The Experts below are selected from a list of 53970 Experts worldwide ranked by ideXlab platform
Changdon Kee - One of the best experts on this subject based on the ideXlab platform.
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Design and Flight Test of Flight Control System for a Small Endurance UAV Only Using 4 Hz Single-Antenna GPS Receiver
2010Co-Authors: Am Cho, Changdon Kee, Jihoon Kim, Samok GooAbstract:In other works, it was shown that automatic control of UAV is possible using a Single-Antenna GPS receiver only. Single-Antenna GPS receiver is used widely as a navigation sensor for numerous applications including unmanned aerial vehicles (UAVs). It provides position and velocity measurements, from which pseudo-attitudes can also be synthesized for a fixed wing aircraft. This suggests the potential of Single-Antenna GPS receiver as the sole sensor of the aircraft. Based on the experience of previous work, this paper develops the flight control system for a small endurance UAV only using a low-cost Single-Antenna GPS receiver that provides navigation solution at 4 Hz. The small endurance UAV developed by Korea Aerospace Research Institute is a tailless flyingwing UAV with elevon and two wingtip rudders as control surfaces. Linearized system models, which are different from traditional fixed-wing aircraft, are obtained by system identification process. Based on the identified model, linear quadratic regulator controllers are designed. Various simulations and flight tests are conducted to verify the developed system. During flight tests, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single-Antenna GPS receiver based attitude determination system. Flight test results verified again the value of proposed flight control system and showed that it could be applied to tailless flying-wing UAV successfully.
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Fully Automatic Taxiing, Takeoff and Landing of a UAV only with a Single-Antenna GPS Receiver
2008Co-Authors: Am Cho, Sanghyo Lee, Dongkeon Kim, Jihoon Kim, Changdon KeeAbstract:[Abstract] This paper deals with automatic takeoff and landing of a UAV using a Single Antenna GPS receiver only. In this paper, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single -Antenna GPS receiver based attitude determination system. DGPS is implemented to give high accuracy position information for automatic landing and takeoff on the runway. In addition to GPS receiver , only an airspeed sen sor is added because the velocity relative to the air is very important during landing and takeoff. For a fixed wing aircraft, the attitude information called as pseudo -attitudes can be estimated from the measurements of a Single -Antenna GPS receiver under the assumption of coordinated flight . From linearized equations of motions around the steady state, LQR controllers f or takeoff and landing are buil t. In particular, for the flare control, the controller that controls the pitch, altitude and airspeed of a UAV is designe d. During flight tests, the aircraft taxies and takes off the runway, follows the predefined waypoint path, and then lands on the runway along the curved approach path, all fully automatically. The flight test results show that a Single -ante nna GPS receiver can be used as a main sensor for a backup or a low -cost control system of UAVs.
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Vision-based real-time target localization for Single-Antenna GPS-guided UAV
IEEE Transactions on Aerospace and Electronic Systems, 2008Co-Authors: Subong Sohn, Bhoram Lee, Jihoon Kim, Changdon KeeAbstract:This paper discusses a real-time method to calculate the three-dimensional location of a fixed target detected by a gimbaled camera in a fixed-wing experimental unmanned aerial vehicle (UAV) equipped with a Single-Antenna GPS receiver on board. The camera was operated by an algorithm that automatically tracked the detected target, and the location was obtained using triangulation. The algorithm, however, suffers from a bias in target localization, because the aircraft Euler angles are not measured directly, but rather inferred from GPS velocity. To enhance the algorithm, the influence of the wind was taken into consideration to improve the localization accuracy, which cannot be deduced using a Single-Antenna GPS. Using a special maneuver, the circular level flight, wind velocity was estimated by the periodic variation of the aircraft's velocity and angle of attack (AOA) using the camera angles. Then, the pseudopitch angle was compensated for using the estimated results. The experimental data show that applying the pitch angle calibration successfully eliminated almost 90% of the horizontal localization error and the final 3D accuracy was less than 10 m.
