Redundant information processing system

Abstract

A redundant information processing system with sufficient reliability is provided at a moderate cost without any part that could be a single fault point in the system. In the redundant information processing system in which an actuatoris controlled based on a signal from a sensor, each of processing devicesA toC collects command signals from other processing devices and determines which command signal to be valid according to a logical decision, for example, a majority decision. When the command signals of more than two of the processing devices including the relevant processing device which determines are valid, the command signals are output according to priority while a control information blocking signal is output to a processing device other than those which are valid. When command signals of processing devices other than one which determines is valid, a processor partdoes not output a command transmitting signal and does not either output the control information blocking signal to the other devices. When the number of control information blocking signals input from the other devices is less than two and the processor part outputs command transmitting signal, an interface partoutputs the command signal to the actuator. When the number of control information blocking signals input is two, the interface partdoes not output the command transmitting signal even if the processor part outputs that command transmitting signal.