Research On Algorithm And Devices Of Missile-borne Strapdown Inertial Navigation

Missile attitude measurement plays a very important role in the development process of the precision guided munitions. Traditional strapdown inertial navigation technology uses linear accelerometer and inertial gyro to measure acceleration and angular velocity of the missile to calculate its attitude information. However, the gyro can't bear the shock of large linear acceleration and angular acceleration, and inertial device itself exist measurement error which will accumulate with time and form accumulated error finally, thus the application of SINS on the high dynamic missile is limited. This thesis aims at the characteristics of high dynamic and complex missile attitude measurement environment, and considering the advantage of magnetoresistive sensor, for example high overload resistance and low power consumption, combines the inertial measurement devices with magnetoresistive sensor to measure the missile's attitude, so as to improve the performence of missile attitude measurement system in high dynamic environment.Base on the traditional SINS algorithm, this thesis increases the sampling points in the calculation of the rotation vector, and divides the sampling points into three groups for trapezoidal and Simpson integration, so that each insert node is reused to reduce errors caused by the angle increment calculation, and optimize the three sub-sample equivalent rotation vector algorithm. The angle between the z-axis of missile body coordinate system with geomagnetic component in the projectile cross section and the angle between the z-axis of missile axis coordinate system with geomagnetic component in the projectile cross section are calculated by using magnetoresistive sensor. Then the missile's roll angle can be calculated by using the position relationship between the two angles.According to the requirements of onboard measurement environment, missile attitude measurement system based on inertial measurement devices and magnetoresistive sensor is designed, and gyroscopes, accelerometers, magnetoresistive sensors and core processing chip are selected. Data storage circuit, data transmission circuit and other key circuits are designed, and the operating principles of circuits are described.Data from the SINS algorithm attitude values and the magnetoresistive sensor attitude values are fused by using the weighted average algorithm based on weight distribution of minimum variance estimation right value distribution method, so as to improve the attitude measurement accuracy of system.Missile flight path and sensors'output data, which are used to simulative calculation in the designed attitude algorithms, are simulated by using MATLAB simulation. Simulation results show that using inertial measurement devices and magnetoresistive sensor to measure the missile's attitude, after data fusion, the accuracy of the attitude angle measurement can be increased, and a certain degree of measurement accuracy can be achieved.