基于自适应逆控制的有源滤波器的检测算法

提出一种新的并联型电力有源滤波器的检测方法,通过控制有源滤波器直流电容电压来确定电网电流所需的基波有功分量的幅值,首次将自适应逆控制用于电力有源滤波器.将系统的主电路部分及有源滤波器看作广义有源滤波器,通过自适应逆控制方式控制直流电容电压,使其输出跟随参考输入,最终达到抑制谐波和补偿无功的目的.此检测算法简单有效,稳态和暂态的仿真结果均证实了该算法的可行性.     

光栅检测系统温度误差的补偿方法

温度误差是影响检测系统精度的重要因素。重点论述了环境温度的检测过程 ,提出了利用单片机对温度误差进行补偿的系统结构与原理。最后给出实验结果     

一种谐波电流的检测方法

采用小波变换对电力系统中的谐波电流进行滤波,对检测出的基波电流进行了误差分析。小波变换具有良好的时频局部化特性,克服了传统FFT法仅有频域局部化的缺点,对于闪变信号十分敏感。仿真结果表明,此方法可以很好地跟踪时变谐波,准确检测出闪变电流信号,可以满足有源滤波器(APF)的实时检测要求。     

低通滤波器对谐波电流检测的影响分析

研究了基于瞬时无功功率理论的一种谐波电流检测方法,利用MATLAB仿真软件建立相应的仿真模型,并对其中的低通滤波器关于谐波电流检测效果的影响进行了仿真研究.仿真结果表明,低通滤波器的类型、截止频率和阶数对检测电路的检测精度、动态响应具有显著的影响.通过对仿真结果的分析,低通滤波器选择截止频率为20Hz,阶数为2次就可以有效地检测谐波.     

基于谐波电压检测的矿用混合型电力滤波器的研究

混合型电力滤波器由无源滤波器和有源滤波器通过不同的连接方式构成。根据煤矿电网谐波源特性选择了适用的混合型电力滤波器拓扑方式 ,针对其中的有源滤波器部分设计了基于电压检测的谐波电流获取方法 ,并由此构造了电路模型。经仿真实验分析 ,证实该方案具有优良的谐波抑制特性 ,该设计思路和方法是可行的。     

基于瞬时无功功率的改进型谐波电流检测方法

三相瞬时无功功率理论,结合电机分析理论中的旋转坐标系思想(Park变换),改进了传统的i_p-i_q运算方式,把三相电流置于旋转坐标系中进行改进,进而提出了一种改进型谐波电流检测方法.新方法利用基波分量与谐波分量的不同特性,在旋转坐标系中对基波分量和谐波分量进行分离,求得谐波旋转分量,然后对分量进行反变换便可直接得到静止坐标系中需要检测的三相谐波电流.仿真结果表明,不论负载电流突变与否,改进型检测方法比传统方法的响应速度更快,检测精度更高.     

镀液pH值微机检测系统的研究

本文介绍了以ＭＣＳ－５１系列单片微机为核心的镀液ｐＨ值检测系统的基本原理，并对系统的硬件构成、软件设计和抗干扰措施等有关问题进行了详细介绍。     

基于异常值检测的KCF目标丢失预警方法研究

当目标受尺度变化、严重遮挡、相似目标干扰、光照变化和出视野等因素影响时,核相关滤波器（KCF）跟踪算法会出现目标丢失现象。目标一旦丢失,KCF跟踪算法本身是不能察觉的,并且跟踪器会将背景信息作为目标继续进行跟踪,导致目标彻底丢失。针对这一问题,在KCF跟踪算法的基础上,提出了一种基于异常值检测方法的目标丢失预警机制。该方法利用一组固定维数动态峰值数据的均值和标准差对每帧的响应峰值进行检测,如若发现异常峰值,则判定目标丢失或即将丢失,解决了KCF跟踪器在跟踪过程中目标丢失不能察觉的问题。实验结果表明,所提出的方法在KCF算法跟踪过程中目标丢失时,能够正确预警,成功率达到100%,具有很高的可靠性,为目标丢失后何时载入目标重检测定位提供可靠的依据。     

