PlanSys2 4.0.0 brings PDDL+ support and hardened ROS 2 planning framework

PlanSys2 4.0.0 has been released as a unified version for ROS 2 Humble, Jazzy, Kilted, and Lyrical. The framework, used in logistics robots and NASA's Astrobee, now covers PDDL from version 1.2 through PDDL+ including durative actions, numeric fluents, and timed processes. Kairos is now the default planner, and a new STN behavior tree builder preserves concurrency and time constraints during execution. The release was validated with sanitizers, fuzzing, and stress testing across three DDS implementations.

What's new in PlanSys2 4.0.0

• PDDL coverage expanded: Supports PDDL 1.2 through PDDL+, including STRIPS, typing, conditional effects, derived predicates, numeric fluents, durative actions, timed initial literals, PDDL3 preferences/constraints, object fluents, and PDDL+ processes/events
• New default planner: Kairos replaces previous planner; claimed to cover more of PDDL than any other planner with faster performance
• STN behavior tree builder: Now default; executes plans while preserving action concurrency and time constraints
• Hardened reliability: Handles arbitrary start order, process death/recovery with state restoration, lost messages, network delays, loaded systems, API misuse, and hostile inputs
• Validation: Tested with sanitizers, fuzzing, and stress bench across Fast DDS, Cyclone DDS, and Zenoh
• Single release for four ROS 2 distributions: Humble, Jazzy, Kilted, and Lyrical

Why it matters

PlanSys2 has become a baseline for task planning with LLMs in robotics, and this release's unified versioning across four ROS 2 distributions reduces maintenance fragmentation for researchers and companies deploying logistics or space robotics.