An adaptive fusion factor-based polarization sensor/sun sensor/IMU integrated navigation method for BAHRS

The bio-inspired attitude and heading reference system (BAHRS) is capable of providing a reliable solution for determining attitude and heading determination under conditions of global navigation satellite system (GNSS) signal degradation. A critical challenge in BAHRS data processing is the fusion of polarization sensor (PS) and sun sensor, which significantly impacts system performance. In existing studies, however, observation signals extracted from PS and sun sensor are independently used as measurements when fused with the inertial measurement unit (IMU). The accuracy of the measurements from PS and sun sensors is not assessed, resulting in degraded fusion system performance. To improve the navigation accuracy of BAHRS, an adaptive fusion factor-based PS/sun sensor/IMU fusion strategy is proposed. Specifically, the fusion factor can be dynamically adjusted online based on the accuracy of PS and sun sensor measurements. Consequently, the optimal sun vector can be calculated for fusion with IMU, enhancing BAHRS navigation performance. Moreover, a BAHRS architecture is designed with an integration of compound eye PS and sun sensor. Based on the multi-direction observation structure of compound eye PS, the reliable direction of polarization (e-vector) and sun vector information can be obtained simultaneously, which improve the environmental adaptability of BAHRS. Finally, the effectiveness of the proposed fusion strategy is verified by the simulation, static ground test and unmanned aerial vehicle (UAV) flight test.