Team O2AS' approach for the task-board task of the World Robot Challenge 2018

ABSTRACT

In this paper, we describe the approach of Team O2AS to complete the task-board task of the World Robot Challenge 2018, held in Tokyo. We use a custom gripper and graspable tools with in-built compliance to work with various kinds of parts, increase robustness against uncertainties, and to avoid complicated control strategies. The robots are able to finish all the sub-tasks without the need to exchange grippers. The main idea is to use mechanical compliance and self-centering mechanisms to deal with uncertainty. This is achieved by aligning the objects using either the gripper and tools, or by the design of the robot motions.     

Improvement of alignment quality for FLC with mixing liquid crystal polymer

Ferroelectric liquid crystal (FLC) with I‐N*‐C* phase sequence is most attractive due to its continuous grey level and fast response; however, the alignment problem of two‐domains defect restricted its application. In this work, one kind of one terminal polymerizable nematic liquid crystal (NLC) mesogen was mixed to FLC to improve its alignment quality. Experimental results showed that mono‐domain uniform alignment of FLC can be obtained with mixing NLC polymer. With optimized concentration, the FLC devices could offer half‐V‐shaped electric‐optical characteristic of driving contrast of 182:1 and fast response of 300 µs even after polymerization. This work can provide one simple and effective method for fabricating stable I‐N*‐C* FLC devices.     

Electron injection barrier and energy-level alignment at the Au/PDI8-CN2 interface via current–voltage measurements and ballistic emission microscopy

We probe electron transport across the Au/organic interface based on oriented thin films of the high-performance n-type perylene diimide semiconductor PDI8-CN₂. To this purpose, we prepared organic-on-inorganic Schottky diodes, with Au directly evaporated onto PDI8-CN₂ grown on n-Si. Temperature-dependent current–voltage characteristics and complementary ballistic electron emission microscopy studies reveal that rectification at the Au/PDI8-CN₂ interface is controlled by a spatially inhomogeneous injection barrier, that varies on a length scale of tens of nanometers according to a Gaussian distribution with mean value ∼0.94 eV and standard deviation ∼100 meV. The former gradually shifts to ∼1.04 eV on increasing PDI8-CN₂ thickness from 5 nm to 50 nm. Experimental evidences and general arguments further allow to establish the energetics at the Au/PDI8-CN₂ interface. Our work indicates injection-limited current flow in PDI8-CN₂-based devices with evaporated Au electrodes. Furthermore, it suggests chemical reactivity of PDI8-CN₂ with both Au and Si, driven by the lateral isocyano groups.     

基于拼接缝自适应消除和全景图矫直的快速图像拼接算法

针对图像拼接存在色差过渡不均匀、图像倾斜扭曲及拼接效率低的现象，提出一种基于拼接缝自适应消除和全景图矫直的快速图像拼接算法。首先，用尺度不变特征变换（SIFT）提取图像指定区域特征点并用双向K近邻（KNN）算法进行图像配准，有效提高算法效率；其次，利用动态规划思想提出自适应公式找到最优拼接缝并用图像融合算法对其自适应消除，解决拼接缝色差过渡不均匀问题；最后，针对累积拼接误差形成全景图倾斜的现象，利用边缘检测算法提出自适应拟合四边形矫直模型，把原始全景图矫直为一个全新的全景图。所提算法与分块图像拼接和二叉树图像拼接算法相比，图像质量提升了5.84%~7.83%，拼接时间仅为原来的50%~70%。实验结果表明，该算法不仅通过自适应更新机制减少不同图像背景下拼接缝色差过渡不均匀的现象，从而提高了图像质量；而且提高了拼接效率，降低了全景图倾斜扭曲程度。     

Effect of TiB2 addition on grain orientation of porous Si3N4-TiB2 composites by magnetic field alignment technology

Textured porous Si₃N₄-TiB₂ composites were prepared by gel-casting–assisted magnetic field alignment technology and subsequent pressureless sintering in the N₂ atmosphere. The effects of TiB₂ content on grain orientation and properties of composites were studied. Results showed that using the magnetic field of 6T, Si₃N₄ grains exhibited a high a- or b-axis orientation and TiB₂ grains exhibited a high c-axis orientation. In textured green bodies, the increase in TiB₂ content from 0 to 20 wt%, the degree of texture of Si₃N₄ grains showed a slight decrease from 0.78 to 0.71. However, the degree of texture of TiB₂ grains was maintained at about 0.98 regardless of TiB₂ content. After sintering, except for the Si₃N₄ and TiB₂ phases, new TiN and BN phases also appeared in the samples. Additionally, the sintering process promotes grain orientation of Si₃N₄ and TiB₂. Herein, the degree of texture of TiB₂ reached to about 1 regardless of TiB₂ content, meaning that the complete grain orientation formed for TiB₂. Owing to the reconstruction reaction between TiB₂ and N₂, new TiN and BN phases did not form the orientation. The increase in TiB₂ contents gradually increased the apparent porosity of the textured samples from 27.9% to 39.4%, thereby leading to the decrease in bending strength from 126.8 ± 18.8 MPa to 60.3 ± 11.2 MPa and from 105.3 ± 19.8 MPa to 53.6 ± 13.0 MPa in two directions, respectively.     

