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15 January 2014, Volume 19 Issue 1 Previous Issue    Next Issue

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Central Pattern Generator Based Gait Control for Planar Quadruped Robots LI Jia-wang (李家旺), WU Chao (吴 超), GE Tong* (葛 彤) 2014, 19 (1):  1-10.  doi: 10.1007/s12204-014-1470-1 Abstract ( 1107 )   In this paper, a gait control scheme is presented for planar quadruped robots based on a biologic concept, namely central pattern generator (CPG). A CPG is modeled as a group of the coupled nonlinear oscillators with an interaction weighting matrix which determines the gait patterns. The CPG model, mapping functions and a proportional-differential (PD) joint controller compose the basic gait generator. By using the duty factor of gait patterns as a tonic signal, the activity of the CPG model can be modulated, and as a result, a smooth transition between different gait patterns is achieved. Moreover, by tuning the parameters of the CPG model and mapping functions, the proposed basic gait generator can realize adaptive workspace trajectories for the robot to suit different terrains. Simulation results illustrate and validate the effectiveness of the proposed gait controllers. References | Related Articles | Metrics

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Feature Extraction and Modeling of Welding Quality Monitoring in Pulsed Gas Touch Argon Welding Based on Arc Voltage Signal ZHANG Zhi-fen* (张志芬), ZHONG Ji-yong (钟继勇), CHEN Yu-xi (陈玉喜), CHEN Shan-ben (陈善本) 2014, 19 (1):  11-16.  doi: 10.1007/s12204-014-1471-0 Abstract ( 737 )   Arc sensing plays a significant role in the control and monitoring of welding quality for aluminum alloy pulsed gas touch argon welding (GTAW). A method for online quality monitoring based on adaptive boosting algorithm is proposed through the analysis of acquired arc voltage signal. Two feature extraction algorithms were developed in time domain and frequency domain respectively to extract six statistic characteristic parameters before removing the pulse interference using the wavelet packet transform (WPT), based on which the Adaboost classification model is successfully established to evaluate and classify the welding quality into two classes and the classified accuracy of the model is as high as 98.81%. The Adaboost algorithm has been verified to be feasible in the online evaluation of welding quality. References | Related Articles | Metrics

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Behavior-Consistent Service Substitutions in Dynamic Environments CHEN Jun-qing* (陈俊清), HUANG Lin-peng (黄林鹏), YU Cheng-yuan (于程远) 2014, 19 (1):  17-27.  doi: 10.1007/s12204-014-1472-z Abstract ( 557 )   In this paper, a novel approach for service substitutions based on the service type in terms of its interface type and behavior semantics is proposed. In order to analyze and verify behavior-consistent service substitutions in dynamic environments, we first present a formal language to describe services from control-flow perspective, then introduce a type and effect system to infer conservative approximations of all possible behaviors of these services. The service behaviors are represented by concurrent behavior expressions (CBEs). Built upon the interpretation of CBEs, behavior-consistent service substitutions are defined and analyzed by subtyping technology. The correctness of the analysis approach is guaranteed by type safety theorem, which is mechanically proved in the Coq proof assistant. Finally, applications in web services show that our method is effective and feasible. References | Related Articles | Metrics

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Aesthetic Visual Style Assessment on Dunhuang Murals YANG Bing1 (杨 冰), XU Duan-qing1* (许端清), TANG Da-wei1 (唐大伟),YANG Xin2 (杨 鑫), ZHAO Lei1 (赵 磊) 2014, 19 (1):  28-34.  doi: 10.1007/s12204-014-1473-y Abstract ( 785 )   Dunhuang murals are gems of Chinese traditional art. This paper demonstrates a simple, yet powerful method to automatically identify the aesthetic visual style that lies in Dunhuang murals. Based on the art knowledge on Dunhuang murals, the method explicitly predicts some of possible image attributes that a human might use to understand the aesthetic visual style of a mural. These cues fall into three broad types:  composition attributes related to mural layout or configuration;  color attributes related to color types depicted;  brightness attributes related to bright conditions. We show that a classifier trained on these attributes can provide an efficient way to predict the aesthetic visual style of Dunhuang murals. References | Related Articles | Metrics

