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Construction
The small scale UAV we self-constructed is based on a off-the-shelf helicopter model. Raptor 90SE is selected for its outstanding flight performance, agility, large payload and light weight. The custom onboard computer system, which is integrated by key components such as PC-104 computer stack, IMU, wireless modem, servo controller, peripheral analog sensors and battery pack, is mounted under the bottom of helicopter through anti-vibration isolators. Data collected from various sensors and IMU are sent to PC-104 computer to process, and based on the identified model, control signal are sent out to servo controller to realize automatic control. All necessary data are transferred to ground station computer through wireless modem for user monitoring and analysisˇ |
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Software Architecture
The onboard software system runs on real-time system QNX Neutrino 6.21. Structure of multiple threads are employed to run various onboard tasks including ¨C inertial measurement (including GPS), data acquisition, automatic control, servo driving, communication with ground station, and data logging. Tasks are scheduled to run periodically every 20ms. Time cost for hardware and software is designed.
Ground station software runs on Windows XP Professional. The software employs a framework of two layers ¨C background data transferring and foreground data visualization. Multiple views are developed to visualize real-time data transferred from onboard system ˇ
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Model Identification
A systemic identification procedure is developed to identify the MIMO model for our designed UAV helicopter under different flight conditions. Generally speaking, the procedure could be divided into the following steps. Firstly high quality in-flight data is collected in special issued flight tests. Secondly flight data is loaded in MATLAB environment and suitable dataset is selected for further identification purpose. Thirdly the structure-predefined model is used and unknown parameters are identified through specific identification methodology. Lastly some ˇ°freshˇ± data is used to verify the feasibility of identified model. Corresponding toolkit with graphical interface will be developed alsoˇ |
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Development of 3D Monitoring
A 3D graphical interface is developed to realistically display the motion of the helicopter. In first stage, 3D models of the helicopter and environment are built using 3ds max. The models of helicopter and environment are stored in 3ds files. In second stage, software programs are developed to draw models and manipulate position and attitude of them. Models are loaded as collection of vertices and polygons with textures attached to them. OpenGL are used to draw 3D models. Helicopter and environment are applied with different geometric transformations ˇ
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