智能式压力试验机课题研究

混凝土弹性模量是铁路梁场生产过程的重要控制指标,试验结果直接影响梁场生产进度与桥梁质量,而影响该项试验结果准确性的主要因素为试验设备智能化水平及操作过程信息化程度。通过本课题的研究,可提高弹模试验数据的准确性、及时性、完整性,减少弹模试验中试验人员数量,有效缩短弹模试验时间,实现弹性模量试验数据上传至工程管理平台,通过大数据对试验结果进行分析总结,为铁路领域梁体质量控制提供技术保障。     

Controlling the interface energetics of PCPDTBT by p-doping

The doping of organic semiconductors is a promising way for both improving the charge carrier transport and tuning the energy level alignment at interfaces. We study the influence of p-doping of the low band gap polymer PCPDTBT with F4-TCNQ on the energy level alignment in a prototype organic solar cell structure with ITO as an electrode material and the fullerene C₆₀ as electron acceptor material using Ultraviolet and X-ray photoelectron spectroscopy. As a consequence of the doping, a Quasi-Ohmic contact at the interface to ITO is formed, whereas the energy level alignment to C₆₀ is almost not affected. In contrast to a related system, we observe a depletion of the dopant at the polymer surface. The change of the energy level alignment only at the electrode interface might be advantageous for the application in organic solar cell devices.     

Offshore wind turbine blades measurement using Coherent Laser Radar

To maximize aerodynamic efficiency, large-scale offshore wind turbine blades require inspection during the production stage to ensure strict tolerance requirements are met. During production, the blade is fixed at the root, restricting movement in the Z direction. X, Y, Rx, Ry and Rz remain unconstrained causing blade flex due to gravity. This deforms the blade away from the theoretical CAD blade location, causing measurement results that do not accurately represent the blade profile. Measurement error can be minimized using rigorous B-spline data alignment. Such alignment compensates for blade flex by varying the constrained Degrees of Freedom (DoF), and provides manufacturers with confidence in the design process. This paper used Coherent Laser Radar and Spatial Analyzer to establish the optimal constrained DoF variation, giving the most accurate data alignment solution. Of the constraints investigated, the optimal data transformation solution was found with a double B-spline alignment method, whilst constraining movement in Y, Z and Ry.     

Hybrid multiobjective artificial bee colony for multiple sequence alignment

In the bioinformatics community, it is really important to find an accurate and simultaneous alignment among diverse biological sequences which are assumed to have an evolutionary relationship. From the alignment, the sequences homology is inferred and the shared evolutionary origins among the sequences are extracted by using phylogenetic analysis. This problem is known as the multiple sequence alignment (MSA) problem. In the literature, several approaches have been proposed to solve the MSA problem, such as progressive alignments methods, consistency-based algorithms, or genetic algorithms (GAs). In this work, we propose a Hybrid Multiobjective Evolutionary Algorithm based on the behaviour of honey bees for solving the MSA problem, the hybrid multiobjective artificial bee colony (HMOABC) algorithm. HMOABC considers two objective functions with the aim of preserving the quality and consistency of the alignment: the weighted sum-of-pairs function with affine gap penalties (WSP) and the number of totally conserved (TC) columns score. In order to assess the accuracy of HMOABC, we have used the BAliBASE benchmark (version 3.0), which according to the developers presents more challenging test cases representing the real problems encountered when aligning large sets of complex sequences. Our multiobjective approach has been compared with 13 well-known methods in bioinformatics field and with other 6 evolutionary algorithms published in the literature.     

优化特征提取的互动式人脸活体检测研究

针对人脸识别系统中出现的通过照片或视频“欺诈”解锁问题，提出一种活体检测方法，通过随机指令判断被检测对象是否为真人。利用HOG特征和随机森林算法对摄像头采集的图像进行人脸检测，预测脸部68个特征点位置，把68个特征点位置和脸部位置的相对位置归一化后作为姿态的特征，提取的姿态特征与SVM分类器相结合，训练出分类效果较好的头部姿态估计分类器。通过多次实验，对特征提取方法进行优化，进一步提高检测准确率。最后，使用随机互动式命令序列对被检测人发出指令，实现活体检测。该方法对头部姿态估计具有较高的鲁棒性，并且可以有效地防范照片和视频认证攻击。