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Table of Content

    10 February 2016, Volume 27 Issue 03
    Variability of Temperature-sensitive Points and Its Influences for CNC Machine Tools
    Miao Enming, Liu Yi, Gao Zenghan, Liu Hui
    2016, 27(03):  285-289,322. 
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    In thermal error compensation technology on CNC machine tools, the core issue was to establish mathematical model which might reflect the relationship between incremental temperature and thermal errors of the machine, and the accuracy and robustness of model depended on whether model's independent variables could reflect the temperature field distribution of CNC accurately, in other words, whether the temperature-sensitive points were accurate and stable. The variability of temperature-sensitive points was proved by analyzing batches of experimental data of air cutting experiments on Leaderway-V450 machine tool spindle Z direction, so it changed the degree of multi-collinearity among temperature variables, caused a serious impact on model's forecasting accuracy and robustness. Since PCR algorithm might eliminate the influences of multi-collinearity among variables, the modeling method was proposed based on PCR algorithm. And this method was used to practice tests through the experiments of actual machine. The results show, PCR model reduces the effects of changes in temperature-sensitive points on model's forecasting accuracy significantly, and the model has good forecasting accuracy and robustness.

    Dynamic Load Calculation and Statistical Analysis of Gear Transmission System of Wind Turbine under Stochastic Wind Loading
    Xu Fang, Zhou Zhigang
    2016, 27(03):  290-295. 
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    Aiming at the problems of high failure rate of wind turbines gear transmission system under the stochastic wind speed conditions, a dynamics model of gear transmission system coupled with bearing of wind turbine was established on the basis of simulating real wind speed, and the external random wind load and internal excitations such as time-varying mesh stiffness of gear pair, time-varying stiffness of rolling element bearings and integrated transmission errors were considered in the model. Numerical method was used to simulate the dynamics model, the dynamic meshing forces of each gear pair as well as the dynamic contact forces of each bearing were obtained. Then, the stress spectrum and the probability distribution function of the loads acting on the key parts of transmission system were obtained by statistic the stress-time history curves which was obtained by using the finite element method and the Hertz contact theory. This research results lay a foundation for dynamic reliability analysis and fatigue life prediction of the gear transmission system of a wind turbine.

    Dynamic Property Analysis of HSK Spindle-toolholder System Based on Joint Part
    Chen Jian, Wang Guicheng, Tian Liang , Shen Chungen, Zheng Dengsheng
    2016, 27(03):  296-301. 
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    The HSK spindle-toolholder FEM was modeled and the  stiffness and damp parameters of joint part were  identified with elastic theory and damp theory.The HSK spindle-toolholder system could be divided into three parts,such as HSK spindle,spindle-toolholder joint part and toolholder. HSK spindle and toolholder could be simplified as Timoshenko beam, and the FRF could be gained with receptance coupling theory.The spindle-toolholder joint part might  be  simplified as spring-damp model,and the FRF could  be achieved with multi-points receptance coupling theory. Then the FRF of system  was gained with rigid coupling theory.The spindle-toolholder was treated as rigid connection,five-points connection and seven-points connection,and the tip-point FRFs of system were computed.At last, comparing these FRFs with experimental FRF, some results may  be obtained.

    Modeling and Verification on Cutting Load Dynamics of Band Saw
    Ni Jing, Li Lu, Xu Jing, Wu Can
    2016, 27(03):  302-307,314. 
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    According to the problems that the existing models on cutting load characteristics of band sawing process could not predict the dynamic characteristics, the cutting load characteristics was studied by dividing into steady state characteristics and the dynamic characteristics herein. Firstly, the single sawtooth cutting load model of steady state characteristics under the conditions of equal tooth pitch was built by introducing the cutting and scraping coexist principle and inclined sawtooth equivalent principle. Furthermore, the dynamic characteristics of cutting load was optimized by introducing micro-displacement equivalent principle during the feeding process. Finally, the cycle characteristics of a set of sawtooth and bandsaw transmission was introduced, and the single tooth cutting load dynamic model was proposed under the conditions of variable tooth pitch. Comparison of simulation and experimental results shows that the cycle characteristics of the single tooth, a set of tooth and bandsaw transmission coincide with the experimental results. The error of three important frequencies between simulation and experimental results is less than 4%. Therefore, the proposed model can better predict the actual cutting load characteristics.