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Research of Underwater Self-Reconfigurable System WU Chao* (吴 超), GE Tong (葛 彤), ZHUANG Guang-jiao (庄广胶), LIU Jian-min (刘建民) 2014, 19 (1):  35-40.  doi: 10.1007/s12204-014-1474-x Abstract ( 687 )   This article describes a novel underwater robot, which is called underwater self-reconfigurable system (USS). USS is studied and developed by Shanghai Jiao Tong University. It is formed by a quantity of the same modules and works in group. Based on that, USS can change its form while working in the complicated underwater structures according to different tasks. New multi-jaw underwater docking system, piston style regulator and clamshell-like sampling module are designed for USS, these developments address the problems of underwater docking, floating condition adjusting and sampling. Besides, the gaits like wriggle, creeping, swimming and fourlegged moving have been successfully implemented in tank and lake test, which verifies the validity of the concept. References | Related Articles | Metrics

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Intelligent Video Surveillance for Checking Attendance of Traffic Controllers in Level Crossing XIANG Ke* (向 可), WANG Xuan-yin (王宣银), CAO Song-xiao (曹晓松), FU Xiao-jie (富晓杰) 2014, 19 (1):  41-49.  doi: 10.1007/s12204-013-1464-4 Abstract ( 559 )   This paper proposes a detecting and tracking scheme for automatic checking attendance of traffic controllers in level crossing by recognizing their warning waistcoats. Considering of the actual requirement of rapidity and validity, this paper employs techniques of motion detection, color segmentation and feature matching to deal with the challenging problems of illumination varying, light reflection and disturbance. Therefore, the task of distinguishing the target from candidates can be fulfilled accurately. Once a target being detected, the established color models are modified through learning color of the detected target, and then Cam-shift algorithm is employed to track this target smoothly. The experiments in real scenes demonstrate that this method has a great capability to detect and track traffic controllers in complex level crossing environment accurately, and the comparisons further demonstrate the validity of the proposed method. References | Related Articles | Metrics

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Ant Colony Optimization for Feature Selection in Software Product Lines WANG Ying-lin1,2* (王英林), PANG Jin-wei2 (庞金伟) 2014, 19 (1):  50-58.  doi: 10.1007/s12204-013-1468-0 Abstract ( 500 )   Software product lines (SPLs) are important software engineering techniques for creating a collection of similar software systems. Software products can be derived from SPLs quickly. The process of software product derivation can be modeled as feature selection optimization with resource constraints, which is a nondeterministic polynomial-time hard (NP-hard) problem. In this paper, we present an approach that using ant colony optimization to get an approximation solution of the problem in polynomial time. We evaluate our approach by comparing it to two important approximation techniques. One is filtered Cartesian flattening and modified heuristic (FCF+M-HEU) algorithm, the other is genetic algorithm for optimized feature selection (GAFES). The experimental results show that our approach performs 6% worse than FCF+M-HEU with reducing much running time. Meanwhile, it performs 10% better than GAFES with taking more time. References | Related Articles | Metrics

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Efficient Scheduling with Random Network Coding in Multi-Relay Wireless Network DING Liang-huia (丁良辉), BI Yanb (毕 琰), SUN Da-jiab (孙大佳),YANG Fengb* (杨 峰), QIAN Liangb (钱 良) 2014, 19 (1):  59-64.  doi: 10.1007/s12204-014-1475-9 Abstract ( 701 )   In this paper, we propose two novel efficient scheduling schemes with network coding in multi-relay wireless network to maximize the transmission efficiency. The first one uses adaptive forwarding with network coding (AF-NC), in which each relay adaptively calculates the number of packets having innovative information according to the feedback from the sink. With AF-NC, duplicate packets are not sent, and the total number of time slots needed to complete transmission can be significantly reduced. The second scheme, named adaptive forwarding with network coding and retransmission (AFR-NC), combines AF-NC with automatic repeat request (ARQ) to guarantee reliable end-to-end communication with limited resource occupation. Numerical results show that compared with simple forwarding with network coding (F-NC), AF-NC has close successful delivery rate with dramatically less time slots, while AFR-NC achieves strict reliability with limited resource cost. References | Related Articles | Metrics

