基于三维实体模型的多坐标数控加工过程仿真

概述了目前数控加工程序仿真系统的各种设计方法,分析了在三维实体模型中多坐标数控加工过程仿真研究的关键技术,并提出了实现方法。通过实际仿真系统的开发和系统运行表明,提出的方法简洁有效,系统运行可靠。     

空间对接半物理仿真系统失真的内模控制方法

在空间对接半物理仿真系统中,运动模拟器的响应延迟会导致系统产生发散失真现象,甚至导致机械部件损伤。为解决该系统失真问题,提出了基于内模控制的系统失真补偿方法。本文分析了系统的失真原理,将内模控制方法应用于该系统,并等效为内模PID控制(IMC-PID)模型。利用模型辨识方法,采用二阶模型拟合高阶模型。对于空间对接半物理仿真系统,进行单自由度碰撞数字仿真与实验,验证该方法的可行性,为空间对接半物理仿真系统的失真问题提供了新的解决方法。     

液压系统故障树分析技术的研究现状与发展趋势

介绍了近年来国内外液压系统故障树分析(FTA)的研究现状,着重总结了基于模糊数和基于T-S模型的液压系统模糊FTA方法,评述了二态系统、多态系统重要度和模糊重要度等重要度分析方法,归纳了基于FTA的故障诊断专家系统和故障搜索方案等故障诊断优化方法,指出借鉴其他系统的FTA方法并移植到液压系统中、将现有的FTA方法与其他算法相融合是液压系统FTA领域今后的发展趋势。     

基于高阶高增益滑模观测器的混沌同步研究

基于驱动响应结构,针对一类混沌系统,提出了一种高阶高增益响应系统的设计方法。基于增维的思想,所提出的响应系统不仅能估计出系统的状态,还能估计出状态的微分。基于混沌同步,考虑了该类混沌系统的基于混沌同步的保密机制,在发射器和接受器达到同步的前提下,提出了一种新的信号还原的方法。该方法没有用到系统的微分信息,同时对强时变信号可以还原。针对一个SQCF混沌系统进行仿真实验,结果表明了方法的有效性。     

基于反共振原理的双频载荷作用下轴承保护环的设计

在传统转子-轴承系统的设计基础上,根据反共振原理提出采用弹性支承元件和考虑轴承弹性的方法来设计轴承系统,研究了双频载荷作用下轴承系统的设计方法。此方法考虑了整个系统的动态特性,并将在此方法下求得的轴承振幅与没有施加保护环之前求得的轴承振幅进行了比较。     

国产控制系统及仪表在大型有机硅装置上的应用

介绍了国产DCS集散控制系统及仪表在新安股份大型有机硅装置的应用情况,叙述了DCS系统的特点、组成结构和系统硬件配置方案,并介绍了系统组态流程和主要控制方案的实现方法,其中重点描述了精馏塔塔釜液槽液位均匀调节系统和精馏塔压力分程调节系统等复杂调节系统的控制方法和组态框图,介绍了算法组态方法及利用结构化文本语言来实现硅粉累积计量等特殊算法的程序方法,介绍了系统主要配套热工检测仪器仪表的选型情况和应用结果总结。     

论虚拟生产系统的制造资源组织模式及其系统构建算法

针对敏捷制造环境提出了基于虚拟生产系统的制造资源组织模式。探讨了基于虚拟生产系统的资源组织模式的理论思想,说明了虚拟生产系统对制造资源的处理方法,给出了基于虚拟生产系统的制造资源组织架构;分析了构建虚拟生产系统的一般方法和资源确定原则,并着重阐述基于产品和车间信息的虚拟生产系统的构建算法。作为案例研究,讨论了运用虚拟生产系统方法在半导体封装制造系统中进行生产组织的应用过程。     

雷达装备虚拟维修性设计及评价方法研究

针对雷达结构传统维修性评价方法中存在的时间滞后、成本高、主观差异性和缺乏系统有效的定量方法等问题,构建了一个雷达虚拟维修性设计与评价系统,介绍了系统中基于维修度的雷达结构维修性综合评价方法,进而提出了维修性综合评价方法,同时还给出了虚拟维修集成模型构建、高效率虚拟操作技术等部分关键技术的解决方案。最后将原型系统用于某型雷达结构虚拟维修性设计与评价,验证了该系统的有效性。     

