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。     

便携式手术机器人主手附加力位移补偿方法研究

采用拉格朗日方程和Stribeck摩擦模型,根据便携式手术机器人主手的杆件重力、各关节摩擦力、惯性力对术者真实力感知的影响,建立了含关节摩擦力的动力学模型。基于机器人主手动力学模型,分别建立重力、摩擦力和惯性力三项的补偿模型,通过分析机器人主手力补偿反馈和附加位移的产生原因及补偿原理,提出了相应的补偿反馈力和附加位移补偿方法。通过对初步研究结果进行对比试验,验证该力补偿控制方法可用以平衡主手因自身所带的重力、关节摩擦力和惯性力产生的影响,最终实现术者真实的力感知,提高手术操作精准性。     

新型深海作业船体波浪补偿预控系统研究

传统的深海作业船体波浪补偿方法效率较低,且使用范围具有较大的局限性。针对传统方法的不足,提出并设计了一种新型主动波浪补偿预控系统。结合波浪预测装置在预测周期里推算出整个控制周期内起重吊点的位移,在随后的补偿周期里利用补偿动作装置对该位移作出全额补偿。随后进入下一个控制周期,周而复始并贯穿于整个工作阶段。通过理论计算分析得出本系统可较大程度上减小因波浪起伏而导致的钢绳附加应力,能较好的进行深海作业船体波浪补偿,为系统的研究提供了思路和参考。     

基于联合仿真技术的深海采矿升沉补偿装置控制系统的研究

该文联合虚拟样机技术和控制系统仿真技术对深海采矿升沉补偿系统进行了设计研究,建立了基于液压动力源的升沉补偿系统采矿船多刚体机械动力学模型,并针对该模型设计了模糊自整定PID控制器。联合仿真研究结果表明,模糊自整定PID控制策略能很好地对升沉补偿装置进行有效的位移补偿控制,补偿率可达到40%~45%,从而提高了深海采矿系统的稳定性。     

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.     

片层体积无损测量装置误差分析与补偿研究

为了提高片层体积无损测量装置实验精度,建立了实验装置误差模型并对误差补偿进行研究。运用多体系统理论的齐次矩阵变换在平口钳、运动平台、夹具上建立各自坐标系,对实验平台各相邻构件几何误差进行系统分析,并根据误差传递关系,建立了实验装置综合误差模型。基于点在空间坐标系下矢量表达的补偿方法,通过测量辨析,完成了对误差补偿模型参数的确定。通过补偿验证,实验装置精度获得了较大提升。表明该方法能有效地对实验装置误差进行补偿,为实验数据采集提供精度保证。     

望远镜面型误差实时测量与补偿研究

为实现大型射电望远镜反射面面型误差实时测量与解耦补偿，满足大口径、高频率射电望远镜对高精度反射面的需求，对望远镜面型误差实时测量与补偿进行了研究。设计了一种基于6SPS型并联机构的面板相对位姿传感器，通过建立数学模型对测量原理进行分析。针对现有主动面调整装置引起的面板误差耦合问题，提出一种6PSS构型调整装置，对安装方式、调整原理进行分析，并建立运动学模型。将面板相对位姿传感器与主动面调整装置相结合，组成反射面精度实时测量与误差解耦补偿系统，建立系统数学模型，通过数值算例验证可行性。     

用于异形孔精密加工的超磁致伸缩构件的线性化迟滞建模

根据超磁致伸缩构件精密加工异形孔刀具轨迹的特点,采用纯延时环节串联线性化模型,建立其在高频驱动下驱动电流与输出微位移的迟滞非线性动态模型.通过一定频率下驱动电流与输出位移的相关辨识,获得系统纯延时环节的补偿参数,并建立了驱动电流与无相位差输出位移的线性化模型.当实时控制时,通过迟滞非线性模型的直接逆模型补偿,使位移输出与异形孔的理想刀具轨迹一致.实验验证表明,直接逆模型的最大开环控制误差为2.7 μm,最大相对误差为10％.进一步对构件进行微位移反馈闭环控制,实验误差最大值为1.2 μm,最大相对误差为7％,提高了系统的控制精度.     

电致伸缩微位移装置的高精度控制方法研究

针对电致伸缩微位移高精度控制的需求，研究了基于非线性迟滞模型的前馈补偿与反馈技术相结合的控制方法，对电致伸缩微位移装置进行控制，取得良好的控制效果。将其应用于柔性工作台控制系统中，系统在跟踪正弦曲线时，跟踪误差小于5nm。     

浮式钻井平台被动升沉补偿装置设计

设计了浮式钻井平台被动式升沉补偿装置,进行了系统的受力分析,建立了AMESim仿真模型,研究了负载和蓄能器体积变化对补偿效果的影响.仿真结果表明被动式升沉补偿装置具有一定的补偿效果,但系统蓄能器体积较大,补偿存在滞后现象.采用相似原理建立了实验装置,进行了不同升沉幅值的实验研究,实验数据和仿真曲线符合较好,表明该模拟实验台设计合理,建立的仿真模型准确.     

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...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

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.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.