Table of Content

25 August 2020, Volume 42 Issue 8 Previous Issue    Next Issue

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Optimal Control of Engine Shutdown for Power-Split Hybrid System Zhao Zhiguo, Tang Xuhui, Fu Jing, Fan Jiaqi 2020, 42 (8):  993-999.  doi: 10.19562/j.chinasae.qcgc.2020.08.001 Abstract ( 364 )   PDF (3417KB) ( 442 )   Save In order to reduce the longitudinal impact of the vehicle caused by engine start and stop during the mode transition process between e-CVT hybrid mode and pure electric mode, an optimal control strategy of engine shutdown is proposed for the power-split hybrid system. Firstly, the power-split hybrid powertrain model is established based on the Matlab/Simulink platform, and the crankshaft angle which is the most conducive to the restart of engine is determined as the optimal engine stop position. Secondly, the optimal speed trajectory during engine shutdown is designed by the dynamic programming algorithm. When the engine speed is less than 200 r/min, the motor and brake are coordinated to dynamically adjust the crank angle in real time, so that the engine stops near the optimal target position. Finally, the optimal control strategy of engine shutdown is verified by simulation and bench test. The results show that the proposed control strategy can make the engine stop within ±6° of the optimal position, ensuring the ride comfort of the vehicle in engine start and stop stages. References | Related Articles | Metrics

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An Improved Hierarchical Online Joint Estimation Method for Impedance Parameters and State of Charge of Traction BatteryHuang Ranjun, Zhou Wei, Wang Xu 2020, 42 (8):  1000-1007.  doi: 10.19562/j.chinasae.qcgc.2020.08.002 Abstract ( 212 )   PDF (7589KB) ( 119 )   Save Traditional joint estimation algorithms for the model parameters and state of charge (SOC) of the battery usually employ a two-layer architecture: one recursive estimator identifies all the model parameters and the other infers SOC. Due to the large number of parameters to be identified, these algorithms often have the problems of tedious tuning and poor robustness. In order to solve these problems, an online joint estimation algorithm of impedance parameters and SOC is proposed based on a three-layer architecture. This algorithm identifies Ohmic internal resistance and polarization parameters separately for reducing the complexity of the problem. In addition, by analyzing the dynamic characteristics of the modeling error of first order RC model, a lumped error model based on first order inertial link is introduced, with the accuracy of the first order RC model improved. The results of verification on two set of real vehicle operation condition data show that compared with traditional algorithm, the algorithm proposed has significantly higher robustness with improved accuracy; the SOC estimation error can quickly converge to less than 2% and 3% at 25 and -20 ℃, respectively. Meanwhile, the results of sensitivity analysis show that the algorithm also has good robustness to initial errors as well. References | Related Articles | Metrics

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Lithium Battery SOC Estimation Based on Internal Resistance Power Consumption Jin Bowen, Qiao Huimin, Pan Tianhong, Chen Shan 2020, 42 (8):  1008-1015.  doi: 10.19562/j.chinasae.qcgc.2020.08.003 Abstract ( 263 )   PDF (3204KB) ( 648 )   Save Aiming at the problem of estimating the remaining capacity of lithium battery under different operation situations, a calculation method of remaining battery capacity based on internal resistance power discharge strategy and power integration is proposed. The first-order Thevenin equivalent circuit model of the battery is selected, the internal parameters of the battery are determined by discharge experiments, and the variable parameter model of the battery is established. According to the different operation requirements of the battery, the battery discharge current is controlled by power, to stabilize battery capacity and improve the robustness of the ampere-hour integral algorithm under stable discharge conditions. The temperature, high frequency fluctuation current and SOH of the battery are introduced into integral item to measure the capacity consumption rate of the battery, and the remaining capacity of the battery is estimated by power integration algorithm. The integration algorithm is combined with EKF to weaken the influence of integral error on estimation accuracy. The experimental bench is set up and the discharge condition of the lithium battery is designed with the corresponding discharge strategy and calculation method adopted. The results show that the method proposed can effectively enhance the estimation accuracy of battery remaining capacity. References | Related Articles | Metrics

