Issue No. 02 - February (1995 vol. 44)
DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/12.364530
<p><it>Abstract—</it>Real-time systems that have to respond to environmental state changes within a very short latency period often use event-triggered task activation. If the system has to function correctly in the presence of sensor faults, event-triggered task activation is not reliable. Faulty sensors may cause task activations to occur too early, too late, or task activations are omitted entirely. In particular, early task activations can <it>overload</it> the system. Time-triggered task activation is reliable, but by defining a competitiveness ratio it is shown that the processor utilization for highly responsive tasks is unacceptably low. To overcome the problems of event-triggered task activation while preserving its good performance the task-splitting model is introduced. The task-splitting model integrates fault tolerance into the analysis and construction of hard real-time systems by using a combination of event-triggered and time-triggered task activation. Based on a general task model, it is independent of any particular scheduling algorithm. The result of this work has influenced the design of a new operating system which will be applied in a robust automotive engine controller of the next generation.</p><p><it>Index Terms—</it>Sensor timing faults, fault tolerance, hard real-time systems, event-triggered task activation, competitiveness of task activation.</p>
S. Poledna, "Tolerating Sensor Timing Faults in Highly Responsive Hard Real-Time Systems," in IEEE Transactions on Computers, vol. 44, no. , pp. 181-191, 1995.