共查询到20条相似文献，搜索用时 46 毫秒
1.
《Journal of The Franklin Institute》2019,356(15):8829-8854
The design, tuning, and implementation of controllers are crucial for the solutions to control problems. Generalized minimum variance control (GMVC) has attractive properties and it is widely used for controller performance enhancement. The measured signals of process output variables, which are used as feedback signals, are generally subject to measurement noise. However, the GMVC theory assumes the feedback signals are the process outputs, which rarely consider the unavoidable measurement noise. By additionally considering the measurement noise, the control performance of GMVC with the measurement noise is analyzed in this paper. The dynamic data reconciliation (DDR) method, which uses the information of both the process model and the measurement data to reconcile the measured signals, is introduced. It is combined with GMVC to reduce the effect of the measurement noise on the results of GMVC. The effectiveness of GMVC combined with DDR is illustrated in two case studies, where the proposed method is compared with the original GMVC and the GMVC with the conventional digital filter. The results in both SISO and MIMO control systems show that the proposed GMVC combined with DDR can reduce the effect of the measurement noise and achieve better control performance. 相似文献
2.
Operational matrix based set-membership method for fractional order systems parameter identification
《Journal of The Franklin Institute》2021,358(18):10141-10164
In this paper, a new method is proposed to identify the coefficients and differentiation orders of fractional order systems with measurement noise. The proposed method combines the operational matrix method and the set-membership method. First, the block pulse functions operational matrix of the fractional differentiation is used to convert the fractional order system to an algebraic system. Then, the coefficients and differentiation orders are simultaneously estimated through a nest loop optimization process, where the optimal bounding ellipsoid set-membership algorithm is utilized to estimate the system’s coefficients and the orders are estimated with the interior-point method. The proposed method can accurately estimate the coefficients and differentiation orders of fractional order systems under any bounded measurement noise with less computational effort. Experimental results demonstrate the effectiveness of the proposed method. 相似文献
3.
介绍了单相正弦脉宽调制逆变器的工作原理和利用集成脉宽调制器SG3525产生SPWM波的方法，给出了样机实验的结果。 相似文献
4.
《Journal of The Franklin Institute》2022,359(18):10726-10740
In this paper, the secure transmission issue of a remote estimation sensor network against eavesdropping is studied. A powerful eavesdropper overhears the measurement data sent through the communication channels between the sensors and the remote estimator, and estimates system state illegally, which threatens the system information security. Different from the existing anti-eavesdropping design approaches, a stealthy artificial noise (AN) strategy is proposed to prevent eavesdroppers from deciphering encryption policy by hiding the encryption process from eavesdroppers. It has the same dynamical process with each sensor’s measurement to guarantee that the estimation error of the eavesdropper is unbounded while its observation residual variance keeps in certain bound and converges to 0, and further ensure system security without alerting the eavesdropper. It is proved that the strategy is feasible whenever the eavesdropper starts to wiretap. The selection of sensors that needs to be encrypted is further given by solving an optimization problem. The effectiveness of the proposed algorithm is verified by two simulation examples. 相似文献
5.
《Journal of The Franklin Institute》2022,359(8):3930-3950
Control performance of the industrial process is inevitably influenced by the measurement noises and non-Gaussian external disturbances. This influence has not been fully considered in the traditional variance-based controller design. To reduce the influence, a novel scheme that can enhance the control performance is developed by integrating dynamic data reconciliation (DDR) into minimum rational entropy control (MREC) in this paper. Firstly, the influence of measurement noise is fully considered, and a novel DDR method is proposed to deal with the minimum entropy control (MEC) process such that the influence of measurement noise can be reduced, and the control performance will be improved. Then, based on the DDR-MREC performance index, a benchmark for evaluating the control performance of non-Gaussian systems is established. Finally, the proposed control performance assessment (CPA) method is applied to the wind energy conversion system and compared with the CPA method based on DDR-minimum variance control. The experimental results have demonstrated that the proposed new method is more effective than existing works. 相似文献
6.
