寄生式时栅传感器动态测量误差的贝叶斯建模

为了提高寄生式时栅传感器的测量精度,分析了它的工作原理和动态误差组成,得到其主要误差分量为常值误差、周期误差和随机误差等。针对寄生式时栅误差特点,建立了寄生式时栅动态误差高精度预测模型,并与其他建模方法进行了比较。选用插入标准值的贝叶斯预测模型,以实际测量的传感器第一个对极动态误差数据进行建模,在后续对极特定位置插入部分实际误差测量数据,建立误差预测模型,预测了传感器后83个对极的动态误差。另选用三次样条插值和BP神经网络建模方法对寄生式时栅整圈动态误差建模,并与建立的误差模型进行了对比。验证实验表明,三次样条插值建模时间最短(0.62s),但其建模精度不高(16.050 0″);贝叶斯动态模型建模时间(0.86s)略长于三次样条插值,但建模精度最高(0.415 3″);BP神经网络建模时间最长(32min),但建模精度最低(19.680 2″)。同时贝叶斯插入标准值建模方法所需数据点(69395个)远少于三次样条和BP神经网络建模数据点(235526个),节省了大量的标定时间和建模数据量,因此可用于寄生式时栅传感器的动态测量误差高精度建模修正。     

Introducing an Evolving Local Neuro-Fuzzy Model – Application to modeling of car-following behavior

This paper proposes an Evolving Local Linear Neuro-Fuzzy Model for modeling and identification of nonlinear time-variant systems which change their nature and character over time. The proposed approach evolves through time to follow the structural changes in the time-variant dynamic systems. The evolution process is managed by a distance-based extended hierarchical binary tree algorithm, which decides whether the proposed evolving model should be adapted to the system variations or evolution is necessary. To represent an interesting but challenging example of the systems with changing dynamics, the proposed evolving model is applied to model car-following process in a traffic flow, as an online identification problem. Results of simulations demonstrate effectiveness of the proposed approach in modeling of the time-variant systems.     

一类迟滞非线性振动系统建模新方法

用理论和试验相结合的手段研究一类迟滞非线性振动系统的动力建模, 提出一种新的建模方法, 用此方法建立非线性模型用来描述这类系统的动态特性。该模型用非线性刚度和非线性阻尼机理构造, 刚度和阻尼机理由理论和试验推出, 模型中的参数由试验数据辨识。用所建模型重构恢复力——位移迟滞环, 结果表明, 该模型能很好描述这类非线性振动系统的特性, 模型中各参数的重要性得到展示, 提出的建模方法实用且有效。     

A Conceptual Approach to Integrate Design and Control for the Epoxy Dispensing Process

Performance improvement of manufacturing systems in the semiconductor industry involves interdisciplinary expertise, such as physical modeling, mechanical design, electrical control, and even material science. Integration of these different disciplines is a challenging problem in the semiconductor industry. The paper presents a conceptual approach to integrate design and control methodology for complex processes with specific application to an epoxy-dispensing control system – a critical equipment in the semiconductor packaging process. This methodology includes three hierarchical levels: process design (system-level and component-level), multivariable control and the statistics-based supervision. This paper deals with conceptual design at system-level by integrating an approximate model with an axiomatic approach, and briefly introduces approaches at other levels. In the conceptual design at system level, the primitive model of the system is sufficient to show some basic properties of the process, by which the axiomatic design can be easily integrated to evaluate the system design and suggest an optimal system configuration with invariant properties to internal variations. Under minimal internal variation, the multivariable control that is intended to suppress external variations can be approximately constructed by a set of independent controllers. Statistics-based supervision will provide suitable setpoints for the multivariable control so as to maintain good performance in the dynamic environment.     

冷轧机垂向辊系非线性振动建模与稳定性分析

考虑轧制界面的非线性阻尼和辊系-机架间的非线性刚度影响,建立冷板带轧机两自由度垂向系统非线性自激振动模型.利用奇异值理论讨论不同参数条件下系统的稳定性,并通过平均法求解垂向振动系统一次近似解,得到系统的振幅、相位微分特性方程.分析了刚度、阻尼等非线性参数变化对系统稳定性及振动特性的影响,并采用数值仿真方法验证了理论推导结果的正确性,为抑制冷轧机垂向辊系系统振动提供了一定的理论指导.     

