Heave measurement algorithm for strapdown inertial Navigation system based on adaptive multiple low-pass filter

The traditional heave measurement algorithm based on inertia technology and digital high pass filter leads to the heave measurement error due to the phase advance of the output signal. The article analyzes the function and error characteristics of the digital high-pass filter. A strapdown inertial navigation heave measurement algorithm based on adaptive multiple low-pass filter (AMLF) is proposed to solve the phase lead error introduced by the characteristics of digital high-pass filter. First, the accelerometer in the strapdown inertial navigation measures the wave motion information and identifies the dominant frequency of the wave motion. Then introduce a low-pass filter with parameters that can be adjusted in real time with the dominant frequency of the ocean wave to filter out the low-frequency error signal in the accelerometer measurement information. Finally, the real heave information can be obtained by subtracting the filtered error signal from the original signal measured by the accelerometer. The algorithm solves the problem that the digital high-pass filter leads the phase of the heave measurement signal. The simulation results show that the heave measurement accuracy of the proposed algorithm is within 5cm, which improves the real-time performance and accuracy of heave measurement.