Table of Content

25 May 2018, Volume 40 Issue 5 Previous Issue    Next Issue

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A Study on Starting Control Strategy and Parameter Optimization Huang Ya,Lin Xuedong,Duan Chunli,Yu Lan,Wang Shuangyin 2018, 40 (5):  501-507.  doi: 10.19562/j.chinasae.qcgc.2018.05.001 Abstract ( 288 )   Save On the basis of 20T high pressure common rail diesel engine and Bosch second generation high pressure common rail fuel injection system, the starting control strategy is formulated, and the parameters of starting control strategy including starting adjustment torque constant, fuel injection proportion and injection timing are optimized by tests in the condition of constant fuel quantity injected. The results show that when the starting adjustment torque constant is set to 25N·m, the combustion and heat release centers of gravity are in the vicinity of top dead center, leading to a sufficient combustion of fuel. As the fuel injection proportions of two preinjections and one maininjection are set to 20%-20%-60%, the starting time can be shortened and the maximum cylinder pressure in starting process is more stable. The optimal injection timing is determined by orthogonal experiment, effectively reducing the mean square deviation of maximum cylinder pressure in starting cycle and enhancing the thermal efficiency of the first starting cycle. After engine is optimized, the starting time is shortened, the smoothness and stability of starting are improved, the fuel burns more sufficiently, thus resulting in an overall enhancement in starting performance of engine. Related Articles | Metrics

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Crashworthiness Optimization of Automotive Thin-walled Structure with Functionally Graded Strength#br# Zhao Xi, Chen Shuai, Ying Liang, Hou Wenbin, Hu Ping 2018, 40 (5):  508-514.  doi: 10.19562/j.chinasae.qcgc.2018.05.002 Abstract ( 252 )   Save The crashworthiness of an automotive thinwall structure with functionally graded strength (FGS) is simulated by finite element method in this paper. Firstly taking the peak crash force F and the specific energy absorption E of the structure during crash as evaluation indicators to analyze the effects of thickness t, the strength s of impacting end and gradient index m on the crashworthiness of the structure. An approximate relationship between performance parameters （F andＥ）and design variables (m, t and s) is established by response surface method, and a multiobjective optimization is conducted on the structure to obtain the optimal Pareto frontier. Then with consideration of the instability of technological factors, three characteristic points on Pareto frontier are chosen to analyze the robustness of optimal designs and it is found that the robustness is the best when m<05 (in this case s and t should take minimum value). Finally a frontal crash simulation on the front longitudinal beam of a pickup truck is performed with three materials, i.e. original material with lowstrength homogeneous property, highstrength homogeneous material and FGS material. The results show that FGS thinwall structure has better performance than the traditional design with original material in respects of cab deceleration, front bulkhead intrusion and specific energy absorption with less mass, so has the best overall performance. Related Articles | Metrics

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A Study on Drowsy Driving State Based on EEG Signals Chen Jichi, Wang Hong, Wang Qiaoxiu, Hua Chengcheng, Liu Chong 2018, 40 (5):  515-520.  doi: 10.19562/j.chinasae.qcgc.2018.05.003 Abstract ( 366 )   Save For rapidly and accurately detecting drivers drowsiness, a drowsiness detection method based on brain network features is proposed in this paper. Firstly a real driving experimental environment is selected to collect the electroencephalogram (EEG) signals of drivers in real time and the wavelet packet decomposition and reconstruction are conducted on the EEG signals collected with their rhythm signals extracted. Then, the connection matrix is constructed by calculating the phase lag index of each lead and the brain network features of each rhythm are extracted. Finally through the artificial neural network regression analysis on the subjective drowsiness of driver and the features extracted, the complicated relationship between them is obtained with a correlation factor of 90.27%. The results verify the feasibility of drowsiness assessment method based on functional connectivity, opening up a novel way for brain dynamics modeling under different mental states. The method proposed uses fewer electrodes to detect drowsiness by wearing EEG equipment so is handy and economical, having a great significance to the development of driver drowsiness detection system. Related Articles | Metrics

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Multiobjective Uncertainty Optimization of Occupant Restraint System Liu Xin, Fu Qing, Yin Lairong, Zhang Zhiyong1 2018, 40 (5):  521-527.  doi: 10.19562/j.chinasae.qcgc.2018.05.004 Abstract ( 248 )   Save With consideration of the influence of uncertain parameters of occupant restraint system on occupant safety, a multiobjective uncertainty optimization technique for occupant restraint system is proposed based on the combination of nonlinear interval number programming (NINP) and approximate model with locallyrefined mesh. The numerical model for occupant restraint system is corrected according to the results of real vehicle frontal crash tests, and the uncertainty optimization problem is converted into a deterministic optimization problem by using interval order relations. Intergeneration projection genetic algorithm (IPGA) and micro multiobjective genetic algorithm (μMOGA) are adopted to seek for Pareto solution set meeting the protection performance requirements of occupant restraint system. The results demonstrate that the proposed method can effectively obtain the optimal matching parameters of occupant restraint system with consideration of the effects of uncertainty and hence ensure the safety of vehicle occupants, having an extensive prospect of engineering application in the field of vehicle safety. Related Articles | Metrics

