Sliding mode control for multi-agent systems under a time-varying topology

This paper addresses the tracking problem of a class of multi-agent systems under uncertain communication environments which has been modelled by a finite number of constant Laplacian matrices together with their corresponding scheduling functions. Sliding mode control method is applied to solve this nonlinear tracking problem under a time-varying topology. The controller of each tracking agent has been designed by using only its own and neighbours’ information. Sufficient conditions for the existence of a sliding mode control tracking strategy have been provided by the solvability of linear matrix inequalities. At the end of this work, numerical simulations are employed to demonstrate the effectiveness of the proposed sliding mode control tracking strategy.     

Face tracking with automatic model construction

This paper describes an active model with a robust texture model built on-line. The model uses one camera and it is able to operate without active illumination. The texture model is defined by a series of clusters, which are built in a video sequence using previously encountered samples. This model is used to search for the corresponding element in the following frames. An on-line clustering method, named leaderP is described and evaluated on an application of face tracking. A 20-point shape model is used. This model is built offline, and a robust fitting function is used to restrict the position of the points. Our proposal is to serve as one of the stages in a driver monitoring system. To test it, a new set of sequences of drivers recorded outdoors and in a realistic simulator has been compiled. Experimental results for typical outdoor driving scenarios, with frequent head movement, turns and occlusions are presented. Our approach is tested and compared with the Simultaneous Modeling and Tracking (SMAT) [1], and the recently presented Stacked Trimmed Active Shape Model (STASM) [2], and shows better results than SMAT and similar fitting error levels to STASM, with much faster execution times and improved robustness.     

Robust tracking control design for uncertain robotic systems with persistent bounded disturbances

In this study, a robust nonlinear L_∞‐gain tracking control design for uncertain robotic systems is proposed under persistent bounded disturbances. The design objective is that the peak of the tracking error in time domain must be as small as possible under persistent bounded disturbances. Since the nonlinear L_∞ ‐gain optimal tracking control cannot be solved directly, the nonlinear L_∞ ‐gain optimal tracking problem is transformed into a nonlinear L_∞ ‐gain tracking problem by given a prescribed disturbance attenuation level for the L_∞ ‐gain tracking performance. To guarantee that the L_∞ ‐gain tracking performance can be achieved for the uncertain robotic systems, a sliding‐mode scheme is introduced to eliminate the effect of the parameter uncertainties. By virtue of the skew‐symmetric property of the robotic systems, sufficient conditions are developed for solving the robust L_∞ ‐gain tracking control problems in terms of an algebraic equation instead of a differential equation. The proposed method is simple and the algebraic equation can be solved analytically. Therefore, the proposed robust L_∞ ‐gain tracking control scheme is suitable for practical control design of uncertain robotic systems. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Students' perceptions of ICT-related support in teaching placements

Abstract Recent research has shown that students' use of information and communications technology (ICT) on teaching practice is necessary for effective future use of ICT in the classroom. However, this paper reports that there are a number of factors affecting the use of ICT by student-teachers in their school placements. All 110 student-teachers attending one university's eight Postgraduate Certificate in Education (PGCE) courses completed a questionnaire on their attitudes to ICT in learning and teaching and their initial experiences of the application of ICT in schools. In-depth interviews with the student-teachers, as well as univer-sity tutors and teachers, revealed a range of issues that reflected how student-teachers perceive their school-based ICT training and what they think could improve their experiences. Recommendations are offered for the improvement of the ICT school experiences for student-teachers until teacher training is completed and improved ICT infrastructure is in place in schools. The overriding conclusion is that schools must be supported and resourced properly, and teachers must have effective ICT training, before improvements in school-based ICT development for student-teachers can be achieved.     

