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

Fault tolerant longitudinal aircraft control using non-linear integral sliding mode

Copyright © 2014 Institution of Engineering and Technology (IET)This study proposes a novel non-linear fault tolerant scheme for longitudinal control of an aircraft system, comprising an integral sliding mode control allocation scheme and a backstepping structure. In fault free conditions, the closed loop system is governed by the backstepping controller and the integral sliding mode control allocation scheme only influences the performance if faults/failures occur in the primary control surfaces. In this situation, the allocation scheme redistributes the control signals to the secondary control surfaces and the scheme is able to tolerate total failures in the primary actuator. A backstepping scheme taken from the existing literature is designed for flight path angle tracking (based on the non-linear equations of motion) and this is used as the underlying baseline controller in nominal conditions. The efficacy of the scheme is demonstrated using a high-fidelity aircraft benchmark model. Excellent results are obtained in the presence of plant/model uncertainty in both fault free and faulty conditions

A review of convex approaches for control, observation and safety of linear parameter varying and Takagi-Sugeno systems

This paper provides a review about the concept of convex systems based on Takagi-Sugeno, linear parameter varying (LPV) and quasi-LPV modeling. These paradigms are capable of hiding the nonlinearities by means of an equivalent description which uses a set of linear models interpolated by appropriately defined weighing functions. Convex systems have become very popular since they allow applying extended linear techniques based on linear matrix inequalities (LMIs) to complex nonlinear systems. This survey aims at providing the reader with a significant overview of the existing LMI-based techniques for convex systems in the fields of control, observation and safety. Firstly, a detailed review of stability, feedback, tracking and model predictive control (MPC) convex controllers is considered. Secondly, the problem of state estimation is addressed through the design of proportional, proportional-integral, unknown input and descriptor observers. Finally, safety of convex systems is discussed by describing popular techniques for fault diagnosis and fault tolerant control (FTC).Peer ReviewedPostprint (published version

Sliding Mode Propulsion Control Tests on a Motion Flight Simulator

This paper describes a fault-tolerant sliding-mode control allocation scheme capable of coping with the loss of all control surfaces resulting from a failure of the hydraulics system, during which time the scheme only uses the engines to control the aircraft. The paper presents tests of the scheme implemented on a six-degree-of-freedom motion research flight simulator at Delft University of Technology, using a realistic maneuver involving an emergency return to a near-landing condition on a runway in response to the failure. The simulator results show that not only does the controller provide high tracking performance during nominal fault-free conditions, this performance is also maintained after the total loss of all control surfaces. This shows the capability of the proposed sliding-mode control allocation scheme to achieve and maintain desired performance levels using only propulsion by redistributing the control signals to the engines when failures occur

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

Flight evaluation of an LPV sliding mode controller with online control allocation

Thiis is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordThis paper presents the results of flight tests of a fault tolerant sliding mode controller implemented on the Japan Aerospace Exploration Agency's Multi-Purpose Aviation Laboratory aircraft. These represent the first validation tests of a sliding mode control allocation scheme on a piloted flight test. In this scheme, information about the actuator faults is assumed to be estimated online from a fault detection unit and the available actuators are fully utilized in the presence of actuator faults, in an effort to retain nominal fault free performance. Specifically the flight tests results demonstrate good lateral-directional state tracking performance in the fault free case with no visible performance degradation in the presence of rudder and aileron faults. In fact, during the flight test, the evaluation pilot did not detect any degradation in manoeuvrability when the actuator faults occurred.European Union Horizon 2020Japan New Energy and Industrial Technology Development Organizatio

Development and Evaluation of an Integral Sliding Mode Fault Tolerant Control Scheme on the RECONFIGURE Benchmark

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.This paper describes the development, application and evaluation of a linear parameter-varying integral sliding mode control allocation scheme to the RECONFIGURE benchmark model to deal with an actuator failure/fault scenario. The proposed scheme has the capability to maintain close to nominal (fault free) load factor control performance in the face of elevator failures/faults, by including a retro-fitted integral sliding mode term and then re-routing (via control allocation) the augmented control signal to healthy elevators without reconfiguring the baseline controller. In order to mitigate any chattering appearing in the elevator demands, the retro-fitted signal is based on a super-twisting sliding mode structure. This produces a control signal which is continuous and does not have the discontinuous switching nature of traditional sliding mode schemes. The scheme is evaluated using an industrial Functional Engineering Simulator developed as part of the RECONFIGURE project. Monte-Carlo campaign results are shown to demonstrate the performance of the proposed scheme.The work in this paper is supported by EU-FP7 Grant (FP7-AAT-2012-314544): RECONFIGUR

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

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

Hardware-in-the-loop evaluation of an LPV sliding mode fixed control allocation scheme on the MuPAL-α research aircraft

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordThis paper develops a sliding mode fault tolerant control scheme based on an LPV system representation of the plant. The scheme involves a control allocation component, which is capable of fully utilizing the available actuators in the face of actuator faults. In this paper, information about the actuator faults is assumed not to be available and therefore a fixed control allocation structure is utilised in the event of faults. The proposed scheme is validated using the Japanese Aerospace Exploration Agency's Multi-Purpose Aviation Laboratory (MuPAL-α) research aircraft. This paper describes initial hardware-in-the-loop (HIL) tests which serve as a precursor to upcoming real flight tests. The validation results show good lateral-directional state tracking performance in the fault free case with no visible performance degradation in the presence of (aileron) faults. Successful HIL tests demonstrate the potential of the proposed scheme which will be flight tested later this year.European CommissionJapan New Energy and Industrial Technology Development Organizatio