Adaptive synchronization and parameter identification of chaotic system with unknown parameters and mixed delays based on a special matrix structure

In this paper, we investigate the synchronization and parameter identification of chaotic system with unknown parameters and mixed delays. A new approach is proposed for designing a controller and a update rule of unknown parameters based on a special matrix structure, and the synchronization and the parameter identification are realized under the controller and the update rule. Numerical simulations are carried out to confirm the effectiveness of the approach. A significant advantage is that the process of designing a controller and a update rule become very clear and easy by the proposed approach.     

Real-time tracking control of electro-hydraulic force servo systems using offline feedback control and adaptive control

This paper focuses on an application of an electro-hydraulic force tracking controller combined with an offline designed feedback controller (ODFC) and an online adaptive compensator in order to improve force tracking performance of an electro-hydraulic force servo system (EHFS). A proportional-integral controller has been employed and a parameter-based force closed-loop transfer function of the EHFS is identified by a continuous system identification algorithm. By taking the identified system model as a nominal plant model, an H_∞ offline design method is employed to establish an optimized feedback controller with consideration of the performance, control efforts, and robustness of the EHFS. In order to overcome the disadvantage of the offline designed controller and cope with the varying dynamics of the EHFS, an online adaptive compensator with a normalized least-mean-square algorithm is cascaded to the force closed-loop system of the EHFS compensated by the ODFC. Some comparative experiments are carried out on a real-time EHFS using an xPC rapid prototype technology, and the proposed controller yields a better force tracking performance improvement.     

An intelligent instrument for tracking and adaptive filtering of oscillatory signals using Hebbian learning rules

In this paper Hebbian type of learning algorithms using total least squares method is applied for adaptive filtering techniques to remove the noise and undesired oscillatory signals at different systems. Here we have used the generalised Hebbian learning rules for initializing the internal representations of a feedforward neural network, which accelerates the convergence of supervised Hebbian learning rule. In case of constrained anti-Hebbian learning rule, the weight vectors of linear neuron unit is converged to an eigenvector which has the smallest eigenvalue. In the total least squares (TLS) method the noise rejection capability is superior to the least squares method. Here we have applied the initial sets of data for the internal representation of feedforward network which consists of bottom-up unsupervised learning process followed by top-down supervised learning process using total least squares (TLS) algorithm. For faster convergence we have included the momentum term for the updating of weights. An intelligent instrumentation scheme has been developed for on-line measurement of amplitude of oscillatory signals. The undesired oscillations of the signal is also removed by implementing neural network model (using Hebbian rules and total least square algorithm) on a digital signal processor.     

数字孪生驱动的航空发动机涡轮盘剩余寿命预测

为解决航空发动机涡轮盘剩余寿命在线预测难题,提出一种数字孪生驱动的涡轮盘剩余寿命预测方法。在建立数字孪生模型的过程中,首先,分析涡轮盘疲劳裂纹损伤机理,构建性能退化指标,建立涡轮盘性能退化过程的共性表征模型;其次,分析多种不确定性因素,采用状态空间模型建立涡轮盘性能退化过程的个性表征模型;然后,通过动态贝叶斯网络描述状态空间模型随时间的演化规律,建立涡轮盘性能退化过程的动态演化模型;最后,采用粒子滤波算法实现涡轮盘退化状态追踪和剩余寿命预测,从而完成涡轮盘性能退化数字孪生模型的建立。融合涡轮盘实时传感数据,通过贝叶斯推理实现对该数字孪生模型的动态更新。通过某型涡轮盘试验数据对该方法进行验证,结果表明该数字孪生模型能够较好地解决涡轮盘剩余寿命在线预测问题。     

[智能感知]基于粒子群优化支持向量机算法的行驶工况识别及应用

实车采集4种典型行驶工况数据,采用随机数法提取并扩充行驶工况识别训练及测试样本,利用多元统计理论对数据进行处理,基于粒子群优化的支持向量机(PSO-SVM)算法来进行行驶工况识别,分析了识别周期及更新周期对行驶工况在线识别精度的影响。将行驶工况识别技术应用在插电式混合动力汽车的能量管理策略中。仿真结果表明,相对于未采用行驶工况识别技术以及采用传统SVM算法进行工况识别的能量管理策略,基于PSO-SVM算法工况识别的能量管理策略使整车燃油经济性分别提高9.836%和4.348%,并且电池荷电状态(SOC)变化相对平稳,有利于提高系统效率和延长电池寿命。     