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Stable Tracking Control of Autonomous Vehicles at Extreme Conditions Chen Long, Xie Yunpeng, Cai Yingfeng, Sun Xiaoqiang, Teng Chenglong, Zou Kai 2020, 42 (8):  1016-1026.  doi: 10.19562/j.chinasae.qcgc.2020.08.004 Abstract ( 515 )   PDF (2364KB) ( 589 )   Save Aiming at the difficulty in ensuring the accuracy and stability of tracking control of autonomous vehicles under extreme conditions, a comprehensive coordinated control scheme for longitudinal and lateral stability is proposed. Firstly the speed of autonomous vehicle under friction limit is planned and the speed tracking under the limit speed is achieved by means of longitudinal acceleration feedforward and state feedback controller. Then a lateral path tracking controller is designed by combining preview feedforward with artificial potential field feedback, and a stability control strategy is proposed based on the deviation of actual yaw rate from desired one, and the driving torque of longitudinal control is optimized. The results of Simulink/Carsim co-simulation show that the proposed comprehensive control scheme for longitudinal and lateral stability can improve the transient response of autonomous vehicles under extreme conditions, restrain the overshoot at the sudden change of road curvature, reduce the steady-state error in path following, and enhance the trajectory tracking accuracy and the lateral stability in the course of curve movement of autonomous vehicles. References | Related Articles | Metrics

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Driver Distraction Behavior Detection with Multi-information Fusion Based on Graph Convolution Networks Bai Zhonghao, Wang Yunyu, Zhang Linwei 2020, 42 (8):  1027-1033.  doi: 10.19562/j.chinasae.qcgc.2020.08.005 Abstract ( 249 )   PDF (3835KB) ( 659 )   Save In order to reduce the traffic accidents caused by driver's distraction, and detect the distraction state of the driver during automatic driving for judging whether the driver has the ability to take over the vehicle, a multi-information fusion driver distraction behavior detection method based on graph convolution is proposed. By analyzing the distraction behavior and posture features of the driver, the posture estimation graph of the driver is designed. The feature extraction of driver's posture estimation graph is conducted based on graph convolution network, the features extracted are classified by using full connected layer, and the driver's distraction behaviors are judged again by the fusion of key objects like mobile phone. Experiment results show that the method proposed can achieve 90% and 93% accuracy on SrateFarm dataset and the self-made dataset respectively with a detection speed of 20 frames per second, meeting the detection requirements of accuracy and real-time performance. References | Related Articles | Metrics

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Geometric Ranging of Unmanned Vehicle Driving Environment Image Dai Jinkun, Luo Yutao, Liang Weiqiang 2020, 42 (8):  1034-1039.  doi: 10.19562/j.chinasae.qcgc.2020.08.006 Abstract ( 253 )   PDF (3838KB) ( 353 )   Save A geometric ranging method for the image of the driving environment of the unmanned vehicle is proposed. Firstly, the migration-learning method is used to improve the Tiny-YOLOv2 network model so as to train and detect the object to be identified, mark the object and locate the position of the object in the image. Secondly, a method of object classification, edge detection and edge fitting is proposed to further extract image information of the object. Finally, a ranging model based on spatial geometry theory is established, and the distance measurement of the object is realized by combining the prior information of the object size. With this method, more than 88% of the measurement error within 4 m is less than 0.2 m, and the measurement error does not change much with the increase of distance. References | Related Articles | Metrics

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Optimal Control Strategy Design for Vehicle High-speed Emergency Lane Change Collision Avoidance Based on Radau Pseudospectral Method Zhang Jiaxu, Shi Zhengtang, Zhao Jian, Zhu Bing 2020, 42 (8):  1040-1049.  doi: 10.19562/j.chinasae.qcgc.2020.08.007 Abstract ( 517 )   PDF (3035KB) ( 323 )   Save An optimal control strategy for vehicle high-speed emergency lane change collision avoidance is proposed based on Radau pseudospectral method for solving the problem of trajectory planning and tracking control for vehicle high-speed emergency lane change collision avoidance. Firstly, the problem of trajectory planning and tracking control for vehicle high-speed emergency lane change collision avoidance is transformed into an optimal control problem of vehicle high-speed emergency lane change collision avoidance based on the combination of vehicle kinematics and kinetics model, which is then transformed again into a nonlinear programming problem by Radau pseudospectral method, and hence the optimum solution for the problem of trajectory planning and tracking control for vehicle high-speed emergency lane changing collision avoidance can be directly obtained: the desired longitudinal slip rates of tires and the desired steering angular speed of front wheels. Then, an adaptive sliding mode tracking control law of wheel slip rate, which has strong robustness for parameter perturbation and external interference, is devised based on discrete sliding mode variable structure control theory to achieve the tracking control of the desired longitudinal slip rates of tires. Finally, a model-in-the loop simulation system is built based on high-accuracy vehicle dynamics software to verify the feasibility and effectiveness of the control strategy proposed. References | Related Articles | Metrics

