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  • 2023, Vol. 14 No. 4 Published on:31 August 2023 Previous issue    Next issue
    Review, Progress and Prospects
    Technical characteristics and prospects of power transmissions for commercial vehicles under the “Carbon-Peak and Carbon-Neutrality” target
    XU Xiangyang, ZHAO Junwei, DONG Peng, WANG Shuhan, LIU Yanfang
    2023, 14(4):  395-412.  doi:10.3969/j.issn.1674-8484.2023.04.001
    Abstract ( 423 )   HTML ( 104)   PDF (4252KB) ( 5212 )  

    Commercial vehicles are an important force in road transportation and a large carbon emitter. Realizing the green transformation and development of commercial vehicles is an important breakthrough in accelerating the achievement of the “Carbon-Peak and Carbon-Neutrality” target in the automotive industry. However, policy-driven and market demand have posed new challenges and requirements for the development of commercial vehicle technology, especially with the emergence of multiple technological routes for power transmissions. This paper focuses on the application scenarios of medium and heavy trucks, light and pickup trucks, and buses under different power sources such as traditional fuel, hybrid, pure electric, and hydrogen fuel cell, and analyzes the technical characteristics, product spectrum, applicability in different scenarios, and technological development trends of power transmission systems for commercial vehicles. A new prospect is put forward for the development of power transmission technologies for commercial vehicles to provide a reference for the technical path selection and technological innovation and development of commercial vehicle transmissions.

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    Automotive Safety
    Effect of increasing age on injury risk in elderly male occupant
    TANG Youming, XIE Xiangjian, SUN Guibin, WANG Ping, ZHANG Yi, SUN Guanyu
    2023, 14(4):  413-420.  doi:10.3969/j.issn.1674-8484.2023.04.002
    Abstract ( 176 )   HTML ( 16)   PDF (1168KB) ( 84 )  

    To investigate the effect of increasing age on the injury risk of male elderly occupants, MADYMO software was used to establish multi-body dummy models combined with the human body size of Chinese 60-79 years old male elderly, based on the Hybrid Ⅲ 50-percentile male dummy. By coupling the model of occupant seat restraint system, the influence relationship between head, chest, thigh and weighted injury criteria (WIC) and age factors of male elderly occupants in 4 age groups (60-64, 65-69, 70-74 and 75-79 years old) was compared and analyzed, and a probability model of injury risk for elderly occupants with increasing age was proposed. The results showed that the HIC value of head, the integrate acceleration value, chest acceleration value and compression value, and the WIC value of comprehensive damage increase linearly with the increasing of the age of elderly occupants; When the age is over 74 years old, the chest 3 ms acceleration shows a steep index upward trend; With the increasing of age, the injury risk of male elderly occupants is significantly positively correlated with age (r > 0.97, p < 0.05).

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    Analysis on the rear passenger injuries of the 5th percentile Chinese female occupant in 100% frontal impact
    LI Haiyan, HU Jing, HE Lijuan, LV Wenle, CUI Shihai, RUAN Shijie
    2023, 14(4):  421-430.  doi:10.3969/j.issn.1674-8484.2023.04.003
    Abstract ( 142 )   HTML ( 14)   PDF (2920KB) ( 418 )  

    The damage risk of small rear passenger in frontal 100% crash test was investigated to provide reference data for improving the protection performance of vehicle restraint system. The simulation was set up based on the 100% frontal impact as specified in the C-NCAP (2021) using the validated injury bionic model with the 5th percentile Chinese female anatomical characteristics and the validated car finite element model. The injuries of the small size female passenger sitting the second row were analyzed including the head, neck, thoracic-abdomen and lumbar. The results show that the TUST IBMs F05-O model presents a good kinematics response of occupants in the 100% frontal impact. The lateral flexion movement of the head and neck around the seat belt is obviously observed because the spine of TUST IBMs F05-O model has high bio-fidelity. Head and neck injuries are severed as a result of the head contacted with the frontal seat. The chest viscous criterion (VC) value is 0.34 with a higher chest compression so that the lungs are compressed and injured. The lumbar injury index (LSI) and lumbar injury evaluation parameter (Lfx) are less than the corresponding injury threshold. The application of the fifth percentile Chinese female occupant injury bionic model with high biological fidelity to car crash simulation test has important application value for the development of intelligent cockpit and zero gravity seat, the study of vehicle active and passive safety integration, and the future digital evaluation method.

