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Administrator by China Associction for Science and Technology
Sponsored by China Society of Automotive Engineers
Published by AUTO FAN Magazine Co. Ltd.

Table of Content

    25 April 2019, Volume 41 Issue 4 Previous Issue    Next Issue
    Research and Development of a Multi-functional Fuel Cell Stack Test Platform
    Fang Chuan, Huang Haiyan, Xu Liangfei, Li Jianqiu, Hong Po, Jiang Hongliang, Zhao Xingwang , Hu Zunyan
    2019, 41 (4):  361-365.  doi: 10.19562/j.chinasae.qcgc.2019.04.001
    Abstract ( 394 )   PDF (2198KB) ( 489 )   Save
    In view of the current situation that commercial test platforms for fuel cell stack cannot meet its R&D and test requirements, e.g. its air and hydrogen supply systems cannot fulfill the functions such as active regulation on the air humidity and voltage of fuel cell stack etc., a multi-functional fuel cell stack test platform is developed based on the outcomes of years of research of the fuel cell research team in Tsinghua University. The platform can not only accurately provide the fuel cell stack with a wide range of operating conditions close to the real operating conditions on a vehicle, but also realize the output characteristics of fuel cell stack required by the research, owing to the active regulation function of anode and cathode outlet pressures and anode / cathode dual recirculation function added.
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    Innovative Design and Parametric Simulation Analysis of Multi-DOF Spherical Induction Motor
    Deng Tao, Su Zhenhua, Tang Peng , Jiang Lu
    2019, 41 (4):  366-372.  doi: 10.19562/j.chinasae.qcgc.2019.04.002
    Abstract ( 173 )   PDF (2818KB) ( 520 )   Save
    For meeting the functional requirements of the multi-DOF drive unit for omnidirectional vehicle wheels and multi-orientation camera for smart car, and remedying the defects of structural complexities, control difficulties and poor dynamic performance caused by integrating multiple conventional motors to achieve multi-DOF drive, a multi-DOF spherical induction motor is proposed based on the theory of linear induction motor. The spherical induction motor is composed of three blocks of stator with arc surface and a spherical hollow rotor, and can realize two-DOF drive. Differing from the traditional motor, which output the torque through its shaft, the spherical induction motor directly output its torque from motor's surface due to the unique structure of stator. Firstly, the dimensional parameters of the multi-DOF spherical induction motor are designed in this paper. Then its model is built with ANSYS Maxwell software and a transient electromagnetic simulation is conducted. Meanwhile, a parametric analysis is performed on the spherical induction motor to acquire its characteristic curves at different voltages and frequencies and to reveal the mechanism of torque and rotation speed control for the motor. The results show that the torque and power of the multi-DOF spherical induction motor increase with the rise of voltage, while with the increase of frequency its torque and power fall and the range of rotational speed widens. The performances of the spherical induction motor designed meets the requirements preset.
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    The Effects of Oil Cooling on the Temperature Field of Out-rotor In-wheel Motor Under Vehicle Operation Environment
    Zhao Lanping, Jiang Congxi, Xu Xin , Yang Zhigang
    2019, 41 (4):  373-380.  doi: 10.19562/j.chinasae.qcgc.2019.04.003
    Abstract ( 254 )   PDF (4662KB) ( 578 )   Save
    In view of the special structure of outer rotor in-wheel motors for electric vehicles, the temperature characteristics of the in-wheel motor are studied under vehicle operation environment, to compare the temperature fields of the different parts of the motor under natural air cooling and oil cooling modes. Then on this basis, the influences of different types of cooling oil on the highest temperature in different parts of the motor are studied. The results indicate that the simulation outcomes well agree with that of hot environment wind tunnel test of vehicle. The oil cooling can effectively reduce the maximum temperatures inside the in-wheel motor, and plays a good role in temperature equalization in the motor. All the four types of cooling oil can significantly lower the highest temperature of motor coil, the higher the thermal conductivity of cooling oil, the stronger the capability of heat transfer and temperature equalization, and hence the better the cooling effects of the motor.
