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  • 2019, Vol. 10 No. 2 Published on:29 June 2019 Previous issue    Next issue
    Progress & Prospects
    Key technique of deep neural network and its applications in autonomous driving
    LI Shengbo, GUAN Yang, HOU Lian, GAO Hongbo, DUAN Jingliang, LIANG Shuang,WANG Yu, CHENG Bo, LI Keqiang, REN Wei, LI Jun
    2019, 10(2):  119-145.  doi:10.3969/j.issn.1674-8484.2019.02.001
    Abstract ( 927 )   PDF (2819KB) ( 5056 )  

    Autonomous driving is one of the three major innovations in automotive industry. Deep learning is a crucial method to improve automotive intelligence due to its outstanding abilities of data fitting, feature representation and model generalization. This paper reviewed the technologies of deep neural network (DNN) for autonomous vehicles, which covered its history, main algorithms and key technical application. The historical timeline of DNN, its “Unit-Layer-Network” architecture, and two types of representative models were introduced. The training algorithms centered on back propagation (BP), labelled datasets and free-source frameworks for deep learning were summarized, followed by the introduction to computing platforms and model optimization technologies. Finally, the applications of DNN in autonomous vehicles were discussed, including object detection and semantic segmentation, hierarchical and end-to-end decision-making, longitudinal and lateral motion control. The applicable methods and future works for different key problems of DNN in autonomous vehicles were pointed out.

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    Development trend of internal combustion engines in the revolution of automotive powertrain
    HAN Zhiyu, WU Zhenkuo, GAO Xiaojie
    2019, 10(2):  146-160.  doi:10.3969/j.issn.1674-8484.2019.02.002
    Abstract ( 488 )   PDF (2445KB) ( 1194 )  

     The progresses achieved in the past 30 years are reviewed in the technologies and products of light-duty automotive gasoline engines. The revolutionary diversifications happened in the past 20 years of automotive powertrains are also summarized including hybrid, pure electrical and fuel cell ones. And the future development trend is foreseen of internal combustion engines for light-duty vehicle applications. Remarkable advances have been achieved in the gasoline engine technologies and products indicated by the significant improvements in the power density, thermal efficiency (fuel economy), emission levels and so forth. Based on the predictive researches of the diversified powertrain options, it is concluded that internal combustion engines will continue to play important roles in the future automotive, and at least 60% of light-duty vehicles will be equipped with internal combustion engines in the future 30 years. However, the dominant role of an engine will gradually change such that a car powered by a single engine will shift to be powered by a combination of an engine and a motor or motors. The role of an engine will change from Solo to Duo. The future development of light-duty vehicle gasoline engines will be focused on the design of hybrid-dedicated engines, improvement of thermal efficiency and the application of low-carbon fuels such as natural gas. The technological means are finally discussed for improving the engine’s thermal efficiency up to 45%.

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    Automotive Safety
    Active control of steering-by-wire of vehicle based on fractional-order PID theory
    ZHAO Shuen, LIU Qiuyang
    2019, 10(2):  161-168.  doi:10.3969/j.issn.1674-8484.2019.02.003
    Abstract ( 246 )   PDF (2154KB) ( 589 )  

     An active control method of steering-by-wire (SBW) was proposed based on a fractional-order proportional-integral-differential (PID) theory to have a better vehicle running stability. The authors stablished a Simulink dynamic model of the SBW system, and designed a control strategy of state-tracking-correction with yaw-rate-feedback using an ideal variable transmission ratio curve with constant yaw rate gain. Some rationalization and parameter tuning were processed out by using an Oustaloup filter and a particle swarm optimization algorithm. The automobile SBW with a fractional-order PID controller was analyzed by an off-line simulation using a Carsim/Simulink joint simulation under the conditions of high-speed double-shift line and the conditions of fish hook. The results show that the fractional order PID controller reduces the yaw angular velocity by 4.7% and 9%, reduces the lateral acceleration by 6.3% and 7.7%, and reduces the sideslip angle of center of mass by 9.8% and 19.5%, compared with the traditional PID control and with the fuzzy control. Therefore, the controller has better SBW active control performance.

