Optimal Deployment of Mobile Sensors for Target Tracking in 2D and 3D Spaces

This paper proposes a control strategy to autonomously deploy optimal placements of range-only mobile sensors in 2D and 3D spaces. Based on artificial potential approaches, the control strategy is designed to minimize the intersensor and external potentials. The inter-sensor potential is the objective function for optimal sensor placements. A placement is optimal when the inter-sensor potential is minimized. The external potential is introduced to fulfill constraints on sensor trajectories. Since artificial potential approaches can handle various issues such as obstacle avoidance and collision avoidance among sensors, the proposed control strategy provides a flexible solution to practical autonomous optimal sensor deployment. The control strategy is applied to several optimal sensor deployment problems in 2D and 3D spaces. Simulation results illustrate how the proposed control strategy can improve target tracking performance.      

基于节点重部署的水下传感器网络三维栅栏覆盖

水下传感器网络是近年的研究热点,如何高效实现三维栅栏覆盖,仍是一个开放的课题.把三维栅栏覆盖转化为二维区域覆盖空洞修补,针对栅栏平面上的覆盖空洞,设计穿过空洞质心的垂直修补线段.提出了基于节点重部署的能量高效的三维栅栏构建算法(Bmon),针对栅栏平面上的覆盖空洞,选择移动能耗最小的节点移动到空洞的垂直修补线段上,修补覆盖空洞,实现三维栅栏覆盖.仿真结果验证了该算法的有效性.该研究对三维覆盖研究有一定的理论和借鉴意义.     

仿生湿吸二维微力传感器设计与试验研究

设计了一种L型的二维微力传感器,该二维微力传感器采用悬臂梁式结构。在弹性力学和材料力学基础上,利用Solidworks三维建模软件和ANSYS仿真软件对传感器分别进行模型建立和有限元应变分析。对该二维微力传感器的实体进行标定,得出了力和输出电压之间的关系。然后,在设计与分析二维微力传感器的基础上,研制了二维微力传感器阵列测试系统。最后,在测试系统实施了不同预压力下的湿吸力测试试验,验证了传感器和系统的可靠性。     

An automatic 2D to 3D video conversion approach based on RGB-D images

3D movies/videos have become increasingly popular in the market; however, they are usually produced by professionals. This paper presents a new technique for the automatic conversion of 2D to 3D video based on RGB-D sensors, which can be easily conducted by ordinary users. To generate a 3D image, one approach is to combine the original 2D color image and its corresponding depth map together to perform depth image-based rendering (DIBR). An RGB-D sensor is one of the inexpensive ways to capture an image and its corresponding depth map. The quality of the depth map and the DIBR algorithm are crucial to this process. Our approach is twofold. First, the depth maps captured directly by RGB-D sensors are generally of poor quality because there are many regions missing depth information, especially near the edges of objects. This paper proposes a new RGB-D sensor based depth map inpainting method that divides the regions with missing depths into interior holes and border holes. Different schemes are used to inpaint the different types of holes. Second, an improved hole filling approach for DIBR is proposed to synthesize the 3D images by using the corresponding color images and the inpainted depth maps. Extensive experiments were conducted on different evaluation datasets. The results show the effectiveness of our method.

     

A Theory of Minimal 3D Point to 3D Plane Registration and Its Generalization

Registration of 3D data is a key problem in many applications in computer vision, computer graphics and robotics. This paper provides a family of minimal solutions for the 3D-to-3D registration problem in which the 3D data are represented as points and planes. Such scenarios occur frequently when a 3D sensor provides 3D points and our goal is to register them to a 3D object represented by a set of planes. In order to compute the 6 degrees-of-freedom transformation between the sensor and the object, we need at least six points on three or more planes. We systematically investigate and develop pose estimation algorithms for several configurations, including all minimal configurations, that arise from the distribution of points on planes. We also identify the degenerate configurations in such registrations. The underlying algebraic equations used in many registration problems are the same and we show that many 2D-to-3D and 3D-to-3D pose estimation/registration algorithms involving points, lines, and planes can be mapped to the proposed framework. We validate our theory in simulations as well as in three real-world applications: registration of a robotic arm with an object using a contact sensor, registration of planar city models with 3D point clouds obtained using multi-view reconstruction, and registration between depth maps generated by a Kinect sensor.     