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Surface Spline Interpolation Method for Thermal Reconstruction with Limited Sensor Data of Non-Uniform Placements WANG Ruo-lin (王若琳), LI Xin (李 鑫), LIU Wen-jiang (刘文江), LIU Tao* (刘 涛), RONG Meng-tian (戎蒙恬), ZHOU Liang (周 亮) 2014, 19 (1):  65-71.  doi: 10.1007/s12204-013-1469-z Abstract ( 650 )   With the characteristic size reducing as well as the power densities exponentially increasing, elevated chip temperatures are true limiters to the performance and reliability of integrated circuits. To address these thermal issues, it is essential to use a set of on-chip thermal sensors to monitor temperatures during operation. These temperature sampling results are then used by thermal management techniques to appropriately manage chip performance. In this paper, we propose a surface spline interpolation method to reconstruct the full thermal characterization of integrated circuits with non-uniform thermal sensor placements. We construct the thermal surface function using the mathematical tool of surface spline with the matrix calculation of the non-uniform sample data. Then, we take the coordinates of the points at grid locations into the surface function to get its temperature value so that we can reconstruct the full thermal signals. To evaluate the effectiveness of our method, we develop an experiment for reconstructing full thermal status of a 16-core processor. Experimental results show that our method outperforms the inverse distance weighting method based on dynamic Voronoi diagram and spectral analysis techniques both in the average absolute error metric and the hot spot absolute error metric with short enough runtime to meet the real-time process demand. Besides, our method still has the advantages such as its mathematical simplicity with no need of pre-process. References | Related Articles | Metrics

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Filter Bank Based Nonlocal Means for Denoising Magnetic Resonance Images GUO Tian-li (郭甜莉), LIU Qie-gen (刘且根), LUO Jian-hua* (骆建华) 2014, 19 (1):  72-78.  doi: 10.1007/s12204-014-1476-8 Abstract ( 774 )   Image denoising is a classical problem in image processing. Its essential goal is to preserve the image features and to reduce noise effectively. The nonlocal means (NL-means) filter is a successful approach proposed in recent years due to its patch similarity comparison. However, the accuracy of similarities in this algorithm degrades when it suffers from heavy noise. In this paper, we introduce feature similarities based on a multichannel filter into NL-means filter. The multi-bank based feature vectors of each pixel in the image are computed by convolving from various orientations and scales to Leung-Malik set (edge, bar and spot filters), and then the similarities based on this information are computed instead of pixel intensity. Experiments are carried out with Rician noise. The results demonstrate the superior performance of the proposed method. The wavelet-based method and traditional NL-means in term of both mean square error (MSE) and perceptual quality are compared with the proposed method, and structural similarity (SSIM) and quality index based on local variance (QILV) are given. References | Related Articles | Metrics

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Sequential Similarity Detection Algorithm Based on Image Edge Feature MA Guo-hong* (马国红), WANG Cong (王 聪), LIU Pei (刘 沛), ZHU Shu-lin (朱书林) 2014, 19 (1):  79-83.  doi: 10.1007/s12204-013-1465-3 Abstract ( 1007 )   This paper proposes a new sequential similarity detection algorithm (SSDA), which can overcome matching error caused by grayscale distortion; meanwhile, time consumption is much less than that of regular algorithms based on image feature. The algorithm adopts Sobel operator to deal with subgraph and template image, and regards the region which has maximum relevance as final result. In order to solve time-consuming problem existing in original algorithm, a coarse-to-fine matching method is put forward. Besides, the location correlation keeps updating and remains the minimum value in the whole scanning process, which can significantly decrease time consumption. Experiments show that the algorithm proposed in this article can not only overcome gray distortion, but also ensure accuracy. Time consumption is at least one time orders of magnitude shorter than that of primal algorithm. References | Related Articles | Metrics