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    Differential power steering control for in-wheel motored electric vehicle based on variable universe fuzzy PID
    ZHANG Zhiyong, TANG Lei, HAO Wei, YUAN Quan
    2019, 10(2):  169-177.  doi:10.3969/j.issn.1674-8484.2019.02.004
    Abstract ( 169 )   PDF (3336KB) ( 608 )  

    A differential power steering control method was proposed based on variable universe fuzzy proportional-integral-derivative (PID) to improve the steering lightness of an in-wheel-motored electric vehicle. A steering system model and an ideal power assist characteristic model were established to obtain the ideal steering wheel torque during vehicle steering. According to the deviation of steering wheel torque and the change rate of the deviation, the PID control parameters were adjusted and the torque distribution control of the four wheels were realized. PID was used to control the slip rate of the wheels to avoid excessive wheel slip. Numerical simulation based on CarSim and MATLAB/Simulink software was used to analyze the control performance. The results show that the vehicle steering lightness improvement under variable-domain fuzzy PID control is 43.5%, and the error rms of the yaw rate is 0.212 rad/s. The proposed control method can improve the accuracy of steering wheel torque tracking ideal torque, and effectively realize the wheel slip rate control.

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    Optimized algorithm for vehicle forward collision pre-warning time considering road adhesion coefficient
    YIN Xiaoqing, WANG Hao, MO Yudi, HU Panfeng
    2019, 10(2):  178-183.  doi:10.3969/j.issn.1674-8484.2019.02.005
    Abstract ( 244 )   PDF (1676KB) ( 652 )  

     A time to collision (TTC) warning method was proposed considering road adhesion factor and vehicle driving state to effectively avoid collision accidents and improve the accuracy and efficiency of forward collision pre-warning time (CPWT). An improved dual-exponential model was used to obtain the vehicle adhesion coefficient under different road conditions. A CPWT model was constructed considering road adhesion factor, according to the different driving states of the front vehicle, such as static, uniform speed, uniform acceleration, and variable acceleration linear motion. The CPWTs of car-following forward were simulated by using MATLAB/Simulink. The CPWT algorithm was used to analyze the CPWT for the front vehicle and the following vehicle driving on the snowy roads, wet roads and dry roads and in different driving states. The results show that the CPWT model is more reasonable and effective compared with other collision pre-warning methods. Therefore, the CPWT method can provide a theoretical support for automatic driving and vehicle warning.

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    Numerical research on characteristics of power battery impact wave of new energy vehicle
    ZHU Haitao, ZHANG Xianglei, YANG Jianlin, ZHANG Bing
    2019, 10(2):  178-183.  doi:10.3969/j.issn.1674-8484.2019.02.006
    Abstract ( 210 )   PDF (2222KB) ( 297 )  

    The mechanical impact response datum of the power batteries were collected and the average impact strength curves were obtained in the collision of new energy vehicles to determine the impact test conditions of power battery for new energy vehicles. The average impact strength curve was processed mathematically by means of equivalent trapezoidal wave and least square method. The characteristic value and tolerance of impact strength were obtained and the test conditions were compared with ISO 12405-3. The results show that independent waveforms corresponding to collision patterns should be used to test the power batteries for new energy vehicles in China, which was different from ISO standard in the upper and lower limit and time history of shock wave shape.