采用异常值检测及重定位改进的KCF跟踪算法

针对传统核相关滤波器（KCF）跟踪算法受光照变化、严重遮挡和出视野等因素影响,出现目标丢失现象时,跟踪器会将背景信息作为目标继续进行跟踪而不能重新定位目标的问题,在KCF的基础上,引入异常值检测方法作为目标丢失预警机制,同时,提出了目标丢失重检测定位机制。方法对每帧的峰值进行检测,发现异常峰值,则判定目标丢失或即将丢失,预警机制发出警告,停止目标模板更新,启动目标丢失重检测定位机制,在全帧搜索定位目标。实验结果表明,改进的算法精确度为0.751,成功率为0.579,较之传统KCF跟踪算法分别提高了5.77%和12.43%。解决KCF跟踪器在目标丢失后不能重新找回目标继续跟踪的问题,提升了跟踪算法的性能,实现了长期跟踪。     

一类非线性系统准滑模控制的稳态误差分析

针对一类具有未知控制增益的不确定非线性系统准滑模跟踪控制,通过分析跟踪误差和滑模变量之间的关系,利用有界输入有界输出稳定的思想,分别推导了采用Slotine形式的传统滑模面和传统积分滑模面时系统的稳态跟踪误差的界.将其与现有的几种方法进行比较,该方法求得的稳态跟踪误差界更精确.根据给定的稳态跟踪误差要求,可设计出适合抑制抖振的饱和函数.通过仿真算例验证了所提出方法的有效性.     

Fault accommodation for uncertain linear systems with measurement errors

This paper investigates the observer based fault accommodation (FA) problem for linear systems with state perturbations and measurement errors. A novel intermediate estimator is proposed to estimate the state and the faults simultaneously, where the effect of state perturbations and measurement errors can be effectively eliminated by fully exploiting the design freedom of some specified parameters. Based on the estimation, a fault tolerant control (FTC) scheme is synthesized. It is proved that the states of the resulting closed loop system are uniformly ultimately bounded with an explicit bound. Simulation examples verify the effectiveness of the proposed method. Copyright © 2016 John Wiley & Sons, Ltd.     

Decentralized stabilization of Markovian jump interconnected systems with unknown interconnections and measurement errors

This paper investigates the decentralized output feedback control problem for Markovian jump interconnected systems with unknown interconnections and measurement errors. Different from some existing results, the global operation modes of all subsystems are not required to be completely accessible for the decentralized control system. A decentralized dynamic output feedback controller is constructed using neighboring mode information and local outputs, where the measurement errors between actual and measured outputs are considered. Subsequently, a new design method is developed such that the resultant closed‐loop system is stochastically stable and satisfying an L_∞‐norm constraint. Sufficient conditions are formulated by linear matrix inequalities, and the controller gains are characterized in terms of the solution of a convex optimization problem. Finally, an example is given to illustrate the effectiveness of the proposed theoretical results.     

传感器测量误差下的非线性车辆队列控制

传感器测量误差对车辆队列的有效控制与稳定性造成了较大的影响;通常情况下,大多研究成果将传感器测量误差设定为分布规律已知的随机数列(如高斯分布,泊松分布等),以便采用特定的数理方法消除误差影响;然而对于控制系统中仅满足有界条件的测量误差,仍需开展进一步的深入研究;针对此类现状,以非线性车辆队列控制为研究对象,综合考虑车载传感器的有界测量误差与车辆之间的有向通信拓扑,设计一种基于滑模的车辆队列控制方法;该方法能有效解决有界传感器测量误差下的车辆队列控制问题;此外,在控制过程中利用预设性能控制(PPC,prescribed performance control)理论,进一步约束车辆队列跟踪误差,确保车辆队列的队列稳定性;最后,通过数值仿真的方式验证本文所提出控制算法的有效性和可行性。     

光电轴角编码器的细分误差快速测量系统

为了在野外快速准确地测量编码器的误差,研制了编码器的误差测量系统。因为编码器的误差主要来自细分误差,该系统主要对细分误差进行分析。系统采用2片MAX125 A/D转换芯片对编码器输出的信号进行采集,通过并口将数据传给计算机进行误差分析。与传统的误差测量系统相比具有测量速度快、便携、简单等特点。利用该系统对某21位编码器的误差进行测量分析,证明该方法可行。     

On robustness of constrained discrete-time systems to state measurement errors

In this note we show that robustness with respect to additive disturbances implies robustness with respect to state measurement errors and additive disturbances for a class of discrete-time closed-loop nonlinear systems. The main result is formulated in terms of input-to-state stability and includes the possible presence of input and state constraints. Moreover, the state feedback controllers are allowed to be discontinuous and set-valued and thus the result also applies to model predictive control laws.     

