共查询到20条相似文献,搜索用时 31 毫秒
1.
Paulo Rosa Jeff S. Shamma Carlos Silvestre Michael AthansAuthor vitae 《Automatica》2011,(5):1007-1014
This paper proposes an architecture referred to as Stability Overlay (SO) for adaptive control of a class of nonlinear time-varying plants. The SO can be implemented in parallel with a wide range of “performance-based” adaptive control laws, i.e., adaptive control laws that seek to improve closed-loop performance, but may be susceptible to instability in the presence of unaccounted model uncertainty. In this architecture, the performance-based adaptive control law designates candidate controllers based on performance considerations, while the SO supervises this selection based upon online robust stability considerations. A particular selection of a performance-based adaptive control law is not specified. Rather, this selection can be from a wide range of adaptive control schemes. This paper provides stability proofs for the SO architecture and presents a simulation that illustrates the applicability of the proposed method. 相似文献
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Adaptive system often refers to the adaptive control system. In this paper, we discuss the adaptive system concept from an architectural perspective of the system. We use the robotic system as an example to illustrate the adaptive system concept, because the robotic system is a generic system underlying many manufacturing systems. Specifically, the paper presents our work on the development of a general architecture of the adaptive robotic system for manufacturing applications. The contribution of this paper includes: (i) elaboration of the concept of adaptive system and classification of means to make the system adaptive and (ii) formulation of a general architecture of the adaptive robotic system based on the criterion that the more system variants out of the architecture implies the more generality of the architecture. Throughout this paper, we use an industrial robotic system for illustration. 相似文献
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Feedback Control Architecture and Design Methodology for Service Delay Guarantees in Web Servers 总被引:1,自引:0,他引:1
Chenyang Lu Ying Lu Abdelzaher T.F. Stankovic J.A. Sang Hyuk Son 《Parallel and Distributed Systems, IEEE Transactions on》2006,17(9):1014-1027
This paper presents the design and implementation of an adaptive Web server architecture to provide relative and absolute connection delay guarantees for different service classes. The first contribution of this paper is an adaptive architecture based on feedback control loops that enforce desired connection delays via dynamic connection scheduling and process reallocation. The second contribution is the use of control theoretic techniques to model and design the feedback loops with desired dynamic performance. In contrast to heuristics-based approaches that rely on laborious hand-tuning and testing iteration, the control theoretic approach enables systematic design of an adaptive Web server with established analytical methods. The adaptive architecture has been implemented by modifying an Apache server. Experimental results demonstrate that the adaptive server provides robust delay guarantees even when workload varies significantly. 相似文献
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提出了基于免疫体系的安全数据库四层结构:身份认证层,存取控制层,约束安全层,适应性检测层。并给出了约束安全层和适应性检测层的予层结构。将约束安全层分为完整性约束、分级和推理约束、访问约束和应用语义约束四个予层,将适应性检测层分为数据库活动级、关系模式级、事务级和应用语义级四个子层。构造了一个多层多级的数据库安全体系,最后给出了具体实现方案。 相似文献
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自适应笔式用户界面开发的概念框架 总被引:1,自引:0,他引:1
提出了一个指导自适应笔式用户界面开发的概念框架CFAPUI(a conceptual framework for developing adaptive pen-based user interface).该框架详细描述了自适应笔式用户界面的软件体系结构,阐述了自适应笔式用户界面的软件体系结构中的各组成模块及其相互间的关系.同时,在体系结构的基础上提出自适应笔式用户界面开发时的具体过程步骤和方法,并通过一个笔式表单应用来说明该开发框架在指导自适应笔式用户界面开发中的具体应用. 相似文献
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del Campo I. Echanobe J. Bosque G. Tarela J.M. 《Fuzzy Systems, IEEE Transactions on》2008,16(3):761-778
