Principles Involved in the LM Rendezvous Radar Redundant Gyro System

Abstract

For typical failure rates the probability of two or more of four gyros failing is very much less than one or both of two. Thus, a single redundancy system of four gyros greatly enhances system reliability. The orientation of the sensitive axes of four gyros is specified and means of generating outputs dependent only on gyro inconsistencies are defined. The voting logic and plots of switching decision zones are developed. The hardware required to implement this logic is shown to be simple and thus reliable. The use of rate integrating gyros requires the limitation of error integration time in order to avoid spurious failure signals. This is achieved by a reset cycle which realigns the four gyros at regular intervals. False error signals can be generated if inputs are large enough to exceed linear ranges of various components downstream of the gyros.