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C. C. De Visser - One of the best experts on this subject based on the ideXlab platform.
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Probabilistic Flight Envelope Estimation with Application to Unstable Overactuated Aircraft
Journal of Guidance Control and Dynamics, 2019Co-Authors: Mingzhou Yin, Qiping Chu, Yong Zhang, Michael A. Niestroy, C. C. De VisserAbstract:This paper proposes a novel and practical framework for safe Flight Envelope estimation and protection, in order to prevent loss-of-control-related accidents. Conventional analytical Envelope estim...
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Database Building and Interpolation for an Online Safe Flight Envelope Prediction System
Journal of Guidance Control and Dynamics, 2019Co-Authors: Ye Zhang, C. C. De Visser, Qiping ChuAbstract:This paper reports the latest progress in the development of a database-driven safe Flight Envelope prediction system. By building up a database containing safe Flight Envelopes of different damage and fault scenarios, the challenges associated with online Flight Envelope prediction can be circumvented. The database is designed for different Flight conditions at which the Flight Envelopes are computed. Both longitudinal and lateral Envelopes are computed via the level set method, which shows obvious shrinkage between damaged and undamaged aircraft. It is found that by interpolating between two retrieved Envelopes in the database, more accurate results can be achieved.
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Safe Flight Envelope Uncertainty Quantification using Probabilistic Reachability Analysis
IFAC-PapersOnLine, 2018Co-Authors: R. Van Den Brandt, C. C. De VisserAbstract:Abstract Loss of Control is the primary contributor to aviation fatalities. To prevent this type of accident, Flight Envelope protection is considered to be a necessary development. The calculation of the Safe Flight Envelope provides a bound on the states that can safely be approached by the aircraft. Although theoretically accurate, some states may not be reachable under the influence of disturbances (e.g. turbulence). In this paper a stochastic extension to the reachability analysis is applied to a simplified aircraft model. The probabilistic reachability analysis yields the transition probability from a state to the target set. By comparing the deterministic and probabilistic Safe Flight Envelope, it becomes clear that the Safe Flight Envelope can shrink considerably under the influence of turbulence. It is shown that for a 3σ (99.7 %) confidence interval, the Envelope can shrink by as much as 50.8% compared to the deterministic Envelope. Furthermore, it is found that for high roll angles, some parts of the deterministic Envelope have a 0 % transition probability under the influence of turbulence, further emphasizing the importance of probabilistic Envelopes.
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Aircraft Damage Identification and Classification for Database-Driven Online Flight-Envelope Prediction
Journal of Guidance Control and Dynamics, 2018Co-Authors: Ye Zhang, C. C. De Visser, Q. P. ChuAbstract:Safe Flight-Envelope prediction is essential for preventing aircraft loss of control after the occurrence of sudden structural damage and aerodynamic failures. Considering the unpredictable nature of such failures, many challenges remain in the process of implementing such a prediction system. In this paper, an approach to online safe Flight-Envelope prediction is proposed that is based on the retrieval of information from offline-assembled databases. One of the key steps of this approach is determining the structural damage of the state of the aircraft by using the identification, detection, and classification methods presented in this paper. The estimated damage cases will lead to structural damage indices in the database corresponding to those safe Flight Envelopes that are “closest” to the actual safe Flight Envelope of the damaged aircraft. The feasibility of the proposed database-driven approach is proved by simulation results, where three damage cases are successfully detected and classified.
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Effects of Structural Failure on the Safe Flight Envelope of Aircraft
Journal of Guidance Control and Dynamics, 2018Co-Authors: Hafiz Noor Nabi, Qiping Chu, Yong Zhang, Thomas Lombaerts, E. Van Kampen, C. C. De VisserAbstract:The research presented in this paper focuses on the effects of structural failures on the safe Flight Envelope of an aircraft, which is the set of all the states in which safe maneuver of the aircr...
Thomas Lombaerts - One of the best experts on this subject based on the ideXlab platform.