This paper describes the development of efficient hardware/software (HW/SW) neuro-fuzzy systems. The model used in this work consists of an adaptive neuro-fuzzy inference system modified for efficient HW/SW implementation. The design of two different on-chip approaches are presented: a high-performance parallel architecture for offline training and a pipelined architecture suitable for online parameter adaptation. Details of important aspects concerning the design of HW/SW solutions are given. The proposed architectures have been implemented using a system-on-a-programmable-chip. The device contains an embedded-processor core and a large field programmable gate array (FPGA). The processor provides flexibility and high precision to implement the learning algorithms, while the FPGA allows the development of high-speed inference architectures for real-time embedded applications. 相似文献
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Asif Qumer Gill Brian Henderson-Sellers Mahmood Niazi 《Information Systems Frontiers》2018,20(2):315-341
The adoption of agility at a large scale often requires the integration of agile and non-agile development elements for architecting a hybrid adaptive methodology. The challenge is ”which elements or components (agile or non-agile) are relevant to develop the context-aware hybrid adaptive methodology reference architecture?” This paper addresses this important challenge and develops a hybrid adaptive methodology reference architecture model using a qualitative constructive empirical research approach. In this way, we have uncovered the agility, abstraction, business value, business policy, rules, legal, context and facility elements or components that have not been explicitly modelled or discussed in International Standards (IS) such as the ISO/IEC 24744 metamodel. It is anticipated that a context-aware hybrid adaptive methodology can be architected by using the proposed context-aware hybrid adaptive methodology reference architecture elements for a particular situation when using a situational method engineering approach. 相似文献
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提出一种新型的网络结构-反图对角网格,分析反图对角网格网络的优点,在这种新型网络结构上提出了一种可容错的自适应路由算法,无故障情况下消息通过无死锁确定性路由进行寻径,有故障情况下消息通过自适应路由沿着故障块进行寻径。 相似文献
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针对运行于开放、不确定环境下的SOA架构的多使命复杂关键型系统,提出了一种以混合关键度为驱动的动态分级自适应资源分配算法。它通过构造闭环反馈的分布式控制环,在线动态调整任务Qos,针对不同关键度的任务动态调整资源分配。该方法不但在统计意义上确保了关键型系统的实时性,而且实验证明该方法能有效提高系统在高负载条件下的实际资源利用率和降低关键任务的死线错过率,保证了关键型系统的高可靠性。 相似文献
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在当前的自适应软件研究中,人们将更多的关注点放在环境感知、服务质量建模、编程语言等方面,从而导致缺乏对自适应过程和原理的深入揭示的问题.关注体系结构,研究动态自适应过程,提出了一种软件体系结构重配置方法.该方法通过对构件、连接子的添加、删除和替换等操作来调整体系结构.基于云计算的服务器池大小动态自适应调整实验表明,动态自适应能提高系统的可信度,降低运行费用. 相似文献
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同步策略是并行离散事件模拟的关键技术之一。POSE是一种面向对象的可扩展的计算机体系结构并行模拟框架,可进行大规模系统的并行模拟。剖析了POSE框架中的乐观同步策略,按照时间窗口调整状况将其自适应策略分为半自适应策略和完全自适应策略;对自适应乐观同步策略的模拟速度与精度进行了深入的测试比较,发现经过调整半自适应乐观策略能够取得更好的性能;也发现现有完全自适应算法中存在窗口调节反馈滞后和GVT计算开销过大等问题,是其乐观策略优化的方向之一。 相似文献
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K. Merve Dogan Benjamin C. Gruenwald Jonathan A. Muse 《International journal of control》2018,91(8):1774-1784
It is known that a closed-loop dynamical system subject to an adaptive controller remains stable either if there does not exist significant unmodelled dynamics or the effect of system uncertainties is negligible. This implies that these controllers cannot tolerate large system uncertainties even when the unmodelled dynamics satisfy a set of conditions. In this paper, we present an adaptive control architecture such that the proposed adaptive controller is augmented with an adaptive robustifying term. Unlike standard adaptive controllers, the proposed architecture allows the closed-loop dynamical system to remain stable in the presence of large system uncertainties when the unmodelled system dynamics satisfy a set of conditions. A numerical example is provided to demonstrate the efficacy of the proposed approach. 相似文献
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Since the early 1980's, intelligent and adaptive systems have appeared and have been written about in a variety of guises. Although there are many differences between such systems as adaptive user interfaces, intelligent help systems and explanation systems, there are many similarities as well. The most notable of these is that they all require user models to be maintained and exploited as part of their designs. Furthermore, they share the same high level architecture. This paper discusses the use of models in human-computer interaction design and offers a common architecture for these adaptive systems. A methodology for the development of these systems is presented.This is based on our experimental work which is reported fully in Jennings, Benyon and Murray, 1991 and Jennings and Benyon, in press) 相似文献
