Traditional MEMS filters use a comb drive structure that suffers from the pull-in instability, which places a significant limitation on the achievable signal-to-noise ratio of the sensor. Because the output signal from a capacitive sensor is linearly related to the applied voltage, it is desirable to use a capacitive sensor that can withstand large voltages upwards of 100 V. However, the pull-in instability

Estimation of the sideslip angle is significant for vehicle safety control systems such as electronic stability control. This paper proposes a vehicle-kinematic-model-based sideslip angle estimation method by fusing the information from an inertial measurement unit (IMU) and global navigation satellite system (GNSS) with aligning the heading from the GNSS. To estimate the velocity and attitude errors

Spectral analysis and system identification techniques require suitably long data sets. Linear time-invariant (LTI) systems under random input can be demanding in terms of accurate simulation of all dynamics because of calculation time. This paper details an extension of the state-space formulation of LTI systems for higher order holds, for periodic and for exponential inputs. Exact solutions of the

An approach is presented for modelling the noise propagation beneath the train floor and this is applied to rolling noise sources. It is assumed that the sound incident on the train floor is made up of a direct and a reverberant component. A combination of two numerical modelling approaches is considered to deal with these: an equivalent source model, to represent the direct component, and statistical

This paper proposes a comb-like beam (CombBeam) based piezoelectric energy harvester (PEH) for harvesting wind energy by exploiting the galloping mechanism. The CombBeam-based PEH consists of a series of parasitic beams being mounted to a conventional cantilever beam with a piezoelectric transducer. A theoretical modelling method is established to simplify the proposed CombBeam-based PEH as a mult

Identifying the local nonlinear hysteretic behaviors in structures arises as an important issue in structural health monitoring. This paper develops a new hysteresis identification framework where rather than identifying the hysteretic parameters, the restoring forces are reconstructed so as to identify the hysteretic loops. Under this new framework, there is no need to get a priori knowledge on the

This paper deals with the modelling and analysis of six degree of freedom random vibration test. It involves an advanced multi-input multi-output random vibration test system where three translational and three rotational motions can be controlled simultaneously. In this work, a mechanical model of the six degree of freedom vibration test system is established such that eight exciters are modelled

The structural damage identification based on the dynamic condensation of finite element (FE) model can effectively deal with the mismatching between the measured degree of freedom (DOF) and the total DOFs of the entire FE model, and avoid the issues of mode pairing and repeated solution of the generalized eigenvalue problem of large-scale FE models. The proper configuration of master DOFs is essential

Nowadays, coatings have been widely deposited on cutting tool inserts due to their superior wear resistant and thermal barrier effect in metal manufacturing industry. Tool coatings avoid the direct contact between the workpiece and tool substrate, thus affecting the cutting temperature and machining performance compared with uncoated tools. This article aims to review the tool coating effects on cutting

Historical failure instances of a system with diversified degradation patterns will pose great challenge for prognostics. Consequently, it is challenging to accurately predict the remaining useful life (RUL) using a prognostic model trained from such data. To solve this problem, this paper proposes a just-in-time learning-based data-driven prognostic method for reciprocating compressors with diverse

The combination of frequency based substructuring (FBS) and blocked force Transfer Path Analysis (TPA) allows to perform parametric NVH design optimizations. Blocked forces are not dependent on one specific receiver structure, in contrast to interface forces of classical TPA. Blocked forces can therefore be used as a source description in design optimization. For optimizing the assembly, different

Tuned-Mass-Dampers (TMD) have been widely used to suppress undesirable structural vibrations within a user-defined frequency band. Nevertheless, the performance of TMDs designs is quite sensitive to slight deviations in model parameters such as the ratio between the TMDs natural frequency and the frequency of the main structure. This paper proposes (i) a systematic approach to design a set of spatially

Degradation trend estimation (DTE) of rotating machinery plays a vital role in prognostics and health management (PHM). It enables us to foresee future conditions and avoid unexpected risks. Recently, considerable accomplishments in the field of rotating machinery PHM has achieved through regression analysis based data-driven prognostics, which assist in directly analyzing and exploring the relationships

In this paper, Interconnection and Damping Assignment Passivity Based Control (IDA-PBC) notion is utilized to design a novel controller for teleoperation systems with asymmetric variable time delay in the communication channel and passive/non-passive interaction forces. By shaping both of the kinetic and potential energies, the performance of position and force tracking is improved compared to conventional

