A Diagnostic Thau Observer for a Class of Unmanned Vehicles

This paper addresses the problem of sensor fault detection for a wide class of Unmanned Vehicles (UVs). First a general model for UVs, based on the dynamics of a 6 Degrees Of Freedom (6-DOF) rigid body, subject to gravity and actuation forces, is presented. This model is shown to satisfy the necessary conditions to the existence of a non-linear observer (Thau) when proper assumptions for the actuation forces are made. The observer can thus be used to generate diagnostic residuals inside a Fault Detection (FD) system. Finally, the proposed approach is customized for sensor fault detection on an unmanned quad-rotor vehicle, and simulation results show the effectiveness of the adopted solution.     

An autowave based methodology for deformable object simulation

This paper presents a new methodology for deformable object simulation by drawing an analogy between autowaves and elastic deformation. The potential energy stored in an elastic body as a result of a deformation caused by an external force is propagated among mass points by non-linear autowaves. The novelty of the methodology is that autowave techniques are established to describe the potential energy distribution of a deformation for extrapolating internal elastic forces, and non-linear material properties are modelled with non-linear autowaves other than geometric non-linearity. A haptic virtual reality system has been developed for deformation simulation with force feedback. The proposed methodology not only deals with large-range deformations, but also accommodates isotropic, anisotropic and inhomogeneous materials by simply modifying diffusion coefficients.     

基于无线传感器网络的压电能量收集技术

随着物联网的发展,多节点的传感器供电成为关键问题,由于环境中普遍存在低频振动,采用了压电悬臂梁结构,建立压电悬臂梁结构的电学模型,并进行了ANSYS的仿真,仿真得到电压76 V,约等于模型的理论值,验证了模型的正确性。进而继续研究了压电悬臂梁几何尺寸对固有频率的影响,振子越长,质量块越长,频率越低。从而收集低频振动环境中的能量,为传感器供电装置提供了设计的理论依据。     

基于内部阵列电极的电容层析成像系统

为了研究电容层析成像系统在测量高介电常数流体中的应用,设计了一套具有内部阵列电极的电容层析成像传感器,改善了传统传感器的灵敏度和非线性特性,拓宽了系统的测量范围。用蒸馏水作为连续相介质进行了数据采集和图像重建,并进一步研究了介质电导率对系统成像的影响。实验表明,该系统可以实现高介电常数介质的测量,并且可用来测量具有微弱导电能力的物体。     

Constructing NARMAX models using ARMAX models

This paper outlines how it is possible to decompose a complex non-linear modelling problem into a set of simpler linear modelling problems. Local ARMAX models valid within certain operating regimes are interpolated to construct a global NARMAX (non-linear NARMAX) model. Knowledge of the system behaviour in terms of operating regimes is the primary basis for building such models, hence it should not be considered as a pure black-box approach, but as an approach that utilizes a limited amount of a priori system knowledge. It is shown that a large class of non-linear systems can be modelled in this way, and indicated how to decompose the systems range of operation into operating regimes. Standard system identification algorithms can be used to identify the NARMAX model, and several aspects of the system identification problem are discussed and illustrated by a simulation example.     

加速度传感器安装方式的理论建模与响应分析

在传感器使用过程中,受其绝缘性能和安装方式的影响,通常会在传感器与被测对象之间安装绝缘过渡装置。而绝缘过渡装置性能的优异和结构的好坏直接影响着加速度传感器的最大响应频率。通过建立加速度传感器安装方式的理论模型,分析了影响传感器输出响应的主要因素。通过不同传感器、不同过渡装置及不同固定方式的组合,对传感器的输出响应进行了实验研究。结果表明：加速度传感器的最大响应频率受过渡装置的影响较大,过渡装置设计的好坏直接制约了传感器的频响范围。通过理论分析和实验研究,提出了提升带过渡装置传感器响应频率的方法。     

Fault detection and isolation in non-linear stochastic systems—A combined adaptive Monte Carlo filtering and likelihood ratio approach

This paper presents the development of a new method for solving fault detection and isolation (FDI) problem in general non-linear stochastic systems. In this paper, the faults are modelled as unknown changes in system parameters and adaptive Monte Carlo filtering approach is used in deriving an FDI scheme. Essentially, a set of adaptive Monte Carlo filters are designed based on the augmented system models along with a nominal Monte Carlo filter designed based on the nominal system model. The likelihood functions of the observations are then evaluated using the particles from these (adaptive) Monte Carlo filters and FDI is eventually achieved via the likelihood ratio test. The simulation results on a highly non-linear system are provided which demonstrates the effectiveness of the proposed method.     

