Passive Fault Tolerant Control Research Articles

A novel semi-active control strategy based on the quantitative feedback theory for a vehicle suspension system with magneto-rheological damper saturation

This paper presents a robust controller for a semi-active suspension system with actuator saturation. It addresses the vehicle vibration attenuation problem under two cases: (i) without actuator fault (magneto-rheological (MR) damper) and (ii) with base oil leakage in MR damper. The solution is obtained using the quantitative feedback theory (QFT) design. The actuator (MR damper) dynamics is well approximated by a first order model with an uncertain time constant. The superior performance of the proposed QFT controller, for fault free case, is compared with the sky-hook, H∞ control and passive suspension in time as well as in frequency domains. To address the system with faulty MR damper, a multiple model approach based QFT design is then proposed. The multiplicative type fault is considered as an MR damper fault and the faulty damper output delivering capability is then reduced by 80% to 75% due to the oil leakage in the damper. The proposed idea is centered on dividing the large uncertain system into a set of small uncertain linear system and then design the QFT controller corresponding to each of the generated linear models. The global controller is formulated by aggregating the local controller with the gap metric based weights. This new approach produces the similar performance as that of the passive fault tolerant control (FTC)-QFT design with less control effort. Extensive comparative simulations are provided to show the efficacy of the proposed method over passive FTC-QFT, passive FTC-H∞ design and sky-hook control.

Passive fault-tolerant control for vehicle active suspension system based on H2/H∞ approach

In this paper, a robust passive fault-tolerant control (RPFTC) strategy based on H2/H∞ approach and an integral sliding mode passive fault tolerant control (ISMPFTC) strategy based on H2/H∞ approach for vehicle active suspension are presented with considering model uncertainties, loss of actuator effectiveness and time-domain hard constraints of the suspension system. H∞ performance index less than γ and H2 performance index is minimized as the design objective, avoid choosing weighting coefficient. The half-car model is taken as an example, the robust passive fault-tolerant controller and the integral sliding mode passive fault tolerant control law is designed respectively. Three different fault modes are selected. And then compare and analyze the control effect of vertical acceleration of the vehicle body and pitch angular acceleration of passive suspension control, robust passive fault tolerant control and integral sliding mode passive fault tolerant control to verify the feasibility and effectiveness of passive fault tolerant control algorithm of active suspension. The studies we have performed indicated that the passive fault tolerant control strategy of the active suspension can improve the ride comfort of the suspension system.

Robust fault-tolerant controller design for aerodynamic load simulator

Load simulator is one of the main mechanisms for stability and performance evaluation of the rotational/translational actuators in the laboratory. The movement of (under testing) actuator generates a large disturbance on the load simulator known as “extraneous torque”. Elimination of this large surplus disturbance is the main concern of the dynamic load simulator design. The faults are unavoidable events in system operation. Sensor or actuator faults frequently occur in flight systems. The design method based on Quantitative Feedback Theory (QFT) can be used as a passive Fault-Tolerant Control (FTC) of the plants with sensor or actuator faults. In this paper, a QFT-FTC is proposed for the electric load simulator (ELS) in presence of sensor and actuator faults. For this purpose, a particular type of faults is used, which the sensor and actuator faults are considered as semi-deterministic jumps that occurring at random intervals with random amplitudes. In the first step, the faults are converted to parameter uncertainties and disturbance is transferred to the input and output of the plant. Then, a QFT controller is designed for this uncertain plant. Proposed QFT-FTC attenuates the large disturbance even if the control effort is limited. Under these circumstances, an adequate bandwidth is achieved. Furthermore, semi-deterministic jumping faults on sensor and actuator are applied during the simulations and high robust tracking performance is obtained in presence of the saturated control. Compared to H-infinity Controller, the proposed controller has a simpler structure and its tracking performance is better than H-infinity method.

Experimental Investigation of Passive Fault Tolerant Control for Induction Machine Using Sliding Mode Approach

AbstractThis paper presents a passive fault tolerant control approach dedicated to stator inter‐turn short‐circuit fault of an induction machine. This control is based on sliding mode strategy and is implemented for validation on real‐time data acquisition and control platform. The proposed work highlights the integral sliding mode controller benefits during healthy and faulty operations. It can make the induction machine outputs to track their desired reference signals in finite‐time and allows to obtain a better dynamic response performances even in presence of fault. Moreover to avoid the use of a flux sensor, a second order sliding mode observer is used to estimate the rotor flux. Since the used observer converges in finite time, the closed‐loop stability of the proposed system (controller+observer) is proved using the Lyapunov stability theorem. Experimental results are conducted for squirrel cage induction machine to highlight the efficiency and applicability of the proposed fault tolerant control.

