基于FLOCC-ESPRIT的极化阵列参数估计方法

针对基于分数低阶矩类阵列波达方向(DOA)估计方法仅适用于独立同分布(i.i.d)SαS背景噪声的缺点,提出了一种线性极化阵列DOA和极化参数联合估计的分数低阶循环相关(FLOCC)极化参数联合估计(ESPRIT)算法。该方法首先利用入射信号的循环平稳特性,采用分数低阶循环相关函数抑制α和高斯混合噪声及与信号循环频率相异的任何循环平稳干扰信号。在此基础上,利用阵列信号参数与噪声子空间的正交性,采用ESPRIT算法直接求取了信号的DOA和极化参数。该方法对于α和高斯混合噪声及与信号循环频率相异的任何循环平稳干扰信号具有很强的抑制能力。即使对于空域内靠得非常近的信源,该方法也可利用极化信息的差异进行区分。实验结果表明,在α和高斯混合信噪比(SNR)为0 d B,信干比(SIR)为3 d B时,其DOA和极化参数估计的均方根误差分别为0.23°和0.54°;并且在实测数据环境下,当SNR为10 d B时,本文算法仍然有效。     

混沌噪声背景下周期小信号频率估计新方法

利用待测小信号的周期性及混沌信号的相关特性,提出一种将倍频法与经验模式分解法相结合的混沌噪声背景下周期小信号频率估计的新方法.首先利用相关法对原始混合信号进行初步去噪处理,再利用倍频法与经验模式分解法对信号进行自适应分解,最后对分解出来的固有模态函数进行交叉功率谱分析,估计出周期小信号频率.该方法适用于强混沌信号与强观测噪声为背景的周期小信号频率估计.仿真实验结果表明,方法简单有效,计算量小.     

A simple and precise real-time four point single sinusoid signals instantaneous frequency estimation method for portable DSP based instrumentation

A simple and precise instantaneous frequency estimation method of single sinusoid signals, using four equal spaced samples, for portable DSP based instrumentation is proposed. An analytical formula is obtained. Four-point instantaneous frequency estimator is sensitive to deviation of the sampling rate and quantization noise. As a demonstration of its simplicity, by implementing the proposed algorithm, a DSP based instantaneous frequency meter was built and tested with satisfactory performance.     

A fast,simple and accurate time-varying frequency estimation method for single-phase electric power systems

This paper presents a simple and accurate method to estimate time-varying frequency for single-phase electric power systems, based on three equally spaced samples. A sinusoidal voltage signal model, without dc offset, with time-varying frequency was assumed. Analytical formulas are derived. The method shows good estimation accuracy over a real world wide range of frequency changes. Simulations have been performed.     

FFT+FT离散频谱校正法参数估计精度

研究用FFT谱连续细化傅里叶变换分析法进行离散频谱校正时的参数估计误差。分析无噪声情况下频率﹑相位﹑幅值的估计误差随细化倍数的变化规律,估计精度随细化倍数的增大而提高,当细化倍数大于40时,最大估计误差几乎可忽略不计。在高斯白噪声的影响下,细化后频谱序列最大值找错的概率随细化倍数的增加而增加,综合考虑频率分辨率对频率估计精度的影响及频谱序列最大值找错的概率,提出用归一化频率估计综合误差和归一化频率估计最大可能误差两个指标评价此校正法对频率的估计精度,并基于此给出不同信噪比条件下的最优细化倍数。采用非线性最小二乘拟合法对噪声影响下的FFT谱连续细化傅里叶变换分析校正法进行改进,通过仿真模拟验证改进后该校正方法具备更高的校正精度和抗噪能力。     

非线性航空发动机性能参数估计方法研究

为了消除线性模型误差的影响,建立了航空发动机性能变化参数非线性估计的模型,提出了一种非线性的航空发动机部件性能变化参数估计的方法。将待估计参数以及模型计算值和实际测量值之间的误差一同并入发动机模型程序进行求解。仿真结果表明,与线性估计方法相比,非线性参数估计的方法具有更高的精度和更简单的系统结构。     

