Reconfigurable Control System Design Research Articles

Modular robust reconfigurable flight control system design for an overactuated aircraft

In this study a modular approach to the robust reconfigurable flight control system design for an overactuated aircraft is proposed. The structure of the proposed scheme consists of three parts: a backstepping controller module, a robust control allocator and an online actuator effectiveness estimator. Firstly, the backstepping control law is developed for the strict feedback form of an Aero-Data Model in Research Environment aircraft to produce the desired commands. Furthermore, a novel robust optimisation-based control allocation algorithm is proposed to distribute the commands among redundant actuators with the consideration of control effectiveness uncertainties. Lastly, the control effectiveness factors are introduced to denote the healthiness of the actuators, and the least trimming squares-based estimator is designed for online estimation of the actuator effectiveness. With the proposed scheme, good tracking performance, robustness and reconfigurable capability are achieved. Evaluation of the overall system is accomplished by numerical simulation with various conditions, including adverse scenarios where actuator failures occur. The results show the effectiveness of the proposed scheme.

Reconfigurable control system design using eigenstructure assignment: static, dynamic and robust approaches

New approaches to design static and dynamical reconfigurable control systems are proposed based on the eigenstructure assignment techniques. The methods can recover the nominal closed-loop performance after a fault occurrence in the system, in the state and output feedback designs. These methods are capable of dealing with order-reduction problems that may occur in an after-fault system. The problem of robust reconfigurable controller design, which makes the after-fault closed-loop system insensitive as much as possible, to the parameter uncertainties of the after-fault model is considered. Steady state response of the after-fault system under the unit step input is recovered by the means of a reconfigurable feed-forward compensator. The methods guarantee the stability of the reconfigured closed-loop system in the case of output feedback. For the faulty situations, in which the order of the pre-fault and after-fault closed-loop systems are the same, sufficient regional pole assignment conditions for the reconfigured system are derived. Finally, simulation results are provided to show the effectiveness of the proposed methods for two aircraft models.

Active fault-tolerant control system against partial actuator failures

A novel approach for integrated fault detection, diagnosis and reconfigurable control systems design against actuator faults is proposed. The scheme is based on a two-stage adaptive Kalman filter for simultaneous state and fault parameter estimation, statistical decisions for fault detection, and activation of controller reconfiguration. Using the information from the fault detection and diagnosis scheme, the reconfigurable feedback controller is designed automatically based on an eigenstructure assignment technique. To eliminate the steady-state tracking error, a reconfigurable feedforward controller is also incorporated using a command generator tracker technique. The following fault types and input signals are considered: abrupt and incipient, single, multiple and consecutive faults, constant and arbitrarily varying reference inputs. The effectiveness and the superiority of the proposed approach are demonstrated using an aircraft example.

Novel approach to reconfigurable control systems design

Abssact: A novel linear model fdlowing appoach is proposed fa: rmfigurable contrd systems design, where a unique system configuration and design method are employed. It compares favOcaMy to the existing methods in that the design pw;edure is quite s t r a i g h t f i d and does not require intensive computation. Furthermure, it is shown that the new method provides better tracking perfopmane by significantly reducing the unstraints d pafea model following. It is also shown (hat even when perfect model fdlowing is not achieved, the pqmed approtach still minimizes the upper bound of the tracking m. The effectiveness d the new design approach is demonstrated in an aircraft longitudinal control system problem where it is compared to a recently proposed method.

Reconfigurable control system design via perfect model following

Abstract A novel model-following approach is developed to design reconfigurable control systems. The conventional state-space linear model-following approach to control is first re-examined with emphasis on the conditions for perfect model following and its application to reconfigurable control system design. New frequency domain necessary and sufficient conditions for perfect model following are then obtained and they are used to gain insight into the selection of the reference model and to develop a new design approach. This novel design approach yields fewer constraints on the reference model than before, and provides much greater flexibility in specifying the state trajectories of the impaired system.