Shenyang Institute of Automation,Chinese Academy Of Sciences
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An obstacle avoidance algorithm for space hyper-redundant manipulators using combination of RRT and shape control method
No full textThis paper proposes a kinematic obstacle avoidance algorithm for Space hyper-redundant manipulators, and its basic idea is to use a static and a dynamic curve to constrain the macroshape of the manipulators simultaneously. The static curve is constructed based on a traditional rapidly exploring random tree algorithm, and a backbone curve is utilized as the dynamic curve. For these two curves, two novel shape control methods are proposed to accomplish the shape constraining process. Finally, we verify the reliability and effectiveness of our algorithm through simulations
Depth Selection for Deep ReLU Nets in Feature Extraction and Generalization
No full textDeep learning is recognized to be capable of discovering deep features for representation learning and pattern recognition without requiring elegant feature engineering techniques by taking advantages of human ingenuity and prior knowledge. Thus it has triggered enormous research activities in machine learning and pattern recognition. One of the most important challenges of deep learning is to figure out relations between a feature and the depth of deep neural networks (deep nets for short) to reflect the necessity of depth. Our purpose is to quantify this feature-depth correspondence in feature extraction and generalization. We present the adaptivity of features to depths and vice-verse via showing a depth-parameter trade-off in extracting both single feature and composite features. Based on these results, we prove that implementing the classical empirical risk minimization on deep nets can achieve the optimal generalization performance for numerous learning tasks. Our theoretical results are verified by a series of numerical experiments including toy simulations and a real application of earthquake seismic intensity prediction
Research on the ultimate strength of spherical shell cover plus cylindrical shell pressure hulls
No full text耐压舱设计是水下机器人的核心技术之一，其极限承载力研究是核心中的核心。针对球壳封盖加柱形壳体耐压舱，现行标准对于初始导入缺陷数值的确定往往过于保守，对于耐压舱体数量较多的无人潜水器来说，过大的设计质量是总体设计所无法接受的。首先采用装配体整体建模策略，建立复合屈曲的受力模型，将三大非线性影响因素同时引入到极限承载力研究中，提升了计算精度。然后分别针对确定性缺陷和非确定性缺陷结构开展极限承载力研究。最后，提出以0.23%的初始缺陷导入尺度作为球壳封盖加圆柱壳体的耐压壳体缺陷导入参数，给出了导入尺度的计算方法，并借助水压试验对上述参数的准确性进行验证。</p
Research on Dynamic Uniform Loading Method of Grain Box of Transport Vehicle Based on Three-dimensional Point Cloud
No full text为了解决联合收获机-运输车协同作业时，运输车粮箱装载不均匀，导致粮箱装载利用率低的问题，提出了一种基于三维点云的动态均匀装载方法。该方法利用相机获取运输车粮箱内装载物的三维点云作为状态反馈信息，建立装载均匀性评估方式，以最均匀装载状态为目标，通过实时调整卸料装载点位置，使粮箱保持在均匀的装载状态。针对装载物相互遮挡对相机形成视觉盲区的问题，通过建立装载物的堆体模型和相机的遮挡模型，以最小期望误差对盲区内装载物高度进行估计，并据此进行点云填充，从而得到能完整反映粮箱装载状态的三维点云。在搭建平台进行的实验中，对粮箱装载过程中可能出现的轻载、中载和重载3种装载状态进行测量，并对盲区点云位置进行估计，其盲区估计的平均误差低于5cm。仿真结果表明，动态均匀装载方法能在有限装载周期内，将粮箱从任意的初始装载状态装载为均匀状态。单次装载量的平均高度增量为2cm，粮箱的初始装载状态为空载时，装载物的最大高度方差为1cm2。单因素仿真结果表明，稳定状态下的装载物高度方差与单次装载量正相关。</p
Research on accurate modeling of hydrodynamic interaction forces on AUVs operating in tandem
No full textThe hydrodynamic interaction force between autonomous underwater vehicles (AUVs) operating in tandem can adversely affect the hydrodynamic prediction of individual AUVs and the formation control of the tandem fleet. Accurate modeling of hydrodynamic interaction forces is crucial to the model-based controller design of AUVs. In this paper, we innovatively propose a modeling method that can describe the hydrodynamic interaction relationship accurately and continuously (when the spacing between adjacent AUVs changes). First, an accurate hydrodynamic model for individual AUVs in tandem fleets is established by modifying the typical model through the consideration of memory effects. Second, a model of hydrodynamic interaction forces is derived by subtracting hydrodynamic forces acting on a single AUV operating independently from those acting on an AUV operating in tandem. To enable this model to continuously describe the hydrodynamic interaction relationship when the spacing changes, this model is further derived by taking the spacing as an independent variable based on the parameter conversion method. Finally, planar motion mechanism (PMM) tests are carried out using the computational fluid dynamics (CFD) method to verify the accuracy and continuity of the proposed modeling method. The results show that compared with the typical model, the average error of hydrodynamic forces predicted by the proposed model is reduced by 5.36%, which verifies the feasibility and effectiveness of the proposed modeling method.</p
