基于多线谱驱动的虚拟人手运动及约束控制

针对现有手部运动模拟控制的复杂性,通过分析人手解剖学结构及运动特性,提出了基于多线谱控制的虚拟人手运动及控制机制。针对单指运动,通过控制该指上的多条肌肉归一化收缩量,驱使单指关节的灵活运动;在多指协同运动中,由于相邻手指之间存在运动促进和制约的关系,因此要考虑其他手指的影响,根据其约束关系,控制相应的肌肉收缩,实现多指协同运动。实验表明,所建立的控制机制能较好地仿真单指及多指间的各种运动,在多线谱的控制下,能够方便快捷地仿真多种手势及手语,且运动效果逼真,手部运动自然灵活。     

基于发音运动特征的舌部肌肉建模及仿真

人舌结构较为复杂,运动灵活,在虚拟人物发音及表情运动过程中起着关键的作用,但现有舌部模型结构较单一,实现的虚拟运动相对简单,描述能力不足,且需要大量数据驱动。针对以上问题,通过对舌部解剖结构的研究,提出一种基于肌肉运动特征的舌部模型及控制方法。将舌部内外肌群按其运动及发音功能进行分类,仅需获得多条肌肉不同的收缩量,即可利用各自的控制函数确定出参数值,进而实现模型前升高、后升高和谷形等多种常见运动。实验结果表明,该方法能够较为灵活便捷地控制虚拟舌体,仿真出符合生理特征的多种舌部运动。     

基于解剖学的人手肌肉建模技术

为实现仿真手在运动过程中符合人手的生理特性及运动特点,文中通过分析手的解剖结构,总结控制手部运动和形状的约束参数,采用层次建模方法,先建立用线段表示的含有约束参数的手部骨骼模型,然后在此基础上根据手部的特征横截面确定特征多边形,采用NURBS面片拟合的方法建立依附于骨骼之上的肌肉模型.此方法建立的手部模型在运动仿真过程中,手部肌肉以对应的骨骼为轴线并随着骨骼各个参数的变化而发生相应的变化,最终取得良好的仿真效果.     

基于解剖学的人手肌肉建模技术

为实现仿真手在运动过程中符合人手的生理特性及运动特点，文中通过分析手的解剖结构，总结控制手部运动和形状的约束参数．采用层次建模方法，先建立用线段表示的含有约束参数的手部骨骼模型，然后在此基础上根据手部的特征横截面确定特征多边形，采用NURBS面片拟合的方法建立依附于骨骼之上的肌肉模型。此方法建立的手部模型在运动仿真过程中，手部肌肉以对应的骨骼为轴线并随着骨骼各个参数的变化而发生相应的变化，最终取得良好的仿真效果。     

基于运动分解的嘴部肌肉建模仿真

现有虚拟嘴部肌肉建模多采用传统的Water肌肉分类方法,运动控制较为独立,缺乏对运动间相关性的研究。提出了一种基于运动分解的嘴部肌肉建模及控制方法。首先根据解剖结构及肌肉运动特征,将嘴部自身运动分解为凸唇、翘唇和开合三个基本运动单元;其次现有模型中括约肌运动方式是向中心收缩或扩散,难以表现凸翘等嘴部运动,为此提出了弧状肌模型,并通过控制三个运动参数,结合其它嘴周围肌组合出不同的嘴部运动。实验表明,新方法能够较真实地仿真出嘴部的多种自然运动,控制较为便捷。     

基于实时内核的双起升双吊具桥吊实时仿真平台

双起升双吊具桥吊是一种复杂的多电机传动机械,其多电机协调控制需要实现桥吊操作的准确性、安全性和快速性;文中针对一种双起升双吊具桥吊实验装置的多电机协调控制的需要,构建了一个桥吊多电机实时仿真控制平台,提出了一种基于Real-TimeWorkshop(RTW)的实时内核的混合仿真实验构架,采用了S函数设计开发运动控制器驱动模块,并通过调用设备驱动函数操作运动控制器,最终实现桥吊多电机协调控制的方法;该方案具有技术先进、结构简单、使用灵活、成本低廉的特点,能够方便地实现针对双起升双吊具桥吊控制方法的数字仿真和半实物仿真。     

