Design And Implementation Of Underwater Fiber Strapdown Inertial Measurement Device

Underwater navigation has always been a hot topic in the field of navigation,because underwater navigation and radio signal attenuation make the navigation methods available underwater very limited.Inertial navigation(referred to as "inertial navigation")has become a more practical navigation method in underwater navigation because of its independence,autonomy,high precision and small size.However,the inertia error will accumulate over time,so it is often used.Navigation is performed by a combination of inertial navigation and GPS/Doppler log.Based on the analysis of the current development of underwater navigation at home and abroad,this paper designs an underwater navigation device consisting of Strapdown Inertial Navigation/Doppler Logger,in which the inertial navigation adopts the strapdown method,including three orthogonal The fiber optic gyroscope and three orthogonal quartz accelerometers measure the angular velocity and acceleration of the carrier motion;the navigation computer with DSP and FPGA architecture is responsible for the navigation solver function;and the Doppler log gauge measures the aircraft to the ground.Or the speed of the water,and sent to the navigation computer,and finally through the information fusion,to achieve accurate positioning and navigation.The main research content of the thesis:(1)Complete the overall design of the underwater fiber strapdown inertial measurement device.For the functions that the inertial measurement device needs to implement,the hardware design,software logic and system structure of the device are designed overall.At the same time,the key devices such as fiber optic gyroscope,accelerometer and Doppler log are introduced and selected..(2)The core algorithm of strapdown inertial measurement device is studied.Starting from the principle of strapdown inertial navigation("INS")and Doppler log("DVL"),the calculation model of speed,position and attitude of strapdown inertial navigation and Doppler log are derived.Based on the velocity measurement equation,and based on this,the Kalman filter is used to estimate the error of the two,and the feedback correction of the device is realized,thereby outputting accurate navigation parameters.(3)Complete hardware and software engineering in the device.The DSP and FPGA form the hardware core circuit,and combine the sampling circuit,the power supply module,the communication module and other peripheral circuits to realize the hardware platform construction;according to the built hardware platform,the software engineering design in the device is completed,mainly including the FPGA software program design and The DSP software program is designed to realize the data acquisition,navigation solution and external communication functions of the device.(4)The test verification of the underwater fiber strapdown inertial measurement device is completed.Firstly,the fiber gyro and accelerometer are modeled and compensated,including calibration test and temperature error compensation.Then the performance,reliability and stability of the device are verified by indoor static test and underwater positioning test.The test results show that the underwater fiber strapdown inertial measurement device is stable and reliable,its heading accuracy is better than 0.1° sec?(? is the local latitude),the attitude accuracy is better than 0.05°,and the underwater positioning accuracy is better than 0.2% ×L(L is the sailing mileage).),with practical engineering application value.