工业过程多速率分层运行优化控制

工业过程运行优化控制通常采用基础回路层和运行层两层结构,涉及不同时间尺度特性的被控对象,且由于检测装置采样周期不同难以统一控制与采样周期;此外,运行层动态往往机理复杂难以建模.因此针对这一多层次、多时间尺度且部分模型未知的复杂多速率控制问题,本文提出一种工业过程多速率分层运行优化控制方法.该方法在使用提升技术解决分层多速率问题的基础上,采用一种基于Q-!学习的数据驱动运行层设定值优化方法,更新基础回路层的设定值;并针对提升后的系统采用模型预测控制（Model predictive control,MPC）方法设计基础回路层控制器以跟踪设定值,从而实现运行指标的优化控制.对典型工业闭路磨矿过程进行了仿真实验,验证了本文所提方法的有效性.     

基于连续控制集的永磁同步直线电机模型预测控制

永磁同步直线电机(permanent magnet linear synchronous motor, PMLSM)目前多被应用于直线牵引系统,例如轨道交通、无绳电梯等.传统的永磁同步直线电机预测控制主要考虑有限控制集模型预测控制(finite-control-set model predictive control, FCS–MPC),在一个系统采样周期从备选的开关状态中选择一个相对最优的开关状态送入逆变器中.该方法的计算量通常随着预测步长的增加呈几何增长,因而限制了其广泛使用.本文针对PMLSM提出一种基于二次优化的连续控制集模型预测控制(continuous-control-set model predictive control, CCS–MPC)策略.该方法在每个周期内选择两组开关状态送入逆变器,表现为两个相邻电压矢量的合成,因而可以达到更为平滑的控制效果.策略结合了FCS–MPC中的扇区划分原理,将扇区中的两个相邻非零矢量和一个零矢量等效合成为二次优化的最优控制矢量.与此同时,在二次优化的框架下CCS–MPC有效地避免了多步预测控制中计算量过大的问题.仿真与实验结果表明在相同条件下,所提方法相较于空间矢量调制以及FCS–MPC能获得更好的PMLSM控制效果.     

工业大系统双层结构预测控制的集中优化与分散控制策略

为降低工业大系统模型预测控制(Model predictive control,MPC)在线计算复杂度,同时保证系统的全局优化性能,提出一种集中优化、分散控制的双层结构预测控制策略.在稳态目标计算层(Steady-state target calculation, SSTC),基于全局过程模型对系统进行集中优化,将优化结果作为设定值传递给动态控制层;在动态控制层,将大系统划分为若干个子系统,每个子系统分别由基于各自子过程模型的模型预测控制进行控制,为减少各子系统之间的相互干扰,在各个子系统之间添加前馈控制器对扰动进行补偿,提高系统的总体动态控制性能.该策略的优点在于能确保系统全局最优性的同时降低了在线计算量,提高了工业大系统双层结构预测控制方法的实时性.仿真实例验证该方法的有效性.     

面向自由飞行目标捕获的四旋翼最优轨迹规划

自由飞行目标物捕获作为动态任务，在其被执行的过程中，四旋翼不仅要规划出一条时间最优的追踪轨迹，而且还要根据目标物的位置反馈信息实时对轨迹进行重新规划，以实现在最短的时间内追上目标物.针对这一问题，提出了诱导时间最优MPC （model predictive control）算法用于四旋翼的轨迹规划.该算法通过宽松约束条件下时间最优轨迹的引导，利用MPC的滚动优化策略，可以在每个控制周期内用反馈信息实时求解时间最优的追踪轨迹.为了躲避追踪路径中的障碍物，本文还提出了一种用动态线性约束表示障碍物的方法，以提高障碍物约束下轨迹求解的效率.结合诱导时间最优MPC的算法，可以在线实时地求解出具有障碍物避碰能力的时间最优轨迹.仿真结果表明了本文提出算法的有效性，其高效的计算效率也能满足实际系统对算法实时性的要求.     

小型无人直升机的模型预测控制算法研究

针对无人直升机在阵风干扰环境中的姿态控制精度低的问题.本文将非线性刚体动力学模型在悬停点应用小扰动理论得到了线性化数学模型.考虑系统输入输出和控制量约束,采用模型预测控制将控制器的设计问题转化为每个采样时刻求解一个带不等式和等式约束的凸二次规划问题.通过设计终端状态约束解决了有限时域模型预测控制(model predictive control, MPC)算法的稳定性问题,并通过引入松弛变量使得约束优化问题更容易求解.随机和常值阵风干扰下无人机悬停仿真验证了本文MPC预测控制器具有幅度不超过0.25 m/s的良好干扰抑制能力,性能明显优于线性二次型调节器(linear-quadratic regulator, LQR).     

