空间多刚体系统姿态的协同控制

将一种针对多个一般非线性系统的基于输出反馈的协同控制方法应用在采用四元数法描述的空间多个刚体姿态的协同控制系统中去,给出了空间多刚体系统姿态协同控制问题有解的充分条件,并设计了多刚体系统姿态的协同控制律．算例仿真结果表明,此法设计的协同控制器能够稳定控制描述各个刚体系统的姿态四元数,使其渐近稳定．     

一种新的多刚体系统的存储方法

指出了目前多刚体系统数据存储的不足,运用图论的概念和建模理论,分析了多刚体系统的结构图和有向图之间的关系,提出了一种新的基于十字链表的链式存储模型.该存储模型不仅解决了复杂多刚体系统的存储结构问题,而且避免了非树形多刚体向树形多刚体的切除转换,使非树形多刚体系统与树形多刚体系统从数学建模到数据存储达到高度一致.     

多刚体系统的一致性控制研究

基于非自治级联系统理论,以非完整移动机器人为研究对象,研究多刚体系统的一致性问题,提出了一种新的分布式控制器。通过引入持续激励扰动项,验证了无论参考信号是否为持续激励信号,所提出的控制器都能实现系统一致性的目的,且能一致到期望的参考值。利用李雅普诺夫方法对系统进行了稳定性分析。最后,对所提控制器进行数值仿真,结果验证了所提出的控制器的有效性。     

含摩擦滑移铰及驱动约束多刚体系统数值算法

研究了具有驱动约束及非光滑滑移铰多体系统动力学方程的建模与数值计算方法．将驱动约束视为非定常约束,非光滑滑移铰视为双边定常约束,滑移铰的摩擦模型采用库仑摩擦模型;应用第一类Lagrange方程建立系统的动力学方程,应用距离函数建立滑移铰的约束方程;将线性互补方法和Baumgarte约束稳定化方法引入,以解决滑移铰法向约束力的计算以及约束方程违约问题．最后应用曲柄摇杆机构作为算例,说明该方法的有效性．     

基于十字链表的多刚体系统的数据存储

针对多刚体系统数据存储的不足,对多刚体系统的结构图与图论的有向图之间的关系进行了研究,提出了一种新的基于十字链表的链式存储模型.该存储模型不但较好地解决了复杂多刚体系统的存储问题,而且充分满足了在存储物理多刚体系统时的结构正确性和数据完备性要求,避免了非树形多刚体向树形多刚体的回路切除转换,使多刚体系统在数学建模与数据存储方面达到高度一致.     

含干摩擦多体系统Lagrange方程的数值算法

利用第一类Lagrange方程建立了固定约束面含干摩擦的多体系统动力学方程,将摩擦力的广义力用矩阵形式描述．利用增广法。将微分-代数方程转换成常微分方程,并用矩阵形式给出,提高了计算效率．最后用算例说明该方法的有效性．     

一类空间机械臂系统的自适应控制与鲁棒控制

讨论载体位置与姿态均不受控制的自由浮动空间机械臂系统的控制问题。基于增广列反馈控制模型,提出当载荷参参数不确定时空间机械臂追踪惯性空间期望轨迹的自适应和鲁棒控制方法,通过仿真运算,证实了方法物有效性。     

基于碰撞响应的三维空间多刚体实时运动仿真

该文将计算机科学与理论力学相结合,以刚性球体为例介绍了多刚体物理运动仿真的步骤和方法。首先论述了单个及多个刚体的运动仿真步骤以及应用叠加原理计算合力及合力矩的方法。然后,针对刚体运动中的不同碰撞响应类型：碰撞接触与临时接触,提出分别建立不同的碰撞响应力学模型,前者采用动量及动量矩定理建立响应模型,后者通过分析刚体的受力和运动状态建立相应的动力学模型。最后,详细讨论了刚性球体的碰撞仿真,包括它的碰撞测定、碰撞响应模型的建立及求解等,实现了三维空间中刚性球体实时、精确、快速的运动仿真,为以后多刚体大规模仿真奠定基础。     

