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We introduce a new methodology for the specification and the design of the control logic of automated manufacturing systems. Our aim is to make specification express just what is necessary earlier in the design process. This permits to produce an optimized work cycle for the system and makes both production recovery calculation and code generation easier. The methodology is based on a modular modeling...
Because a real-time system combines control and data processing designers specify it using different languages. Such systems are often distributed and the problem is to obtain a distributed implementation from these distinct specifications. Indeed, the method based on separated code generation and manual distribution leads to inconsistent implementations. We propose to unify all these specifications...
The use of Petri nets for the modelling of discrete-event systems is well-studied. Yet, the tools allowing the implementation of these models, and supporting code generation, are still very few, almost non-existent. This paper starts by presenting a Petri net class, based on place/transition nets and well-known concepts from synchronised and interpreted Petri nets. This Petri net class allows the...
In current embedded system design practice, only few architectural solutions and mappings of the functionalities of a system on the architecture's components are examined. This paper presents an optimization-based method and the associated tool developed to help designers take architectural decisions. The principle of this approach is to efficiently explore the design space and to dynamically provide...
This paper presents the planned and on-going activities inside the FORDESIGN research project, funded by the Portuguese FCT (Foundation for Science and Technology), whose main objective is to foster the effective use of formal methods for embedded systems co-design. The project proposes a methodology where the use-cases are used as a starting point, not only for capturing requirements but also to...
The real-time specification for Java (RTSJ) introduces a new memory model featuring some programming constraints that impede the "as-is" use of many well known design patterns. In this context, this paper describes and evaluates two design patterns, developed by the authors for distributed real-time Java software, that are able to overcome the limitations imposed by RTSJ. The first pattern,...
Through a new computing paradigm, the wireless sensor networks revolutionize the environment monitoring, enabling applications in a wide range of knowledge areas. However, the process of creating these applications for these networks is still not simple, depending on the target operating system and hardware. In order to fill this gap, we developed a new programming model and a framework able to generate...
The maintenance of systems involved in production processes must be carried out with maximum efficiency and minimum downtime, especially on time-critical systems (operation times are included between a minimum and a maximum value). This paper presents a proactive/reactive control to fit preventive maintenance into a busy production schedule. As preventive maintenance is regarded as a non-preemptive...
The increasing complexity of productive systems associated with the geographical dispersion of industries motivates new demands and the adoption of new design tools. In this context the purpose of this work is to introduce a new platform for distributed modeling and analyses of productive systems. The platform is based on Petri net as a modeling formalism and on the label-ring protocol for managing...
In this paper we propose a system architecture that supports end-to-end scheduling of the distributed real-time thread abstraction. The real-time specification for Java (RTSJ) is used for the implementation of distributed real-time threads. By using simulations, we conclude that the proposed architecture is flexible enough to accommodate different scheduling algorithms
Hierarchical communicating real-time state machines (H-CRSM) is a formal modelling language for the modular development of distributed real-time systems. The formalism is characterized by the use of state transitions with guarded commands and timing constraints, the adoption of a few distilled statecharts constructs, and the modular specification of timing constraints along a state hierarchy. This...
At present, a number of platforms are becoming available for the implementation of intelligent field devices, which are based on low-cost microcontrollers and open-source real-time operating systems. To take full benefit from these platforms and to ease the task of developing and porting the application software, a standard interface has to be provided to cope with communication facilities. In this...
This paper discusses a new approach to the development life-cycle of agent-based production control applications, from the design to the operation, based in a catalogue of high-level Petri nets. The high-level Petri net-based approach facilitates the conception, definition and formal specification of an "encapsulation process" in industrial production systems. The catalogue includes elements...
In the paper the method of computation all deadlocks and traps in the Petri net is presented. This method is based on Thelen method. Methods of calculation of all deadlocks and traps in Petri nets are very time consuming. Therefore it is very important to optimize a computation. The parallel computation method for the time reduction is proposed. Experimental results of presented method are discussed,...
In this paper an approach for the transparent use of real-time Java in control and automation is described. The proposed approach, which is in the context of the model integrated mechatronics paradigm, exploits the function block (FB) construct for the design model and the real-time Java specification for the implementation one. Specific interpreters allow for the automatic generation of FB types'...
Temporal correctness is crucial for the dependability of real-time control systems. A problem with testing such systems is the dependency on the execution orders of tasks. Mutation-based testing criteria have been proposed to determine which execution orders need to be exercised to verify that real-time systems are timely. For flexible control systems, timeliness in itself may only be relevant for...
This paper describes formal modeling and verification of automation systems from the system engineering point of view. Reuse of model components is the key issue in order to bring the scientific modeling methodology into engineering practice. The reuse is achieved by the combination of modular modeling of automation systems with object-oriented description of models in UML style. This allows to benefit...
In distributed systems the communication paradigm used for intertask interaction is the message exchange. Several approaches have been proposed that allow the specification of the dataflow between tasks, but in realtime systems a more accurate definition of these data flows is mandatory. Namely, the specification of the required tasks' and messages' parameters and the derivation of the unspecified...
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