README

as2_behavior_tree

This module is used to implement a ROS2 node that executes navigation Behavior Trees for navigation of drone systems. The behavior_trees module uses the Behavior-Tree.CPP library for the core Behavior Tree processing.

The behavior_trees module provides navigation-specific behavior tree nodes and a ROS2 node implementation and launchers. It uses nav2_behavior_tree C++ template class for easily integrating ROS2 actions and services into Behavior Trees,

Index

• Installation

• AeroStack2 BT Nodes

  • Action

  • Condition

  • Control

  • Decorator

• How to create new nodes?

Installation

Dependencies:

sudo apt-get install ros-$ROS_DISTRO-behaviortree-cpp-v3
sudo apt-get install ros-$ROS_DISTRO-nav2-msgs
sudo apt-get install ros-$ROS_DISTRO-nav2-behavior-tree

You may also want to install Groot to build your own trees.

AeroStack2 BT Nodes

AeroStack2 offers a pull of predefined behavior nodes to build your own Behavior Tree.

Action

Show Actions

Arm

Arms the drone. Input port is not intended to use by the user, but used because nav2_behavior_tree service action node implementation.

Returns SUCCESS if service result is true. Otherwise, returns FAILURE.

Port	In / Out	Description
service_name	In	Service name which will be called.

Disarm

Disarms the drone. Input port is not intended to use by the user, but used because nav2_behavior_tree service action node implementation.

Returns SUCCESS if service result is true. Otherwise, returns FAILURE.

Port	In / Out	Description
service_name	In	Service name which will be called.

Echo

Prints data getted by input port. Used for debugging purpouses.

Always returns SUCCESS after echoing.

Port	In / Out	Description
data	In	String to be echoed.

FollowPath

TBD

GoTo

Go to specified position with given maximum speed and yaw.

Returns SUCCESS if action finishes successfully or cancelled. Returns FAILURE if action is aborted, goal is rejected or action server fails. While action is executing returns RUNNING.

Port	In / Out	Description
max_speed	In	Maximum speed in meters per second.
pose	In	Goal pose in meters (e.g. x;y;z).
yaw_angle	In	Yaw angle in radians.
yaw_mode	In	Yaw mode (KEEP_YAW = 0; PATH_FACING = 1; FIXED_YAW = 2).

GoTo GPS

Go to specified GPS position with given maximum speed and yaw.

Returns SUCCESS if action finishes successfully or cancelled. Returns FAILURE if action is aborted, goal is rejected or action server fails. While action is executing returns RUNNING.

Port	In / Out	Description
alittude	In	Altitude in meters.
latitude	In	Latitude in degrees.
longitude	In	Longitude in degrees.
max_speed	In	Maximum speed in meters per second.
yaw_angle	In	Yaw angle in radians.
yaw_mode	In	Yaw mode (KEEP_YAW = 0; PATH_FACING = 1; FIXED_YAW = 2).

Land

Land at current position with given speed.

Returns SUCCESS if action finishes successfully or cancelled. Returns FAILURE if action is aborted, goal is rejected or action server fails. While action is executing returns RUNNING.

Port	In / Out	Description
speed	In	Land speed in meters per second.

Offboard

Set offboard mode. Input port is not intended to use by the user, but used because nav2_behavior_tree service action node implementation.

Returns SUCCESS if service result is true. Otherwise, returns FAILURE.

Port	In / Out	Description
service_name	In	Service name which will be called.

SendEvent

Send event by topic.

Always returns SUCCESS after sending the event.

Port	In / Out	Description
data	In	Data to send (string).
topic_name	In	Topic name where data will be sent.

Takeoff

Takeoff at current position with given height and speed.

Returns SUCCESS if action finishes successfully or cancelled. Returns FAILURE if action is aborted, goal is rejected or action server fails. While action is executing returns RUNNING.

Port	In / Out	Description
height	In	Takeoff height in meters.
speed	In	Takeoff speed in meters per second.

Condition

Show Conditions

IsFlying

Returns wheter the drone is flying or not.

Returns SUCCESS is drone state is flying, otherwise returns FAILURE.

Control

-

Decorator

Show Decorators

WaitForEvent

Listens for event received in topic and outputs event msg content.

Returns SUCCESS on first event received, until that returns RUNNING.

Port	In / Out	Description
topic_name	In	Topic name where event will be published.
result	Out	Content of event msg.