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    Target positioning algorithm for automotive radar based on compressed sensing in spatial domain
    CHEN Zhen
    2019, 10(2):  192-199.  doi:10.3969/j.issn.1674-8484.2019.02.007
    Abstract ( 376 )   PDF (2524KB) ( 419 )  

    Millimeter wave automotive radar (MWAR) is an important sensors in the advanced driver assistance system (ADAS) and the automatic driving system (ADS). To promote the distance resolution by the MWAR, and to reduce the snapshot number when estimating the angle of the target vehicle, this paper proposed a positioning algorithm of automotive radar based on compressive sensing. The method analyzes from the perspective of spatial domain, considering the sparse distribution among the targets in the spatial domain of the whole space in the automotive radar detection range to estimate the distance, the velocity and the angle of the target vehicles. Compared to conventional vehicle-mounted radars, matched filters cannot distinguish similar targets. The compressed-sensing radar can distinguish adjacent targets. The results show that when a snapshot number is 1, the algorithm estimates the target angle with a resolution of less than 4°. The resolution is better than that by the Music (multiple signal classification) algorith

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    Development of 24 GHz blind spot detection and lane change assist radar system
    CHEN Liwei, TONG Panpan, XIONG Min, BAI Jie, HUANG Libo, BI Xin, ZHAO Tianhao, TAN Bin
    2019, 10(2):  200-210.  doi:10.3969/j.issn.1674-8484.2019.02.008
    Abstract ( 248 )   PDF (2530KB) ( 618 )  

     A 24 GHz radar system with blind-spot-detection (BSD) and lane-change-assist-radar (LCA) was proposed to alert driver of possible dangerous situations. Under defined alarm conditions, designed a waveform of the radar system, and simulated the signal generation and signal processing algorithms of the radar by using the ADIsim PLL, SystemVue and Matlab software. Designed and fabricated a hardware system that was consisting of a radar housing, a signal processing circuit board, an isolated signal processing circuit board, and a radar RF antenna circuit board. A real vehicle test was carried out on the BSD and LCA function of the radar system. The test data showed that the radar system warns under dangerous conditions and does not warn under other conditions. Therefore, the developed radar system complies with relevant international standards.

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    Automotive Energy Efficiency & Environment Protection
    Parameter optimization and energy management of hybrid energy storage system based on battery life
    WANG Feng, LUO Yutao
    2019, 10(2):  211-218.  doi:10.3969/j.issn.1674-8484.2019.02.009
    Abstract ( 227 )   PDF (1947KB) ( 320 )  

     A method of parameter optimization and energy management was proposed for a hybrid energy storage system (HESS) to prolong the life of lithium-ion batteries. The HESS parameters of a target hybrid electric vehicle (HEV) were optimized by using a dynamic programming algorithm based on a life model of lithium-ion batteries established by the authors under driving cycles to obtain the parameters of lithium-ion batteries and super-capacitors at the lowest cost. A fuzzy controller was designed to manage the energy of the HESS with input parameters of the vehicle speed, the vehicle power requirement, and the state of energy (SOE) of a super-capacitor. And a prototype was made for experimental verification. The results show that the battery lives are prolonged by 18.0%, 31.2% and 38.3% respectively under the regulations of the new Europe driving cycle (NEDC), the urban dynamometer driving schedule (UDDS) of USA, and the Economic Commission for Europe (ECE) of UN, and the cost per kilometer decreases by 17.2%.

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    Parameter-adaptive mass identification algorithm of electric vehicles
    XIE Hui, ZHANG Ning
    2019, 10(2):  219-225.  doi:10.3969/j.issn.1674-8484.2019.02.010
    Abstract ( 213 )   PDF (1838KB) ( 571 )  

     A vehicle mass estimation algorithm, which can adapt to the variation of air resistance, windward area and transmission ratio, was proposed to reduce the dependence of mass estimation model on vehicle parameters for electric vehicle (EV) in engineering applications. The reduction of transmission ratio and slope were identified on the base of the vehicle operation information obtained through vehicle terminal. The air density, windward area and wind resistance coefficient extracted from air resistance were regarded as a parameter, which was identified by the extended Kalman filter algorithm together with the vehicle mass. The results show that the average error of quality parameter identification is 3.74% under different vehicle mass and road environments. The proposed algorithm can estimate vehicle mass in real time with good adaptability to variation of vehicle and environment parameters.