Speech technology for automatic teller machines: an investigation of user attitude and performance

Despite the success and widespread use of Automatic Teller Machines (ATMs), a significant proportion of bank customers can not or will not use them, or experience difficulties in their interactions. Speech technology has been suggested as a means by which non-users might be encouraged to use ATMs, while simultaneously improving usability for all. The potential advantages of speech interfaces include hands-free and eyes-free use for physically- and visuallyimpaired users, and improved ease and speed of use through increased ‘naturalness’ of the interaction. This study investigated user attitudes to the concepts of a speech-based ATM, via large-scale survey and a series of focus groups. Objective performance was also considered in user trials with a prototype speech-driven ATM. The idea of using speech for ATM transactions led to a number of concerns. Privacy (the concern over one's personal financial details being overheard) and security (the fear of potential attackers hearing the user withdraw cash) were the major reasons given. The user trials confirmed that possible solutions, such as the adoption of a hood over the ATM or the use of a telephone handset as the speech input/output device, were ineffective. Groups of impaired users, particularly visually-impaired subjects, were more positive about the concept of speech, citing various difficulties with current visual-manual interactions. Most non-users, however, would not be encouraged to use ATMs with the addition of speech. The paper discusses these and other issues relating to the likely success of using speech for ATM applications.     

A probabilistic integrated object recognition and tracking framework

This paper describes a probabilistic integrated object recognition and tracking framework called PIORT, together with two specific methods derived from it, which are evaluated experimentally in several test video sequences. The first step in the proposed framework is a static recognition module that provides class probabilities for each pixel of the image from a set of local features. These probabilities are updated dynamically and supplied to a tracking decision module capable of handling full and partial occlusions. The two specific methods presented use RGB color features and differ in the classifier implemented: one is a Bayesian method based on maximum likelihood and the other one is based on a neural network. The experimental results obtained have shown that, on one hand, the neural net based approach performs similarly and sometimes better than the Bayesian approach when they are integrated within the tracking framework. And on the other hand, our PIORT methods have achieved better results when compared to other published tracking methods in video sequences taken with a moving camera and including full and partial occlusions of the tracked object.     

相似点区段负责制的改进区域生长法及其应用

区域生长法被广泛应用于对特定目标的选取,但其生长速度缓慢的特点又限制了其在某些领域的应用.为此,提出一种基于相似点区段负责制的像素点进出堆栈管理方法,有效的提高了区域生长的效率.在此基础上,结合链码法边界跟踪对生长过程中区域内部出现的孔洞实现区域补偿,建立了针对链状藻细胞分析统计的有效应用系统.     

R-M不稳定性数值模拟方法

通常,界面追踪方法都是由界面将计算区域分割为多个部分来分别处理,同时用求解黎曼问题来追踪全部波系的发展。然而在多维情况下,波系间相互作用的黎曼问题将非常复杂且目前尚处于分析阶段,故在实际应用中只能追踪界面本身。提出了一种新的界面追踪方法,该方法只追踪界面的发展而不再追踪波系,使计算量和复杂性大大减少并保持了原界面追踪方法精确捕捉界面的特点,数值结果令人满意。     

逆指令流与指令队列预取反跟踪技术

介绍一种逆指令流的实现方法，同时把它与指令队列预取法结合在一起实现了反跟踪，使其成为一种综合性的威力较强的反动态跟踪技术     

Defects tracking matrix for mass customization production based on house of quality

The vision of mass customization has driven a movement toward low volume, high variety mass customization production (MCP) at low price. However, defect identification and defect tracking in such systems are extremely difficult because of the frequent reconfiguration needed by the number of different part types and the interruption of the information flow about quality with each reconfiguration of the system. It is important to quickly rebuild quality information flow with MCP system’s reconfiguration synchronously. This paper introduces a defect tracking method based on Quality Function Deployment for every MCP system module. A defects tracking matrix (DTM) based on the House of Quality directly connects manufacturing technologies with quality defects inside a MCP module. Each MCP reconfiguration requires the DTMs’ rearrangement and DTM-chain is proposed. A dynamic reconstructing algorithm synchronizes the DTM-chain with each MCP reconfiguration. A case study demonstrates the usefulness of the DTM and DTM-chain.