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    Calculation Method of the Proportion of Heat Dissipated Through Engine Cooling System for Engine Retarder
    Yan Shengyu, Xiao Runmou, Zhao Jun , Wang Cong
    2019, 41 (4):  381-387.  doi: 10.19562/j.chinasae.qcgc.2019.04.004
    Abstract ( 214 )   PDF (769KB) ( 457 )   Save
    In order to reasonably assign the limited heat dissipated power of the engine cooling system, a thermal balance calculation model of engine retarder is built, a measuring method for the heat dissipation power of engine retarder through cooling system is proposed, and the power balances in two different states (engine driving vehicle running and vehicle coasting with engine retarder braking) are compared. The rolling resistance coefficient and aerodynamic resistance coefficient are determined by field test and hence the braking force characteristics of engine retarder is obtained. Through the road tests on G312 national road and G5 highway, the effectiveness of the heat balance calculation model is validated. The results show that the thermal balance model adopted can simply calculation procedure, and the main channel of heat dissipation of engine retarder is engine cooling system,whose power proportion of heat dissipation for engine retarder is closely related to the gear ratio of transmission, the temperature difference between the inlet and outlet of radiator, vehicle speed and braking force.
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    A Study on the Matching of Air Inlet Grille Angle and Cooling Fan Speed in a Car
    Liu Chuanbo, Zhang Ruonan, Duan Mao, Liu Kang , Wang Wei
    2019, 41 (4):  388-394.  doi: 10.19562/j.chinasae.qcgc.2019.04.005
    Abstract ( 310 )   PDF (2250KB) ( 678 )   Save
    The front-end intake air volume of vehicle cooling system directly affects the heat dissipation performance and aerodynamic resistance of engine compartment. In view of the overcool and overheat of engine under the high-speed and lower-speed conditions of the passenger car with active grille shutter (AGS), computational fluid dynamics (CFD) technique is adopted to analyze the effects of AGS angle and fan speed on the flow field of engine compartment. The optimization matching criteria and scheme of grille angle and fan speed are established and the real effects of matching scheme are verified by the simulation on a real example. The results show that the matching scheme of air intake module proposed can meet the requirements of heat dissipation under extreme conditions with a fuel consumption reduced by 0.166 L/100km.
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    A Research on Emergency Obstacle Avoidance of Intelligent Vehicle Based on Braking and Steering Coordinated Control
    Wang Qidong, Li Yinxiang, Chen Wuwei, Zhao Linfeng , Xie Youhao
    2019, 41 (4):  395-403.  doi: 10.19562/j.chinasae.qcgc.2019.04.006
    Abstract ( 301 )   PDF (1990KB) ( 590 )   Save
    In order to enable vehicles to change lane quickly and steadily to avoid obstacles in emergencies, this paper combines vehicle longitudinal with lateral control. Considering the stability problems that may be caused by restrictions of road adhesion conditions in an emergency braking steering process of obstacle avoidance. Ideal longitudinal force and lateral force allocation based on Hamilton energy function is added to the planning process of emergency obstacle avoidance, and a steady state prediction with dynamic correction driver model is built to track the desired path of the planning. Then, a three-degree-of-freedom vehicle dynamics model is built by using Matlab/Simulink and the distribution of ideal longitudinal force and lateral force is validated by hardware in-loop test based on Carsim and Labview. The simulation results show that the distribution of the calculated force distribution law can make the vehicle drive to the adjacent lane in a relatively short period of time and longitudinal distance under the condition of emergency braking and steering to avoid obstacles. Finally, a vehicle test is carried out to verify the effectiveness of the proposed method.
