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[Abstract] The USC Information Sciences Institute and Astronautics and Space Technology Division LEAPFROG project was conceived as a solution to the challenges associated with the development and testing of lunar landing technologies. This unmanned vehicle borrowed from the Apollo-era Lunar Landing Research Vehicle and more recent Kinetic Kill Vehicles to provide a low cost reusable test bed for technology development. LEAPFROG was envisioned as a three month paper-to-flight project to create a generationzero proof of concept vehicle using COTS components to maintain the lowest possible project cost. The lander was designed around the initial requirements for repeatable three minute untethered flights, COTS component construction, and to be completely built and integrated by students. Secondary requirements included a return to flight time of 15 minutes, translation capability in the X and Y axes, and wireless safe-mode shutdown. LEAPFROG was developed to follow Apollo-like landing approaches using a kerosenepowered JetCat P200 jet engine for hover and descent flight. Lateral and rotational control was provided through 12 cold-gas thrusters. The flight software was developed in Matlab/Simulink. In the event of a flight profile hold, the vehicle could enter a hover mode and maintain a fixed position. A rapid landing safe mode could be triggered from either the ground control unit or an internal flight error loop. Aside from the launch command, the landing safe mode was the only other signal sent to the vehicle, making it completely autonomous. The software was integrated on a Rabbit 3400 microprocessor module interfaced to a very small proprietary INS system which provided GPS, 3-axis accelerometer inputs, and WiFi communications access. The inertial navigation system also contained three Analog Devices MEMS gyros. The system was powered by a combination of LiPolymer and Ni-Cad rechargeable batteries. The vehicle structure was composed of a composite fiberglass laminated foam core bulkhead and four carbon fiber legs. To mitigate impact stresses, crushable landing pads were utilized. This design was inspired by the Surveyor spacecraft, and, aside from the fuel and control gas, the pads were the only nonreusable components on the vehicle. LEAPFROG weighed 20.41 kg (45 pounds), and was 0.76 meters (30 inches) in diameter. This proof of concept was designed as a stepping stone to a generation-one prototype test bed with increased flight time and payload capacity. Though it will maintain many of the core components of the generation-zero vehicle, its |
