BehaviorTree EUT Plugins

This library witholds a small set of additional functionalities to be able to:

• Monitor
• Debug
• Replay

Behavior Trees implemented with the BehaviorTree.CPP library (tested with version 4.6.2).

How to compile it (ROS2)

At the moment the package compiles and has been tested with ROS2 humble, therefore compile using colcon build(ROS2) and making sure public BehaviorTree.CPP v4.6+ has been compiled and/or sourced correctly in the workspace.

Furthermore, make sure xmllint is installed.

apt -y install libxml2-utils

How to use it (ROS2)

For monitoring and debugging the tree just include the following headers:

#include "behaviortree_eut_plugins/eut_debug.h"
#include "behaviortree_eut_plugins/loggers/bt_zmq_publisher.h"

Create the tree with built-in functionalities of the libraries, such as createTreeFromFile(const std::filesystem::path& file_path, Blackboard::Ptr blackboard), making sure it is allocated dynamically to memory and therefore witholding a shared_ptr to it.

std::shared_ptr<BT::Tree> tree_ptr = std::make_shared<BT::Tree>(factory.createTreeFromFile(tree_file_path));
BT::DebuggableTree debugTree{tree_ptr};

BT::Tree& tree = *(tree_ptr); // if you wanna have a direct ref. to the object

If you want to enable monitoring, just instantiate a ZMQPublisher and then you can just tick your tree as you normally do:

// Connect the PublisherZMQ. This will allow GrootEUT to
// get the tree and poll status updates.
const unsigned port = 1667;
BT::PublisherZMQ publisher(debugTree, port);

...

  while(1)
  {
    tree.tickWhileRunning();
    std::this_thread::sleep_for(std::chrono::milliseconds(2000));
  }

Monitor and debug your tree through the monitoring functionality available in Groot humble branch.

Additional details you might be interested to

DebuggableTree options

Note that this is the constructor for DebuggableTree

DebuggableTree(std::shared_ptr<Tree> tree, bool pausable = true, bool start_paused = true)

In details:

• start_paused it's a flag to pause before the first tick to the root, allowing you the possibility to play the tree directly from Groot
• pausable it's a flag to allow for the tree to be interacted with at run-time affecting its execution (pause/resume, breakpoints, enable, WoZ)

Treat custom types

Assuming you have your custom type Position2D:

struct Position2D
{
  double x;
  double y;
};

You need to define the macro to generate the code that is needed to convert the object to/from JSON

BT_JSON_CONVERTER(Position2D, pos)
{
  add_field("x", &pos.x);
  add_field("y", &pos.y);
}

You still need to call BT::RegisterJsonDefinition<Position2D>() before instantiating the tree and use monitoring, otherwise object cannot be serialized and sent to the monitoring tool (e.g. Groot).

BT::RegisterJsonDefinition<Position2D>();

Examples

I invite you to take a look at the examples under src/examples(ROS2) for more details.

If you're stucked or whatever issue arise, please ping Devis (devis.dalmoro@eurecat.org) or David (david.calero@eurecat.org) to avoid wasting any time on it