The paper concerns coupling between longitudinal and transverse vibrations of tensioned Euler-Bernoulli beams with general linear boundary conditions of arbitrary elastic stiffness. The beams are assumed to be perfectly straight with symmetric boundary conditions, and excitation aligned with the longitudinal axis. Two types of excitation, harmonic and impact, are considered. A relatively simple approach

This paper presents a state-disturbance (S-D) observer-based adaptive fuzzy sliding mode control (AFSMC) to control the ball and beam system (BBS) in the presence of matched and mismatched uncertainties. First, an SMC scheme is designed to an error-based state-space representation of the BBS involving uncertainties. Stability analysis shows that the closed-loop system with the proposed SMC in the presence

In this paper, the time-variant uncertainty propagation analysis is defined to solve the output stochastic process of a time-variant function with uncertainty. And a time-variant uncertainty propagation analysis method is constructed with the combination of an extended orthogonal series expansion method (extended OSE) and sparse grid numerical integration (SGNI). The SGNI serving as a classical uncertainty

In this paper, an adaptive visual tracking controller is proposed for the nonholonomic mobile robot with an onboard monocular camera, wherein both the velocity and acceleration saturation constraints can be guaranteed by properly selecting the control parameters during the visual servoing process. Specifically, the virtual velocity-level controller is firstly designed based on the first-order filter

This paper proposes a novel hybrid piezo-dielectric (PD) wind energy harvester, to efficiently harvest the vortex-induced vibration (VIV) energy from low-speed wind. The hybrid PD harvester brings together the following two electromechanical transduction mechanisms: piezoelectric ceramic (PZT) sheets and a vibro-impact (VI) dielectric elastomer generator (DEG). The PZT sheets directly transduce the

While wrist-worn electronics have great potential in a variety of areas, their applications are currently constrained by the limited working time of their electrochemical batteries. Harvesting energy from arm swinging motions provides a promising means to address this issue. In this work, we introduce a tiny repulsive magnetic spring to improve the performance of a wrist-worn inertial energy harvester

The methods for experimental modal analysis are consolidated, as are the sensors used to perform this analysis. The characteristics of the most commonly used sensors are to be “discrete” and “independent”, that is, each sensor can measure the magnitude of interest in a single point and can be placed independently from the others on the structure. This kind of layout is widely used, for example, with

An exact dynamic stiffness method is proposed for the free vibration analysis of multi-body systems consisting of flexible beams and rigid bodies. The theory is sufficiently general in that the rigid bodies can be of any shape or size, but importantly, the theory permits connections of the rigid bodies to any number beams at any arbitrary points and oriented at any arbitrary angles. For beam members

Acoustic black holes (ABHs) in beams and plates have been extensively studied as a passive method for vibration attenuation and noise reduction. However, most research to date has focused on analyzing the behavior of a single ABH structural element, using numerical or semi-analytical deterministic approaches. If ABHs are to be exploited for practical industrial applications, there is a need to characterize

A robust steering torque control strategy for lateral tracking functionality of autonomous driving vehicles that perform active steering, active accelerating and active braking is researched in this paper. The main target of this research is to track references of lateral position and heading angle, which are provided by upstream motion planning module, via torque that robotic arm applies to steering

Guided wavefields in composite structures carry a wealth of information about wavefield anomalies from damage–wave interactions. Although such anomalies can be used for damage detection, they are easily masked by incident waves from actuators and reflected waves from structural boundaries. This research presents a concept of guided wavefield curvature for the detection of structural damage. Wavefield

The microstructural features of heterogeneous and porous materials give rise to unique non-linear dynamic behaviour. The purpose of this work is to investigate the dynamic response of thermally damaged concrete specimens measured by two different techniques: Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) and new Flipped Accumulative Non-linear Single Impact Acoustic Spectroscopy (FANSIRAS)

Scanning laser Doppler vibrometer (SLDV) measurements are affected by sensor head vibrations as if they are vibrations of the target surface itself. This paper presents practical correction schemes to solve this important problem. The study begins with a theoretical analysis, for arbitrary vibration and any scanning configuration, which shows that the only measurement required is of the vibration velocity

Robust and precise motion tracking for micro-electro-mechanical systems in the presence of inherent nonlinearity and external disturbance is of great importance in many applications. Due to high sensitivity to environmental variations, the entire model or some parameters of the system tend to change unexpectedly. Existing offline nonlinearity models are computationally intensive and may be not suitable