Research on cloud-side collaborative task migration strategy based on simulated annealing-Bee Colony Algorithm in Power IoT
No full textIn the power IoT, in order to make up for the shortcomings of insufficient computing capabilities of edge-side devices, cloud-side collaboration technology has attracted more and more attention. The cloud-side collaboration technology relies on the selection of task migration strategies. However, when the existing migration strategies face the complex edge-side terminal devices in the power IoT, the energy consumption and delay performance are not good enough, which greatly affects the user's power experience. Therefore, it is very valuable to study a cloud-side collaborative task migration strategy under the power IoT environment. This paper proposes a task migration strategy based on simulated annealing-Bee Colony Algorithm in the environment of power IoT, which can solve the problem of task migration. Experimental results show that compared with the existing popular methods, this method has advantages in terms of energy consumption and time delay. This research can meet the real-time requirements of the power IoT, while reducing energy consumption and improving the user's power experience, thereby promoting the further development of the power IoT
An obstacle avoidance algorithm for space hyper-redundant manipulators using combination of RRT and shape control method
No full textThis paper proposes a kinematic obstacle avoidance algorithm for Space hyper-redundant manipulators, and its basic idea is to use a static and a dynamic curve to constrain the macroshape of the manipulators simultaneously. The static curve is constructed based on a traditional rapidly exploring random tree algorithm, and a backbone curve is utilized as the dynamic curve. For these two curves, two novel shape control methods are proposed to accomplish the shape constraining process. Finally, we verify the reliability and effectiveness of our algorithm through simulations. © The Author(s), 2021. Published by Cambridge University Press.</p
Straight Skeleton Filling Algorithm of Slice Contour for Thin-walled Parts by Additive Manufacturing
No full text针对增材制造薄壁件采用传统轮廓填充算法易导致内部缺陷的问题，研究了增材制造薄壁件分层轮廓直骨架填充算法。该算法首先对截面分层轮廓进行简化、平滑等预处理，然后对预处理之后的多边形轮廓进行直骨架计算，并提取直骨架半边数据结构中由所有内等分线构成的直骨架主线串。在对直骨架主线串进行膨胀操作和多边形合并操作之后，最后应用轮廓平行偏置算法获得薄壁件分层轮廓直骨架偏置填充轨迹。提出的算法较好解决了薄壁零件增材制造由于轨迹填充不合理导致的内部缺陷。</p
Fully Reduced HMGB1-Containing Peptide-Based Polyurethane Scaffold with Minimal Functional Unit of Skin (MFUS) Enhances Large and Deep Wounded Skin Healing
No full textA novel peptide-based polymer is developed by lysine-diisocyanate (LDI), glycerol (Gly), and fully reduced HMGB1 (frHMGB1). This frHMGB1-LDI-Gly polymer either forms sponge-like foam (scaffold) or a hydrogel or a film under different reaction conditions. It degrades into nontoxic lysine, glycerol, and frHMGB1. The hydrogel glues tissues together and the glued tissues have strong mechanical properties. The film and scaffold provide the suitable environment for enhancing cell proliferation by releasing frHMGB1. The scaffold carries 1 mm diameter of full-thickness rat skin-island as a minimal functional unit of skin (MFUS) to treat large full thickness skin wounds, and the hydrogel glues the MFUS and scaffold with skin edges together (MFUS+Scaffold group). The scaffold treated wounds (Scaffold group) heal much faster than the wounds either treated with MFUS (MFUS group) or without treatment (Wound group). The MFUS+Scaffold treated wound regenerates more functional full-thickness skin with more hair follicles and sweat glands, higher CD146 and alpha-smooth muscle actin levels, more blood vessels and collagen productions, and less scar tissues when compared to the other three groups. The results demonstrate that the combination of frHMGB1-LDI-Gly polymer with MFUS provides a new tissue engineering approach for large full-thickness skin wound healing.</p
Visual Measurement Method of Gap Width of Split Type Ammunition Based on Improved Ostu-Sobel
No full text在分体式炮弹产品的质量检测中，螺纹连接处间隙的高精度稳定测量是保证炮弹质量的重要指标之一。为了精确测量螺纹连接处间隙，利用机器视觉的方法，提出了一种基于改进Otsu-Sobel的分体式炮弹缝宽视觉测量方法。该方法根据图像特征生成自适应感兴趣区域，再通过单调化处理与Sobel算子确定缝隙边缘的粗定位区间，在局部利用图像梯度的离散度精确定位缝隙边缘。为解决机械安装、缝宽倒角等因素对精度的影响，利用了最小二乘拟合方法对测量结果进行修正。实验结果表明，该方法可精确检测0.1～0.7mm的缝宽，且其测量误差小于0.02mm。该方法解决了分体式炮弹螺纹连接处间隙精确测量的技术难题，可满足产品质量检测的需要。</p