Velocity

2013

NovAtel's Annual Journal of GNSS Technology Solutions and Innovation

Issue link: http://velocitymagazine.epubxp.com/i/164724

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little bird Maritime flight tests during the summer of 2012 demonstrated the accuracy of the navigation solution, as well as the integration of the navigation solution with the automated flight control system on the Boeing H-6U Unmanned Little Bird. A total of 16 fully autonomous landings and 13 fully autonomous takeoff/departures comprised this latest effort, with the flight crew closely monitoring the controls and the aircraft position when the aircraft was in close proximity to the deck. In all, seven sequential days were required to accomplish the deck qualifications of two Boeing test pilots, integrate and debug all systems and software, and carry out maritime terminal operations until the operation became routine. These efforts demonstrated the value of the Unmanned Little Bird program's optionally manned system architecture. For more Solutions visit http:/ /www.novatel.com 0.35 Position Displacement (m) Conclusion FIGURe 1: Trajectories of Shadow Allure (green) and Little Bird (red) during automated landing test. 0.3 0.25 0.2 0.15 0.1 0.05 0 -0.05 3.1635 3.1636 3.1637 3.1638 3.1639 3.164 × 105 GPS Time (s) FIGURe 2: Real-time to post-processed relative vector differences. 300 DGPS Altitude (ft) Radar Alt (ft) vertical error of the lever arm. In post-processing, the new lever arm was used and the average relative position values of the helicopter on the landing pad were -0.383m North, -0.298 East, and 0.771 Up, which agrees much better to the known helicopter belly height. Figure 2 shows the difference between the real-time and post-processed relative position solutions as the helicopter was landed. Recall that the real-time solution shows about 35 centimetres of height error due to the lever arm used in real-time. The nature of the test program did not allow for extensive tuning of the automated flight control system to respond in an optimal fashion to the navigation data input. Nevertheless, the results from the initial test program were impressive. Table 1 presents the difference between the H-6U position at 10 feet above the helipad and after landings to the helipad during one sortie. The radar altimeter output compared very favorably with the RTK solution, as shown in Figure 3. 200 100 0 2900 3000 3100 Time (s) 3200 3300 FIGURe 3: Radar altimeter vertical data (green) compared to GNSS/INS vertical data (red). 2013 velocity 19

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