Examinando por Materia "TOLERANCIA A FALLOS"
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- Artículo de Publicación PeriódicaAnalysis and design of a tilted rotor hexacopter for fault tolerance(IEEE, 2016) Giribet, Juan I.; Sanchez-Peña, Ricardo; Ghersin, Alejandro S.A proof is presented of how a hexagon-shaped hexacopter can be designed to keep the ability to reject disturbance torques in all directions while counteracting the effect of a failure in any of its motors. The method proposed is simpler than previous solutions, because it does not require change of the motor rotation direction or in-flight mechanical reconfiguration of the vehicle. It consists of tilting the rotor a small fixed angle with respect to the vertical axis. Design guidelines are presented to calculate the tilt angle to achieve fault-tolerant attitude control without losing significant vertical thrust. It is also formally proved that the minimum number of unidirectional rotating motors needed to have fault tolerance is 6 and that this can be achieved by tilting their rotors. This proof is essentially a control allocation analysis that recovers in a simple way a result already known: the standard configuration (without tilting the motors) is not fault tolerant. A simulation example illustrates the theory.
- Artículo de Publicación PeriódicaData-driven fault diagnosis and robust control: application to PEM fuel cell systems(2018-08) Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo; Bianchi, Fernando D.; Ingimundarson, Ari"A data-driven methodology that includes the unfalsified control concept in the framework of fault diagnosis and isolation (FDI) and fault-tolerant control (FTC) is presented. The selection of the appropriate controller from a bank of controllers in a switching supervisory control setting is performed by using an adequate FDI outcome. By combining simultaneous online performance assessment of multiple controllers with the fault diagnosis decision from structured hypothesis tests, a diagnosis statement regarding what controller is most suitable to deal with the current (nominal or faulty) mode of the plant is obtained. Switching strategies that use the diagnosis statement are also proposed. This approach is applied to a nonlinear experimentally validated model of the breathing system of a polymer electrolyte membrane fuel cell. The results show the effectiveness of this FDI–fault-tolerant control data-driven methodology."
- Artículo de Publicación PeriódicaExperimental validation of a fault-tolerant hexacopter with tilted rotors(2018) Giribet, Juan I.; Pose, Claudio D.; Ghersin, Alejandro S.; Mas, Ignacio"Recently, research reporting the advantages of flying with tilted-motor multicopters has surfaced. Particularly, it has been theoretically proven that in the case of a complete failure of one of the motors in a hexagon-shaped hexacopter, complete altitude and attitude control can be maintained. In this work, these theoretical results were experimentally validated."
- Ponencia en CongresoFault tolerance analysis of a hexarotor with reconfigurable tilted rotors(2020) Pose, Claudio D.; Giribet, Juan I.; Mas, Ignacio"Tilted rotors in multirotor vehicles have shown to be useful for different practical reasons. For instance, increasing yaw maneuverability or enabling full position and attitude control of hexarotor vehicles. It has also been proven that a hexagon-shaped multirotor is capable of complete attitude and altitude control under failures of one of its rotors. However, when a rotor fails, the torque that can be reached in the worstcase direction decreases considerably. This work proposes to actively change the tilt angle of the rotors when a failure occurs. This rotor reconfiguration increases the maximum torque that can be achieved in the most stressful direction, reducing maneuverability limitations. Experimental validations are shown, where the proposed reconfigurable tilted rotor is used in order to control a hexarotor vehicle when a failure appears mid-flight. The impact of the delay in the reconfiguration when a failure occurs is also addressed."