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Fully automatic taxiing, takeoff and landing of a UAV based on a Single-Antenna GNSS receiver
IFAC Proceedings Volumes, 2008Co-Authors: Am Cho, Sanghyo Lee, Bosung Kim, Noha Park, Dongkeon Kim, Jihoon Kim, Changdon KeeAbstract:This paper presents fully automatic control of an unmanned aerial vehicle (UAV) from taxiing and takeoff to landing based on a Single-Antenna GPS receiver. In this paper, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single-Antenna GPS receiver based attitude determination system. DGPS is implemented to give high accuracy position information for automatic taxiing, landing and takeoff on the runway. For a fixed wing aircraft, under the assumption of coordinated flight, the attitude information called as pseudo-attitudes can be estimated from the measurements of a Single-Antenna GPS receiver. Therefore full state variables for the automatic control can be obtained from Single-Antenna GPS receiver. In addition to GPS receiver, only an airspeed sensor is added because the velocity relative to the air is very important during landing and takeoff. The forward velocity is replaced with the airspeed obtained from Pitot tube. From linearized equations of motions around the steady state, LQR controllers for takeoff and landing are built. In particular, the flare controller that controls the pitch, altitude and airspeed of a UAV is designed. During flight tests, the aircraft taxies and takes off the runway, follows the predefined waypoint path, and then lands on the runway along the curved approach path, all fully automatically. Based on flight test results, a Single-Antenna GPS receiver can be used as a main sensor for a backup or a low-cost control system of UAVs
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Fully automatic taxiing, takeoff and landing of a UAV using a Single-Antenna GPS receiver only
ICCAS 2007 - International Conference on Control Automation and Systems, 2007Co-Authors: Am Cho, Sanghyo Lee, Bosung Kim, Noha Park, Dongkeon Kim, Sujin Choi, Jihoon Kim, Boram Lee, Changdon KeeAbstract:This paper presents automatic taxiing, takeoff and landing of a UAV based on a Single-Antenna GPS receiver. In this paper, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single-Antenna GPS receiver based attitude determination system. DGPS is implemented to give high accuracy position information for automatic taxiing, landing and takeoff on the runway. For a fixed wing aircraft, under the assumption of coordinated flight, the attitude information called as pseudo-attitudes can be estimated from the measurements of a Single-Antenna GPS receiver. So full state variables for the automatic control can be obtained from Single-Antenna GPS receiver. In addition to GPS receiver, only an airspeed sensor is added because the velocity relative to the air is very important during landing and takeoff. The forward velocity is replaced with the airspeed obtained from Pitot tube. From linearized equations of motions around the steady state, LQR controllers for takeoff and landing are built, m particular, the flare controller that controls the pitch, altitude and airspeed of a UAV is designed. During flight tests, the aircraft taxies and takes off the runway, follows the predefined waypoint path, and then lands on the runway along the curved approach path, all fully automatically. Based on flight test results, a Single-Antenna GPS receiver can be used as a main sensor for a backup or a low-cost control system of UAVs.
Amir K. Khandani - One of the best experts on this subject based on the ideXlab platform.
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On the secure DoF of the Single-Antenna MAC
2010 IEEE International Symposium on Information Theory, 2010Co-Authors: Ghadamali Bagherikaram, Abolfazl S. Motahari, Amir K. KhandaniAbstract:A new achievability rate region for the secure discrete memoryless Multiple-Access-Channel (MAC) is presented. Thereafter, a novel secure coding scheme is proposed to achieve a positive Secure Degrees-of-Freedom (S-DoF) in the Single-Antenna MAC. This scheme converts the Single-Antenna system into a multiple-dimension system with fractional dimensions. The achievability scheme is based on the alignment of signals into a small sub-space at the eavesdropper, and the simultaneous separation of the signals at the intended receiver. Tools from the field of Diophantine Approximation in number theory are used to analyze the probability of error in the coding scheme.
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ISIT - On the secure DoF of the Single-Antenna MAC
2010 IEEE International Symposium on Information Theory, 2010Co-Authors: Ghadamali Bagherikaram, Abolfazl S. Motahari, Amir K. KhandaniAbstract:A new achievability rate region for the secure discrete memoryless Multiple-Access-Channel (MAC) is presented. Thereafter, a novel secure coding scheme is proposed to achieve a positive Secure Degrees-of-Freedom (S-DoF) in the Single-Antenna MAC. This scheme converts the Single-Antenna system into a multiple-dimension system with fractional dimensions. The achievability scheme is based on the alignment of signals into a small sub-space at the eavesdropper, and the simultaneous separation of the signals at the intended receiver. Tools from the field of Diophantine Approximation in number theory are used to analyze the probability of error in the coding scheme.
Giuseppe Durisi - One of the best experts on this subject based on the ideXlab platform.
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On Single-Antenna Rayleigh Block-Fading Channels at Finite Blocklength
IEEE Transactions on Information Theory, 2020Co-Authors: Alejandro Lancho, Tobias Koch, Giuseppe DurisiAbstract:This article concerns the maximum coding rate at which data can be transmitted over a noncoherent, Single-Antenna, Rayleigh block-fading channel using an error-correcting code of a given blocklength with a block-error probability not exceeding a given value. A high-SNR normal approximation of the maximum coding rate is presented that becomes accurate as the signal-to-noise ratio (SNR) and the number of coherence intervals $L$ over which we code tend to infinity. Numerical analyses suggest that the approximation is accurate at SNR values above 15dB and when the number of coherence intervals is 10 or more.
