颞骨手术虚拟触感装置设计及其运动学分析

针对现有颞骨手术术前培训手段存在的问题,设计了一种具有结构简单、位姿解耦、自重平衡特点的5自由度力反馈触感装置。其采用水平放置的平行四边形结构,使得前后和左右两个位置自由度均满足重力平衡;对于后3个姿态自由度,采用驱动电机补偿的方式实现了完全重力补偿,进而实现了整个触感装置完全重力平衡;在触感装置结构设计的基础上对触感装置开展了工作空间分析,针对触感装置的运动学模型问题,基于旋量法建立了触感装置的正逆运动学模型;利用该模型,通过推导其末端雅可比矩阵,建立了速度模型;最后,通过Matlab对机构的条件数进行了分析计算,对机构灵活性进行了评价。研究结果表明:所设计的机构满足工作空间需求,其灵活性较好、精度较高,验证了触感装置机构设计的合理性。     

面向虚拟制造和装配的触感接口

触感接口是实现操作者与虚拟环境之间触感信息交互的关键环节。从触感的生理学基础入手 ,介绍了与触感接口相关的概念与技术内涵 ,概述了触感接口技术的特点与应用现状 ,并探讨了其存在的问题与发展趋势     

面向虚拟制造和装配的触感接口

触感接口是实现操作者与虚拟环境之间触感信息交互的关键环节,从触感的生理学基础入手,介绍了与触感接口相关的概念与技术内涵,概述了触感接口技术的特点与应用现状,并探讨了其存在的问题与发展趋势。     

触感装置滑模控制设计研究

针对触感装置的非线性采用滑模控制对其进行控制研究,并设计干扰观测器对模型不确定性及外界干扰进行观测,为力位补偿打下基础,同时改善了系统控制性能。     

2自由度触觉交互装置驱动性能分析

触觉交互装置的驱动性能是衡量触觉交互装置设计成败的重要指标,也是触觉交互装置设计的主要依据。以自行设计的2自由度闭环触觉交互装置为对象,对触觉交互装置驱动性能进行了研究,提出了评价触觉交互装置正向和反向驱动性能的方法。在对机构进行静力学和动力学分析的基础上,给出了衡量驱动性能的具体指标。     

基于虚拟环境的遥操作机器人主从交互系统设计

针对遥操作机器人系统中的时延问题,设计了一种基于虚拟环境的机器人遥操作主从交互系统.利用Java/Java3D进行分布式虚拟环境以及虚拟机器人的三维建模;通过JNI方法建立主手设备与虚拟环境的交互接口.操作者通过操纵主手而对虚拟机器人进行关节驱动,提高了主从控制的实时性.     

具有力-位补偿的触感装置控制体系结构

针对为改善系统透明性所遇到的由触感装置的力-位耦合特性所造成的两个主要问题,首先,介绍了双端口网络方法描述触感装置的系统特征;接着,阐述了四通道双向控制体系结构,并讨论在此体系结构下演化出的两种控制方法:位置误差控制和直接力反馈控制;最后,提出了一种模型参考力-位补偿策略,将力-位单元嵌入到直接力反馈控制体系结构中.研究结果表明,该控制体系结构可以实现触感装置的精确位置控制和真实力觉感知.     

VR环境下的虚拟手自然交互方法研究

针对当前基于VR的虚拟仿真系统存在的沉浸式交互体验感较差、物理效果较难模拟等问题,提出一种VR环境下基于物理属性的虚拟手自然交互方法.将虚拟物体物理属性与启发式交互方法相结合,避免了交互过程中虚拟手与虚拟物体相互穿透,实现了虚拟物体位姿随虚拟手接触点变化实时调整与自适应.最后,借助HTC VIVE虚拟现实套件以及Leap Motion体感控制器所搭建的沉浸式人机交互环境,对各类虚拟物体的交互操作进行实例验证并测试计算效率,验证了该方法的可行性.     

压电驱动器激励的触觉显示器结构设计及有限元分析

本文针对表面纹理质地触感再现,借助有限元软件ANSYS11.0,设计了压电驱动器激励的触觉显示器。利用压电陶瓷的逆压电效应,在压电双晶陶瓷片上下表面施加稳态正弦激励电压,激发整个装置共振;调节电压的峰峰值和频率,激发出不同的振动模式以得到不同的振动响应,从而产生不同的触感。根据粗糙度的定义证实了装置的可行性,为最终研制出一种组合式、高密度、可独立精确控制各振子振动模式的触觉显示器装置提供了可靠的依据。     

机器人触感装置力位解耦控制策略研究

通过将触感装置关节处的摩擦计入到系统的动力学模型中，在现有的力位补偿方法基础上分别建立摩擦力、重力、惯性力补偿模型进行附加力补偿，对于附加位移也通过建立附加位移模型进行了补偿，从而有效地提高了系统透明性及稳定性，使触感装置的控制精度更高，抗干扰能力更强。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.