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    A Study on Active Collision Avoidance Control of Autonomous Vehicles Based on Model Predictive Control
    Ren Yue, Zheng Ling, Zhang Wei, Yang Wei , Xiong Zhoubing
    2019, 41 (4):  404-410.  doi: 10.19562/j.chinasae.qcgc.2019.04.007
    Abstract ( 804 )   PDF (1987KB) ( 1668 )   Save
    Aiming at the problem of steering collision avoidance for autonomous vehicle, a hierarchical control method for collision avoidance is proposed. In upper-layer controller for path planning, the artificial potential field function is introduced based on vehicle kinematic model and the relative state between vehicle and obstacle is used to describe the collision risk of vehicle. While in bottom-layer controller for path tracking, the nonlinear kinetic model of vehicle and the path tracking optimization function based on optimal steering wheel angle input are established to achieve local collision avoidance path tracking. Finally Carsim/Matlab joint simulation platform is constructed to simulate the collision avoidance path planning and tracking effects of controlled vehicle under different speeds and road conditions. The results show that the upper controller can plan local collision avoidance path real time according to obstacle information, while the bottom-layer controller can control the vehicle to smoothly and stably track reference path, hence fulfilling the active collision avoidance function of vehicle.
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    Design and Optimization of a Tandem Airbag with Double Chambers for Frontal Crash
    Ge Ruhai, Gu Yaozhi, Cai Chaoyang, Huang Kexing , Chen Yuhang
    2019, 41 (4):  411-416.  doi: 10.19562/j.chinasae.qcgc.2019.04.008
    Abstract ( 225 )   PDF (1663KB) ( 427 )   Save
    Aiming at the problem that traditional airbag is prone to puncture by the impact of occupants large in stature, a novel tandem airbag with double chambers is designed to enhance its protection effects for passengers large in stature. Firstly a model for the occupant restraint system of an A-class car is built based on MADYMO and its effectiveness is verified by simulation and test. Then on the basis of the model for vehicle frontal crash verified, a frontal crash model with tandem airbag is established, on which a frontal crash simulation is conducted. Finally the parameters of tandem airbag are optimized by orthogonal test. The results show that the tandem airbag optimized makes the WIC for the occupant large in stature reduce by 30.7% compared with traditional airbag, significantly enhancing the safety performance of occupant restraint system.
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    A Research on Nonlinear Vibration Characteristics of Piecewise Stiffness Dual Mass Flywheel
    Shi Wenku, Chen Long, Chen Zhiyong , Ding Ji
    2019, 41 (4):  417-425.  doi: 10.19562/j.chinasae.qcgc.2019.04.009
    Abstract ( 361 )   PDF (2473KB) ( 430 )   Save
    The nonlinear vibration characteristics of the dual mass flywheel with piecewise linear stiffness during torsional vibration are studied in this paper. Firstly, the mathematical model of the dual-mass flywheel piecewise linear system is established. The average method is used to obtain an approximate solution of the system response and the amplitude-frequency characteristic function under the periodic excitation. Then for the actual dual mass flywheel, the influence of each parameter on the amplitude-frequency characteristics is analyzed. Finally, the damping performances of single-stage stiffness and two-stage stiffness dual-mass flywheel under different working conditions are compared and analyzed. The results show that the average method is applicable to the nonlinear vibration analysis of the dual-mass flywheel and the system amplitude-frequency characteristic curve has the characteristics of turning to high frequency at the segment. Nonlinear characteristics can reduce the resonance peak of the system. The simulation results also show that the two-stage stiffness dual-mass flywheel has smaller second mass speed fluctuation and angular acceleration than the single-stage stiffness flywheel under ignition and flameout conditions.
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    Remaining Useful Life Prediction of Power-Shift Steering Transmission Based on Competing Failures
    Yan Shufa, Ma Biao , Zheng Changsong
    2019, 41 (4):  426-431.  doi: 10.19562/j.chinasae.qcgc.2019.04.010
    Abstract ( 378 )   PDF (717KB) ( 375 )   Save
    Remaining useful life(RUL) prediction is the key issue to fault diagnosis and health management of mechanical transmission system. As a complex time-varying electromechanical system, the power-shift steering transmission (PSST) often has many failure modes and processes in the running process under high speed and heavy load, and the interaction between different failure modes is competition failure. However, in current RUL prediction studies of PSST, there is no study considering the competing failure. In this paper, the RUL prediction method of PSST is presented based on competing risks of degradation failure and random failure. First, the multi-dimensional degradation monitoring data is integrated by the state space model and robust kernel principle component analysis (PCA) to obtain the degradation index of the whole machine. Then, the degradation model is established based on Wiener process, the random failure model is established based on Weibull distribution, and the competition failure model of PSST is further established considering the correlation between the degradation failure and random failure. Finally, the model's parameters are estimated by the maximum likelihood estimation (EML) method and the RUL prediction of PSST is realized. The experiments validate the proposed method, and the results indicate that the proposed method can objectively describe the reliability variation law of the device and can effectively improve the accuracy of RUL prediction.
