Abstract: The performance of a failure detection and isolation(FDI) algorithm applied to a redundant strapdown inertial measurement unit (IMU) is limited by sensor errors such as input misalignment, scale factor errors, and biases. A separated-bias estimation method is applied to obtain estimates of those combinations of sensor errors that affect the parity vector. These estimates are used to form a compensated parity vector which does not include the effects of sensor errors. The compensated parity vector is then used in place of the un-eompensated parity vector to make FDI decision tor improving FDI performance. The parity vector compensation algorithm will allow the reduction or elimination o! dynamic thresholds, and permit detect;on of soft failure during rapid vehicle maneuvers. In this paper the problem of noise compensation for FDI systems is also presented. Simulation result shows that the parity vector compensation algorithm can significantly improve FDI performance, especially during vehicle maneuvers.

Key words: failures, parity rector, sensor errors