Mascada (Esprit LTR 22728)
Manufacturing Control Systems Capable of Managing Production Change and Disturbances
The novel contributions, which the MASCADA project will make, are:
- Emergent Behavior in Manufacturing Control: Manufacturing control emerges from the behavior of agents comprising the control system; these agents represent manufacturing entities like "orders" or "conveyors" (not functions) and have expertise which relates to themselves only, including their linkages to the rest of the world (no global knowledge). - This results in an important property regarding the engineering of such an agent-based control system: Implementers only need to be experts on a narrow domain (e.g. on a transport system element, on a transport system aggregate, on the operating of a machine, ...). Also, because agents do not rely on knowledge/facts/expertise outside their own scope, these agents become re-usable and plug-able components. In addition, it is widely recognized in the software engineering community that entities are much more stable over time than functions.
- Pro-active Disturbance Handling: Disturbances will be treated as ‘business as usual’ when they occur, and in addition, the control system will proactively prepare the system by guiding it toward states where it is best able to handle and absorb disturbances that have previously been shown to have considerable impact on production goals.
- Throughput Safeguarding: Mascada will develop manufacturing control solutions which achieve a minimum reduction in production throughput in the face of (unpredictable) operational disturbances and longer term change. To achieve this, Mascada control solutions will account for the specificity of the embedded manufacturing processes and equipment, of the transport and storage system’s elements, and of the system configuration. - The above re-usability and plug-ability of the agents makes it economically feasible to account such specific knowledge. Indeed, when for instance a production process is developed or acquired, the development of a single agent reflecting the properties of this process represents only a small fraction of the overall effort. In contrast, making functional components account for such specificity requires the prohibitive software maintenance efforts that are experienced in today’s practice.
- Hot Plug-able Agents: It shall be possible to add, remove and change agents while production continues - provided this is done judiciously.
In addition, Mascada envisages developments that will facilitate the take-up of results: (1) the use of detailed digital mock-ups; (2) an agent architecture aimed at the industrial control environment; (3) guidelines derived from the experience with the test bed and the demonstrators.