    Research on Hardened 42CrMo Saw-tooth Chip by Trial with Spring Type Quick-stop Device
    Qing Zhenhua, Zuo Dunwen, Yang Haidong, Lei Xiaobao, Xu Feng
    2016, 27(03):  308-314. 
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    Saw-tooth chip formation process was trial researched herein, on hard cutting of medium-carbon alloy structure 42CrMo(52HRC) high strength steel. Tool rod motion trajectory of QSD was recorded by a high-speed camera, the QSD's performance was quantitatively analyzed by calculating the velocity and acceleration. Orthogonal cutting QSD trial of disc sample was carried on lathe by cutting with different parameters, chip roots received were made into metallographic specimen; crack initiation, crack propagation and the adiabatic shear band at the stage of saw-tooth chip forming period were studied, saw-tooth chip forming process was also analyzed by observing the “breezed” cutting area. The results show that: crack initiation can be observed at the free surface, crack propagation expandes to cutting zone and eventually leads to the chip separation; the saw-tooth chip formation process of hard cutting high strength steel 42CrMo can be divided into four stages.

    Study on Type Synthesis Analytical Method of Variable Power Transmission Mechanism
    Di Liming, Zhao Yongsheng, Du Danyang
    2016, 27(03):  315-322. 
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    Based on the function requirements of variable-cycle engine (VCE) mode switching, a type synthesis design analysis method of power transmission mechanism with variable phase and transmission ratio was proposed. A universal driving mechanism with double row planetary gear train (DRPGT) was firstly designed, and the phase and transmission ratio could be adjusted at the same time. Secondly, a series of the mechanism schemes with similar structures and functions were obtained by configuration design and topology analysis, the rough set theory was combined with cluster analysis to carry on the research of classification and type synthesis. Finally, a kind of series driving mechanism scheme with DRPGT was obtained, where the front row had one planet gear each group between the gear ring and sun gear, and the rear row had two outer gearing planet gears each group. This kind of scheme can meet the mode switching demands of VCE, and can interrupt the power transmission in case of emergency. Research results indicate that the design analysis method which is applied to classification and type synthesis of mechanism schemes is efficient.

    Analyses of Natural Characteristics and Sensitivity for Torsional Vibration of RV Reducer
    Liu Baixi, Wang Wenjun, Nie Songhui
    2016, 27(03):  323-327. 
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    Taking the RV reducer as the research object, and considering the influences of the system stiffness and the eccentric angle of cycloid gear on torsional vibration characteristics, a 13 DOF modified torsional dynamics model was established by lumped-parameter method. The impacts of cycloid gear eccentric angle on the natural frequency were analyzed by calculating the natural frequency and corresponding modal shapes of the system. Using the partial derivative method, the sensitivity of natural frequency to moment of inertia and stiffness was calculated. The results show that the key factor influencing the natural frequency is the bearing stiffness.

    Dynamic Simulation for a Three-arm Robot on Orbit
    Huang Jinying, Du Weimin, Li Hui, Jiang Zhihong, Yang Huan
    2016, 27(03):  328-333. 
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    A simplified robot model with three arms was designed according to the needs of space operations. The coordinate transformation matrix was established based on the D-H method and the kinematic  equations of the robot were derived. Based on ADAMS virtual prototyping technology, the climbing process of the robot on a pole was simulated for three kinds of gravity, respectively. The force curves and effect factors were obtained so as to offer the design references for the robot. 