Compensation of hysteresis in magnetic field sensors employing Fiber Bragg Grating and magneto-elastic materials

The paper proposes a novel magnetic field sensor where a technique for hysteresis compensation is employed. The sensor integrates a magnetostrictive material with a Fiber Bragg Grating (FBG) strain sensor. Because of hysteresis and non-linear phenomena taking place in such materials, the sensor’s performances may be sensibly reduced. To this aim, magneto-elastic material is accurately modelled in order to compensate hysteresis. In particular, the proposed approach allows to embed the compensation algorithm in the developed device, yielding to a more linear response of the sensor and to a reliable reconstruction of magnetic field. Results are shown and discussed.     

Simulation of Dynamic Interaction between the Railway Bogie and the Track in the Medium Frequency Range

In the present paper, the dynamicinteraction between a bogie of a modern railwaypassenger car and a track is considered with the helpof a discrete-continuous mechanical model. This modelenables us to investigate the bending-torsional-axialvibrations of the wheelsets coupled with the verticaland lateral vibrations of the track through thewheel-rail contact forces. The numerical results areobtained in the form of frequency response functionsfor the linearized bogie-track system as well as bymeans of computer simulation of forced vibrationsperformed for the non-linear system. Particularlysevere interaction between the bogie and the track iscaused by kinematic and parametric excitation from thetrack and by kinematic excitation due to wheel treadpolygonalization.     

On linear modelling of non-linear systems†

In many cases of interest, systems described by non-linear differential equations are modelled by linear equations for purposes of synthesizing feedback controllers. A theorem relating the stability properties of the linear model and the non-linear system is presented and discussed.     

航空发动机气路静电监测传感器特性

分析了发动机气路静电监测的原理,对监测系统关键器件—静电传感器的灵敏度分布和频率响应特性进行了研究,通过数值模拟和曲线拟合的方法确定了传感器的灵敏度分布函数,进而推导了传感器的频率响应函数,分析了传感器探极半径和对灵敏度分布与频率响应影响,以及颗粒运动速度对频率响应的影响。理论分析和模拟实验结果表明:静电传感器在空域和时域内均为低通滤波器,半径大的传感器灵敏度较高,空域频谱和时域频谱较宽。颗粒运动速度越快,传感器输出信号的频带越宽,但幅值相对越小。     

磁流变阻尼器内部流体动能的能量采集

为了构建自供能式磁流变阻尼器内部实时状态监测传感系统,本文介绍了一种针对磁流变阻尼器内部流体能的能量采集装置。该装置被安装于磁流变阻尼器活塞顶端并为检测阻尼器内部工作参数的无线传感模块1供电。根据能量守恒定律,推导出磁流变阻尼器中磁流变液流动能的理论模型。通过实验测试分析了在不同的外界激励下能量采集装置的工作情况,证明了采集的电能随着活塞的运动频率增加而增加,而与磁流变阻尼器的磁流变特性没有明显的关系。测试表明利用此装置能较好的采集到来自于磁流变阻尼器内部流体流动产生的能量,为无线传感模块供电。     

A remote query magnetostrictive viscosity sensor

Magnetically soft, magnetostrictive metallic glass ribbons are used as in-situ remote query viscosity sensors. When immersed in a liquid, changes in the resonant frequency of the ribbon-like sensors are shown to correlate with the square root of the liquid viscosity and density product. An elastic wave model is presented that describes the sensor response as a function of the frictional forces acting upon the sensor surface.     

