Table of Content

25 March 2019, Volume 41 Issue 3 Previous Issue    Next Issue

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Global Optimization Algorithm for Planetary Hybrid Powertrain Based on Constrained Termination State Zeng Xiaohua, Wang Yue, Yang Nannan, Song Dafeng & Li Guanghan 2019, 41 (3):  239-244.  doi: 10.19562/j.chinasae.qcgc.2019.03.001 Abstract ( 200 )   PDF (943KB) ( 346 )   Save Aiming at the problem of global optimization algorithm, i.e. the huge amount of calculation and the uncertainty of penalty function in optimization objective, a hierarchical optimization framework is proposed, in which the optimization on bottom layer control is realized by using instantaneous optimal control strategy while the optimization on top layer is achieved by global optimization strategy. Meanwhile, the boundary solving method based on constrained termination state is adopted, effectively avoiding enormous debugging work for achieving the electricity balance of battery and raising calculation efficiency. The simulation results show that the optimization algorithm enhances the overall efficiency of system and further reduces the fuel consumption of vehicle References | Related Articles | Metrics

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Prediction of Preceding Car Motion Under Car-following Scenario in the Internet of Vehicle Based on Bayesian Network Zhang Jinhui, Li Keqiang, Luo Yugong, Zhang Shuwei & Li Hong 2019, 41 (3):  245-251.  doi: 10.19562/j.chinasae.qcgc.2019.03.002 Abstract ( 294 )   PDF (1667KB) ( 384 )   Save In the process of vehicle driving, the prediction of motion state of vehicle in front is an important research part of intelligent vehicle control system. Influenced by factors such as the driver's driving style, road condition, traffic flow, the speed and acceleration of the vehicle ahead, the motion state of the vehicle in a certain period of time in the future has great uncertainties, which brings difficulties to the prediction of the motion state of the vehicle ahead. This paper studies the prediction of the motion state of the vehicle ahead under the car-following conditions. In this paper, the motion characteristics of the vehicle under car-following conditions are analyzed, and Bayesian network is used to predict the speed of the vehicle ahead. The obtained motion state data of the vehicle under car-following conditions are divided into training set and test set. The training set is used to identify the parameters of the front vehicle speed for prediction of Bayesian network parameters, and the test set is used to verify the prediction effect of Bayesian network for front vehicle speed prediction. The prediction results show that the actual speed of the front vehicle is within 95% confidence interval predicted by Bayesian network for the prediction of the front vehicle speed in the next 0.1,0.5,1 and 2s References | Related Articles | Metrics

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A Research on Security of Information Propagation of CACC Vehicles Under Internet of Vehicles Environment Wei Lei, Wang Yunpeng, Qin Hongmao & Yu Guizhen 2019, 41 (3):  252-258.  doi: 10.19562/j.chinasae.qcgc.2019.03.003 Abstract ( 322 )   PDF (2401KB) ( 381 )   Save To analyze the virus propagation under the road environment mixed with CACC vehicles and common vehicles, considering the interaction among traffic flow, information flow and virus propagation, CACC vehicle virus infection probability is calculated and the dynamic model of virus propagation is built. Then, the probability of virus infection under different environments is analyzed and the process of virus propagation is simulated. The simulation results show that reducing the probability of virus infection can control the spread of virus effectively and improve the security of information propagation of CACC vehicles,both in different communication range limits and in different traffic density environments References | Related Articles | Metrics

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Identification Method for Feature Points of Drivability Evaluation Indicators in Starting Condition Huang Wei, Liu Haijiang & Li Min 2019, 41 (3):  259-265.  doi: 10.19562/j.chinasae.qcgc.2019.03.004 Abstract ( 313 )   PDF (808KB) ( 395 )   Save Aiming at the problem that the feature points of drivability evaluation indicators in vehicle start process are inaccurately identified due to the strong specificity of engine speed waveform and external interference, a set of methods from signal preprocessing to feature point identification are proposed in this paper. The feature points are determined according to drivability evaluation indicators and the time domain features of rotational speed curve. Morphological filtering combined with empirical modal decomposition is adopted to conduct filtering processing on rotational speed signals, while the combination of D-S evidence theory and syntactic pattern is applied to feature point identification. The results of experiment show that the method proposed can effectively identify the feature points of evaluation indicators on engine speed curve in starting condition, providing an objective basis for obtaining drivability evaluation indicators later on References | Related Articles | Metrics

