数字指示轨道衡检定结果的不确定度评定举例

通过对数字指示轨道衡检定方法的分析,建立测量模型,评定各不确定度分量,特别是对特殊砝码——检衡车所带来的不确定度分量进行分析合成.并将评定结果分为两部分,对40t和大于80t两个称量点进行评定,最终得到相应扩展不确定度评定结果.     

Monto Carlo方法在测量不确定度评定中的应用

测量不确定度的评定决定了测量结果的可靠程度,而测量中的测量不确定度分量往往是服从各种分布的随机变量,当随机变量是非正态分布时,测量不确定度的计算公式的误差较大.本文借助于Monto Carlo(MCS)方法对测量不确定度分量进行分析处理并加以评定.仿真结果表明,该方法在测量不确定度的模型建立上具有较好的效果,且适用范围更加广泛.     

原子荧光光谱法对土壤中砷测量结果的不确定度评定

通过原子荧光光谱法对土壤中砷测量结果不确定度的评定实践,分析该方法测定过程的不确定度来源,建立数学模型并计算各标准不确定度分量、合成标准不确定度、扩展不确定度等,从而评定其不确定度。     

砝码真空质量值测量结果的不确定度评定

本文以全国砝码质量参数倍量、分量计量比对项目为实例,论述了砝码真空质量值测量结果不确定度的评定方法。对砝码真空质量值的测量方法进行概述,建立数学模型,实际测量被检砝码。对影响测量结果的不确定度来源进行分析,采用了A类评定和B类评定两种不确定度评定方法计算标准不确定度分量;给出合成标准不确定度、扩展不确定度及报告。     

工业用苯乙烯中微量苯测定的不确定度评定

本文依据JJF1059-1999测定不确定度评定与表示,对工业用苯乙烯中微量苯测定的不确定度进行了评定,分析了各不确定度分量,建立了数学模型,并计算了其测定结果的扩展不确定度。     

通用型聚苯乙烯树脂中残留苯乙烯单体的不确定度评定

本文依据JJF1059-1999测定不确定度评定与表示[1],对通用型聚苯乙烯树脂中残留苯乙烯单体测定的不确定度评定,分析了各不确定度分量,建立了数学模型,并计算其测定结果的扩展不确定度。     

电感测微仪示值误差的测量不确定度分析与评定

该文旨在规范电感测微仪测量不确定度的分析与评定工作,确保测量不确定度评定结果的准确可靠.该文运用国际通用GUM不确定度评定方法,建立测量模型,对以量块作为标准器,校准电感测微仪的示值误差,进行了测量不确定度评定,并分析其不确定度分量的各个来源.以期为广大测量人员提供不确定度分析参考依据.     

红外焦平面组件典型参数测量不确定度评定

针对国内红外焦平面产业发展现状,选取典型红外焦平面组件测试系统测试典型红外焦平面组件,对其典型参数进行不确定度评定。通过建立数学模型,分析计算影响测量不确定度的各个分量,分析不确定度的各个分量的合成方式,最后给出扩展不确定度。     

直流电压表检定装置测量不确定度分析与评定

介绍了直流电压表检定装置不确定度评定的一般方法、步骤、内容和表示方法。通过对检定装置各输入分量标准不确定度分析评定,进而合成直流电压表检定装置不确定度,通过选取有代表性的直流电压表,来验证检定装置不确定度分析评定的可靠性,评定出测量不确定度的报告,为电子、电器类仪器仪表实验室测量时,确定引起测量不确定度输入分量来源及其影响量,评定测量数据可靠性提供了一种方法。     

比色法测定面粉中磷化物的不确定度分析

利用分光光度计比色法测定面粉中磷化物,分析和评定影响面粉中磷化物含量的不确定度分量,建立数学模型,进而得到测量结果的不确定度。     

圆锥量规锥度的高精度光学干涉法测量

针对超精密数控机床对圆锥量规锥度高精度测量的需求,研究了一种将“大数”和“小数”相结合,准确测量圆锥量规锥度的方法.介绍了锥度测量系统的基本原理及组成,给出了实验测量结果,分析了测量系统的不确定度.该测量方法利用最大分度间隔误差为0.10〞的多齿分度台构成高准确度分度系统保证测量“大数”部分的准确性,采用激光偏振干涉装...     

Optimal adaptive interval type-2 fuzzy fractional-order backstepping sliding mode control method for some classes of nonlinear systems

In this research, a novel adaptive interval type-2 fuzzy fractional-order backstepping sliding mode control (AIT2FFOBSMC) method is presented for some classes of nonlinear fully-actuated and under-actuated mechanical systems with uncertainty. The AIT2FFOBSMC method exploits the advantages of backstepping and sliding mode methods to improve the performance of closed-loop control systems by lowering the tracking error and increasing robustness. To mitigate chattering and the tracking error, a fractional sliding surface is designed. In addition to the fractional sliding surface, an adaptive interval type-2 fuzzy compensator is used to estimate the uncertainty and perturbation of the nonlinear system in order to further reduce chattering caused by switching term as well as to enhance the perturbation rejection. In order to achieve an optimal performance, the multi-tracker optimization algorithm (MTOA) is used. Finally, a number of simulations and experimental tests are carried out to examine the performance of the AIT2FFOBSMC method.     

