On inverting singular kinematics and geodesic trajectory generation for robot manipulators

In this paper, a new method is proposed of solving the inverse kinematic problem for robot manipulators whose kinematics are allowed to possess singularities. The method is based upon the so-called generalized Newton algorithm, introduced by S. Smale, and can be adopted to both nonredundant and redundant kinematics. Moreover, given a pair of points in the external space of a manipulator, the method is capable of generating a minimum-length trajectory joining the points (a geodesic), in particular a straight-line trajectory. Results of representative computer experiments, including those with the PUMA 560 kinematics, are reported in order to illustrate the performance of the method.     

基于B样条的改进型Harris角点检测算法*

在研究Harris角点检测算法时发现由于该算法采用高斯低通滤波进行平滑,因而对一些图像进行角点提取时,存在角点信息丢失和位置偏移等现象,而B样条函数可以收敛于高斯函数,并具有良好的逼近能力和紧支性等一些优秀的性质,从而基于B样条函数提出了一种改进的Harris角点提取方法。实验表明,该方法对提取角点非常有效。     

燃烧模型方程组柯西问题的整体光滑解及其奇性形成

本文考虑燃烧模型方程组的柯西问题整体光滑解之存在性和解的毒性形成。     

一种用于机器人视觉系统的码链曲线角点寻求算法

本文描述了一种在平面码链曲线上检测尖锐角点的方法。对如何测量角点凸性进行了详细介绍。通过例子说明了该算法的实效性。最后,将计算法应用于机器人视觉系统,给出了仿真结果。     

On singularities of flat affine systems with n states and n−1 controls

We study the set of intrinsic singularities of flat affine systems with n?1 controls and n states using the notion of Lie‐Bäcklund atlas, previously introduced by the authors. For this purpose, we prove two easily computable sufficient conditions to construct flat outputs as a set of independent first integrals of distributions of vector fields: the first one in a generic case, namely, in a neighborhood of a point where the n?1 control vector fields are independent and the second one at a degenerate point where p?1 control vector fields are dependent of the n?p others, with p>1. After introducing the Γ‐accessibility rank condition, we show that the set of intrinsic singularities includes the set of points where the system does not satisfy this rank condition and is included in the set where a distribution of vector fields introduced in the generic case is singular. We conclude this analysis by three examples of apparent singularities of flat systems in generic and nongeneric degenerate cases.     

基于双目视觉的三维测量技术研究

本文对基于双目视觉的三维测量技术研究进行了深入挖掘,主要包括摄像机模型、双目相机的标定、图像校正、立体匹配等。同时借鉴机器学习的分类思想,将角点提取转化为二分类问题,利用随机森林算法来实现角点提取,再利用随机森林的预测结果来实现亚像素级角点提取。该方法相对于传统三维测量中的角点提取算法具有更好的自动化性能,能避免角点集群现象,能实现较高精度的亚像素级角点提取,获得更高精度的二维像素坐标。从而利用高精度的二维像素坐标来获得点的三维世界坐标,这也是基于双目视觉的三维测量技术的基础与核心。     

基于直线逼近的图形角点检测技术研究

拐点是数字图像中的一个重要信息载体,本文针对具有类直线边界的图像提出一种新的拐点检测算法。该算法并非通过在连续空间内选择支撑区域计算每个点的特征值来选择角点,而是在针对特定图形特征,首先通过Freeman链码提取图像边缘;然后通过图像支撑点和连接点的概念过滤掉一些明显不为拐点的像素;最后用直线逐段来代替图像边缘曲线,而替代直线的端点则构成了图像的拐点。     

MT: A Mathematica package to compute convolutions

We introduce the Mathematica package MT which can be used to compute, both analytically and numerically, convolutions involving harmonic polylogarithms, polynomials or generalized functions. As applications contributions to next-to-next-to-next-to leading order Higgs boson production and the Drell–Yan process are discussed.     

Embedded desingularization of toric varieties

We present a new method to achieve an embedded desingularization of a toric variety.Let W be a regular toric variety defined by a fan Σ and X⊂W be a toric embedding. We construct a finite sequence of combinatorial blowing-ups such that the final strict transforms X^′⊂W^′ are regular and X^′ has normal crossing with the exceptional divisor.