Efraín Alcorta-García

A Nonlinear Observer-Based Strategy for Aircraft Oscillatory Failure Detection: A380 Case Study

Robust and early detection of oscillatory failures in the electrical flight control system of an aircraft is a crucial issue. Oscillatory failures, if not detected and passivated in time, can lead to strong interactions with loads and aeroelasticity and may potentially lead to structural damages. A nonlinear observer-based solution to detect such failures with small amplitude at a very early stage is presented. The stability and convergence proofs are given and experimental results with real A380 flight data are presented.

Process control interface system for a distillation plant

This paper presents the development of a process control interface system (PCIS) for a distillation pilot plant that is based on the communication protocol called MODBUS. MODBUS communicates the computer (used as a control unit) with the process because it allows an efficient, flexible, and reliable system. The interface system is presented in an operator-friendly application, which has the capability to monitor the variables, manipulate actuators, and tune the controllers in the distillation process.

Observer-Based Supervision and Fault Detection of a FCC Unit Model Predictive Control System

Abstract This work is concerned with the design of a fault detection and isolation (FDI) system to monitor malfunctions in sensors and actuators of a fluid catalytic cracking (FCC) unit model predictive control (MPC) system. The control system is based on an infinite-horizon MPC algorithm. The fault detection scheme is developed based on two banks of robust observers, while the fault isolation task is done employing a structured residual approach. The models used in the control and in the FDI of the FCC unit are obtained by using subspace identification methods. The effectiveness of the proposed strategy is verified through numerical simulations carried out on a dynamical model of an industrial FCC unit under abrupt fault in its control devices.

Synchronization of Irregular Complex Networks with Chaotic Oscillators: Hamiltonian Systems Approach

Synchronization of multiple chaotic oscillators in Hamiltonian form is numerically studied and is achieved by appealingto complex systems theory [1-5]. The topology that we consider is the irregular coupled network. Two cases areconsidered: i) chaotic synchronization without master oscillator (where the final collective behaviour is a new chaoticstate) and ii) chaotic synchronization with master oscillator (where the final collective behaviour is imposed by thedynamics of the master oscillator to multiple slave oscillators). The Hysteretic and Rossler chaotic oscillators inHamiltonian form will be used as examples.

Intelligent Fault Diagnosis in Nonlinear Systems

Fault diagnosis in nonlinear systems is a challenging and very active research area. One of the difficulties to detect and isolate faults in nonlinear systems via observer-based methods is the design of a residual generator. In this work an integrated procedure combining conventional decoupling methods and Fuzzy Takagi-Sugeno observers for fault diagnosis in nonlinear systems is proposed. The advantage of the proposed AI based approach is that the design condition for the observers is relaxed in contrast with conventional approaches. Furthermore the potential use of decoupling techniques is reinforced. The design methodology is shown using a three tank system.

Fault detection and isolation based on Takagi-Sugeno modelling

One of the difficulties to detect and isolate faults in nonlinear systems via observer-based methods is the design of a residual generator. In this work a procedure to approach the fault detection and isolation problem in nonlinear systems is proposed. The result is obtained by deriving several subsystems, each subsystem containing information about specific faults, from the plant under consideration. Takagi-Sugeno modelling is used to design fuzzy observers and generate residuals. The detection and isolation task is solved by evaluating these residuals. The advantage of the proposed approach is that the design condition for the observers is relaxed. Furthermore the potential use of decoupling techniques is reinforced. The design methodology is shown using a laboratory three tank system.

A Hamiltonian approach to fault isolation in a planar vertical take-off and landing aircraft model

Abstract The problem of fault detection and isolation in a class of nonlinear systems having a Hamiltonian representation is considered. In particular, a model of a planar vertical take-off and landing aircraft with sensor and actuator faults is studied. A Hamiltonian representation is derived from an Euler-Lagrange representation of the system model considered. In this form, nonlinear decoupling is applied in order to obtain subsystems with (as much as possible) specific fault sensitivity properties. The resulting decoupled subsystem is represented as a Hamiltonian system and observer-based residual generators are designed. The results are presented through simulations to show the effectiveness of the proposed approach.

Characterization of frequency response functions for nonlinear convergent systems

The characterization of frequency response functions for convergent systems is considered in this paper. Besides a couple of approaches available in the literature, this paper is focused on the frequency response function proposed recently for a class of non-linear systems which are called convergent. Using some properties of convergent systems a characterization of a frequency response function based on Fourier series is obtained. This result expands a known result from linear to nonlinear systems and complements the existing results about frequency response functions of nonlinear systems. An example is utilized to show the proposed approach.

ACTUATOR AND COMPONENT FAULT ISOLATION IN A FLUID CATALYTIC CRACKING UNIT

Abstract This paper considers an observer-based approach for detection and isolation of actuator and component faults in a Fluid Catalytic Cracking (FCC) unit. Model based analytical redundancy is used on an augmented linearised model of the non-linear FCC unit to the isolation of faults. Some component faults are modelled and implemented in a software package to show the considered approach. The proposed design is tested using a non-linear simulation of the FCC unit model. The results show that the linear observer-based approach applied to an augmented state of the FCC to actuator and component fault detection and isolation can be used with success even if the non-linear behaviour of the FCC has some effect on the residuals.

Fault Detection and Isolation of Nonlinear Systems with Generalized Hamiltonian Representation

The problem of fault diagnosis in a class of nonlinear system is considered. Systems that can be written in the so-called Generalized Hamiltonian Representation (which is equivalent to an Euler-Lagrange representation) are studied, and a model-based observer approach for this class of systems is developed. The main advantage of the proposed approach is the facility to design the required observers, which take advantage of the system structure given by the Hamitonian representation. In order to show the proposed schema, a model of a permanent magnet synchronous machine is revised and the fault diagnosis schema presented. Simulation results confirm the effectivity of the proposed schema.