  While the benefits of reconfigurable manufacturing systems (RMS) are
well-known, there are still challenges to their development, including, among
others, a modular software architecture that enables rapid reconfiguration
without much reprogramming effort. Skill-based engineering improves software
modularity and increases the reconfiguration potential of RMS. Nevertheless, a
skills' composition framework with a focus on frequent and rapid software
changes is still missing. The Behavior trees (BTs) framework is a novel
approach, which enables intuitive design of modular hierarchical control
structures. BTs have been mostly explored from the AI and robotics
perspectives, and little work has been done in investigating their potential
for composing skills in the manufacturing domain. This paper proposes a
framework for skills' composition and execution in skill-based reconfigurable
cyber-physical production modules (RCPPMs). It is based on distributed BTs and
provides good integration between low-level devices' specific code and AI-based
task-oriented frameworks. We have implemented the provided models for the IEC
61499-based distributed automation controllers to show the instantiation of the
proposed framework with the specific industrial technology and enable its
evaluation by the automation community.