基于优化的元胞蚁群算法的无人飞行器动态路径规划方法

针对无人飞行器路径规划蚁群算法收敛速度慢,提出了一种新的蚁群算法。首先,以栅格为环境地图,在蚁群算法搜索过程中加入了圈形轨迹识别算法,避免了无人飞行器出现折返跑的现象。其次,采用最优路径进行信息素更新,减少了蚁群算法在搜索过程中产生的盲目交叉和“蚂蚁遗失”现象。最后,引入了无人飞行器轨迹的尖角优化策略,更好地模拟了无人飞行器的飞行特征。仿真实验表明,新算法具有更好的全局搜索能力。     

基于IIR结构的自适应滤波振动主动控制方法

当前自适应滤波前馈控制方法中具有代表性的是滤波-X最小均方(filtered-X least mean square,简称FX-LMS)算法,它通常假定干扰源可测且作为前馈控制器的参考输入,但实际振动控制过程中需要考虑控制输出反馈信号对参考信号的影响,因此滤波-X算法面向实际应用具有较大的局限性。针对这一问题,以机敏压电太阳能帆板结构为模拟试验对象,提出一种基于IIR(infinite impulse response,简称IIR)结构的滤波-U最小均方(filtered-U least mean square,简称FULMS)自适应滤波控制方法,着重分析了控制器结构设计、FULMS算法推理过程、试验模型结构设计、试验平台的构建及其试验验证等环节。经过与FXLMS算法对比仿真试验,笔者所设计的控制算法控制效果良好。将其进行试验验证分析,结果表明,所采用的控制器设计方法与控制算法收敛速度快,控制效果好,为自适应振动控制方法向实际工程应用提供了较好的研究基础。     

Recursive fuzzy c-means clustering for recursive fuzzy identification of time-varying processes

In this paper we propose a new approach to on-line Takagi-Sugeno fuzzy model identification. It combines a recursive fuzzy c-means algorithm and recursive least squares. First the method is derived and than it is tested and compared on a benchmark problem of the Mackey-Glass time series with other established on-line identification methods. We showed that the developed algorithm gives a comparable degree of accuracy to other algorithms. The proposed algorithm can be used in a number of fields, including adaptive nonlinear control, model predictive control, fault detection, diagnostics and robotics. An example of identification based on a real data of the waste-water treatment process is also presented.     

The application of the neural network on Morse code recognition for users with physical impairments.

Morse code is a simple, speedy and low cost means of communication composed of a series of dots, dashes and space intervals. Each tone element (either a dot, dash or space interval) is transmitted by sending a signal for a defined length of time. This poses a challenge as the automatic recognition of Morse code is dependent upon maintaining a stable typing rate. In this paper, a suitable adaptive automatic recognition method, combining the least-mean-square (LMS) algorithm with a neural network, was applied to this problem. The method presented in this paper is divided into five modules: space recognition, tone recognition, learning process, adaptive processing and character recognition. Statistical analyses demonstrated that the proposed method elicited a better recognition rate in comparison with other methods in the literature.     

基于异构值差度量的SOM混合属性数据聚类算法

针对传统聚类算法处理混合属性数据聚类质量不高且聚类结果可视化差的问题,提出了基于异构值差度量的自组织映射混合属性数据聚类算法。该算法以自组织映射神经网络为框架,采用基于样本概率的异构值差度量混合属性数据的相异性。利用分类特征项在Voronoi集合中出现频率作为分类属性数据参考向量更新规则的基础,通过混合更新规则实现数值属性和分类属性数据规则的更新。利用UCI公共数据库中的分类属性和混合属性数据集来测试所提出的聚类算法,并与SOM算法和kprototypes、SBAC、KL-FCM-GM算法进行比较。最后将所提出的聚类算法应用于轮式移动机器人的运动状态分析,获得了较好的聚类效果。     