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Proof of concept simulator demonstration of a physics based self-preserving Flight Envelope protection algorithm
Engineering Applications of Artificial Intelligence, 2018Co-Authors: Thomas Lombaerts, Gertjan Looye, Andreas Seefried, Miguel Neves, Tobias BellmannAbstract:This article discusses the development of an adaptive protection algorithm which is based on a physical approach, with the purpose to keep a closed loop aircraft with manual control laws within the actual safe Flight Envelope, even in the presence of failures or disturbances. Adaptive estimation of the Flight Envelope guarantees that not only flap changes, but also damage (e.g. icing) and external disturbances such as wind can be taken into account. This method is robust with respect to uncertainties in the estimates for the aerodynamic properties. This updated information makes the Flight control laws more self-preserving and prevents loss of control in Flight. This development can extend the functional Envelope of the nominal law and reduce the need to switch from nominal to alternate law in the presence of certain failures. This algorithm has been applied on a simulation model of a medium range passenger aircraft and the setup has been implemented and evaluated in the DLR Robotic Motion Simulator at the German Aerospace Center as a proof of concept demonstration. Adaptive Flight Envelope protections prevent loss of control for damaged aircraft in certain scenarios.Flight control laws become more self-preserving with improved autonomy thanks to these adaptive protections.The developed method is robust with respect to uncertainties in estimates of the aerodynamic properties.The functional Envelope of the nominal law is extended and the need to switch to alternate law for certain failures is reduced.A proof of concept demonstration has been given in the robotic motion simulator at DLR.
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Effects of Structural Failure on the Safe Flight Envelope of Aircraft
Journal of Guidance Control and Dynamics, 2018Co-Authors: Hafiz Noor Nabi, Qiping Chu, Yong Zhang, Thomas Lombaerts, E. Van Kampen, C. C. De VisserAbstract:The research presented in this paper focuses on the effects of structural failures on the safe Flight Envelope of an aircraft, which is the set of all the states in which safe maneuver of the aircr...
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Piloted Simulator Evaluation of Safe Flight Envelope Display Indicators for Loss of Control Avoidance
Journal of Guidance Control and Dynamics, 2017Co-Authors: Thomas Lombaerts, Stefan Schuet, Diana Acosta, John Kaneshige, Kimberlee H. Shish, Lynne MartinAbstract:In recent studies, it has been observed that loss of control in Flight is the most frequent primary cause of accidents. One of the technologies that will significantly reduce the risk of loss of control accidents is onboard safe Flight Envelope estimation. An efficient method for estimating the safe Flight Envelope for impaired aircraft has been implemented and evaluated in piloted simulations. This modular method is based on a physical approach. The aerodynamic system parameters are estimated from realistic noisy sensor measurements based on a probabilistic approach. These parameters are then used for efficient model-based computations of the trim Envelope as a set of equilibrium points that can be attained by means of admissible inputs. The safe maneuverability limitations are extended beyond the trim Envelope through a robust reachability analysis derived from an optimal control formulation. These trim and maneuvering Envelope limits can be used for multiple purposes. For example, they can be conveyed ...
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design and piloted simulator evaluation of adaptive safe Flight Envelope protection algorithm
Journal of Guidance Control and Dynamics, 2016Co-Authors: Thomas Lombaerts, Joost Ellerbroek, Gertjan Looye, Mitchell Rodriguez Y MartinAbstract:This paper discusses the design and evaluation of an efficient safe Flight Envelope protection method, for keeping a closed loop aircraft with manual control laws within the safe Envelope bounds. This Flight Envelope is estimated adaptively, so that configuration changes and possible impairment can be taken into account. The updated information of the safe Envelope is used in the Flight control laws to prevent loss of control in Flight. It has been found that a control architecture involving separate pilot command filtering is particularly well suited to incorporate these adaptive protections. Moreover, haptic feedback to the pilot controls can be included as well, based on the same adaptive bounds. This has the potential to further increase the Flight crew awareness about the risk of losing control in Flight. These algorithms have been evaluated in the Simona Research Simulator at Delft University of Technology, to investigate the impact on the awareness of the crew. Commercial airline crews flew multiple challenging approach and landing scenarios in a relevant environment. Results show that the algorithms support the Flight crew significantly. They contribute to ’care-free’ flying and to avoiding loss of control in Flight.
