Table of Content

25 November 2017, Volume 28 Issue 22

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Control Algorithm of Active Head Restraints Based on Moving Window Specific Power

YAN Lingbo1;ZHU Zhipeng1;WANG Kai2;CAO Libo1

2017, 28(22):  2647-2654. 

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An active head restraint controlled by the acceleration signals was developed to reduce occupant injury in the rear-end impacts. Aiming at the control systems of the restraint, a moving window specific power algorithm was proposed. Its anti-jamming and trigger timeliness were analyzed by comparing operational data with moving window integration algorithm and specific power algorithm respectively, and several tests including head restraint bench tests and rear impact sled tests were conducted. The results show that the algorithm has a robust anti-interference and a timely trigger, its trigger time error is within 1ms, and that false triggering may be avoided effectively. The control system may send out the control signals within 15ms, and that the head restraint may be fully expanded 52ms after the collision.

Modeling and Experimental Study of Inter-electrode Gaps in ECM for Planes of Floating Cathode with a Round Mouth

PANG Guibing 1;XIN Kaikai 1;CAI Xiao1;JI Tian1;ZHANG Liping1;LIU Jiyu2;HAN Jiwan3

2017, 28(22):  2655-2661. 

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A new machining approach was proposed using electrolyte film to support the floating cathodes to form the machining inter-electrode gaps, whose regulation and control were realized by adjusting the flows and currents. Taking ECM of floating cathodes with round mouths as an example, a mathematic model of the machining gaps was established on the basis of fluid mechanics and electrode process kinetic theory, and the relationships among gaps, flows, pressure differences and currents were acquired. By analyzing characteristics of the gap flow fields using the software Fluent, the distributions of pressure fields and velocity fields of the electrolyte in the gaps were established, and pressure differences between the inlets and outlets, and the flow rates of the outlets were obtained. Additionally, different machining gaps under dissimilar flow and current circumstances were acquired by experiments. The results and variation characteristics of the theoretical model and the experiments are similar to each other.

Prediction Model of Superheater Tube Wall Temperatures Based on Grey System

XU Hong1;DENG Bo1;JIANG Dongfang2;GUO Peng1;NI Yongzhong1

2017, 28(22):  2662-2668. 

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A grey model was established for forecasting the temperatures in the inlet and outlet sections of superheater tubes in power plants, based on the external furnace temperature data. Combined with the finite volume method, the temperature distribution of the single tube wall was calculated. The real measured data of final superheater were used as inputs of the prediction model to analyze the prediction accuracy under three conditions. Results show that the accuracy exceeds 99%. Under the running conditions, the calculated errors of temperature of single tube wall are less than 2.9℃. The model may predict and calculate the variation of tube temperature accurately, and has good guiding significances for the safety operation in power plants.

Effects of Large-bore Gas-fuelled Engine with Elbow Connected to Gas Injection Device on Mixing Performance

WANG Tianbo;CHANG Siqin;LIU Liang

2017, 28(22):  2668-2674. 

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Gas fuel was induced to the helical intake port and the tangential intake port of a large-bore port fuel injection engine separately by elbow connected to the outlet of gas fuel injection device(GID). The transient computational fluid dynamics(CFD) engine model incorporating the GID’s motions was established to analyze the effects of injection location on the in-cylinder mixing processes. The results indicate that the intake flow of two adjacent intake ports, the helical intake port and the tangential intake port will interfere with each other near the cylinder head during the intake stroke. For the helical port injection case, the gas fuel approaches to the cylinder center and concentrate on the cylinder head near the end of the compression stroke; while for the tangential port injection case, the gas fuel flows to the piston top and concentrate on the piston top near the end of the compression stroke. At ignition time, the helical port injection case shows best in-cylinder mixing performance, while the tangential port injection case is the worst.

Transmission Accuracy Quantitative Distribution of Biaxial Rotary Milling Heads Based on Sensitivity Weights

WU Fenghe;LI Yongxin;LI Shuzhi;LI Shaohui

2017, 28(22):  2675-2680,2688. 

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A biaxial rotary milling head with planetary gear reducer possessed complicated transmission systems and multiple transmission errors, which might cause difficulties in the transmission accuracy distribution. A new method of accuracy quantitative distribution was proposed based on sensitivity analysis and proportional weight method. Firstly, the transmission chain error model of the biaxial rotary milling heads was established and the total transmission errors were determined by the positioning accuracy requirements and transmission error analysis. Then, the errors which had greater influence on the transmission accuracy were filtered by sensitivity values. At last, the normalized weighted method was applied to distribute proportionally the errors with larger sensitivity to meet the requirements of accuracy design. And sixteen feasible error distribution schemes were gotten. The method has clear physical expression, high maneuverability and improves the accuracy design efficiency, which may lay a foundation for the accuracy distribution of the complex systems with multiple error factors.