采用反馈机制的多生产线制造系统协同优化

为研究具有可互替耦合设备的多生产制造系统的优化问题,给出了该类型制造系统的一般性描述,并基于经典的MiniFAB模型设计了该多生产线制造系统。为解决优化过程中训练数据不足的问题,提出了基于反馈机制的多生产线制造系统结构优化方法。为进一步提高优化方法的精度,将结构优化方法与启发式调度规则优化结合,提出了多生产线制造系统协同优化方法。案例验证了所提出方法的可行性和有效性。     

全系统动态误差建模理论分析与应用

对测量系统进行动态特性和精度理论研究必须建立测量系统的数学模型。针对传统建模方法的缺陷,研究分析了全系统动态误差建模理论与方法,该建模理论与方法充分考虑了系统内部各组成环节的信息,建立的模型能够反映实际测量系统内部各结构单元的传递特性随时间变化对系统测量精度的影响。该建模理论与方法具有普遍的适用意义,不管是动态测量系统还是静态测量系统,用该建模理论与方法都能够建立其全误差模型。最后利用全系统动态误差建模理论与方法建立了测微系统（百分表）的全误差模型,并进行了实验验证。     

基于子结构模型剪切型框架结构损伤识别

提出了适用于剪切型框架结构的损伤定位和损伤定量识别方法。首先,用剪切型框架结构的运动方程和中心差分法确定子结构的划分方式;然后,根据子结构的输入输出关系和已知输入自回归移动平均(autoregressive moving-average with exogenous inputs,简称ARMAX)模型的对应关系,提出了利用子结构输入输出数据建立ARMAX模型的定阶方法;最后,利用子结构ARMAX模型系数向量的马氏距离来构造损伤识别指标,并选用受试者工作特征曲线下面积和Bhattacharyya距离进行损伤部位和损伤程度的识别。模拟算例和试验表明,提出方法能准确识别剪切型框架结构的损伤部位和损伤程度的相对大小,且具有较好的抗噪性能。     

ARMAX modal parameter identification in the presence of unmeasured excitation—I: Theoretical background

This study investigates the performance of a time-domain parameter estimation algorithm aimed at identifying modal parameters from excitation and response data corrupted with significant measurement noise and unmeasured sources of periodic and random excitation. The parameters of an autoregressive moving average with exogenous excitation (ARMAX) model are estimated using an iterative multistage estimation algorithm. The use of backwards autoregressive with exogenous excitation (ARX) models in the multistage algorithm allows vibrational modes to be distinguished from spurious numerical poles and is also the basis of a model selection criterion. A diagonal parameterisation of the autoregressive (AR) polynomial matrices allows the MIMO ARMAX model to be separated into a number of MISO systems, and permits simple manipulation and stabilisation of the estimated model. Measurement noise and sources of unmeasured random and periodic excitations are accounted for by the ARMAX model structure. In this paper, the theory and algorithm of the ARMAX model is given.     

Embedded estimator in predictive feedback control

In this work, a new approach to design predictive feedback control for SISO systems is presented. The proposed formulation relies on the development of a single step predictor based on an autoregressive moving average with external input (ARMAX) model. Although no explicit observer is actually involved in the implementation, this predictor implicitly includes one since the input-output model subsumes an observer. Exploiting this idea the resulting ARMAX model is extended to include extra outputs to improve the quality of the prediction for systems with large time delay and nonmeasurable disturbances. The resulting predictor is used to develop a predictive feedback controller. This new formulation of predictive feedback control includes feedback and feedforward actions. Simulations of two linear systems illustrate the applicability of the control algorithm.     

液压位置系统及其噪声模型的辨识

本文讨论了用ARNAX时间序列模型来辨识液压系统的阶和参数,同时得到系统的干扰噪声模型。文中提出的增广最小二乘法和BIC定阶准则的结合,比已有方法辨识参数和阶的精度要高。进一步根据估计参数的渐近正态性确定模型的子阶和时滞。文中应用该方法辨识了液压位置系统及其噪声模型的阶和参数。仿真和实测阶跃响应比较,证明得到的辨识模型是有效的。     

Vector ARMAX modeling approach in multi-input modal analysis

This paper analyses multivariate time series using a parametric approach for the purpose of identification of modal parameters of mechanical structures. Because of computer capacity the multi-input/multi-output (MIMO) data were treated with the multi-input/single-output (MISO) consecutively. By noting that some of the modal parameters must have global characteristics regardless of measurement locations in theory, a MIMO modeling approach is taken to analyse a set of multiple-random excitation/multiple response measurements. The MISO approach is also applied to the same data and the results obtained by the two methods are compared. Two specific regression models for the MIMO and MISO approach are derived from the vector Autoregressive Moving Average model with exogenous variables (ARMAX) and the least squares method is applied iteratively for the parameter estimation. The modal parameters are derived from the parameters of the vector ARMAX based upon the principle of impulse response invariance. The procedures are used to analyse a set of simulation data of a three degree of freedom system.     

