Two-layer adaptive augmentation for incremental backstepping flight control of transport aircraft in uncertain conditions

Presence of uncertainties caused by unforeseen malfunctions in actuation system or changes in aircraft behaviour could lead to aircraft loss-of-control during flight. The paper presents Two-Layer Adaptive augmentation for Incremental Backstepping (TLA-IBKS) control algorithm designed for a large transport aircraft. IBKS uses angular accelerations and current control deflections to reduce the dependency on the aircraft model. However, it requires knowledge of control effectiveness. The proposed technique is capable to detect possible failures for an overactuated system. At the first layer, the system performs monitoring of a combined effectiveness and detects possible failures via an innovation process. If a problem is detected the algorithm initiates the second-layer algorithm for adaptation of effectiveness of individual control effectors. Filippov generalization for nonlinear differential equations with discontinuous right-hand sides is utilized to develop Lyapunov based tuning function adaptive law for the second layer adaptation and to prove uniform asymptotic stability of the resultant closed-loop system. Conducted simulation manifests that if the input-affine property of the IBKS is violated, e.g., in severe conditions with a combination of multiple failures, the IBKS can lose stability. Meanwhile, the proposed TLA-IBKS algorithm demonstrates improved stability and tracking performance

A fault tolerant direct control allocation scheme with integral sliding modes

PublishedJournal Article© by Mirza Tariq Hamayun 2015. In this paper, integral sliding mode control ideas are combined with direct control allocation in order to create a fault tolerant control scheme. Traditional integral sliding mode control can directly handle actuator faults; however, it cannot do so with actuator failures. Therefore, a mechanism needs to be adopted to distribute the control effort amongst the remaining functioning actuators in cases of faults or failures, so that an acceptable level of closed-loop performance can be retained. This paper considers the possibility of introducing fault tolerance even if fault or failure information is not provided to the control strategy. To demonstrate the efficacy of the proposed scheme, a high fidelity nonlinear model of a large civil aircraft is considered in the simulations in the presence of wind, gusts and sensor noise.This paper was partially funded by the Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah, under the grant no. Gr/33/5. The first and the last author, therefore, acknowledge with thanks the DSR financial support

Novel frameworks for the design of fault-tolerant control using optimal sliding-mode control

Copyright © 2018 John Wiley & Sons, Ltd. This paper describes 2 schemes for a fault-tolerant control using a novel optimal sliding-mode control, which can also be employed as actuator redundancy management for overactuated uncertain linear systems. By using the effectiveness level of the actuators in the performance indexes, 2 schemes for redistributing the control effort among the remaining (redundant or nonfaulty) set of actuators are constructed based on an H2-based optimal sliding-mode control. In contrast to the current sliding-mode fault-tolerant control design methods, in these new schemes, the level of control effort required to maintain sliding is penalised. The proposed optimal sliding-mode fault-tolerant control design schemes are implemented in 2 stages. In the first stage, a state feedback gain is derived using an LMI-based scheme that can assign a number of the closed-loop eigenvalues to a known value whilst satisfying performance specifications. The sliding function matrix related to the particular state feedback derived in the first stage is obtained in the second stage. The difference between the 2 schemes proposed for the sliding-mode fault-tolerant control is that the second one includes a separate control allocation module, which makes it easier to apply actuator constraints to the problem. Moreover, it will be shown that, with the second scheme, we can deal with actuator faults or even failures without controller reconfiguration. We further discuss the advantages and disadvantages of the 2 schemes in more details. The effectiveness of the proposed schemes are illustrated with numerical examples

Fault tolerant control using sliding modes with on-line control allocation

Journal ArticleThis paper proposes an on-line sliding mode control allocation scheme for fault tolerant control. The effectiveness level of the actuators is used by the control allocation scheme to redistribute the control signals to the remaining actuators when a fault or failure occurs. The paper provides an analysis of the sliding mode control allocation scheme and determines the nonlinear gain required to maintain sliding. The on-line sliding mode control allocation scheme shows that faults and even certain total actuator failures can be handled directly without reconfiguring the controller. The simulation results show good performance when tested on different fault and failure scenarios. © 2008 Elsevier Ltd. All rights reserved.EPSR

Design and analysis of an integral sliding mode fault-tolerant control scheme

This is the author's version of an artiucle subseqiently published in IEEE Transactions on Automatic Control. The definitive published version is available via doi: 10.1109/TAC.2011.2180090A novel scheme for fault-tolerant control is proposed in this paper, in which integral sliding mode ideas are incorporated with control allocation to cope with the total failure of certain actuators, under the assumption that redundancy is available in the system. The proposed scheme uses the effectiveness level of the actuators to redistribute the control signals to healthy actuators without reconfiguring the controller. The effectiveness of the proposed scheme against faults or failures is tested in simulation based on a large transport aircraft model. © 2011 IEEE

A fault tolerant control allocation scheme with output integral sliding modes

Copyright © 2013 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Automatica. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Automatica Vol. 49 (2013), DOI: 10.1016/j.automatica.2013.02.043In this paper a new fault tolerant control scheme is proposed, where only measured system outputs are assumed to be available. The scheme ensures closed-loop stability throughout the entire closed-loop response of the system even in the presence of certain actuator faults/failures. This is accomplished by incorporating ideas of integral sliding modes, unknown input observers and a fixed control allocation scheme. A rigorous closed-loop stability analysis is undertaken, and in fact a convex representation of the problem is created in order to synthesize the controller and observer gains. The efficacy of the proposed scheme is tested by applying it to a benchmark civil aircraft model

Controllability and Design of Unmanned Multirotor Aircraft Robust to Rotor Failure

A new design method for multi-rotor aircraft with distributed electric propulsion is presented to ensure a property of robustness against rotor failure from the control perspective. Based on the concept of null controllability, a quality measure is derived to evaluate and quantify the performance of a given design with the consideration of rotor failure. An optimization problem whose cost function is based on the quality measure is formulated and its optimal solution identifies a set of optimal design parameters that maximizes an aircraft’s ability to control its attitude and hence its position. The effectiveness of the proposed design procedure is validated through the results of experimentation with the Autonomous Flying Ambulance model being developed at Caltech’s Center for Autonomous Systems and Technologies

Active Fault Tolerant Control of MuPAL-a Using Sliding Modes

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordThis paper proposes a simple adaptive sliding mode observer to estimate the effectiveness level of actuators and uses this information as part of an active fault tolerant controller. These observers create an FDI scheme at a 'local' level and the effectiveness estimates are used to drive the online control allocation component in the overall scheme. The approach has been tested on a model of JAXA's MuPAL-a experimental aircraft. The nonlinear simulation results, in fault free and faulty situations, show the efficacy of the scheme. Furthermore, the proposed sliding mode observer has been tested offline using previously collected MuPAL-a flight data and good results are achieved.European Union Horizon 2020Japan New Energy and Industrial Technology Development Organizatio

Integral sliding mode fault tolerant control allocation for a class of affine nonlinear system

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.This paper develops novel fault tolerant integral sliding mode control allocation schemes for a class of over-actuated affine nonlinear system. The proposed schemes rely on an existing baseline controller and the objective is to retain the nominal (fault-free) closed-loop performance in the face of actuator faults/failures by effectively utilizing actuator redundancy. The online control allocation reroutes the control effort to the healthy actuators using knowledge of the actuator effectiveness level estimates. One of the proposed schemes is tested in simulation using a well known high fidelity model of a large civil transport aircraft (B747) from the literature. Good simulation results show the efficacy of the scheme