Tool Path Planning Algorithm of Five-axis Machining Based on Directional Distance Theory

YIN Yexi1,2;QIN Hengfeng1;ZHOU Houming1

2017, 28(22):  2681-2688. 

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For the residual error problems of five-axis machining free-form surface of toroidal cutter, a tool path planning algorithm with maximum ISO-scallop due to directional distance theory was proposed based on traditional ISO-scallop algorithm. Firstly, the initial lateral spacing distance of the known cutter contact (CC) point was calculated according to differential geometry theory, and the adjacent CC point was obtained in lateral direction. And then the actual scallop height of the adjacent CC point was calculated by scallop error calculation model based on the directional distance theory. Finally, the maximum ISO-scallop of the adjacent tool path was planned through the iterative calculation. Repetitions went on until the tool paths of the whole surface were obtained. The experimental results show that compared with the commercial software MasterCAM 9.0, the algorithm may greatly reduce total length of tool paths while ensuring the quality of surface machining, and improving the processing efficiency.

Fault Diagnosis for SBW Systems of Unmanned Vehicles

XIONG Lu1,2;FU Zhiqiang2;LI Zengliang2;ZHANG Renxie1

2017, 28(22):  2689-2694,2700. 

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In order to ensure the safety and reliability of SBW systems for unmanned vehicles, the structures, working principles and malfunctions of SBW were analyzed. Using discrete dynamics model and 2-DOF vehicle model, with yaw rate signals, lateral acceleration signals and the current signals of steering motor, a real-time fault diagnose algorithm was designed based on Kalman filter method for steering tube column corner sensor, and through real-time estimation of motor parameters on abrupt faults to diagnose real-time faults of the motor. Real vehicle test results show the fault diagnose algorithm proposed herein may timely and accurately diagnose the failures of SBW systems.

Energy Management Strategy Based on Type Recognition and Multivariate Nonlinear Regression Optimization

SUN Lei1;LIN Xinyou2;LIN Guofa3

2017, 28(22):  2695-2700. 

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The type recognition algorithm of driving conditions was studied based on LVQ neural network，to provide the basis for the intelligent management strategy of hybrid electric vehicles. First, 11 characteristic parameters were extracted from 4 typical road type conditions and the 3 kinds of standard cycle conditions to train the data. Then, the LVQ neural network type recognition algorithm of driving condition was developed. Based on this, a hybrid power system was as an example, which combined with multiple nonlinear regression analysis to develop the corresponding control strategy. Finally, LVQ neural network type recognition simulation model of driving condition was established based on the Simulink simulation platform, type recognition tests were carried on under the Chinese city typical cycle road conditions, standard condition recognition tests were carried on by constructing UDDS+NYCC+UDDS driving conditions. The results show that the established LVQ neural network may accurately identify the type of driving condition types and the control effectiveness of the energy management strategy is improved effectively.

Modeling and Experimental Analysis of an Active Anti-roll System

HUANG Kang;PAN Yi;ZHAO Ping

2017, 28(22):  2701-2706,2731. 

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A dynamics model of automotive active anti-roll bar system was proposed to improve the vehicle's driving stability. A PID roll stability controller was designed by establishing auto active defense tilting lever model in the MATLAB/Simulink environment, and the automobile dynamics model was established in CarSim, and the simulation of the system was realized by MATLAB/Simulink and CarSim. The simulation results indicate that the active anti-roll bar system may significantly reduce the roll angles of vehicle body compared with common anti-roll bar. The road tests were also processed, which verified the simulation and approves that the automotive active anti-roll bar system may effectively improve the vehicle's driving stability and safety, as well as the riding comfort.

An Improved Dynamics Parameter Identification Method for SCARA Robots

YAN Hao1;BAI Ruilin1;JI Feng2

2017, 28(22):  2707-2713. 

