51 resultados para Branch-and-bound algorithm
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本文提出了一种结构化环境下,基于立体视觉的机器人楼梯识别算法,并将算法该应到自主移动机器人上。该算法首先利用二维图像分析的方法搜索楼梯的疑似区域;进而利用立体视觉对各个疑似区域进行精确三维重建,结合三维信息重构楼梯平面,排除虚假疑似楼梯区域;最后判定机器人和楼梯的相对位姿关系,引导机器人爬楼梯。最终我们将该算法应用到了自主移动机器人上,通过在各种光照条件下的实验,进一步验证了该算法的准确性和快速性。
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给出了自主移动机器人定位的两种算法:解析算法和数值算法。解析法公式较以往的简洁。数值算法结合解析法和高斯-牛顿算法,不仅能避免因初值选取不合理而导致求解过程发散的问题,而且能提高运算精度和速度,通过对两种算法的计算机仿真,表明了解析算法具有运算速度快,而数值算法精度高的特点。其结果已用于自主移动机器人的研制中。
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本文的研究内容是围绕国家“973”计划支持项目“基于智能制造单元的可重构装配生产线基础理论与实现方法研究”展开的。本研究以汽车减速箱装配生产线为实际背景,主要工作由四部分组成:对汽车减速箱的产品结构、装配工艺特征深入分析的基础上,提出了主干线和装配模块相结合的组织结构建模方法;利用网络法进行分析装配系统的三个重构过程,提出了适用于增容性、鲁棒性、适应新产品重构的优化算法;建立了基于多Agent系统的混合控制体系结构,利用JADE平台进行具体软件编程,实现了可重构装配生产线的控制系统;最后将组织结构建模、控制结构建模、重构优化算法有效的结合成统一整体,通过对Agent之间协商机制的研究,最终实现了可重构装配系统的实时重构、调度和控制,初步形成基于智能制造单元的汽车减速箱可重构装配系统的基本理论框架和方法体系。首先对汽车减速箱的产品结构、装配工艺特征进行了深入分析,从而形成了基于功能对象的产品族划分方法。在此基础上,根据模块化的设计思想,提出了主干线和装配模块相结合的可重构装配系统的开放式组织结构。通过引入缓冲区和多功能工作站,使得装配系统具有能力柔性、鲁棒性、功能扩展能力等特点,并能够通过模块的局部调整快速响应市场的需求。利用随机过程的基本原理,在建立缓冲区状态数学模型的基础上,以缓冲区被充满概率最小化为目标,通过递进算法确定缓冲区容量。讨论了可重构装配系统的两个规划问题:负荷平衡和多品种排序。阐述了混合模型产品的装配任务优先图和优先矩阵的合并,建立负荷平衡问题的数学模型,并总结了目前存在的求解方法。在归纳投产排序的优化模型和目标函数的基础上,介绍了生产比倒数法、试探法、循环改进法等优化方法。重构过程的优化是可重构装配系统研究的一个重要方面。利用网络法的基本原理,针对扩大生产能力、设备故障和新产品到达的三种系统重构要求,给出了相应的重构算法。通过装配操作向多功能工作站的转移以实现装配系统的增容;以工期延长最短为优化目标,利用网络法中的组织优化原则实现系统的鲁棒性重构;以最大候选原则的基本原理为基础,提出了基于固定设备约束的重构算法用于系统适应新产品的重构。在分析传统控制系统体系结构的基础上,根据可重构装配系统组织结构的特征,提出了基于多Agent系统的混合控制体系结构,它结合了递阶结构和分布式控制的优点,使得更有利于实现可重构装配系统的实时控制、调度和重构。为了对Agent进行建模和实现,在遵守FIPA规范的前提下,以汽车减速箱装配系统为背景,利用JADE开发平台,进行了各层Agent的实例开发,包括Agent属性描述、行为定义、通讯机制以及交互界面设计和Agent具体功能的编程实现。可重构装配系统重构过程的实现机理体现为多Agent之间的有效协商。在对现有Agent协商模型深入分析的基础上,针对鲁棒性、增容性、适应新产品的装配系统三个重构问题,提出了多Agent系统的协商机制,主要包括协商问题的形式化描述、协商模型、协商策略,结合相应的重构算法实现装配系统的重构。给出了Agent协商过程中存在的主要冲突和消解方法。通过多Agent系统协商实现可重构装配系统重构、调度和控制,充分体现了控制系统集中规划与分布式求解相结合的优点。
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水下环境的复杂性以及自身模型的不确定性,给水下机器人的控制带来很大困难。针对水下机器人的特点和控制方面所存在的问题,提出了基于预测 校正控制策略的水下机器人神经网络自适应逆控制结构及训练算法。通过在线辨识系统的前向模型,估计出系统的Jacobian矩阵,然后采用预报误差法实现控制器的自适应。同时,为了提高系统对于外扰的鲁棒性,在伪线性回归算法的基础上,在评价函数中引入微分项。理论分析和仿真结果表明,与原来的算法相比,微分项的引入改善了系统对于外扰的鲁棒性和动态性能。
