Problems with expert systems in real-time control

There is increasing use of knowledge-based or expert systems in the process and manufacturing industries, with currently in excess of 2000 installations. The advantage offered by such systems is their ability to deal with complex and possibly incorrect or incomplete data. A new generation of expert-system tools, designed specifically for real-time control applications, has been developed. This paper examines the requirements of an expert system for real-time control, and shows how current approaches attempt to meet them. It is argued that none of the currently available tools fully satisfy the needs of a real-time expert control system, particularly in terms of reliability and guaranteed real-time response.     

Real-time smart video surveillance to manage safety: A case study of a transport mega-project

There is a tendency for accidents and even fatalities to arise when people enter hazardous work areas during the construction of projects in urban areas. A limited amount of research has been devoted to developing vision-based proximity warning systems that can determine when people enter a hazardous area automatically. Such systems, however, are unable to identify specific hazards and the status of a piece of plant (e.g., excavator) in real-time. In this paper, we address this limitation and develop a real-time smart video surveillance system that can detect people and the status of plant (i.e. moving or stationary) in a hazardous area. The application of this approach is demonstrated during the construction of a mega-project, the Wuhan Rail Transit System in China. We reveal that our combination of computer vision and deep learning can accurately recognize people in a hazardous work area in real-time during the construction of transport projects. Our developed systems can provide instant feedback concerning unsafe behavior and thus enable appropriate actions to be put in place to prevent their re-occurrence.     

A simple approximation to rigid body dynamics for computer animation

Recently, the dynamics of linked articulated rigid bodies has become a valuable tool for making realistic three-dimensional computer animations. An exact treatment of rigid body dynamics, however, is based on rather non-intuitive results from classical mechanics (e.g. the Euler equations for rotating bodies) and it relies heavily on sophisticated numerical schemes to solve (large) sets of coupled non-linear algebraic and differential equations. As a result, articulated rigid bodies are not yet supported by most real-time animation systems. This paper discusses an approach to rigid body dynamics which is based on (both conceptually and algorithmically much simpler) point mechanics; this gives rise to an asymptotically exact numerical scheme (NSI) which is useful in the context of real-time animation, provided that the number of degrees of freedom of the simulated system is not too large. Based on NSI, a second scheme (NS2) is derived which is useful for approximating the motions of linked articulated rigid bodies; NS2 turns out to be sufficiently fast to give at least qualitative results in real-time simulation. In general, the algorithm NS2 is not necessarily (asymptotically) exact, but a quantitative analysis shows that in the absence of reaction forces it conserves angular momentum.     

一种基于计算机取证的信息一致性方案

计算机数据自身的脆弱性,使计算机取证信息的一致性问题成为计算机证据鉴定过程中的关键所在。该文在计算机取证的基础上,运用DSA签名机制,提出了一种证明计算机证据完整性的一致性方案。该方案能够在计算机系统运行过程中,实时、安全地转移所获取的取证信息,并进行证据固定,以保证其完整性。在基于某些密码学假设的前提下,证明了方案的安全性。     

适用于实时协同编著系统的并发控制研究

实时协同编著系统是最受欢迎的实时ＣＳＣＷ应用系统之一，适用于实时协同编著系统的并发控制用于解决参与协同工作用户对共享对象操作时存在的冲突问题。本文对这种新的并发控制与适用于分布式数据库系统等的传统并发控制进行了比较，讨论了一些适用于实时协同编著系统并发控制方法的新评价参数，分析了传统并发控制方法应用到实时协同编著系统时所遇到的问题。最后，我们介绍了一些文献中已有原型系统所使用的并发控制方法。     

The challenges of real-time AI

The research agendas of artificial intelligence and real-time systems are converging as AI methods move toward domains that require real-time responses, and real-time systems move toward complex applications that require intelligent behavior. They meet at the crossroads in an exciting new subfield commonly called “real-time AI.” This subfield is still being defined, and the precise goals for various real-time AI systems are in flux. Our goal is to identify promising areas for future research in both real-time and AI techniques. We describe an organizing conceptual structure for current real-time AI research, exploring the meanings this term has acquired. We then identify the goals of real-time AI research and specify some necessary steps for reaching them     

Developing highly reliable software

To build dependable software for safety-related applications in nuclear power plants, we developed a few qualified software components and used them in all the systems. Most of the safety-critical systems are real-time systems that require a guaranteed response time. These systems need real-time supervisory software to control task execution according to well-defined priority requirements. This led us to develop a highly reliable real-time executive called X-RTE     

移动机器人运动规划与计算机控制实现

论文针对移动机器人的链式系统提出了一种实时运动规划方法,通过在线更新复合分段常值与多项式输入控制律的系数,来驱使系统到达预定的目标,并将其应用于两伺服直流电机独立控制轮式移动机器人,采用计算机系统以及伺服放大器实现其控制,控制的结果达到了预期的效果。     

Explaining how to play real-time strategy games

Real-time strategy games share many aspects with real situations in domains such as battle planning, air traffic control, and emergency response team management which makes them appealing test-beds for Artificial Intelligence (AI) and machine learning. End-user annotations could help to provide supplemental information for learning algorithms, especially when training data is sparse. This paper presents a formative study to uncover how experienced users explain game play in real-time strategy games. We report the results of our analysis of explanations and discuss their characteristics that could support the design of systems for use by experienced real-time strategy game users in specifying or annotating strategy-oriented behavior.     

