Enhancement of Integrated GPS/INS Performance Utilizing Frequency Domain Implementation of INS Calibration

: A new approach for improving integrated GPS/INS performance is presented. The approach is based on frequency-domain mechanization of the INS algorithms. The frequency-domain development proposed is motivated by the existing imbalance between conventional INS algorithms and current DSP technology, as well as the recent evolution of GPS block processing techniques that have the promise to significantly enhance GPS performance. The new approach focuses on the implementation of frequency-domain in-flight calibration techniques to achieve centimeter-level accuracy when GPS is integrated with a low-grade INS. This paper demonstrates that the proposed frequency-domain calibration approach allows for suppression of conventional calibration drawbacks. In particular, test results obtained indicate an order of magnitude reduction of errors caused by conventional representation of calibrated parameters (methodical errors). It is also shown that the proposed techniques can compensate for unbounded degradation of inertial accuracy in singularity (or poor observability) cases.