Table of Content

25 February 2019, Volume 41 Issue 2 Previous Issue    Next Issue

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A Research on Engine Electric Control for Electric-drive Mobile Platform Su Jianqiang, Wang Zhihe 2019, 41 (2):  121-125.  doi: 10.19562/j.chinasae.qcgc.2019.02.001 Abstract ( 259 )   PDF (969KB) ( 409 )   Save The stepper motor control system is designed with DSP 2808 of TI company as its core for fulfilling the electric control of engine fuel pump rack in electric-drive mobile platform. The system achieves the engine fuel rack control by controlling the driving-pulse number of stepper motor, and a fuzzy PI control for engine speed is proposed to tackle the problem of engine speed instability caused by stepper motor fluctuation and engine nonlinearity during engine speed closed-loop control. Experimental results show that the pulses of stepper motor respond swiftly, engine speed has a good dynamic response and the output voltage of generator is stable. These provide reliable electric energy for mobile platform, meeting its requirements on engine control References | Related Articles | Metrics

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An Experimental Study on MF-gasoline Blends Direct Injection Spray Characteristics Gao Dongzhi, Guo Yong, Wang Fengbin, Fu Tieqiang 2019, 41 (2):  126-132.  doi: 10.19562/j.chinasae.qcgc.2019.02.002 Abstract ( 200 )   PDF (1751KB) ( 395 )   Save Direct injection (DI) system has been commonly used in spark ignition engines for its good performance in fuel economy, combustion efficiency, emissions and cold-start. Currently,2-methylfuran (MF) has already been a more attractive biomass fuel because of its better performance than ethanol. However, there is little study on the DI spray characteristics of 2-MF-gasoline blends. In this paper, the spray characteristics of 2-methylfuran-gasoline blends M20 (20% volume fraction MF-gasoline blend fuel), M40 and pure gasoline from 6-hole DI injector are investigated under various ambient pressure and fuel temperature using high-speed schlieren photography. The spray parameters include spray penetration, spray cone angle and spray area. The results show that there are two different spray forms, flash boiling and non-flash boiling. When flash boiling occurs, the spray penetration increases with the increase of MF ratio. With the reduction of ambient pressure, the spray penetration decreases firstly and then increases. And the spray cone angle is greater than that without flash boiling. The spray area increases with the increase of MF ratio and the spray area is negatively correlated with the fuel temperature. When there is no flash boiling, with the increase of MF ratio, the spray penetration decreases References | Related Articles | Metrics

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A Model-based Research on Exhaust Temperature Control for DPF Active Regeneration Huang Tiexiong, Hu Guangdi, Guo Feng, Yang Mingliang 2019, 41 (2):  133-139.  doi: 10.19562/j.chinasae.qcgc.2019.02.003 Abstract ( 245 )   PDF (990KB) ( 611 )   Save Initiation of active regeneration of diesel particulate filter(DPF) requires that the diesel engine exhaust gas temperature be raised to 500℃ or above and maintained at the operating temperature for a moderately long period of time. To reduce the uncertainties by time-delays and strong disturbances of the control object and risks of active regeneration caused by high exhaust temperature, an optimized regeneration temperature control algorithm and controller structure are proposed based on model-based control strategy development, and simulation analysis and parameter optimization are carried out. Considering practical application requirements, the designed control structure adopts the scheme of gain compensation, feedforward solution and feedback control based on engine exhaust temperature and exhaust flow, which takes account of both cost and performance and has strong adaptability and operability. The results of simulation, bench test and vehicle road test show that the overshoot of actual exhaust temperature control in active regeneration process is less than 3% and the steady-state control error remains less than 25℃ even under aggressive disturbances during transient vehicle operation References | Related Articles | Metrics