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In order to identify the dynamics parameters of SCARA robots, a new identification method was proposed based on improved Fourier series. According to the complete dynamics equations of the SCARA robots, a linear form of the dynamics model was derived. The improved Fourier series was used as the excitation trajectory of the robot joints, and the joint angles satisfied the continuous periodicity, and the angular velocities and angular accelerations were as zero at the beginning and end of the trajectory. In order to further improve the identification accuracy, the condition numbers of the observation matrix of the SCARA robots were used as the objective function, and based on crowding mechanism the niche genetic algorithm was used to optimize the coefficients of the trajectory. Considering the influences of measurement noises, the weighted least square method (WLS) was used as the parameter estimation method. The experimental results show that the proposed method may accurately identify the dynamics parameters of the SCARA robots, torque measurements and predictive values of two joints, the residual root mean square values are reduced by 11.50% and 26.35% respectively.

Feature Extraction and Correlation Model Construction of Online Product Reviews and Its Applications

YU Qiwei1;IAO Ying1;IN Jing1;U Xinsheng1;ANG Qinglin1;HANG Fei2

2017, 28(22):  2714-2721. 

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Online product reviews were the feedback of customer valuing a product. It was an urgent problem for manufacturers and retailers to mine valuable informations effectively and timely from online product reviews with the goal of gaining competitive advantages. Considering comprehensive factors such as word, part-of-speech (POS), dependency relations, governing word and its opinion description, the unit of rule for extracting product features and the rule template were designed. Product features were extracted from online reviews effectively through conditional random field (CRF) theory, and the product features were classified. The quantitative calculation models of product features including frequency and sentiment score were proposed. A correlation model among product features was established based on the description contents of product features and their classifications. On the basis of these, an approach of inferring the key influence factors among product features was presented based on Bayes network. Finally, a case study was performed to verify the feasibility of the methods mentioned above by using a mobile phone as an example, and the results may be used as evidence to implement precision management for manufacturers and retailers.

Study on Multi-resource Intercellular Scheduling Problem Based on ASS Algorithm

FAN Jiajing1;CAO Yuhua1;CAO Min2

2017, 28(22):  2722-2731. 

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An intercellular scheduling problem based on multi-resource constraint was put forward considering the characteristics and important roles of equipment, human resources and AGVs in cellular manufacturing system. Aiming at minimum sum of part late delivery times, the numbers of employee and intercellular moving times and the numbers of AGV, a goal programming mathematical model was built. An ASS algorithm was presented to solve this model according to the model particularity. In the ASS algorithm, a genetic algorithm was used to get the new solution sets and the pattern search(PS) was used to improve the reference solution sets to enhance the rate of convergence. The mathematical model and algorithm were applied into 8 different size examples to prove validity of the model and algorithm. At last, the interactions of equipment, human resource and AGV were explained based on the analyses of the examples.

Dynamics Coupling Analysis of Flexible Underactuated Manipulators

LIU Jianying;WANG Xiaoyue;GONG Jinliang

2017, 28(22):  2732-2737,2746. 

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To establish flexible 3R underactuated manipulator dynamics equations, Euler-Bernoulli beam model was used with boundary conditions of iterative computations, the flexible robotic arm was coupled with the dynamics simulation. Based on the flexible manipulator modal analyses, the flexible manipulator was regarded as cantilever arm and simply supported free beam model with boundary conditions. A dynamics model of flexible 3R underactuated manipulators was established by assumed mode method. Simulation results show that the addition of boundary conditions for the iterative calculations of the flexible beam model may get a better reflection of the coupling accelerations of freedom joints. Finally, the coupling underactuated indices of flexible and rigid underactuated manipulators were analyzed. The results reveal that the flexible manipulator joints contain more complex coupling situations. The key to control underactuated flexible manipulators is to control the elastic vibrations of flexible manipulators.

Product Quotation Method Based on Three-dimensional Geometric Features

DONG Yude1;MI Dengbin1;CHEN Minglong1;SU Fang1;SHI Xiaolei2;YANG Shanwen2;TAO Gaozhou2

2017, 28(22):  2738-2746. 

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A product quotation method was proposed based on 3D geometric features, which utilized researches about the automatic feature recognition and the second development of CAD, aiming at solving problems of  high demands on timeliness and diversity of product cases and low efficiency in responding quotations of product example bases in current mainstream quotation systems. First, the common design features were classified, and the mapping relations of machining features, design features and their marks were established. The identification of the design features was accomplished by using the one-to-one image relationship among the feature signs and the design features. The identification of the machining features was realized by combining the image relationship among the design features and the machining features. Secondly, the parts' quotations were studied through the material costs and processing costs, a product quotation model was established by synthesizing the hierarchy of products, components and parts. Thirdly, in order to respond quickly to the individual needs of users, a service model was established from user demands to product configurations to rapid response quotation.Finally, a quotation system was developed based on 3D geometric features of Creo, and applied to an enterprise's high power inverter quotation, which improves the product quotation efficiency and verifies the feasibility of the quotation method based on the 3D geometric features.

