Accommodation rule with faulty sensors based on system performance

We consider a fault accommodation problem when some faults occur in gyros and accelerometers in inertial navigation systems that use redundant sensors. The more sensors we use, the better the navigation performance of inertial navigation systems, which means that the error covariance of the position estimate becomes less. Thus if there are small faults in sensors, then it can happen that we better use faulty sensors instead of excluding those sensors. We suggest a threshold to decide on the exclusion of faulty sensor for single fault case and exclusion rule for double fault case, based on navigation performance.