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Analysis and Experimental Study on the Influence of Bus-bar on the Temperature and Current Equalization of Battery Module Fan Guanghui, Yu Jianwu, Luo Hong, Lu Yuetuo, Tong Ruiqing 2019, 41 (2):  140-146.  doi: 10.19562/j.chinasae.qcgc.2019.02.004 Abstract ( 235 )   PDF (2747KB) ( 455 )   Save A thermo-electric coupling numerical calculation on the heat generation characteristics of the battery module in an electric vehicle is conducted to study the effects of discharge rate, current I/O mode, bus-bar contact area and current I/O position on the current density and the temperature field of battery module. The results show that the discharge rate significantly affects the temperature rise and the heat exchange between bus-bar and cell, thus the analysis on battery heat generation in high current rate charge / discharge conditions should take the electro-thermal effects of bus-bar into consideration. An experimental study on the temperature rise in battery module under different discharge rates is carried out by using battery charge / discharge testing system and under an ambient temperature of 28.5℃, the highest temperature rise measured is basically consistent with the result of thermo-electric coupling numerical calculation, demonstrating that numerical simulation can well predict the temperature rise characteristics of bus-bar References | Related Articles | Metrics

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Aerodynamic Performance Optimization and Verification of a SUV Peng Lijuan, Yuan Xiayi, Chen Zhifu, Tang Zhuliang, Chen Lin, Wang Chaoyi 2019, 41 (2):  147-152.  doi: 10.19562/j.chinasae.qcgc.2019.02.005 Abstract ( 274 )   PDF (2006KB) ( 481 )   Save Based on the model for the model-change version of a SUV and by using mesh morphing technology and CFD software, the effects of exterior styling surfaces on aerodynamic drag are analyzed. On this basis, the key exterior styling surfaces and aerodynamic accessories having greater influences on aerodynamic drag are optimized successively. As a result, the aerodynamic drag coefficient of the model lowers from original 0.407 down to 0.347 and its measured value is 0.34 by wind tunnel test, with a simulation error of only 2.06% References | Related Articles | Metrics

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Simulation Study on Driving Risk Discrimination Based on Driver's Collision Avoidance Behavior Xiong Xiaoxia, Chen Long, Liang Jun, Cai Yingfeng, Jiang Haobin 2019, 41 (2):  153-160.  doi: 10.19562/j.chinasae.qcgc.2019.02.006 Abstract ( 422 )   PDF (885KB) ( 523 )   Save A driving risk classification method based on driver's collision avoidance behavior is proposed, and the driving risk discrimination algorithms under different driving modes are established by using support vector machine with concurrent consideration of the effects of driving behavior, road condition and environmental factor on driving risk states. Training and validation on prediction algorithm are conducted based on the “100-car” natural driving data from Virginia Tech in the US. The results show that in driving risk prediction modeling, the consideration of the discrepancies in driver's behavior, road condition and environmental factor, in particular the driver's distraction state, is conducive to increasing the accuracy of prediction model. In addition, under the condition of false positive rate lower than 5%, the prediction of high-risk state for future driving process by using prediction algorithm created has higher accuracy, in favor of giving timely warning or correction aids to drivers in near danger state, providing a new idea for the research on collision avoidance warning strategy and control method References | Related Articles | Metrics

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Thermal Reliability Analysis of In-wheel Wet Brake Assembly Under High-intensity Braking with Multi-field Coupling Sun Dongye, Liu Sheng, Hao Yunzhi, Luo Yong, Wang Yong, Qin Datong 2019, 41 (2):  161-169.  doi: 10.19562/j.chinasae.qcgc.2019.02.007 Abstract ( 325 )   PDF (1193KB) ( 380 )   Save In view of the degradation of reliability, braking performance and fuel economy of vehicle,caused by the heat accumulation in the in-wheel wet brake assembly during high-intensity braking, the finite element models for the assembly and its brake are built to analyze the thermal reliability of wet brake under the coupling of temperature filed and stress field during emergency braking or continuous braking. After the heat source system model of the assembly is established based on bond graph theory, the overall thermal reliability of the assembly under the coupling of thermal field and flow field during long-time high frequent braking is analyzed with consideration of the convective heat transfer of air and lubricant. The results show that under the common actions of stress field, temperature field and flow field, the thermal reliability of the wet bake assembly is significantly lowered during high strength braking and the results of numerical simulation and test verify the correctness of analysis methodology and the effectiveness of outcome References | Related Articles | Metrics

