Relative heading estimation for target handoff in GPS-denied environments

This paper addresses the problem of target handoff between two fixed wing aircraft that do not have access to GPS. The problem requires estimating the relative pose between the vehicles. We examine the observability of the relative states needed to do the handoff when the relative position vector between the aircraft is measured, as would be the case for a radar or a lidar sensor. We assume that the two aircraft do not exchange their airspeed and turn rate information. Under mild assumptions, we show that the relative heading between the two aircraft is observable. The paper also proposes an estimation algorithm that uses a bank of extended Kalman filters (EKF) to estimate the relative states. Simulation results demonstrate the feasibility of the proposed approach and the advantages of the EKF bank over a single EKF in a high-noise scenario.