Robust stability and stabilization of fractional order linear systems with positive real uncertainty

This paper investigates the robust stability and stabilization of fractional order linear systems with positive real uncertainty. Firstly, sufficient conditions for the asymptotical stability of such uncertain fractional order systems are presented. Secondly, the existence conditions and design methods of the state feedback controller, static output feedback controller and observer-based controller for asymptotically stabilizing such uncertain fractional order systems are derived. The results are obtained in terms of linear matrix inequalities. Finally, some numerical examples are given to validate the proposed theoretical results.     

转向工况下主动悬架H_2/H_∞鲁棒控制研究

以转向工况下整车主动悬架系统为研究对象,用线性分式变换理论对悬架参数进行不确定性分析,应用频率加权函数对不确定性系统进行频率加权增广描述,采用H2/H∞鲁棒控制方法,对系统进行仿真分析。仿真结果表明H/H鲁棒控制可以较好地提高悬架系统综合性能。     

Robust fractional order sliding mode control of doubly-fed induction generator (DFIG)-based wind turbines

Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme.     

Optimal interval type-2 fuzzy fractional order super twisting algorithm: A second order sliding mode controller for fully-actuated and under-actuated nonlinear systems

In this paper, a novel interval type-2 fuzzy fractional order super twisting algorithm (IT2FFOSTA) which is essentially a second order sliding mode controller is presented. The proposed IT2FFOSTA enhances fractional order super twisting algorithm (FOSTA) by taking advantage of an interval type-2 fuzzy fractional order sliding surface (IT2FFOSS) for some classes of fully-actuated and under-actuated nonlinear systems in presence of uncertainty. The FOSTA significantly reduces the amount of chattering and the IT2FFOSS results in decreasing the tracking error, control effort, and chattering level. In order to control under-actuated systems, a hierarchical sliding surface is employed. The multi-tracker optimization algorithm is utilized to adjust the controller’s parameters; this leads to an optimal performance for the IT2FFOSTA. To examine the performance of the IT2FFOSTA, some simulation and experimental tests on three examples of different classes of fully-actuated and under-actuated systems, including ball and plate, inverted pendulum, and ball and beam systems are carried out. The simulation and experimental results demonstrate the superiority of the IT2FFOSTA in reducing the amount of chattering, tracking error, and control effort compared to those of the other control methods.     

Probabilistic robust stabilization of fractional order systems with interval uncertainty

This study investigates effects of fractional order perturbation on the robust stability of linear time invariant systems with interval uncertainty. For this propose, a probabilistic stability analysis method based on characteristic root region accommodation in the first Riemann sheet is developed for interval systems. Stability probability distribution is calculated with respect to value of fractional order. Thus, we can figure out the fractional order interval, which makes the system robust stable. Moreover, the dependence of robust stability on the fractional order perturbation is analyzed by calculating the order sensitivity of characteristic polynomials. This probabilistic approach is also used to develop a robust stabilization algorithm based on parametric perturbation strategy. We present numerical examples demonstrating utilization of stability probability distribution in robust stabilization problems of interval uncertain systems.     

顶空-气质联用法测定卷烟包装材料中苯不确定度评定

采用顶空-气相色谱/质谱联用法分析卷烟包装材料中苯的残留不确定度,通过建立数学模型,分析不确定度的主要来源,计算各个不确定度分量,将不确定度合成,得到该分析方法的测量不确定度评定方法。结果表明,样品测定过程中总的重复性引起的测量不确定度所占权重最大,其次是拟合标准工作曲线所引入的不确定度,配制标液过程中引入的测量不确定度所占权重最小。通过统计分析发现,回收率与100%差异不显著,当苯残留含量为0.010 mg•m^-2时,该分析方法的测量扩展不确定度为0.001 mg•m^-2（k=2)。     

Robust stability analysis of fractional order interval polynomials

The paper deals with the robust stability analysis of a Fractional Order Interval Polynomial (FOIP) family. Some new results are presented for testing the Bounded Input Bounded Output (BIBO) stability of dynamical control systems whose characteristic polynomials are fractional order polynomials with interval uncertainty structure. It is shown that the Kharitonov theorem is not applicable for this type of polynomial. A procedure is given for computation of the value set of FOIP. Based on the value set, an algorithm is presented for testing the stability of FOIP. The results presented in the paper are useful for the analysis and design of Fractional Order Interval Control Systems (FOICS). Examples are given to show how the proposed method can be used to assess the effects of parametric variations on the stability in feedback loops with fractional order interval transfer functions.     

电液比例系统的H_∞鲁棒性控制设计

针对电液比例系统中系统控制数学模型参数时变要求控制器鲁棒性强的特点,通过分析电液比例系统的物理模型,利用线性分式变换(LFT)方法,引入乘性不确定性参数,给出了参数时变的电液比例模型,并得出了具有参数不确定性系统状态空间函数模型。运用线性矩阵不等式(LM I)的H∞控制器的处理方法,设计出基于H∞控制的电液比例系统控制器。利用该控制器可有效的抑制参数时变对系统输出的影响。仿真表明该控制器在较大不确定参数的变动下,控制器仍然能够使系统具有较好的输出性能,结果说明该鲁棒控制器的有效性。