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Model-Free Trajectory Optimisation for Unmanned Aircraft Serving as Data Ferries for Widespread Sensors
Computer Science, University of Colorado at Boulder, Boulder, CO 80309, USA
Electrical, Computer, and Energy Engineering, University of Colorado at Boulder, Boulder, CO 80309, USA
* Author to whom correspondence should be addressed.
Received: 21 July 2012; in revised form: 18 September 2012 / Accepted: 18 September 2012 / Published: 9 October 2012
Abstract: Given multiple widespread stationary data sources such as ground-based sensors, an unmanned aircraft can fly over the sensors and gather the data via a wireless link. Performance criteria for such a network may incorporate costs such as trajectory length for the aircraft or the energy required by the sensors for radio transmission. Planning is hampered by the complex vehicle and communication dynamics and by uncertainty in the locations of sensors, so we develop a technique based on model-free learning. We present a stochastic optimisation method that allows the data-ferrying aircraft to optimise data collection trajectories through an unknown environment in situ, obviating the need for system identification. We compare two trajectory representations, one that learns near-optimal trajectories at low data requirements but that fails at high requirements, and one that gives up some performance in exchange for a data collection guarantee. With either encoding the ferry is able to learn significantly improved trajectories compared with alternative heuristics. To demonstrate the versatility of the model-free learning approach, we also learn a policy to minimise the radio transmission energy required by the sensor nodes, allowing prolonged network lifetime.
Keywords: data ferries; sensor networks; delay-tolerant networks; trajectory optimisation; reinforcement learning; stochastic approximation; sensor energy conservation
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Pearre, B.; Brown, T.X. Model-Free Trajectory Optimisation for Unmanned Aircraft Serving as Data Ferries for Widespread Sensors. Remote Sens. 2012, 4, 2971-3005.
Pearre B, Brown TX. Model-Free Trajectory Optimisation for Unmanned Aircraft Serving as Data Ferries for Widespread Sensors. Remote Sensing. 2012; 4(10):2971-3005.
Pearre, Ben; Brown, Timothy X. 2012. "Model-Free Trajectory Optimisation for Unmanned Aircraft Serving as Data Ferries for Widespread Sensors." Remote Sens. 4, no. 10: 2971-3005.