Study On Line Of Sight Rate Estimation For Strap-down Seeker

As the main measuring instrument of homing guidance system,the seeker is one of the most important components to generate guidance commands,which will make a great difference to the accuracy.In order to meet low-cost,high-precision and miniaturizing need of the seeker in contemporary war,strap-down stabilization of the seeker sight becomes into the leading research and development trend in the recent decades.At the beginning,it's summarized and analyzed that the present condition and development trends of strap-down seekers and guided bombs.After expounding the constitutions,operating principle and working condition of the seekers,the typical mathematical model is established according to the transfer functions of all elements of the seeker.The comparison tells that the strap-down stabilization has a great advantage over the traditional ones in the guidance systems.Considering the special kinematics of strap-down seeker,the body LOS coordinate system is introduced,based on which the decoupling algorithm of LOS angles rates is brought forth that after combining the attitude angles with body LOS angles the LOS angles rates are gained by differentiating the result.In order to show the stochastic noise of strap-down seeker vividly,the linear combination noise of Gaussian noise and the gamma distribution noise is adopted.Compared with some derivative Kalman filters,the Unscented Kalman Filter(UKF)has an advantage in dealing with the nonlinear model.The filtering estimation model of LOS angle rates of strap-down based on UKF is derived,after introducing the Unscented Transformation to the state and measurement equation of the extracting LOS angle rates model.The simulation results using MATLAB indicate that UKF estimation algorithm is better than the EKF one in extracting LOS angle rates.The application and structure of strap-down seeker in guided bomb flight arestudied in C environment.The simulation result indicates that the guided missile's attacking performance improves a lot with the help of strap-down seeker's LOS angle rates applying in proportional navigation law.