传感器动态建模的最小二乘支持向量机方法

提出了应用最小二乘支持向量机（LSISVMs）建立传感器动态模型的方法。LS-SVMs的训练过程遵循的是结构风险最小化原则，而不是通常神经网络的经验误差最小化原则，遵循该原则可获得更好的泛化性能，且不易发生局部最优及过拟合现象，因此可以克服应用人工神经网络建立传感器动态模型的缺陷。通过实例验证了该方法的实用性及可靠性。实验结果表明，即使传感器动态模型存在严重非线性，该方法也仍然有效。     

Effects of eccentricity defect on the nonlinear dynamic behavior of the mechanism clutch-helical two stage gear

This paper investigates the nonlinear dynamic behavior of an automotive clutch coupled with a helical two stage gear system. The nonlinear dynamic model is simulated by twenty seven degrees of freedom and including three types of nonlinearity: dry friction path, double stage stiffness and spline clearance. The utility of the proposed nonlinear model is illustrated by the industrial need to clearly identify the dynamic behavior of mechanical elements (shafts, bearings, gears, flywheel, pressure plate, hub of the clutch…) and reduce vibration. The governing nonlinear time varying motion equation formulated is resolved by the analytic Runge Kutta method.Then the modeling of the eccentricity defect located on the gear and the flywheel of the clutch is done. The effect of this defect on the nonlinear dynamic behavior of the system is investigated.     

非线性液压弹簧力对电液伺服系统非线性动力学行为影响的研究

探究了非线性液压弹簧力对电液伺服系统动态特征的影响。根据非线性动力学原理,建立了系统的动力学模型。通过理论研究指出,非线性液压弹簧力作用可以用Duffing方程描述。通过数值分析揭示了系统内在的分岔现象及典型非线性动力学行为。通过对实测数据进行深入的分析,揭示了液压弹簧的软硬弹簧特性引起的“跳跃现象”。发现液压弹簧力的非线性作用会引发非线性振动,在系统建模与动态特性研究时应该将其非线性作用考虑在内。     

基于多层级数据分配的机床生命周期环境影响评价

针对机床产品的生产消耗量大和环境排放复杂,采集的数据来自于零件、车间、企业多个层级,难以直接应用于生命周期评价的问题,提出了多层级数据分配计算方法,建立了基于多层级数据分配的生命周期清单获取模型和基于产品生命周期的环境影响排放清单量化模型,建立了生命周期评价指标体系及环境影响分类,分析了机床产品生命周期的环境影响评价。结合调研数据进行机床的环境影响评价,对所提方法进行了验证说明。     

Numerical and experimental investigation on electromechanical aileron actuation system with joint clearance

A closed-loop coupling model at the system-level is developed to analyze the effects of joint clearance on the dynamic responses of electromechanical aileron actuation system. The proposed model considers the coupling effects between the electromechanical actuator (EMA) control performance and dynamic characteristics of linkage mechanism with joint clearance. Besides, the experiments are conducted in a test rig, which verifies the effectiveness of the proposed closed-loop coupling model. The nonlinear contact force model and modified Coulomb friction model are adopted in the joint clearance of the linkage mechanism, and the influences of clearance size on the dynamic behaviors of electromechanical aileron actuation system are studied. The numerical and experimental results indicate that the novel closed-loop coupling model, considering the EMA control performance and dynamics of linkage mechanism with joint clearance at the same time, is an effective model to predict the dynamic characteristics of electromechanical aileron actuation with joint clearance, which provides a practical method to analyze the dynamic performance of electromechanical coupling multibody systems with joint clearance.

