NovAtel's Annual Journal of GNSS Technology Solutions and Innovation

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little bird FROM Boeing's Little Bird UAV For several years now the Boeing Unmanned Little Bird program has been examining various methods for executing a vertical takeoff and landing of an unmanned aerial system on to a moving vessel for launch and recovery operations. An engineering team describes the development and testing of a GNSS/inertial system that uses relative navigation techniques to do this successfully. FLEDGLING THE BOEING COMPANY INITIATED THE UNMANNED LITTLE BIRD (ULB) PROGRAM in the fall of 2003 to create a developmental platform for an optionally manned, vertical takeoff and landing (VTOL) unmanned aerial vehicle (UAV). This article describes a recent Boeing sponsored flight test effort to integrate and demonstrate a novel and highly precise VTOL UAV navigation system for use in a maritime environment. The result chronicled here portrays a method employing integrated GNSS and inertial navigation capabilities to autonomously guide a VTOL UAV—in this case, a Boeing H-6U helicopter—to a predetermined precision landing anywhere on a ship deck, regardless of deck dimensions. The purpose of this system development was to create a tool suitable for evaluating the performance of a non-GNSS—based terminal-area navigation system on a moving vessel. Moving Baseline Relative Navigation The conventional way to achieve precise positioning with GNSS is to transmit code and carrier phase corrections from a stationary base station at a known coordinate to the rover receiver. When landing a helicopter onto a ship, a number of difficulties with the conventional approach to precise GNSS positioning arise. Due to the mobility of the ship and its ability to operate in remote locations, establishing a stationary base station becomes highly impractical if not impossible. Even if it were possible, the varying dynamics of the ship and helicopter can result in highly variable constellations with respect to the base station. Moreover, substantial changes in satellite constellation can weaken the geometric quality of the available observations to the point of losing the GNSS solution altogether. TO FLIGHT For more Solutions visit http:/ / 2013 velocity 15

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