For state estimation of high accuracy, prior knowledge of measurement noise is necessary. In this paper, a method for solving the joint state estimation problem of jump Markov nonlinear systems (JMNSs) without knowing the measurement noise covariance is developed. By using the Inverse-Gamma distribution to describe the dynamics of measurement noise covariance, the joint conditional posterior distribution of the state variable and measurement noise covariance is approximated by a product of separable variational Bayesian (VB) marginals. In the newly constructed approach, the interacting multiple model (IMM) algorithm, as well as the particle-based approximation strategy, is employed to handle the computationally intractable problem and the nonlinear characteristics of systems, respectively. An interesting feature of the proposed method is that the distribution of states is spanned by a set of particles with weights, while the counterpart of measurement noise covariance is obtained analytically. Moreover, the number of particles is fixed under each mode, indicating a reasonable computational cost. Simulation results based on a numerical example and a tunnel diode circuit (TDC) system are presented to demonstrate that the proposed method can estimate the measurement noise covariance well and provide satisfied state estimation when the statistics of the measurement are unavailable. 相似文献
7.
介绍了一种两相步进电机细分控制蠕动泵系统。单片机作为主控芯片,细分控制通过单片机产生正弦波信号进行脉宽调制（PWM）实现,脉宽调制（PWM）采用电流跟踪型SPWM方案。该设计提高了步进电机控制蠕动泵的稳定性及测量精度,整个系统成本低廉,实时性好。 相似文献
8.
《Journal of The Franklin Institute》2022,359(11):5682-5711
This work presents an iterative concept of the State-space Realization Algorithm with Data Correlation (SSRA-DC) to identify MIMO systems with measurement noise and subjected to a reduced number of samples acquired from the process. The measurement noise is characterized as a random signal with properties of white noise and having up to 1% of the output signal amplitude. The proposed technique is based on the Markov parameters matrix’s feedback in an iterative algorithm supported by the SSRA-DC method. A gain factor takes part in the closed-loop to update the Markov parameters matrix, reducing their residues at each iteration. A fixed value for the gain is applied all over the iterations. The Gaussian White Noise (GWN) is employed as the input excitation signal in simulated experiments of mass-damper-springer models with 50 and 100 degrees of freedom. For some algorithm settings, one hundred simulations, each holding more than 100 iterations, are performed to statistically demonstrate the iterative algorithm’s effectiveness compared to the conventional SSRA-DC. Further comparative analysis is accomplished between the iterative method with the ARMAX and N4SID algorithms. 相似文献
9.
《Journal of The Franklin Institute》2023,360(9):6515-6536
The performance of the current state estimation will degrade in the existence of slow-varying noise statistics. To solve the aforementioned issues, an improved strong tracking maximum correntropy criterion variational-Bayesian adaptive Kalman filter is presented in this paper. First of all, the inverse-Wishart distribution, as the conjugate-prior, is adopted to model the unknown and time-varying measurement and process noise covariances, then the noise covariances and system state are estimated via the variational Bayesian method. Secondly, the multiple fading-factors are obtained and evaluated to modify the prediction error covariance matrix to address the problems associated with inaccurate error estimation. Finally, the maximum correntropy criterion is employed to correct the filtering gain, which improves the filtering performance of the proposed algorithm. Simulation results show that the proposed filter exhibits better accuracy and convergence performance compared to other existing algorithms. 相似文献
10.
研究了一种扩谱载波数字脉冲间隔调制SSC—DPIM(Spread spectrum carrier digital pulse interval modulation)技术并用于电力线载波扩谱通信系统．采用线性扫频SSC扩谱载波对DPIM符号进行编码，引入脉冲前导码作为传输数据块的同步信号以防止差错传播．介绍了数据传输速率及数据块传送差错率的理论分析结果．并采用单片机实现了SSC-DPIM电力线载波通信系统．实验结果表明，在同样的电力线网络环境下，其通信效果明显优于已有的电力线载波通信系统。 相似文献
11.
