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Unmanned Aerial Vehicle Research Facility
Unmanned Aerial Vehicle Research Facility
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ItemBank-to-Turn Control for a Small UAV using Backstepping and Parameter Adaptation(Georgia Institute of Technology, 2008-07) Jung, Dongwon ; Tsiotras, PanagiotisIn this research we consider the problem of path following control for a small fixed-wing unmanned aerial vehicle (UAV). Assuming the UAV is equipped with an autopilot for low level control, we adopt a kinematic error model with respect to the moving Serret-Frenet frame attached to a path for tracking controller design. A kinematic path following control law that commands heading rate is presented. Backstepping is applied to derive the roll angle command by taking into account the approximate closed-loop roll dynamics. A parameter adaptation technique is employed to account for the inaccurate time constant of the closed-loop roll dynamics during actual implementation. The path following control algorithm is validated in real-time through a high-fidelity hardware-in-the-loop simulation (HILS) environment showing the applicability of the algorithm on a real system.
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ItemOn-line Path Generation for Small Unmanned Aerial Vehicles using B-Spline Path Templates(Georgia Institute of Technology, 2008) Jung, Dongwon ; Tsiotras, PanagiotisIn this study we investigate the problem of generating a smooth, planar reference path, given a family of discrete optimal paths. In conjunction with a path representation by a finite sequence of square cells, the generated path is supposed to stay inside a feasible channel, while minimizing certain performance criteria. Constrained optimization problems are formulated subject to geometric (linear) constraints, as well as boundary conditions in order to generate a library of B-spline path templates. As an application to the vehicle motion planning, the path templates are incorporated to represent local segments of the entire path as geometrically smooth curves, which are then joined with one another to generate a reference path to be followed by a closed-loop tracking controller. The on-line path generation algorithm incorporates the path templates such that continuity and smoothness are preserved when switching from one template to another along the path. Combined with the D∗-lite path planning algorithm, the proposed algorithm provides a complete solution to the obstacle-free path generation problem in a computationally efficient manner, suitable for real-time implementation.
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ItemModelling and Hardware-in-the-Loop Simulation for a Small Unmanned Aerial Vehicle(Georgia Institute of Technology, 2007-05) Jung, Dongwon ; Tsiotras, PanagiotisModeling and experimental identification results for a small unmanned aerial vehicle (UAV) are presented. The numerical values of the aerodynamic derivatives are computed via the Digital DATCOM software using the geometric parameters of the airplane. Flight test data are utilized to identify the stability and control derivatives of the UAV. The aerodynamic angles are estimated and used in conjunction with inertial measurements in a batch parameter identification algorithm. A hardware-in-the-loop (HIL) simulation environment is developed to support and validate the UAV autopilot hardware and software development. The HIL simulation incorporates a high-fidelity dynamic model that includes the sensor and actuator models, from the identified parameters from experiments. A user-friendly graphical interface that incorporates external stick commands and 3-D visualization of the vehicle’s motion completes the simulation environment. The hardware-in-the-loop setup is an indispensable tool for rapid certification of both the avionics hardware and the control software, while performing simulated flight tests with minimal cost and effort.
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ItemInertial Attitude and Position Reference System Development for a Small UAV(Georgia Institute of Technology, 2007-05) Jung, Dongwon ; Tsiotras, PanagiotisThis article presents an inexpensive inertial attitude and position reference system for a small unmanned aerial vehicle (UAV) that utilizes low cost inertial sensors in conjunction with a global positioning system (GPS) sensor. The attitude estimates are obtained from a complementary filter and a Kalman filter by combining the measurements from the inertial sensors with the supplementary attitude information from GPS. A method is proposed to deal with the GPS data latency and momentary outages. The inertial position is estimated from a separate Kalman filter that is cascaded after the attitude filters in order to reduce the computational overhead. Numerical simulation results and hardware validation show that this is a simple, yet effective method for attitude and position estimation, suitable for real-time implementation on a small UAV.
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ItemDesign and Development of a Low-Cost Test-Bed for Undergraduate Education in UAVs(Georgia Institute of Technology, 2005) Jung, Dongwon ; Jevy, E. J. ; Zhou, D. ; Fink, Richard W. ; Moshe, J. ; Earl, A. ; Tsiotras, PanagiotisThis article describes the efforts undertaken at the School of Aerospace Engineering at the Georgia Institute of Technology for the development of a low-cost Unmanned Aerial Vehicle (UAV) test-bed for educational purposes. The objective of this test-bed is to provide an avenue for the involvement of undergraduate students (primarily) and graduate students (secondarily) in UAV research. The complete design and development of all hardware interfaces of the UAV platform including the on-board autopilot is presented. Based on flight test data a linear model has been developed for the lateral and longitudinal dynamics.