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本文针对基于Agent的分布协作式多机器人装配系统——DAMAS的特点,在原有工作的基础上,提出了网络环境下基于Agent的路径规划思想,重新定义Agent各功能模块的内容,建立系统中的通讯机制.同时,介绍了系统进行路径规划的工作过程,给出了路径规划器的规划算法
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介绍了一种摄像机云台自动跟踪控制系统 ,该系统用来实现遥控机械手主从操作时摄像机自动跟踪从手末端夹钳的运动以辅助操作员进行遥控操作 ;介绍了系统的组成、工作原理及控制算法 ;实验结果验证了算法的正确性和控制系统的可行性。
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不可信赖的算法和系统不是人工智能的初衷,准确率较高的不可信赖系统如果有相当水平的专家的协同作业,有可能提高工作效率;但在完全自动化的条件下或者在与其配合工作的人不是非常可信赖的情况下,不可信赖系统则将丧失使用与存在价值.相反,可信赖系统却能够出色地工作,达到并长期保持制作它的群体专家的水平.可信赖系统不仅在效率方面而且将在质量方面体现人工智能的优越性和不可替代性,因此将是推动知识经济的发动机.已经证明,一个不可信赖的算法,最终必然破坏系统中其他可信赖算法的可信赖性,应该予以扬弃.实现可信赖算法和系统的工作量和难度都大大增加.可信赖算法本质上只适用于可界定、可判定的类.实现基于类与OOP理论的若干可界定领域的可信赖算法与系统在实践上有确切的用途.已经证明,若干可信赖算法的集成仍然是可信赖的;因此通过不断地继承和集成能够逼近最终的目标。
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本文首先介绍了文献[1]给出的基于空值完全语义的五值逻辑(5VL),定义了基于5VL的比较运算和逻辑运算的运算规则,并以此为基础结出了一般条件表达式下选择运算的处理策略和实现算法。
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讨论了非线性未建模不确定系统的自适应镇定问题。通过边界层次分析的方法,提出一和种简单的间接自适应控制方法。该方法克服了现有非线性自适应控制方法容易产生过渡控制的缺点。
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本文叙述一种改进型HAMMING网在印刷汉字文本识别实用系统中作为粗分类的应用.给出了以3755印刷汉字为多模式分类对象的神经网络分类器的结构及其相应的算法.该方法在微型机上用软件仿真得以实现.取得令人满意的结果.
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针对Bzier曲线间最近距离计算问题,提出一种简捷、可靠的计算方法.该方法以Bernstein多项式算术运算为工具,建立Bzier曲线间最近距离的计算模型;然后充分利用Bzier曲面的凸包性质和de Casteljau分割算法进行求解.该方法几何意义明确,能有效地避免迭代初始值的选择和非线性方程组的求解,并可进一步推广应用于计算Bzier曲线/曲面间的最近距离.实验结果表明,该方法简捷、可靠且容易实现,与Newton-Raphson方法的融合可进一步提高该方法的运行速度.
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建立三角面片之间拓扑关系是提高分层切片效率的关键因素之一,提出基于标准模板库set容器的拓扑关系重建算法及快速切片算法,有效地去除了STL文件大量冗余数据,简化了数据的存储,该算法每一个三角面片在每一切平面内只求一次交点,切片完成后可直接得到封闭轮廓环,以减少在切片过程中对三角面片的遍历次数、排序次数及求交点计算量,简化了轮廓环的构造过程,从而有效地提高了算法的效率。
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介绍了Zernike矩及基于Zernike矩的图像亚像素边缘检测原理,针对Ghosal提出的基于Zernike矩的亚像素图像边缘检测算法检测出的图像存在边缘较粗及边缘亚像素定位精度低等不足,提出了一种改进算法.推导了7×7 Zernike矩模板系数,提出一种新的边缘判断依据.改进的算法能较好检测图像边缘并实现了较高的边缘定位.最后,设计了3组不同的实验.实验结果同Canny算子及Ghosal算法相比,证明了改进算法的优越性.
