A spherical constant velocity model for target tracking in three dimensions

We present a new set of Kalman filters that posit near constant-velocity motion in spherical coordinates. Since the filter operates in spherical coordinates, a new nonlinear dynamic motion equation is developed along with a linear observation equation. Specific filter implementations include a spherical extended Kalman filter (KF) and a spherical sigma point Kalman filter structure that includes the unscented, spherical simplex and Gauss-Hermite KF's. The performance of the filters are demonstrated for a target that maneuvers in three dimensions and compared to similar results from their Cartesian filter counterparts.