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    Driver visual load and operating characteristics under a human- machine interface mode with full-touch-screen
    WANG Chang, WANG Yifei, GE Zhenzhen, ZHAO Xia, LI Zhao
    2023, 14(4):  431-438.  doi:10.3969/j.issn.1674-8484.2023.04.004
    Abstract ( 123 )   HTML ( 7)   PDF (1507KB) ( 159 )  

    Two real road driving experimental platforms, the one with full-touch-screen Human-Machine Interface (HMI) and the other with non-full touch-screen HMI, were established to analyze the potential impact of an HMI mode with full-touch-screen on driving risk. And collected and analyzed the data on driver’s sight transfer and on hand transfer during drivers completing the same secondary task using different HMI. The results show that the total time of staring at the central control platform increases by 19.8%, 102.5%, and 39.1% compared to the traditional mode respectively, when using a full-touch-screen to perform secondary tasks such as turning on the air conditioning, adjusting the air volume, and blowing the front windshield; There is an exponential increasing relationship between the total time required to focus on the central control platform and the operation number required to complete the secondary tasks; Drivers spend more gaze time on each operation when using a full-touch-screen to perform the secondary tasks with more than 3.5 operations. These results provide a reference for the distraction evaluation of full-touch-screen HMI.

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    Active control for vehicle nonlinear suspension systems based on adaptive event-triggered mechanism
    JIA Junru, ZHENG Liming, ZHANG Zhen
    2023, 14(4):  439-447.  doi:10.3969/j.issn.1674-8484.2023.04.005
    Abstract ( 114 )   HTML ( 6)   PDF (1924KB) ( 51 )  

    An adaptive event-triggered control method was presented based on an interval type-2 fuzzy model for vehicle nonlinear active suspensions to simultaneously improve the performance of the ride comfort and saving communication resource. An interval type-2 fuzzy model of nonlinear suspension system was established to accurately characterize the nonlinear characteristics of spring and damper. An adaptive event-triggered strategy was employed, which can effectively save communication resources and ensure control performance of the system comparing with the traditional sampling communication mechanism. Based on the theory of time delay, the closed-loop system model of adaptive event-triggered control of nonlinear suspension was constructed to obtain a co-design method of the event generator and the fuzzy controller. The results show that the proposed strategy can reduce the body acceleration by 52.12%, suspension dynamic travel by 45.81%, tire dynamic load by 31.91%, and frequency of event trigger by 44.33% while ensuring the system stability and performance constraints. It has better performance and is more effective to improve the ride comfort of suspension and to realize the effective saving of communication resources compared with the existing method.

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    Comparison of driver’s out-of-position response of dummy and human models under AEB
    REN Lihai, LUO Zhiqin, CHEN Hao, JIANG Chengyue
    2023, 14(4):  448-456.  doi:10.3969/j.issn.1674-8484.2023.04.006
    Abstract ( 127 )   HTML ( 7)   PDF (2744KB) ( 659 )  

    In order to investigate the differences in driver’s out-of-position response under different braking intensities of dummy and human models, simulation experiments of dummy and human models were carried out. The driver-restraint system models of test device for human occupant restraint (THOR) dummy and total human model for safety (THUMS) were constructed, and the driver-restraint system model of active human model (AHM) was constructed by coupling the AHM of MADYMO and LS-DYNA finite element restraint system. The displacement-time history curves of the head, shoulders, chest and knees of dummy and human models were extracted, and the out-of-position difference analysis of dummy and human models and the analysis of driver’s out-of-position under different seat belt constraints were carried out. The results showed that the 3 models are within the range of the volunteer response channel with reference to the volunteer experimental data, and the AHM and THUMS have higher biological realism of out-off-position motion. Compared to standard seat belts, active pretension seat belts can effectively reduce the driver’s response to disengagement under autonomous emergence braking (AEB) conditions.