- Ponencia en CongresoFault tolerance analysis of a multirotor with 6DOF(2019-09) Giribet, Juan I.; Pose, Claudio D.; Mas, Ignacio"Several works have addressed the issue of obtaining a six degree of freedom (6DOF) capable multirotor. However, the capability of keeping full control in the case of a total failure in one of the rotors has not yet been analyzed. In this work, it is proven that eight is the minimum number of rotors necessary to achive 6DOF control of a multirotor, in the case of a total failure in one of them. Also, an octorotor configuration with 6DOF control capabilities in a failure situation is proposed and analyzed through numerical simulations, comparing its flight performance in a nominal and a failure case. "
- Ponencia en CongresoFault tolerant control of an hexacopter with a tilted-rotor configuration(2017) Giribet, Juan I.; Pose, Claudio D.; Mas, Ignacio"Recently, it was shown that an hexagon-shaped hexa-rotor micro aerial vehicle with unidirectionally spinning tilted rotors is capable of fault tolerant attitude and altitude control. This result has been theoretically proven and validated by simulations. However, experimental results have never been reported yet. In this work experimental results are presented, and a comparison between a tilted-rotor hexacopter with one in a standard rotor configuration is carried out."
- Ponencia en CongresoFault tolerant control of an hexacopter with a tilted-rotor configuration(2020) Giribet, Juan I.; Pose, Claudio D.; Mas, Ignacio"Recientemente, han surgido algunos trabajos reportando las ventajas de volar con multicópteros con rotores inclinados, es decir, rotores que no apunten en la dirección de la vertical del vehículo. En particular, se demostró que para lograr un vehículo hexa-rotor capaz de tolerar fallas en uno de sus rotores es necesario que éstos estén inclinados. Hasta el momento, las validaciones experimentales de estos resultados han considerado fallas parciales en los rotores. Más precisamente, se han analizado casos en los cuales uno de los rotores pierde capacidad de empuje. Sin embargo, los resultados teóricos admiten una falla total de los rotores, es decir, que uno de los rotores se detenga completamente. En este trabajo validamos experimentalmente la falla total de un rotor y mostramos cómo un vehículo hexa-rotor es capaz de mantener su capacidad de maniobra ante la pérdida total de uno de sus rotores."
- Capítulo de libroFault-tolerant systems for unmanned multirotor aerial vehicles(2020) Giribet, Juan I.; Pose, Claudio D.; Mas, Ignacio"This chapter presents some recent results on fault-tolerant control systems for unmanned aerial systems, in particular for multirotor-type vehicles, commonly known as drones. Over the last years, these vehicles have become widely popular. Simplicity and cost-effectiveness have turned out to be very appealing and, as a consequence, an increasing number of applications have risen in many fields such as agriculture, surveillance, and photography, among others. As mission requirements become more demanding, the matter of fault tolerance emerges as a key challenge, especially if system certification is sought. Here, the focus is placed particularly on rotor failures in multirotor vehicles, and a specific definition for fault tolerance is considered based on the maneuverability capabilities in case of a failure. A geometric analysis is presented to evaluate the fault tolerant capabilities of a given vehicle, together with an experimental validation. Then, the limitations of this concept are analyzed. Finally, a novel reconfigurable structure is proposed for a fault-tolerant hexarotor, that presents good flight performance in failure cases, together with experimental results."
- Ponencia en CongresoHexacopter fault tolerant actuator allocation analysis for optimal thrust(2017) Pose, Claudio D.; Giribet, Juan I.; Ghersin, Alejandro S."Recently, it was shown that an hexagon shaped hexarotor vehicle with tilted rotors, is capable of fault tolerant attitude and altitude control. In this work, we propose a strategy to select the signals commanded to each rotor in order to achieve a desired torque and vertical force. The proposed strategy is optimal in the sense that minimizes the maximum force exerted by the rotors. A comparison with the commonly used strategy based upon the Moore-Penrose pseudoinverse is carried out. It is shown that, with the optimal strategy proposed here, maneuverability is improved, because the new method takes into account the actuators constraints. Although the optimal strategy is computationally more demanding than the classical method, the additional computational burden is not significant when both strategies are compared in a real application. To show this, both algorithms were programmed in an autopilot based on an ARM Cortex M3 microcontroller, and the experimental results are presented."