Optimal redundant sensor configuration for accuracy increasing in space inertial navigation system

A redundant inertial measurement unit (IMU) is an inertial sensing device composed by more than three accelerometers and three gyroscopes. This paper analyzes the performance of redundant IMUs and their various sensors configurations. The inertial instruments can achieve high reliability for long periods of time only by redundancy. By suitable geometric configurations it is possible to extract the maximum amount of reliability and accuracy from a given number of redundant single-degree-of-freedom gyros or accelerometers. This paper gives general derivation of the optimum matrix which can be applied to the outputs of any combination of 3 or more sensors to obtain 3 orthogonal vector components based on their geometric configuration and error characteristics. Certain combinations of 4 or more instruments have the capability of detecting an instrument malfunction, those of 5 additional capabilities of isolating that malfunction to a particular sensor.