虚拟维修样机中机构的运动行为仿真

机构由于其运动特性的复杂性、多样性而成为虚拟维修样机研究的难点之一。针对虚拟维修样机中机构的运动行为仿真问题,在研究机构的分类以及构件之间关系的基础上,定义了十种运动副,提出按机构的构造进行分类,然后根据构件间的连接方式即运动副来建立运动仿真的思路;在JACK软件平台下,研究了采用约束关系建立机构运动仿真和采用脚本控制建立机构运动仿真的方法,并进一步分析了这两种方法的适用条件、范围以及其局限性,提出采用约束关系与脚本控制相结合的方法来建立机构的运动仿真;最后以某炮闩的发射机为例进行验证。     

基于Simulink的鱼雷控制系统仿真

鱼雷是一种水下自主航行的运动体,其运动控制系统复杂,仿真建模难度大。该文首先描述了鱼雷动力学和运动学数学模型,给出了鱼雷水下空间运动的控制系统数学模型,详细论述了Simulink的鱼雷控制系统建模方法以及S功能函数的实现方法,并建立了Simulink仿真图形模型,最后给出了鱼雷控制系统的仿真方法,并对仿真结果进行了分析讨论。结果表明,所采用的Simulink与C／C 混合编程仿真方法,能够方便地建立鱼雷等复杂系统的图形模型,具有直观、高效、灵活的特点。     

基于动态规划的约束优化问题多参数规划求解方法及应用

结合动态规划和单步多参数二次规划, 提出一种新的约束优化控制问题多参数规划求解方法. 一方面能得到约束线性二次优化控制问题最优控制序列与状态之间的显式函数关系, 减少多参数规划问题求解的工作量; 另一方面能够同时求解得到状态反馈最优控制律. 应用本文提出的多参数二次规划求解方法, 建立无限时间约束优化问题状态反馈显式最优控制律. 针对电梯机械系统振动控制模型做了数值仿真计算.     

一种面向云服务组合的策略冲突检测机制

针对云服务组合的策略冲突问题,研究了云服务中属性间关系及组件服务间组合关系的特点,提出了基本类型冲突、层次关系冲突、互斥关系冲突、组合关系约束冲突四种冲突类型;设计了能够直观表达策略中多种关系的策略生成图模型,该模型具有结构灵活、易于更新和动态扩展的优点;将冲突检测问题转化为图的连通性问题,提出了一种基于策略生成图模型的冲突检测机制,实现了对云环境下大规模策略集中冲突策略的高效检测。最后,开展仿真实验,验证、评估了检测机制的有效性和检测效率。     

Analysing students' shared activity while modeling a biological process in a computer-supported educational environment

Abstract  This paper reports on a case study with three dyads of high school students (age 14 years) each collaborating on a plant growth modeling task in the computer-supported educational environment ' ModelsCreator '. Following a qualitative line of research, the present study aims at highlighting the ways in which the collaborating students as well as the facilitator who supported them are engaged in the computer-based modeling 'activity'. The analysis is carried out with a two-level analytic tool that has been derived within the theoretical framework of 'activity theory'. Our results show that a wide range of modeling 'operations' is activated in the context of the three major modeling 'actions' of 'analysis', 'synthesis' and 'testing-interpreting', which take place in the light of the facilitator-driven 'action' of cognitive and technical support. Moreover, these actions are combined into 'modeling units' of various forms which are repeated several times until the modeling process comes to an end. These many-fold repeats of the 'modeling unit' appear to shape a pattern which characterizes the computer-supported shared 'activity' as a whole.     

Context-aware garment modeling from sketches

Modeling of realistic garments is essential for creating believable virtual environments. Sketch-based modeling of garments presents an appealing, easy to use alternative to the established modeling approaches which are time consuming and require significant tailoring expertise. Unfortunately, the results created using existing sketch-based methods lack realism. Driven by human perception of garment sketches, we propose a context-aware garment sketch interpretation based on a set of observations about key factors that affect the shape of garments. Based on this analysis we develop a geometric method for sketch-based modeling of garments which obtains more realistic results than previous techniques. We demonstrate the effectiveness of our method on a variety of inputs and validate our approach via a user study where viewers were asked to compare the believability of our outputs versus previous ones.     

