Ship Roll And Heave Based On Inertial Navigation Key Measurement Techniques Research

With the development of marine resources by humans,ships are essential tools.However,the unpredictable marine environment will cause the ship to move with six degrees of freedom,of which pitch,roll and heave movements have the greatest impact on the ship operation.Accurate measurement of ship roll and heave motion is an important prerequisite for maintaining a stable state on the sea surface,improving the safety and practicality of ships,and has practical engineering significance.Therefore,this article focuses on the measurement technology of ship roll and heave motion from the following aspects:(1)Starting from the theoretical part of the Strapdown Inertial Navigation System,this thesis introduces the principles of ship roll and heave measurement based on inertial navigation.Starting from the error equation of the inertial navigation system,the factors that affect the inaccurate measurement of ship roll and roll motion were obtained;Starting from the instability of Schuler oscillation and altitude channels,the factors affecting the inaccurate measurement of heave motion were identified.Finally,a detailed description was provided on how to experimentally verify the measurement of ship roll and heave on the experimental platform.(2)Use Kalman filtering to measure the longitudinal and transverse sway of ships.Firstly,the overall scheme of the ship roll measurement algorithm was elaborated.Secondly,in order to obtain accurate raw information for calculating the pitch and roll,an accelerometer and gyroscope error model was constructed,and error calibration experiments were conducted.Then,the principle of separately using gyroscopes and accelerometers for attitude calculation was introduced,and attitude experiments were conducted to verify the results.Finally,the principle of standard Kalman filtering was introduced.Due to the limitations of individual angle solving algorithms,Kalman filtering was used to fuse the two types of information,achieving complementarity.Due to the inaccuracy of Kalman filtering in nonlinearity,a quaternion extended Kalman filtering attitude model was proposed and experimentally validated.The experimental results verified that the algorithm based on quaternion Kalman filtering can accurately measure the pitch and roll angles of ships.(3)Measure ship heave using a digital high pass filter.Firstly,it introduces how to use analog low-pass filters to design digital high-pass filters.In order to obtain the optimal filter for heave measurement,experiments were conducted with different orders and cutoff frequencies to determine the optimal filter.However,the optimal filter designed has phase leading errors due to its own characteristics,which affect the real-time performance of ship heave measurement.Therefore,using the concept of complementarity,a complementary high pass filter with no delay was designed to improve real-time performance.Finally,its effectiveness was verified through experiments.(4)Use adaptive wave sensors to measure ship heave.Although complementary high pass filters can solve the problem of phase leading,their parameters are fixed,and their filtering effect weakens when sea conditions change.Therefore,an adaptive delay free digital high pass filter has been improved and designed.Firstly,a ship heave motion model has been constructed and frequency domain analysis of the heave motion has been conducted.Then,based on the analysis of filter error and sensor error,the optimal cutoff frequency of the adaptive filter is obtained and a self adaptive delay free digital high pass filter is designed.And simulate sea state experiments at all levels and conduct platform experiments.The maximum error and mean square error obtained by the fixed parameter complementary filter processing are more than twice the results of the adaptive delay free digital high pass filter processing.