Integrated navigation of interferometric radar altimeter-aided terrain referenced navigation and inertial navigation

Abstract

Radar altimeter that has been utilized in classical terrain referenced navigation(TRN) has a defect that it cannot reflect the roughness of terrain which is a critical factor that determines the performance of TRN. Therefore, interferometric radar altimeter(IRA)-aided TRN has been suggested in the sense that it possesses much information of the closest terrain point with improved accuracy. Many of the researches, however, utilize the existing framework of classical TRN to adapt the measurements of IRA by nonlinearly combining them. Therefore, the performance of IRA-aided TRN remains stagnated. This paper proposes a new measurement model of an IRA, and provides numerical results that shows improved position accuracy of an aircraft. Furthermore, tight fusion of IRA-aided TRN with inertial navigation system(INS) is proposed. Rather than combining the separately acquired navigation solutions from INS and IRA-aided TRN afterward, this paper fuses both solutions jointly through one master filter. Particle filter is used to embrace high nonlinearity that exists in IRA’s measurement when estimating position of an aircraft. Rao-Blackwellized particle filter is used to fully utilize linear substructure inherent IRA measurement, while accommodating nonlinearity of entire system when TRN is fused with INS. Numerical result shows that it is possible to retain accurate 3D navigation solution without aids of barometric altimeter and global navigation satellite system.