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Path Planning and Tracking Control for Collision Avoidance of a 4WIS-4WID Electric Vehicle Hang Peng, Chen Xinbo, Zhang Bang, Shi Pengfei, Tang Tingju 2019, 41 (2):  170-176.  doi: 10.19562/j.chinasae.qcgc.2019.02.008 Abstract ( 490 )   PDF (1038KB) ( 655 )   Save Four-wheel independent steering and four-wheel independent drive electric vehicle (4WIS-4WID EV) has good maneuverability at low speed and superior stability at high speed, so is an ideal autonomous vehicle. An active collision avoidance system for 4WIS-4WID EV is designed in this paper, mainly consisting of path planning and tracking control. Firstly, the path planning algorithm for collision avoidance is proposed using seven-order polynomial based on vehicle kinematic model. Then, the model predictive controller for path tracking is designed based on the simplified 2 DOF dynamic model. Four-wheel steering and direct yaw-moment control are applied to the path tracking algorithm to improve the handling stability of vehicle. The active collision avoidance performance and robustness of the system are verified by simulations under the conditions of different road adhesive coefficients and crosswind disturbance References | Related Articles | Metrics

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A Study on Hydraulic Torque Converter Sectional Slip Control for CVT Vehicle Start Lei Yulong, Hu Jianlong, Fu Yao, Jia Yuzhe, Wang Linbo, Cheng Jing 2019, 41 (2):  177-183.  doi: 10.19562/j.chinasae.qcgc.2019.02.009 Abstract ( 240 )   PDF (889KB) ( 432 )   Save To solve the problems of slow acceleration response, high engine speed and engine speed fluctuations in the starting process of CVT vehicle torque converter, a segmented slip control strategy of lock-up clutch at starting conditions is brought forward based on constant engine speed control and a vehicle co-simulation platform based on Amesim and Matlab/Simulink is established to verify the proposed strategy. The simulation results show that the proposed control strategy can advance the locking time of the torque converter by about 1.2s and reduce the fuel consumption by 5.385% at the start stage of 50% throttle opening. The proposed strategy provides a new method for further tapping the fuel-efficient potential of the powertrain References | Related Articles | Metrics

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Analysis and Control on Vibration Resulted from Engine Start of Hybrid Electric Vehicle Wang Bo, Zhang Zhendong, Yu Haisheng, Cheng Huijun, Wang Chen 2019, 41 (2):  184-190.  doi: 10.19562/j.chinasae.qcgc.2019.02.010 Abstract ( 345 )   PDF (1069KB) ( 470 )   Save To solve the problem of body wobbling of a hybrid electric vehicle with a new power splitting mechanism at the moment of engine ignition, experimental research and data analysis are carried out. The vibration model of transmission system is established, and the excitation source and transmission path of the system are analyzed. Without changing the type of suspension and the inherent characteristics of power transmission system, the method of reducing the excitation source is adopted to optimize the engine output torque. Based on analysis of the factors affecting the engine output torque, the calculation formula of the engine output torque is deduced and the target optimal torque curve is given. Then the optimal control parameters of the engine torque at the moment of ignition are obtained by using particle swarm optimization algorithm. Finally, the effectiveness of the method is verified on the real vehicle References | Related Articles | Metrics

