Tracking a three-dimensional moving target with distributed passive sensors using extended Kalman filter

A method is proposed for combining the acquired information of several passive sensors in order to obtain two-dimensional information on the elevation and azimuth angles of the target and to estimate the location and velocity of the moving target in a three-dimensional space. In the case of a moving target, several sensors are required to observe the target at the same time if the so-called triangulation measurement is used. Hence, if each sensor carries out measurement asynchronously, the target position cannot be accurately computed, in the proposed system, angular tracking is carried out first at each sensor level of two sensors. After a certain time, the time alignment is carried out for the results of angular tracking. Then, the initial value of the three-dimensional trajectory is computed by combining the angular tracking results. Further, once the initial value is computed, a three-dimensional tracking maintenance process by an extended Kalman filter is initiated at the central level. Every time a new observed value from one of N sensors is obtained, this is used for updating the three-dimensional trajectory. In the present system, a moving target can be tracked even if several sensors carry out observation asynchronously. The effectiveness of the present method is verified by simulation. (C) 2001 Scripta Technica.