基于图像传感器的圆心定位技术实用化研究

基于图像传感器的圆心定位技术适用于多种非接触式测量系统。这类技术对测量环境的要求比较苛刻。以提高圆心定位技术的适应能力为目的,提出了针对抗干扰、边界识别和圆心拟合等测量过程关键技术环节的实用化改进方案,综合运用了时间递推滤波、深度优先搜索算法和迭代最小二乘法等方法。改进后的测量系统具有良好的稳定性和适应性,在地铁隧道形变监测项目中成功投入使用。     

Exact optimal solution for a class of dual control problems

This paper considers a discrete-time stochastic optimal control problem for which only measurement equation is partially observed with unknown constant parameters taking value in a finite set of stochastic systems. Because of the fact that the cost-to-go function at each stage contains variance and the non-separability of the variance is so complicated that the dynamic programming cannot be successfully applied, the optimal solution has not been found. In this paper, a new approach to the optimal solution is proposed by embedding the original non-separable problem into a separable auxiliary problem. The theoretical condition on which the optimal solution of the original problem can be attained from a set of solutions of the auxiliary problem is established. In addition, the optimality of the interchanging algorithm is proved and the analytical solution of the optimal control is also obtained. The performance of this controller is illustrated with a simple example.     

ADRC Law of Spacecraft Rendezvous and Docking in Final Approach Phase

This article addresses the high-precision coordinated control problem of spacecraft autonomous rendezvous and docking, which couple the relative position and attitude in the final approach phase. The coupled dynamics equations of the tracking-target spacecrafts is derived by using dual quaternions. Then, a cascade Active Disturbance Rejection Controller is proposed, by which the extended state observer and nonlinear error feedback law is designed, the virtual value on which the actual control volume tracking is calculated to ensure the finite time convergence of the relative position and attitude tracking errors in spite of parametric uncertainties and external disturbances. Finally, numerical simulations are performed to demonstrate that the proposed approaches, which can avoid the coupling effect and restrain the interference, can track the target spacecraft in a relatively short period of time, and the control precision can satisfy the requirements of docking.     

一种融合Hough变换和ASM定位瞳孔中心点方法

特征点的准确定位是机器视觉和模式识别的关键技术之一.主动形状模型(ASM)是一种传统的图像特征点定位算法,具有较高的精确性和鲁棒性.为了提高ASM人脸瞳孔特征点定位的精确度,提出了使用Hough变换方法来改进瞳孔特征点的定位.通过ASM算法,初步定位出瞳孔特征点,并使用Sobel算子对图像进行边缘检测,然后在人眼位置选择一个合适的窗口使用Hough圆检测,找出精确瞳孔点相对于ASM初步定位瞳孔点的偏移量.在实验室采集的人脸图像上的对比实验表明,该方法能够显著的改善ASM人眼瞳孔特征点定位准确性.由于使用了初定位进行了搜索范围的限制,计算量也得到了有效的控制.     

基于笔画曲率特征的笔迹鉴别方法

现有的手写汉字脱机笔迹鉴别方法存在只能针对特定字符或需要大量样本字符等问题,为此提出一种基于笔画曲率特征的笔迹鉴别方法。首先运用数学形态学对采集的笔迹图像进行预处理,在横、竖、撇、捺四个方向提取具有代表性的笔画骨架,然后对笔画骨架进行圆的重构,提取四个方向笔画圆的曲率作为特征值组成笔迹特征矩,根据待鉴别的笔迹特征矩与数据库中笔迹特征矩向量夹角相似性度量结果对样本做出判断。实验结果表明该文方法对于待鉴别样本字符的内容没有要求,样本字符数量要求低、应用范围广、鲁棒性强。     

A globally and quadratically convergent primal–dual augmented Lagrangian algorithm for equality constrained optimization

We present a primal–dual augmented Lagrangian method to solve an equality constrained minimization problem. This is a Newton-like method applied to a perturbation of the optimality system that follows from a reformulation of the initial problem by introducing an augmented Lagrangian function. An important aspect of this approach is that, by a choice of suitable updating rules of parameters, the algorithm reduces to a regularized Newton method applied to a sequence of optimality systems. The global convergence is proved under mild assumptions. An asymptotic analysis is also presented and quadratic convergence is proved under standard regularity assumptions. Some numerical results show that the method is very efficient and robust.     

Circular polarized dual‐band antenna for WLAN/Wi‐MAX application

A novel square ring printed antenna has been suggested for dual‐band circular polarization (CP). The geometry contains a square patch and a square ring structure for dual‐band operation. Circular polarization is achieved using triangular cut at the boundary and right angle bend with inner perturbation. The suggested antenna is excited from the lower layer through electromagnetic (EM) coupling technique. The antenna shows good impedance bandwidths of 90 MHz (2.43‐2.52 GHz) and 800 MHz (5.7‐6.5 GHz, respectively. The antenna shows 3 dB axial ratio bandwidth of 20 MHz at lower band and 120 MHz at upper band with improved gain > 6 dBi. The simulated and measured results are well agreed with each other. The antenna is promising wideband operation at the upper band. This antenna was implemented on fiberglass reinforcement laminated Arlon substrate with dielectric constant (?_r = 2.55), and the overall physical dimension of 30 × 30 × 3.048 mm³. The designed antenna can be extensibly applicable in WLAN/Wi‐MAX communication. The presented antenna is designed using hyperlynx IE3D and the simulated results are presented.     

Tri‐band composite cylindrical dielectric resonator antenna with hybrid mode excitation and cross‐polarization suppression

This communication investigates composite cylindrical dielectric resonator antenna (CDRA) for various wireless applications. Three important features of proposed antenna design are (i) realization of two different hybrid modes, that is, HEM_11δ and HEM_12δ mode in CDRA with the help of modified annular ring printed line (work as both magnetic dipole and electric dipole), both the hybrid modes support broadside radiation characteristics (ii) suppression of HEM_21δ mode, in order to reduce the cross‐polarization level in H‐plane of other hybrid modes (HEM_11δ and HEM_12δ mode) by an amount of 8‐10 dB (iii) creation of triple‐band attribute using the concept of composite antenna. The proposed antenna design has been fabricated and practically tested. Simulated outcomes show good agreement with measured outcomes. It works in three frequency bands, that is, 2.25‐2.79 GHz, 3.1‐4.0 GHz, and 5.05‐5.6 GHz. The designed antenna structure is appropriate for WLAN and WiMAX applications.     

基于Hough变换与最小二乘拟合的香烟小包拉线错牙检测方法

针对小盒香烟包装生产过程中经常出现外包装透明薄膜上没有拉线或拉线错牙等现象,提出一种基于图像处理技术的检测方法。首先,对烟包拉线图像进行边缘检测,获得拉线的轮廓;其次,利用Hough变换检测小盒拉线的上下边缘;当Hough变换无法完全找到拉线的上下边界时,采用最小二乘算法对左右两侧拉线弧进行圆拟合,最后根据计算出的拉线宽度或两圆心的垂直距离判断拉线是否错牙并计算出拉线错牙偏移量。实验结果表明所提方法能有效地检测出烟包拉线的错牙程度,且具有较好的鲁棒性和有效性。     

PLC双输出控制在工业现场中的应用

随着科技的发展,PLC因其简洁、高效而被广泛的应用于各行各业中.但传统PLC控制系统的设计,并没有考虑到PLC故障时对系统所造成的影响.对PLC系统采用双输出脉冲触发控制方式,可以很好的解决这一问题.