分布式实时系统任务与消息综合调度算法研究

分布式实时系统作为一种典型的实时系统应用受到了关注,目前提出了许多分布式实时系统的调度策略。但是,绝大多数策略往往忽略了全局任务调度时的消息调度。本文提出一种综合任务调度和消息调度的算法,提供了一种实时系统调度的新思路。     

面向运动控制的调度抖动问题的研究

通用处理器以其优异的性能已经越来越广泛地应用到实时控制系统中，但其所采用的体系结构会引起指令执行时间的不确定性，导致基于它的实时系统存在调度抖动问题,调度抖动是实时控制系统的重要性能指标之一，本文讨论了抖动测试和分析技术，并介绍了减少抖动的补偿技术．     

Decomposition of human motion into dynamics-based primitives with application to drawing tasks

Using tools from dynamical systems and systems identification, we develop a framework for the study of primitives for human motion, which we refer to as movemes. The objective is understanding human motion by decomposing it into a sequence of elementary building blocks that belong to a known alphabet of dynamical systems. We develop a segmentation and classification algorithm in order to reduce a complex activity into the sequence of movemes that have generated it. We test our ideas on data sampled from five human subjects who were drawing figures using a computer mouse. Our experiments show that we are able to distinguish between movemes and recognize them even when they take place in activities containing an unspecified number of movemes.     

An application of artificial intelligence to object-orientedperformance design for real-time systems

The paper describes an application of artificial intelligence technology to the implementation of a rapid prototyping method in object-oriented performance design (OOPD) for real-time systems. OOPD consists of two prototyping phases for real-time systems. Each of these phases consists of three steps: prototype construction, prototype execution, and prototype evaluation. We present artificial intelligence based methods and tools to be applied to the individual steps. In the prototype construction step, a rapid construction mechanism using reusable software components is implemented based on planning. In the prototype execution step, a hybrid inference mechanism is used to execute the constructed prototype described in declarative knowledge representation. MENDEL, which is a Prolog based concurrent object-oriented language, can be used as a prototype construction tool and a prototype execution tool. In the prototype evaluation step, an expert system which is based on qualitative reasoning is implemented to detect and diagnose bottlenecks and generate an improvement plan for them     

Linux操作系统的实时化分析

随着实时操作系统的广泛应用和Linux的迅速发展,人们更加关注实时Linux的开发问题。文中,我们讨论了调度策略、内核的可重入性、中断处理以及内存管理机制等关键问题。这些问题与Linux扩展到实时操作系统密切相关。然后,我们详细分析了两个有代表性的实时Linux,即RT Linux和KURT Linux的主要实现。我们还介绍了它们自己的特性以及它们之间的基本差异。最后提出了未来的研究工作。     

计算机建模实现路口交通流量实时监测技术探析

目前我国城市的交通控制多采用信号灯方式,人工设置时间,定时自动放行,这种方法,无法根据对各个路口实际交通流量变化进行实时监测与控制,因此,需要一种新型化的模式来对路口交通流量实时监测,计算机建模的应用,有利于设计优化管理模型,使得信号灯自动优化,实时监测,根据实际情况自动疏导拥堵,从而最大限度的改善交通拥挤等状况。     

High Accuracy Concurrent Event Processing in Hard Real-Time Systems

A computer organisation suitable to improve the performance of embedded systems encountered in hard real-time environments is described, which enhances dependability and efficiency by exploiting possibilities for parallel processing inherent to real-time systems. It is shown that internal data transmissions due to context-switching can be eliminated and that CPUs can be relieved from a considerable amount of routine work by providing a separate module for major functions of real-time operating systems, viz., for interrupt and signal recognition, for time management, and for the administration of task execution plans and states. Considering the layer model of contemporary real-time operating systems, these functions constitute kernel and first layer. The hardware implementation of typical hard real-time support features provides a clear physical separation of the intrinsically independent functions event reaction and (user) task processing. While minimising response times in general, the architecture enables to guarantee predefined, short upper bounds for them. It also incorporates a new approach for and hardware realisation of timers characterised by utmost precision and high handling comfort. Such timers are particularly well-suited to serve in distributed real-time systems, since, by employing the exact UTC received from the satellites of GPS (the global navigation and positioning system), synchronisation is not needed anymore.     

A Process Algebraic Approach to the Schedulability Analysis of Real-Time Systems

To engineer reliable real-time systems, it is desirable to detect timing anomalies early in the development process. However, there is little work addressing the problem of accurately predicting timing properties of real-time systems before implementations are developed. This paper describes an approach to the specification and schedulability analysis of real-time systems based on the timed process algebra ACSR-VP, which is an extension of ACSR with value-passing communication and dynamic priorities. Combined with the existing features of ACSR for representing time, synchronization and resource requirements, ACSR-VP is capable of specifying a variety of real-time systems with different scheduling disciplines in a modular fashion. Moreover, we can use VERSA, a toolkit we have developed for ACSR, to perform schedulability analysis on real-time systems specified in ACSR-VP automatically by checking for a certain bisimulation relation.     

Agent-based computer vision in a dynamic, real-time environment

For computer vision systems to operate in many real-world environments, processing must occur in real-time under dynamic conditions. An agent-based methodology offers an approach to increase flexibility and scalability to accommodate the demands of a real-time, dynamic environment. This paper presents an agent-based architecture that uses a utility optimization technique to guarantee that important vision tasks are fulfilled even under resource constraints. To ensure that the processing of vision tasks is both reliable and flexible, multiple behaviors are utilized to accomplish the vision application's requirements. A vision behavior consists of a grouping of vision algorithms and a set of service levels associated with these algorithms. Utility functions are adopted to evaluate the performance of all possible behaviors that can address the requirements of a vision application within resource constraints. The maximum overall utility corresponds to the optimal behavior. Two example systems using this model are presented to show the applicability of the architecture. Experimental results show that this agent-based architecture outperforms traditional non-agent-based approaches.