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design and evaluation of a Flight Envelope protection haptic feedback system
Analysis Design and Evaluation of Human-Machine Systems, 2016Co-Authors: Joost Ellerbroek, M Rodriguez J M Y Martin, Thomas Lombaerts, M M Van Paassen, Max MulderAbstract:Abstract: This paper describes the design and evaluation of a shared control, haptic feedback system to communicate Flight Envelope Protection System intent. The concept uses a combination of stiffness feedback and vibration to communicate proximity of the aircraft state to Flight Envelope boundaries. In addition, a stick center shift can be applied by the Envelope protection system to cooperatively perform corrective actions in case of severe excursions of the Envelope margins. Results from the evaluation experiment show improved performance with haptic feedback in both scenarios. Workload ratings were unaffected. Pilot opinion was unanimously positive, especially with regard to the combination of stiffness feedback and vibration cues.
Kostas J Kyriakopoulos - One of the best experts on this subject based on the ideXlab platform.
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a Flight Envelope determination and protection system for fixed wing uavs
International Conference on Robotics and Automation, 2020Co-Authors: Georgios Zogopoulospapaliakos, Kostas J KyriakopoulosAbstract:In this work we present a novel, approximate, efficient algorithm for determining the Trim Flight Envelope of a fixed-wing UAV, based on a generic, nonlinear numerical model. The resulting Flight Envelope is expressed as a convex intersection of half-spaces. Subsequently, a Model Predictive Controller (MPC) is designed which takes into account the Flight Envelope constraints, to avoid Loss-of-Control. The overall system is shown to operate in real-time in a simulation environment.
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ICRA - A Flight Envelope Determination and Protection System for Fixed-Wing UAVs
2020 IEEE International Conference on Robotics and Automation (ICRA), 2020Co-Authors: Georgios Zogopoulos-papaliakos, Kostas J KyriakopoulosAbstract:In this work we present a novel, approximate, efficient algorithm for determining the Trim Flight Envelope of a fixed-wing UAV, based on a generic, nonlinear numerical model. The resulting Flight Envelope is expressed as a convex intersection of half-spaces. Subsequently, a Model Predictive Controller (MPC) is designed which takes into account the Flight Envelope constraints, to avoid Loss-of-Control. The overall system is shown to operate in real-time in a simulation environment.
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A Fault-Tolerant Control Scheme for Fixed-Wing UAVs with Flight Envelope Integration
2020 International Conference on Unmanned Aircraft Systems (ICUAS), 2020Co-Authors: Georgios Zogopoulos-papaliakos, George C. Karras, Kostas J KyriakopoulosAbstract:Fault-tolerant control is currently the most important step towards increased autonomy for Unmanned Aerial Vehicles (UAVs). In this work, we consider actuator and airframe faults in fixed-wing UAVs and show that an online Flight Envelope (FE) calculation can interpret their effect on the achievable trim trajectories. Subsequently, we design a fully integrated control scheme with a RRT-based planner and 3 Nonlinear Model Predictive Control (MPC) layers. The FE is provided at each control layer with the beneficial result that non-trimmable, unstable trajectories are avoided. Results from high-fidelity simulations are provided.
Dennis S Bernstein - One of the best experts on this subject based on the ideXlab platform.
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exploration and mapping of an unknown Flight Envelope
Conference on Decision and Control, 2014Co-Authors: Ahmad Ansari, Dennis S BernsteinAbstract:The Flight Envelope of an aircraft consists of the constant trim states that the aircraft can attain, given in terms of airspeed, turn rate, and Flight path angle. Flight trajectories typically consist of a sequence of trim commands with intermediate transitions. While the Flight Envelope of an aircraft is determined beforehand, it may change under off-nominal conditions due to damage or actuator failure. The goal of this paper is to investigate the ability of an adaptive control law to reach new trim states in the case where the Flight Envelope is totally unknown. Within simulation, this approach provides an alternative technique for mapping the Flight Envelope. For an aircraft in Flight, this approach can be used to reach new trim states under Envelope uncertainty, as may occur during off-nominal Flight conditions.