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Analysis of Theoretical Fuel Consumption of Hybrid Electric System Based on Energy Calculation Model Zeng Xiaohua, Li Guanghan, Song Dafeng, Zhu Guanghai & Wang Yinshu 2019, 41 (3):  266-274.  doi: 10.19562/j.chinasae.qcgc.2019.03.005 Abstract ( 261 )   PDF (997KB) ( 706 )   Save Based on the hybrid power system internal energy flow , the concept of average integrated transmission efficiency is proposed and the theoretical fuel consumption model is built on the basis of energy calculation in this paper. Combined with the basic fuel-saving approach of hybrid power system, the incremental theoretical calculation model of fuel consumption is established, considering the factors of regenerative braking, average engine fuel consumption and average integrated transmission efficiency change. Finally, the quantitative analysis of fuel consumption and the influencing factors of a typical power-split hybrid power system is carried out. Simulation results of vehicle fuel economy and the theoretical analysis of the fuel consumption influencing factors show the rationality of the proposed method References | Related Articles | Metrics

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Energy Management Strategy for PHEV Based on Predictive Control Liu Jichao & Chen Yangzhou 2019, 41 (3):  275-282.  doi: 10.19562/j.chinasae.qcgc.2019.03.006 Abstract ( 213 )   PDF (2093KB) ( 359 )   Save An online energy management strategy for PHEV based on predictive control is proposed. It utilizes BPNN to construct a trip prediction model, and uses genetic / particle swarm hybrid optimization algorithm to improve the vehicle-speed prediction accuracy of the trip prediction model. On this basis, a dynamic programming-based predictive control strategy is designed to ensure the adaptability of the trip prediction model to trip conditions and the real-time performance of the strategy. Finally, a verification simulation is conducted on the strategy proposed based on trip condition data. The results show that the trip prediction model designed can effectively predict vehicle-speeds with an accuracy higher than 93%, and the fuel consumption, emissions and real-time performance with the proposed strategy are improved compared with the existing real-time strategies and global optimization strategies References | Related Articles | Metrics

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A Research on Drag Reduction of a Van-type Truck with a Bionic Cab-roof Fairing Xu Jianmin 2019, 41 (3):  283-288.  doi: 10.19562/j.chinasae.qcgc.2019.03.007 Abstract ( 238 )   PDF (3895KB) ( 437 )   Save In order to reduce the aerodynamic resistance of a van-type truck, six cab-roof fairings are designed and added on the truck model to conduct a numerical simulation on their aerodynamic characteristics, with the distributions of velocity, pressure and turbulent kinetic energy in the exterior flow field of truck model obtained, and the drag reduction mechanism of different fairings are analyzed in detail. On this basis, a bionic cab-roof fairing is designed by mimicking the head shape of a seal, and its drag reduction performance on truck is simulated. The results show that all six cab-roof fairings previously designed have a certain effects of drag reduction, but the bionic cab-roof fairing designed later can greatly improve the flow field structure at cab-roof and has better drag reduction effect, with a drag coefficient 31.1% lower than that of original truck model References | Related Articles | Metrics