    Research on Surface Integrated Processing System for Shell Maintenance
    Zhang Huaizhi, Zhao Daxing, Zhang Yingjiang, Xie Junlei, Cao Hong'an, Xie Quan
    2016, 27(03):  334-337. 
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    In order to solve the artillery maintenance manual skim backward technology, low efficiency and poor quality problem, a shell surface integrated processing system was developed. In view of the main technical requirements of artillery maintenance, a kind of shell surface automation integrated processing system design scheme was put forward, the multi-function shell surface treatment agent, automatic spray equipment, automatic transmission device, infrared drying device, the design and performance of the automatic control system were introduced, and the action principles and action reliability of the processing system were analyzed . Experimental results show that the system is of high degree of automation, it is suitable for projectiles, safe and reliable, which can realize the “shell surface degreasing, derusting, phosphating, passivation” comprehensive processing.

    Blind Source Separation Based on Wavelet Semi-soft Threshold Denoising
    Meng Zong, Ma Zhao, Liu Dong, Li Jing
    2016, 27(03):  337-342. 
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    In order to extract fault feature informations from the mechanical malfunction signals with noise, a method of blind source separation was proposed based on wavelet semi-soft threshold denoising. First, wavelet semi-soft threshold was used to filter the failure signals. Then, joint approximate diagonalization was used as blind source separation method to separate signals. Pretreatment was often not enough to eliminate all noises, therefore, it was necessary to denoise again to improve the separation performance. Finally, the feasibility and validity of this method was verified by experiments.

    Waveform Curvature Extension in Applications of Local Mean Decomposition
    Wei Yonghe, Niu Baoguo, Liu Xueli, Zhao Xuning
    2016, 27(03):  343-348,354. 
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    LMD was a kind of signal processing method to self-adaptively decompose the complex amplitude modulation-frequency modulation signals into a series of single-component amplitude modulation-frequency modulation. To some degrees, the decomposition results were of distortions because of the influences of end effects. In order to improve the end effects from LMD, the data segments which were most similar to wave boundary data segments were searched according to the curvature fluctuations of characteristic waves. The waveform curvature was applied in LMD. According to the comparison of mirror extension and self-adaptive waveform match, the advantages of waveform curvature extension were verified. The experiments of simulation signals and actual gear failure were made, the results show that this method can suppress the end effect effectively and improve the decomposition precision.

    Vibration Signal Feature Extraction and State Recognition for Worm Reducer
    Bai Guozhen, Zhou Haining
    2016, 27(03):  349-354. 
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    To achieve state recognition of worm reducer running state, a method of constructing wavelet packet energy matrix was proposed firstly based on reference signal. This was done by combining the characteristics of wavelet packet decomposition and matrix theory. It analyzed the intrinsic physical relationship between the maximum singular value (eigenvalue) and operating conditions. The results validate that the feature parameters extracted by this method is more sensitive than that by conventional ways. Secondly, the MEA was improved to optimize BP neural network. The fault characteristic parameters were extracted as the input feature vectors of neural network to realize the recognition of worm gear reducer states. The experimental results show that correct diagnosis rate increases 17.93 percent, which indicates the superiority of improved algorithm. A fast classification method was presented, which can solve the problems of on-line diagnosis for real-time requirements by distinguishing between normal and failure states well.

    A New Shakedown Numerical Analysis Method for Huge Complex Strcuture and Its Applications
    Zou Zongyuan, Guo Baofeng, Jin Miao, Mao Chunyan
    2016, 27(03):  355-360. 
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    The local high stresses appeared commonly in a loaded huge complex structure. Some of them were usually close to or even exceed the material yield strength due to the restrictions of the geometric size and the practical manufacture. It was troublesome with the applications of the conventional elastic strength design rule. The elastic-plastic shakedown design rule might utilize the plastic bearing capacity of material, then to solve this kind of strength problem well. Thus the shakedown theorem was introduced, and based on Melan shakedown theorem, a self-equilibrium stress field was constructed by subtractting the elastic-plastic stress field and the elastic reference stress field of the peak load, and the corresponding shakedown condition was derived. Then with the applications of the elastic-plastic incremental finite element technique, the loading-unloading calculations for different load levels were conducted to obtain the residual stress fields. Taking consideration of the relation between the residual stress field and the constructed self-equilibrium stress field, the shakedown limit load was determined by the shakedown conditions. Then a shakedown numerical analysis method for huge complex structure was established. The shakedown analysis for the main hydraulic cylinder of a 125MN forging hydraulic press was performed by this new method.