This paper discusses the parameter estimation for a class of bilinear-in-parameter systems with colored noise. By utilizing the filtering technique, we derive the relationship between the filtered output and the measurement output and obtain two linear regressive sub-models. A filtering based multi-innovation stochastic gradient algorithm is derived for interactively identifying each sub-model. The proposed algorithm avoids the estimation of correlated noise and improves the parameter estimation accuracy by making full use of the measurement data. The numerical simulation results indicate that the proposed algorithm has higher estimation accuracy than the hierarchical multi-innovation stochastic gradient algorithm. 相似文献
12.
The identification of linear, discrete time, scalar output systems which are driven exclusively by white, zero mean, inaccessible noise sequences is discussed. Two principal results are presented. First, two methods (least squares and an autocorrelation technique) for identifying the system characteristic equation coefficients are compared. The least squares approach is shown to be biased except for special cases. In general, the bias cannot be removed. If the state transition matrix is of the phase variable form, bias removal requires a knowledge of the measurement noise variance and all but one of the state driving noise variances. The autocorrelation technique is not biased asymptotically and does not require a knowledge of the noise variances.Secondly, it is shown that the m2 elements of the state transition matrix cannot be identified uniquely from the scalar output sequence autocorrelation coefficients if the system order is higher than one. The implication of this uncertainty in the state transition matrix on optimal filtering of the output sequence is briefly discussed. 相似文献
13.
研究振弦式传感器频率测量问题。针对振弦式传感器输出信号微弱、容易受到干扰而造成的测量精度下降问题,提出了一种基于锁相环的新型测频电路,论证了锁相环在电路中在抑制噪声以及提高测频精度的有效作用。锁相环技术用于振弦式传感器测频系统中具有良好的稳态精度和较高的动态性能。 相似文献
14.
冲击信号是一种瞬态信号,对其进行采集和分析需要提供完善的信号触发控制、采样频率自动设置及采样点数自动控制等功能。本文在分析了实现冲击信号采集特点及原理的基础上,研究并设计了基于CPLD(复杂可编程器件)的硬件功能模块。文中在生成系统时钟上采用了基于有限状态机的方法,完全在CPLD芯片中实现分频,取代了常见的使用8254可编程芯片的做法。此外,在模块中设计了采样频率设置、采样点数自动计点等功能,同时还可以用硬件实现多通道信号自动触发的功能,可以实现超前触发、滞后触发、电平触发、沿触发、触发电平自动设置等功能。所有的触发逻辑都使用verilog硬件描述语言在CPLD芯片中实现。通过和A/D电路配合工作,硬件模块可以实现采样的自动化。 相似文献
15.
Noise Induced Tracking Error (NITE) refers to the tracking error of the mean of the output in feedback control systems with nonlinear instrumentation subject to zero-mean measurement noise. Most of the previous work rely on the stochastic averaging for NITE analysis, the validity of which requires that the bandwidth of the zero mean measurement noise is much higher than that of the system. This is because the results obtained by stochastic averaging are asymptotic with respect to the noise bandwidth. Due to the asymptotic nature of the analysis tool, it is not straightforward to provide a quantitative argument for high bandwidth. An alternative method in the literature that can analyze NITE is stochastic linearization for random input, which is analogous to the well known describing function approach for sinusoidal input. Unlike stochastic averaging, stochastic linearization is not an asymptotic approximation. Therefore, analysis can be carried out for any given noise bandwidth. We carry out NITE analysis using stochastic linearization for a class of LPNI systems that are prone to NITE; identify the system conditions under which the averaging analysis of NITE may yield inaccurate results for a finite noise bandwidth; and prove that the results from the two methods agree as the noise bandwidth approaches infinity. In addition, an existing NITE mitigation strategy is extended based on the proposed method. Numerical examples are given to illustrate the results. 相似文献
16.
The coordinated tracking problem where a group of followers intercepts a dynamic leader is studied. It is shown in this paper that reduction of inter-agent communication is obtained and improved performance is achieved when each follower implements dynamical models of neighbors and by using an event-triggered control strategy that requires each agent to send measurement updates only when necessary. The results in this paper consider directed graphs and the possible existence of cycles. Performance bounds on the tracking error have been obtained, which are functions of the communication topology and the event thresholds. This approach is extended to consider measurement noise and similar bounds are presented for this case. 相似文献
17.