A ‘context-aware’ and agent-centric perspective for the alignment between individuals and organizations

The enterprise modeling field aims at representing organizations from several, inter-related perspectives. A number of enterprise modeling frameworks have been developed providing models, methods and tools that enable to communicate the structure and processes of organizations. These frameworks have been used both for systems development and organizational analysis ends, where the latter mainly focuses process (re)design efforts. We argue that enterprise modeling frameworks can be used for other kinds of organizational analysis. In particular, they can be used to capture and model work practices, human multitasking at work, and to compare models describing pre-defined behavior with actual execution.     

三维CAD 混合建模技术研究

三维数字化建模主要有两种技术：一是参数化建模,二是直接建模。但这 两种技术在实际应用中均存在缺陷。论文将两种建模方法融合在一起形成混合建模技术,能 更好地体现设计者的意图,提高设计效率。     

三维地质模型分析概述

由于三维地质建模需要对矿体的品位等属性信息进行详细的描述,所以三维地学建模须采用基于体元的方法建模,也可以由表面模型栅格化为体元模型。综述了现在常用的三维地质建模的一般方法,实体模型、四面体、块体模型、结构实体几何、似三棱柱等,并对各自的优缺点进行了分析,着重介绍了基于体元的建模方法,可为三维地质建模初学者提供一定的参考。     

A procedure for building product models

The application of product modeling in manufacturing companies raises the important question of how to model product knowledge in a comprehensible and efficient way. An important challenge is to qualify engineers to model and specify IT-systems (product models) to support their specification activities. A basic assumption is that engineers have to take the responsibility for building product models to be used in their domain. To do that they must be able to carry out the modeling task on their own without any need for support from computer science experts. This paper presents a set of simple, easily adaptable concepts and methods for modeling product knowledge. The concepts and methods are based on well-defined concepts and methods from data modeling (object oriented analysis) and domain modeling (product modeling). The concepts are general and can be used for modeling all types of specifications in the different phases in the product life cycle. The modeling techniques presented have been tested in different companies and have proved to work.     

MuscleBuilder: A modeling tool for human anatomy

A traditional multi-layered approach is adopted to human body modeling and deformation. The model is split into three general anatomical structures: the skeleton, musculature and skin. It is shown that each of these layers is modeled and deformed by using fast, procedural, ad-hoc methods that can painlessly be reimplemented. The modeling approach is generic enough to handle muscles of varying shape, size and characteristics and does not break in extreme skeleton poses. It is also described that the integrated MuscleBuilder system whose main features are: i) easy and quick creation of muscle deformation models; ii) automatic deformation of an overlying skin. It is shown that visually realistic results can be obtained at interactive frame rates with very little input from the designer.     

A Curvature and Density‐based Generative Representation of Shapes

This paper introduces a generative model for 3D surfaces based on a representation of shapes with mean curvature and metric, which are invariant under rigid transformation. Hence, compared with existing 3D machine learning frameworks, our model substantially reduces the influence of translation and rotation. In addition, the local structure of shapes will be more precisely captured, since the curvature is explicitly encoded in our model. Specifically, every surface is first conformally mapped to a canonical domain, such as a unit disk or a unit sphere. Then, it is represented by two functions: the mean curvature half‐density and the vertex density, over this canonical domain. Assuming that input shapes follow a certain distribution in a latent space, we use the variational autoencoder to learn the latent space representation. After the learning, we can generate variations of shapes by randomly sampling the distribution in the latent space. Surfaces with triangular meshes can be reconstructed from the generated data by applying isotropic remeshing and spin transformation, which is given by Dirac equation. We demonstrate the effectiveness of our model on datasets of man‐made and biological shapes and compare the results with other methods.     

Location-based services and GIS in perspective

This paper examines location-based services (LBS) from a broad perspective involving definitions, characteristics, and application prospects. We present an overview of LBS modeling regarding users, locations, contexts and data. The LBS modeling endeavors are cross-examined with a research agenda of geographic information science. Some core research themes are briefly speculated.     

SOA全生命周期建模方法综述

在介绍SOA(面向服务的架构)项目实施过程的基础上,从SOA全生命周期的视角,着重从方法论上对实施SOA项目所涉及到的业务流程建模、服务建模、数据建模、服务集成建模和业务监控建模进行了分析与评述,并提供了一些新的解决思路,同时指出了SOA建模领域的一些研究热点及趋势。