基于预测误差法的加速度传感器动态模型参数辨识

加速度传感器动态模型对研究与分析加速度传感器的动态特性与动态误差补偿具有重要作用。针对加速度传感器动态模型的参数辨识,提出了一种基于预测误差法的加速度传感器动态模型参数辨识方法,该方法将加速度传感器的状态空间模型转化为线性带外生输入的自回归滑动平均(ARMAX)模型,获得其最优一步预测输出的表达式,并通过求解加速度传感器最优一步预测输出极小化误差准则函数,实现加速度传感器动态模型参数的最优辨识。实验结果表明,该方法有效地实现了加速度传感器动态模型的参数辨识,所得加速度传感器动态模型具有较高的精度,能描述加速度传感器的动态特性。     

Identification of multivariable nonlinear systems in the presence of colored noises using iterative hierarchical least squares algorithm

This paper presents an efficient method for identification of nonlinear Multi-Input Multi-Output (MIMO) systems in the presence of colored noises. The method studies the multivariable nonlinear Hammerstein and Wiener models, in which, the nonlinear memory-less block is approximated based on arbitrary vector-based basis functions. The linear time-invariant (LTI) block is modeled by an autoregressive moving average with exogenous (ARMAX) model which can effectively describe the moving average noises as well as the autoregressive and the exogenous dynamics. According to the multivariable nature of the system, a pseudo-linear-in-the-parameter model is obtained which includes two different kinds of unknown parameters, a vector and a matrix. Therefore, the standard least squares algorithm cannot be applied directly. To overcome this problem, a Hierarchical Least Squares Iterative (HLSI) algorithm is used to simultaneously estimate the vector and the matrix of unknown parameters as well as the noises. The efficiency of the proposed identification approaches are investigated through three nonlinear MIMO case studies.     

气压伺服系统高性能鲁棒控制器的设计

2自由度控制器越来越在伺服控制中显示其优越性。2自由度控制利用反馈控制来保证稳定性,利用前馈保证轨迹跟踪性能。首先辨识得到了气压系统的闭环传递函数。基于闭环系统辨识模型设计了零相位误差前馈控制器(ZPETC),ZPETC将闭环系统带宽拓宽为100 rad/s左右。系统的干扰抑制能力、鲁棒稳定性由控制器中反馈环节保证。设计了基于干扰观测器的内环反馈控制;外环反馈仍为位置反馈环节。与PID控制比较,整个控制器在试验中得到了良好的轨迹跟踪精度。     

COMPLEX TIME SERIES ANALYSIS FOR ROTOR DYNAMICS IDENTIFICATION: APPLICATIONS

An effective fitting strategy in the directional ARMAX model-based approach is proposed for the rotor dynamics identification. The strategy is based on a priori knowledge of the degree of anisotrophy in rotor systems gained from directional frequency response estimates. In addition, the anisotropy contribution factor is introduced in an effort to quantify the degree of system anisotropy. Finally, the applicability and effectiveness of the proposed strategy are investigated experimentally.     

ARMAX modal parameter identification in the presence of unmeasured excitation—II: Numerical and experimental verification

The performance of an autoregressive moving average with exogenous excitation (ARMAX) time-domain parameter estimation algorithm is assessed using data simulating the response of a two degree-of-freedom system and also experimental data obtained from a cantilever aluminium beam. The algorithm is aimed at identifying modal parameters in the presence of significant measurement noise and unmeasured sources of periodic and random excitation. The simulated system exhibits lightly damped modes and is excited with measured random excitation as well as unmeasured random and periodic excitation. A second case is considered where the modal frequencies of the simulated system are separated by 0.345 Hz and the frequency of an unmeasured periodic excitation is 0.257 Hz below the first modal frequency. Electrodynamic shakers as well as piezoceramic plates are used to apply multiple independent excitation forces, including measured random noise and also unmeasured random and periodic signals. Successful identification of modal parameters is achieved in the presence of up to 10% random measurement noise, as well as over 200% unmeasured periodic and random excitations. Results showed that the ARMAX algorithm achieved better results than ARX models estimated from experimental data corrupted by the effects of unmeasured excitations. The use of piezoceramic plates for structural excitation was demonstrated in experiments and the ability to excite modes was observed to be dependent on the deflection of a particular mode in the contact area of the piezoceramic plates.