Constraint model-based planning and scheduling with multiple resources and complex collaboration schema

Christophe GUETTIER, Bertrand Allo, Vincent Legendre, Jean-Clair Poncet, Nelly Lecubin

Abstract:

In many domains, planning and scheduling problems have
been considered separately. This historical decomposition
leads to sub-optimal solving methods as task scheduling and
planning share important sub-problems. In fact, on practical
examples, there is no reason to separate coordination of
activities and synchronization tasks. Furthermore, resource
usage is not only relevant for task scheduling problems, but
is also strongly affected by planning decisions in real-world
problems. This paper proposes a Constraint Model-Based approach
to concurrently tackle planning and scheduling problems.
We show how constraint-based formulations can take
advantage of flow models widely investigated in the operation
research community. Our approach extends this model
classification in order to derive both timing constraint and resource
consumption for each transition of the plan. Therefore,
scheduling constraints involving precedences, exclusive
disjunctions, and resource capacity limit can be stated over
the set of timing and resource variables. On aeronautic and
spatial examples, we demonstrate how this approach enables
problem-dependent specialization and increases planning and
scheduling efficiency. Lastly, by using real-world problem
experimentations, we show how the approach supports local
/ global trade-offs while designing solving methods.