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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

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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

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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

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Teaser of the used hardware4 http://purl.net/ifgi/copter

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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

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Improving position accuracy on-the-fly REAL TIME KINEMATIC6 http://purl.net/ifgi/copter

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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

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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

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Real Time Kinematics9 http://purl.net/ifgi/copter

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Benefitting from improved positioning DATA PROCESSING10 http://purl.net/ifgi/copter

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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

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Framework Approach ● Architecture12 http://purl.net/ifgi/copter

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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

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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

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Applying in real-world situations RESULTS AND FUTURE WORK15 http://purl.net/ifgi/copter

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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

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Hardware integration17 http://purl.net/ifgi/copter

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Use case – precision farming Monitoring Precision workflow farming Push-based communication18 http://purl.net/ifgi/copter

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Source Code available at:19 http://purl.net/ifgi/copter

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WHAT IS MISSING?20 http://purl.net/ifgi/copter

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Thank you for your kind attention! Questions? http://purl.net/ifgi/copter Matthes Rieke – m.rieke@uni-muenster.de21 http://purl.net/ifgi/copter