Research On Attitude Determination Of Guided Projectile Based On Ballistic Model

With the progress and development of novel sensing technology,the future trends of weaponry is to develop the accurate guidance of conventional artillery ammo.To achieve precise trajectory control and correction for the sake of the trajectory error dispersion reduction,the flight attitude of guided projectiles should be measured accurately.Based on the trajectory model,this pap er mainly studies the low-cost geomagnetic-inertial strapdown integrated attitude measurement system,and investigates nonlinear filtering problem.Firstly,by properly selecting coordinate system,the kinematic and dynamic analysis of the guided projectile is carried out through applying the theory of exterior ballistics.A six degree of freedom rigid body ballistic equation is established to describe the dynamic of the interested projectile.A numerical simulation is provided to analyze the ballistic characteristics and to lay the foundation for the subsequent ballistic simulation and the attitude filtering.Aiming at the low cost attitude measurement of guided projectiles,an attitude measurement scheme combining magnetic sensors and accelerometers is pro posed.Based on the theory of the earth's magnetic field,the magnetic field elements and mathematical model are analyzed,and the principle and application of the geomagnetic sensors are briefly introduced.To estimate attitude,the algorithm determining initial value of filter using magnetic sensor measurement is analyzed,and the measurement equation for nonlinear attitude filtering problem is derived.Based on the ideal trajectory,a nonlinear filtering state model and a trajectory filtering equation are established to describe the motion of attitude angle of projectiles and the variation of trajectory parameters.In the all ballistic numerical simulation,the EKF,UKF and MKF methods are respectively used to analyze the body attitude angle and the ballistic filtering value.The results suggest that the filtering accuracy of UKF and MKF methods can meet the requirements of attitude measurement of guided projectiles.Compared with the former methods,MKF achieves a balance between filtering accuracy and computational efficiency,which implies that the MKF is more suitable for engineering design of guided projectiles.This paper simulates the robustness of the magnetic navigation system subject to parameter perturbation,and the attitude calculation algorith m under wind disturbance.In conclusion of this paper,the navigation dead zone problem of geomagnetic attitude determination is discussed and engineering solution is given accordingly.