Strapdown Inertial Navigation System And Doppler Velocity Log Study On Underwater Integrated Navigation Algorithm

With the gradual deepening of China’s strategy of maritime power,underwater spacecraft has become a hot topic of Marine science and technology research,which has attracted wide attention in both the military and civilian fields.In view of the complex and changeable underwater environment and the growing requirements of underwater navigation tasks,the inertial navigation system combined with Strapdown Inertial Navigation System and Doppler Velocity Log has paid widespread attention in the field of underwater navigation due to its own complete independence,concealment,autonomy and high precision.Using underwater spacecraft to achieve underwater tasks is the current development trend,and accurate positioning of the carrier position is also an important premise for the underwater spacecraft to effectively and realize the task safely.Therefore,the research and development of SINS /DVL integrated navigation technology is of great significance.In recent years,it has gradually become a hot spot in the field of underwater spacecraft.The SINS receives the velocity measurement information from the DVL,and then integrates with the posture,velocity and position information obtained by its own inertial solution,which can periodically suppress the accumulation of self-localization error and keep the error from diverging.In the actual use of the combined navigation system,affected by the environment,the heading angular error after the coarse alignment and the zero deviation error of the inertial device itself cannot be ignored.The coupling of the two magnifies the attitude angular error and speed error in the navigation process,which leads to the decline of the combined navigation accuracy.In addition,in the actual use of SINS / DVL integrated navigation,the statistical characteristics of DVL measurement noise will change with time due to the complex underwater environment,and the DVL measurement noise statistical characteristics set at the initial time of filtering are usually inaccurate,or the accurate DVL measurement noise statistical characteristics have been determined at the initial time,but the noise statistical characteristics have changed with time.Therefore,the inaccuracy of DVL measurement noise statistics is also a common problem during underwater navigation.To this end,this paper will deeply study the combined navigation performance optimization technology in a complex water-acoustic environment,aiming to further improve the accuracy and stability of the SINS / DVL integrated navigation.In the case of large heading angle error and unknown zero deviation of inertia device after coarse alignment,we introduce a fine alignment algorithm based on Kalman filter and determine the observability of the state to be estimated and then design the corresponding mobility scheme.Dynamic base precision alignment under this maneuver scheme can effectively estimate the initial heading angle,gyroscope,and accelerometer zero bias,laying the foundation for the subsequent integrated navigation phase.For the problem of time-varying noise statistical characteristics of Doppler meters,this paper introduces an adaptive integrated navigation filtering algorithm based on Allan variance estimation and introduces Allan variance estimation into the Kalman filter-based combined navigation algorithm to effectively suppress the error caused by the time-varying nature of the noise statistical characteristics of Doppler meters.