Noise analysis and synthesis for 3D laser depth scanners

This paper analyses the noise present in range data measured by a Konica Minolta Vivid 910 scanner, in order to better characterise real scanner noise. Methods for denoising 3D mesh data have often assumed the noise to be Gaussian, and independently distributed at each mesh point. We show via measurements of an accurately machined almost planar test surface that real scanner data does not have such properties: the errors are not quite Gaussian, and more importantly, exhibit significant short range correlation. We use this to give a simple model for generating noise with similar characteristics. We also consider how noise varies with such factors as laser intensity, orientation of the surface, and distance from the scanner. Finally, we evaluate the performance of three typical mesh denoising algorithms using real and synthetic test data, and suggest that new denoising algorithms are required for effective removal of real noise.     

Efficient autonomous global localization for service robots using dual laser scanners and rotational motion

This study presents an alternative global localization scheme that uses dual laser scanners and the pure rotational motion of a mobile robot. The proposed method extracts the initial state of the robot’s surroundings to select robot pose candidates, and determines the sample distribution based on the given area map. Localization success is determined by calculating the similarity of the robot’s sensor state compared to that which would be expected at the estimated pose on the given map. In both simulations and experiments, the proposed method shows sufficient efficiency and speed to be considered robust to real-world conditions and applications.

     

激光干涉光刻工艺开发与应用研究

成功开发出以劳厄干涉为基础的激光干涉光刻系统与工艺,该工艺可在大面积范围内加工二维周期性图形,非常适合于生产光电子器件和微电子器件的周期性结构。通过实验研究了使用该工艺加工表面纳米结构的流程,对比了几种光刻胶在该工艺中的性能特点。该工艺不需要掩模、昂贵的短波长光源和成像透镜。初步实验结果表明:该工艺可以生产大面积亚微米周期的光栅、点阵以及锥形结构,为激光干涉光刻加工纳米结构的后续工作奠定了基础。     

Development of miniaturized piezoelectric actuators for opticalapplications realized using LIGA technology

To combine the advantages of the LIGA technology and piezoelectric materials, first prototypes of movable elastic LIGA structures have been realized on piezoelectric substrates. The structures consist of a flexible beam fixed to the piezoelectric substrate at its two ends in order to amplify the d₃₁-contraction of the piezoelectric substrate. By using this flexible LIGA beam as a magnification mechanism, the small displacements of the piezoelectric substrate are amplified by more than a factor of 20, offering various possibilities of applications, especially in micro-optics. In this paper, first the fabrication process and the performance of these new prototypes of LIGA piezoelectric actuators are described in detail, demonstrating the feasibility of the new concept combining the LIGA technique and piezoelectric substrates. Subsequently, LIGA-piezoelectric actuators developed for micro-optical applications are presented. These new optical actuators are also based on an elastic beam but slightly modified in order to modulate light propagating in optical fibers. They find promising applications as micro-optical attenuators or choppers whose performance is demonstrated     

Laser micro-welding of aluminum and copper with and without tin foil alloy

In this paper continuous laser welding of two dissimilar materials, aluminum and copper, was investigated. The aluminum and the copper utilized were Al3003-H14 and Cu110-H00, respectively. Two different sets of samples were laser welded; one in which a filler material, tin foil alloy (S-bond 220), was sandwiched between the aluminum and the copper and another set in which the aluminum and copper were directly welded without any filler. The foil alloy was utilized to enhance the compatibility of the two metals; aluminum and copper, reducing the brittleness of the intermetallic compound that may form and, subsequently, enhance the mechanical properties. The welding was carried out using an IPG 500 SM fiber laser. The length of the laser joint produced was 20 mm and the width was about 200 μm. The strength of the joint was evaluated by conducting the lap shear stress test. Samples in which filler foil was used exhibited a better performance in the lap shear stress test (an average of 780 N) than the samples without tin foil (an average of 650 N). The improvement in the lap shear test could be attributed to the positive effects of the filler on enhancing the compatibility of the intermetallic compound formed via diffusion. The fracture surface of both types of joints (with and without filler) was characterized using scanning electron microscope equipped with energy-dispersive X-ray (EDAX). To understand the failure initiation and propagation of the samples under tension, a finite element (FE) model was developed for the samples created with no filler material. The failure mechanism predicted from the FE model matches reasonably well with the experimental observations from EDAX analysis.     

Methods for characterizing colour scanners and digital cameras

After a brief introduction to the principles of colour management of both device dependent and independent systems the principles of scanner and camera characterisation are discussed in relation to the ANSI/ISO tools developed for this purpose. Procedures are outlined for the evaluation of such devices in terms of their ability to provide satisfactory colour reproduction, and then the techniques which may be used to achieve the necessary characterisation are discussed. These include least-squares fitting, non-linear transformations, dye combination modelling and look-up-tables with interpolation. Many of the important issues associated with characterisation, such as gamut mapping and appearance modelling, are not discussed in this paper but in the paper on printer characterisation also in this issue.     