非线性状态空间方法辨识电液伺服控制系统

针对回归神经网络辨识和建立非线性动态系统模型的问题,研究非线性状态空间描述的回归神经网络数学模型。讨论极小均方误差网络训练收敛准则,通过研究Kalman 滤波估计公式中的随机变量,提出一种参数增广的回归神经网络非线性状态方程,无导数的Kalman滤波器用于增广参数估计,人工白噪声强迫网络学习,更新网络权值,避免了扩展Kalman滤波器计算Jacobian信息和基于递度学习算法收敛慢的问题。在电液伺服系统辨识建模的应用中表明,回归神经网络较好地跟踪了液压油缸压力变化,与扩展Kalman滤波估计学习算法相比,新的算法具有较快的收敛和精度。     

A fuzzy-nets tool-breakage detection system for end-milling operations

This paper describes a new approach, the fuzzy-nets system, for monitoring tool breakage in end-milling operations. The fuzzy-nets tool-breakage detection (FNTBD) system has a self-learning capability to generate rule bases and to fine tune the term sets of each linguistic variable to the appropriate level of granularity. A self-learning algorithm for developing the FNTBD system consists of five steps:

1. Divide the input space into fuzzy regions.
2. Generate fuzzy rules from given data pairs through experimentation.
3. Avoid conflicting rules based on top-down or bottom-up methodologies.
4. Develop a combined fuzzy rule base.
5. Determine a mapping system based on the fuzzy rule base.

Learning is accomplished by fine-tuning the parameters in the fuzzy-nets system within the on-line learning capability. Following establishment of the rule base, the performance of the FNTBD system is examined for an end-milling operation. It was observed and verified experimentally that this new FNTBD approach can successfully detect tool breakage in end-milling operations.     

ADAPTIVE FEED-FORWARD COMPENSATOR FOR HARMONIC CANCELLATION IN ELECTRO- HYDRAULIC SERVO SYSTEM

Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic distortion of the output signal. The method for harmonic cancellation based on adaptive filter is proposed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion （THD） is greatly reduced. The weights of filter are adjusted on-line according to the control error by using least-mean-square （LMS） algorithm. Simulation results performed with a hydraulic system demonstrate the efficiency and validity of the proposed adaptive feed-forward compensator （AFC） control scheme     

输电网络规划与建设若干关键问题的研究

该文提出了一种自适应蚁群算法,对蚂蚁的状态转移策略进行改进,采用新的信息素更新规则并将路径上的信息素浓度限制在一个动态区间内,自适应地调整信息素强度Q和挥发因子ρ,有效地提高了蚁群算法全局寻优能力和收敛到最优解的速度。通过对Garver-6节点和IEEE-18节点系统的测试,结果表明了该方法的有效性。另外,为解决电网建设问题中高压输电铁塔塔上作业困难的问题,在深入调研了±800 k V特高压云广直流线路输电铁塔相关带电作业现状的基础上,设计了耐张塔专用多功能伸缩硬梯结构并进行了伸缩硬梯样品试制、实验测试以及现场试用。     

基于小波神经网络的切削刀具状态监测

提出了一种基于小波神经网络的切削刀具状态监测方法，即提取反映刀具磨损状态的特征参数，利用小波神经网络的非线性模型，实现在线状态监测；同时针对多输入输出问题带来的网络规模大、收敛速度慢等问题，提出了一种网络优化算法，即采用改进的遗传算法寻找最优小波基元，从而简化小波网络并加快收敛。仿真实例证明该方法是有效的。     

Recursive subspace identification for on-line tracking of structural modal parameter

The objective of this paper is to develop an on-line tracking of system parameter estimation and damage detection techniques using response measurements. To avoid the singular-value-decomposition in data Hankel matrix, a new subspace identification algorithm was developed. Seismic response data of a 3-story steel frame with abrupt change of inter-story stiffness from the shaking table test was used to verify the proposed recursive subspace identification (RSI) method by using both input and output measurements. With the implementation of forgetting factor in RSI method the ability of on-line damage detection of the abrupt change of structural stiffness can be enhanced. Then, the recursive stochastic subspace identification (RSSI) algorithm is also developed for continuous structural health monitor of structure by using the output-only measurements. Verification of the proposed RSSI method by using the white noise response data of a 2-story reinforced concrete frame from its low level white noise excitation was used. Discussion of the subspace identification model parameters is also investigated.     