Nonsingular Terminal Sliding Mode Based Passive Fault-Tolerant Control of a 3-DOF Helicopter System

In this paper, a new passive fault-tolerant controller for 3-DOF helicopter is designed. The 3-DOF helicopter is an underactuated system, which has three degrees of freedom, however, only two control inputs. Here two virtual components related to only one control input are introduced, which when combined with other control input decouple the 3-DOF helicopter system into three separate subsystems. For each subsystem, a passive fault-tolerant controller is constructed based on nonsingular terminal sliding mode method, achieving attitude angle tracking. Finally, simulations are conducted to verify the effectiveness of the proposed scheme.

Passive Fault Tolerant Lateral Controller Design For an UAV

Abstract In this study a passive lateral fault tolerant controller for an UAV is designed using dynamic inversion (DI) method and robust integral of the signum of the error (RISE) techniques. The details of the methods are summarized. As the reference model of the tracking controller, UAV controlled by feedback type controller is used and the control method used for this design is explained. The loss in control effectiveness is modeled as changes in the control distribution matrix. Simulations are made to show the effectiveness of the passive fault tolerant controller in maintaining the lateral control in case of actuator effectiveness loss.

Overview of fault-tolerant control methods for discrete event systems

Fault-tolerant control (FTC) is an active research field promoted by the increased demand on reliability, availability and safety of manufacturing systems. In this paper, an overview of the approaches for FTC of discrete event systems is presented. The focus is on automata and Petri nets, as they are widely used frameworks. The active and passive FTC approaches are presented and their application to different modes of the fault process is shown.

Passive Fault-Tolerant Control of an Underactuated Re-Entry Capsule

The design of a passive fault-tolerant control for an underactuated re-entry capsule is considered in this paper; however, the control input of the capsule is failed. At first, kinematics and dynamics of the capsule are studied and modeled, and adaptive control law is used to design a passive controller for the control of the capsule. The guidance law for the capsule is designed based on the guidance law which is used in Apollo. A simulation is performed based on Apollo capsule in order to assess the controller. The result shows good control authority of the controller in the presence of failure in roll and yaw control channels. It is also shown that the guidance law is not credible in the presence of yaw channel input failure.

Passive fault tolerant perfect tracking with additive faults

An architecture of a control system with additive faults is given, with a controller consisting of three blocks, and a problem of fault-tolerant (FT) perfect tracking is formulated. It is shown that there is a passive FT controller such that its performance is not worse than the performance of the nominal controller, while in presence of faults, it practically rejects the faults, on expense of a big magnitude of the control in times when faults appear. A numerical simulation is given.

Fault-Tolerant Track Control of Hypersonic Vehicle Based on Fast Terminal Sliding Mode

In this paper, the track control problem of hypersonic a vehicle with modeling uncertainties, external disturbance, and multifault is studied and analyzed. First, a fault model of a second-order system including disturbance is established by introducing auxiliary error variables on the basis of feedback linearization for a longitudinal model of the hypersonic vehicle. Second, for a fault-free actuator and system model with unknown upper bound disturbance, a fast adaptive terminal sliding mode controller is designed, which ensures the sliding mode manifold is finite-time stable. To solve the multifault problem of actuator, based on the passive fault-tolerant control method, a fast adaptive terminal sliding mode fault-tolerant controller is designed, which guarantees that the system state is finite-time stabile in the event of actuator failure. The controller adopts two adaptive algorithms to estimate the unknown fault information and system disturbance information. Finally, a rigorous proof using Lyapunov theory is given for the stability of the designed controllers. Numerical simulation is run for the longitudinal nonlinear dynamic model of a hypersonic vehicle and simulation results prove the effectiveness of the two designed controllers.

