球形机械陀螺全向进动的运动学原理分析

针对现有机械陀螺结构复杂或通常只能单方向进动的不足问题,提出一种自转轴能够按任意方向进动的新型球形陀螺机构,重点对系统运动学原理进行分析和试验。采用球形外壳作为机械陀螺的浮动支撑,以三对全向轮为系统的驱动输入,通过全向轮带动球壳运动设计出球形陀螺机构;根据全向轮与球壳接触的纯滚动假设以及相对运动原理分析系统的运动学特性,建立系统的运动学耦合数学模型;采用物理样机试验对建立的运动学模型进行试验验证,结果表明,无论是在电机驱动下还是人工手拨动球壳,数学模型计算值均能够对实测值进行较好地跟踪。本文研究可为球形机械陀螺的陀螺力矩控制提供理论依据。     

直线电机驱动的全向滚动球形机器人的设计与分析

提出了一种内置稳定平台的新型全向滚动球形机器人装置，由外球壳、内球壳、位于内球壳中的稳定平台、位于内外球壳之间的驱动机构组成。驱动机构为四台直线电机分别在四个空间对称的轮辐上径向移动，改变系统重心位置，驱动球形机器人在平面上全向滚动。内置平台在机器人全向滚动过程中始终保持稳定的姿态，可作为仪器、设备的搭载平台。基于非完整约束和动量矩定理，考虑摩擦力的影响，利用广义欧拉角给出了其二阶控制微分方程组，建立了该球形机器人的运动学和动力学模型，最后结合实例进行了分析和仿真。     

振弦式陀螺频率检测结构设计与振动分析

针对微陀螺高精度和微型化的发展趋势,依据振弦式陀螺的工作原理建立了振弦式陀螺频率检测数学模型;应用ANSYS软件分析了陀螺检测结构参数影响,优化了振弦式陀螺整体结构并建立了振动响应仿真分析。结果表明振弦式陀螺驱动结构振动响应随着驱动力的增大,驱动响应位移量也随之增大,且驱动力与位移量之间具有很好的线性关系,可以很好地控制振弦式陀螺框架驱动力,优化振弦式陀螺结构尺寸,从而验证了振弦式陀螺电磁驱动与频率检测方案模型的可行性。     

摆式陀螺速度检测法全方位快速预定向

为克服国内摆式陀螺寻北仪对初始架设方位要求严格,难以实现全方位寻北的不足,通过对其大偏北角运动规律的分析,提出了一种基于摆速检测的全方位快速预定向方法.运用欧拉动力学方程建立摆式陀螺大偏北角运动方程;运用相平面法分析了其全局运动规律,运用修正的谐波平衡法求得周期摆动的近似解析解;然后根据求得的近似解析解分析了灵敏部摆动速度和摆动周期的变化规律,提出采用最大摆动速度检测法实现全方位预定向,并通过降低陀螺马达转速缩短寻北时间;最后设计了实现方案,并进行了初步试验验证.分析和试验结果表明,该方法能在2 min内实现任意初始架设方位预定向,预定向后灵敏部主轴方位角最大不超过5°.该方法对实现摆式陀螺全方位快速寻北具有重要意义.     

IHI摆式飞剪剪切机构优化设计

飞剪是连续轧制生产线上的重要贵重设备，其结构、控制与调整极其复杂，其运行情况直接影响着轧制生产线的生产效率。作者深入分析了IHI摆式飞剪系统结构组成，并以传动结构简图形式清晰表达了IHI摆式飞剪剪切本体和同步机构之间的协作关系，并以剪切区域内剪刃水平速度与喂料速度误差、摆角误差2个重要性能指标为分目标函数，用加权方式建立了剪切机构优化数学模型。所得优化设计结果，对提高摆式飞剪性能具有重要的价值。     

一种微机械陀螺自激驱动方式的电学模拟

为提高微机械陀螺的检测精度，稳定驱动振动速度幅度，提出了微机械陀螺的自激驱动方式，它能够使驱动振动自动稳定在驱动模态的固有频率上振动，以及保持恒定的驱动振动速度幅度。根据自激驱动电路原理，建立了驱动动力学方程的等效电路模型，用PSPICE软件对电路的工作状况进行了模拟，模拟结果验证了该方法切实可行。     

无理偏摆式平面研磨加工均匀性的数值模拟

基于定偏心平面研磨方式,提出了无理转速比下的偏摆式平面研磨方式.采用矢量方法建立了偏摆式平面研磨加工的运动学方程,对比分析了定偏心和偏摆式驱动下的工件表面磨粒轨迹和磨粒速度场的分布形态,并建立了运动轨迹密度均匀性和材料去除量均匀性的区域划分和统计评价方法.研究表明:偏摆式驱动下的平面研磨轨迹线更加复杂无序,磨粒覆盖面积更大,能更快地获得更均匀的轨迹线分布,且在无理转速比下无明显牛顿环现象,轨迹线的均匀性显著提高;相同转速比时两种驱动方式下磨粒速度场分布形态类型相同,但偏摆式下单颗磨粒的速度大小和速度方向角随时间变化均无明显周期,能获得的速度大于定偏心方式,更快地实现材料去除且无理转速比下的材料去除性更为均匀.最后搭建两种驱动方式的试验平台进行研磨对比试验,通过无理偏摆式加工方式后硅片获得的表面粗糙度Ra最低,且相同时间内的材料去除量最大.     

无驱动结构硅微机械陀螺的原理分析和性能测试

提出了一种利用旋转载体自旋角速度驱动的硅微机械陀螺的结构原理,建立了这种陀螺的数学模型并分析计算了该陀螺的结构动力学参数.理论研究和试验表明,利用旋转载体自身角速度驱动的硅微机械陀螺结构原理正确.通过陀螺性能测试,陀螺输出电压与输入角速度成正比.     

凸轮摆杆剪切机构设计与参数计算

作为高强钢丝生产线上的配套设备,凸轮摆式剪切机构用于实现高强钢丝在线定尺切断,具有剪切力大、动作周期短、定尺精度高等特点。提出凸轮摆式剪切机构设计方案,综合凸轮机构学,从运动学设计角度出发,通过对共轭凸轮外轮廓线的极坐标理论推导,对共轭凸轮运动规律、凸轮轮廓等特征参数进行了设计分析。运用Solid works软件,建立了凸轮摆式剪切机构三维实体模型,并对动力学仿真结果进行了阐释。研究成果为凸轮摆式高强钢丝剪切机的设计奠定了重要的理论依据,同时也为相关新产品的研发提供了有效的设计方法。     

摆式陀螺寻北仪的积分测量方法

提出了摆式陀螺寻北仪双次积分测量方法。在粗寻北阶段采用步进法,通过施加外作用消耗系统原有机械能的方式实现快速寻北。在精寻北阶段采用双次光电积分法,通过对陀螺摆动的一个半周期做积分测量后,利用双次光电积分的方式得到陀螺摆动的平衡位置,然后,通过计算来获得子午面与陀螺轴向之间的夹角。进行了一系列相关实验,结果表明:双次光电积分法有效地改善了JT15试验样机的寻北测量精度,使由于测量周期变化造成的寻北误差减小了10倍以上。本方案缩短了摆式陀螺寻北仪的寻北测量时间,提高了寻北测量精度,满足了工程实用的精度和快速性要求。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

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.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

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....     

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.