BMFLC Algorithm for Ship Heave Measurement Based on Frequency Estimation

A band-limited multiple Fourier linear combiner (BMFLC) algorithm based on frequency estimation is proposed for the problem of scattering of data from the strapdown inertial navigation system due to low frequency interference and random wandering coefficients of inertial devices. Firstly, the relationship between the input signal frequency and the overrun angle is analyzed under the condition that the IIR filter is designed to cause the output phase overrun after the secondary integration of the acceleration data collected by the inertial measurement unit; Secondly, the signal frequency band is estimated based on Fast Fourier Transform (FFT) and the frequency of the heaving signal is corrected by the M-Rife algorithm; Finally, the phase angle and amplitude of the heave model are fitted by the BMFLC algorithm, and then the fitted trajectory curve is used to compensate for the error. The simulation results show that the designed improved BMFLC algorithm based on frequency estimation can well solve the error effects brought by the traditional digital filter and can realize the accurate measurement of the ship’s instantaneous line motion.