    Control Strategy of Shearer Automatic Height Adjusting Based on Adaptive Fuzzy Sliding-mode Variable Structure
    Mao Jun, Yang Zhenhua, Pan Dewen
    2016, 27(03):  360-364. 
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    Owing to the problems of automatic height adjusting of shearer and mining coal working surface unmanned, control system of adaptive fuzzy sliding-mode variable structure was put forward, which was based on electro-hydraulic position servo system. The conditions of the shearer automatic height adjusting were analyzed. By establishing mathematical model of the shearer height adjusting system, the control variables of the shearer height adjusting system were gained. An automatic height adjusting controller that adopted the adaptive fuzzy sliding-mode variable structure control strategy was designed, and its stability was analyzed. MATLAB was used for automatic height adjusting controller simulation. The results show that the control system of adaptive fuzzy sliding mode variable structure achieves accurate tracking of shearer cutting along a predetermined trajectory. Compared with the PID control technology, the tracking error is small, and the control effect is ideal.

    Research on Kinetics Characteristics of Needle in GDI Injector
    Kong Xiangdong, Zhang Zhendong, Wang Xiaoyan, Cheng Qiang
    2016, 27(03):  365-369. 
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    Kinetics behaviors of the needle had an important impact on stability and reliability of the GDI injector. With a GDI injector as the object, this paper established a kinetics model of the needle and an AMESim simulation model of the GDI injector based on mechanical characteristics in order to reveal the influence mechanism of different parameters. The paper analyzed influence rules of different parameters through simulation, the results show that reducing seat cone angle appropriate, increasing contact area between ball and needle, and reducing moving mass of the needle can suppress the amplitude of oscillation effectively. The paper proposed a comprehensively improved structure based on above analyses of the GDI injector. The final results show that kinetics characteristics of the needle can be improved significantly with the optimized new structure.

    Modelling and Analysis of 6-RUS Parallel Mechanism of Image Compensation of Satellite Camera
    Zhao Yanzhi, Zhao Fei, Yang Jiantao, Li Xingxing, Zhao Tieshi,
    2016, 27(03):  369-375. 
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    A parallel 6-RUS mechanism was used as the compensation platform for image motion which was caused by the multi-dimensional motion of the satellite. Based on influence coefficient theory, the kinematics model of this mechanism was built by velocity screw and acceleration screw. The dynamics model of this parallel platform in non-inertial frame was developed taking advantage of Newton-Euler's equation based on screw theory, and then the influence of the motion of the non-inertial frame on input of the mechanism in the whole working space was analysed. This mechanism modeling method was simplified with screw using coordinate-invariant in the non-inertial system.

    Reliability Modeling and Analysis for Process System of Sheet Metal Assembly
    Wen Zejun, Liu Jijun, Zhao Yanming, Hu Zhongju, Liu Zhan, Chen Lifeng
    2016, 27(03):  376-382. 
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    A product quality oriented reliability modeling method was developed containing pin/hole (slot) tolerance for process system of sheet metal assembly. Firstly, considering locating pin tolerance, part hole (slot) tolerance and pin wear, a statistics feature model of assembly deviation was presented. Then the locating pin wear model was deduced and analyzed, according to analyze the relationship between assembly qualities and process system reliability, and considering the impacts of locating failures rate and process wear on the process system reliability, the structure reliability model and assembly quality oriented reliability model of process system were built, then the process system reliability modeling method was formed. An automotive body side panel assembly was given as an example, the assembly process system reliability was analyzed based on the modeling method. The results show that locating pin wear, fixture layout and tolerance of pin/hole (slot) are important factors that affect process system reliability of automotive body side assembly. The method provides a new way of process system reliability analyses for product assembly. 

