Browsing by Author "Souanef, Toufik"
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Item Open Access Design and implementation of an L1 adaptive proportional output feedback controller(MDPI, 2024-05-02) Bagati, Deepanshu; Souanef, Toufik; Whidborne, James F.A new approach for output feedback ℒ1 adaptive control based on a proportional adaptation law is presented. The effectiveness of this design is assessed in simulation and validated through real-time testing on an airfoil pitch control wind tunnel experimental rig. Experimental evaluation of the robustness of the controllers, assessed by introducing various disturbances into the control signals, shows that the adaptive control has a better performance compared to PID control, particularly in scenarios with reduced control effectiveness and time-varying disturbances. The experimental results demonstrate the efficacy of the proposed method in practical applications.Item Open Access Digital twin development for the airspace of the future(MDPI, 2023-07-23) Souanef, Toufik; Al-Rubaye, Saba; Tsourdos, Antonios; Ayo, Samuel; Panagiotakopoulos, DimitriosThe UK aviation industry is committed to achieving net zero emissions by 2050 through sustainable measures and one of the key aspects of this effort is the implementation of Unmanned Traffic Management (UTM) systems. These UTM systems play a crucial role in enabling the safe and efficient integration of unmanned aerial vehicles (UAVs) into the airspace. As part of the Airspace of the Future (AoF) project, the development and implementation of UTM services have been prioritised. This paper aims to create an environment where routine drone services can operate safely and effectively. To facilitate this, a digital twin of the National Beyond Visual Line of Sight Experimentation Corridor has been created. This digital twin serves as a virtual replica of the corridor and allows for the synthetic testing of unmanned traffic management concepts. The implementation of the digital twin involves both simulated and hybrid flights with real drones. Simulated flights allow for the testing and refinement of UTM services in a controlled environment. Hybrid flights, on the other hand, involve the integration of real drones into the airspace to assess their performance and compatibility with the UTM systems. By leveraging the capabilities of UTM systems and utilising the digital twin for testing, the AoF project aims to advance the development of safer and more efficient drone operations. The Experimentation Corridor has been developed to simulate and test concepts related to managing unmanned traffic. The paper provides a detailed account of the implementation of the digital twin for the AoF project, including simulated and hybrid flights involving real drones.Item Open Access L1 adaptive fault‑tolerant control of stratospheric airships(Springer, 2024-03-26) Souanef, Toufik; Whidborne, James F.; Liu, Shi QianAs the utilization of stratospheric airships becomes more prevalent, ensuring their safe operation becomes crucial. This paper explores the ability of an L1 adaptive controller to maintain fault tolerance in the actuators of a stratospheric airship. L1 adaptive control offers fast adaptation while separating adaptation and robustness. This makes the approach a suitable candidate for fault-tolerant control. The performance of the proposed design is compared to the Linear Quadratic Integral and Adaptive Sliding Mode Backstepping controllers. Simulation results show that the robustness of the airship model against faults is improved with the use of the L1 adaptive controller.Item Open Access Multiple model L1 adaptive fault-tolerant control of small unmanned aerial vehicles(American Society of Civil Engineers, 2023-11-09) Souanef, ToufikThis paper presents a method for fault-tolerant control of small fixed-wing Unmanned Aerial Vehicles (UAVs). The proposed design is based on multiple-model L1 adaptive control. The controller is composed of a nominal reference model and a set of suboptimal reference models. The nominal model is the one with desired dynamics that are optimal regarding some specific criteria. In a suboptimal model the performance criteria are reduced, it is designed to ensure system robustness in the presence of critical failures. The controller was tested in simulations and it was shown that the multiple model L1 adaptive controller stabilizes the system in case of inversion of the control input, while the L1 adaptive controller with a single nominal model fails.Item Open Access ℒ1 adaptive control of quadrotor UAVs in case of inversion of the torque direction(SCIE Publish, 2023-10-10) Souanef, Toufik; Whidborne, James F.; Boubakir, AhseneThis paper presents a method for fault tolerant control of quadrotor UAVs in case of inversion of the torque direction, a situation that might occur due to structural, hardware or software issues. The proposed design is based on multiple-model ℒ1 adaptive control. The controller is composed of a nominal reference model and a set of degraded reference models. The nominal model is that with desired dynamics that are optimal regarding some specific criteria. In a degraded model, the performance criteria are reduced. It is designed to ensure system robustness in the presence of critical failures. The controller is tested in simulations and it is shown that the multiple model ℒ1 adaptive controller stabilizes the system in case of inversion of the control input, while the ℒ1 adaptive controller with a single nominal model fails.Item Open Access ℒ1 adaptive output feedback control of small unmanned aerial vehicles(World Scientific Publishing, 2022-07-22) Souanef, ToufikAn approach for output feedback ℒ1 adaptive control of small Unmanned Aerial Vehicles (UAVs) is presented in this paper. The design is based on a state observer instead of the state predictor. The main advantage is that a full state measurement can be avoided, and the design and implementation of the controller are simplified. Furthermore, since the state space description is maintained, the system dynamics including uncertainties can be specified with physical insight, which simplifies practical applications. The adaptation law borrows insights from the sliding mode control to estimate the unknown bounds of external disturbances. Flight test results for the control of a small UAV show the robustness of the ℒ1 adaptive controller to large uncertainties and disturbances.Item Open Access ℒ1 adaptive path-following of airships in wind(World Scientific, 2023-05-06) Souanef, Toufik; Whidborne, James F.; Liu, Shi QianThis paper proposes an adaptive, three dimensional (3D) path-following controller for airships in the presence of wind disturbances, which explicitly considers that wind speed is time-varying. The main idea is to formulate airship path-following as control design for systems in the presence of parametric uncertainties and external disturbances. Assuming that there is no prior information on wind, the proposed solution is based on the ℒ1 adaptive controller. This approach makes clear statements for performance specifications of the controller and relaxes the common assumption that wind speed is constant. This makes the design more realistic and the analysis more rigorous, because in practice, the wind speed may be time varying. The results of the simulation indicate that the path following system has a good performance and is robust against wind disturbances.Item Open Access ℒ1 adaptive path-following of small fixed-wing unmanned aerial vehicles in wind(IEEE, 2022-02-25) Souanef, ToufikThis paper proposes an adaptive path-following controller of small fixed-wing Unmanned Aerial Vehicles (UAVs) in the presence of wind disturbances, which explicitly considers that wind speed is time-varying. The main idea was to formulate UAVs path-following as control design for systems with parametric uncertainties and external disturbances. Assuming that there is no prior information on wind, the proposed solution is based on the ℒ1 adaptive control, using linearized model dynamics. This approach makes clear statements for performance specifications of the controller and relaxes the common constant wind velocity assumption. This makes the design more realistic and the analysis more rigorous, because in practice wind is usually time varying (windshear, turbulence and gusting). The path-following controller was demonstrated in flight under wind speed up to 10m/s, representing 50% of the nominal UAV airspeed.