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    Automotive Energy Efficiency & Environment Protection
    Modal analysis of vibration test on plastic fuel tank with or without water#br#  
    WANG Shuyu, HOU Zhichao, SU Weidong, WANG Shuai
    2019, 10(2):  226-232.  doi:10.3969/j.issn.1674-8484.2019.02.011
    Abstract ( 207 )   PDF (2070KB) ( 507 )  

    The vibration characteristics of plastic fuel tanks during the actual vehicle operation were measured in a test bench designed with modal analyses for a light-weight vehicle designing. The vibration modal of the fuel tank were compared and analyzed by using a hammering method for dry mode and the wet mode with different water contents under free suspension state and installation state. The test bench has sufficient rigidity to ensure measure the vibration characteristics of the fuel tank in the frequency band of interest, and to regenerate the constraints to the fuel tank in a actual running vehicle. The influence of boundary conditions on fuel tank vibration characteristics was analyzed with the norms of frequency response function, modal frequency and vibration mode, modal phase collinearity (MPC) and mean phase deviation (MPD). And the influence of the liquid filling amount on the modal frequency and vibration mode of the fuel tank in the installed state was focused on analysis. The research results show that as the water filling increases, the natural frequency of the fuel tank decreases with a changing vibration mode.

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    Lightweight design of lithium-ion power battery pack based on multi-disciplinary optimization
    YU Chenglong, LIU Ying, QIAO Xin
    2019, 10(2):  233-240.  doi:10.3969/j.issn.1674-8484.2019.02.012
    Abstract ( 349 )   PDF (1990KB) ( 385 )  

    A finite element model (FEM) for a lithium-ion battery pack of an electric vehicles (EV) was established according to the China Standard GB/T 31467.3 “Safety requirements for lithium ion power batteries for electric vehicles” with analyzing noise vibration harshness (NVH), structural durability and crash safety to realize lightweight and structural durability. The weld spot fatigue analysis was carried out with the random vibration load in freguency domain being equivalent to the random signal in time domain. A multi-disciplinary automatic sample calculation-process was built to generate an approximate model with an optimization analysis. The predicting fatigue life was consistent with the experimental results. The results show that by using a multi-disciplinary optimization-design, the battery pack mass reduces by 4.0 kg with a rate of 6.5% with the pack modal-number reducing by 13.4%, while the maximum weld spot damage rate is 0.52, which meets the requirements of the target, and without any failure in the experiments. Therefore, the multi-disciplinary optimization-design can quickly and accurately find the solution of global optimization.

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    Nozzle internal flow and primary breakup characteristics of diesel spray during initial stage
    WANG Ziman, DAI Xiaoyu, LEE Chia-fon, WU Han, LI Yanfei
    2019, 10(2):  241-248.  doi:10.3969/j.issn.1674-8484.2019.02.013
    Abstract ( 208 )   PDF (2222KB) ( 396 )  

     Nozzle internal flow significantly affects the spray breakup, combustion and emissions of an internal combustion engine. The characteristics of internal flows in a nozzle and the corresponding diesel spray primary breakup during the initial stage were investigated through a single transparent nozzle by using a high-speed microscopic technique to capture the interaction process between gas-bubbles and liquid films. Numerical simulation was used to analyze the coupling process between the bubbles and thin fuel films with probing the velocity field and clarify the formation mechanism of the spray formation and its breakup process. The results show that the residual liquid fuel volume, the fuel properties, the strength of pressure shock wave, and the interaction between gas-bubbles dominate the spray morphology. Under low injection pressure, the gas-bubbles store less energy, and lead to the formation of mushroom-shaped spray. When injection pressure is high, the gas-bubbles save more energy, effectively promote spray atomization, and form a drum-shaped spray.

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