Bias compensation for improved recursive bearings-only target state estimation

In recursive bearings-only tracking the Cartesian coordinate EKF provides poor convergence and erratic behavior due to the lack of observability of the target range. The EKF formulated in modified polar (MP) coordinates, which decouples the observable and unobservable components of the target state, has been shown to provide improvements in estimation convergence over the Cartesian EKF. A new Cartesian coordinate method is developed which estimates the range bias to compensate the position estimates of the filter. The resulting filter, called the bias compensated Cartesian filter(BCCF) is shown to provide improved velocity estimation and comparable position estimation with the MP method