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Crashworthiness Design of Supporting Structure for theSteering Column of a Mini Electric Vehicle Zheng Yuqing, Zhu Xichan, Dong Xueqin, Zhao Rutao, Ma Zhixiong 2018, 40 (5):  528-535.  doi: 10.19562/j.chinasae.qcgc.2018.05.005 Abstract ( 220 )   Save According to the requirements of GB11557—2011, an energy absorbing and supporting structure for the steering column of a mini electric vehicle is designed, which consists of two thinwalled beam channels with a central V notch, and its ultimate strength in plastic deformation phase can be controlled by V notch parameter c and intersection angle θ. The results of simulation show that the crash force of human body module reduces nonlinearly with the increase of c and θ . The comparison between numerical simulation and impact test when c=24mm indicates that they are almost identical in plastic deformation mode and their crash force curve well agrees with each other, with a deviation of only 6 % for the peak crash force of humanbody module. The strength and impact energyabsorbing capacity of new supporting structure well conform to crashworthiness design requirements in both impact test and real vehicle driving. Related Articles | Metrics

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A Research on Thermalflow Twoway Coupling Analysis Technique for Drum Brakes of Commercial Vehicles Chen Jing, Zhang Qun, Chen Ying, Han Yepeng, Liu Yanhe, Han Zhongtian 2018, 40 (5):  536-541.  doi: 10.19562/j.chinasae.qcgc.2018.05.006 Abstract ( 290 )   Save A numerical simulation method for thermalflow twoway coupling with control data exchange and mapping interpolation functions is developed for generalpurpose drum brake and is applied to the simulation of the braking on normal road with drum brake. Then the results of simulation are compared in accuracy with the temperatures measured in bench test. The results show that the thermalflow twoway coupling analysis method developed is advanced in technical means with a analysis accuracy higher than 83%, meeting engineering requirements with engineering application and dissemination values. Related Articles | Metrics

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A Study on Economic Speed in Lanechange Maneuvers of Intelligent Vehicles Jin Hui,Ding Feng 2018, 40 (5):  542-546.  doi: 10.19562/j.chinasae.qcgc.2018.05.007 Abstract ( 236 )   Save This paper aims at realizing economic speed programming in the lanechange process of intelligent vehicles. Based on transient fuel consumption model, vehicle dynamics model and the road curvature information in the process of lanechange, the trajectory of vehicle with economic speed is obtained by using dynamic programming algorithm. The results of Matlab/Simulink and CarSim cosimulation show that compared with cruise control algorithm, dynamic programming algorithm can reduce fuel consumption by around 8%. The adoption of the technique proposed can enhance fuel economy while assuring the safe driving of intelligent vehicle, providing the decisionmaking basis of speed control in the lanechange process of intelligent vehicles. Related Articles | Metrics

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Modeling and Hierarchical Control of Vehicle ACC System Zhang Liangxiu, Wu Guangqiang, Guo Xiaoxiao 2018, 40 (5):  547-553.  doi: 10.19562/j.chinasae.qcgc.2018.05.008 Abstract ( 365 )   Save In order to improve the function of adaptive cruise control (ACC) system, a modeling and hierarchical control method for ACC system is investigated in this paper. Firstly, a 14 DOF vehicle dynamics model is established with considerations of longitudinal, lateral and vertical coupling characteristics, and according to the physical characteristics of electronic throttle and brake system，an actuator model, which can accurately track the desired input，is also built. Then an inverse dynamics model is set up, which includes drive / brake switching logic, inverse engine model and inverse brake model. Finally aiming at the functional requirements of ACC system, the robust lowerlayer controller accommodating different working conditions is designed by applying model matching control theory, while the upperlayer controller can get the desired vehicle following acceleration, comprehensively considering vehicle distance, relative velocity and ego vehicle acceleration based on linear quadratic optimal control theory. Simulation results show that the ACC system can make vehicle maintain good tracking and adaptive performance in different driving conditions covering acceleration, steady following and deceleration. Related Articles | Metrics