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    Intelligent Driving and Intelligent Transportation
    Differential algorithm with variable step-sizes to calculate accelerations in autonomous vehicle tests
    WEI Wenming, LIU Weiping, FAN Zhipeng, BAI Chuang
    2023, 14(4):  457-462.  doi:10.3969/j.issn.1674-8484.2023.04.007
    Abstract ( 117 )   HTML ( 6)   PDF (1581KB) ( 53 )  

    A differential algorithm was developed without using any inertial measurement unit, to calculate the acceleration of autonomous vehicles, and to reduce the test cost with a rational calculation accuracy. The calculation error was analyzed to contrast three algorithms, which had the fixed step-size, or the mean fixed step-size, or the variable step-size. The calculation results were compared with the measured accelerations in real car. The result shows that a suitable step-size improves the calculation accuracy; The calculation accuracies of the algorithms with 0.2-s or 0.3-s step-size are better than that of the algorithms with other step-sizes when using fixed step-size; The fluctuation of the calculation results by using the mean fixed step-size is smaller than that with the fixed step-size when the step-size is the same; The maximum absolute errors is 0.77 m/s2 for the fixed step-size algorithm, with being 0.64 m/s2 for the mean fixed step-size algorithm, and with being 0.46 m/s2 for the variable step-size algorithm; The average absolute errors are 93, 82, and 65 mm/s2 respectively for the fixed step-size algorithm, the mean fixed step-size algorithm and the variable step-size algorithm. Therefore, the calculation accuracy by using the variable step-size algorithm is the best among the three algorithms.

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    Stability analysis of the vehicle platoon system considering predecessor following and time-varying delay
    ZHOU Liguang, XU Hang, SHANGGUAN Xingchen, YAN Chen
    2023, 14(4):  463-471.  doi:10.3969/j.issn.1674-8484.2023.04.008
    Abstract ( 108 )   HTML ( 13)   PDF (2150KB) ( 31 )  

    In order to improve the safety of vehicle queuing, a delay-dependent stability analysis method based on Lyapunov-Krasovskii functional (LKF) was proposed to estimate the range of allowable time delay for vehicle following system with time-varying delay. For the vehicle following system with time-varying delay, a system model with double time-varying delay was established. Considering the relationship between two time-varying delay variables, LKF was constructed, and the stability criterion of the system with double time-varying delay was given after processing by matrix inequalities. The allowable range of time delay under different control parameters was calculated by MATLAB software for 4 vehicle lines. The results show that the controller gain is inversely proportional to the maximum time delay allowed by the system under the parameters of the vehicle following system; and under the same parameters, the delay is more important to the high-speed vehicle queue; The proposed stability analysis method can obtain the maximum allowable time delay to ensure the stability of the system, and provide stability criteria for designing the controller of the actual vehicle following queue.

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    Behavior decision-making model for autonomous vehicles based on an ensemble deep reinforcement learning
    ZHANG Xinfeng, WU Lin
    2023, 14(4):  472-479.  doi:10.3969/j.issn.1674-8484.2023.04.009
    Abstract ( 132 )   HTML ( 11)   PDF (1754KB) ( 247 )  

    A behavior decision-making model for autonomous vehicles was proposed based on an ensemble deep reinforcement learning method. The decision model was constructed based on the Markov decision process (MDP) theory. Three basic network models were integrated, including the Deep Q-learning Network (DQN), the Double DQN (DDQN), and the Dueling double DDQN (Dueling DDQN), by using the Standard Voting Method. Some tests and the generalization validation tests were done, for 5 vehicle driving behaviors, including the lane changing to the left, the lane keeping, the lane changing to the right, the accelerating in the same lane, and the decelerating in the same lane, in highway simulation environments under the scenarios of 3-lane, 4-lane, and 5-lane in one direction. The results show that the decision success rate of the proposed model increase 6%, 3% and 6%, respectively, compare with the other three network models. The average vehicle speed has also been improved; And the 100-round tests take less than 1 ms, which meets the requirement for real-time decision-making. Therefore, the decision-making model improves driving safety and decision-making efficiency.

