Dynamic Decision Elements for 3-Unit Systems

Simple triplication is widely analyzed either as a static redundancy by itself or as an active core for dynamic redundancy. Its practical value was tested when it was used to protect the hardcore test and repair processor (TARP) of JPL STAR computer and the CPU of Guidance Computer for SATURN V. Two current techniques for using triplicated modules are TMR and TMR/Simplex. In this paper a set of dynamic decision techniques is proposed for better use of triplication, assuming Pr {system is in a specified failure mode | system has failed} is known for all failure modes of concern.