基于垂直采样的水下三维传感网覆盖算法

针对水下环境的三维传感器网络节点随机部署时存在覆盖率低的问题,设计一种基于垂直采样的水下三维传感网络覆盖算法,用于提高水下三维传感器网络覆盖率和连通性.垂直采样算法首先对三维监测区域进行垂直平面采样,然后再对该平面进行直线采样,把三维空间的覆盖问题转化为多平面内的直线覆盖优化问题,达到对整个三维网络覆盖优化的目的.仿真结果表明,在100 m×100 m×100 m的三维监测水域,垂直采样算法比三维随机部署策略可提高约4%~28%的覆盖率,在节点数为40时对覆盖率的提升程度最大.     

Optimal sensor placement and motion coordination for target tracking

This work studies optimal sensor placement and motion coordination strategies for mobile sensor networks. For a target-tracking application with range sensors, we investigate the determinant of the Fisher Information Matrix and compute it in the 2D and 3D cases, characterizing the global minima in the 2D case. We propose motion coordination algorithms that steer the mobile sensor network to an optimal deployment and that are amenable to a decentralized implementation. Finally, our numerical simulations illustrate how the proposed algorithms lead to improved performance of an extended Kalman filter in a target-tracking scenario.     

Alignment of continuous video onto 3D point clouds

We propose a general framework for aligning continuous (oblique) video onto 3D sensor data. We align a point cloud computed from the video onto the point cloud directly obtained from a 3D sensor. This is in contrast to existing techniques where the 2D images are aligned to a 3D model derived from the 3D sensor data. Using point clouds enables the alignment for scenes full of objects that are difficult to model; for example, trees. To compute 3D point clouds from video, motion stereo is used along with a state-of-the-art algorithm for camera pose estimation. Our experiments with real data demonstrate the advantages of the proposed registration algorithm for texturing models in large-scale semi-urban environments. The capability to align video before a 3D model is built from the 3D sensor data offers new practical opportunities for 3D modeling. We introduce a novel modeling-through-registration approach that fuses 3D information from both the 3D sensor and the video. Initial experiments with real data illustrate the potential of the proposed approach.     

结合个性化建模和深度数据的三维人体姿态估计

利用深度传感器估计三维人体姿态是计算机视觉领域的一个重要问题,在人机交互、虚拟现实和动画设计等领域有重要的应用价值.针对该问题的主流方法是自底向上的方法,这类方法一般采用分类、回归或检索技术,可以直接从深度数据中估计三维肢体姿态,在人机交互中得到了很广泛的应用.但是这类方法依赖于大规模的姿态数据库,而且结果不够精确.本文提出一种结合个性化人体建模和深度数据的三维姿态估计方法,首先对运动对象建立三维虚拟人模型,然后利用该个性化的虚拟人模型与深度数据之间的点匹配关系构造姿态优化的目标函数,通过迭代优化目标函数,估计出与深度数据相吻合的三维姿态.与传统方法相比,本文方法不需要任何姿态数据库.实验表明,本文方法得到的结果更加精确.     