移动威胁情况下的无人机路径规划

针对路径规划中存在快速移动威胁, 提出基于威胁状态预测的模型预测控制(MPC)算法, 进行无人机动态路径规划. 采用转换量测卡尔曼滤波算法预测移动威胁的状态, 弥补MPC算法无法有效预测快速移动威胁的不足. 根据移动威胁的预测状态, 评估无人机的威胁代价, 与路径长度等约束共同构建目标函数, 通过滚动优化目标函数, 得到一系列在线控制量, 完成路径规划. 仿真结果表明该方法可以有效躲避移动威胁, 进行实时路径规划.     

一种新的基于PSO的MPC及其硬件实现

模型预测控制(MPC)在流程工业中应用已经比较成熟.其核心为在线求解二次规划(QP)问题,运算负荷大时延长,对控制器的运算能力要求高,阻碍了MPC向更深更广的应用领域拓展.为解决上述问题,从算法本身和硬件平台2个方面入手,提出了MPC算法一种新的实现方案.新的以粒子群优化算法(PSO)为核心的MPC算法很好地解决了带约束的二次规划问题,并且以可编程逻辑门阵列(FPGA)为平台用实现了PSO-MPC控制器.这一方案使得MPC可以应用在控制器体积受限,采样频率高的运动控制场合.     

多速率预测控制系统最优采样周期的研究

随着社会工业的不断发展,在复杂的化工过程中越来越多地开始采用多速率控制系统,而采样周期是这种数字控制系统中的重要参数,对系统有着多方面的影响。目前基于采样周期的选取大多数是根据传统的实际经验来确定选取范围,还没有1种方法能够较准确的找到系统所需求的最适合的采样周期。本文针对一类多输入——多输出的系统,采用动态矩阵预测控制算法,通过建立1个简单的两输入——两输出系统的输入多速率模型,进一步推导出了多输入——多输出系统基于动态矩阵的通用输入多速率模型;采用经典的优化算法——遗传算法,对这种输入多速率下采样周期进行了优化选取,并针对一类双入双出的快慢耦合系统进行了仿真,在基本采样周期T一定的条件下,找到了使得系统控制性能最优的各个输入采样周期,得到最优控制效果(积分平方误差),对应的两个输入采样周期分别为基本采样周期的5倍和1倍,并将其与单速率下的控制性能进行了比较。结果表明,本文提出的这种方法可以有效的得到系统最优的采样周期,并且,对于这种病态耦合系统,在采样周期的适当选取下,输入多速率下系统的稳定性及综合控制性能优于单速率控制系统。     

高速列车精确停车的鲁棒自触发预测控制

列车精确停车作为列车自动运行(Automatic train operation, ATO)系统的一项核心功能, 对高速列车的安全和高效运行至关重要. 本文针对高速列车停车过程的特点, 考虑在避免控制输出频繁切换的前提下实现高精度的停车曲线跟踪, 提出了基于模型预测控制(Model predictive control, MPC)的精确停车算法. 针对列车停车过程中外部不确定性阻力干扰, 采用鲁棒模型预测控制方法, 提高对外部干扰的鲁棒性. 引入自触发控制策略, 以进一步减少控制输出的频繁切换, 提高停车过程的舒适度. 该方法不需要每个采样时间都求解线性约束二次规划问题, 降低了对系统采样和通信能力的要求, 提高了算法的实用性. 分析结果表明, 高速列车精确停车控制方法的稳定性和性能指标的次优性可以得到保证. 基于高速列车实际运行数据的仿真结果验证了算法的有效性.     

多速率分段线性系统预测控制的显式设计

针对输出采样周期是输入更新周期N倍的多速率分段线性(Piecewise linear, PWL)系统, 本文提出了保证稳定性的显式预测控制器设计方法. 首先, 基于动态规划原理将预测控制优化问题分解为多个单级优化问题; 然后, 根据分段线性系统各子模型以及目标函数的具体形式, 进一步将各单级优化问题分为若干个子问题, 再利用多参数二次规划(Multiparametric quadratic programming, MP-QP)方法求解;最后,通过比较各子问题的解从而得到系统的最优显式控制律. 在设计过程中, 将系统的最大正不变集作为优化问题的终端约束集, 从而保证了系统的稳定性. 仿真结果表明本文提出的显式预测控制方法能够有效降低多速率分段线性系统的在线计算时间, 在保证系统稳定性的同时, 满足其对输入更新速度的要求.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.