Besma Smida - One of the best experts on this subject based on the ideXlab platform.
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A Comprehensive Self-interference Model for Single-Antenna Full-duplex Communication Systems
arXiv: Signal Processing, 2019Co-Authors: Atiqul Islam, Besma SmidaAbstract:Single-Antenna full-duplex communication technology has the potential to substantially increase spectral efficiency. However, limited propagation domain cancellation of Single-Antenna system results in a higher impact of receiver chain nonlinearities on the residual self-interference (SI) signal. In this paper, we offer a comprehensive SI model for Single-Antenna full-duplex systems based on direct-conversion transceiver structure considering nonlinearities of all the transceiver radio frequency (RF) components, in-phase/quadrature (IQ) imbalances, phase noise effect, and receiver noise figure. To validate our model, we also propose a more appropriate digital SI cancellation approach considering receiver chain RF and baseband nonlinearities. The proposed technique employs orthogonalization of the design matrix using QR decomposition to alleviate the estimation and cancellation error. Finally, through circuit-level waveform simulation, the performance of the digital cancellation strategy is investigated, which achieves 20 dB more cancellation compared to existing methods.
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ICC - A Comprehensive Self-Interference Model for Single-Antenna Full-Duplex Communication Systems
ICC 2019 - 2019 IEEE International Conference on Communications (ICC), 2019Co-Authors: Atiqul Islam, Besma SmidaAbstract:Single-Antenna full-duplex communication technology has the potential to substantially increase spectral efficiency. However, limited propagation domain cancellation of Single-Antenna system results in a higher impact of receiver chain nonlinearities on the residual self-interference (SI) signal. In this paper, we offer a comprehensive SI model for Single-Antenna full-duplex systems based on direct-conversion transceiver structure considering nonlinearities of all the transceiver radio frequency (RF) components, in-phase/quadrature (IQ) imbalances, phase noise effect, and receiver noise figure. To validate our model, we also propose a more appropriate digital SI cancellation approach considering receiver chain RF and baseband nonlinearities. The proposed technique employs orthogonalization of the design matrix using QR decomposition to alleviate the estimation and cancellation error. Finally, through circuit-level waveform simulation, the performance of the digital cancellation strategy is investigated, which achieves 20 dB more cancellation compared to existing methods.
Am Cho - One of the best experts on this subject based on the ideXlab platform.
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Design and Flight Test of Flight Control System for a Small Endurance UAV Only Using 4 Hz Single-Antenna GPS Receiver
2010Co-Authors: Am Cho, Changdon Kee, Jihoon Kim, Samok GooAbstract:In other works, it was shown that automatic control of UAV is possible using a Single-Antenna GPS receiver only. Single-Antenna GPS receiver is used widely as a navigation sensor for numerous applications including unmanned aerial vehicles (UAVs). It provides position and velocity measurements, from which pseudo-attitudes can also be synthesized for a fixed wing aircraft. This suggests the potential of Single-Antenna GPS receiver as the sole sensor of the aircraft. Based on the experience of previous work, this paper develops the flight control system for a small endurance UAV only using a low-cost Single-Antenna GPS receiver that provides navigation solution at 4 Hz. The small endurance UAV developed by Korea Aerospace Research Institute is a tailless flyingwing UAV with elevon and two wingtip rudders as control surfaces. Linearized system models, which are different from traditional fixed-wing aircraft, are obtained by system identification process. Based on the identified model, linear quadratic regulator controllers are designed. Various simulations and flight tests are conducted to verify the developed system. During flight tests, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single-Antenna GPS receiver based attitude determination system. Flight test results verified again the value of proposed flight control system and showed that it could be applied to tailless flying-wing UAV successfully.
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Fully Automatic Taxiing, Takeoff and Landing of a UAV only with a Single-Antenna GPS Receiver
2008Co-Authors: Am Cho, Sanghyo Lee, Dongkeon Kim, Jihoon Kim, Changdon KeeAbstract:[Abstract] This paper deals with automatic takeoff and landing of a UAV using a Single Antenna GPS receiver only. In this paper, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single -Antenna GPS receiver based attitude determination system. DGPS is implemented to give high accuracy position information for automatic landing and takeoff on the runway. In addition to GPS receiver , only an airspeed sen sor is added because the velocity relative to the air is very important during landing and takeoff. For a fixed wing aircraft, the attitude information called as pseudo -attitudes can be estimated from the measurements of a Single -Antenna GPS receiver under the assumption of coordinated flight . From linearized equations of motions around the steady state, LQR controllers f or takeoff and landing are buil t. In particular, for the flare control, the controller that controls the pitch, altitude and airspeed of a UAV is designe d. During flight tests, the aircraft taxies and takes off the runway, follows the predefined waypoint path, and then lands on the runway along the curved approach path, all fully automatically. The flight test results show that a Single -ante nna GPS receiver can be used as a main sensor for a backup or a low -cost control system of UAVs.