时变信号频率跟踪的一种新自适应陷波器方法

针对频率、幅值和相位均发生变化的时变信号,现有自适应陷波器(ANF)频率估计方法存在信号频率跟踪精确性和稳定性不足的问题,为此提出了一种基于新误差函数的ANF时变信号频率跟踪方法,通过新误差函数改善自适应算法收敛至最优频率解的精度与速度,以提高时变信号频率跟踪的精确性和稳定性。给出了新误差函数分析结果,新ANF方法实现步骤和该频率估计方法的Cramer-Rao下限。通过计算与现有ANF的时变信号频率跟踪方法性能进行了比较分析,并针对科里奥利质量流量计时变信号进行了现场实验验证。结果表明,该方法具有收敛速度快、跟踪精度高、更接近Cramer-Rao下限和抗噪性好的优点。     

Constitutive parameter estimation of a viscoelastic model with internal variables

The present work is aimed at estimating the constitutive parameters of viscoelastic materials. The constitutive equation addressed takes internal dissipation into account by means of internal variables. The identification method is built on an optimization problem where the minimum of an error function is sought. The error function is based on the difference between the experimental response and the model one and on the parameter constraints as well. The constitutive parameters are estimated by means of a modified Levenberg–Marquardt algorithm. The viscoelastic material characterization was assessed through an experimental set-up consisted of a sandwich beam with a viscoelastic core.     

A study on the parameter estimation of DURUMI-II for the fixed right elevator using flight test data

The stability and control derivatives of DURUMI-II UAV using the flight test are obtained. The flight test data is gathered from the normal flight condition (normal mode) and the flight condition assumed as the right elevator fixed (fault mode). Using real-time parameter estimation techniques, applied to Fourier transform regression method, simulates the aircraft motion. From the result, the fault of control surface is to be detected. In this paper, the results of the real-time parameter estimation techniques are compared with the results of the Advanced Aircraft Analysis (AAA). Using the aerodynamic derivatives, it provides the base line of normal/failure for the control surface by using the on-line parameter estimation of Fourier transform regression. In flight, this approach maybe helpful to detect and isolate the fault of primary control surface. It is explained how to perform the flight condition assumed as the right elevator fixed in the flight test. Also, it is mentioned how to switch between the normal flight condition and the assumed fault flight condition.     

离合器从动盘测试机控制系统建模及其参数估计

提出了一种离合器从动盘测试机位置控制系统模型参数估计方法.通过分析系统各个环节建立了系统简化数学模型;采用最小二乘法对模型参数进行估计.经仿真实验验证,辨识参数模型能较好的反映了系统开环特性;应用复合形法求解该优化问题,提高了求解速度.     

A quadratic polynomial signal model and fuzzy adaptive filter for frequency and parameter estimation of nonstationary power signals

Accurate estimation of amplitude, phase and frequency of a sinusoid in the presence of harmonics/inter harmonics and noise plays an important role in a wide variety of power system applications, like protection, control and state monitoring. With this objective, the paper presents a novel hybrid approach for the accurate estimation of dynamic power system frequency, phasor and in addition to suppressing the effect of harmonics/interharmonics and noise in the voltage and current signals. The algorithm assumes that the current during a fault occurring on a power system consists of a decaying dc component, and time variant fundamental and harmonic phasors. For accurate estimation of fundamental frequency, phasor, decaying dc and ac components in the fault current or voltage signal, the algorithm uses a quadratic polynomial signal model and a fuzzy adaptive ADALINE filter with a modified Gauss–Newton algorithm. Extensive study has been carried out to demonstrate the performance analysis and fast convergence characteristic of the proposed algorithm. The proposed method can also be implemented for accurate estimation of dynamic variations in the amplitude and phase angles of the harmonics and inter harmonics mixed with high noise conditions.     

