SEQUENCING TASKS TO MINIMIZE THE EFFECTS OF NEAR-COINCIDENT FAULTS INTMR CONTROLLER COMPUTERS

Although Triple Modular Redundancy (TMR) has been widely used to mask the effects of a single faulty module, it cannot tolerate coincident f aults in multiple modules caused by a common source, such as an enviro nmental disruption or malfunction of a shared component. We propose a method to eliminate or alleviate the effects of (near) coincident faul ts by sequencing tasks on different modules in a TMR system. Specifica lly, we develop an effective sequencing of tasks to simply place an '' optimal'' distance (in the sense of minimizing the mean number of faul ty tasks due to TMR failures) between the copies of a task to be execu ted on different modules. Several examples are presented, showing sign ificant improvements in reducing TMR failures with the proposed task s equencing.