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Front Vehicle Detection with Multi source Information Based on Deep Belief Network Wang Zhangu, Gao Song, Shao Jinju, Tan Derong, Sun Liang & Yu Jie 2018, 40 (5):  554-560.  doi: 10.19562/j.chinasae.qcgc.2018.05.009 Abstract ( 203 )   Save Based on the theory of deep belief network (DBN), a front vehicle detection method by using multisource information is proposed in this paper. Firstly the joint calibration of millimeterwave radar and video camera is conducted and the transformation relation between two sensor coordinate systems is determined. Then through the preprocessing of millimeterwave radar data, the label classification of obstacles is accomplished, and the data of front vehicle objects and other types of obstacles are obtained. Next the data are trained by utilizing DBN and the preliminary identification of front vehicles is performed. Finally the verification windows for front vehicle identification are obtained according to the statistical data on the width and height of common vehicles. Test results show that with the method proposed, the correct rate of front vehicle identification is 912% and the total processing time for single frame image is 37ms, effectively raising the realtime processing speed of the system, in particular, it has good detection results for the vehicles in adverse circumstances like overcast, dark night, light rain, fog or haze, meeting the requirements of accuracy and stability for assisted driving. Related Articles | Metrics

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Experimental Study on a SemiActive Magnetorheological Suspension Peng Zhizhao, Zhang Jinqiu, Zhang Jian, Fu Xiaowei 2018, 40 (5):  561-567.  doi: 10.19562/j.chinasae.qcgc.2018.05.010 Abstract ( 217 )   Save Aiming at the complexities of control strategies design and the inversemodel solution of magnetorheological (MR) damper in MR semiactive suspension, three typical switch control strategies, i.e. skyhook (SH) control, SHADD (acceleration driven damper) control and frequency domain control (FDC) are adopted to conduct a contrastive test for semiactive vibration control on a quarter vehicle suspension test bench based on a MR damper with parallel bypassing orifices. The results indicate that switch strategies combining with the special MR damper can effectively suppress suspension vibration with simple control process, having a good practical application value. Related Articles | Metrics

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Adaptive Fuzzy Sliding Mode Control for a Novel Steering by wire System Chen Xinbo, Luo Jie, Hang Peng, Fang Shude, Luo Fengmei 2018, 40 (5):  568-574.  doi: 10.19562/j.chinasae.qcgc.2018.05.011 Abstract ( 211 )   Save To achieve the steering angle tracking performance of a novel steeringbywire system, an adaptive fuzzy sliding mode control (AFSMC) scheme is proposed. Traditional sliding mode control needs to get the system disturbance in advance, while AFSMC can estimate system disturbance in real time by online fuzzy adaptive system, and hence weaken the switching signal in control law, reducing the conservativeness and chattering phenomena of control system. Simulation results show that the steeringbywire system with AFSMC has satisfying steering angle tracking performance, robustness and energy efficiency. Related Articles | Metrics

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Design and Study on a Novel Hydroelectric Energy Regenerative Suspension System Wen Guilin，Zhou Chuanghui 2018, 40 (5):  575-583.  doi: 10.19562/j.chinasae.qcgc.2018.05.012 Abstract ( 140 )   Save Aiming at the problem of suspension vibration energy recovery, a novel hydroelectric regenerative suspension system is proposed, with its structure and working principle expounded. Based on the mathematical model for energy regenerative suspension, its vibration attenuation and energy regeneration characteristics are analyzed. The feasibility of energy regenerative suspension is validated by a prototype testing with an energy recovery rate of around 423% obtained. Based on a 1/4 vehicle model, with a vehicle speed of 50km/h and a segment of Cgrade road surface as inputs, a contrast simulation is conducted on energy regenerative suspension and traditional passive suspension. The results show that energy regenerative suspension can replace traditional passive suspension for vehicle vibration attenuation and effectively recover the vibration energy of suspension while meeting the ride comfort requirements of vehicle. Related Articles | Metrics

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Vehicle State Parameter Estimation in Complicated Conditions Based on Interacting Multiple Model Algorithm Liu Gang，Jin Liqiang 2018, 40 (5):  584-589.  doi: 10.19562/j.chinasae.qcgc.2018.05.013 Abstract ( 234 )   Save In order to accurately and real time estimate the state parameters of vehicle for vehicle stability control, two vehicle models based on linear and nonlinear tire models respectively are set up. Interacting multiple models (IMM) algorithm is adopted for the switching between two models to accommodate different complicated road conditions, and squareroot cubature Kalman filter algorithm is fused into IMM one. Considering the effects of lateral acceleration and road adhesive coefficient on algorithms, fuzzy algorithm is adopted to conduct real time correction on the model transformation probability in IMM algorithm for speeding up model switching and enhancing tacking accuracy. The results of CarsimMatlab/simulink cosimulation and real vehicle test show that the algorithm proposed can achieve high tracking accuracy in vehicle state parameter estimation, speedy model switching and good robustness. Related Articles | Metrics

