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Fault tolerant control and path planning for quasi-LPV systems : application to quadrotor

Abstract : Recently, autonomous systems are getting increasingly popular and are widely deployed in several applications in our daily life. That's why a great concern has been dedicated to the problem of autonomous systems fault-tolerant control (FTC). Evidently, the UAVs are among the systems that are in need of such FTC algorithms because any system malfunction can cause severe damage not just for the vehicle itself but for the surrounding environment as well. So this work is investigating the problem of designing an FTC algorithm for a quadrotor aiming to be a worthy contribution to the evolution of UAVs safety and reliability. Such a problem is tackled through some fundamental steps beginning with establishing a trustful model for the system representing the physical dynamics accurately. So Newton-Euler formulation is used for modeling the quadrotor resulting in a mathematical model that describes the relationship between the applied forces and the system states. After that the nonlinear model is linearized around the hovering point to simplify the control law design. A precise model could be constructed in an LPV framework where the nonlinear terms are considered as linearly time-varying within the given parameter limits. The deduced model is then used to build a controller that stabilizes the quadrotor and guarantees adequate trajectory tracking. So different types of control law are presented and analyzed some of them are linear controllers like PID provided with loop shaping technique. Other types of controllers presented are LQG to handle the system whose measurements are affected by Gaussian white noise and robust LPV control based on the H_inf technique to overcome unknown exogenous disturbances and measurement noise. In order to provide the quadrotor with an efficient FTC scheme, first, a fault detection and diagnosis (FDD) unit is proposed to identify the type, amount, and location of the existent fault. The FDD unit contains a model-based observer that generates some residual signals indicating the fault occurrence. According to the observer design, it may give just fault detection with a bank of observers for fault isolation or it can perform fault detection, estimation, and identification simultaneously. So an observer is designed based on H_/ H_inf technique aiming at maximizing the fault to residual sensitivity by using the H_ index properties, and minimizing the H_inf norm for worst-case exogenous signals attenuation. Afterward, a new approach is proposed for observer design based on an auxiliary output containing the system output and its successive time derivatives. This approach is used for both actuators and sensors fault diagnosis including fault detection, estimation, and isolation. It is illustrated that under some structural conditions, the faults can be estimated exactly while the perturbations are completely decoupled from the residual signals. However, if exact convergence is not ensured, some relaxed conditions are provided to maintain asymptotic fault estimation. Finally, the worst-case where the perturbations cannot be decoupled is presented and handled using H_/H_inf approach which is further enhanced utilizing the auxiliary output. Upon the obtained results from the actuator FDD unit, an active fault-tolerant control law is designed. After fault evaluation, the FDD gives a decision for the controller reconfiguration unit whether the actuator damage can be contained or not. For the first case, a control law is proposed aiming at fault compensation and precise trajectory tracking in the presence of system malfunction. For the latter case, a fail-safe mode is used to ensure that the quadrotor can land safely without crashing or causing harm to the surrounding environment.
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https://theses.hal.science/tel-03859631
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Submitted on : Friday, November 18, 2022 - 12:16:16 PM
Last modification on : Wednesday, November 23, 2022 - 9:59:00 PM

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2022UPAST085.pdf
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  • HAL Id : tel-03859631, version 1

Citation

Eslam Abouselima. Fault tolerant control and path planning for quasi-LPV systems : application to quadrotor. Automatic Control Engineering. Université Paris-Saclay, 2022. English. ⟨NNT : 2022UPAST085⟩. ⟨tel-03859631⟩

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