     

非线性状态空间方法辨识电液伺服控制系统

针对回归神经网络辨识和建立非线性动态系统模型的问题,研究非线性状态空间描述的回归神经网络数学模型。讨论极小均方误差网络训练收敛准则,通过研究Kalman 滤波估计公式中的随机变量,提出一种参数增广的回归神经网络非线性状态方程,无导数的Kalman滤波器用于增广参数估计,人工白噪声强迫网络学习,更新网络权值,避免了扩展Kalman滤波器计算Jacobian信息和基于递度学习算法收敛慢的问题。在电液伺服系统辨识建模的应用中表明,回归神经网络较好地跟踪了液压油缸压力变化,与扩展Kalman滤波估计学习算法相比,新的算法具有较快的收敛和精度。     

基于DPCA-RBF网络的工业流化床乙烯气相聚合过程的软测量研究

工业流化床乙烯气相聚合反应是一个复杂的生产过程,具有高维、非线性、动态性和强噪声特点,质量变量难以直接测量。为解决关键质量变量在线软测量问题,首先采用动态主元分析(DPCA)的方法对过程变量提取主元,消除了过程变量之间的相关性、噪声并体现了建模数据的动态特性;其次对提取出的主元变量采用径向基函数网络(RBF)建模的方法,建立主元变量和质量变量之间的网络结构。对纯函数数据以及工业现场数据分别进行PCA-RBF模型及DPCA-RBF模型的仿真研究,研究结果表明,当建模数据存在非线性、动态性、噪声以及相关性等特性时,DPCA-RBF建模方法比PCA-RBF及单纯的RBF建模方法更优越。因此,DPCA-RBF建模方法较适合运用在工业实时变量的软测量中。     

Remaining Useful Life Model and Assessment of Mechanical Products: A Brief Review and a Note on the State Space Model Method

The remaining useful life(RUL) prediction of mechanical products has been widely studied for online system performance reliability, device remanufacturing, and product safety(safety awareness and safety improvement). These studies incorporated many di erent models, algorithms, and techniques for modeling and assessment. In this paper, methods of RUL assessment are summarized and expounded upon using two major methods: physics model based and data driven based methods. The advantages and disadvantages of each of these methods are deliberated and compared as well. Due to the intricacy of failure mechanism in system, and di culty in physics degradation observation, RUL assessment based on observations of performance variables turns into a science in evaluating the degradation. A modeling method from control systems, the state space model(SSM), as a first order hidden Markov, is presented. In the context of non-linear and non-Gaussian systems, the SSM methodology is capable of performing remaining life assessment by using Bayesian estimation(sequential Monte Carlo). Being e ective for non-linear and non-Gaussian dynamics, the methodology can perform the assessment recursively online for applications in CBM(condition based maintenance), PHM(prognostics and health management), remanufacturing, and system performance reliability. Finally, the discussion raises concerns regarding online sensing data for SSM modeling and assessment of RUL.     

基于REFOR算法的多输出非线性系统动态参数化建模方法研究

针对多输出非线性系统动态模型的辨识问题,提出一种新的非线性系统动态参数化建模方法,即冗余向前延拓正交（Redundant extended forward orthogonal regression,REFOR）算法。该算法旨在消除传统向前延拓正交（Extended forward orthogonal regression,EFOR）算法因遗漏某些重要模型项而造成所建模型精度较低的问题。首先,基于系统在各工况下辨识所得非线性有源自回归（Non-linear autoregressive with exogenous inputs,NARX）模型,利用REFOR算法统一各模型结构得到模型系数与设计参数间的函数关系,进而建立多输出非线性系统的动态参数化模型。其次,以四自由度非线性系统为例,说明了REFOR算法的优势及其在系统建模中的应用。最后,利用REFOR算法建立悬臂梁的动态参数化模型,并将REFOR预测输出与试验测得输出进行对比,试验结果表明,基于REFOR算法建立的非线性系统动态参数化模型,能准确预测系统的输出响应,为非线性系统建模方法的优化设计提供了理论基础。     

机器人柔性臂动力学建模的D-Holzer法

从改进柔性臂的模化原则出发,提出了多连杆复杂的柔性臂系统动力学建模的更为一般化的简单有效的D-Holzer法。用该法推导了两连杆柔性臂系统的动力学模型,并进行了动力学仿真。     

