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What is GLACIER?

GLACIER is an open-source ecosystem for designing, prototyping, monitoring and optimising cyber-physical production systems (CPPSs). It is developed at the Department of Engineering for Innovation Medicine of the University of Verona.

The problem

Software is now a large part of what a manufacturing system is. A production line is a collection of machines, sensors and actuators, coordinated by control software that schedules work, reacts to sensor events and reports status upstream.

That software is difficult to develop, for a practical reason: the machine it controls is expensive, shared, and often not finished yet. Testing a scheduler against a real production line means booking the line, and a mistake can damage equipment or scrap material. So control software tends to be written late, tested little, and debugged on the plant floor.

The approach

GLACIER's answer is to give the control software something to talk to before the machine is available.

Each machine is described by a data model: a tree of variables (its state) and methods (its operations), declared in YAML. Control software interacts with the machine only through that data model — reading variables, writing variables, invoking methods and subscribing to changes.

Because the interface is explicit and declared separately from the implementation, the thing behind it can be swapped:

  • a simulated machine, whose behaviour is implemented in code, so the control software can be developed and tested offline;
  • a remote machine, reached through a connector to an OPC UA server or an MQTT broker, so the same control software can be pointed at real equipment.

The simulated side is built with Frost, which runs on Lingua Franca. Lingua Franca gives Frost a deterministic, logical-time execution model, so a scenario replays identically run after run — which is what makes a failing test reproducible.

What GLACIER does not claim

GLACIER is a research project, and it is worth being precise about the extent of what is implemented today.

  • Fidelity is up to you. Frost provides the interface, the messaging and the execution model. How faithfully a FrostReactor reproduces the timing and physics of the machine it stands for is entirely a property of the behaviour you write inside it. Frost does not itself supply validated physical models.
  • Determinism is about execution, not about physics. Lingua Franca guarantees a deterministic ordering of events in logical time. It does not guarantee that a simulation matches the real machine's timing.
  • "Deploy with no changes" is a design goal, not a guarantee. The data model and connector layer exist precisely to keep control software independent of what sits behind the interface, and the connectors for OPC UA and MQTT are implemented. Whether a specific application transfers unchanged depends on that application.

Next

  • Architecture

    The layers of a GLACIER system and how a message travels through them.

    Architecture

  • Ecosystem

    The libraries and applications that make up GLACIER.

    Ecosystem