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Optimal Posture Searching Algorithm on Mobile Welding Robot ZHANG Tao* (张 涛), CHEN Shan-ben (陈善本) 2014, 19 (1):  84-87.  doi: 10.1007/s12204-014-1477-7 Abstract ( 520 )   An independently developed mobile welding robot system is introduced. Kinematics model is the base of robot planning. With the Denavit-Hartenberg method, robot kinematics equation can be gotten. The robot welding torch inclination angle consists of the working and moving angles. According to the kinematics model, both the two angles and torch position can be calculated. Under special moving angle, a two-step algorithm is used to obtain the optimal manipulator posture. The calculation result shows that the algorithm has high precision. References | Related Articles | Metrics

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Research on Hydrogen Environment Fatigue Test System and Correlative Fatigue Test of Hydrogen Storage Vessel LI Rong1 (李 蓉), ZHENG Chuan-xiang1 (郑传祥), CHEN Bing-bing2* (陈冰冰), ZHOU Wei-wei1 (周威威), WANG Liang1 (王 亮) 2014, 19 (1):  88-94.  doi: 10.1007/s12204-013-1463-5 Abstract ( 646 )   A 70MPa hydrogen environment fatigue test system has been designed and applied in the manufacture of a hydrogen storage vessel. Key equipment is the 80MPa flat steel ribbon wound high pressure hydrogen storage vessel. A reasonable stress distribution has been realized, that is low stress in the liner of the pressure vessel and even stress in the flat ribbon layers. This optimal stress distribution is achieved through the adjustment of the prestress in flat steel ribbons. A control system for the fatigue test system has also been designed. It consists of a double control model, i.e. manual control and automatic control, to satisfy different experimental requirements. The system is the unique one that can be used in the real hydrogen environmental fatigue test system in China. An experiment for the 70MPa onboard composite material hydrogen vessel has been carried out on the system. The experimental result from this test is in close agreement with the practical operating conditions. References | Related Articles | Metrics

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Numerical Method on Load Sharing Problem of Thick Laminate Joints LIU Long-quan* (刘龙权), CHEN Kun-kun (陈昆昆), ZHANG Jun-qi (张俊琪), LIU Wu-xia (刘无瑕), WANG Hai (汪 海) 2014, 19 (1):  95-101.  doi: 10.1007/s12204-013-1466-2 Abstract ( 529 )   Accurately and efficiently predicting the load sharing of multi-bolt thick laminate joints is necessary to quicken the optimization of the large-scale structures over various design variables, and a two-dimensional (2D) finite element method (FEM) is introduced to meet such a demand. The deformation contributions of the joint zone are analyzed and calculated separately, including the shearing deformation of the fasteners shank, the bending deformation of the fasteners shank, and the bearing deformation of the fasteners and joint plates. These deformations are all transferred and incorporated into the components of the fastener’s flexibility. In the 2D finite element model, the flexibilities of the beam elements and bush elements are used to simulate different components of the fastener’s flexibility. The parameters of the beam elements which include the bending moment of inertia and intersection area, and the parameters of the bush elements which include the stiffness in different directions, are all obtained through equalizing the fasteners flexibilities. In addition, the secondary bending effect introduced by the single-lap joints is also taken into account to verify the flexibilities of the fasteners in practical application. The proposed FEM is testified to be more accurate than the traditional 2D FEMs and more efficient than the three-dimensional (3D) FEM in solving load sharing problem of multi-bolt single-lap thick laminate joints. With the increase of joint plates’ thickness, the advantages of the proposed method tend to be more obvious. The proposed 2D FEM is an effective tool for designing bolted joints in large-scale composite structures. References | Related Articles | Metrics

