Many companies claim to offer open control systems, since they use widely used technology, even if it is proprietary; or they publish their technology and think that now they can call it open, without releasing control. The result is monolithic solutions. In our opinion, an open control systems can be called open if

• it is component based,
• the component interfaces are
• vendor independent,
• are not encumbered by ownership or patent protection
• are a result of a consensus (i.e. a priori, e.g. IEC-61131-3),
• reflect proprietary practice and technology with control released by initiator (i.e. a posteriori, e.g. TCP/IP).

Certainly, openness can so be realized at different levels, in more or less layers, depending on the granularity of the systems. What remains common for all, however, is that due to non-proprietary interfaces, true free economy and competition is possible. For the end-user the result is choice, and not being locked in to a solution as any component can be exchanged by a competitor's one, due to the non-proprietary interface.

The concept of open control can be applied to different domains of control, with different requirements, such as :

LinuxPLC, aka MAT (Machine Automation Tools), Programmable logic controller software with PLC tasks running as Linux processes. Very elegant solution, based on Petri Netroworks and completely open source.

PuffinSCADA, a UNIX based software collection to implement SCADA systems with an extremely modular design, with clients and servers.

MCA, the modular control architecture, mainly targeted to robot control and based upon reusable software modules. Any controller can be implemented from C++ objects providing four edges: sensor and controller input and output.

OMAC, the open modular architecture controller. An effort towards intelligent machine control on an abstract system wide level, mainly user driven, pragmatic and adherend of open= widely used.

ORCOS, Open source RObot COntrol Software, is a new open source project for robot control, the design and implementation of a framework for real-time motion control.

The fact that all over the word open control efforts are popping up can be taken as indice for a necessity. Bringing them together in order to work out an open control and component based architecture is the next challenge. Control.com provides the forum to persue this vision.

Publications and scientific work

P. Wurmsdobler: Component Based Controller Architecture. A draft. 2002.
Available as More Informatiion.

P. Wurmsdobler: Open control systems : architecture, problems and solutions. Talk at Colloquium at the Department for Computer Science, Boston University, Boston, 2002.
Available as PDF Document.

P. Wurmsdobler: Linux for real-time PLC control? Slower is easier. In InTech by the Instrumentation, Systems and Automation Society, www.isa.org, 2001
Available as PDF Document.

Wurmsdobler, P. and M de Sousa: OPEN CONTROL SYSTEMS. In Proceedings of the third Real-Time Linux Workshop, Milano, 2001.
More information