Framework Of Active Fault-tolerant Control Research Articles

Data-Driven Output-Feedback Fault-Tolerant Compensation Control for Digital PID Control Systems With Unknown Dynamics

For digital proportional–integral–derivative control systems with unknown dynamics, the data-driven output-feedback fault-tolerant control (FTC) problem is studied in this paper. In a framework of active FTC, the issue of online recursive identification of the residual generator, the state observer, and the observability canonical form of the plant under consideration is addressed; the problem of reconfiguration of the data-driven fault-tolerant compensation controller with $L_2$ -gain properties is also dealt with by means of the above-obtained results, the prefilter and the Riccati equation related to $H_{\infty }$ control so as to accommodate faults and ensure tracking performance. The resulting fault-tolerant compensation control scheme is designed based on the closed-loop systems, and therefore has more practical significance than the existing FTC methodologies developed in terms of the open-loop systems. Finally, the effectiveness of the proposed FTC approach is validated by the speed control experiment on a dc motor.

Data-driven output-feedback fault-tolerant L2 control of unknown dynamic systems

This paper studies the data-driven output-feedback fault-tolerant L2-control problem for unknown dynamic systems. In a framework of active fault-tolerant control (FTC), three issues are addressed, including fault detection, controller reconfiguration for optimal guaranteed cost control, and tracking control. According to the data-driven form of observer-based residual generators, the system state is expressed in the form of the measured input–output data. On this basis, a model-free approach to L2 control of unknown linear time-invariant (LTI) discrete-time plants is given. To achieve tracking control, a design method for a pre-filter is also presented. With the aid of the aforementioned results and the input–output data-based time-varying value function approximation structure, a data-driven FTC scheme ensuring L2-gain properties is developed. To illustrate the effectiveness of the proposed methodology, two simulation examples are employed.

Data-driven output-feedback fault-tolerant control for unknown dynamic systems with faults changing system dynamics

This paper studies the data-driven output-feedback fault-tolerant control (FTC) problem for unknown dynamic systems with faults changing system dynamics. In a framework of active FTC, two basic issues are addressed: the fault detection employing only the measured input–output information; the controller reconfiguration to achieve optimal output-feedback control in the presence of multiple faults. To detect faults and write the system state via the input–output data, an approach to data-driven design of a residual generator with a full-rank transformation matrix is presented. An output-feedback approximate dynamic programming method is developed to solve the optimal control problem under the condition that the unknown linear time-invariant discrete-time plant has multiple outputs. According to the above results and the proposed input–output data-based value function approximation structure of time-varying plants, a model-free output-feedback FTC scheme considering optimal performance is given. Finally, two numerical examples and a practical example of a DC motor control system are used to demonstrate the effectiveness of the proposed methods.

Adaptive active fault-tolerant control of generic hypersonic flight vehicles

A theoretical framework of active fault-tolerant control is exploited for a hypersonic flight vehicle longitudinal dynamical system in cruise phase subject to actuator loss-of-effectiveness fault. First, an active fault detection scheme is proposed by designing a nonlinear fault detection observer for the faulty hypersonic flight vehicle model. A finite-time convergence fault-tolerant controller is proposed on the basis of combined back-stepping and sliding mode technology. Moreover, the adaptive law is developed to estimate the bound information of actuator efficiency factor. The fault-free controller is accomplished which guarantees the globally asymptotic output tracking and boundedness of the closed-loop system. Finally, numerical simulations in Simulation and Verification Platform are presented to illustrate that the proposed fault-tolerant control strategy is effective in providing satisfactory tracking performance and rejecting actuator faults in a climbing maneuver case.

Estimation and compensation of unknown disturbance in three-axis gyro-stabilized camera mount

Gyro-stabilized camera mounts are used to maintain and stabilize airborne remote sensing sensors, such as aerial cameras, light detection and ranging, and imaging spectrometers, for the purpose of isolating the line-of-sight of optical sensors from disturbing aircraft movements. However, it is difficult to achieve accurate line-of-sight pointing and even the system stability cannot be guaranteed due to the influences of unknown disturbance, such as mass imbalance, gimbal friction, aircraft attitude turbulence and model uncertainty. In order to realize high-precision disturbance rejection and robustness stability, a kind of compound control system is configured and designed in the framework of active fault-tolerant control. The basic idea of this paper is to handle the disturbance as a fault for disturbance compensation by applying online fault estimation and accommodation. Based on H∞ norm sub-optimization, a robust disturbance observer is designed to estimate the fault and then a fault compensator is employed to compensate for it. Based on an exosystem description, the internal model controllers are designed to achieve perfect tracking performance as well as robustness against model uncertainty. Finally, the experimental results demonstrate the effectiveness of the proposed compound control strategy in comparison with the traditional method.

Active fault tolerant control of piecewise affine systems with reference tracking and input constraints

SUMMARYAn active fault tolerant control (AFTC) method is proposed for discrete‐time piecewise affine (PWA) systems. Only actuator faults are considered. The AFTC framework contains a supervisory scheme, which selects a suitable controller in a set of controllers such that the stability and an acceptable performance of the faulty system are held. The design of the supervisory scheme is not considered here. The set of controllers is composed of a normal controller for the fault‐free case, an active fault detection and isolation controller for isolation and identification of the faults, and a set of passive fault tolerant controllers (PFTCs) modules designed to be robust against a set of actuator faults. In this research, the piecewise nonlinear model is approximated by a PWA system. The PFTCs are state feedback laws. Each one is robust against a fixed set of actuator faults and is able to track the reference signal while the control inputs are bounded. The PFTC problem is transformed into a feasibility problem of a set of LMIs. The method is applied on a large‐scale live‐stock ventilation model. Copyright © 2013 John Wiley & Sons, Ltd.