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    Trajectory planning algorithm of autonomous vehicle based on multi-index coupling
    HUANG Pengcheng, PEI Xiaofei, ZHOU Honglong, CHEN Ci
    2023, 14(4):  480-487.  doi:10.3969/j.issn.1674-8484.2023.04.010
    Abstract ( 128 )   HTML ( 11)   PDF (2113KB) ( 133 )  

    Urban traffic environment puts forward higher requirements for the safety, comfort, compliance, traffic efficiency and other indicators of autonomous vehicles. A spatiotemporal coupled real-time trajectory planning method was proposed, and the above quantitative indexes were introduced into its evaluation function. The algorithm generated trajectories in a set of driving corridors, selected the optimal trajectories according to a multi-index evaluation function combining horizontal and longitudinal comfort, safety and utility, and tested them in a simulated roundabout. The results show that the acceleration curve is smooth and the maximum value is 0.66 m/s2 when comfort is the priority; The generated trajectory is deviated by 0.19 m on average to avoid collision with nearby obstacles when safety comes first; The generated trajectory has a maximum velocity of 9.97 m/s and exhibits a more positive acceleration profile when utility takes precedence. The algorithm can safely avoid dynamic obstacles while maintaining transverse and longitudinal acceleration, and the average cost of each iteration is 47.45 ms, which meets the real-time requirements.

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    Automotive Energy Efficiency and Environment Protection
    Operating characteristics under variable conditions of a scroll-compressor in CO2 air-conditioning-system for electric vehicle
    AN Zhongyan, SONG Panpan, LU Zhenbo, ZHENG Siyu, WEI Mingshan, ZHUGE Weilin, ZHANG Yangjun
    2023, 14(4):  488-495.  doi:10.3969/j.issn.1674-8484.2023.04.011
    Abstract ( 143 )   HTML ( 8)   PDF (992KB) ( 797 )  

    In order to increase the driving range of electric vehicles, the operating performances of the air conditioning system under variable conditions and the functional characteristics of the scroll compressor were investigated. The performance prediction model of a trans-critical CO2 heat pump air conditioning system coupled with a one-dimensional flow model of a scroll compressor was constructed, and the validity of the model was verified by experimental data. The differences in system performance prediction under variable operating conditions between the simplified compressor model the and one-dimensional flow model were compared, and the variation characteristics of the suction pre-compression and the asymmetric flow in the discharge process were analyzed. The results show that with a constant efficiency, the system operating characteristics index (the ratio of the system cooling capacity to the compressor power consumption) predicted by the simple compressor model, is up to 20% higher than that by the one-dimensional flow model. The compressor suction vacuum degree is the main factor affecting the degree of suction pre-compression. As the compressor speed increases from 2 500 r/min to 6 000 r/min, the degree of suction pre-compression increases by 1.92%, and the volume efficiency increases by 4.72%. The change in the throughflow area of the discharge port dominates the asymmetric pressure distribution in the discharge chamber. The reduction of the asymmetric degree of the discharge chamber pressure is beneficial to improve the compressor isentropic efficiency.

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    Fuzzy energy management strategies based on the ISSA for multiple power sources in fuel cells
    LUO Chuang, XU Liang
    2023, 14(4):  496-504.  doi:10.3969/j.issn.1674-8484.2023.04.012
    Abstract ( 118 )   HTML ( 9)   PDF (1933KB) ( 138 )  