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CDC - Exploration and mapping of an unknown Flight Envelope
53rd IEEE Conference on Decision and Control, 2014Co-Authors: Ahmad Ansari, Dennis S BernsteinAbstract:The Flight Envelope of an aircraft consists of the constant trim states that the aircraft can attain, given in terms of airspeed, turn rate, and Flight path angle. Flight trajectories typically consist of a sequence of trim commands with intermediate transitions. While the Flight Envelope of an aircraft is determined beforehand, it may change under off-nominal conditions due to damage or actuator failure. The goal of this paper is to investigate the ability of an adaptive control law to reach new trim states in the case where the Flight Envelope is totally unknown. Within simulation, this approach provides an alternative technique for mapping the Flight Envelope. For an aircraft in Flight, this approach can be used to reach new trim states under Envelope uncertainty, as may occur during off-nominal Flight conditions.
Naira Hovakimyan - One of the best experts on this subject based on the ideXlab platform.
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L1 Adaptive Control Within a Flight Envelope Protection System
Journal of Guidance Control and Dynamics, 2017Co-Authors: Hanmin Lee, Steven Snyder, Naira HovakimyanAbstract:An L1 adaptive control augmentation is presented for desired systems containing a feedforward term and is applied to a C⋆ controller within a Flight Envelope protection system for a transport-class...
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Automation situation awareness display for a Flight Envelope protection system
Journal of Guidance Control and Dynamics, 2017Co-Authors: Kasey A. Ackerman, Naira Hovakimyan, Donald A. Talleur, Ronald Carbonari, Enric Xargay, Benjamin D. Seefeldt, Alex Kirlik, Anna TrujilloAbstract:This paper presents an interface system display that is conceived to improve pilot situation awareness with respect to a Flight Envelope protection system, developed for a midsized transport aircra...
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design of a Flight Envelope protection system for nasa s transport class model
Journal of Guidance Control and Dynamics, 2017Co-Authors: Nikolas Tekles, Naira Hovakimyan, Donald A. Talleur, Enric Xargay, Ronald Choe, June Chongvisal, Christine M. BelcastroAbstract:This paper presents a Flight Envelope protection system for NASA’s Transport Class Model. The developed protection scheme is based on a command-limiting architecture that accounts for aircraft adverse aerodynamics, unusual attitude, and structural integrity and is designed to augment a standard gain-scheduled Flight control law. The scheme also includes an energy protection system, which relies on an automatic throttle control loop that implements a total energy control law. In the setup adopted, the limits of the protected Envelopes are actively adjusted to ensure, on the one hand, that the aircraft always stays in a safe Flight condition and, on the other hand, that the pilot has enough control authority to perform aggressive maneuvers, if needed. Batch simulations demonstrate the efficacy of the protection system in maintaining the aircraft within desired safe conditions.
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Flight Envelope Information-Augmented Display for Enhanced Pilot Situation Awareness
AIAA Infotech @ Aerospace, 2015Co-Authors: Kasey A. Ackerman, Naira Hovakimyan, Donald A. Talleur, Ronald Carbonari, Enric Xargay, Benjamin D. Seefeldt, Alex Kirlik, Anna Trujillo, Christine M. Belcastro, Irene M. GregoryAbstract:This paper presents an interface system display which is conceived to improve pilot situation awareness with respect to a Flight Envelope protection system developed for a mid-sized transport aircraft. The new display is designed to complement existing cockpit displays, and to augment them with information that relates to both aircraft state and the control automation itself. In particular, the proposed display provides cues about the state of automation directly in terms of pilot control actions, in addition to Flight parameters. The paper also describes a forthcoming evaluation test plan that is intended to validate the developed interface by assessing the relevance of the displayed information, as well as the adequacy of the display layout.
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Flight Envelope protection for NASA's transport class Model
AIAA Guidance Navigation and Control Conference, 2014Co-Authors: Nikolas Tekles, Naira Hovakimyan, Enric Xargay, Irene M. Gregory, Ronald Choe, Florian HolzapfelAbstract:Motivated by the problem of loss-of-control prevention, this paper presents a dynamic Flight Envelope protection system for NASA’s Transport Class Model. The developed protection scheme is based on a command-limiting approach that accounts for aircraft adverse aerodynamics, unusual attitude, and structural integrity, and is implemented around a standard gain-scheduled Flight control law. The scheme also includes an energy protection scheme, which relies on an automatic throttle control system that implements a total energy control law. Preliminary batch and pilot-in-the-loop simulations demonstrate the efficacy of the protection system in maintaining the aircraft within desired safe conditions, without limiting the ability of the pilot to perform aggressive, evasive maneuvers.