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Research on Chest Response of Elderly Drivers in Frontal Crash Wu Hequan, Peng Jinping, Deng Xiaoshun, Jin Xin, Hu Lin 2020, 42 (8):  1050-1059.  doi: 10.19562/j.chinasae.qcgc.2020.08.008 Abstract ( 341 )   PDF (9606KB) ( 297 )   Save In order to study the chest response of the elderly driver in vehicle frontal crash, firstly, a finite element model CHARM_70 for elderly female chest is built and its simulation results are compared with that of corpse experiment to verify the effectiveness of the model. Then with a round disk and a transversely installed round bar as two impactor heads and three impact heights and different impact speeds and impact masses chosen, 5 conditions of pendulum impact experiment are conducted on two elderly corpses PMHS1 and PMHS2. Meanwhile using model CHARM_70 with same setting as corpse experiments, similar 5 conditions of pendulum impact simulation are also carried out. Finally, the results of experiment and simulation, i.e. the relationships between impact force and chest compression, the maximum chest compression Cmax and the maximum chest viscosity response coefficient VCmax in five conditions are compared and analyzed. The results show that the chest response to round disk impacting middle position is larger than that to round bar impacting the same position, for model CHARM_70, the difference is 3 percentage points in Cmax and is 38% in VCmax. And for round bar impact, the impact height has relatively significant effects on chest response, the average chest response to round bar impacting high position is about 20% smaller than middle position impact, while the average chest response to round bar impacting low position is some 10% larger than middle position impact. References | Related Articles | Metrics

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Study on the Motion Posture Change and Crash Injury of Driver Under Autonomous Emergency Braking Cui Dong, Qi Zhinan, Zhang Hui 2020, 42 (8):  1060-1065.  doi: 10.19562/j.chinasae.qcgc.2020.08.009 Abstract ( 231 )   PDF (5350KB) ( 265 )   Save In order to study the influence of autonomous emergence braking (AEB) involvement on the passive safety of vehicle, through volunteer's real car tests, with the help of driving robot and on-board high-resolution cameras, 24 groups of driver's posture motion data are collected under different braking deceleration and speed, with the changing rule of driver's forward displacement in the process of AEB analyzed in this paper. The results show that at the same initial braking speed, the forward displacement of driver increases with the rise of braking deceleration. Under smaller braking deceleration, the initial braking speed has little effects on the forward displacement of driver, while under larger braking deceleration, the forward displacement of driver exhibits an apparent fluctuation with the rise in initial braking speed, showing no obvious rule. Through a simulation on THUMS human model, the injuries of driver with and without AEB involvement in frontal crash condition are comparatively analyzed, with a conclusion drawn that under existing passive safety development strategy, the involvement of AEB may aggravate driver's injury. References | Related Articles | Metrics

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Research on Wheel Hinge Failure in 25% Small Overlap Frontal Crash Zhang Jian, Zhao Qingjiang, Xu Zuowen, Shi Aimin, Guo Yihui 2020, 42 (8):  1066-1073.  doi: 10.19562/j.chinasae.qcgc.2020.08.010 Abstract ( 250 )   PDF (5734KB) ( 419 )   Save In the safety performance development concerning vehicle's small overlap frontal crash, wheels are the main load-bearing components, and the failure of wheel hinges will affect the force and deformation mode of the wheel, hence, accurately predicting the failure is an important difficult point in the early development of crash safety performance. Accordingly, a tensile test is proposed in this paper to obtain the failure force of hinge connecting wheel and chassis for accurately finding the solution of hinge failure. Firstly, a public simulation model is used to investigate the effects of wheel falloff from the vehicle on the result of crash. By combining simulation with numerical calculation, the correlation between the peak force in each direction of wheel hinge and the collision energy is analyzed to determine the measurement range of hinge failure force. Then a tensile test device is designed for a vehicle model adopting the same type of front suspension as the public model, with tests conducted and the failure forces of wheel hinges are obtained and then applied to the forward development of that production vehicle. The results show that the accurate simulation model with consideration of the failure force of wheel hinge can greatly enhance the simulation accuracy of small overlap frontal crash, thereby ensuring the forward safety performance development of the vehicle. References | Related Articles | Metrics