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With the development of oil/gas seismic exploration, seismic survey for fracture/porosity type reservoir is becoming more and more important. As for China, since it has over 60% store of low porosity and low permeability oil/gas reservoir, it’s more urgent to validly describe fracture/porosity type oil/gas trap and proposing the related, developed seismic technique. To achieve mapping fracture/porosity region and its development status, it demands profound understanding of seismic wave propagation discipline in complex fractured/pored media. Meanwhile, it has profound scientific significance and applied worth to study forward modeling of fracture/porosity type media and pre-stacked reverse time migration. Especially, pre-stacked reverse-time migration is the lead edge technique in the field of seismology and seismic exploration. In this paper, the author has summarized the meaning, history and the present state of numerical simulation of seismic propagation in fractured/pored media and seismic exploration of fractured/pored reservoirs. Extensive Dilatancy Anisotropy (EDA) model is selected as media object in this work. As to forward modeling, due to local limitation of solving spatial partial derivative when using finite-difference and finite-element method, the author turns to pseudo-spectral method (PSM), which is based on the global characteristic of Fourier transform to simulate three-component elastic wave-field. Artifact boundary effect reduction and simulation algorithm stability are also discussed in the work. The author has completed successfully forward modeling coding of elastic wave-field and numerical simulation of two-dimensional and three-dimensional EDA models with different symmetric axis. Seismic dynamic and kinematical properties of EDA media are analyzed from time slices and seismic records of wave propagation. As to pre-stacked reverse-time migration for elastic wave-field in fractured/pored media, based on the successful experience in forward modeling results with PSM, the author has studied pre-stacked reverse-time depth-domain migration technique using PSM of elastic wave-field in two dimensional EDA media induced by preferred fracture/pore distribution. At the same time, different image conditions will bring up what kind of migration result is detailed in this paper. The author has worded out software for pre-stacked reverse-time depth-domain migration of elastic wave-field in EDA media. After migration processing of a series of seismic shot gathers, influences to migration from different isotropic and anisotropy models are described in the paper. In summary, following creative research achievements are obtained: Realizing two-dimensional and three-dimensional elastic wave-field modeling for fractured/pored media and related software has been completed. Proposed pre-stacked reverse-time depth-domain migration technique using PSM of elastic wave-field. Through analysis of the seismic dynamic and kinematical properties of EDA media, the author made a conclusion that collection of multi-component seismic data can provide important data basis for locating and describing the fracture/pore regions and their magnitudes and the preferred directions. Pre-stacked reverse-time depth-domain migration technique has the ability to reconstruct complex geological object with steep formations and tilt fracture distribution. Neglecting seismic anisotropy induced by the preferred fracture/pore distribution, will lead to the disastrous imaging results.
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Geophysical inversion is a theory that transforms the observation data into corresponding geophysical models. The goal of seismic inversion is not only wave velocity models, but also the fine structures and dynamic process of interior of the earth, expanding to more parameters such as density, aeolotropism, viscosity and so on. As is known to all, Inversion theory is divided to linear and non-linear inversion theories. In rencent 40 years linear inversion theory has formed into a complete and systematic theory and found extensive applications in practice. While there are still many urgent problems to be solved in non-linear inversion theory and practice. Based on wave equation, this dissertation has been mainly involved in the theoretical research of several non-linear inversion methods: waveform inversion, traveltime inversion and the joint inversion about two methods. The objective of gradient waveform inversion is to find a geologic model, thus synthetic seismograms generated by this geologic model are best fitted to observed seismograms. Contrasting with other inverse methods, waveform inversion uses all characteristics of waveform and has high resolution capacity. But waveform inversion is an interface by interface method. An artificial parameter limit should be provided in each inversion iteration. In addition, waveform information will tend to get stuck in local minima if the starting model is too far from the actual model. Based on velocity scanning in traditional seismic data processing, a layer-by-layer waveform inversion method is developed in this dissertation to deal with weaknesses of waveform inversion. Wave equation is used to calculate the traveltime and derivative (perturbation of traveltime with respect to velocity) in wave-equation traveltime inversion (WT). Unlike traditional ray-based travetime inversion, WT has many advantages. No ray tracing or traveltime picking and no high frequency assumption is necessary and good result can be got while starting model is far from real model. But, comparing with waveform inversion, WT has low resolution. Waveform inversion and WT have complementary advantages and similar algorithm, which proves that the joint inversion is a better inversion method. And another key point which this dissertation emphasizes is how to give fullest play to their complementary advantages on the premise of no increase of storage spaces and amount of calculation. Numerical tests are implemented to prove the feasibility of inversion methods mentioned above in this dissertation. Especially for gradient waveform inversion, field data are inversed. This field data are acquired by our group in Wali park and Shunyi district. Real data processing shows there are many problems for waveform inversion to deal with real data. The matching of synthetic seismograms with observed seismograms and noise cancellation are two primary problems. In conclusion, on the foundation of the former experiences, this dissertation has implemented waveform inversions on the basis of acoustic wave equation and elastic wave equation, traveltime inversion on the basis of acoustic wave equation and traditional combined waveform traveltime inversion. Besides the traditional analysis of inversion theory, there are two innovations: layer by layer inversion of seimic reflection data inversion and rapid method for acoustic wave-equation joint inversion.