Passive actuator fault tolerant control for a class of MIMO nonlinear systems with uncertainties

ABSTRACTFault tolerant control of affine class of multi-input multi-output (MIMO) nonlinear systems has not received considerable attention of researchers compared to other class of nonlinear systems. Therefore, this paper proposes an adaptive passive fault tolerant control method for actuator faults of affine class of MIMO nonlinear systems with uncertainties using sliding mode control . The actuator fault is represented by a multiplicative factor of the control signal which reflects the loss of actuator effectiveness. The design of the controller is based on the assumption that the maximum loss level of the actuator effectiveness is known. Furthermore, since the proposed controller is adaptive, it does not require any a-priori knowledge of the uncertainty bounds. The closed-loop stability conditions of the controller are derived based on Lyapunov theory. The effectiveness of the proposed controller is demonstrated considering two examples: a two degree of freedom helicopter and a two-link robot manipulator and has been found to be satisfactory.

Passive Fault-tolerant Cooperative Control in an Offshore Wind Farm

The rapid growth in size and capacity of wind turbines together with harsh climate conditions and limited accessibility in offshore regions all result in higher failure rates and increased maintenance requirements and costs. Such difficulties motivate the use of advanced fault detection and diagnosis as well as fault-tolerant control schemes in wind farms to improve their reliability and availability. Given the importance of this issue, the current paper employs a fuzzy model reference adaptive control approach in a cooperative framework that is oriented to the design and development of a novel passive fault-tolerant cooperative control scheme in a wind farm. This scheme handles decreased power generation faults in a wind farm caused by turbine blade erosion and debris buildup on the blades over time. The effectiveness and performance of the proposed scheme is demonstrated by a series of simulations on an advanced large off-shore wind farm benchmark model.

Interval observer framework for fault-tolerant control of linear parameter-varying systems

ABSTRACTThis paper addresses the problem of passive fault-tolerant control for linear parameter-varying systems subject to actuator faults. The FTC, based on a linear state feedback, is designed to compensate the impact of actuator faults on system performance by stabilising the closed-loop system using interval observers. The design of interval observers is based on the discrete-time Luenberger observer structure, where uncertainties and faults with known bounds are considered. Sufficient conditions for the existence of the proposed observer are explicitly provided. Simulation results are presented to show the effectiveness of the proposed approach.

Hybrid Active-Passive Robust Fault-Tolerant Control of Event-Triggered Nonlinear NCS

In this paper, the authors aimed to analyze uncertain nonlinear networked control systems (NCS) under discrete event-triggered communication scheme (DETCS), in which an integrated design methodology between robust fault detection observer and active fault-tolerant controller is proposed. Moreover, the problem of hybrid active–passive robust fault-tolerant control, which integrated passive fault-tolerant control, fault detection, and controller reconstruction, is researched. In consideration of the impact of uncertainties and network-induced delay on system performance, a new class of uncertain nonlinear NCS fault model is established based on T-S fuzzy model. By employing Lyapunov stability theory,H∞control theory, and linear matrix inequality method, the fault detection observer and hybrid fault-tolerant controller are both appropriately designed. In addition, the sufficient condition that guaranteed the asymptotically robust stability of nonlinear NCS against any actuator failures is deduced. Finally, a numerical simulation is provided to show the effectiveness of the proposed methods.

Passive fault tolerant control allocation for small unmanned underwater vehicle

ABSTRACTThe paper presents methods of control allocation in a multi-thruster propulsion system of a small torpedo-shaped underwater vehicle. It concentrates on finding an optimal thrust distribution among thrusters for demanded values of propulsive forces and moments. The approach is directed towards minimisation of energy expenditures necessary to obtain required control. Special attention is paid to the unconstrained thrust allocation for both a faultless and faulty work of the propulsion system. The developed algorithms are designed to be modular, interchangeable and highly computationally efficient. Illustrative examples are inserted to demonstrate correctness and simplicity of proposed thrust allocation methods.

Improved adaptive fuzzy sliding mode controller for robust fault tolerant of a Quadrotor

In this paper, a model for a Quadrotor helicopter has been considered when a fault has been occurred in its actuators. The sliding mode control technique has been utilized as one of a robust passive fault tolerant control methods to control the Quadrotor’s attitude. An adaptive fuzzy system, as a compensator has been used to compensate the estimation error of nonlinear functions and faulty parts. Although increasing the adaptation rate enhances the responding speed, it is accompanied by closed loop system instability. In order to avoid instability and to increase the robustness of the closed loop system, in this paper, a new parallel fuzzy system has been proposed along with a main fuzzy system. The adaptation rules of the main and parallel fuzzy systems were extracted from Lyapunov’s stability theory. During the numerical simulation, the efficiency of the proposed method has been shown against actuator faults.

