José Alberto Fonseca

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The requirement for flexible operation is becoming increasingly important in modern industrial systems. This requirement has to be supported at all system levels, including the field level in process industry, as well as the cell and machine control levels in manufacturing industry, where fieldbus-based communication systems are commonly found. Furthermore,(More)
Flexibility and safety are often considered conflicting concepts because flexibility implies dealing with changing requirements that can, in turn, produce unpredictable and possibly unsafe operating scenarios. Therefore, some in the automotive and avionic system design industry believe that a safety-critical system implies a fully static system in which all(More)
The traditional approaches to the design of distributed safety-critical systems, due to fault-tolerance reasons, have mostly considered static cyclic table-based traffic scheduling. However, there is a growing demand for operational flexibility and integration, mainly to improve efficiency in the use of system resources, with the network playing a central(More)
Non-preemptive scheduling is known for its lower efficiency in meeting temporal constraints when compared to preemptive scheduling. However, it is still used in certain cases such as in message scheduling over serial broadcast buses and in light multi-tasking kernels for embedded systems based on simple microprocessors. These cases are typically found in(More)
The amount of information that must be exchanged in modern Digital Computer Control Systems (DCCS) and real-time industrial automation is now reaching the limits that are achievable with traditional fieldbuses. Currently, Ethernet is increasingly used in DCCS, however, the available solutions to guarantee real-time behaviour in Ethernet are not well suited(More)
Road accidents have a dramatic social and economic impact on the society, a situation that fostered the research of mechanisms for increasing road safety. Many of these mechanisms require the ability of the vehicles to communicate among each other and/or with fixed road-side stations. Due to the inherent mobility constraints, wireless technologies play a(More)
Currently, there is a trend towards the implementation of industrial communication systems using wireless networks. However, keeping up with the timing constraints of real-time traffic in wireless environments is a hard task. The main reason is that real-time devices must share the same communication medium with timing unconstrained devices. The VTP-CSMA(More)
Traditional shared Ethernet networks have a non-deterministic behaviour, which impairs the support of real-time communication. In this paper, it is proposed a shared Ethernet deterministic architecture, able to interconnect sensors, controllers and actuators at the field level, allowing the coexistence of standard devices with enhanced (real-time) devices.(More)