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Injury Responses of the Dummy Based on Chinese Anthropometric Data in Frontal Crash Yan Lingbo, Xie Wenna, Xu Wei, Cao Libo, Dai Hongliang & Zhang Kai 2019, 41 (3):  289-297.  doi: 10.19562/j.chinasae.qcgc.2019.03.008 Abstract ( 286 )   PDF (1973KB) ( 663 )   Save In order to investigate the injury responses of Chinese occupants in vehicle frontal crash, the FE model for Chinese 50th-percentile male dummy conforming to Chinese anthropometric features is developed by scaling all body segments based on Chinese anthropometric data and the current FE model for Hybrid III 50th-percentile dummy. The model for the driver restraint system of a production car is established and validated with LS-DYNA, the injury responses of Chinese 50th-percentile male dummy and Hybrid III 50th-percentile dummy under the same frontal crash condition are contrastively analyzed, and the effects of the ignition time, vent diameter and gas mass flow rate of airbag on the injury responses of these two dummies are studied. The results show that compared with Hybrid III 50th-percentile dummy, the Chinese 50th-percentile male dummy has higher risk of head injury and may have a lower risk of thorax injury. The optimum airbag parameters for Hybrid III 50th-percentile dummy can’t necessarily provide best protection for Chinese 50th-percentile male dummy and the influence tendencies of some airbag parameters for these two dummies may even be just the opposite References | Related Articles | Metrics

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Hierarchic Braking Strategy for Active Collision Avoidance and Its Verification Based on Drivers Characteristics Hu Yuanzhi, Yang Xicun, Liu Xi & Huang Ling 2019, 41 (3):  298-306.  doi: 10.19562/j.chinasae.qcgc.2019.03.009 Abstract ( 268 )   PDF (1948KB) ( 583 )   Save To judge the danger degree of current situation accurately and intuitively, fully utilizing the known information of inter-vehicle movement and based on safe time headway model, a new modeling method of time-to-crash (TTC) is proposed. An active collision avoidance system conforming to the collision avoidance characteristics of driver is developed based on the risk judging indicator TTC. A hierarchic braking strategy for collision avoidance is designed, whose key parameters are determined based on driver’s characteristics and real vehicle test results. In addition, a warning threshold Tw is introduced and an active collision avoidance warning strategy in audible and visual forms is designed to help driver fulfill effective collision avoidance. The results of real vehicle test show that the hierarchic braking and warning strategy of the system conform to driver’s characteristics, embody the priority and coordination of driver’s control, and can effectively avoid crash, meeting the requirements of active collision avoidance of vehicles References | Related Articles | Metrics

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A Study on Vehicle Collision Risk Estimation Algorithm Based on External Dynamic Environment Zhou Bing, Zhao Hua, Wu Xiaojian, Chen Xiaolong & Zeng Fanyi 2019, 41 (3):  307-312.  doi: 10.19562/j.chinasae.qcgc.2019.03.010 Abstract ( 235 )   PDF (1193KB) ( 333 )   Save In view of that the most existing vehicle collision risk estimation algorithms under emergency only consider the uncertainty caused by measurement noise interference, a vehicle collision risk estimation algorithm is proposed concurrently considering both the uncertainty in dynamic road environment and that caused by measurement noise interference. Firstly, the fuzzy inference model for “road condition-speed-maximum acceleration” is constructed, in which the maximum braking acceleration of vehicle is quickly obtained by using the intelligent algorithm of fuzzy inference based on road condition and host vehicle speed. A kinematics-based prediction model is also established, and with consideration of the dynamic changes of road adhesion condition and the uncertainty caused by measurement noise interference, Monte Carlo method is used to calculate the crash probability of host vehicle under current driving environment. The trajectories of vehicle emergency braking and steering are predicted according to vehicle dynamics and road-related parameters and hence the crash probabilities with collision avoidance by braking or lane change are obtained. Taking the intersection crossing and rear end collision conditions as examples, the crash probabilities with braking and steering collision avoidances under different road conditions are contrastively analyzed so as to choose a reasonable mode of vehicle collision avoidance. The results show that the proposed risk estimation algorithm is relatively consistent with the emergency collision avoidance maneuver in real dynamic traffic environment with good effectiveness and feasibility References | Related Articles | Metrics

