This paper considers the subject of straight-line target tracking for unmanned surface vehicles (USVs). Target-tracking represents motion control scenarios where no information about the target behavior is known in advance, i.e., the path that the target traverses is not defined apriori. Specifically, this work presents the design of a motion control system which enables an underactuated USV to track a target that moves in a straight line at high speed. The motion control system employs a guidance principle originally developed for interceptor missiles, as well as a novel velocity controller inspired by maneuverability and agility concepts found in fighter aircraft literature. The performance of the suggested design is illustrated through full-scale USV experiments in the Trondheimsfjord.

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Abstract-This paper describes recent experiences with operating an unmanned aerial vehicle (UAV) in a coastal and maritime environment beyond line of sight (BLOS) in controlled airspace (class D) where separation from other air traffic is provided by the Air Traffic Control (ATC). The UAV operation followed normal ATC procedures with two-way VHF communication between the UAS Operator and ATC in order to provide separation vertically and horizontally by operation within pre-defined areas according to specific operational procedures made by ATC. Tests were conducted using direct 2.4 GHz radio and GPRS mobile network control links at a distance up to 20 km from the ground control station when operating at 1500 ft altitude. A new low-weight and small size experimental phased-array antenna providing a digital high capacity payload data link was tested and found to give stable real-time HD video at a distance of 50 km under line of sight conditions at 2500 ft altitude.Index Terms-Beyond line of sight; unmanned aerial vehicle; remotely piloted aircraft systems; air traffic control; phased array antenna; digital data link.