Dependable onboard computer systems with a new method-stepwise negotiating voting

An algorithm for software voting, called stepwise negotiating voting, which can tolerate the faults in up to N-1 subsystems is introduced. The voter behaves as if it were a majority voter if the number of remaining subsystems is sufficient for majority voting, and standby redundancy is realized if the number of remaining subsystems becomes insufficient. With this voting method, the system can survive if more than one subsystem remains. The authors introduce a method for evaluating the dependability of systems. It is based on the viewpoint that not only the hardware reliability but also the reliability of data processing is important. It is assumed that only transient faults take place in the software behavior. The author´s concept can be applied to computers in critical application fields, such as space development or engine control.<>