微球探针激光快速加工成形系统设计

为了方便快捷地制备微球探针,设计了一种微球探针激光快速加工成形系统.该系统主要由激光光源、激光控制器、光束调整组件、机械定位组件四个部分构成.通过该系统对微球探针进行加工实验,得到了尖端无明显缺陷且具有较好球形质量的微球探针,实验表明:该激光快速加工成形系统能够满足微球探针快速成形的制备要求.     

Ultra thin chips for miniaturized products

The demand to miniaturize products especially for mobile applications and autonomous systems is continuing to drive the evolution of electronic products and manufacturing methods. One key to miniaturization developed in the past was the use of unpackaged, bare dice. Saving the volume and weight of the package, significant reduction in footprint was achieved. A next step conceived to further the miniaturization is the integration of functions on miniaturized subsystems, i.e. System-in-Package (SiP), in contrast to a full silicon integration (System-on-Chip, SoC). The use of recent manufacturing methods allows to merge the SiP approach with a volumetric integration. Up to now, most of the systems utilize single- or double-sided populated system carriers. Embedding of passive components was a first step forward. A new challenge is to incorporate not only passive components, but active circuitry (IC's) and the necessary thermal management as well. Ultra thin chips (i.e. silicon dies thinned down to 50 m total thickness) lend themselves to reach these goals. Chips with that thickness can be embedded in the dielectric layers of modern laminate PCB's. Micro via technology allows to connect the embedded chip to the outer faces of the system circuitry. As an ultimate goal for microsystem integration, the embedding of optical and fluidical system components can be envisioned. This paper presents the first approach to embed thin silicon dies in to polymeric system carriers. The aspects of embedding and making the electrical contact as well as the thermal management are highlighted. To reach the goal of a vertically stackable box-of-bricks type of ultra thin (UT) package, thin silicon chips are embedded and interconnected on a peripheral UT BGA.The authors would like to thank the team of the 3D-CSP and the ChiP task force at IZM Berlin/Munich and TU Berlin as well as the colleagues from the PCB industry having supported this feasibility study with activity and discussion. Part of the work shown here is done in of the BMBF Project Systemintegration in polymere Schaltungsträger, No.02PP2051, co-ordinated by the FZK-PFT. The support is gratefully acknowledged.This paper was presented at the Conference of Micro System Technologies 2001 in March 2001     

Reconstructing a textured CAD model of an urban environment using vehicle-borne laser range scanners and line cameras

Abstract. In this paper, a novel method is presented for generating a textured CAD model of an outdoor urban environment using a vehicle-borne sensor system. In data measurement, three single-row laser range scanners and six line cameras are mounted on a measurement vehicle, which has been equipped with a GPS/INS/Odometer-based navigation system. Laser range and line images are measured as the vehicle moves forward. They are synchronized with the navigation system so they can be geo-referenced to a world coordinate system. Generation of the CAD model is conducted in two steps. A geometric model is first generated using the geo-referenced laser range data, where urban features, such as buildings, ground surfaces, and trees are extracted in a hierarchical way. Different urban features are represented using different geometric primitives, such as a planar face, a triangulated irregular network (TIN), and a triangle. The texture of the urban features is generated by projecting and resampling line images onto the geometric model. An outdoor experiment is conducted, and a textured CAD model of a real urban environment is reconstructed in a full automatic mode.     

An online framework for catching top spreaders and scanners

Flow level information is important for many applications in network measurement and analysis. In this work, we tackle the “Top Spreaders” and “Top Scanners” problems, where hosts that are spreading the largest numbers of flows, especially small flows, must be efficiently and accurately identified. The identification of these top users can be very helpful in network management, traffic engineering, application behavior analysis, and anomaly detection.We propose novel streaming algorithms and a “Filter-Tracker-Digester” framework to catch the top spreaders and scanners online. Our framework combines sampling and streaming algorithms, as well as deterministic and randomized algorithms, in such a way that they can effectively help each other to improve accuracy while reducing memory usage and processing time. To our knowledge, we are the first to tackle the “Top Scanners” problem in a streaming way. We address several challenges, namely: traffic scale, skewness, speed, memory usage, and result accuracy. The performance bounds of our algorithms are derived analytically, and are also evaluated by both real and synthetic traces, where we show our algorithm can achieve accuracy and speed of at least an order of magnitude higher than existing approaches.     