    Study on Parallel Computing Methods for Aero Engine Fan Blade off Simulation Analyses
    Hou Liang, Zhang Xiaoyun, Wang Zhiqiang, Chai Xianghai,
    2016, 27(03):  383-386. 
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    To solve the numerical simulation problem of fan blade off in aero engine, the effects of parallel mode and grid domain decomposition strategy on computing efficiency and consistence were analyzed herein. An optimal strategy for domain decomposition and parallel mode configuration was proposed to satisfy the computation consistency requirements. The superiority of the strategy was verified by a practical engineering case.

    Optimized Design and Kinematic Analysis of Clamping Mechanism for Trimming Robot
    Li Fengping, Zhang Zhengya, Zhou Sijia
    2016, 27(03):  387-390,412. 
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    The optimum design of clamping mechanism for a trimming robot was conducted herein.The optimized design model of clamping mechanism was established by analyzing its composition principles, maximizing its working radius as the optimization target and considering the position of each revolute pair, weight of support base, extreme positions, range of working radius, kinematic stability of pressure rod, stroke of drive rod as the constraints. In the model validation experiments, a round plastic product with clamping diameter of 40cm was choosed as the processed sample, the results of kinematic analysis of clamping mechanism show the curves of the displacement change of pressure rod, the ratio change between the pressure rod speed and driving rod speed caused by the displacement changes of drive rod. Finally, the velocity curve of driving rod was planned. Simulation experiments indicate that the results of optimization and kinematic analysis meet the design requirements, and this paper provides an important reference value to the optimized design and automatic control of trimming robot.

    Experiments on Hot Stamping of Car Carling of High Strength Steel
    Wang Min, Zhang Chun, Zhang Yu, Li Shaobing, Wang Qiongshuang
    2016, 27(03):  391-397. 
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    Experiments on hot stamping of car carlings were performed on independently developed test line, and the effects of uncoated and Al-Si coated sheets of 22MnB5 under various lubrications on forming quality, microstructures and properties of complex parts were revealed and compared. The results obtained show that: ①compared with the uncoated sheet (US), the depths of oxidation and decarburization are reduced by using the coated sheet (CS), but pores and cracks are formed in the coating during forming, which results in fractures in parts. The fractures can not be eliminated under water-based graphite lubrication,and application of glass lubrication can avoid fractures. ②The US is higher in tensile and yield strengths than the CS under no lubrication and water-based graphite lubrication, and the CS under glass lubrication is lowest. The US has a higher elongation than the CS. ③The CS under glass lubrication is lower in surface roughness than the UC, and the CS under no lubrication and water-based graphite lubrication are the highest.

    Analyses  of  Initial  Deformation  Conditions  for  Light  Hydroforming Axle Housing  and Forming Experiments
    Wang Liandong, Xu Yongsheng, Chen Xujing, Wu Na,
    2016, 27(03):  398-402. 
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    The  hydroforming technology of light axle housing was introduced.The formula of initial internal pressure was  deduced,and the influences of the relation of the internal pressure and axial thrust (axial stress ratio)in the pre-bulging process  on  the deformation sequence was predicted. The hydroforming experiments were done on general hydraulic machine under two different  load  paths.Under the first load path,the initial axial stress  ratio  was negative and the pressure  was constant throughout  the  feeding process,the pre-bulging tube was first deformed to a double-drum type with the diameter of two sides larger than the central, and the central part was finally bulged by increasing the internal pressure. Under the second load path,the initial axial stress ratio was positive and the pressure  was  constant throughout the feeding process, the central of the tube cracked axially. The common concave defects  of the samples of two load paths were observed at the transition region between flat cone and bulging area, and it will not disappear after the final bulging.Both of the theoretical analyses  and experiments  demonstrate that the initial deformation conditions have an important influence on the pre-bulging process of light axle housing.