三维水下监视传感器网络的拓扑生成算法

当前大多数传感器网络研究假设传感器节点在二维平面部署,然而许多水下传感器网络应用要求节点在三维空间分布。针对三维水下监视应用,提出一种新颖的分布式传感器网络拓扑生成算法（ETG）。基于格理论,ETG算法将节点的移动控制与活动设备的调度相结合。初始时刻监视设备密集部署在二维海平面上,ETG算法根据局部信息选择活动设备,并通过控制其传感器节点在垂直方向的移动,形成一个三维水下网络。仿真实验表明,ETG算法能够以较小的平均节点移动距离覆盖较大的空间,从而有效减少网络建立阶段的能量开销。     

应用于三维集成电路解析式布局的层分配算法

层分配是解析式三维集成电路布局算法中的关键一步。解析式布局需要通过层分配将连续的三维空间中的单元划分到二维的芯片层上,这个过程会破坏之前三维空间中得到的连续解。为了实现从优化的三维布局到合法的多层二维结构的平滑过渡,提出一种使用最小代价流的层分配方法,尽可能地继承三维优化结果,保护解空间。将此层分配算法嵌入到多层次的解析式三维集成电路布局算法中,以总线长和穿透硅通孔数目的加权总和为目标,面积密度为约束条件,对比当前其他三维布局算法,该算法得到较好的线长结果、穿透硅通孔数量和运行时间。     

Exploiting AML algorithm for multiple acoustic source 2D and 3D DOA estimations

The approximate maximum likelihood (AML) algorithm shows promises for joint estimations of acoustic source spectrum and direction-of-arrival (DOA). For the multisource case, the AML algorithm remains feasible as one considers an alternating projection procedure based on sequential iterative search on single source parameters. In order to perform multisource beamforming operations, earlier, we used a two-dimensional (2D) sensor array with 2D AML to obtain the DOA estimations for sources in the far field of t...     

基于数据结构化的三维动画压缩方法研究

在三维动画应用日益广泛的背景下,研究三维动画数据压缩方法对其数据的存储、传播和渲染 技术至关重要。基于图像数据的结构化特征,计算机视觉领域提出了一系列高效图像压缩技术。鉴于三维动画 数据与图像数据结构的差异,探讨三维动画数据结构化方法,进而探索改进图像算法以实现一种新的三维动画 数据压缩方法。具体而言,首先研究对三维模型顶点序列进行优化调整;进而基于图像压缩算法的模块研究动 画数据的子块尺寸优化以及图像压缩算法量化矩阵优化方法;最后,通过采用不同类型动画数据进行测试,实 验结果表明优化图像压缩算法在压缩比和时效均得到有效提升和保障。     

Branch pipe routing based on 3D connection graph and concurrent ant colony optimization algorithm

Pipe routing, in particular branch pipes with multiple terminals, has an important influence on product performance and reliability. This paper develops a new rectilinear branch pipe routing approach for automatic generation of the optimal rectilinear branch pipe routes in constrained spaces. Firstly, this paper presents a new 3D connection graph, which is constructed by extending a new 2D connection graph. The new 2D connection graph is constructed according to five criteria in discrete Manhattan spaces. The 3D connection graph can model the 3D constrained layout space efficiently. The length of pipelines and the number of bends are modeled as the optimal design goal considering the number of branch points and three types of engineering constraints. Three types of engineering constraints are modeled by this 3D graph and potential value. Secondly, a new concurrent Max–Min Ant System optimization algorithm, which adopts concurrent search strategy and dynamic update mechanism, is used to solve Rectilinear Branch Pipe Routing optimization problem. This algorithm can improve the search efficiency in 3D constrained layout space. Numerical comparisons with other current approaches in literatures demonstrate the efficiency and effectiveness of the proposed approach. Finally, a case study of pipe routing for aero-engines is conducted to validate this approach.     

二维解析张量投票算法研究

针对传统张量投票(Tensor voting)算法计算过程复杂、算法效率低的问题, 本文提出了一种二维解析张量投票算法.首先, 深入分析张量投票理论的基本思想, 分析传统张量投票算法的不足及其根源; 其次, 设计了一种二维解析棒张量投票新机制, 实现了二维解析棒张量投票的直接求取; 在此基础上, 利用二维解析棒张量投票不依赖参考坐标系的特性, 设计并求解了二维解析球张量投票表达式, 解决了长期困扰张量投票理论中球张量投票无法解析求解, 仅能通过迭代数值计算, 计算过程复杂、算法效率低、算法精度与算法效率存在矛盾的难题.最后, 通过仿真分析和对比实验验证了本文算法在精度和计算效率方面的性能均优于传统张量投票算法.     

