Abstract:
A method for real time in-flight prediction of the ground impact point of an indirect fire projectile is investigated. The method investigated is comprised of a combination of an impact point predictor and an extended Kalman filter state estimator based on modified linear theory. The modified linear theory model is formed through a re-derivation of projectile linear theory with a less restrictive set of assumptions. Performance documentation for the modified linear theory model is provided in the form of typical results for both a short range trajectory of a direct fire fin stabilized projectile and a long range trajectory for an indirect fire spin stabilized round. The extended Kalman filter blends sensor data with an internal modified linear theory model to obtain an estimate of the projectile state. Three sensor configurations are explored, each assuming that sensor measurements are available at discrete times during flight. Results generated from a previously validated non-linear six degree of freedom projectile model and simulated noisy sensor readings indicate the technique is capable of predicting ground impact to within 15 meters at the apex of the trajectory when full state feedback is available.
