Behavior Server

Source code on Github.

The Behavior Server implements the server for handling various behavior, such as recoveries and docking, requests and hosting a vector of plugins implementing various C++ behaviors. It is also possible to implement independent behavior servers for each custom behavior, but this server will allow multiple behaviors to share resources such as costmaps and TF buffers to lower incremental costs for new behaviors.

Note: the wait recovery behavior has no parameters, the duration to wait is given in the action request. Note: pre-Rolling/Humble this was the Recovery server, not behavior server. Launch files, behaviors and tests were all renamed.

Behavior Server Parameters

local_costmap_topic

Type

Default

string

“local_costmap/costmap_raw”

Description

Raw costmap topic for collision checking on the local costmap.

global_costmap_topic

Type

Default

string

“global_costmap/costmap_raw”

Description

Raw costmap topic for collision checking on the global costmap.

local_footprint_topic

Type

Default

string

“local_costmap/published_footprint”

Description

Topic for footprint in the local costmap frame.

global_footprint_topic

Type

Default

string

“global_costmap/published_footprint”

Description

Topic for footprint in the global costmap frame.

cycle_frequency

Type

Default

double

10.0

Description

Frequency to run behavior plugins.

action_server_result_timeout

Type

Default

Unit

double

10.0

seconds

Description

The timeout value (in seconds) for action servers to discard a goal handle if a result has not been produced. This used to default to 15 minutes in rcl but was changed to 10 seconds in this PR #1012, which may be less than some actions in Nav2 take to run. For most applications, this should not need to be adjusted as long as the actions within the server do not exceed this deadline. This issue has been raised with OSRF to find another solution to avoid active goal timeouts for bookkeeping, so this is a semi-temporary workaround

transform_tolerance

Type

Default

double

0.1

Description

TF transform tolerance.

local_frame

Type

Default

string

“odom”

Description

Local reference frame.

global_frame

Type

Default

string

“map”

Description

Global reference frame.

robot_base_frame

Type

Default

string

“base_link”

Description

Robot base frame.

behavior_plugins

Type

Default

vector<string>

{“spin”, “back_up”, “drive_on_heading”, “wait”}

Description

List of plugin names to use, also matches action server names.

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:

behavior_server:
  ros__parameters:
    behavior_plugins: ["spin", "backup", "drive_on_heading", "wait"]
    spin:
      plugin: "nav2_behaviors/Spin"
    backup:
      plugin: "nav2_behaviors/BackUp"
    drive_on_heading:
      plugin: "nav2_behaviors/DriveOnHeading"
    wait:
      plugin: "nav2_behaviors/Wait"

Default Plugins

When the behavior_plugins parameter is not overridden, the following default plugins are loaded:

Namespace

Plugin

“spin”

“nav2_behaviors/Spin”

“backup”

“nav2_behaviors/BackUp”

“drive_on_heading”

“nav2_behaviors/DriveOnHeading”

“wait”

“nav2_behaviors/Wait”

Spin Behavior Parameters

Spin distance is given from the action request

simulate_ahead_time

Type

Default

double

2.0

Description

Time to look ahead for collisions (s).

max_rotational_vel

Type

Default

double

1.0

Description

Maximum rotational velocity (rad/s).

min_rotational_vel

Type

Default

double

0.4

Description

Minimum rotational velocity (rad/s).

rotational_acc_lim

Type

Default

double

3.2

Description

maximum rotational acceleration (rad/s^2).

enable_stamped_cmd_vel

Type

Default

bool

false

Description

Whether to use geometry_msgs::msg::Twist or geometry_msgs::msg::TwistStamped velocity data. True uses TwistStamped, false uses Twist.

BackUp Behavior Parameters

Backup distance, speed and time_allowance is given from the action request.

simulate_ahead_time

Type

Default

double

2.0

Description

Time to look ahead for collisions (s).

enable_stamped_cmd_vel

Type

Default

bool

false

Description

Whether to use geometry_msgs::msg::Twist or geometry_msgs::msg::TwistStamped velocity data. True uses TwistStamped, false uses Twist.

DriveOnHeading Behavior Parameters

DriveOnHeading distance, speed and time_allowance is given from the action request.

simulate_ahead_time

Type

Default

double

2.0

Description

Time to look ahead for collisions (s).

enable_stamped_cmd_vel

Type

Default

bool

false

Description

Whether to use geometry_msgs::msg::Twist or geometry_msgs::msg::TwistStamped velocity data. True uses TwistStamped, false uses Twist.

AssistedTeleop Behavior Parameters

AssistedTeleop time_allowance is given in the action request

projection_time

Type

Default

double

1.0

Description

Time to look ahead for collisions (s).

simulation_time_step

Type

Default

double

0.1

Description

Time step for projections (s).

cmd_vel_teleop

Type

Default

string

cmd_vel_teleop

Description

Topic to listen for teleop messages.

enable_stamped_cmd_vel

Type

Default

bool

false

Description

Whether to use geometry_msgs::msg::Twist or geometry_msgs::msg::TwistStamped velocity data. True uses TwistStamped, false uses Twist.

Example

behavior_server:
  ros__parameters:
    local_costmap_topic: local_costmap/costmap_raw
    local_footprint_topic: local_costmap/published_footprint
    global_costmap_topic: global_costmap/costmap_raw
    global_footprint_topic: global_costmap/published_footprint
    cycle_frequency: 10.0
    behavior_plugins: ["spin", "backup", "drive_on_heading", "wait", "assisted_teleop"]
    spin:
      plugin: "nav2_behaviors/Spin"
    backup:
      plugin: "nav2_behaviors/BackUp"
    drive_on_heading:
      plugin: "nav2_behaviors/DriveOnHeading"
    wait:
      plugin: "nav2_behaviors/Wait"
    assisted_teleop:
      plugin: "nav2_behaviors/AssistedTeleop"
    local_frame: odom
    global_frame: map
    robot_base_frame: base_link
    transform_timeout: 0.1
    simulate_ahead_time: 2.0
    max_rotational_vel: 1.0
    min_rotational_vel: 0.4
    rotational_acc_lim: 3.2
    enable_stamped_cmd_vel: false