盾构机动态交互仿真系统的研究与实现

盾构机是用于开挖隧道等地下施工的专用工程机械,有着广阔的应用前 景。但因掘进装备等的高度复杂性,以及地质条件、工况的不确定性等导致的安全问题,对 盾构机的学习和研究带来一定难度。鉴于此,利用VRML、Cult3D、HTML 等开发了一个 基于网络的交互装配、运动仿真和虚拟漫游系统,具有导航漫游、交互操作虚拟对象、信息 查询等功能,形象直观地展示了盾构机的构造和原理,为盾构机的学习和研究提供了一个很 好的平台。     

A generalized framework of dynamic role assignment for robot formation control

A dynamic role assignment algorithm is proposed in the paper for formation control of multiple mobile robots. The goal of the algorithm is to reassign a role for each robot automatically during a formation is forming or switching. Many formation control systems have been successfully implemented and validated by supporting experimental results. Nevertheless, this research aims at providing an efficient algorithm of role assignment for a class of formation control systems employing the concept of combinational optimization problems. Specifically, by exploring spatial relationship between robots and information of obstacles surrounding the robots, a character cost function is found to represent the degree of difficulty for a robot been assigned a specified role in a formation. Instead of using complex cost minimization procedure, a solution is provided by calculating the largest value of character set fitness, and a new formation is selected for robots accordingly. The developed algorithm is applied to the formation control of a group omni-directional driven robots. Simulation and experimentation are performed with real platform to verify the proposed algorithm and the results show that the performance of the proposed dynamic role assignment algorithm is efficient for robot formation control.     

A dynamic data-driven application simulation framework for contaminant transport problems

We describe, devise, and augment dynamic data-driven application simulations (DDDAS). DDDAS offers interesting computational and mathematically unsolved problems, such as, how do you analyze, compute, and predict the solution of a generalized PDE when you do not know either where or what the boundary conditions are at any given moment in the simulation in advance? A summary of DDDAS features and why this is a intellectually stimulating new field are included in the paper.We apply the DDDAS methodology to some examples from a contaminant transport problem. We demonstrate that the multiscale interpolation and backward in time error monitoring are useful to long running simulations.     

A framework for interactive responsive animation

The availability of high‐performance 3D workstations has increased the range of application for interactive real‐time animation. In these applications the user can directly interact with the objects in the animation and direct the evolution of their motion, rather than simply watching a pre‐computed animation sequence. Interactive real‐time animation has fast‐growing applications in virtual reality, scientific visualization, medical training and distant learning. Traditional approaches to computer animation have been based on the animator having complete control over all aspects of the motion. In interactive animation the user can interact with any of the objects, which changes the current motion path or behaviour in real time. The objects in the animation must be capable of reacting to the user's actions and not simply replay a canned motion sequence. This paper presents a framework for interactive animation that allows the animator to specify the reactions of objects to events generated by other objects and the user. This framework is based on the concept of relations that describe how an object reacts to the influence of a dynamic environment. Each relation specifies one motion primitive triggered by either its enabling condition or the state of the environment. A collection of the relations is structured through several hierarchical layers to produce responsive behaviours and their variations. This framework is illustrated by several room‐based dancing examples that are modelled by relations. Copyright © 2000 John Wiley & Sons, Ltd.     

A rigorous framework for interactive robot control

This paper presents a rigorous, analytical framework for interactive control methods such as stiffness and impedance control. This paper does not present a novel synthesis method for robot control design. Rather, it presents a proper framework to analyse controllers for robots whose purpose is to interact energetically with the environment. First geometrical tools are introduced that are used in kinematic and dynamic analysis of the spatio-mechanical systems common in robotics. 'Port behaviour' and 'behavioural deviation' are then defined both intuitively and rigorously. The utility of this framework is demonstrated by a non-trivial example. Concepts of the behavioural approach are used.     

A framework for interactive image color editing

We propose a new method for interactive image color replacement that creates smooth and naturally looking results with minimal user interaction. Our system expects as input a source image and rawly scribbled target color values and generates high quality results in interactive rates. To achieve this goal we introduce an algorithm that preserves pairwise distances of the signatures in the original image and simultaneously maps the color to the user defined target values. We propose efficient sub-sampling in order to reduce the computational load and adapt semi-supervised locally linear embedding to optimize the constraints in one objective function. We show the application of the algorithm on typical photographs and compare the results to other color replacement methods.     

