An Approach to Software Assisted Recovery from Hardware Transient Faults for Real Time Systems

Abstract

Most of the mission critical real time systems are characterized by the cyclical execution of periodic processes with hard deadlines. Provision of fault tolerance for such systems, has been extensively studied. Most of these treat hardware faults as belonging to the permanent stuck-at category. In this paper we deal with hardware transient faults, which by their intrinsic nature manifest as software faults and thereby lend themselves to correction based on concepts used in the study of software fault tolerance. This scheme which has been proposed to be used in real time embedded computers used in India’s satellite launch vehicle programs is simple to implement and uses an underlying process structure similar to the one proposed by Anderson and Knight [1]. It takes advantage of the natural synchronization existing in such processes and also the fact that the inertia of the physical systems in which these controllers are embedded absorb minor temporary deviations in their outputs so long as subsequent outputs are correct.