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Improving the Stab-Resistance Performance of Ultra High Molecular Weight Polyethylene Fabric Intercalated with Nano-Silica-Fluid GU Juan1 (顾 隽), HUANG Xian-cong2 (黄献聪), LI Yan2 (李焱), WANG Xin-ling1 (王新灵)，SHI Mei-wu2 (施楣梧), ZHENG Zhen1* (郑 震) 2014, 19 (1):  102-109.  doi: 10.1007/s12204-013-1467-1 Abstract ( 717 )   High performance fibers impregnated by shear thickening fluids (STFs) have been recognized as a kind of latent stab-resistant materials. In our work, the rheological properties of various nano-silica particles in different carriers were first investigated, some of which showed the typical characteristic of shear thickening phenomena. And then, the effects of add-on and surface hydrophilicity of silica particles, the type and concentration of the carriers were discussed in detail. It was found that the systems of hydrophilic silica in ethylene glycol, butylenes glycol and polyethylene glycol (PEG) demonstrated shear thickening; moreover, the reversibility of rheological behaviors of hydrophilic silica-PEG300 suspensions indicated energy dissipation existed within a circulation of shear stress. Furthermore, the detail mechanism of STF based nano-silica particles was explored and a process diagram was presented. Finally, the stab-resistance and morphology of cutting edge of ultra high molecular weight polyethylene (UHMWPE) fabric impregnated STF composites were investigated and the results were analyzed. The higher silica add-on was benefit to the improvement of the stab resistance of the composites. References | Related Articles | Metrics

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Automatic Wireless Power Supply System to Autonomous Underwater Vehicles by Means of Electromagnetic Coupler WANG Si-ling1* (王司令), SONG Bao-wei1 (宋保维), DUAN Gui-lin2 (段桂林), DU Xi-zhao3 (杜喜昭) 2014, 19 (1):  110-114.  doi: 10.1007/s12204-014-1478-6 Abstract ( 724 )   With the aim of sending electric power to autonomous underwater vehicles (AUVs), an automatic wireless power supply system by means of electromagnetic coupler was proposed. An equivalent circuit of the electromagnetic coupler with compensating capacitors was presented to analyze the performance of the system. The magnetizing inductance and leakage inductance, which are important for choosing compensating capacitors, were calculated by finite element analysis (FEA) methods. Then the voltage gain, power loss and system efficiency were analyzed to optimize the winding turns. Finally, a phase-shift full bridge zero-voltage-switching converter and an electromagnetic coupler were produced. The experimental results demonstrated that the proposed system has a high voltage gain with small variation and sufficient power feeding. References | Related Articles | Metrics

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An Enhanced Safe Distance Car-Following Model YANG Da1,2,3* (杨 达), ZHU Li-ling1 (祝俪菱), YU Dan1 (于 丹)，YANG Fei1,2 (杨 飞), PU Yun1 (蒲 云) 2014, 19 (1):  115-122.  doi: 10.1007/s12204-014-1479-5 Abstract ( 675 )   Gipps’ model, a well-known safe distance car-following model, has a very strict restriction on the car-following behavior that the following vehicle has to maintain the exact safe distance to the leading vehicle to avoid rear crash. However, this restriction is not consistent with the real traffic condition. Due to that, an enhanced safe distance car-following model is proposed first, and then calibrated and evaluated using the field data. Furthermore, the simulation is conducted to analyze the characteristics of the new model. The results of evaluation and simulation illustrate that the proposed model has higher simulation accuracy than the original Gipps’ model, and can reproduce the stable flow and shock wave phenomena that are very common in real traffic. Moreover, the simulation results also prove that the enhanced model can better stabilize the traffic flow than Gipps’ model. References | Related Articles | Metrics

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Equivalent Stochastic Linearization for Nonlinear Uncertain Structure Under Stationary Gaussian Stochastic Excitation LIU Yong* (刘 勇), CHEN Lu-yun (陈炉云), YI Hong (易 宏) 2014, 19 (1):  123-128.  doi: 10.1007/s12204-014-1480-z Abstract ( 571 )   Equivalent stochastic linearization (ESL) for nonlinear uncertain structure under stationary stochastic excitation is presented. There are two parts of difference between the original system and equivalent system: one is caused by the difference between the means of original and equivalent stochastic structure; and another is caused by the difference between the original and equivalent stochastic structure which has the relation with stochastic variables. Statistical characteristics of equivalent stochastic structure can be obtained in accordance with mean square criterion, so nonlinear stochastic structure is transformed into linear stochastic structure. In order to attain that objective, the compound response spectrum of linear stochastic structure under stationary random excitation which is used in the solution is derived in the case of the mutual independence between stochastic excitation and stochastic structure. Finally, the example shows the accuracy and validity of the proposed method. References | Related Articles | Metrics