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The Suppression of Torque Fluctuation in Mode Switching of EPS Based on Flux-weakening Control Zhao Linfeng, Zhang Ruichen, Xie Youhao, Zhang Rongyun & Shen Xue 2019, 41 (3):  313-319.  doi: 10.19562/j.chinasae.qcgc.2019.03.011 Abstract ( 182 )   PDF (1823KB) ( 448 )   Save In view of the effects of the torque fluctuation on the performance of electric power steering system in the process of switching between id=0 control and flux-weakening control in permanent magnet synchronous motor, a load torque observer is designed to compensate the output torque of flux-weakening control in speed loop, and a torque smooth switching module is added during mode switching, so the problem of manipulation torque fluctuation caused by the abrupt change of torque in mode switching process is solved. The results of both simulation and test show that through the load feed-forward compensation by load torque observer, the robustness of system to load disturbances is enhanced, and the torque smooth switching module added well suppress the fluctuation of manipulation torque in mode switching process, so the hand feeling of driver on the heavy turning of steering wheel and torque fluctuation is improved References | Related Articles | Metrics

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A Study on Hierarchical Control of Directional Stability of Electric-wheel Vehicle with Electro-hydraulic Braking Ma Jinlin, Wang Xinfei, Zhang Houzhong, Jiang Haobin & Xu Xing 2019, 41 (3):  320-326.  doi: 10.19562/j.chinasae.qcgc.2019.03.012 Abstract ( 218 )   PDF (1558KB) ( 415 )   Save For the problems of sideslipping, drift and spinning in emergency braking of distributed drive electric vehicles in complicated working conditions, a hierarchical control strategy enhancing the braking stability of EVs with electro-hydraulic composite braking is proposed. The decision-making level of this strategy includes the calculation of total braking torque and corrected yawing moment; the allocation layer contains the algorithm of optimal allocation of braking torque and allocation of corrected yawing moment; the coordination layer coordinates the distribution results ensuring the stability. With the vehicle dynamics simulation platform of Simulink & Carsim, braking in μ-lowturn test and μ-split road are simulated and tested respectively. The results show that the proposed hierarchical control strategy can not only guarantee the braking effectiveness,but also improve the stability of the braking of vehicle References | Related Articles | Metrics

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Simulation on Control Strategy for Torque Distribution of Compound Brake System in a Distributed Drive Electric Vehicle Du Ronghua, Mi Siyu, Hu Lin & Meng Can 2019, 41 (3):  327-333.  doi: 10.19562/j.chinasae.qcgc.2019.03.013 Abstract ( 282 )   PDF (1003KB) ( 403 )   Save Aiming at a distributed drive electric vehicle, a control strategy for compound brake system is proposed in this paper. A hierarchical braking torque allocation control structure is adopted, in which the upper controller uses the sliding mode control strategy to solve out the target longitudinal force and yaw moment for meeting the requirements of braking efficacy and stability. The lower controller allocates the hydraulic braking torque of four wheels and the motor braking torque with weighted least square control, maximizes energy recovery by increasing the weight of motor braking force allocation and solves the objective function by using effective set algorithm. On this basis, a seven-DOF vehicle dynamics model is established with Simulink, and a simulation is carried out under the condition of butted-joint road. The results show that the control strategy proposed can meet the requirements, maximizing the recovery of braking energy while ensuring the braking stability of vehicle References | Related Articles | Metrics

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Modeling of Lithium Battery Characteristics Considering the Influence of Temperature and Hysteresis Effect Song Kai, Chen Xu & Cheng Aiguo 2019, 41 (3):  334-339.  doi: 10.19562/j.chinasae.qcgc.2019.03.014 Abstract ( 355 )   PDF (1002KB) ( 636 )   Save In order to improve the accuracy of lithium battery model, the SOC estimation error caused by hysteresis voltage is analyzed, indicating that the influence of hysteresis cannot be neglected in modeling lithium battery. Thus an equivalent hysteresis model for lithium battery is proposed based on the analysis on the changing pattern of hysteresis voltage at different temperatures and the internal electrochemical processes, affecting the dynamic characteristics of lithium battery. Then the OCV and impedance parameters are discriminated respectively by using the small constant rate charge-discharge experiment at different temperatures and the urban road driving cycle. Finally, the estimated terminal voltage and SOC of battery model are compared with experimental data. The results show that the accuracy of model can be doubled when the hysteresis effect is taken into account in lithium battery modeling References | Related Articles | Metrics

