Unbiased estimates for on-line system identification

An algorithm is derived for the determination of several unbiased estimates of the parameter vector of a discrete-time system, even in the presence of considerable noise, and requiring only one matrix inversion. From these noisy estimates an improved estimate can then be used by using stochastic approximation.     

单参数统一混沌系统的自适应控制同步

研究了单参数统一混沌系统的同步问题,提出了参数自适应控制同步方法;通过构造适当的控制函数和设计参数的自适应控制律,实现了两个不同参数的统一混沌系统的同步;根据Lyapunov稳定性定理,导出了两不同参数混沌系统能实现同步的充分条件,无论驱动系统处于何种状态,该方法都可使响应系统按照驱动系统给定的轨道演化。数值仿真表明了该方法的有效性。     

Adaptive algorithms for sparse system identification

In this paper, identification of sparse linear and nonlinear systems is considered via compressive sensing methods. Efficient algorithms are developed based on Kalman filtering and Expectation-Maximization. The proposed algorithms are applied to linear and nonlinear channels which are represented by sparse Volterra models and incorporate the effect of power amplifiers. Simulation studies confirm significant performance gains in comparison to conventional non-sparse methods.     

Continuous-time system identification on compact parameter sets

The problem of consistent estimation of the unknown parameters of linear time-invariant continuous-time systems is considered. The unknown parameter set is assumed to be compact, and only noisy observations of the system output are available. Sufficient conditions are derived for global strong consistency of the maximum-likelihood parameter estimates. The consistency proof exploits a recent result due to Delchamps concerning smoothness of the algebraic Riccati equation in the system parameters. This smoothness result has been tacitly assumed in the literature on local consistency of the parameter estimates. The previous global consistency results have been obtained under the restrictive assumption of finite parameter sets.     

参数未知时滞混沌系统的自适应同步

考虑参数不确定的多维时滞混沌系统作为驱动系统(发射系统),系统的未知参数能够在系统中线性表示.采用参数辨识与自适应技术,在响应系统(接收系统)中应用线性反馈与参数自适应控制,使得驱动系统与响应系统能够混沌同步,并且响应系统的参数逐步逼近驱动系统的参数.利用Lyapunov泛函与最大不变集原理(Lassel)给出了理论分析与证明.理论分析与数值模拟结果表明该自适应控制同步策略的有效性.     

在线连续交互式英语语音智能识别系统设计

英语语音智能识别系统的发展方向是在线、连续性的人机交互,为此,设计在线连续交互式英语语音智能识别系统,并基于梅尔频率倒谱系数设计语音识别函数。系统的参考数据库选取NOSE算法计算语音评价分数并查错,利用专家知识库纠正用户英语语音。系统由语音训练模块和在线连续交互式识别模块组成,前者为系统数据库提供英语语音的语料、音标资源,后者实施系统数据库的评价、纠正工作。实验结果证明设计的系统语音识别率高且识别时间短,有效性强。     

时滞时变对象参数辨识方法

针对时滞时变系统,提出了一种参数辨识的新方法.该算法一方面采用互相关函数来辨识滞后时间,并引进了快速傅里叶变换及其反变换,提高了计算效率;另一方面,在变参数增量估计递推最小二乘算法估计时变参数的基础上,引入误差级序列,改善了时变参数的辨识精度.最后通过仿真验证了该方法的良好性能.     

Intelligent quality controllers for on-line parameter design

Parameter design methods, in general, do not take into account the common occurrence that some of the uncontrollable factors are observable for products and processes, during operation and production, respectively. This paper introduces a methodology that facilitates on-line parameter design for products and processes utilizing the extra information available about observable uncontrollable factors. Implementation of the proposed methodology leads to a quality controller that operates in two distinct modes: identification mode and on-line parameter design mode, identification mode involves establishing a model that relates quality response characteristics with significant controllable and uncontrollable variables. On-line parameter design mode involves optimization of the controllable variables with respect to desired levels of output quality parameters, with consideration to levels of the observable uncontrollable variables. A plasma etching semiconductor manufacturing process is used as a testbed for the proposed intelligent quality controllers. Results reveal that the proposed quality controllers can be used for on-line parameter design of manufacturing processes. Results also reveal that significant improvements in quality (measured in terms of average deviation of process outputs from target) over off-line parameter design approaches are to be expected in production processes with some level of control on uncontrollable variables. Even in the absence of any control on uncontrollable variables, the proposed controllers always perform better than traditional off-line robust parameter design techniques; however, the improvements may not be significant     

基于自适应同步的混沌系统参数辨识方法的研究

利用混沌系统的动力学特性对参数极其敏感的特点,以驱动响应同步结构为框架,设计了与同步误差有关的二次型指标函数,采用优化方法对参数进行自适应调节,直到同步误差最小,即实现混沌同步.该方法实现了参数未知混沌系统的参数辨识和自适应同步.为了研究参数收敛速度,对准高斯牛顿法、Hook-Jeeves方法(又名模式搜索法)和共轭梯度法等三种优化方法进行了对比研究.对具有两个未知参数的离散Hénon系统和连续Lorenz系统的仿真研究表明,基于共轭梯度的参数调节方法参数收敛速度最快,可以应用于混沌保密通信的解密.     