The non-destructive quantification of the mechanical properties of solid materials is a growing research topic for many applications. It could be used for monitoring material performance during the whole lifecycle of a component, for when sampling is limited or impossible or for applications that require sample identification. In this paper a portable instrument for non-destructive viscoelastic characterization

Gear transmission systems are widely used in mechanical equipment. Due to manufacturing and processing errors, material defects, wear and external environments, there are uncertain parameters such as mass, mesh stiffness and support stiffness. Parametric uncertainty plays an important role in response predictions of the gear transmission systems. In order to evaluate reasonably the dynamic characteristics

It is a challenge problem to accurately recognize damage distribution pattern for multi-stage industrial gearboxes in filed, due to entangled relationships between strong interferences/noises and complicate transfer path modulations. In this work, a tailored two-stage strategy (LR-CSL) based on low-rank representation and convolutional sparse learning is proposed. Based on the periodic similarity of

Fatigue pitting and abrasive wear are the most common wear mechanisms in lubricated gears, and they have different effects on the gear transmission system. To develop effective methods for online gear wear monitoring, in this paper, a vibration-based wear mechanism identification procedure is proposed, and then the wear evolution is tracked using an indicator of vibration cyclostationarity (CS). More

Rolling bearings are widely used in rotating machinery and its dynamic performance plays a significant effect on the stability, reliability and even safety of the machine. Presence of the skidding is likely to cause damages to the surfaces of the inner race, the outer race, the rolling elements, and/or the cage. In this paper, a skidding dynamics model of a rolling bearing is established to reveal

This paper introduces a novel approach to crack detection and localization in a pipeline transporting fluid under high pressure. From acoustic emission signals acquired by two R15i-AST sensors at two ends of a fluid pipeline, the proposed method scans peaks in the individual signal channels in the time-frequency domain and filters out noise to obtain acoustic emission events. Subsequently, adjacent

The spectral representation method (SRM) has been widely used to simulate stationary or non-stationary wind fields for engineering structures. Although several attempts have been made to realize the invoking of Fast Fourier Transform (FFT), the SRM is still very inefficient to simulate the fully non-stationary wind field with a time-varying coherence due to the extremely time-consuming Cholesky decompositions

Blade Tip Timing (BTT) is a non-intrusive measurement technique that can be used to estimate the vibration characteristics of rotor blades during turbomachine operation. BTT uses proximity probes mounted into the turbomachine casing to measure the Time-of-Arrival (ToA) of rotor blades at these proximity probes. The ToAs are determined using a triggering criterion on the proximity probe signal. Rotor

A component-less, long-driving-region and self-positioning piezoelectric actuator was developed to transmit several gram-weight components. The linear piezoelectric actuator was composed of a piezoelectric slab and comb-shaped capacitive position sensor. The length-to-width ratio of the driving pad was designed to ensure successive in-phase connection when the driving pad was subjected to an electric

This paper presents a theoretical and numerical analysis of one-side oscillation in a single magnetic pendulum. The system is composed of a physical pendulum with a neodymium magnet fixed to the end of the rod. The pendulum is driven by a pulsating, repulsive magnetic field generated by an electric coil placed underneath. The pendulum pivot is damped by an elastic element. The excitation current signal

Mechanical loads together with changing temperature conditions can be found in a wide variety of fields. Their effects on elastic media are reflected in the theory of thermoelasticity. For typical materials in engineering, very often a simplification of this coupled theory can be used, the so-called uncoupled quasistatic thermoelasticity. Therein, the effects of the deformations onto the temperature

High performance control requires high loop gain and large control bandwidth. However, the spurious resonances at the higher frequencies can limit the performance of such type of systems. This drawback can be overcome by using sensor fusion technique. In sensor fusion, two or more sensors are combined in synergy such that good performance is achieved at lower frequencies while ensuring robustness of

The numerical simulation of beams and plates with embedded acoustic black holes (ABHs) is computationally demanding because of the very thin thickness attained at the ABH central area. Semi-analytical approaches relying on the Rayleigh-Ritz method with wavelet or Gaussian basis functions have thus revealed as an accurate and fast alternative to determine the ABH vibration field in parametric studies