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Fully automatic taxiing, takeoff and landing of a UAV based on a Single-Antenna GNSS receiver
IFAC Proceedings Volumes, 2008Co-Authors: Am Cho, Sanghyo Lee, Bosung Kim, Noha Park, Dongkeon Kim, Jihoon Kim, Changdon KeeAbstract:This paper presents fully automatic control of an unmanned aerial vehicle (UAV) from taxiing and takeoff to landing based on a Single-Antenna GPS receiver. In this paper, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single-Antenna GPS receiver based attitude determination system. DGPS is implemented to give high accuracy position information for automatic taxiing, landing and takeoff on the runway. For a fixed wing aircraft, under the assumption of coordinated flight, the attitude information called as pseudo-attitudes can be estimated from the measurements of a Single-Antenna GPS receiver. Therefore full state variables for the automatic control can be obtained from Single-Antenna GPS receiver. In addition to GPS receiver, only an airspeed sensor is added because the velocity relative to the air is very important during landing and takeoff. The forward velocity is replaced with the airspeed obtained from Pitot tube. From linearized equations of motions around the steady state, LQR controllers for takeoff and landing are built. In particular, the flare controller that controls the pitch, altitude and airspeed of a UAV is designed. During flight tests, the aircraft taxies and takes off the runway, follows the predefined waypoint path, and then lands on the runway along the curved approach path, all fully automatically. Based on flight test results, a Single-Antenna GPS receiver can be used as a main sensor for a backup or a low-cost control system of UAVs
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Fully automatic taxiing, takeoff and landing of a UAV using a Single-Antenna GPS receiver only
ICCAS 2007 - International Conference on Control Automation and Systems, 2007Co-Authors: Am Cho, Sanghyo Lee, Bosung Kim, Noha Park, Dongkeon Kim, Sujin Choi, Jihoon Kim, Boram Lee, Changdon KeeAbstract:This paper presents automatic taxiing, takeoff and landing of a UAV based on a Single-Antenna GPS receiver. In this paper, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single-Antenna GPS receiver based attitude determination system. DGPS is implemented to give high accuracy position information for automatic taxiing, landing and takeoff on the runway. For a fixed wing aircraft, under the assumption of coordinated flight, the attitude information called as pseudo-attitudes can be estimated from the measurements of a Single-Antenna GPS receiver. So full state variables for the automatic control can be obtained from Single-Antenna GPS receiver. In addition to GPS receiver, only an airspeed sensor is added because the velocity relative to the air is very important during landing and takeoff. The forward velocity is replaced with the airspeed obtained from Pitot tube. From linearized equations of motions around the steady state, LQR controllers for takeoff and landing are built, m particular, the flare controller that controls the pitch, altitude and airspeed of a UAV is designed. During flight tests, the aircraft taxies and takes off the runway, follows the predefined waypoint path, and then lands on the runway along the curved approach path, all fully automatically. Based on flight test results, a Single-Antenna GPS receiver can be used as a main sensor for a backup or a low-cost control system of UAVs.
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Fully Automatic Taxiing, Takeoff and Landing of a VAV using a Single-Antenna GPS Receiver only
2007Co-Authors: Am Cho, Sanghyo Lee, Bosung Kim, Noha Park, Dongkeon Kim, Changdon Kee, Sujin Choi, Jihoon Kim, Boram Lee, Gnss LabAbstract:This paper presents automatic taxiing, takeoff and landing of a UAV based on a Single-Antenna GPS receiver. In this paper, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a Single-Antenna GPS receiver based attitude determination system. DGPS is implemented to give high accuracy position information for automatic taxiing, landing and takeoff on the runway. For a fixed wing aircraft, under the assumption of coordinated flight, the attitude information called as pseudo-attitudes can be estimated from the measurements of a Single-Antenna GPS receiver. So full state variables for the automatic control can be obtained from Single-Antenna GPS receiver. In addition to GPS receiver, only an airspeed sensor is added because the velocity relative to the air is very important during landing and takeoff The forward velocity is replaced with the airspeed obtained from Pitot tube. From linearized equations of motions around the steady state, LQR controllers for takeoff and landing are built. In particular, the flare controller that controls the pitch, altitude and airspeed of a UAV is designed. During flight tests, the aircraft taxies and takes off the runway, follows the predefined waypoint path, and then lands on the runway along the curved approach path, all fully automatically. Based on flight test results, a Single-Antenna GPS receiver can be used as a main sensor for a backup or a low-cost control system ofUAVs