多刚体动力学仿真的李群变分积分算法

刚体的构形可用其质心位置和姿态矩阵描述.刚体的位置可以在欧几里得空间中表示,但是其姿态矩阵是在李群上演化的.由于李群独特的非线性性质,基于欧氏空间的多体动力学建模与数值算法难以完全真实地描述系统的动力学特性,特别是长时间历程的动力学特性.本文基于几何力学理论,首先根据离散Hamilton变分原理与离散Legendre变换,建立了多刚体系统的Hamilton体系李群变分积分公式.其次,给出李群变分积分公式的两种离散格式：一般离散格式和RATTLie离散格式.最后,采用这两种不同离散格式构建的算法计算了重力作用下空间刚体双摆的动力学问题,对比研究了算法在保持系统群结构、系统能量等方面的性质.计算结果表明,RATTLie离散格式较一般格式精度更高,且能更好地保持系统群结构与能量.     

中心刚体-柔性梁应变反馈多目标优化控制

本文针对柔性结构在轨组装任务背景,将自动飞船和待运送部件分别简化为中心刚体和柔性梁附件,研究自由漂浮中心刚体-柔性梁系统的动力学与控制问题.首先基于小变形和低转速假设,将梁用假设模态法离散,采用Lagrange方程导出系统动力学方程.继而设计一种带有应变反馈的PD控制律用于完成中心刚体的状态镇定以及柔性梁振动抑制.此外,本文还使用遗传算法对控制器中的参数进行多目标优化.最后,通过数值算例验证了所设计控制器的有效性.     

A Comparison of Fuzzy and CPWL Approximations in the Continuous-time Nonlinear Model-predictive Control of Time-delayed Wiener-type Systems

This paper deals with a novel method of continuous-time model-predictive control for nonlinear time-delayed systems. The problems relating to time delays are solved by incorporating the Smith-predictor scheme in a control-law derivation. A nonlinear-mapping approximation, employing either continuous piece-wise linear functions or a fuzzy system, is also an integral part of the control scheme, and thus removes the need for output-function invertibility. An illustrative experiment is conducted to compare the control quality in both approaches when tackling a time-delayed Wiener-type system control.     

Kinematic simulation of human gait with a multi-rigid-body foot model

The paper builds a multi-rigid-body model of human with a 4-rigid-body foot in the 3D CAD software Solidworks,based on human anatomy.By controlling the rotation of the ankle and major joints of human body while walking,the Kinematic simulation was performed in the dynamics simulation software ADAMS.The paper analyzes the simulate results and points out deficiencies in the current work and the direction of research efforts in future.     

空间离群点的模型与跳跃取样查找算法

目前无论是查找一般的离群点,还是空间离群点,都强调非空间属性的偏离,但在图像处理、基于位置的服务等许多应用领域,空间与非空间属性要综合考虑。为此,首先提出了一个综合考虑两者的空间离群点定义,然后提出了一种新的基于密度的空间离群点查找方法——基于密度的跳跃取样空间离群点查找算法DBSODLS。由于已有的基于密度的离群点查找方法对每一点都要求进行邻域查询计算,故查找效率低,而该算法由于可充分利用已知的邻居信息,即不必计算所有点的邻域,从而能快速找到空间离群点。分析与试验结果表明,该算法时间性能明显优于目前已有的基于密度的算法。     

Analysis of Flexible Multibody Systems with Intermittent Contacts

This paper is concerned with the dynamic analysis of flexible,nonlinear multibody systems undergoing intermittent contacts. Contact isassumed to be of finite duration, and the forces acting between thecontacting bodies which can be either rigid or deformable are explicitlycomputed during simulation. The modeling of contact consists of threeparts: a number of holonomic constraints that define the candidatecontact points on the bodies, a unilateral contact condition which istransformed into a holonomic constraint by the addition of a slackvariable, and a contact model which describes the relationship betweenthe contact force and the local deformation of the contacting bodies.This work is developed within the framework of energy preserving anddecaying time integration schemes that provide unconditional stabilityfor nonlinear, flexible multibody systems undergoing intermittentcontacts.     