    Comparison of Fracture Behaviors of X80 Pipeline Steel Welded Joints under TEM Observation
    Xu Ning, Wang Fenghui, Luo Jinheng, Lu Yongjun
    2016, 27(03):  403-407. 
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    Three specimens of X80 pipeline steel welded joint regions were in situ TEM tensile test by observing initiation and propagation of cracks in each region, the micro mechanical behaviors were studied and analyzed. The results show that, in the base metal zone, the crack initiation and extension are mainly composed of multiple crack, in the mode of intergranular extension, finally cause shear brittle fracture under the action of shear stress. In the heat affected zone, the main crack extension is in the direction of 45°, the whole expansion process including the main crack blunting, dislocation emission, formation of dislocation free zone in front of the main crack, microcrack nucleation, connection of main crack with microcracks, the multiscale process constantly occurrence, finally leads to quasi cleavage transgranular fracture. In the weld zone, cracks branch off from the main crack which extend to the direction of 45°, in the mixed fracture mode of intergranular and crystalline, finally lead to the transgranular brittle cleavage fracture.

    Study on Reliability Growth of Turbine of Turbocharger for Vehicle Applications with Over-speed Failure Mode
    Wang Zheng, Wang Zengquan, He Hong, Guo Kai, Wang Jinwei, Zhao Liming
    2016, 27(03):  408-412. 
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    For the over-speed reliability problem of turbine of turbocharger for vehicle applications, the stress and critical position of turbine with over-speed failure mode were analyzed. With the reliability model of turbine with over-speed failure mode, the reliability of original turbine was evaluated. Then, through the structural optimization design, the method for reliability growth of turbine with over-speed failure mode was studied. According to the parameters of stress and strength of improved turbine, the reliability of improved turbine with over-speed failure mode was studied, and the reliability growth effectiveness of turbine was analyzed. Finally, the reliability was verified qualitatively by the structural endurance test of turbocharger in a test bench. The results show that the reliability of improved turbine with over-speed failure mode increases obviously and it can meet the operation requirements of turbocharger.

    Establishment of Extended Range Electric Tractor and Its Rotary Cultivator's Simulative Platforms
    Liu Mengnan, Xu Liyou, Zhou Zhili, Liu Weiguo
    2016, 27(03):  413-419. 
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    Aimed at the existing conditions that simulation methods of in the field of electric tractor research were non-universal, and the simulation platforms concerned with working units were without complete functions. YTO-500 tractor was selected as the research object, the structural project and the driving parameters of the electric tractor were designed, the simulative platform of extended range electric tractor was established based on CRUISE. By simulating tractive behaviors of the electric and the traditional tractor, and analyzing the surficial behavior and consumption of diesel as the tractor was on a cyclic slow working conditions, the resulting curves express that this platform can simulate tractor's running conditions well. By researching the coupling relationship of torques among its power train, driving train and PTO(power take off), an equivalent model was taken out. Simulation platform of extended range electric tractor's rotary cultivator was established. The simulation expresses that the speed of the working unit approximately maintains 3.65km/h, the rotate speed of the rotary cultivator's principal axis maintains 200r/min, the simulation results correspond to the YTO 500 tractor's experiments. By comparison, the speed increases by 14%, and the consumption of fuel decreases by 34.4%.

    Adaptive Energy Control Strategy of HEV Based on Driving Cycle Recognition by LVQ Algorithm
    Deng Tao, Lu Renzhi, Li Yanan, Lin Chunsong
    2016, 27(03):  420-425. 
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    In order to reduce fuel consumption, six kinds of typical driving cycles were chosen to represent the “urban”, “suburban” and “highway”. And for vehicle fuel economy, based on fuzzy control strategy with rules,an improved PSO algorithm was adopted to optimize the engine working with motor curve factor and the engine shutting off curve factor, then the optimized parameters of membership function could be achieved under the above typical driving cycles. Furthermore, LVQ algorithm was adopted to recognize real-time driving cycle, the corresponding fuzzy control strategy could be chosen according to the recognition results, which maintained the adaptability for those driving cycles, and improved HEV's fuel economy. Simulation results show that fuel economy adopted with this control strategy is improved by 3.4% comparing to the traditional methods without cycle recognition.
    hybrid electric vehicle(HEV); driving cycle recognition; fuel economy;