A dynamic evacuation simulation framework based on geometric algebra

Integrating dynamic analysis models into geographic information system (GIS)-based evacuation simulations is important yet complex. Different models must be smoothly assembled according to the data processing flow to obtain a dynamic, data-forced evacuation simulation. However, because of the diversity of data types and dynamic data updating among different models, closely integrated evacuation simulations are complex and inefficient. In this study, geometric algebra (GA) is introduced to develop a dynamic evacuation simulation framework for a hazardous gas diffusion scheme. In the framework, geospatial data are first integrated into a unified virtual scene with different forms of multivector representation. The major simulation models of gas diffusion, risk assessment, and dynamic evacuation routing compose the major steps of the evacuation simulation. On the basis of the generalized multivector structure, dynamic exchange and updating geospatial data at different evacuation steps can be performed seamlessly with the multivector structure and GA operators. The framework is tested with a case study of a three-dimensional residential area, which shows that our framework can support the integration of dynamic evacuation processes and the model integration is direct and smooth. This framework may also provide a new solution for the integration and dynamic data updating in spatiotemporal GIS.     

A framework for interactive work design based on motion tracking,simulation, and analysis

Because of the flexibility and adaptability of humans, manual handling work is still important in industry, especially in assembly and maintenance work. Well‐designed work operation can improve work efficiency and quality; enhance safety, and lower cost. Most traditional methods for work system analysis need physical mock‐ups and are time‐consuming. Digital mock‐up (DMU) and digital human modeling (DHM) techniques have been developed to assist ergonomic design and evaluation for a specific worker population (e.g., 95 percentile); however, the operation adaptability and adjustability for a specific individual are not considered enough. In this study, a new framework based on motion‐tracking technique and digital human simulation technique is proposed for motion–time analysis of manual operations. A motion‐tracking system is used to track a worker's operation while he/she is conducting a manual handling task. The motion data are transferred to a simulation computer for real‐time digital human simulation. The data are also used for motion type recognition and analysis either online or offline for objective work efficiency evaluation and subjective work task evaluation. Methods for automatic motion recognition and analysis are presented. Constraints and limitations of the proposed method are discussed. © 2010 Wiley Periodicals, Inc.     

A multiobject tracking framework for interactive multimedia applications

Automatic initialization and tracking of multiple people and their body parts is one of the first steps in designing interactive multimedia applications. The key problems in this context are robust detection and tracking of people and their body parts in an unconstrained environment. This paper presents an integrated framework to address detection and tracking of multiple objects in a computationally efficient manner. In particular, a neural network-based face detector was employed to detect faces and compute person specific statistical model for skin color from the face regions. A probabilistic model was proposed to fuse the color and motion information to localize the moving body parts (hands). Multiple hypothesis tracking (MHT) algorithm was adopted to track face and hands. In real world scenes extracted features (face and hands) usually contain spurious measurements that create unconvincing trajectories and needless computations. To deal with this problem a path coherence function was incorporated along with MHT to reduce the number of hypotheses, which in turn reduces the computational cost and improves the structure of trajectories. The performance of the framework was validated using experiments on synthetic and real sequence of images.     

A simplified and generalized dynamic simulation of multi-terminal HVDC transmission system

Multi-terminal HVDC transmission systems have a large potential for applications in future power systems. One of the prime requirements of planning-stage investigations and in-operation investigations on the multi-terminal schemes is to have a simplified, dynamic model using a digital computer. One such generalized digital computer program developed, is reported here. The program includes frequency (damping) controllers, power controllers, constant current controllers, limiting nonlinearities, communication delay and central current co-ordinator it can deal with any number of converters connected in any parallel system configuration namely mesh, tapped or a combination of them both. A few case studies are included to demonstrate the ability of the program.     

A concern-oriented framework for dynamic measurements

Evolving software programs requires that software developers reason quantitatively about the modularity impact of several concerns, which are often scattered over the system. To this respect, concern-oriented software analysis is rising to a dominant position in software development. Hence, measurement techniques play a fundamental role in assessing the concern modularity of a software system. Unfortunately, existing measurements are still fundamentally module-oriented rather than concern-oriented. Moreover, the few available concern-oriented metrics are defined in a non-systematic and shared way and mainly focus on static properties of a concern, even if many properties can only be accurately quantified at run-time. Hence, novel concern-oriented measurements and, in particular, shared and systematic ways to define them are still welcome. This paper poses the basis for a unified framework for concern-driven measurement. The framework provides a basic terminology and criteria for defining novel concern metrics. To evaluate the framework feasibility and effectiveness, we have shown how it can be used to adapt some classic metrics to quantify concerns and in particular to instantiate new dynamic concern metrics from their static counterparts.     

