Zetao Li

Parameter intervals used for fault isolation in non-linear dynamic systems

Parameter intervals can be used to solve fault isolation problems. The parameter interval-based fault isolation method has good speed and can provide an estimate of the faulty parameter. In this paper, a parameter interval-based fault isolation method for non-linear dynamic systems is presented.

A novel energy-efficient data gathering algorithm for wireless sensor networks

Data gathering is one of the most important operations in wireless sensor networks. Since the nodes operate on limited power, it is a critical task to design an energy-efficient data gathering algorithm. In this paper, we propose an energy-efficient data gathering algorithm (EDGA) in which the network is grouped into clusters (each with a clusterhead) and the nodes form chains in each cluster. Firstly, a node, according to support degree from neighbors and its remaining energy, independently makes its decision to compete for becoming a clusterhead. Furthermore, the clusterhead adapts ant colony optimization (ACO) to schedule access sequence of nodes (chain). Simulation results show that EDGA can reduce energy consumption efficiently and prolong the network lifetime when compared with the conventional clustering method.

Application of a model based fault isolation method for nonlinear dynamic systems

The goal in many fault isolation schemes is to decrease the isolation and identification time. The mathematical model of the physical system is the information available before hand. This paper presents the application of a nonlinear model based adaptive observer design to help in the isolation of faults in parameters of nonlinear dynamic systems. The method uses parameter partition and it fits many kinds of nonlinear dynamic systems. One important assumption is the monotonicity of the nonlinear function. The simulations results of an alcoholic fermentation model are used to demonstrate the method validity.

Actuator fault detection and isolation via input reconstruction: Application to intensified heat exchanger reactor

This paper proposes a left invertible cascade nonlinear system structure with a dynamic inversion based input reconstruction laws, forming a novel model-based actuator fault detection and isolation (FDI) algorithm. Actuator is viewed as subsystem connected with the process subsystem in series, thus identifying actuator faults with advancing FDI algorithm in the subsystem whose outputs are assumed unmeasured. The left invertibility of individual subsystem is required for ensuring faults occurred in actuator subsystem can be transmitted to the process subsystem uniquely, and for reconstructing process inputs, also actuator outputs, from measured process outputs. Effectiveness of the proposed approach is demonstrated on an intensified HEX reactor developed by the Laboratoire de Génie Chimique (LGC -Toulouse, France).

Research on fault detection of tennessee eastman process based on PCA

Principal component analysis (PCA) method used in the fault diagnosis of industrial process is the most famous one of multivariate statistical methods. It concerns using few linear combinations of the set of process variables to explain the whole process operation state, and to detect the process fault. In this paper, the PCA method has been applied in Tennessee Eastman (TE) chemical process model. The simulation results show that PCA method can detect the fault quickly and effectively in some complex nonlinear chemical process.

Design of passive fault tolerant control of a process system

Fault tolerant control strategies are classified into active tolerant control and passive tolerant control. When an efficient fault diagnosis procedure is difficult to be obtained, a passive tolerant control strategy is a realistic choice. This paper introduces an example of passive tolerant control system design which take into account the priori knowledge of the possible system faults. The simulation result shows the effectiveness of the passive tolerant control strategy.

Actuator gain fault diagnosis for heat-exchanger/reactor

This paper deals with fault detection and diagnosis (FDD) of actuator gain occurring abruptly and incipiently for intensified continuous heat-exchanger/ reactor, meanwhile, occasion whereby system is subjected to either model uncertainties or external disturbance is discussed. The proposed algorithm is based on adaptive updating rules which not only decreases the computational burden, but also gives significantly better parameter identification and robustness properties. Effectiveness of the proposed approach is demonstrated on an intensified HEX reactor developed by the Laboratoire de Génie Chimique (LGC-Toulouse, France.

On the integration of actuator fault detection and isolation in model based fault diagnosis

The main goal of the Fault Detection and Isolation (FDI) is to effectively detect faults and accurately isolate them to a failed component in the shortest time possible. This capability leads to reduction in diagnostic time, therefore, increased the system availability. Also, a good inherent diagnostic of a system enhances the operating system confidence. This paper proposes a new formulation of the linear system to obtain the conditions of the actuator fault detection and isolation. We consider the actuator as a dynamic subsystem connected with the process subystem in a cascade manner and we look for the fault detectability and isolability problems. An example illustrates the performances of such interval observer approach for simple actuator fault diagnosis. In fact two mathematical models are given: a simple model for the actuator subsystem and a continuous time state-space description for the process subsystem of a speed governor for large diesel engines.

Multi-parameters fault isolation using vertex algorithm

Parameter interval calculation has been used for fault isolation, but the verification of multi-parameter interval is difficult for multi-parameter fault. To check a multi-parameter interval whether contains the parameter vector value of the faulty system, the vertex algorithm can be used when the isotonic condition is satisfied, and then the calculation is greatly simplified. For the systems which does not satisfy isotonic condition, the vertex algorithm can also be used by means of observer technique when the required system states are measurable. This paper presents the fault isolation method using vertex algorithm for multi-parameter fault.

Study on the parameters estimation based on interval observer

The method using interval observers to estimate parameters have been verified in linear system and simple nonlinear cooperative system (elements of Jacobian matrix on the non-diagonal are non-negative). We can see the concept about cooperative system in references, but it has some limitations for reality system. This paper tries to use interval observer method for more general nonlinear system which is not a cooperative system. The Jacobian matrix of the observer can meet the condition of cooperative system by properly choosing the gain of the observer, hence the observer becomes a monotonic observer. By using this method, one can determine whether the parameter interval contains the value of the system parameter. The feasibility of this idea is illustrated by the simulation example using a nonlinear dynamic system model.