Attitude control of an underactuated spacecraft using quaternion feedback regulator and tube-based MPC

Feasibility of achieving 3-axis stabilization of an asymmetric spacecraft for cases where there is no control available in one axis (underactuated spacecraft) is explored in this paper. A novel control design methodology is presented which can stabilize the underactuated spacecraft and steer it to the origin. A passive fault tolerant control (FTC) is defined which controls and maintains the attitude of the spacecraft near the desired point in presence of uncertainties, disturbances, control constraints and actuator faults. Considering the general conditions of the underactuated spacecraft, a hybrid controller combining a quaternion feedback regulator (QFR) with a tube-based model predictive controller (MPC) is developed based on the nonlinear kinematic and dynamic equations of the spacecraft motion. The hybrid controller is composed of two control stages. At the first stage, QFR decreases the angular velocities and brings the state vector to an acceptable region for the next stage. Then, tube-based MPC solves two optimal control problems, a standard problem for the nominal system to define a central guide path, and an ancillary problem to steer the state vector towards the central path with semi-optimal control effort. Numerical simulation results obtained for the underactuated spacecraft merely indicate effectiveness of the proposed attitude control method.

Active Fault-Tolerant Control for Electric Vehicles With Independently Driven Rear In-Wheel Motors Against Certain Actuator Faults

An active fault-tolerant control (AFTC) system is proposed in this paper for electric vehicles with independently driven in-wheel motors (IWMs). It comprises a baseline controller, a set of reconfigurable controllers, a fault detection and diagnosis (FDD) mechanism, and a decision mechanism. The baseline controller, which is actually a passive fault-tolerant controller, is applied to accommodate actuator faults and stabilize the faulty vehicle when the actuator fault occurs. After the fault is detected and estimated by the FDD mechanism, a proper reconfigurable controller is switched ON to achieve optimal postfault performance. Taking advantage of the robust gain-scheduling algorithm, the loss-of-effectiveness and additive faults of the IWMs can be accommodated by the baseline controller, and the estimation error of the FDD mechanism can be tolerated by the reconfigurable controllers. The results of simulations in CarSim and vehicle experimental tests show the effectiveness of this AFTC system in dealing with certain IWM faults.

Acceleration-based fault-tolerant control design of offshore fixed wind turbines

Wind turbines (WTs) are basically controlled by varying the generator load torque (with the so-called torque control) and the blade pitch angles (with the so-called pitch control) based on measurement of the generator shaft speed. These two controllers unitedly work to satisfy the control objectives, and it is crucial that they are tolerant to possible faults in the WT system. Passive fault-tolerant control comprises the design of robust controllers against disturbances and uncertainties. This enables the controller to counteract the effect of a fault without requiring reconfiguration or fault detection. In this regard, the main contribution of this paper is to propose new control techniques that not only provide fault tolerance capabilities to the WT system but also improve the overall performance of the system in both fault-free and faulty conditions. Coupling nonlinear aero-hydro-servo-elastic simulations of an offshore WT with jacket platform is carried out for several pitch actuator faults. The jacket platform motions and structural loads caused by fault events with the proposed controllers are compared with loads encountered during normal operation and with respect to a well-known baseline controller in the literature. The proposed controllers are based in the super-twisting algorithm by using feedback of the generator shaft speed as well as the fore-aft and side-to-side acceleration signals of the WT tower.

Passive Fault Tolerant Control of PEMFC air feeding system

In this paper, a Passive Fault Tolerant Control strategy dedicated to air feeding system fault based on an auto-tuning PID regulator is designed and implemented on a real fuel cell test bench. The present work compares the auto-tuning PID strategy performance to classical PID controller and highlights its benefits during faulty operation. Experimental results demonstrate the effectiveness of the proposed approach to regulate oxygen stoichiometry in real-time operation while maintaining a proper system performance under faulty situations. Unlike the classical PID controller, the proposed Passive Fault Tolerant Control System shows highly satisfactory performance in terms of setpoint tracking accuracy and disturbances rejection capability during faulty operations.