Showing papers by "Patrick Henkel published in 2020"

Precise 6D RTK Positioning System for UAV-based Near-Field Antenna Measurements

Abstract: Near-field antenna measurements with an Unmanned Aerial Vehicle (UAV) require an accurate 3D position and 3D attitude information. In this paper, we estimate the position and velocity of the UAV, the quaternion that describes its attitude, the carrier phase integer ambiguities related to both the attitude and position, and the accelerometer bias with a Kalman filter. The raw measurements were obtained from the ANavS Multi-Sensor RTK module with its 3 Multi-frequency, Multi-GNSS receivers and a MEMS-based Inertial Measurement Unit (IMU). We used the UAV of AeroXess to validate our method and achieved a centimeter-level positioning accuracy in both static and kinematic conditions.

“PREParE SHIPS” for Automated Ship Passages by Modern Decision Support Tools by Exchanging Future Positions

Abstract: Misunderstanding the intentions of other vessels is one of the most common causes of ship collisions today. Such misunderstandings are particularly dangerous during navigation in restricted areas, such as fairways, port areas, and inland water ways, and may be exacerbated with the introduction of unmanned vessels. To ensure safe operations, the understanding of the intentions and future positions of manned and unmanned vessels, the PREParE SHIPS project is creating a system capable of determining a ship's position with high accuracy, predicting its future positions, and communicating the current and future positions. The positioning sub-system combines the signals of Galileo and EGNOS, EGNSS and SBAS respectively, with land based RTK corrections, providing a positioning accuracy of centimetres. Furthermore, by taking advantage of Galileo's authentication features, the positioning system provides enhanced security measures against spoofing attacks. The prediction sub-system will use a ship dynamic model and machine learning to predict the future positions of the ship and improve said predictions with time, while the communication sub-system will broadcast the prediction through VDES ship2ship and ship2shore. PREParE SHIPS will improve the navigation and handling of ships, through high accuracy positioning and dynamic predictions, as well as reduce the risk of ship collisions, through the communication of present and predicted future positions. PREParE SHIPS is expected to increase safety and efficiency significantly and will be the base of future autonomous operations and standardisations.

Precise Point Positioning for Next-Generation GNSS

Abstract: Precise Point Positioning (PPP) provides accurate absolute position information without the direct need of measurements from a reference station at the user The current challenge of GPS L1/L2-based PPP is its long convergence time of more than 20 minutes being caused by the need to estimate atmospheric parameters, and the relatively large code noise and multipath errors There are two options to reduce the convergence time of PPP: First, the Galileo wideband signals on E5 and E6 have a much lower code noise than current GPS L1 and L2 pseudoranges Second, the satellite positions and satellite-related biases can be determined much faster and more accurately with optical inter-satellite links supporting ranging, time-transfer and intra-system communication In this paper, we consider both options A joint estimation of the receiver position, receiver clock offset, tropospheric zenith delay, ionospheric slant delays and carrier phase ambiguities is performed with a Kalman filter Orbital errors and pseudo range multipath are also taken into account The float carrier phase ambiguity estimates are mapped to integers using the famous Least-Squares Ambiguity Decorrelation Adjustment (LAMBDA) method The simulation results show that an ambiguity fixing and, thereby, a highly-accurate PPP solution, can be achieved consistently within a few epochs This is a quite substantial benefit and could make PPP attractive for numerous applications