Lyrical to M-Turtle

Migration Actions and Deprecations

Behavior Server plugin parameters are now namespaced

The behavior plugins' parameters are now declared under the plugin's name from behavior_plugins, in the same way the acceleration_limit, deceleration_limit and minimum_speed parameters of BackUp and DriveOnHeading already were. The old node-level names are no longer read, so existing configurations must be updated or the defaults will silently apply:

Old (node-level)	New (per plugin)
simulate_ahead_time	spin.simulate_ahead_time, backup.simulate_ahead_time, drive_on_heading.simulate_ahead_time
max_rotational_vel	spin.max_rotational_vel
min_rotational_vel	spin.min_rotational_vel
rotational_acc_lim	spin.rotational_acc_lim
projection_time	assisted_teleop.projection_time
simulation_time_step	assisted_teleop.simulation_time_step
cmd_vel_teleop	assisted_teleop.cmd_vel_teleop

Substitute your own plugin names if they differ from the defaults. Simply move the parameter under the plugin's declaration in your configuration.

Single Lifecycle Manager in Nav2 Bringup

PR #6410 combines the separate lifecycle managers for localization, navigation, SLAM, keepout zones, speed zones and the loopback simulator into a single lifecycle_manager_nav2, started by bringup_launch.py. Measured on the Turtlebot 4 simulation launch, which previously ran four lifecycle managers, this reduces Nav2's CPU use by around 25%. The nested launch files in nav2_bringup no longer start a lifecycle manager of their own. Each has a get_lifecycle_nodes(context) function that returns its lifecycle node names, which bringup_launch.py collects into the node_names of the single manager.

Launching a nested file by itself, such as ros2 launch nav2_bringup navigation_launch.py, now leaves the servers unconfigured. Launch bringup_launch.py instead and use its arguments to turn off what you do not need, for example use_localization:=False when SLAM or another source provides the map and the map to odom transform. Anything that used the old manager names, such as lifecycle_manager_navigation/manage_nodes, should use lifecycle_manager_nav2 instead; the Nav2 RViz panel is already updated.

Move your own nested launch files to the same pattern: remove the lifecycle manager from each one, add a get_lifecycle_nodes(context) function that returns its lifecycle node names, and build the node_names of your single manager from those functions plus your own nodes. The task server tutorial shows this.

If you would rather run a launch file on its own, start a lifecycle manager beside it.

Default BT Updates

Backup recovery now waits for the robot to move

PR #6635 replaces BackUp with the BackupWithReset subtree in six bundled navigation behavior trees with recovery actions. After a successful backup, the subtree skips another backup near the same pose. It allows backup again once the robot has moved at least reset_distance from the last backup pose. The backup history resets when the behavior tree is reloaded.

The updated trees also set wrap_around="true" on their RecoveryActions RoundRobin node so the recovery sequence can cycle (and for example spin can be executed multiple times). If you maintain a copy of one of these trees and want the same behavior, replace its recovery BackUp node with the BackupWithReset subtree and set wrap_around="true" on the RoundRobin. Adjust the frame names and reset distance for your robot.

Changes in FollowObject Action

FollowObject.action error codes are changed as below. If you are using this action you will have to adapt to handle new error codes:

Old	New
TF_ERROR = 901	TF_ERROR = 801
FAILED_TO_DETECT_OBJECT = 902	FAILED_TO_DETECT_OBJECT = 802
FAILED_TO_CONTROL = 903	FAILED_TO_CONTROL = 803
TIMEOUT = 904	TIMEOUT = 804
UNKNOWN = 999	UNKNOWN = 899

New Features and Improvements

Static Layer Overlays Without Resizing the Master

PR #6488 adds the Static Layer parameter resize_master, which defaults to true. Existing configurations require no changes: a Static Layer still resizes a non-rolling master costmap to match its incoming map.

Set resize_master: false for additional Static Layers whose maps should not control the master's geometry. For example, a Vector Object Server can publish an obstacle map with a smaller or changing extent while the primary Static Layer continues to own the site map geometry.

Assisted Teleop Times Out on Stale Teleop Commands

The AssistedTeleop behavior now stops the robot and fails the action with the new TELEOP_INPUT_TIMEOUT error code (733) when no teleop command has been received within the new teleop_command_timeout parameter (default 0.25 s).

Include Specific rclcpp Headers

PR #6558 replaces the broad rclcpp/rclcpp.hpp includes throughout Nav2 with the specific headers each file needs to speed up compilation and reduce build memory usage. We now recommend including specific rclcpp headers instead of globally including rclcpp/rclcpp.hpp.

See the ROS 2 documentation note on the rclcpp convenience header for more details.

MPPI Critics for Omnidirectional Velocity Limits

PR #6498 adds two MPPI critics. The ConstraintCritic bounds vx and vy separately. This creates a rectangular velocity space, with maximum translational velocity being sqrt(vx_max² + vy_max²). Therefore, any critic rewarding speed on an omnidirectional platform will lead to the robot driving diagonally, as sqrt(vx_max² + vy_max²) is larger than vx_max and vy_max alone.

• The OmniConstraintCritic (mppi::critics::OmniConstraintCritic) is intended to be used for omnidirectional models instead of the ConstraintCritic. Its velocity space is an ellipse spanned by the controller's vx_max, vx_min and vy_max, so it keeps the same functionality as the ConstraintCritic, while preventing speed rewarding critics from forcing the robot to drive diagonally.
• The MecanumCritic (mppi::critics::MecanumCritic) is intended to be used to constrain a mecanum robot's drivetrain to its reachable velocity. This, because a mecanum model's velocities vx, vy and wz are not independent from each other. Driving with vx_max is only possible when vy and wz are zero, as otherwise a wheel would saturate.

Neither critic is enabled by default; existing configurations are unaffected.