Sensorless control of permanent-magnet synchronous motors using online parameter identification based on system identification theory

An online parameter identification method and sensorless control using identified parameters were realized in surface and interior permanent-magnet synchronous motors (SPMSMs and IPMSMs, respectively). As this method does not use rotor position or velocity to identify motor parameters, the identified parameters are not affected by position estimation error under sensorless control. The proposed method can be applied to all kinds of synchronous motors. The effectiveness of the proposed method was verified by experiments in both SPMSMs and IPMSMs.     

An on-line least-squares parameter estimator with finiteconvergence time

An online parameter-estimation algorithm is presented which has the following features: (1) it reduces to the linear least-squares (LS) estimator after a set of regression vectors that span the full dimension of the parameter space has been processed, and (2) when the regression model is linear in the parameters, the parameter and prediction errors converge to zero in finite time. Both continuous- and discrete-time versions of the algorithm are given     

Adaptive log domain filters for system identification using floating gate transistors

We describe an adaptive log domain filter with integrated learning rules for model reference estimation. The system is a first-order low pass filter implemented using multiple input floating gate transistors operating in subthreshold to realize on-line learning of gain and cut-off frequency. We use adaptive dynamical system theory to derive robust control laws for gain and cut-off frequency adaptation in a system identification task. Simulation results show that convergence is slower using simplified control laws but still occurs within milliseconds. Experimental results confirm that the estimated gain and cut-off frequency track the parameters of the reference filter. The adaptive log domain filter has measured power consumption of 33 μW. During operation, deterministic errors are introduced by mismatch within the analog circuit implementation. An analysis is presented which attributes the errors to current mirror mismatch.     

在线考试系统的设计

文中系统为基于Java的在线考试系统。用户由学生、教师和系统管理员组成。学生登录系统可以进行在线测试和成绩查询。后台管理员可以对考题、考试设置信息、用户信息进行维护。学生、教师、管理员都可以对个人信息进行维护。将传统形式的考试电子化,基本上实现了传统意义上考试的所有功能流程。     

Thermal parameter estimation using recursive identification

A novel method that converts a semiconductor transient thermal impedance curve (TTIC) into an equivalent thermal RC network model is presented. Thermal resistance (R) and thermal capacitance (C) parameters of the model are identified using manufacturer's data and offline recursive least square techniques. Relevant estimation theory concepts and the formulation of an appropriate model for the identification process are given. Model synthesis is illustrated using an isolated base power transistor module. The application of time decoupled theory for high order thermal models is outlined. Simulation of junction temperature responses using model and manufacturer TTICs are compared. Estimated parameter validity is further confirmed by parameter calculation obtained from module physical dimensions     

Modeling, control, and validation of an electro-hydraulic steer-by-wire system for articulated vehicle applications

X-by-wire control systems in automotive applications refer to systems where the input device used by the operator is connected to the actuation power subsystem by electrical wires, as opposed to being connected by mechanical or hydraulic means. The "X" in the X-by-wire is replaced by "steer", "throttle", and "brake" to represent the steer-by-wire, throttle-by-wire, and brake-by-wire systems. Common to all of these subsystems is that the operator control input device (i.e., steering column, acceleration pedal, and brake pedal) is not connected to the actuation devices mechanically. Rather, it is connected to an embedded computer which, in turn, sends the control signals to the actuation devices. Current state of art steering systems used in articulated vehicles are hydro-mechanical type systems, i.e., the steering column motion is transmitted and amplified by the main hydraulic circuit by hydro-mechanical means. This paper presents a new steer-by-wire (SBW) system which we designed, modeled, analyzed, and tested on wheel type loader construction equipment. The simulation results and tests conducted on a prototype development vehicle (a medium size wheel type loader) show very good agreement. The control algorithm is modeled using graphical modeling tools similar to Simulink and StateFlow. A real-time control algorithm is implemented on a Motorola 68332 microprocessor-based embedded controller. The operational performance of the steer-by-wire system has been convincingly demonstrated.     

无线场景自动识别及参数配置

无线场景是指具有某种属性的小区类别,本文将小区的网内场景按照地貌、话务,站距、覆盖等属性进行了划分,按照TD/GSM的重选和切换关系划分了网间场景,研究了小区无线场景的自动识别技术,并对场景与参数之间的关系进行了探讨.