An interactive framework for design automation

The paper presents a pilot study of the possibility to design an integrated interactive system for computer aided design of control computer systems, all the way from object system modelling and control system design to electronic design and software production. The study is concentrated on discussing suitable information structures and programming languages for implementation of such a system.     

Open graphical framework for interactive TV

Multimedia end-user terminals are expected to perform advanced user interface related tasks. These tasks are carried out by user interface runtime tools and include, among others, the visualization of complex graphics and the efficient handling of user input. In addition, the terminal’s graphical system is expected, for example, to be able to synchronize audio and video, and control different contexts on the same screen. Finally, the availability of high-level tools to simplify the user interface implementation and the adaptiveness of the user interfaces for a diversity of configurations are, as well, desirable features. This paper presents a layered model that meets the just mentioned requirements. The architecture is divided into five different layers: hardware abstraction layer, multimedia cross platform libraries, graphical environment, GUI toolkit and high-level languages. Moreover, this paper presents the experiences of developing a prototype system based on the architecture, targeted to digital television receivers. In order to evaluate the prototype, some already developed DVB-MHP compliant digital television applications were tested. Finally, the prototype was extended with a high-level profile (i.e., SMIL support) and a low-level one (i.e., access to the framebuffer memory).

A virtual cockpit for a distributed interactive simulation

We developed the virtual cockpit as an inexpensive flight simulator, using off-the-shelf equipment. This system functions as a component of a distributed interactive simulation. Any flight simulator has three principal tasks: image display, image generation, and flight dynamics. We built the flight simulator, the virtual cockpit, using a head-mounted display (HMD) to display the out-the-window imagery and the cockpit interior. The virtual cockpit consists of a Silicon Graphics workstation and supporting hardware components, such as an HMD and position tracker. The software falls into three areas by function: flight dynamics and cockpit instruments; network interface (either SimNet or DIS PDUs); and display of the out-the-window view. The virtual cockpit developed uses a multiprocessor Silicon Graphics Iris (the 4D/440VGXT) connected to a Polhemus Laboratories fiber-optic head-mounted display, a Polhemus magnetic head tracker and a hands-on-throttle-and-stick (HOTAS) by Thrustmaster. The software uses the AT and T C++ translator and the Silicon Graphics C compiler running under Irix 4.0.5. a Unix operating system. We use Software Systems' MultiGen to create the geometric models and the terrain database     

The application of interactive dynamic virtual surgical simulation visualization method

In this paper, an interactive dynamic simulation method is proposed to solve computational models of soft tissue undergoing large deformation, collision detection, and volume conservation in medical surgical simulation visualization. During the process of implementation of the interactive dynamic simulation method, the point-based method is used to simulate the elastic solids undergoing large deformations and the position-based method is used to simulate the objects collision, friction and volume conservation. Numerical results demonstrate that the proposed method improves the efficiency and stability of the response of heterogeneous soft tissue undergoing contact or even the multi-organs interactions, and it can be extended to interactive biopsy and cutting simulation.

     

A computing framework for integrating interactive visualization in HPCC applications

Network-based concurrent computing and interactive data visualization are two important components in industry applications of high-performance computing and communication. We propose an execution framework to build interactive remote visualization systems for real-world applications on heterogeneous parallel and distributed computers. Using a dataflow model of a commercial visualization software AVS in three case studies, we demonstrate a simple, effective, and modular approach to couple parallel simulation modules into an interactive remote visualization environment. The applications described in this paper are drawn from our industrial projects in financial modeling, computational electromagnetics and computational chemistry. Copyright © 1999 John Wiley & Sons, Ltd.     

A framework for dynamic multiple-criteria decision making

The classic multiple-criteria decision making (MCDM) model assumes that, when taking a decision, the decision maker has defined a fixed set of criteria and is presented with a clear picture of all available alternatives. The task then reduces to computing the score of each alternative, thus producing a ranking, and choosing the one that maximizes this value.However, most real-world decisions take place in a dynamic environment, where the final decision is only taken at the end of some exploratory process. Exploration of the problem is often beneficial, in that it may unveil previously unconsidered alternatives or criteria, as well as render some of them unnecessary.In this paper we introduce a flexible framework for dynamic MCDM, based on the classic model, that can be applied to any dynamic decision process and which is illustrated by means of a small helicopter landing example. In addition, we outline a number of possible applications in very diverse fields, to highlight its versatility.