PDDL Integration for CLIPS
==========================

This extension provides an implementation for using PDDL alongside CLIPS.

If you need one of the following features, you may find this useful:

- A structured model of action and change to progress the CLIPS fact base according to a robots actions
- Unified sanity checks to ensure actions can only be executed if conditions are currently met according to the fact base
- Automated planning to reach complex objectives by means of computing and executing plans consisting of individual robot actions

Background: PDDL
++++++++++++++++

The Planning Domain Definition Language (PDDL) is the de facto standard language for expressing planning problems in artificial intelligence.
A PDDL problem consists of

 - a domain description, which defines the available objects, predicates, actions and their preconditions and effects,
 - a problem description, which specifies the initial state and desired goals.

Given such a description, a PDDL planner computes a sequence of actions (a plan) that transforms the initial state into one that satisfies the goal conditions.

An example PDDL problem can be found `here <pddl/domain.html>`_.


Overview
++++++++

This extension leverages the `Unified Planning Framework (UPF)`_, which supports a wide range of PDDL standards.
UPF is wrapped and exposed as a ROS node, hence interfacing is done via the regular |CX| plugins.

In order to reduce the manual overhead, an optional CLIPS abstraction layer is provided, which takes care of the ROS communication.

Additionally, this extension contain the `NEXTFLAP planner`_, which can handle both classical and temporal PDDL variants.
This planner requires the `z3 constraint solver`_, which is also provided.

Content
+++++++

.. toctree::
   :maxdepth: 2

   pddl/usage.rst
   pddl/pddl_clips.rst
   pddl/domain.rst
   pddl/raw_tutorial.rst
   pddl/structured_tutorial.rst