Real-time estimation of roll angles by magnetometer based on two-step adaptive Kalman filter

•The roll angle measurement model, the error model and the compensation model of the three-axis magnetometer are established, and the influence of random interferences generated by motors is discussed.•The application of robust estimation in the real-time calculation of ellipsoid fitting and roll angles is proposed to suppress the influence of random interferences.•The vector dot product invariant method is proposed to solve the problem that traditional methods cannot ultimately determine the coefficients of the error matrix.