_name="global_costmap/clear_entirely_global_costmap"/>
            </Sequence>
          </RecoveryNode>
        </RateController>
        <RecoveryNode number_of_retries="1" name="FollowPath">
          <FollowPath path="{path}" controller_id="{selected_controller}" error_code_id="{follow_path_error_code}"/>
          <Sequence>
            <WouldAControllerRecoveryHelp error_code="{follow_path_error_code}"/>
            <ClearEntireCostmap name="ClearLocalCostmap-Context" service_name="local_costmap/clear_entirely_local_costmap"/>
          </Sequence>
        </RecoveryNode>
      </PipelineSequence>
      <Sequence>
        <Fallback>
          <WouldAControllerRecoveryHelp error_code="{follow_path_error_code}"/>
          <WouldAPlannerRecoveryHelp error_code="{compute_path_error_code}"/>
        </Fallback>
        <ReactiveFallback name="RecoveryFallback">
          <GoalUpdated/>
          <RoundRobin name="RecoveryActions">
            <Sequence name="ClearingActions">
              <ClearEntireCostmap name="ClearLocalCostmap-Subtree" service_name="local_costmap/clear_entirely_local_costmap"/>
              <ClearEntireCostmap name="ClearGlobalCostmap-Subtree" service_name="global_costmap/clear_entirely_global_costmap"/>
            </Sequence>
            <Spin spin_dist="1.57" error_code_id="{spin_error_code}"/>
            <Wait wait_duration="5.0"/>
            <BackUp backup_dist="0.30" backup_speed="0.15" error_code_id="{backup_code_id}"/>
          </RoundRobin>
        </ReactiveFallback>
      </Sequence>
    </RecoveryNode>
  </BehaviorTree>
</root>

I couldn't see the planner_selector topic when I do ros2 topic list. Is there any steps that i am missing in configuring the planner selector. Thanks in advance :)

[SteveMacenski]

Sometimes transient local QoS topics don't appear off hand in the CLI (nothing we can do about that in Nav2), but I'm sure if you did a ros2 topic info on it you'd see it. Try publishing to it and I think you'll see it works fine - we have unit tests for this so I know it works :-) Just make sure to use the right QoS settings

[rajeshAnt]

Hi, thanks for your reply. I was able to make the planner selector work but I had to do the following changes. I had to replace the parameter name to default_nav_to_pose_bt_xml and not the default_bt_xml: "my_path/config/navigate_to_pose_w_replanning_and_recovery.xml". And I used the behavior tree from the Humble branch as the base and added the planner and controller selector actions.