Nadia Zanzouri

Active Fault Tolerant Control Based on Bond Graph Approach

This paper proposes a structural fault recoverability analysis using the bond graph (BG) approach. Indeed, this tool enables structural analysis for diagnosis and fault tolerant control (FTC). For the FTC, we propose an approach based on the inverse control using the inverse BG. The fault tolerant control method is also compared with another approach. Finally, simulation results are presented to show the performance of the proposed approach.

Robust Fault Diagnosis Observer of Dynamical Systems Modelled by Bond Graph Approach

Abstract This paper proposes a robust diagnosis observer of dynamical systems modeled by Bond Graph approach. The observer design is achieved by using graphical methods taking advantage of structural properties of the bond graph model. The fault indicators are generated in the presence of parameter uncertainties. Simulation results are used to show the dynamic behavior of system variables and to evaluate the performance of the observer for fault diagnosis.

Active fault tolerant control of hybrid system based on MLD model

This paper deals with the Mixed Logical Dynamical (MLD) approach. It allows to model the hybrid systems involved continuous, discrete dynamics and constraints. The resultant system is well-posed for Model Predictive Control (MPC) that is used as control strategy for the system. An active Fault Tolerant control is proposed. This approach is illustrated by a tank system. Simulations are performed using the Hysdel compiler to show the efficiently of this formalism and the fault tolerant MPC control.

Distinguishability and similarity between modes in hybrid system monitoring

The general principle of model-based Fault Detection and Isolation (FDI) algorithms aims to compare the expected behavior of the system, given by a model, with its actual behavior, known through on-line observations.

Robust diagnosis for hybrid dynamical systems

The aim of this paper is to propose a hybrid observer design for linear Hybrid Dynamical systems (HDS) modeled via hybrid automata. In addition, the structure of the proposed observers is based on a discrete observer and a continuous observer on interaction. The discrete observer reconstructs the discrete mode and detects discrete faults. Once, the active mode is obtained, the continuous observer which is synthesized around a DOS (Dedicated Observer) Scheme to generate structured residuals which locate sensor faults. The observer based method is designing with LMI (linear Matrix Inequalities) formulation technique. A robust evaluation method based on the residuals norm (errors estimation) is used to detect the noisy active mode.

Fault-Tolerant Model Predictive Control of Hybrid Systems

paper, focuses on model predictive control (MPC) problem with fault-tolerance capabilities is formulated within the hybrid systems framework In particular Mixed Logical Dynamical (MLD) approach is considered. It allows to model the hybrid systems involved continuous, discrete dynamics and constraints. The changes or the switches which may appear over such dynamics are modeled by using the auxiliary variables taking into account the interconnections. In this work, we proposed a reconfiguration control approach based on Model Predictive Control (MPC) framework. A fault MLD model is also proposed. The main contribution of this paper consists in the investigation of a new method for fault tolerant control used the MLD model. The proposed formulation is illustrated by considering a two tank system benchmark.

Model Predictive Control of hybrid systems with discrete and continuous inputs

This paper proposes and discusses a model predictive control approach to hybrid system, with discrete and continuous inputs. The hybrid model of two tank system is translated into mixed logical dynamical (MLD) form, which considering all constraints in the physical plant, such as maximum (flow in the pomp) and maximum level in the tank. The resultant system is well-posed for Model Predictive Control (MPC) that is used as control strategy for the system. Simulations are performed using the Hysdel compiler to illustrate the efficiently of this formalism and prove the influence of increasing the prediction horizon.

Online implementation of inequality constraints monitoring in dynamical systems

This paper deals with fault detection in dynamical systems where the state variables evolutions are constrained by inequality constraints. The latter corresponds either to physical limitations or to safety specification. Two classical residual generation approaches are studied, namely, parity space and unknown input observer approaches, and are extended to monitor the inequality constraints. A practical implementation on a real process is performed and permits to validate the relevance of the proposed methods.

Behavior Graphs for Hybrid Systems Monitoring

Hybrid Dynamical Systems (HDS) constitute a wide class of common industrial applications, where the behavior is determined by the interaction between continuous and discrete dynamics, i.e. behavioral modes succession. The general principle of model-based Fault Detection and Isolation (FDI) algorithms is to compare the expected behavior of the system, given by a model, with its actual behavior, known through on-line observations. Faults in HDS may corrupt the two dynamics. In that paper, we propose to limit the set of possible mode candidates by using a priori information on the discrete evolution under normal and faulty hypothesis. Two kinds of graphs are derived from the initial hybrid model, namely Normal Behavior Graphs (NBG), Faulty Behavior Graphs (FBG). Using these graphs allows us not only to identify efficiently the actual mode but also to directly interpret (diagnose) the discrete faulty evolution in terms of faults. The whole FDI methodology is described and applied to a two tanks system example.

Cement Water Treatment Process Modeling Hybrid Bond Graph: Modeling and Experimental Validation

This paper propose an Hybrid Bond Graph modeling of the cement water treatment process. The description of this complex process highlights the diversity of physical phenomena which leads to the interaction between several domains such as hydraulic, chemical, electrical, etc. An experimental characterization of the system is performed in order to assess the validated bond graph model of the studied process. The simulation results obtained from this elaborated model reveal a significant conformity compared to the experimental results.