Extension to modified polar coordinates and applications with passive measurements
Sivasubramanya Nadar Balakrishnan · Journal of Guidance Control and Dynamics · 1989
A practically successful method to achieve better estimation results for target tracking with passive measurements has been obtained through the use of a set of modified polar coordinates. This state space consists of the reciprocal of the range, the range rate over range, the range acceleration over range, the bearing angle, the bearing-angle rate, and the bearing acceleration, in two dimensions. The elevation angle, its rate, and its acceleration are added to the state space in three dimensions. The performance of this modified polar coordinate filter is superior to that of the widely used rectangular Cartesian coordinate-based extended Kalman filter. Numerical results are obtained by processing the observations made on a single reference trajectory in two dimensions and from a target-intercept problem in three dimensions. Error histories of the range under nominal and off-nominal conditions are presented. Also, the conditions for the observability using passive measurements have been extended to cases where target acceleration is an element of the state space.