Search

In this paper, the problems of sensor fault estimation and accommodation for discrete-time dynamic systems are investigated. Firstly, an augmented system is constructed where the sensor fault variable is added to the state vector. Then based on the descriptor observer technique, the efficient conditions of fault estimation under the disturbance and without the disturbance are both obtained. Finally, a static output feedback controller is employed to tolerate the sensor fault such that the closed-loop system is asymptotically stable. At last, a numerical example is provided to illustrate the proposed technique.

This paper is concerned with the fault estimation and accommodation problem of switched systems via a new concept named “generalized separation principle”, which is principles of separation of three elements: individual observer, individual control, and switching law. Based on such a concept, sufficient fault recoverability conditions are established, fault estimation and accommodation design procedures are also given.

In this paper, a fault-tolerant control scheme for two physically linked two wheel drive (2WD) mobile robots with multiple and simultaneous actuator faults is proposed. The kinematic and dynamic models are first presented. A kinematic control law is designed, based on which, a dynamic control law is investigated. By applying the proposed dynamic control signal, the desired system stability and tracking properties are ensured. Simulation results are finally presented to verify the effectiveness of the developed fault-tolerant control scheme.

This paper investigates attitude stabilization problem of three-inline array tethered spacecraft formation. A simplified nonlinear model around the equilibrium point is presented under which a novel decentralized formation control scheme is proposed, where the coupling among spacecraft is fully considered by using interconnected system approach and plays an important role in the control design. It is shown that the formation stability can be achieved by using both individual control laws of spacecraft and coupling effects. The issues of decentralized fault tolerant control and fault propagation behaviors are further addressed. Simulation results show the effectiveness of the proposed method and the performance improvement by using the new control scheme instead of a distributed control.

This paper investigates the path tracking problem for an electric vehicle which has four electromechanical wheel systems under normal and faulty conditions. With considering wheel slip constraints and certain actuator faults, a passive fault-tolerant controller based on variable structure control is developed to maintain the system stability and guarantee the acceptable tracking performance. Then based on the designed controller, a simple active fault diagnosis approach is introduced for this typical over-actuated system to isolate and evaluate faults more precisely. With the diagnosed information, an accommodated fault tolerant controller is designed to maintain the tracking performance. Finally, simulations of traction engine multiple faults are conducted to illustrate the proposed method.

This paper considers fault tolerant attitude control problem of spacecraft under intermittent faults that occur in the control processor. A novel control framework based on multiple redundant control processors is provided, and a state-dependent switching law among these processors is proposed to stabilize the attitude dynamics without requiring control reconfiguration in each control processor when faults occur. Moreover, a probability-based method is provided to find the minimal number of control processors that are needed for attitude stabilization. Simulation results show the efficiency of the proposed methods.

Structural analysis is a powerful tool for early determination of detectability/isolability possibilities. It is shown how different levels of knowledge about faults can be incorporated in a structural fault-isolability analysis and how they result in different isolability properties. The results are evaluated on the DAMADICS valve benchmark model. It is also shown how to determine which faults in the benchmark that need further modeling to get desired isolability properties of the diagnosis system.