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Optimization Design of Low Drag Torque Parameters of High-Speed Multi-Plate Wet Clutch Zhang Lin, Wei Chao, Hu Jibin 2020, 42 (8):  1074-1081.  doi: 10.19562/j.chinasae.qcgc.2020.08.011 Abstract ( 161 )   PDF (1292KB) ( 501 )   Save It is found in experiments that the rub-impact between the friction plate and steel plate is easy to appear in the separation state of the high speed wet clutch, which results in sharp increase of drag torque of the clutch and affects the efficiency and reliability of transmissions negatively. Therefore, in this paper, taking the multi-plate wet clutch as the research object , an optimization design model of groove structure parameters and working parameters of the wet clutch is established, in which the minimum drag torque at the highest working speed is set as the optimization goal. The optimal design method based on the approximate model of drag torque is adopted. The structural parameters of the friction plate oil grooves and the working parameters of the wet clutch are optimized by using the optimized Latin hypercube experimental design method, the elliptical basis neural network model and the multi-island genetic algorithm. The optimization results are verified by simulation and experiments. The results show that the depth and the number of oil grooves among the structure parameters of the friction plate have obvious negative effects on drag torque; the clearance of friction pair in the working parameters of the clutch has a significant negative effect on drag torque. References | Related Articles | Metrics

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Optimization of Front Suspension and Steering System Based on Grey Correlation TOPSIS Method Zhang Zhifei, Xue Haoxiang, Chen Zhao, Pu Hongjie, Xu Zhongming, He Yansong 2020, 42 (8):  1082-1089.  doi: 10.19562/j.chinasae.qcgc.2020.08.012 Abstract ( 163 )   PDF (1804KB) ( 290 )   Save In order to reduce tire wear and improve braking nose dive performance, a selection strategy of multiple design variables is proposed based on the grey correlation TOPSIS method. The simulation model of front suspension and steering system is established by using multi-body dynamics simulation software and its K&C characteristics are analyzed, with its accuracy verified by experiments. With the target of improvement of tire wear and braking nose dive performance, based on the sensitivity analysis of 15 hard point coordinates of the front suspension and steering system, the weight of each index is determined by entropy weight method and subjective weight method, and 6 hard point coordinates with high comprehensive contribution coefficient are selected as design variables by combining the grey correlation degree and TOPSIS method, so as to construct the optimization design model. By using Isight software and NSGA-II algorithm, the Pareto optimal solution set is obtained and the optimal scheme of hard point arrangement of the suspension and steering system is finally determined. After optimization, the performance is improved significantly compared with the initial design, with the change rate of toe angle, camber angle, lateral and longitudinal displacement with wheel slip reduced by 48.9%, 21.2%, 26.6% and 20.5% respectively, the Ackerman percentage increased by 19.02%, the anti-dive rate increased from 9.2% to 30.4%, and the height of roll center reduced from 136 to 100.5 mm, effectively reducing tire wear and improving braking nose dive performance while ensuring operation stability. References | Related Articles | Metrics

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Review on Design Optimization Research of Hydraulic Torque Converter for Passenger Vehicles Wu Guangqiang, Chen Jie 2020, 42 (8):  1090-1096.  doi: 10.19562/j.chinasae.qcgc.2020.08.013 Abstract ( 179 )   PDF (1983KB) ( 410 )   Save The research progress and status quo of each stage in the optimization design process for hydraulic torque converter (HTC) are reviewed. Four aspects of researches on HTC including design and parameterization methods, the effects of design parameters on performances, performance prediction models, and design optimization methods are expounded, and the applications of the new technology in HTC are briefed. The research results of each stage are summarized. Finally the further research directions on HTC are look ahead. References | Related Articles | Metrics