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A Study on the Application of Passive Vibration Absorber Group on Powertrain System Wideband Vibration Reduction Gao Pu, Xiang Changle, Liu Hui, Zhou Han 2019, 41 (2):  191-197.  doi: 10.19562/j.chinasae.qcgc.2019.02.011 Abstract ( 217 )   PDF (931KB) ( 441 )   Save Based on the 4-DOF dynamic model of the vehicle powertrain system, the key moment of inertia affecting the natural vibration of each order is obtained by eigenvalue sensitivity analysis, and the installation position of each dynamic vibration absorber required for excitation near the resonance frequency band is determined. According to the relationship between the wideband torque model of the external excitation and the natural vibration of the system, the vibration frequency band is segmented and the corresponding dynamic vibration absorber is installed in the corresponding position of each frequency band for segmentation control. Then, the optimal parameter matching design is carried out for each dynamic vibration absorber, and the frequency shift characteristic and the natural vibration energy of the powertrain system with the dynamic vibration absorber group are analyzed to prove the vibration reduction mechanism. Finally, the transient vibration analysis of the powertrain system with the dynamic vibration absorber is carried out to verify the effectiveness of the scheme for the wideband vibration reduction References | Related Articles | Metrics

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Vehicle State Estimation Based on the Combination of Unscented Kalman Filtering and Genetic Algorithm Zhou Weiqi, Qi Xiang, Chen Long, Xu Xing 2019, 41 (2):  198-205.  doi: 10.19562/j.chinasae.qcgc.2019.02.012 Abstract ( 320 )   PDF (1129KB) ( 450 )   Save In view of the uncertain situation of the statistical characteristics of process noise and measurement noise in vehicle state estimation, a new adaptive filtering algorithm is put forward by combining UKF algorithm with genetic one for reducing the disturbance of noise to the results of estimation. In order to achieve higher accuracy, a 7 DOF nonlinear vehicle dynamics model is established and by combining ‘magic formula’ tire model, the longitudinal and lateral velocities, tire force and the sideslip angle of mass center are estimated respectively. While UKF algorithm is applied to estimate vehicle states, the genetic algorithm is introduced, and the process noise and measurement noise are optimized based on fitness function to realize the adaptation of noise with the accuracy of estimation greatly enhanced. The results of simulation and road test show that the combination of UKF and genetic algorithms can improve the accuracy of vehicle state estimation with good disturbance resistance References | Related Articles | Metrics

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A Research on Intelligent Obstacle Avoidance of Unmanned Vehicle Based on DDPG Algorithm Xu Guoyan, Zong Xiaopeng, Yu Guizhen, Su Hongjie 2019, 41 (2):  206-212.  doi: 10.19562/j.chinasae.qcgc.2019.02.013 Abstract ( 441 )   PDF (1546KB) ( 976 )   Save An intelligent obstacle avoidance scheme for unmanned vehicle based on reinforcement learning is proposed in this paper. In view of that the movement of unmanned vehicle must meet both interior and exterior constraints, including vehicle dynamics constraints and traffic rule constraints and its output must be continuous, which the traditional reinforcement learning cannot assure, an improved deep deterministic policy gradient algorithm is proposed to tackle continuous motion space issue and achieve the continuous output of steering wheel angle and acceleration. Multi-source sensor data fusion is adopted to fulfill the state input of unmanned vehicle obstacle avoidance algorithm and both interior and exterior constraints are added to make output motion more reasonable and effective. Finally a simulation is conducted on the open-source simulation platform TORCS and the effectiveness and robustness of the algorithm verified References | Related Articles | Metrics

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Identification Strategy of Driving Style Based on Random Forest Zhu Bing, Li Weinan, Wang Zhen, Zhao Jian, He Rui, Han Jiayi 2019, 41 (2):  213-218.  doi: 10.19562/j.chinasae.qcgc.2019.02.014 Abstract ( 321 )   PDF (952KB) ( 515 )   Save Understanding and identification of driver's driving style are of great significance to the human-machine harmonious interaction under different control systems such as automatic driving and assistant driving. A driving style identification strategy based on random forest model is proposed in this paper. Firstly, the driver's driving data acquisition system is set up. Based on that, the driving data of several drivers are collected in real time under typical car-following scenarios. According to hierarchical clustering theory, the driving style are “labeled”. On this basis, a random forest model is introduced to establish driving style identification strategy, and importance analysis, model training and identification test are carried out. The test results show that the driving style identification strategy based on the random forest model can effectively identify driver's driving style and the overall accuracy of the model can reach 97.1% References | Related Articles | Metrics