Automated system for determining frequency dependent parameter model of transmission line in a laboratory environment

This work presents an automated system for determining transmission line model parameters at various frequencies. The system was developed and implemented on General Electric test reactors designed to model power transmission line behavior in a laboratory environment. The measurement system and data processing are controlled and automated via custom developed LabVIEW software. Measurements are obtained from voltage and current probes interfacing with oscilloscopes. This data is then acquired and processed in LabVIEW software. The structure of the transmission line model, desired confidence level and number of tests to conduct are specified user inputs. The system subsequently provides the transmission line impedance parameters based on these specifications. These parameters are calculated using both time domain and frequency domain techniques. While this work focuses on determining transmission line model parameters, this automated test measurement system is applicable to any device that can be parameterized via a current–voltage (I–V) characteristic or frequency response.     

离散频谱能量重心法频率校正精度分析及改进

研究噪声对离散频谱能量重心法的频率校正精度的影响,推导了在高斯白噪声背景下用能量重心法对加对称窗的离散频谱进行校正的频率误差理论公式,分析找错和找对最大值谱线情况下的理论误差和某些情况下校正误差较大的原因,为了提高能量重心校正法的频率校正精度,提出用谱线间相位差为阈值作为选择用3条或4条谱线进行校正依据的改进措施。通过对加Hanning窗的离散频谱进行计算机仿真计算,结果表明在大噪声背景下改进的能量重心校正法有很高的频率校正精度,与理论推导十分吻合,验证了理论推导的正确性,表明改进后的能量重心法具有更高的抗噪性能,扩大了能量重心校正法的工程应用范围。     

Persistently-exciting signal generation for Optimal Parameter Estimation of constrained nonlinear dynamical systems

This work presents a novel methodology for Sub-Optimal Excitation Signal Generation and Optimal Parameter Estimation of constrained nonlinear systems. It is proposed that the evaluation of each signal must also account for the difference between real and estimated system parameters. However, this metric is not directly obtained once the real parameter values are not known. The alternative presented here is to adopt the hypothesis that, if a system can be approximated by a white box model, this model can be used as a benchmark to indicate the impact of a signal over the parametric estimation. In this way, the proposed method uses a dual layer optimization methodology: (i) Inner Level; For a given excitation signal a nonlinear optimization method searches for the optimal set of parameters that minimizes the error between the outputs of the optimized and benchmark models. (ii) At the outer level, a metaheuristic optimization method is responsible for constructing the best excitation signal, considering the fitness coming from the inner level, the quadratic difference between its parameters and the cost related to the time and space required to execute the experiment.     

基于脉冲响应消岐重构的 UWB 测距优化方法

UWB 测距技术因功耗低、安全性高等优势在工业领域应用日益广泛。 工业非视距场景下 UWB 脉冲信号由于穿透衰 减和多通道反射等因素,存在首径信号衰减和多径延迟的问题,将会降低系统的定位精度。 针对该问题,通过对 UWB 信号传 递及响应建模,提出一种基于 UWB 信道脉冲响应的消岐重构算法,将信道脉冲簇信号进行泊松过程解析,对代表直线传播距 离的首径信号进行特征增强,实现了复杂多径干扰下的首径信号提取与分离,提高了信号到达时间辨识精度,减少了 UWB 测 距误差。 进一步地,依据 IEEE802015. 4a 标准对 UWB 信道响应进行仿真,并实现了不同遮挡环境下的实验研究,仿真和实验结 果表明,本文提出的消岐重构算法能够显著提高多干扰环境下的定位精度,在存在多反射源和多遮挡物的工业非视距场景下, 可使定位误差相较于传统阈值法降低约 79. 1% 。     

