As transistors scale down, systems are more vulnerable to faults. Their reliability consequently becomes the main concern, especially in safety-critical applications such as automotive sector, aeronautics or nuclear plants. Many methods have already been introduced to conceive fault-tolerant systems and therefore improve the reliability. Nevertheless, several of them are not suitable for real-time embedded systems since they incur significant overheads, other methods may be less intrusive but at the cost of being too specific to a dedicated system. The aim of this paper is to analyse a method making use of two task copies when on-line scheduling tasks on multiprocessor systems. This method can guarantee the system reliability without causing too much overhead and requiring any special hardware components. In addition, it remains general and thus applicable to large amount of systems. Last but not least, this paper studies two techniques of processor allocation policies: the exhaustive search and the first found solution search. It is shown that the exhaustive search is not necessary for efficient fault-tolerant scheduling and that the latter search significantly reduces the computation complexity, which is interesting for embedded systems.
CubeSats are small satellites operating in harsh space environment. In order to ensure correct functionality on board despite faults, fault tolerant techniques taking into account spatial, time and energy constraints should be considered. This paper presents a software-level solution taking advantage of several processors available on board. Two online scheduling algorithms are introduced and evaluated. The results show their performances and the trade-off between the rejection rate and energy consumption. Last but not least, it is stated that ordering policies achieving low rejection rate when using the algorithm scheduling all tasks as aperiodic are the "Earliest Deadline" and "Earliest Arrival Time". As for the algorithm treating arriving tasks as aperiodic or periodic tasks, the "Minimum Slack" ordering policy provides reasonable results.
The rapid aging of the population combined with the correlation between age and the increase in falls pushes us to create new ways to monitor the elderly. The privacy of radar data can respond to one of the weaknesses of existing technologies, but the huge amount of radar data to process becomes a challenge to process. We therefore introduce a first architecture allowing the processing of its data in real time. The radar technology used is an off-the-shelf Frequency Modulated Continuous Wave radar Ancortek (SDR 980AD2). It is followed by a pre-processing chain composed of Fast Fourier Transform, Filter and Short Time Fourier Transform to obtain time-velocity maps or spectrograms allowing the extraction of features from gait and human activities. An encouraging implementation (using SIMD logic) on Jetson Xavier allows us to move to data stream processing. Continuous monitoring of the subject will save lives, minimize injuries, reduce anxiety and prevent post-fall syndrome (PDS).
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