基于规则进化模糊系统的步行方向意图识别

为了准确识别下肢功能障碍患者自主步行康复训练过程中的方向意图,提出了一种能够兼顾使用者个体差异及安全状态的新型步行方向意图识别方法。首先论述了康复训练机器人结构及患者前臂对机器人支撑板的压力和步行方向意图的关系。为保证患者安全地向任意方向行走,提出根据膝盖旋转角度推理安全步态的先决条件下,基于距离型模糊推理算法设计具有稀疏前件规则库的步行方向意图识别方法;然后为减小因个体差异、非稳定模糊规则引起的识别误差,提出规则进化算法实时优化模糊推理规则库。最后将该算法进行了多方向模糊推理实验与步行康复训练机器人压力控制实验,实验表明该算法可以准确识别下肢功能患者的任意步行方向意图并提高了步行的安全性,提出的步行方向意图识别方法可以应用在下肢功能障碍人士的日常起居与康复训练中。     

A modified NARMAX model-based self-tuner with fault tolerance for unknown nonlinear stochastic hybrid systems with an input–output direct feed-through term

A modified nonlinear autoregressive moving average with exogenous inputs (NARMAX) model-based state-space self-tuner with fault tolerance is proposed in this paper for the unknown nonlinear stochastic hybrid system with a direct transmission matrix from input to output. Through the off-line observer/Kalman filter identification method, one has a good initial guess of modified NARMAX model to reduce the on-line system identification process time. Then, based on the modified NARMAX-based system identification, a corresponding adaptive digital control scheme is presented for the unknown continuous-time nonlinear system, with an input–output direct transmission term, which also has measurement and system noises and inaccessible system states. Besides, an effective state space self-turner with fault tolerance scheme is presented for the unknown multivariable stochastic system. A quantitative criterion is suggested by comparing the innovation process error estimated by the Kalman filter estimation algorithm, so that a weighting matrix resetting technique by adjusting and resetting the covariance matrices of parameter estimate obtained by the Kalman filter estimation algorithm is utilized to achieve the parameter estimation for faulty system recovery. Consequently, the proposed method can effectively cope with partially abrupt and/or gradual system faults and input failures by the fault detection.     

An enhanced estimation of distribution algorithm for solving hybrid flow-shop scheduling problem with identical parallel machines

In this paper, an enhanced estimation of distribution algorithm (EEDA) is proposed to solve the hybrid flow-shop scheduling problem with identical parallel machines to minimize makespan. To evaluate the individuals, some decoding rules including the improved permutation scheduling rule, the improved list scheduling rule and the backward scheduling rule are designed for the permutation-based encoding scheme, and then a hybrid decoding method is proposed. To describe the distribution of the solution space for the EEDA, a probability model is built and used to generate new individuals by sampling. To well trace the region with promising solutions, a mechanism is provided to update the model with the superior sub-population. To enhance the exploitation capability, multiple local search operators are incorporated in the framework of the EEDA. The influence of the parameter setting is investigated based on the Taguchi method of design-of-experiment. Extensive numerical testing results based on sets of the well-known benchmarks and the comparisons with some existing algorithms demonstrate the effectiveness of the proposed algorithm.     

遮挡环境下采用在线Boosting的目标跟踪

针对被跟踪目标在发生严重遮挡时采用基于自学习方法的在线Boosting算法易导致错误累积而产生“漂移”甚至目标丢失的问题,提出了一种基于子区域分类器的在线Boosting算法.首先,将特征池划分为多个子区域分类器对应的子区域特征池;然后,在跟踪过程中自适应地选取子区域分类器来组成强分类器以剔除被遮挡子区域对目标定位的影响;最后,采用对子区域特征池进行部分更新的方法有效解决了特征在线更新时的错误累积问题.对不同视频序列测试的结果表明,当目标大面积被遮挡时本算法能准确定位目标,目标大小为36 pixel×40 pixel时的处理帧率为15 frame/s.与传统在线Boosting算法相比,本算法对发生严重遮挡的目标仍能进行准确跟踪.