基于经验与变分混合分解的超声回波信号噪声消除方法

超声缺陷检测结果易受超声回波信号中复杂噪声的干扰,为了提高超声缺陷检测的准确度,提出一种基于混合分解的 超声回波信号噪声消除方法。 采用经验模态分解算法结合相关系数指标对超声回波信号进行预处理,得到消除低频噪声分量 的超声回波预处理信号。 基于变分模态分解将该预处理信号分解为一系列窄带本征模态函数,引入互信息指标估计变分模态 分解的最优模态数量,并根据窄带本征模态函数与预处理信号的相关系数提取有用的模态分量,实现对超声回波信号去噪结果 的重构。 通过仿真和实测超声回波信号验证了本文方法的去噪性能,并与现有方法进行了对比。 结果表明,本文方法可同时消 除超声回波信号中的高频和低频噪声,在不同信噪比条件下 EMD、VMD 和本文方法去噪结果的 SNR 均值分别为 10. 01、9. 48 和 16. 09 dB,验证了本文方法对于超声回波信号噪声消除的优越性。     

A novel method of Coriolis flowmeter phase difference measurement based on improved correlation analysis method

The shortcomings traditional phase difference extraction algorithms have such as being susceptible to noise interference, requiring full cycle conditions, leads to a decrease in phase difference extraction accuracy. To improve the accuracy of the phase difference extraction, two improved correlation analysis methods are proposed in this paper, one of which is based on the relationship between the extreme value of the cross-correlation function and the time difference, the other of which combines correlation analysis method with Hilbert transform. A simulation and experiment were set up to explore the influence of sequence length and signal-to-noise ratio on the extraction accuracy, as well as the influence of Kalman filtering. An experiment is set to compare the extraction mean error and variance of different algorithms under different phase differences. Experimental result shows that the improved algorithms have higher accuracy and stability. The feasibility of the two improved algorithms is verified.     

LIDFT method with classic data windows and zero padding in multifrequency signal analysis

This paper presents an advanced discrete Fourier transform linear interpolation method (LIDFT) using classic data windows and a zero padding technique that is well understood from its common use in spectrum analysis with FFT. This advancement of the LIDFT method allows for substantial improvement of its accuracy without deteriorating the condition of the initial location for sinusoidal components in the spectrum, as required in the traditional LIDFT method. Application of classic data windows instead of parametric data window specifically dedicated to the LIDFT method provides numerous opportunities for using this method in multifrequency signal analysis.     

基于FIR优化滤波的旋转高频信号注入法及其应用

针对传统旋转高频信号注入法中信号处理精度低、延时时间长及过程复杂等缺陷,提出一种基于有限冲激响应(finite impulse response,FIR)优化滤波的改进旋转高频信号注入法.该方法采用等纹波最佳逼近FIR滤波器提取高频电流信号,实现高频电流信号提取误差最小.通过对高频电流作外差处理,提取转子位置误差信号,省去旋转高频信号注入法中的同步轴系滤波单元,降低系统的复杂性.通过线性相位补偿,实现转子速度与位置估计最小延迟.构建无轴承永磁同步电机无速度传感器矢量控制平台,验证算法的有效性.仿真实验结果表明:通过离线优化设计FIR滤波器及线性相位补偿,该方法在全速范围内能够准确估计转子的位置与速度,与卡尔曼滤波相比,其估计精度更高,鲁棒性更强.     

A new method for measuring engine rotational speed based on the vibration and discrete spectrum correction technique

This paper presents an encoder-less method for measuring the rotational speed of a reciprocating engine. The proposed method obtains the rotational speed of the engine from the lowest harmonic frequency component of its vibration signals, and uses a discrete spectrum correction technique to improve the measurement precision. Results from bench tests and tests on real engines, each having a different number of cylinders, have proven that the proposed method can achieve an extremely high precision when the engine is working in a steady-state or small speed fluctuation condition. As compared to the encoder-based method for measuring engine rotational speed, which is often found in literatures, the proposed method uses a straightforward hardware which is easy to install, and is particularly suitable for use during routine inspection and maintenance of vehicles.