narcispr / py_trees_meet_groot

Library to load XML behavior trees done using Groot GUI (https://github.com/BehaviorTree/Groot) into the py_trees library (https://github.com/splintered-reality/py_trees)

Import Groot XML files into py_trees

Groot is a Graphical Editor, written in C++ and Qt, to create BehaviorTrees. It is only compatible with BehaviorTree.CPP. This module is an attempt to use Groot to generate trees using py_trees instead of BehaviorTree.CPP.

The main purpose of this module is to load an XML file generated with Groot and transform it into a valif py_trees behavior tree. Execution of py_trees behavior trees is not connected to Groot for the moment.

Groot Behavior Tree	py_trees Behavior Tree

Groot supported features

BehaviorTree.CPP and py_trees use different control sequences, decorators and tree leaves. This section explains the mapping between one and the other in order to use Groot in py_trees.

Control nodes to Composite nodes:

Groot	py_trees
Sequence	Sequence with memory=True
ReactiveSequence	Sequence with memory=False
Fallback	Selector with memory=True
ReactiveFallback	Selector with memory=False
Parallel with success_threshold=1	Parallel with policy=SuccessOnOne
Parallel with success_threshold <> 1	Parallel with policy=SuccessOnAll
IfThenElse	not available
WhileDoElse	not available
SwitchX	not available

Decorators to Decorators

Groot	py_trees
Timeout	Timeout
ForceFailure	SuccessIsFailure
ForceSuccess	FailureIsSuccess
Inverter	Inverter
BlackboardCheckX	EternalGuard?
KeepRunningUntilFailure	Condition?
Repeat	not available
RetryUntilSuccessful	not available
Delay	not available
User defined Decorator	Decorator in decorators

Additional py_trees decorators, both core defined as OneShot, StatusToBlackboard, FailureIsRunning, RunningIsSuccess... or newly created by the user, must be added in the decorators diccionare and pass to the load function to be used.

Actions and Conditions to Behaviors

Groot	py_trees
AlwaysFailure	Failure
AlwaysSuccess	Success
SetBlackBoard	SetBlackboardVariable output_key=value
user defined Action	Behavior in user_behaviors
user defined Condition	Behavior in user_behaviors

All manually defined Actions and Conditions in Groot have to be defined as py_trees behaviors and added into the behaviors list in function load to be used.

Unsupported elements

The following elements are unsupported right now:

• Sub-trees
• Decorators with parameters
• Connecting the execution of py_trees to Groot

Example

import py_trees
from py_trees_meet_groot import groot_xml

# Define cusom Behaviors
behavior1 = py_trees.behaviours.Success(name="behavior1")
...
all_behaviors = [behavior1, behavior2, ...]

# Define any non-Groot decorator node
all_decorators = {}
one_shot = py_trees.decorators.OneShot
all_decorators["one_shot"] = one_shot
...

root = groot_xml.load("GROOT_XML_FILE_TO_LOAD.xml", behaviors=all_behaviors, decorators=all_decorators)