Effects of measurement errors on psychometric measurements in ergonomics studies: Implications for correlations,ANOVA, linear regression,factor analysis,and linear discriminant analysis

This paper aims to demonstrate the effects of measurement errors on psychometric measurements in ergonomics studies. A variety of sources can cause random measurement errors in ergonomics studies and these errors can distort virtually every statistic computed and lead investigators to erroneous conclusions. The effects of measurement errors on five most widely used statistical analysis tools have been discussed and illustrated: correlation; ANOVA; linear regression; factor analysis; linear discriminant analysis. It has been shown that measurement errors can greatly attenuate correlations between variables, reduce statistical power of ANOVA, distort (overestimate, underestimate or even change the sign of) regression coefficients, underrate the explanation contributions of the most important factors in factor analysis and depreciate the significance of discriminant function and discrimination abilities of individual variables in discrimination analysis. The discussions will be restricted to subjective scales and survey methods and their reliability estimates. Other methods applied in ergonomics research, such as physical and electrophysiological measurements and chemical and biomedical analysis methods, also have issues of measurement errors, but they are beyond the scope of this paper. As there has been increasing interest in the development and testing of theories in ergonomics research, it has become very important for ergonomics researchers to understand the effects of measurement errors on their experiment results, which the authors believe is very critical to research progress in theory development and cumulative knowledge in the ergonomics field.     

Target tracking with fast adaptive revisit time based on steady state IMM filter

Time is a valuable resource in phased-array radar and proper use of it enables the radar to track more targets simultaneously. Appropriate usage of time in the tracking means the radar can minimize the revisit rate of the tracked targets while the accuracy of targets position estimation is still acceptable. In this paper, a new method for determination of target revisiting time is proposed which has relatively low computational cost and uses steady state filters with Interactive Multiple Models structure. The proposed algorithm allows the radar designer to determine the filter parameters by some criteria such as the desired accuracy and targets maneuver. The performance of the proposed method is compared with the conventional filters for standard maneuverable flying targets. Simulations show the better accuracy and reliability of the proposed method beside its less target revisit time and computational load.     

Transient response comparison of feedback and feed‐forward compensation methods in systems with zero steady state error

Proportional–Integral–Derivative (PID) controllers with integral action are conventionally used as feedback controllers. They are used to obtain zero steady‐state error when the reference input or the disturbance are steps and where zero‐type systems (i.e. with no poles at the origin) are controlled. The controller meets its objective when the controlled system is non linear, but usually introduces undesirable changes in the dynamics that must be compensated by readjusting the proportional gain. In this paper, we compare PID with two alternative techniques based on the use of a feed‐forward system and a multiple feedback system, respectively. A detailed comparison of the transient response obtained with these methods is presented and validated with some simulation examples.     

Stubborn state estimation for nonlinear distributed parameter systems subject to measurement outliers

In this article, the state estimation problem is investigated for a class of distributed parameter systems (DPSs). In order to estimate the state of DPSs, we give a partition of spatial interval with a finite sequence and, on each subinterval, one sensor is placed to receive the measurements from the DPS. Due to the unexpected environment changes, the measurements will probably contain some outliers. To eliminate the effects of the possibly occurring outliers, we construct a stubborn state estimator where the innovation is constrained by a saturation function. By using Lyapunov functional, Wirtinger inequality and piecewise integration, some sufficient conditions are obtained under which the resulting estimation error system is exponentially stable and the performance requirement is satisfied. According to the obtained analysis results, the desired state estimator is designed in terms of the solution to a set of matrix inequalities. Finally, a numerical simulation example is given to verify the effectiveness of the proposed state estimation scheme.