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    A Simulation Study on Power Assisting Characteristics of Full Range Vehicle Mass EPS System for Commercial Vehicles
    Li Yaohua, Feng Qianlong, Zhang Yangsen, Nan Youfei , Ou Pengfei
    2019, 41 (4):  432-439.  doi: 10.19562/j.chinasae.qcgc.2019.04.011
    Abstract ( 236 )   PDF (4401KB) ( 608 )   Save
    In order to improve the steering performance of commercial vehicles with big change of load, the electric power steering (EPS) system with full range vehicle mass power assisting characteristics is proposed. Its assisting characteristics and control strategy are studied. Through co-simulation of TruckSim and Simulink, the influence of full range vehicle mass EPS system, traditional single mass EPS system and EPS-free system on vehicle performance are compared. Simulation results show that the EPS system with full range vehicle mass assisting characteristics can provide better steering lightness and handling stability for commercial vehicles. It can reduce the impact of vehicle mass on the steering performance, so as to bring drivers clearer sense of road.
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    A Research on Adaptive Lane Change Warning Algorithm Based on Driver Characteristics
    Liu Zhiqiang, Han Jingwen , Ni Jie
    2019, 41 (4):  440-446.  doi: 10.19562/j.chinasae.qcgc.2019.04.012
    Abstract ( 299 )   PDF (2367KB) ( 559 )   Save
    A lane-changing hazard perception model based on the behavior characteristics of the driver is established, and a new algorithm is proposed with on-line parameter identification and adjustable threshold. By using the fuzzy logic method, the influence of the surrounding vehicles on lane change is determined by the speed correlation degree, the safety factor and the lateral deviation to modify hazard perception model parameters. Then the model parameters are on-line identified by recursive maximum likelihood estimation, and the real-time risk assessment value is obtained. Finally, based on the information entropy, the optimal alarm threshold is searched, and the real-time evaluation value is compared with the alarm threshold to judge the alarm state of the system. Verification results using natural driving behavior data from real-car experiments show that the accuracy of the adaptive warning model is 92.1% and the time to predict the state of danger can be advanced by 0.3-1s , which accords with the psychological expectation and practical operating characteristics of the driver.
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    A Research on Calibration Method of Tracked Vehicle Test Bench Load Simulation
    Lü Haoliang, Wang Zhe, Wu Penghui, Zhou Xiaojun , Yang Chenlong
    2019, 41 (4):  447-454.  doi: 10.19562/j.chinasae.qcgc.2019.04.013
    Abstract ( 237 )   PDF (3617KB) ( 398 )   Save
    To accurately reproduce the road load and inertia load in tracked vehicle test bench, the calibration method for test bench load simulation accuracy is studied in this paper. Firstly, the dynamic model of tracked vehicle under complex driving conditions is analyzed. The equivalent inertia model of whole vehicle is established, and the loading model of motor is established by speed tracking method. Then in order to study the error of system inertia simulation under this model, a method of calibrating electrical simulation inertia with standard inertia flywheel set is used to calibrate the system simulation accuracy. In the calibration process, the effect of the resistance moment of the system on the calibration results is eliminated and the influence of original mechanical inertia is taken into account. The response time of inertia simulation is analyzed in both steady state and dynamic states. The calibration results show that the system has high simulation accuracy. The validity of the calibration method is confirmed by the test results of the calibrated system vehicle.
