Research On The Key Technology Of Warship SINS/CNS/DVL Integrated Navigation System

For the surface ship,the method of obtaining the high precision navigation information without the Satellite Navigation System is a research focus in recent years.To resolve this problem,the integrated navigation method based on the Inertial Navigation System(INS)/Celestial Navigation System(CNS)/Doppler Velocity Log(DVL)can be introduced,which means that the divergence error of the INS can be corrected by the reference navigation information from the CNS and DVL.Therefore,the navigation information with high precision can be obtained.However,the velocity information from DVL is influenced by the measurement noise,and the position information from CNS is influenced by the weather.Therefore,the reference information precision for the integrated navigation system is reduced.The integrated navigation method under the complex environment based on the INS/CNS/DVL is the main research problem in this paper,and the integrated navigation scheme can be improved by improving the referenced information precision.The main work in this paper is described as follows:For the integrated navigation method assisted by DVL,the design principle of the vehicle's motion path,which means all of the state variables can be estimated,is obtained by derivation and decomposition the observability matrix.Hence,the navigation error can be estimated and the accuracy of the integrated navigation system is improved.According to the problem of the measurement noise of DVL,the integrated navigation method based on the adaptive two-stage Kalman Filter is proposed by modelling and parameter deduction.The influence caused by the DVL measurement noise on the integrated navigation can be avoideds.For the integrated navigation method assisted by the Star Sensor(the CNS sensor),the research of the Inertial Measurement Unit(IMU)on-line calibration and correcting the navigation error is carried out:firstly,the dynamic equation and the measurement equation based on the-error quaternion are derived,and then,the design principle of the on-line calibration motion path is obtained by the observability analysis;according the characteristics of introducing the level attitude and the position in the navigation information calculating process for the Star Sensor,the integrated navigation methods based on the attitude coupling and the optimal estimation are obtained respectively.The applicability of these two integrated navigation method is analyzed.In order to resolve the problem of the accuracy of the Star Sensor is reduced by the installing it on the surface ship,the improved BP Neural Network(BPNN)is introduced in the INS/Star Sensor integrated navigation system.Firstly,the method of designing the initial weights and the thresholds of the BPNN is proposed.And then,based on the setting initial weights and the thresholds,the BPNN can be trained by the "history data",which is the navigation information calculating from the integrated navigation system before.Lastly,the Star Sensor navigation error caused by the vehicle's rocking and the weather can be obtained and corrected by the trained BPNN.The coarse alignment method for the travelling surface ship based on the Accelerometer/Star Sensor/DVL is proposed.The specific force along the inertial frame is derived from the acceleration sensed by accelerometers,and the information characteristics of the specific force along the inertial frame are discussed.The analyzed results show that the constant and periodical information is included in the transformation specific force along the inertial frame.Therefore,Butterworth low-pass filter is used to extract the constant information in order to calculate the attitude of the vehicle.In order to avoid the integrated navigation accuracy is influenced by the accuracy of the single sensor's navigation information increases or failure,the federated filter based on the adaptive information allocation factor,is introduced.And the adaptive information allocation factor is derived by the relationship between the prediction covariance matrix and the updating covariance matrix.Therefore,the influenced of the reference navigation information accuracy from the Star Sensor and DVL on the integrated system is avoided,and the integrated navigation scheme is improved.