The ORCA project is detailed in "ORCA-FMS: a dynamic architecture for the optimized and reactive control of flexible manufacturing scheduling" in Computer in Industry, 65(4), 706-720 (Pach, Berger, Bonte, &Trentesaux, 2014).

ORCA is an hybrid control architecture with capability to switch dynamically and partially between hierarchical predictive architecture and heterarchical reactive architecture, when is needed. Even ORCA was designed to can be applied to several domains, in the ORCA-FMS project was applied to a manufacturing scheduling of a Flexible Manufacturing Systems (FMS).

Global Control

From a predictive perspective, ORCA-FMS implements an Integer Linear Programming (ILP) model to schedule the FMS. It was modeled a flexible job shop problem (FJSP) as close as possible to reality as it contains original constraints from the manufacturing environment. In fact, the ILP resolve the machine allocation at the scheduling problem. The FJSP is detailed in the cited article.

Local Control

From a reactive perspective, ORCA-FMS implements a potential fields' approach to facilitate the reactivity after perturbations. This approach creates signals in the fixed machines enable to feature signal emissions for attracting moving products. The product evaluates and chooses dynamically the machine allocation and the product routing according the comparisons on the potential fields at each machine and the resulting shortest path. The Potential fields approach is detailed in the cited article. 

Integration of the Global and Local Control

The integration process is the following:

• At normal mode, the ILP provides the products with machine sequence data at the beginning of the production. The intelligent products will follow the sequence provided (Machine allocation) but routing decisions remains to be locally determined.
• At perturbation mode, once the uncertainty is detected, the affected intelligent products switch-down to disrupted mode. These set of products (Partial set) cease to follow the instructions from ILP and starts deciding the machine allocation and the routing. Not affected products stays in normal mode.

You will find here how to use the ILP