A Regional Alternative Navigation Using the High Altitude Long Endurance UAVs

Abstract

Global Navigation Satellite Systems (GNSS) – GPS, QZSS, BEIDOU and GLONASS – is operating widely in civil and military area and many countries want to have their own navigation system due to its various application fields. GNSS signals, however, can be easily interfered because its signal is too weak. Thus, a sort of backup or alternative system is needed in order that the navigation performance is assured to a certain degree in case of GNSS jamming. In order to suggest a series of backup or alternative system of regional navigation, in this paper, a high altitude long endurance unmanned aerial vehicle (HALE UAV) with pseudolites using inverted GPS and transceiver system was introduced. Inverted GPS system is a device to determine the position of the HALE UAV using the pseudolite signals from UAVs and the known ground stations position, and transceiver system is to determine the location of the UAV using bidirectional range measurements between UAVs and UAVs or between UAVs and ground stations by canceling the clock offset via a double-differencing method. The positioning errors of the regional navigation system using HALE UAV with inverted GPS or transceivers concepts were simulated and the position errors of HALE UAV using the measurements from the other airborne and the ground stations were estimated, and user position errors based on the position error of HALE UAV and general pseudorange error were calculated . In our simulation, the simple flight dynamics of HALE UAV, stratosphere environment such as wind information for the reality were considered, and the performance of regional alternative navigation during 24 hours was simulated. Then a variety of case: six HALE UAVs on six ground stations, six HALE UAVs far away from six ground stations and ten HALE UAVs on six ground stations were conducted in simulations. As a simple result, six HALE UAVs on six ground stations enable users to have the position error of approx. 10~15m on average within a radius 150km at the HALE UAV altitude of 18km. In case of ten HALE UAVs, the improvement of the alternative navigation performance was checked. The result of this paper may contribute to the independent backup or alternative navigation system with HALE UAVs and pseudolites under the situation of unavailable GNSS.