Clicks and Mortar: Balancing Brick and Mortar Business Strategy and Operations with Auxiliary Electronic Commerce

Balancing business strategy and operations between electronic commerce and brick and mortar channels (clicks and mortar) is an ongoing challenge for many businesses. A group of traditional brick and mortar firms were examined in order to understand how they balance strategy and operations between electronic commerce and traditional (brick and mortar) business channels. Results of the study indicated several distinct approaches to achieving this balance. Most of these approaches belie the idea that it is uniformly beneficial to deploy electronic commerce to mirror all of a firm's primary value chain activities. Instead, the study indicated that firm involvement with electronic commerce is often best minimized for the sake of successful business strategy and operations. Despite the necessarily limited and auxiliary role of electronic commerce for traditional firms, it still can help in supporting these firms' business to consumer operations in some surprising ways.     

新型高线性度分段激磁式扭矩传感器的研究

扭矩的准确测量对实现机械设备的自动控制有着重要的作用,为此,设计了一种新型分段激磁的高线性度扭矩传感器。传感器的激磁绕组为分段式,传感器转轴受到扭矩作用时,输出绕组经过电磁耦合输出与负载扭矩呈正比关系的感应电势,并找到了传感器输出特性呈较高度线性时,激磁线圈与输出线圈的匝数比的范围约为0.56~0.59。推导了传感器的输出特性,构建了传感器的数学模型。最后采用扭转试验机对传感器进行了标定,实验结果表明传感器的灵敏度约为1.05 m V/(N·m),重复性误差约为±0.38%,非线性误差约为±0.26%,迟滞误差约为±0.37%。     

面向2D对象形状识别的空间模糊查询研究

基于空间形状的查询与认知主体的空间推理密切相关。从空间认知的角度,通常希望查询结果是一类形状结构相似的对象集合。以形状的不确定性表达和模糊查询为研究内容,提出一种面向2D对象形状识别的空间查询方法--向心包络算法。算法将对象划分为以最大内径中心为公共点的三角形集合,在此基础上建立相应的形状度量方法,通过提取所有顶点关于对象整体结构的形状影响因子求得对象之间的形状相似度,并建立与模糊形状谓词的匹配关系。实验表明,该方法可以实现2D对象的空间模糊查询,且查询结果与模糊形状谓词基本一致。     

Exponentially Accurate Approximations to Piece-Wise Smooth Periodic Functions

A family of simple, periodic basis functions with built-in discontinuities are introduced, and their properties are analyzed and discussed. Some of their potential usefulness is illustrated in conjunction with the Fourier series representation of functions with discontinuities. In particular, it is demonstrated how they can be used to construct a sequence of approximations which converges exponentially in the maximum norm to a piece-wise smooth function. The theory is illustrated with several examples and the results are discussed in the context of other sequences of functions which can be used to approximate discontinuous functions.     

Knowledge-intensive systems in the social service agency: Anticipated impacts on the organisation

Shrinking resources and the increasing complexity of clinical decisions are stimulating research in knowledge-intensive computer applications for the delivery of social services. The expected benefits of knowledge-intensive applications such as expert systems include improvement in both the quality and the consistency of service delivery, augmentation of institutional memory, and reduced labour costs through greater reliance on paraprofessionals. This paper analyses the likely impacts of knowledge-intensive systems on social service organisations, drawing on trends in related service-delivery fields, and on known impacts of computer applications in organisations. A structural change may be anticipated: decision making and planning functions will shift increasingly from social service professionals to administrators.