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An Analysis on Vibration Energy Flow for High Frequency Brake Squeal Gao Pu， Du Yongchang，Zhou Han 2018, 40 (5):  590-596.  doi: 10.19562/j.chinasae.qcgc.2018.05.014 Abstract ( 234 )   Save Based on the closedloop coupling model for brake squeal analysis and by applying the theories of vibration and modal analysis, the vibration energy of brake disc itself in both static and dynamic closedloop coupling models are calculated respectively at a modal frequency of 13kHz. Then the vibration energy flow and the vibration transmitting path in friction coupling interface are analyzed with a result showing that the dominant transmission path of vibration in coupling interface is from brake disc to brake pads. Finally, the vibration energy equilibrium analysis of brake disk verifies the reliability and correctness of related vibration energy calculation. The analyses in this paper provide a theoretical basis for the further investigation into the forming mechanism of highfrequency brake squeal. Related Articles | Metrics

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Effects of Crankshaft Offset on the Mixed Lubrication Characteristics of Piston Skirt Ning Lipu， Wang Lixin 2018, 40 (5):  597-604.  doi: 10.19562/j.chinasae.qcgc.2018.05.015 Abstract ( 228 )   Save A mixed lubrication model for the piston skirtcylinder liner system is developed to analyze the effects of crankshaft offset on piston dynamics and the lubrication performance of piston skirt. In piston dynamics model the effects of piston ring and connecting rod are considered, while the lubrication model is based on average Reynolds equation, rough surface contact model and Reynolds boundary condition, with consideration of the effect of deformation and the shearthinning effect of lubricating oil on lubrication performance. The effects of crankshaft offset on piston secondary motion and the lubrication performance of piston skirt are analyzed, the potential technical schemes for reducing the friction loss of piston are explored, and the feasibility of technical schemes proposed is verified through prototype trial production and tests. The results show that positive crankshaft offset is an effective measure to reduce the friction of piston skirt and the fuel consumption of engine. Related Articles | Metrics

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A Study on Simulation Test Method for Car Shipping on Truck Fan Lu, Li Chenyang, Wu Jiawei, Zhao Youlei, He Hai, Wu Wei 2018, 40 (5):  605-609.  doi: 10.19562/j.chinasae.qcgc.2018.05.016 Abstract ( 218 )   Save For early predicting the fatigue failure defects of vehicle in shipping process in early stage of vehicle development, a test rig for the simulation of car shipping on truck is constructed, its test method is worked out and the test is conducted. The failure mode of vehicle components in durability test is compared with that in the real process of car shipping on truck and the results verify the effectiveness of simulation test method for car shipping on truck. Related Articles | Metrics

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Lightweight Design of BIW Based on Implicit Parametric Model Wang Dengfeng, Cai Kefang, Ma Minghui, Zhang Shuai 2018, 40 (5):  610-616.  doi: 10.19562/j.chinasae.qcgc.2018.05.017 Abstract ( 241 )   Save In this paper, the idea of “CAE driven design” is introduced in the conceptdesign phase of bodyinwhite (BIW), an implicit parametric model for the BIW of a car is built by using SFECONCEPT, and the effectiveness of the model is validated by performance comparison with finite element model verified. A stepbystep optimization technique is adopted, combining with BIW performance matching and supplemented by the idea of light weigh design, to find the light weight design scheme of BIW on the premise of meeting all the static and dynamic performances of BIW to the maximum extent. The results of comparison between BIW performances before and after optimization show that with the little changes in bending stiffness and torsional stiffness (lowering by 02% and 06% respectively), the length, width and height of car body increase by 15mm, 13mm and 9mm respectively, the first order bending and torsional mode frequencies rise by 56% and 92% respectively, and the mass of car body reduces by 199kg with a lightweighting rate of 576%, achieving an apparent lightweighting results. Related Articles | Metrics

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Optimization of Car Body Assembly Structure Based on Modular Design Shan Chunlai, Li Yongcheng & Hou Wenbin 2018, 40 (5):  617-624.  doi: 10.19562/j.chinasae.qcgc.2018.05.018 Abstract ( 234 )   Save On the basis of considering the manufacturing and assembling costs, a component divide method based on graph decomposition algorithm is proposed in this paper, with a technique of multilayer selection from Pareto solution set introduced to solve the convergence problem in optimization with thicknesses as design variables. With the underbody panel of a bodyinwhite as example, the structure is divided according to the minimum manufacturable size, and with the connection relation between divided units as design variables, a simulation is conducted by using NSGAII algorithm with optimum assembly schemes obtained. Then with the assembly schemes in Pareto solution set obtained in optimization as initial solutions, from which the solutions meeting stability conditions are selected by using the technique of selection from Pareto solution introduced. Next, constraints are applied to the thicknesses within subcomponents to perform thickness optimization and the thicknesses obtained are returned back to graph decomposition for iteration until the problem converges, and the concurrent optimization of welding locations and panel thicknesses is achieved in the end. Related Articles | Metrics