A Novel Tightly Coupled Attitude and Heading Measurement Method Based on Full-Sky Polarization Mode for Bionic Navigation System

The bionic navigation system composed of polarization sensor (PS)-aided inertial measurement unit could provide high-accuracy attitude and heading for unmanned vehicles in GNSS rejection or magnetic interference environments. However, the existing loosely coupled (LC) method is vulnerable to occlusion interference and atmospheric depolarization. Therefore, this article proposes the tightly coupled (TC) attitude and heading measurement method based on full-sky polarization mode. First, the TC system model is constructed, in which the sun azimuth error and zenith error are added to the state vector, and the angle of polarization (AOP) deviation of multiple observation channels are taken as the measurement. On this basis, a robust fusion mechanism based on the sequential cubature Kalman filter is proposed. And the linear gravity measurement update and the nonlinear polarization measurement update are carried out in turn to improves the system robustness. In the rotation test, the slight interference vehicle test, and the serious interference vehicle test, the heading root-mean-square error (RMSE) of the proposed method compared with that of the LC method are reduced by 32.5%, 32.3%, and 70.2%, respectively, which verifies the great advantages in practical unmanned driving applications.