MEMS AC voltage reference for miniaturized instrumentation and metrology

This work explores MEMS (Micro-Electro-Mechanical Systems) potentialities to fabricate AC voltage references through mechanical-electrical transduction that could be used for high precision electrical metrology and for applications in miniaturized instrumentation. AC voltage reference ranging from 5 V to 90 V have been designed and fabricated using the same Epitaxial Silicon On Insulator (SOI) surface micromachining process allowing an accurate control of both dimensions and material properties. The measured MEMS AC voltage reference values have been found in a good agreement with CoventorWare calculations. These tests structures have also been used to develop the read-out electronics to drive the MEMS.     

医用内窥镜微型摄像模组设计

设计了一种新型医用内窥镜微型摄像模组.该模组采用微型、高分辨率的CMOS图像传感器结合低压差分信号（LVDS）传输技术进行设计,使摄像模组直径缩减至5.0mm,并实现了图像数据的长距离高保真传输.搭建了实验平台对摄像模组的摄像功能进行了测试.结果表明：该模组图像传输距离超过2m,分辨率达到30万像素,对口腔溃疡模拟粘膜病变的识别率高达90％.其图像分辨率高,传输距离长,使其适用于内镜诊断;其直径小,能大大提高病人内镜检查的舒适性,为超细内镜诊断提供了一种极佳的解决方案.     

CAN总线应用层协议的研究与实现

在研究CAN协议的原理及应用技术的基础上,为了满足波控系统控制策略的需要,设计了CAN总线应用层协议。该协议对网络信息进行了分类,在CAN2.0B标准基础上重新定义了标识符域,并对数据编码、网络管理机制和物理接口等作了定义。介绍了所开发的基于CAN总线的控制网络。实际运行表明,该协议具有网络负载小、通讯实时性好和可靠性高的特点。     

弹性梁刚度矩阵算法及应用

通过实例介绍了一种实用简单的弹性梁结构刚度矩阵计算方法,可广泛应用于含有弹性梁结构的惯性器件如传感器的设计中。最后介绍了该算法的一种应用,并用ANSYS有限元软件分析验证了其正确性。     

Thermocapillary mechanism of deep penetration in laser beam welding

Inconsistencies between experimental data and concepts of the vaporization hypothesis, assuming melt displacement by the pressure of vapor recoil, are sufficient to doubt the applicability of this hypothesis for the simulation of deep penetration welding. In order to settle these inconsistencies, a hypothesis was proposed, including an associated model, which attributes the removal of the melt from the zone of the beam impact and the formation of a deep penetration channel to the action of tangential thermocapillary forces on a heterogeneously heated surface. The phenomenon of a deep penetration channel appears as a result at an excess of the threshold value of beam intensity, when the structural rearrangement of the thermocapillary divergent flow is observed, interrelated with a break-age of flow lines at the transition from the vortex mode to the shear mode. The thermocapillary model of deep penetration was verified by comparing the major parameters of the deep penetration process, obtained by calculations, with empirical data.     

磁致伸缩传感器技术应用的发展

随着传感器应用领域的不断扩大,磁致伸缩传感器技术也得到了迅猛的发展。回顾了磁致伸缩传感器在力学、磁学、材料检测、微位移及声学等领域的应用,指出了存在的不足,同时对今后的发展进行了展望。     

Use of wrist mounted range profile scanners for real-time tracking

The results of experiments in realtime tracking of a moving object using wrist mounted laser range finders are presented. The objective is to have the robot endeffector maintain a constant pose with respect to a flat object moving in three-dimensional space in the field of view of the range finders. Tracking is done with maximum linear and angular speeds of the target object being 25 cm/s and 0.5 rad/s, respectively. The software is designed to ensure that the robot has smooth motion, without any sharp discontinuities. A performance study of the tracking experiment is presented.NRC #33164     

A state observer for nonlinear systems and its application to balland beam system

In this paper, we present a state observer for single-input/single-output nonlinear systems which fail to have well defined relative degree. It is shown that there exists a local state observer for a nonlinear system if it has robust relative degree n. The proposed observer utilizes the coordinate change which transforms a system into an approximate normal form. The proposed method is applied to a ball and beam system, and simulation results show that substantial improvement in the performance was achieved compared with other local observers     

随钻测量用微小型惯性测量单元设计

为满足随钻测量仪器在小口径油井、高频振动、强冲击等环境中的应用需求,使用光纤陀螺与石英挠性加速度计作为传感器组件,设计加速度计信号采样电路,小型化导航计算模块采用SOPC＋SDRAM＋FLASH,完成传感器信号采集、误差补偿、导航解算以及与上位机通信等功能。惯性测量单元（ IMU）集成了电源模块、传感器组件和导航计算机,最终制作成38 mm的随钻测量仪器。实验结果表明：当井斜角不小于5°时,样机能够达到系统姿态解算精度要求（井斜角误差小于±0.2°,方位角误差小于±2°,工具面角误差小于±0.2°）。