    A Fuzzy Logic Control (FLC) method was proposed for Energy Management Strategies (EMS) to enhance the fuel efficiency of the Fuel Cell (FC) Hybrid Electric Vehicle (HEV). With a supercapacitor as an auxiliary energy source to optimize the hydrogen consumption, the power required under working conditions, the State of Charge (SOC) of the supercapacitors, and the fuel cell’s working efficiency were incorporated as input variables into the fuzzy controller to improve the fuzzy rules, considering the two states of automobile drive and braking. The Sparrow Search Algorithm (SSA) was employed to optimize the membership functions of the fuzzy controller. The circle mapping technique was utilized for initializing the sparrow population, with a random walk strategy to perturb the global optimal solution. Advisor software and the Matlab/Simulink environment were employed for modeling and conducting joint simulations. The results show that the energy management strategy reduces 29.38% and 29.88% of equivalent hydrogen consumption, specifically under the Urban Dynamometer Driving Schedule (UDDS) and the HighWay Fuel Economy Test (HWFET) operational scenarios, with decreasing the occurrence of load changes during the fuel cell’s operation, and consequently enhancing its longevity.

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    Effects of traffic scenarios on emission and fuel consumption characteristics for a heavy-duty-vehicle based on engine-in-the-loop methodology
    HUO Yongzhan, GAO Tao, WANG Xiaowei, LAO Hailiang, CHEN Xiong, ZHANG Youyuan, JING Xiaojun
    2023, 14(4):  505-512.  doi:10.3969/j.issn.1674-8484.2023.04.013
    Abstract ( 156 )   HTML ( 10)   PDF (1087KB) ( 101 )  

    To investigate the effects of traffic scenarios on emissions and fuel consumption of heavy-duty diesel vehicles. A dump truck with a maximum design total mass of 24.5 t was selected, and the engine-in-the-loop (EIL) method was used to construct vehicle, road, and driver models. Examined the fuel consumption and emission characteristics under three typical scenarios: the re-starting after a long idle with selective catalytic reduction (SCR) temperature, the congestion-related stop duration, and the vehicle load. The results show that when the SCR temperature is near the injection temperature, the SCR catalytic conversion efficiency is low during re-starting or acceleration, especially when the urea is not in the injection state, leading to high NOx emissions. After a congestion-related stop, the SCR temperature significantly decreases, and the longer the stop duration cause higher NOx emissions. Under the same stop duration, the full load scenario has significantly higher cumulative particulate matter (PN) emissions and the specific emissions compared to the no-load scenario, while stop duration has little impact on it. As the vehicle load increases, the brake-specific fuel consumption (BSFC) and the CO2-specific emissions decrease to some extent, while the cumulative PN emissions and the NOx emissions increase. The cumulative NOx emissions and the specific emissions show an initial increase followed by a decrease with the increase in vehicle load.

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    Effects of fuel injection strategy on combustion characteristics of methanol/PODEn dual-fuel compression ignition mode
    ZHANG Dingcheng, ZHANG Guangde, CHEN Shuzhi
    2023, 14(4):  513-520.  doi:10.3969/j.issn.1674-8484.2023.04.014
    Abstract ( 145 )   HTML ( 8)   PDF (1765KB) ( 140 )  

    The combustion and emission characteristics of methanol/PODEn mixed fuel under different fuel injection strategies were investigated to improve combustion efficiency and reduce pollutant emissions of a direct injection diesel engine. Based on the Computational Fluid Dynamics (CFD) and simulation analysis software Converge, three-dimensional modeling is carried out for a direct injection diesel engine with a Premixed Compression Combustion Ignition (PCCI) mode. Under the initial low-load conditions of 1 200 r/min engine speed, initial pressure of 100 kPa and initial temperature of 340.6 K were calculated. The results show that in a single injection, the peak pressure and the peak specific exothermic is greatly increased at the early injection time, the fuel utilization ratio is increased, and the main pollutants is significantly reduced; But the reaction rate becomes faster and the emission of pollution increases when the injection time is too early. With the advance of the pre-injection time, the interval between the pre-injection time and the main injection time becomes longer, and the cylinder pressure changes little, the heat release rate curve has 2 peaks, the peak value is slightly reduced, and the injection time (crankshaft angle, CA) is advanced. The mass emission of Soot, NOx and CO are decreased by 6.89%, 5.41% and 23.31% respectively, compared with each peak value. The pre-injection time and the main injection time of the optimal injection strategy are -27° and -22°.

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