Task and Motion Planning

We use PDDLStream to perform integrated task and motion planning (TAMP). This tool expands task planning with purely discrete parameters using Planning Domain Definition Language (PDDL) by adding the concept of streams for sampling continuous parameters in actions.

If you did not already install PDDLStream, ensure you do so with this script, then re-source.

./setup/setup_pddlstream.bash
source ./setup/source_pyrobosim.bash

Examples

Regardless of running PDDLStream standalone or using ROS2, we have included a set of examples that gradually build up from simple, purely discrete planning, to a more complex integrated TAMP demo with continuous action parameters.

The current example list is:

  • 01_simple - Simple domain with purely discrete actions

  • 02_derived - Purely discrete actions, but uses derived predicates for more complex goals

  • 03_nav_stream - Samples navigation poses and entire motion plan instances

  • 04_nav_manip_stream - Samples navigation poses, motion plans, and collision-free object placement instances

These PDDL domain and stream description files can be found in the pyrobosim/pyrobosim/data/pddlstream/domains folder.

Standalone

You can try running a sample script as follows

cd /path/to/pyrobosim/pyrobosim
python3 examples/demo_pddl.py --example 01_simple --verbose
PDDLStream standalone demo.

With ROS2

First, build and setup the colcon workspace (or use one of our provided Docker containers).

cd /path/to/colcon/workspace
colcon build
. install/local_setup.bash

With ROS2, the idea is to separate out functionality into different nodes.

To start a world and then a planner with a hard-coded goal specification:

ros2 run pyrobosim_ros demo_pddl_world.py
ros2 run pyrobosim_ros demo_pddl_planner.py --ros-args -p example:=01_simple -p subscribe:=false

To start a world, a planner, and a separate node that publishes a goal specification:

ros2 run pyrobosim_ros demo_pddl_world.py
ros2 run pyrobosim_ros demo_pddl_planner.py --ros-args -p example:=01_simple -p subscribe:=true
ros2 run pyrobosim_ros demo_pddl_goal_publisher.py --ros-args -p example:=01_simple

Alternatively, you can use a single launch file to run the full example and configure it:

ros2 launch pyrobosim_ros demo_pddl.launch.py example:=01_simple
ros2 launch pyrobosim_ros demo_pddl.launch.py example:=04_nav_manip_stream subscribe:=true verbose:=true

The output should look as follows:

PDDLStream demo with ROS2.