Integrated Navigation of Interferometric Radar Altimeter-aided Terrain Referenced Navigation and Inertial Navigation

Abstract

This paper proposes a method of utilizing measurement of interferometric radar altimeter (IRA) into integration of inertial navigation and terrain referenced navigation (TRN). While conventional TRN is supported by radar altimeter that measures vertical channel terrain clearance and estimates horizontal position, proposed method can estimate 3 dimensional navigational states of an unmanned air vehicles (UAV) by utilizing inertial navigation system (INS) in accordance with IRA-aided TRN. Rather than combining the output of TRN with INS in a separated form, integrated navigation that fuses the two in a tightly coupled manner is suggested. To deal with highly nonlinear characteristics of measurement of IRA, particle filter is utilized. Particularly, Rao-Blackwellized particle filter (RBPF) that benefits from state space domain system structure is applicable. This paper aims at step-wise linearization procedure of IRA's measurement so that the system can take advantage of linear substructure. Numerical simulation was conducted under certain condition, and results show that proposed method can estimate UAV's 3-dimension navigational state accurately even when inertial measurement units (IMU) and IRA are the only supporting sensors. Keywords-terrain referenced navigation, interferometric radar altimeter, integrated navigation, inertial navigation system, rao-blackwellized particle filter.