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The Analysis of Single-point Preview Driver Model Based on Time Coefficient Ma Fangwu, She Shuo, Wu Liang, Wang Jiawei, Shi Jinzhu & Dai Kai 2019, 41 (3):  340-345.  doi: 10.19562/j.chinasae.qcgc.2019.03.015 Abstract ( 239 )   PDF (889KB) ( 502 )   Save A novel single-point preview driver model is established in this paper, and the effects of preview time and error feedback coefficient on tracking performance are analyzed. An assumption is put forward that the radical cause of the steady-state error is “there is a coupling between longitudinal preview time and lateral acceleration time”. By setting a time coefficient F, characterizing the relationship between lateral acceleration time and longitudinal preview time, this model can track a given curved road without error, while ensuring the vibration frequency of the system adjustable References | Related Articles | Metrics

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A Study on AHSS Die Life Based on Dynamic Friction and Wear Coefficients Nie Xin & Wang Chenglong 2019, 41 (3):  346-353.  doi: 10.19562/j.chinasae.qcgc.2019.03.016 Abstract ( 337 )   PDF (1373KB) ( 444 )   Save In order to more accurately calculate the wear of advanced high-strength steel (AHSS) stamping die, predict die life, and reveal the effects of constantly changing nodes' pressure and relative sliding velocity during stamping on friction coefficient and wear coefficient, orthogonal experiments on friction and wear are carried out under different pressures and velocities, with corresponding friction coefficient and wear coefficient obtained. Then curve fitting is conducted with pressure and velocity as independent variables and friction coefficient and wear coefficient as dependent variables and a calculation model for dynamic friction coefficient and wear coefficient is put forward. Due to the hardness of plating layer on die surface is changed with its thickness,the coupled die face wear equations for the changing hardness and wear coefficient of die face are established based on experiments and theoretical derivation, a numerical simulation on stamping process is performed by using the model for dynamically changing friction coefficient in stead of Coulomb friction model, and die wear is calculated using coupled die face wear equations, whose results are compared with the scanning data of worn die face. The results show that compared with traditional calculation using constant friction and wear coefficients, the accuracy of wear results calculated by the method proposed is 15.05% higher, and the life prediction on an AHSS drawing die using this method indicates that after 59,000 parts are stamped, the plating layer on some areas of die face is seriously worn and need repair References | Related Articles | Metrics

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A Study on Parametric Optimization of PP Core Sandwich Structure and Its Application to Car Body Based on Utility Function Theory Cui An, Chen Chong, Zhang Shiguang, Yu Duonian, Zhang Han, Sun Wenlong & Hao Yuxing 2019, 41 (3):  354-359.  doi: 10.19562/j.chinasae.qcgc.2019.03.017 Abstract ( 217 )   PDF (1058KB) ( 353 )   Save For achieving better performance of polypropylene (PP)-core sandwich structure being substituted for steel panel, a few design attributes, e.g. stiffness, strength, mass and cost etc. of body panels are chosen to build an optimization model for sandwich structure parameter (thickness) based on multi-attribute utility function theory. Then the multi-objective optimization problem of sandwich structure is transformed into a single objective optimization problem, a parametric optimization program is developed with MATLAB,and an optimization is conducted and verified by experiment. Finally, the optimized sandwich structure is applied to the fire wall of a car and a finite element simulation is performed to analyze and evaluate the car body structural performances before and after fire wall substitution. It is shown that the structural performance of the car body with optimized sandwich fire wall is apparently improved References | Related Articles | Metrics