Chao Ai Wei Gao Lijuan Chen Jiawei Guo Xiangdong Kong Andrew Plummer 《Journal of The Franklin Institute》2021,358(1):296-320
The requirement for An electrical grid-connected wind turbine is that the synchronous generator speed is stable within a required speed range for the electrical grid. In this paper, a hydraulic wind turbine (HWT) system is considered, and the working principle and working conditions of the HWT are introduced. A novel speed control method is proposed in this paper, using both a proportional flow control valve and a variable displacement motor, which are adjusted in combination to control the speed of the HWT. By establishing a state space model of the HWT and solving the nonlinear system with a feedback linearization method, a bivariate tracking controller is constructed to realize accurate speed control under fluctuating wind speed and the load disturbance conditions. The effectiveness of the control method is verified by simulation, but experimental results highlight problems with the method. The theoretical controller is simplified to reduce sensitivity to measurement noise and modeling error. The control effect has been improved to some extent, but it is limited. Based on these results, combined with the sliding mode variable structure control method and the feedback linearization method to solve the problem of measurement noise and modeling error, and the effectiveness of the control law is finally verified experimentally. It lays a theoretical foundation for the practical application of HWT. 相似文献
18.
基于主成分分析的R＆D绩效评价系统 总被引：8，自引：0，他引：8
设计了一套R&D绩效评价指标模型与方法,从一个全新的角度运用主成分分析法,在第一阶段,用较少的、彼此间不相关的绩效综合指标整合众多的、彼此间存在较大相关性的实测绩效指标;在第二阶段,以各绩效综合指标的方差贡献率作为权重,对之加权求和以求得R&D绩效的总评得分.结合对随机抽取的20家高新技术企业的R&D绩效评价的实证分析,切实地说明了该模型与方法在对各指标客观地赋予权重和对企业R&D绩效分级评价时具有极大的优越性. 相似文献
19.
Some new techniques for initial alignment of strapdown inertial navigation system are proposed in this paper. A new solution for the precise azimuth alignment is given in detail. A new prefilter, which consists of an IIR filter and a Kalman filter using hidden Markov model, is designed to attenuate the influence of sensor noise and outer disturbance. Navigation algorithm in alignment is modified to feedback continuously for the closed-loop system. It is shown that the initial estimated variance setting of azimuth angle error can influence the speed of initial alignment significantly. At the beginning of alignment, Kalman filter must make a very conservative guess at the initial value of azimuth angle error to get a high convergent speed of the azimuth angle. It is pointed out that the low signal to noise ratio makes the ordinary setting of the estimated azimuth variance slow down the convergent speed of the azimuth angle. Also is shown that the large azimuth angle error problem can be solved well by our solution. The feasibility of these new techniques is verified by simulation and experiment. 相似文献
20.
Giorgio V. Borgiotti 《Journal of The Franklin Institute》1977,303(2):155-175
An optimal procedure is established for the reconstruction of the angular object distribution in a given field of view (FOV). The object is coherently illuminated and located in the far zone of the receiving aperture. The procedure is “uniformly” optimal in the sense of minimizing the statistical r.m.s. difference between the object distribution, modeled as a random function of the angular coordinates and its reconstructed image, for each direction belonging to the FOV. The observable complex amplitude distribution of the field on the aperture is due in the general case not only to the incidentfield scattered by the object but also to background disturbance, or “angular noise”, randomly distributed inside and outside the FOV, and is affected by “measurement noise”, that is random errors introduced in measuring the aperture field. The reconstruction algorithm consists of summing a truncated series of special functions—prolate spheroidal for the linear case and their generalizations for two dimensional apertures—weighted by appropriate coefficients. These coefficients depend upon the observed aperture field and upon the relative power densities associated with the object field and the various types of noise. The series is truncated to a number of terms (“effective degrees of freedom” of the image) determined through an information theoretical method: each term of the series, suitably ordered, provides an information gain less than the preceding one, and the information gain goes rapidly to zero. A relationship between information transfer and mean squared error for each term in the image series is established. Numerical examples are discussed. 相似文献