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X-Pilot: Autopilot Solutions C. Edwards, J. Lasseigne, W. Overstreet, B. Penland Project Description: The X-Pilot: Autopilot Solutions project is developing a complete autopilot system (hardware in the air vehicle and groundstation software) that can be easily integrated into fixed-wing airplanes and is user programmable while in flight. The autopilot hardware is based on a Crossbow hardware platform and includes a custom-built AGL (Above-Ground-Level) sensor. The software includes the associated autopilot software along with the groundstation software. X-Pilot Components: •Crossbow MNav sensor platform •Crossbow Stargate Linux computer •Standard 802.11 wireless card •Custom ultrasonic AGL sensor •6.0 Volt nickel metal hydride battery to power MNav and Stargate •9.0 Volt alkaline battery to power AGL sensor •Software components for the autopilot and the groundstation (both written in C++) •Hammond 1590T aluminum electrical enclosure Design Constraints and Implementation: Testing: Testing for all X-pilot components occurs in three stages. First, the component is tested with a ground software simulation. Second, the component is tested with a ground hardware simulation. Finally the component is flight tested. Current Challenges: •GPS connection and functionality •Converting AGL to autopilot connection from serial to USB •Ground simulation tests •Flight testing Areas for Improvement (second semester goals): Team X-pilot’s major second semester goal is to get the GPS unit functioning with the autopilot system. We will then shift our focus to extensive flight testing, including in-air testing of the AGL which will be on a PCB board by this time. After insuring that the system functions properly in the air and still meets all of the technical constraints, we will begin looking at adding additional features. Some of these features might include auto-takeoff, auto- X-Pilot Features: •Costs under $2500 •Utilizes open source code for easy user modification •Capable of autonomous flight by waypoint navigation •Users can integrate custom hardware •Equipped with an AGL for use with low level flight •For use with fixed-wing or flying- wing aircraft X-pilot with labeled components Technical Constraint Description Implementation Waypoint Navigation Accuracy Waypoint navigation must be accurate to within ±10 meters. Achieved by using gains and verifying with flight log files. Low Altitude Accuracy X-pilot must be capable of accurate readings at low altitudes (±0.08 m). Low altitude accuracy achieved through an AGL using ultrasonic range finders. Real-Time The autopilot must have an update rate between 1 Hz and 50 Hz. By using threading, the autopilot achieved an update rate of 50 Hz. Control Surfaces X-Pilot must capable of controlled flight for a fixed-wing aircraft. X-pilot is capable of controlling the five control surfaces of a fixed-wing aircraft (two ailerons, an elevator, a rudder, and a throttle). Compatibility The groundstation software must be POSIX and Windows compatible. The groundstation is written in C++ and uses OpenGC. Dynamic Re- tasking X-Pilot must be capable of dynamic re- tasking at all times. The autopilot and groundstation communicate over wireless at all times so new waypoints can be uploaded at any time. Practical Constraint Description Implementation Cost Parts for one AGL must cost less than $200. By using ultrasonic range finders, the AGL price was kept under $200. Failsafe X-Pilot is equipped with an RC manual override. Channel 5 on the RC receiver is used to disable the autopilot mode and act as a manual override. Secure Communications Communication to the autopilot must be secure. Because an 802.11 wireless router is being used, any encryption supported by the router can be implemented. Expandable Design X-Pilot is capable of user upgrades and modifications. All software is open source, therefore the user can easily upgrade or modify the software. Operating Temperatures The system must operate in temperatures of 0-45°C. All hardware used for X- pilot is rated for an operating temperature range of at least 0-45°C. X-pilot groundstation demonstrating waypoint navigation and one possible autopilot application—crop dusting. X-pilot flight testing Left: X-pilot autopilot software Right: Foam plane used for hardware ground testing X-pilot’s Above-Ground-Level (AGL) sensor X-pilot’s groundstation software