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Research and Application of Vehicle Welding Spot Failure Prediction Ji Yurong, Sun Xiaoyu 2019, 41 (2):  219-224.  doi: 10.19562/j.chinasae.qcgc.2019.02.015 Abstract ( 369 )   PDF (1804KB) ( 513 )   Save By adding failure criterion on welding spots in CAE model, the difficulty in accurately predicting welding spot failure during vehicle crash simulation with finite element analysis is overcome. Welding spot failure criteria are set up based on welding spot failure parameters obtained from the mechanical performance test of welding spots, and the effectiveness of welding spot failure criteria is verified by comparing the results of simulation and test on multi-welding-spot components. The results show that adding failure criterion on welding spots can truly reflect the loading and failure conditions of welding spots. Then the prediction on welding spot failure is conducted on vehicle crash model and is compared with the results of real-vehicle crash test. The outcomes indicate that the method adopted can accurately predict the welding spot failure situation in real vehicle crash, having guiding significance for the crash safety design of vehicle References | Related Articles | Metrics

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A Study on the Effects of Temperature on the Failure Strength of Steel-aluminum Adhesive Joints Na Jingxin, Pu Leixin, Qin Guofeng, Chen Lijun 2019, 41 (2):  225-231.  doi: 10.19562/j.chinasae.qcgc.2019.02.016 Abstract ( 219 )   PDF (1079KB) ( 380 )   Save In order to provide reference and guidance for the practical application of steel-aluminum adhesive structure to vehicle, three kinds of joints with different stress states are selected, i.e. thick base shear joint, 45° scarf joint and butt joint, for test under 5 different temperatures of -40,-10,25,50 and 80℃, to study the effects of temperature on the failure load, failure mode and failure criterion of plexus MA832 steel-aluminum adhesive joints. The results show that with the increase of temperature, the failure strength of three different joints all show a downward trend of cubic polynomial curve, but the descending amplitude is related to the stress state of the joints. Among them, the failure strength of thick base shear joint falls the most obviously, when temperature rises from 25 to 80℃ its failure strength drops by about 56%, but the rise of temperature does not change the failure mode of adhesive joints, which is characterized by cohesive failure. In addition, through the fitting of adhesive layer stress curve, the quadratic stress failure criterion of Plexus MA832 adhesive layer at different temperatures is established, and based on which the failure criterion expression of steel-aluminum adhesive joints at any temperature is given in the end References | Related Articles | Metrics

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Lightweight Design of CFRP Thin-walled Beam Bumper with Twelve Right-angle Section Chen Guang, Lu Shen, Zhao Zijian, Chen Chao, Lou Lei 2019, 41 (2):  232-238.  doi: 10.19562/j.chinasae.qcgc.2019.02.017 Abstract ( 251 )   PDF (1688KB) ( 390 )   Save Aiming at the light-weight modification design of the bumper assembly of a B-class car, its energy absorption target is determined based on crash energy management method and the detailed dimension design is conducted with forward design scheme. The energy-absorbing box adopts a two-layer twelve-right-angle-section thin-walled beam structure with an outer layer of carbon fiber reinforced polymer and an inner layer of low-carbon steel sheet, and its theoretical thickness values of both layers are determined based on the collapse theory for thin-walled beam. The bumper beam uses the same twelve-right-angle-section thin-walled beam structure but with single layer and its theoretical thickness value is determined by using equivalent stiffness substitution method. A series of comparison schemes are designed based on theoretical thickness values and a reasonable scheme is finally selected through high-speed and low-speed crash verifications, achieving a mass reduction rate of 41.5% for bumper assembly while meeting the requirements of energy absorption References | Related Articles | Metrics