Identification of micro-vibro-impacts at boundary condition of a nonlinear beam

Under high amplitude vibrations, contact interfaces experience micro-vibro-impacts and frictional slips. These nonlinear mechanisms can introduce response nonlinearity and energy dissipation into the structures containing them. Beams are widely used in engineering structures and almost in every application they are subjected to boundary conditions. Boundary conditions may contain nonlinear contact interfaces. Therefore, modeling accurately the micro-vibro-impacts and frictional slips developing at the boundary condition of a beam is important in structural dynamics. Ignoring this may result in major discrepancies between experimental observations and theoretical calculations. In this paper identification of micro-vibro-impacts and frictional slips at boundary condition of a nonlinear beam is considered. The structure, being modeled as an Euler-Bernoulli beam, is analyzed using nonlinear normal modes. A reduced-order model governing the dynamic response of the beam near its first resonant point is resulted from the analysis. Identification of the nonlinear boundary condition parameters can be performed by means of the reduced order model and using experimental results.     

电子产品动态损伤最优估计与寿命预测

针对电子产品寿命预测中存在的不确定性因素影响,提出一种基于粒子滤波的电子产品动态损伤最优估计和寿命预测方法.首先建立了电子产品动态损伤HMM模型;分析了电子产品动态损伤和寿命预测中的不确定性因素;通过贝叶斯滤波模型,将寿命预测的不确定性问题转化为最优估计问题;利用粒子滤波算法求解出电子产品动态损伤的最优估计值,从而进行寿命预测;实验证明,该方法可有效消除系统和测量因素的干扰,明显提高电子产品剩余寿命预测的精度.     

Sensor fault diagnosis with a probabilistic decision process

In this paper a probabilistic approach to sensor fault diagnosis is presented. The proposed method is applicable to systems whose dynamic can be approximated with only few active states, especially in process control where we usually have a relatively slow dynamics. Unlike most existing probabilistic approaches to fault diagnosis, which are based on Bayesian Belief Networks, in this approach the probabilistic model is directly extracted from a parity equation. The relevant parity equation can be found using a model of the system or through principal component analysis of data measured from the system. In addition, a sensor detectability index is introduced that specifies the level of detectability of sensor faults in a set of analytically redundant sensors. This index depends only on the internal relationships of the variables of the system and noise level. The method is tested on a model of the Tennessee Eastman process and the result shows a fast and reliable prediction of fault in the detectable sensors.     

Bifurcation Analysis of an Electrostatically Actuated Nano-Beam Based on Modified Couple Stress Theory

In this paper, the nonlinear size-dependent static and dynamic behavior of an electrostatically actuated nano-beam is investigated. A fully clamped nano-beam is considered for the modeling of the deformable electrode of the NEMS. The governing differential equation of the motion is derived using Hamiltonian principle based on couple stress theory; a non-classical theory for considering length scale effects. The nonlinear partial differential equation of the motion is discretized to a nonlinear Duffing type ODE’s using Galerkin method. Static and dynamic pull-in instabilities obtained by both classical theory and MCST are compared. At the second stage of analysis, shooting technique is utilized to obtain the frequency response curve, and to capture the periodic solutions of the motion; the stability of the periodic solutions are gained by Floquet theory. The nonlinear dynamic behavior of the deformable electrode due to the AC harmonic accompanied with size dependency is investigated.     

融合应力集中因子与贝叶斯理论的结构健康评估方法

针对传统结构健康评估方法评估精度较低的现状,提出一种融合应力集中因子与贝叶斯理论的结构健康评估方法。首先,结合基于应力集中因子的序化模型策略与非齐次泊松过程,运用贝叶斯理论方法对试验信息及总体过程参数的序化关系进行有效融合,推导出适合不同初始损伤状态的过程参数先验分布。同时,基于应力集中递进因子与似然函数的概念,建立融合应力集中因子与贝叶斯定理非齐次泊松过程的参数后验分布预测方法。最后对提出的结构健康评估方法进行实例研究,并将预测结果与独立的试验结果进行比较。结果表明,提出方法的平均预测精度为91.99%,可以实现通过少量试验信息完成结构健康状态评估的目的,从而为结构健康的精确评估提供了一种思路。