Tolerating sensor timing faults in highly responsive hard real-timesystems
Poledna, S.
Computers, IEEE Transactions on
Volume 44, Issue 2, Feb 1995 Page(s):181 - 191
Digital Object Identifier 10.1109/12.364530
Summary: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 overload 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
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