基于MEMS的动作跟踪器的研制

本文针对增强现实中的跟踪定位的需求,采用嵌入式系统设计思想,以新型的微机电惯性器件为核心,利用单片机来构建了一种结构紧凑、低功耗、低成本的通用型惯性测量硬件平台。实现模拟信号处理,并采用多传感器的数据融合算法。最后,通过实验分析,验证了惯性跟踪器的功能。     

四元数小波变换在图像处理中的应用

根据四元小波理论提出了一种新的参数估计方法,用于估计刚体在空间的旋转位置。该方法将四元代数理论与小波变换相结合,推导出基于多分辨率分析的四元小波金字塔。金字塔将二维图像映射到四维空间,其每个层次提供3个相位,利用相位与图像变化之间的线性关系估计空间差距和旋转角度,实现一个自上而下的有效参数估计,从而推广了小波变换的应用。通过物体旋转检测程序对旋转前后的图像进行处理,得到空间变换趋势,证明该理论的可行性。     

基于Hermite方法的机器人任务空间二阶平滑位姿路径构造

机器人任务空间的路径构造一直是研究者们重点关注的对象，更加平滑的路径对于机器人运动尤为关键。提出一种机器人任务空间二阶平滑位姿构造方法。位姿路径分为位置路径与姿态路径，用直线和圆弧来表示基本的位置路径，用四元数来表示姿态路径。根据环境给定的过渡区域，基于Hermite方法分别构造位置和姿态路径的过渡曲线，并设计高效易懂的数值积分算法实现位姿路径长度的计算，然后综合数值积分和二分法查找算法实现给定路径长度的插值计算。最后，在MATLAB软件上进行数值仿真分析，验证了所提算法在机器人任务空间二阶平滑位姿路径构造方面的有效性。     

Interactive mesh deformation using equality-constrained least squares

Mesh deformation techniques that preserve the differential properties have been intensively studied. In this paper, we propose an equality-constrained least squares approach for stably deforming mesh models while approximately preserving mean curvature normals and strictly satisfying other constraints such as positional constraints. We solve the combination of hard and soft constraints by constructing a typical least squares system using QR decomposition. A well-known problem of hard constraints is over-constraints. We show that the equality-constrained least squares approach is useful for resolving such over-constrained situations. In our framework, the rotations of mean curvature normals are treated using the logarithms of unit quaternions in . During deformation, mean curvature normals can be rotated while preserving their magnitudes. In addition, we introduce a new modeling constraints called rigidity constraints and show that rigidity constraints can effectively preserve the shapes of feature regions during deformation. Our framework achieves good performance for interactive deformation of mesh models.     

一种基于四元数算法的双转台五轴后置处理实现

提出一种实现双转台五轴机床后置处理的新方法。在直线运动的坐标变换和空间圆弧插补中引入了四元数算法，使旋转变换计算更加简洁，几何意义更明确，提高了代码的可重用性。通过限制A、C轴角度增量，对直线进行细分，减小了五轴运动非线性误差，提高了运动精度。     

A generic approach of integrating 3D models into virtual manufacturing

Various 3D modeling software has been developed for design and manufacturing.Most of the commercially available software uses native file formats,which may not be able to be read or understood by other...     

Color image watermark decoder by modeling quaternion polar harmonic transform with BKF distribution

It still remains a challenging problem to improve both of the imperceptibility and robustness for the digital image watermarking task. In this study, a color image watermarking scheme is proposed based on quaternion polar harmonic transform (QPHT) with maximum likelihood decoder, which better balances imperceptibility and robustness in a novel fashion. Thanks to the strong robustness of QPHT, the digital watermark is embedded into the QPHT magnitudes using a multiplicative approach. At the receiver, the watermark decoder can be formulated as a problem of weak signal detection, as the QPHT magnitudes are highly non-Gaussian. In view of this, selection of proper models is of great importance to construct a suitable watermark decoder. Further, we validate that the probability density function of Bessel K form suitably models the heavy tail behavior of QPHT magnitudes, and thus the maximum likelihood decoder is developed by modeling QPHT magnitudes with Bessel K form distribution. Experimental results on standard benchmarks demonstrate that the proposed approach provides better imperceptibility and robustness against various kinds of attacks compared to previous state-of-the-art methods.     

基于四元数的Root-MUSIC的双基地MIMO雷达中角度估计算法

该文将四元数理论应用到双基地集中式多输入多输出(MIMO)雷达的角度估计中。文中通过传统数据模型构造四元数矩阵,提出了基于四元数的求根-多重信号分类(Root MUltiple SIgnal Classification, Root-MUSIC)的MIMO雷达中角度估计算法,该算法通过奇异值分解和Root-MUSIC来估计出发射角(Direction Of Departure, DOD)和接收角(Direction Of Arrival, DOA)。该算法的角度估计性能远优于现有文献的方法,并且无需谱峰搜索,复杂度大大降低。仿真结果验证了算法的有效性。