# An Adaptive Fault-Tolerant Federated Kalman Filter for a Multi-Sensor Integrated Navigation System

## TL;DR

This paper introduces a new adaptive filter to improve navigation system reliability by handling sensor errors and outliers.

## Contribution

The novel AFTFKF integrates adaptive noise estimation and outlier detection for robust multi-sensor navigation.

## Key findings

- The proposed AFTFKF improves accuracy in outlier-prone navigation scenarios.
- SPRT-MLE and DCST methods effectively handle both slow and abrupt outlier changes.
- Simulation results confirm strong stability and performance in integrated navigation systems.

## Abstract

To achieve autonomous and reliable all-weather cross-domain aerospace navigation, this study proposes an adaptive fault-tolerant federated Kalman filter (AFTFKF) for an INS/SRNS/CNS integrated navigation system to enhance system robustness against measurement outliers. First, a noise estimator based on maximum likelihood estimation (MLE) and aided by a sequential probability ratio test (SPRT) is introduced to handle slowly growing outliers. Second, a double residual-based Chi-square test (DCST) information factor is designed to mitigate the impact of inaccurate local state estimation in subsystems under abruptly changed outliers. Finally, the SPRT-MLE-based noise estimator and the DCST-based information factor are integrated into the federated Kalman filter framework to construct the complete AFTFKF. Simulation results demonstrate that the proposed method achieves superior accuracy and strong stability for SINS/SRNS/CNS integrated navigation in the presence of outliers.