Analysis and experimental verification of a forth order plant modelfor manipulator force control

The analysis and experimental verification of a fourth order model of the arm/sensor/environment system plant, to be used in evaluation of force control strategies are presented. Both the undamped and underdamped eases are investigated. Approximations and qualifications, based on the reality of our experimental system, help reduce the solution to just a few dominant terms. Comparing these terms with experimental data of the system undergoing small oscillations yields approximate values for all of the parameters in the model. To justify the obtained values and thereby the approximations used, two measures are taken. First, a simulation of the fourth order model is performed, and compared against experimental data obtained from the CMU DD Arm II system. Second, a stability analysis of several force control schemes acting on the modelled plant is reviewed and compared against experimental tests of the controllers. In both cases, the simulation and analysis match closely with the experimental results, confirming the validity of the plant model     

非线性电路分析系统的设计及仿真研究

针对MATLAB在解析高阶非线性电路时存在的困难以及与当前主流电路系统分析软件的不兼容性,设计了基于MATLAB平台并兼容SPICE规范的电路分析系统.研究的主要内容有:使用离散化伴随模型降维方法得到非线性器件的直接与递归线性化仿真模型,用四象限法进行非线性电路的直流计算,对时域线性多步数值积分方法的初值、步长和断点进行了优化设计.结果表明:系统保证了电路的仿真精度,大大加快了仿真速度,且降低了对工作平台的要求,弥补了 MATLAB平台在高阶非线性电路仿真方面的不足.     

基于薄膜体声波谐振器的柔性有机挥发性气体传感器

本文制造了一种基于薄膜压电体声波谐振器的柔性有机挥发性（VOCs）气体传感器。通过转移印刷的方法,柔性体声波谐振器的电极与压电层采用的无机材料薄膜被从硅衬底上转移到超薄的聚酰亚胺基底上。该柔性谐振器的品质因数达到了1920,且在2.5 mm的弯曲半径下仅有相对于基频十万分之一左右的频率偏移。谐振器表现出了对于环己烷与乙醇气体良好的频率响应特性,且通过在器件表面修饰聚异丁烯（PIB）薄膜作为气体吸附材料,使得器件对于环己烷的响应提升了10倍以上。该柔性VOC气体传感器具有尺寸小,质量轻,机械柔性好的优点,在可穿戴环境检测设备,健康监测设备,食品变质检测的电子标签等领域有着广泛的应用前景。     

Neural network modelling of a compliant device to enhance and simplify compliant force control

A method is offered that uses an artificial neural network (ANN) to simplify the problem of mapping a robot tool position in space when using compliant force control. For this case, the compliant device (CD) is a moulded rubber block situated between the manipulator end flange and the tool. A force sensor is mounted between the tool and the CD. It is necessary to be able to relate the recorded contact forces and torques (hereafter referred to as “forces”) to the changes in translations and orientations (hereafter referred to as “positions”) of the tool relative to the manipulator. Usually, a complex Newtonian model would be required to achieve this. For this paper, to overcome the difficulties of accurately modelling the non-linear and highly coupled characteristics of the CD, back propagating ANNs have been trained to relate the forces to positions for real data sets. The finished ANN is to be used as part of a computer model of the overall manipulator system. This paper assesses the ability of the ANN to model the CD. In particular, three issues are addressed: first, the comparison of the ANN with a conventional spring type model; second, the verification of the ANN with true data sets; third, the need to filter the ANN output to avoid problems from outliers.     

A method for parameter estimation of a class of non-linear distributed systems under noisy observations

A method is presented for estimating an unknown parameter of a distributed parameter system which depends on the system state. The system considered is modelled by a class of non-linear partial differential equations of a parabolic type. Noisy observations are assumed to be taken through an arbitrary number of sensors allocated on the spatial region. First, the explicit form of the stationary solution of the state equation is discussed. Second, use is made of the maximum likelihood approach to obtain the optimal estimate of the unknown parameter. Consistency properties w.p.1 of the optimal estimate obtained are also shown. Finally, results of digital simulation experiments are included to support the theoretical aspects.