Fault detection approach applied to inertial navigation system/air data system integrated navigation system with time‐offset

The false alarm of a fault detection module in aircraft will interfere with flight. If there is a time‐offset between the inertial navigation system (INS) and air data system (ADS), the probability of a false alarm (PFA) of the fault detection module will increase, which is ignored in existing approaches. To address the problem, a fault detection approach is proposed applied to INS/ADS with a time‐offset. An INS/ADS fault detection model based on kinematic equations is developed, and we combine an unscented Kalman filter (UKF) with Runge‐Kutta to deal with the non‐linear and discretisation problem. A time‐offset estimator is designed and the observability of time‐offset is analysed, showing that time‐offset is observable only in the manoeuvre phase. A fault detection architecture applied to INS/ADS with a time‐offset is designed, which solves the problem of the high PFA of INS/ADS fault detection under a time‐offset. Simulation results show that under multiple time‐offset scenarios, the root mean square error of the proposed approach can reach 0.0134 s minimally, and after time alignment, the PFA of the fault detection can be reduced to 1.8%.