High-precision Positioning and Real-time Data Processing of UAV-Systems


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Available micro-sized Unmanned Aerial Vehicles (UAVs) in the civilian domain currently make use of common GPS receivers and
do not address scenarios where high-precision positioning of the UAV is an inevitable requirement. However, for use cases such as
creating orthophotos using direct georeferencing, an improved positioning needs to be developed. This article analyses the
requirements for integrating Real Time Kinematic positioning into micro-sized UAVs. Additionally, it describes the data processing
and synchronisation of the high-precision position data for a workflow of orthorectification of aerial imagery. Preliminary results are
described for the use case of precision farming.

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High-precision Positioning and Real-time Data Processing of UAV-Systems

  1. 1. High-precision Positioning and Real-time Data Processing of UAV-Systems Matthes Rieke, Theodor Foerster, Jakob Geipel, Torsten Prinz Institute for Geoinformatics – University of MuensterUAV-g 2011 Conference – September 16, 2011 – Zurich, Switzerland http://purl.net/ifgi/copter
  2. 2. Sensor platforms ● Current available UAV systems use common GPS receivers ● Not addressing use cases where high position accuracy is inevitable ● Creating orthophos using Direct Georeferencing2 http://purl.net/ifgi/copter
  3. 3. Approach for improving position accuracy• Micro- or small-sized UAV systems• Improvement using Real Time Kinematic• Prototypical realization using a Microdrones md4-200 • Overview of the used hardware • Conceptual design of data processing software3 http://purl.net/ifgi/copter
  4. 4. Teaser of the used hardware4 http://purl.net/ifgi/copter
  5. 5. Possible use case• Improve/Enable Direct Georeferencing • Currently limited due to several aspects • Exterior orientation (e.g. low-cost GPS/GNSS, IMU) • Alignment of time of image acquisition and positioning  Focus on improving absolute positioning using advanced GNSS techniques + timestamp synchronisation• Stabilize flight trajectory • Decrease the position delta between planned and actual image position5 http://purl.net/ifgi/copter
  6. 6. Improving position accuracy on-the-fly REAL TIME KINEMATIC6 http://purl.net/ifgi/copter
  7. 7. Real Time Kinematic• Specialized form of Differential GNSS• Ground based Augmentation System• Takes phase observations into account for error estimation• Based on correctional signals from national services7 http://purl.net/ifgi/copter
  8. 8. Real Time Kinematic• What do you need?• In general: rather cost-intensive hardware • GNSS receiver + antenna – processing of RTK corrections • Radio modem (e.g. GPRS) to retrieve correction signals • Processing unit for data communication• Payload!8 http://purl.net/ifgi/copter
  9. 9. Real Time Kinematics9 http://purl.net/ifgi/copter
  10. 10. Benefitting from improved positioning DATA PROCESSING10 http://purl.net/ifgi/copter
  11. 11. Software approach ● Software running on groundstation ● Support for different UAV platforms ● Synchronization of multiple data streams to enable real-time measurement capabilities ● Modulized architecture to foster reusability ● Realized using Software Framework11 http://purl.net/ifgi/copter
  12. 12. Framework Approach ● Architecture12 http://purl.net/ifgi/copter
  13. 13. Framework Approach ● Synchronization of sensor streams ● Why synchronize streams? ● Knowledge of exact position at time of image aquisition ● Currently: interpolation mechanism ● Abstract – easily adjustable for application13 http://purl.net/ifgi/copter
  14. 14. Framework Approach ● Basis is description of Plugin Behaviour ● Input/Output phenomena using XML descriptions ● When to determine a position?14 http://purl.net/ifgi/copter
  15. 15. Applying in real-world situations RESULTS AND FUTURE WORK15 http://purl.net/ifgi/copter
  16. 16. Hardware integration • Currently only DGPS receiver used • Future work involves an RTK-enabled L1/L2 GPS/GLONASS receiver • Problem of moved centroid • Hardware optimization • Implementation of Direct Georeferencing workflow • Move to md4-1000 to gain more payload16 http://purl.net/ifgi/copter
  17. 17. Hardware integration17 http://purl.net/ifgi/copter
  18. 18. Use case – precision farming Monitoring Precision workflow farming Push-based communication18 http://purl.net/ifgi/copter
  19. 19. Source Code available at:19 http://purl.net/ifgi/copter
  20. 20. WHAT IS MISSING?20 http://purl.net/ifgi/copter
  21. 21. Thank you for your kind attention! Questions? http://purl.net/ifgi/copter Matthes Rieke – m.rieke@uni-muenster.de21 http://purl.net/ifgi/copter