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Rapid Initialization and Filter Convergence for Electro-optic / Infrared Sensor Based Precision Ship-Relative Navigation for Automated Ship Landing


Carrier based fixed wing aircraft need accurate, high rate, and high integrity precision ship-relative navigation (PS-RN) to conduct safe and efficient automated landings. This SBIR is focused on capability that is not dependent on Radio Frequency (RF) emissions or Global Positioning System (GPS) in order to reduce vulnerability to interference. The PS-RN solution must initialize very quickly because of the relatively high closure rates (approx. 120 knots). Electro-Optical/Infrared (EO/IR) aircraft mounted cameras are attractive sensors due to low cost and size, but do not directly measure range and angle, so these calculations must be reliably extracted from the imagery at a high data rate (approx. 30 Hz). They must initialize quickly (10 seconds or less) when imagery becomes usable as the aircraft approaches the ship, even with obscured visibility and deck motion. Current image detection, tracking, and template matching require too much time (over 1 minute) to be usable for a jet aircraft approach in reduced visibility. Convergence rate of linearized filters is not adequate for the required precision of relative navigation; non-linear filters may provide a workable approach. For this SBIR effort, the sensors to be used are aircraft mounted electro-optic and/or infrared cameras, with optional use of ship mounted light or beacon sources. The navigation scenario begins at 4 nautical miles (NMI), with the aircraft at 1200 feet Mean Sea Level (MSL), and within 10 degrees of the landing area centerline. The aircraft inertial measurement unit (IMU) can be used. Ship location is known within 1/2 NMI, course and speed are known within 10 degrees and 5 knots. The ship must be detected and tracking begin rapidly when it enters the sensor field of view; the initialization goal is 10 seconds. The camera system, including lenses, must be small (approx. 200 cubic inches) and able to withstand the electromagnetic interference, shock, and vibration environment of a carrier landing. Only two fixed focal lengths can be used for the entire approach. Computer processing must be done on 1 or 2 cards added to an existing mission computer. Aircraft pose estimate must be accurate within 0.20 degree in azimuth and elevation, and range within 4%. It must be a high integrity solution with sufficient accuracy and continuity (in concert with the IMU) suitable for aircraft control. Ship motions corresponding to sea state 4 must be identified. The lights or beacons must be suitable for installation on the deck, hull, catwalk, or other structural location on an aircraft carrier. PHASE I: Determine feasibility for the development of rapidly initializing detection, tracking and relative pose estimation processes that could be used to provide navigation inputs to the flight control system of a carrier based fixed wing aircraft for landing on an aircraft carrier. Develop a system concept for this purpose and report on the results. PHASE II: Based on Phase I effort, develop and demonstrate sensor processing using available sensor(s) for rapid-initialization PS-RN real-time capability, in simulation, in full range of lighting conditions, from full sun to overcast moonless night, with sea state 4 deck motion. Determine through simulation maximum range capability in fog and rain, and determine the heaviest fog and rain that can exist and still allow accurate navigation to begin at no less than ¾ nautical mile. Collect imagery data during flight approaches and landings in day and dark night conditions using low cost surrogate aircraft and a land based facility. Use these imagery data to demonstrate rapid-initializing real time PS-RN in the laboratory. Conduct an open loop demonstration of real time PS-RN capability in flight. Update the models and software for delivery to the Navy simulation laboratory. PHASE III: From the results of Phase II, design and fabricate a processing system using available sensors which can be carried by an F/A-18 aircraft. The Navy will gather flight test imagery using this system in a separately funded flight test effort. Using the data from this flight test, demonstrate precision ship-relative navigation capability in the laboratory. Develop a preliminary design for an integrated sensor and processing system to be installed on an aircraft carrier and a selected Navy carrier aircraft for operational use.

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