Foreword Chapter 1 Introduction to SHM (Daniel L Balageas) Chapter 2 Vibration-based techniques for SHM (Claus-Peter Fritzen) Chapter 3 Fiber-optics sensors (Alfredo Guemes and Jose M Menendez) Chapter 4 SHM with piezoelectric sensors (Philippe Guy and Thomas Monnier) Chapter 5 SHM using electrical resistance (Michelle Salvia and Jean-Christophe Abry) Chapter 6 Low frequency electromagnetic techniques (Michel B Lemistre) Chapter 7 Capacitive methods for SHM in civil engineering (Xavier Derobert and Jean Iaquinta) Short Bibliographies of the Contributors Index

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Structural health monitoring

Fault-tolerant control based on belief rule base expert system for multiple sensors concurrent failure in liquid launch vehicle

This article investigates transmissibility operators for time-variant systems with bounded nonlinearities. Transmissibility operators are mathematical objects that characterize the relationship between two subsets of responses of an underlying system. The underlying system parameters and nonlinearities are assumed to be unknown. Time-domain transmissibility operators are independent of the system inputs and initial conditions. In this article, we propose an algorithm to identify time-varying transmissibilities using recursive least-squares and noncausal finite impulse response models. The identified transmissibilities are then used for fault detection in three different systems. The first system is an autonomous multirobotic system formulated to emulate connected autonomous vehicle platoons, where the varying parameters are the robot mass and the ground friction coefficient. The second system is a flexible structure with unknown excitation, where the variant parameter is the location of the excitation. Finally, the third system is a robotic manipulator that picks objects with different mass values. 

Transmissibility-Based Fault Detection for Robotic Applications With Time-Varying Parameters


 In this article, we investigate how to identify faulty sensors in piezoelectric actuators used for precise positioning. Four sensors are distributed along the actuator's cantilever structure to measure the deflection (displacement) at various points. We suggest identifying the sensor and detecting the fault in one of the sensors, which is thought to be faulty or producing a degraded signal. To address this, we suggest using transmissibility operators, which are mathematical estimators that estimate sensor measurements based on another set of sensor measurements within the same system. This estimation is highly robust against any external excitations/disturbances, as well as any unknown nonlinearities or unmodeled dynamics. The estimation robustness allows failure detection to be carried out even in significant actuator hysteresis nonlinearity and outside disturbance. Simulation results with various sensor fault conditions verified the suggested strategy.

Output Estimation and Failure Detection in Cantilever Bimorph Actuator using Transmissibility Operators

This paper investigates transmissibility operators for time-variant systems with bounded nonlinearities. Transmissibility operators are mathematical relations between a set of system responses to another set of responses within the same system. Both parameter variation and system nonlinearities are considered to be unknown. Transmissibility operators are shown in the literature to be independent of the system inputs. The bounded nonlinearities are considered as independent excitations on the system, which renders transmissibilities independent of these nonlinearities. To overcome the unknown parameter variation, we propose identifying transmissibilities using recursive least-squares in the form of noncausal FIR models. The recursive least squares algorithm is used to optimize what dynamics to include in the transmissibility operator, and what dynamics to exclude with the system nonlinearities. The identified transmissibilities then become robust against parameter variation and unknown nonlinearities. Next, transmissibilities are proposed for fault detection an autonomous multi-robotic system formulated to emulate connected autonomous vehicle platoons. The variant parameters are the robot mass and the ground friction coefficient. 

Transmissibility-based Fault Detection in Systems with Unknown Time-Varying Parameters

The beam-like structures commonly exist in engineering systems and there are many critical issues relevant to fault diagnosis of those structures. Noticeably, among all other existing methods, transmissibility function-based diagnostic methods, providing much more sensitive damage indexes, are frequently applied and extensively studied, and it is thus meaningful to have a thorough review on most recent advance and related technical difficulties. This paper is, therefore, to present a comprehensive review on this topic for those engineering-oriented beam-like structures, focusing on fundamental theory, critical fault properties and potential applications, respectively. According to different transmissibility function-based features, existing methods are classified into several categories, i.e. general linear transmissibility function, general nonlinear transmissibility function, generalized frequency response function and the second-order output spectrum. With a chain-type multi-degree-of-freedom model with additional connections used for analysing dynamics of beam-like engineering structures, essential topics of these methods including types of transmissibility functions, damage indexes and procedures are discussed in detail. Moreover, the effectiveness, merits and demerits are illustrated by the numerical and experimental results, respectively. It should be noted that some methods discussed here can be readily extended and applied to diagnosis of other plate-like and rotor-like, etc., engineering structures. Apart from fault detection and localization, more sensitive transmissibility function-based damage indicators providing severity and residual life of damaged structures would be further development topics in this area.

Mingfu Liao

Papers

Transmissibility function-based fault diagnosis methods for beam-like engineering structures: a review of theory and properties