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This paper suggests a new fuzzy adaptive controller, which is able to solve the problems of classical adaptive controllers and conventional fuzzy adaptive controllers. It explains the architecture of a fuzzy adaptive controller using the robust property of a fuzzy controller. The basic idea of new adaptive control scheme is that an adaptive controller can be constructed with parallel combination of robust controllers. This new adaptive controller uses a multirule-base architecture which has several independent fuzzy controllers in parallel, each with different robust stability area. Out of several independent fuzzy controllers, the most suited one is selected by a system identifier which observes variations in the controlled system parameter. Here, we propose a design procedure which can be carried out mathematically and systematically from the model of a controlled system; related mathematical theorems and their proofs are also given. The performance of the proposed adaptive control algorithm is analyzed through a design example and a DC motor control simulation 相似文献
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This paper illustrates the application of an adaptive flight control architecture to a scale quad-rotor. For autonomous vertical takeoff and landing flight, it is common to separate the control problem into an inner fast loop that controls attitude and an outer slow loop that controls the trajectory tracking. In this paper, we augment a conventional proportional and derivative controller conceived mainly for hovering, with an adaptive element using a real-time tuning single hidden layer neural network in a inner–outer loop combined architecture to account for model inversion error cancelation, issued in the feedback linearization process. The results shown in simulations reveal the superior performance of the augmented controller in tracking maneuvers. 相似文献
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The objective of this paper is to present a cognitive architecture thatutilizes three different methodologies for adaptive, robust control ofrobots behaving intelligently in a team. The robots interact within a worldof objects, and obstacles, performing tasks robustly, while improving theirperformance through learning. The adaptive control of the robots has beenachieved by a novel control system. The Tropism-based cognitive architecturefor the individual behavior of robots in a colony is demonstrated throughexperimental investigation of the robot colony. This architecture is basedon representation of the likes and dislikes of the robots. It is shown thatthe novel architecture is not only robust, but also provides the robots withintelligent adaptive behavior. This objective is achieved by utilization ofthree different techniques of neural networks, machine learning, and geneticalgorithms. Each of these methodologies are applied to the tropismarchitecture, resulting in improvements in the task performance of the robotteam, demonstrating the adaptability and robustness of the proposed controlsystem. 相似文献
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This paper presents an adaptive control scheme with an integration of sliding mode control into the $\mathcal{L}_1$ adaptive control architecture, which provides good tracking performance as well as robustness against matched uncertainties. Sliding mode control is used as an adaptive law in the $\mathcal{L}_1$ adaptive control architecture, which is considered as a virtual control of error dynamics between estimated states and real states. Low-pass filtering mechanism in the control law design prevents a discontinuous signal in the adaptive law from appearing in actual control signal while maintaining control accuracy. By using sliding mode control as a virtual control of error dynamics and introducing the low-pass filtered control signal, the chattering effect is eliminated. The performance bounds between the close-loop adaptive system and the closed-loop reference system are characterized in this paper. Numerical simulation is provided to demonstrate the performance of the presented adaptive control scheme. 相似文献