Abstract
The increasing use of Unmanned Aerial Vehicles (UAVs) in safety-critical missions in both civilian and military areas demands accurate and reliable navigation, where one of the key sources of navigation information is presented by Global Navigation Satellite Systems (GNSS). In challenging conditions, for example, in urban areas, the accuracy of GNSS-based navigation may degrade significantly due to user-satellite geometry and obscuration issues without being noticed by the user. Therefore, considering the essentially dynamic rate of change in this type of environment, integrity monitoring is of critical importance for understanding the level of trust we have in positioning and timing data. In this paper, the dilution of precision (DOP) coefficients under nominal and challenging conditions were investigated for the purpose of integrity monitoring in urban environments. By analyzing positioning information in a simulated urban environment using a software-based GNSS receiver, the integrity monitoring approach based on joint consideration of GNSS observables and environmental parameters has been proposed. It was shown that DOP coefficients, when considered together with a number of visible satellites and cut-off elevations specific to the urban environment carry valuable integrity information that is difficult to get using existing integrity monitoring approaches. This has allowed generating indirect integrity measures based on cut-off elevation and satellite visibility that can be used for UAV path planning and guidance in urban environments.
Highlights
Due to the growing interest in the use of Unmanned Aerial Vehicles (UAV), research in the Guidance, Navigation and Control (GNC) area has become increasingly important
The 95th percentile of the horizontal error is within alert limits when HDOP ≤ 3.13, and for the vertical error, this is true when Vertical DOP (VDOP) ≤ 5.13
Due to the dependence of Global Navigation Satellite Systems (GNSS) positioning integrity on satellite visibility and environmental constraints, joint use of dilution of precision (DOP) coefficients, number of visible satellites and cut-off elevation in urban environments was investigated in this study for integrity monitoring purposes
Summary
Due to the growing interest in the use of Unmanned Aerial Vehicles (UAV), research in the Guidance, Navigation and Control (GNC) area has become increasingly important. Navigation is one of the key components of GNC, and it carries a number of important requirements to UAV performance that play a key role in ensuring mission safety and success. Accuracy: The degree of conformance between the estimated or measured position and/or velocity of a platform at a given time and its true position or velocity. Continuity: The continuity necessary position within the defined airspace) to perform its function without necessary totomaintain maintainaircraft aircraft position within the defined airspace) to perform its function interruption during the intended operation. According to International Civil Aviation Organization (ICAO) Position, Navigation and Timing (PNT) solutions are characterized by accuracy, integrity, continuity and availability within the Performance Based Navigation (PBN) concept [1,2] as follows:
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