A novel 3D sensory system for robot-assisted mapping of cluttered urban search and rescue environments

In this paper, the first application of utilizing a unique 3D sensor for sequential 3D map building in unknown cluttered urban search and rescue (USAR) environments is proposed. The sensor utilizes a digital fringe projection and phase shifting technique to provide real-time 2D and 3D sensory information of the environment. The proposed sensor is unique over current technologies in that high-resolution 3D information of rubble filled environments can be acquired from the single sensor at a speed of 30 frames per second (fps). Furthermore, we propose the development of a novel robust and reliable landmark identification technique that utilizes both 2D and 3D depth images taken by the sensor for 3D mapping. Preliminary experiments show the potential of the real-time 3D sensory system and landmark identification scheme for robotic 3D mapping in unknown cluttered USAR-like environments.     

Interactive 3D visualization for wireless sensor networks

Wireless sensor networks open up a new realm of ubiquitous computing applications based on distributed large-scale data collection by embedded sensor nodes that are wirelessly connected and seamlessly integrated within the environment. 3D visualization of sensory data is a challenging issue, however, due to the large number of sensors used in typical deployments, continuous data streams, and constantly varying network topology. This paper describes a practical approach for interactive 3D visualization of wireless sensor network data. A regular 3D grid is reconstructed using scattered sensor data points and used to generate view-dependent 2D slices that are consequently rendered with commodity graphics hardware leading to smooth visualization over space and time. Furthermore, the use of efficient space partitioning data structures and the independent processing of sensor data points facilitates interactive rendering for large number of sensors while accommodating constantly changing network topology. The practical value of the proposed method is demonstrated and results obtained for visualizing time-varying temperature distributions in an urban area are presented.     

Breaking Symmetries and Constraints: Transitions from 2D to 3D in Passive Walkers

The inherent dynamics of bipedal, passive mechanisms are studiedto investigate the relation between motions constrained to two-dimensional (2D)planes and those free to move in a three-dimensional (3D) environment. Inparticular, we develop numerical and analytical techniques usingdynamical-systems methodology to address the persistence and stabilitychanges of periodic, gait-like motions due to the relaxation ofconfiguration constraints and the breaking of problem symmetries. Theresults indicate the limitations of a 2D analysis to predictthe dynamics in the 3D environment. For example, it is shownhow the loss of constraints may introduce characteristically non-2Dinstability mechanisms, and how small symmetry-breaking terms may result inthe termination of solution branches.     

基于体心立方格的三维传感器网络部署与组织

三维传感器网络有着重要的应用前景,而目前传感器网络的研究主要集中在二维。针对传感器节点在空间中的部署和组织,本文提出一种体心立方格结构传感器网络的确定部署方法,以及一种基于空间虚拟Voronoi单元的随机部署三维传感器网络的节点组织策略。     

Automatic sensor placement for model-based robot vision.

This paper presents a method for automatic sensor placement for model-based robot vision. In such a vision system, the sensor often needs to be moved from one pose to another around the object to observe all features of interest. This allows multiple three-dimensional (3-D) images to be taken from different vantage viewpoints. The task involves determination of the optimal sensor placements and a shortest path through these viewpoints. During the sensor planning, object features are resampled as individual points attached with surface normals. The optimal sensor placement graph is achieved by a genetic algorithm in which a min-max criterion is used for the evaluation. A shortest path is determined by Christofides algorithm. A Viewpoint Planner is developed to generate the sensor placement plan. It includes many functions, such as 3-D animation of the object geometry, sensor specification, initialization of the viewpoint number and their distribution, viewpoint evolution, shortest path computation, scene simulation of a specific viewpoint, parameter amendment. Experiments are also carried out on a real robot vision system to demonstrate the effectiveness of the proposed method.