基于最小平方中值定理的立体视觉里程计

提出了一种基于最小平方中值定理（LMedS）的立体视觉里程计方法。利用图像中尺度不变的SIFT特征点作为路标,基于KD树的最邻近点搜索算法来实现左右图像对特征点的匹配和前后帧间特征点跟踪。通过特征点的三维重建,基于最小平方中值定理估计出机器人的运动距离和方向信息。实验表明该方法在不同图像间匹配、三维路标跟踪和机器人运动估计中具有很强的鲁棒性。     

Automatic Construction and Verification of Isotopy Invariants

We extend our previous study of the automatic construction of isomorphic classification theorems for algebraic domains by considering the isotopy equivalence relation. Isotopism is an important generalisation of isomorphism, and is studied by mathematicians in domains such as loop theory. This extension was not straightforward, and we had to solve two major technical problems, namely, generating and verifying isotopy invariants. Concentrating on the domain of loop theory, we have developed three novel techniques for generating isotopic invariants, by using the notion of universal identities and by using constructions based on subblocks. In addition, given the complexity of the theorems that verify that a conjunction of the invariants form an isotopy class, we have developed ways of simplifying the problem of proving these theorems. Our techniques employ an interplay of computer algebra, model generation, theorem proving, and satisfiability-solving methods. To demonstrate the power of the approach, we generate isotopic classification theorems for loops of size 6 and 7, which extend the previously known enumeration results. This work was previously beyond the capabilities of automated reasoning techniques. The author’s work was supported by EPSRC MathFIT grant GR/S31099.     

具有饱和状态反馈离散时滞系统的渐近稳定性

讨论具有饱和状态反馈的离散时滞线性系统的渐近稳定性问题. 给出了在一定假设下, 判断系统全局渐近稳定和局部渐近稳定的充分条件, 并通过数值算例验证了所给出的条件是有效的.     

Global dynamics for non-autonomous reaction-diffusion neural networks with time-varying delays

In this paper, a class of non-autonomous reaction-diffusion neural networks with time-varying delays is considered. Novel methods to study the global dynamical behavior of these systems are proposed. Employing the properties of diffusion operator and the method of delayed inequalities analysis, we investigate global exponential stability, positive invariant sets and global attracting sets of the neural networks under consideration. Furthermore, conditions sufficient for the existence and uniqueness of periodic attractors for periodic neural networks are derived and the existence range of the attractors is estimated. Finally two examples are given to demonstrate the effectiveness of these results.     

Invariant and attracting sets of impulsive delay difference equations with continuous variables

The aim of this paper is to study the invariant and attracting sets of impulsive delay difference equations with continuous variables. Some criteria for the invariant and attracting sets are obtained by using the decomposition approach and delay difference inequalities with impulsive initial conditions.     

人脸检测技术的研究进展

近年来由于人脸检测技术在身份验证、视频监控等领域日益广泛的应用,对于人脸检测的研究越来越受到人们的重视。该文对各发展阶段的方法进行介绍比较,指出其优劣性。     

一种改进的鲁棒约束预测控制器的综合设计方法

针对多包描述的不确定系统,提出一种新的鲁棒约束预测控制器.高线设计多包系统worst-case情况下性能最优的不变集,在线求解多包系统无穷时域性能指标的rain-max优化问题.设计方法采用了时变的终端约束集,扩大了初始可行域,并能获得较优的控制性能.仿真结果验证了该方法的有效性.     

基于SIFT特征的合成孔径雷达景象匹配方法

根据合成孔径雷达图像的特点,提出一种基于SIFT特征的合成孔径雷达(SAR)景象匹配的方法。首先利用改进的特征描述符初步提取实时图与参考图的SIFT 关键点;然后利用距离比和RANSAC算法去除错配,匹配出可靠的同名点对;最后计算反映实时图和参考图之间变换关系的转换参数,完成景象匹配。实验结果表明,本方法快速实用,有较强的有效性和鲁棒性。     

基于小波不变矩的医学图像配准技术研究

图像配准是对取自不同时间、不同传感器或不同视角的同一场景的两幅图像或者多幅图像匹配的过程,是图像融合、目标探测识别和计算机视觉等技术的重要基础,主要用于消除来自不同传感器的图像中目标的位置差异.提出了一种新图像匹配算法,新算法以提升格式小波变换为基础,利用图像多级小波分解后近似分量的轮廓相似性进行图像的快速配准.实验结果表明,新方法高效精确.     

Fault tolerant control for singular systems with actuator saturation and nonlinear perturbation

In this paper, the problem of robust fault tolerant control for a class of singular systems subject to both time-varying state-dependent nonlinear perturbation and actuator saturation is investigated. A sufficient condition for the existence of a fixed-gain controller is first proposed which guarantees the regularity, impulse-free and stability of the closed-loop system under all possible faults. An optimization problem with LMI constraints is formulated to determine the largest contractively invariant ellipsoid. An adaptive fault tolerant controller is then developed to compensate for the failure effects on the system by estimating the fault and updating the design parameter matrices online. Both of these two controllers are in the form of a saturation avoidance feedback with the advantage of relatively small actuator capacities compared with the high gain counterpart. An example is included to illustrate the proposed procedures and their effectiveness.