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    A Study on Equivalent Pavement Adhesion Mechanism of Vehicle's Inertial Test Bench with Dual-drum
    Xing Zhichao, Wang Guoye, He Changran, Gong Zhangpeng, Zhou Liyang , Xu Dongxin
    2019, 41 (4):  455-461.  doi: 10.19562/j.chinasae.qcgc.2019.04.014
    Abstract ( 176 )   PDF (1504KB) ( 724 )   Save
    In this paper, a distributed measurement and control system based on CAN/PCI bus is established for a dual-drum inertia test bench, which can be used to test and check vehicle security and power performance. Based on the designed inertia test bench, an algorithm for calculating the peak adhesion coefficients in different road conditions by changing the placement angle between wheel and dual drums is proposed. Based on dynamic analysis of single wheel during braking process, the dynamic model of single-wheel test bench system is established. According to the dynamic model, the equivalent adhesion mechanism of road adhesion with variable placement angle and peak adhesion coefficient is obtained. By Matlab/Simulink, the simulation model of single-wheel test bench system is built and the algorithm of equivalent road adhesion coefficient is verified. Through the designed single wheel-test bench system, the real-time longitudinal force and sliding rate of the wheel in small sliding area are obtained and the equivalent peak adhesion coefficient is estimated in real time based on Slip-slope theory. The results show the validity and feasibility of the proposed mechanism and the algorithm.
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    Fusion of Accident Reconstruction Results Obtained From Multiple Models Based on Evidence Theory
    Zou Tiefang, Liu Yong, He Fenglin , Li Hua
    2019, 41 (4):  462-467.  doi: 10.19562/j.chinasae.qcgc.2019.04.015
    Abstract ( 199 )   PDF (769KB) ( 471 )   Save
    The evidence theory is introduced in this paper for the fusion of multi-models’ results, two methods for evaluating the value of basic probability assignment (BPA) are explored and the fusion scheme when model’s results are intervals is given. The demonstration of a real case indicates that when the first value evaluation method for BPA is chosen, the essence of fusion is to average multi-models’ results, while the second method can get more objective results of fusion due to the introduction of experts’ opinions. When the models’ results are intervals, though the results of fusion are complicated but they contain more information. This study provides a solution for the scientific description of multi-models’ results, and gives supports for further enhancing the objectivity of reconstruction results.
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    Theoretical and Simulation Study on the Static and Dynamic Axial Crushing of Ridgeline Strengthened Thin-walled Square Tubes
    Zheng Yuqing, Zhu Xichan , Ma Zhixiong
    2019, 41 (4):  468-474.  doi: 10.19562/j.chinasae.qcgc.2019.04.016
    Abstract ( 197 )   PDF (2601KB) ( 420 )   Save
    This paper aims to study the static and dynamic axial crushing of ridgeline strengthened thin-walled square tube. Firstly, the choosing method of the energy-equivalent flow stress in the formula of static mean crushing force for ridgeline strengthened square tube and its effects on theoretical prediction results are analyzed. Then the formula for dynamic mean crushing force is derived based on Cowper-Symonds empirical formula. Meanwhile, the finite element models for 440A original and ridgeline strengthened square tubes subjected to static and dynamic axial crushing are built with Hypermesh 9.0, and a simulation is conducted to reconstruct its plastic deformation process with the fluctuation of crushing force, and the results well agree with theoretical values with a maximum deviation less than 4%. Finally, several 35 steel square tubes with plastic strain strengthened ridgelines are fabricated for conducting static crushing test, verifying the validation of the static mean crushing force formula with a 7.1% derivation from the theoretical value. This study provides some references for the strength design of ridgeline strengthened thin-walled square tubes and their application in vehicle body structures.
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    A Research on a New Type of Eddy-Current Retarding & Heating System for Electric Bus
    Ye Lezhi, Liang Chen, Li Desheng , Liu Zenggang
    2019, 41 (4):  475-480.  doi: 10.19562/j.chinasae.qcgc.2019.04.017
    Abstract ( 172 )   PDF (2036KB) ( 345 )   Save
    In view of the significant decline in the driving range of battery electric vehicle during heating in winter, a new method for efficient utilization of braking energy is proposed. A new type of eddy-current retarding & heating system for electric bus is designed. Through the studies on the braking stability of electro-mechanic-magnetic integrated braking system and the mechanism of eddy-current retarding and heating, the braking control strategy for the system is established, and the simulation and bench test are conducted on the system. The study provides a new idea for enhancing the driving range and safety of electric bus.
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