Peter Aronsson

OpenModelica - A free open-source environment for system modeling, simulation, and teaching

Modelica is a modern, strongly typed, declarative, and object-oriented language for modeling and simulation of complex systems. This paper gives a quick overview of some aspects of the OpenModelica environment - an open-source environment for modeling, simulation, and development of Modelica applications. An introduction of the objectives of the environment is given, an overview of the architecture is outlined and a number of examples are illustrated.

Formal Semantics Based Translator Generation and Tool Development in Practice

In this paper we report on a long-term research effort to develop and use efficient language implementation generators in practice. The generator is applied to a number of different languages, some of which are used for projects in industry. The used formal specification style is Operational Semantics, primarily in the form called Natural Semantics, represented and supported by a meta-language and tool called the Relational Meta Language (RML), which can generate efficient implementations in C, on par with hand-implemented code. Generating implementations from formal specifications are assumed to give advantages such as: high level descriptions, higher degree of correctness, and consistency between specification and implementation. To what extent can this be realized in practice? Does it scale to large language implementations? To answer some of these questions we have developed specifications of a range of languages: imperative, functional, object-oriented (Java), and equation-based (Modelica). The size of specifications range from half a page to large specifications of 60 000 lines. It turns out to be possible to generate efficient compilers, also for large languages. However, the performance of the generator tool and the user support of the development environment become increasingly important for large specifications. To satisfy such user needs the speed of the generator was increased a factor of ten to reduce turn-around time, and an Eclipse plug-in including a debugger were developed. For very large specifications, the structuring and modularity of the specification itself also become essential for performance and maintainability.

Vision system for monitoring the production of corrugated cardboard

In this paper a vision system for the control quality in a factory of corrugated cardboard is described. The problem under study is the automatic detection and monitoring of the sheets of cardboard constituting a unit of sale. A precise measurement of the number of sheets is a difficult task, since, during the process, some sheets must be discarded, because of their inferior quality, or because they have been damaged during the transport. Usually, the number of the sheets is estimated from the ratio between the weight of the unit and the nominal weight of a single sheet. Since the weight of a sheet is uncertain, an estimation based on the weight ratio is poor and its reliability is very low. A different solution is proposed in this paper: it estimates the number of the sheets via a suitable vision system. It offers a very high precision (the middle error is smaller of 2%) and it has the advantages to avoid invasive interactions with the process of production and to be a low cost solution.