In this paper, the proper orthogonal decomposition (POD) method is first time apply to the dimension reduction of dual rotor-bearing experiment rig which is similar to an aero-engine rotor. The basic theory of the POD method and the application in dynamical system are introduced. The supporting bearing nonlinearity and the coupling misalignment of high and low pressure rotors are considered, and the

This paper presents a general framework for estimating the state and unknown inputs at the level of a system subdomain using a limited number of output measurements, enabling thus the component-based vibration monitoring or control and providing a novel approach to model updating and hybrid testing applications. Under the premise that the system subdomain dynamics are driven by the unknown (i) externally

Monitoring and control of tension in bolted joints is a difficult task that has received long-time attention. A newly proposed technique is to hammer-impact the bolts and estimate the tension based on the vibration response. This present work conducts a thorough experimental investigation of two different bolted structures to identify the potentials of the technique, particularly examining damping

In recent years, deep learning techniques have been proved a promising tool for bearing fault diagnosis. However, to extract deep features with better representative ability, how to introduce discriminant information about different fault types into the deep learning model is still challenging. Moreover, as deep learning techniques heavily rely on mass of measuring data, relatively small amounts of

Off-road motorcycles transit over significantly irregular terrains facilitated by their suspension system. The optimisation of their suspension is an open topic. On one hand, on-road motorcycles need to be extended to consider off-road peculiarities such as larger amplitude of motion and a standing rider, to provide optimisation predictions. On the other hand, an objective methodology to verify the

Vibration analysis is an effective approach to condition monitoring of hydrodynamic journal bearings. However, the analysis is largely based on the understanding of asperity-asperity interactions due to severe wears in the late phase of bearing lifetime. It often provides very tight leading time for maintenance actions. Aiming at developing effective techniques for early wear monitoring, this paper

This study is concerned with time domain fatigue analysis of offshore structures subjected to random waves. The fatigue damage calculated from a single realization of the stress time history is random, thus the mean damage is typically estimated via Monte Carlo simulation (MCS), by averaging over multiple realizations. This approach is time-consuming, because each realization involves a time domain

The solution of a case study problem of suspended payload sway damping by moving a pivot base in vertical direction is presented. Unlike for the classical problem of anti-sway control for moving the base in the horizontal direction, implemented e.g. in cranes, a direct solution by using control feedback theory for linear systems is not possible. Once the model is linearized, it becomes uncontrollable

A theoretical model is presented for the prediction of sound radiated from a semi-infinite unbaffled long enclosure with the ground. This geometrical arrangement forms an idealized representation of traffic tunnels and railway stations where noise propagates inside the long enclosures and radiates to the outside through the openings. Despite the fact that the model described here applies only to idealized

Piezoelectric bending actuators are widely used in micro positioning tasks. Due to material nonlinearities such as hysteresis and creep, the position-force control of these actuators is necessary. However, position sensors for micro scale applications are expensive and require a complex configuration. Sensorless approaches are alternative methods in which by resorting to the linear charge-position

Structural health monitoring (SHM) is backwards analysis of past to current state of damage, but cannot create a structure-specific nonlinear model for forward analysis of future response and damage. This paper aims to develop an automated modelling approach to translate proven hysteresis loop analysis (HLA) SHM results into nonlinear foundation models for response forecasting in subsequent events

The response analysis of the composite structural-acoustic systems with multiple types of epistemic uncertainties is investigated in this paper. Based on the available information for the uncertain parameters, the multiple types of epistemic uncertainties refer to probability-box (p-box) variables, evidence variables and interval variables. The proposed development focused on an efficient computation

Rigid-flexible satellites are aerospace systems with flexible parts attached to their structures, such as antennas or solar panels. Attitude Control Systems (ACS) of satellites are responsible for spatial orientation concerning a fixed reference for executing maneuvers. As a result, ACS can lead to problems in flexible structures, especially in large-scale movements, as undesired vibrations may be

The design of sensor placement in water supply pipe networks for the purpose of transient-based leakage localization is investigated. Each sensor is placed at where the Fisher information of measurement concerning leaks is maximized; equivalently, the Cramér–Rao lower bound (CRLB) representing the lower limit of leak localization error is minimized. An explicit algorithm for computing the CRLB with

An event-triggered H∞ controller is designed for an active seat suspension in this paper, where the continuous event-trigger scheme is applied to transfer the dynamic system states to the controller only at event-triggered time instants. Delay-dependent stability criteria in the form of linear matrix inequality (LMI) are presented to guarantee the asymptotic stability of the seat suspension system