Research on MEMS Micro-motion Measurements Based on Diamond Search Block-matching Technology

GONG Lixiong1;CHENG Shuangsheng2;LIU Yong3

2017, 28(22):  2747-2752. 

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Firstly, the model of block-matching motion and measurement principles were analyzed, and the algorithm of diamond search-based block-matching path search was established using the minimum sum of absolute difference(MSAD) to set block-matching criterion. The algorithm of diamond search-based block-matching located roughly or precisely by large diamond search pattern (LDSP) or small diamond search pattern (SDSP), and to compute the best motion vector of micro-motion. Next, MEMS image acquisition programme of computer micro-vision was designed, and 24 resonators image of different phase were analyzed and tested by the proposed micro-motion measurement method. The results show that block-matching technology based on MSAD and diamond search algorithm may well estimate and measure micro-motion vectors of MEMS devices.

Permutation Flow Shop Scheduling Problem Based on Hybrid Binary Distribution Estimation Algorithm

PEI Xiaobing;ZHAO Heng

2017, 28(22):  2752-2759. 

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To solve the permutation flow shop scheduling problems with the objective of minimizing makespan, an effective new hybrid binary estimation distribution algorithm（HB-EDA） was proposed based on binary estimation of distribution algorithm and BBO. HB-EDA took distribution estimation algorithm as architecture and the binary probability model was used as the evolutionary basis. For the excellent chromosomes and the inferior chromosomes, the link gene blocks with the dominant informations and the disadvantage informations were excavated by the probability model, these blocks were reserved in two archives for future use. Integrating with migration operator of BBO, two block archives were used to update maternal chromosomes with certain migration rate to generate sub-groups, then performing segmentation and recombination on the chromosomes to further selecting high fitness solution. Simulation results on Reeves and Taillard suites and comparisons with other algorithms validate the excellent searching ability and efficiency of the proposed algorithm.

Study on Wall Thickness Prediction Accuracy by Sine Law for Incrementally Formed Conical Parts

CHEN Jiping;QIAN Jianqing;WANG Huiting

2017, 28(22):  2760-2766. 

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The wall thickness variations of aluminium conical parts were analyzed during incremental forming with different processing parameters. The application scope and accuracy of wall thickness variation by the sine law for incrementally formed aluminium conical parts was studied through comparing the variations and differences of measured wall thicknesses for different processing parameters with the values predicted by the sine law. The results show that the wall thickness variations of conical parts during incremental forming have three stages, i.e. wall thickness thinning stage, wall thickness pick-up stage and wall thickness stable stage. The extremely easy rupture points of sheet metal are “the minimum value points” between the thinning regions and pick-up areas. Through comparing the measured and the predicted wall thickness values, it is found that the wall thickness measured in the stable region is close mostly to the predicted wall thickness values of sine law. The application scopes of wall thickness variation sine law for incrementally formed aluminium conical parts are in the stable regions. Work hardening produced in the primary processing may result in difficult deformations at joints of the sheet metals in secondary processing with higher average error rates. Most measured wall thicknesses in the stable regions for incrementally formed conical parts are 1%~2% lower than the predicted values of sine law. The feed amounts have greater influences on the accuracy of sine law. Furthermore, the wall thickness empirical equations of the wall thickness thinning region, pick-up area and stable region for conical parts were established through Levenberg-Marquardt algorithm and global optimization calculating methods.

Study on Laser Milling Process Parameters for Sides of Laser Cladding Parts

SHI Keming;YANG Guilin;WANG Mingdi;DU Qiu

2017, 28(22):  2766-2771. 

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In order to improve the quality of cladding parts, a method of laser milling was adopted herein to obtain smooth and flat plains of cladding parts. The technology of flank milling process of cladding parts was researched, and point space, laser power, pulse duration and defocusing amount were chosen as variables. The weight and optimization of process parameters were researched by orthogonal experiments. Then the optimized parameters were used to process cladding parts, milling width 0.075mm and surface roughness 2.319μm were obtained. Compared with original cladding parts, the qualities of processed parts are better apparently, which proves the feasibility of improving surface quality by laser milling.