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Two Descriptions of International Roughness Index of Road and Their Application Zhang Zhenwei, Chen Tao, Wang Wenzhu, Zhao Qi, Li Jie 2020, 42 (8):  1097-1102.  doi: 10.19562/j.chinasae.qcgc.2020.08.014 Abstract ( 337 )   PDF (1176KB) ( 355 )   Save In order to understand and apply international roughness index of road, the time domain description and time frequency domain description of international roughness index of road are studied. Based on the standard vehicle model of international roughness index of road, the time domain description of the international roughness index of road and the differential equations of motion for the vehicle model are established. In space frequency domain, the power spectral density representation of road roughness is established; in time frequency domain, the power spectral density representation of road excitation is established. Frequency response expression of suspension dynamic deflection velocity is derived from the standard vehicle model, and the time frequency domain expression of international roughness index of road is built. It is proved by analysis that the international roughness index of road is equivalent to power density of road excitation. Using the measured road roughness data of LTPP project in the United States, the international roughness index of road in time domain and time frequency domain are obtained. By comparison of the two, the correctness and validity of the description of the time frequency domain of the international roughness index of road are proved. The international roughness index of road in time frequency domain can be better determined by introducing median filter into the measured road roughness data. References | Related Articles | Metrics

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Direct Simulation and Optimization of the Aerodynamic Noise in a Car HVAC System Based on Lattice-Boltzmann Method Zhang Jia, Wu Haibo, Chen Qian, Fang Zhiyun, Wang Yigang, Yu Liuping 2020, 42 (8):  1103-1109.  doi: 10.19562/j.chinasae.qcgc.2020.08.015 Abstract ( 230 )   PDF (2736KB) ( 398 )   Save Aiming at the problem of loud noise in the HVAC system of a car, the lattice-Boltzmann method is adopted to directly simulate the noise and solve out the flow field and sound field, and by combining with tests the noise and structure optimization are conducted. The results show that the method adopted can accurately calculate the flow field and noise in air conditioning system, the sound pressure level curve simulated is basically similar to that by test, with only 0.8 dB(A) difference in overall sound pressure level. After optimization, the noise at ear positions reduce by 2 dB(A) at most. The study also reveals that quadrupole noise has big contribution in some frequency ranges, and using the lattice-Boltzmann method to simulate flow field and sound field is an accurate and effective way to calculate the aerodynamic noise of the duct system of HVAC. References | Related Articles | Metrics

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Research on Regulation Adaptation for Acoustic Vehicle Alerting System in Electric Vehicles Cao Yuntao, Tang Lechao, Liu Yingjie 2020, 42 (8):  1110-1116.  doi: 10.19562/j.chinasae.qcgc.2020.08.016 Abstract ( 233 )   PDF (3960KB) ( 548 )   Save In this paper, the tuning method and process of acoustic vehicle alerting system (AVAS) specified in national standard for electric vehicle running at low speed are expounded with the effects of the frequency spectrum energy distribution in AVAS on the lowest limit of exterior noise and interior sound quality emphatically discussed, and a sound quality evaluation method for AVAS is proposed. The results of test and evaluation show that by improving the frequency spectrum distribution of AVAS in the process of speed variation, the balance between the lowest noise limit specified in regulation and internal sound quality is achieved, enabling more all-roundly investigation into the effects of AVAS on the NVH performance of vehicle. References | Related Articles | Metrics

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Methodology Research on Optimization Design of Vehicle Interior Space Under Constraint of Body Performance Wu Jingwei, Zhang Guangya, Lü Juncheng, Li Qian 2020, 42 (8):  1117-1123.  doi: 10.19562/j.chinasae.qcgc.2020.08.017 Abstract ( 182 )   PDF (2354KB) ( 377 )   Save Traditional vehicle body design usually only considers the optimization of body performance, but seldom considers the optimization design of vehicle interior space. In this paper, the evaluation indexes of vehicle interior space are improved. A new design method and development process of optimization of vehicle interior space under constraint of body performance is put forward. A fusion model of body performance analysis and vehicle interior space is established. The optimization design is carried out, with the maximization of vehicle interior space and the minimization of the body mass as the target. Taking an SUV model as an example, the overall volume of vehicle interior space and the luggage capacity increase by more than 6% compared with the original design with the body structural performance satisfied, and the vertical head space increase by more than 7%. Other interior space indexes are also improved to a certain extent. Finally, the effectiveness of the proposed method is verified by the vehicle test. References | Related Articles | Metrics

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Analysis and Optimization on Co-curing Molding of CFRP-steel Composite with Super-hybrid Structures Jing Min, Gong Youkun, Wang Zhiwen, Liu Yongjie, Li Na, Song Zengrui, Ning Huiming, Hu Ning 2020, 42 (8):  1124-1130.  doi: 10.19562/j.chinasae.qcgc.2020.08.018 Abstract ( 174 )   PDF (4321KB) ( 362 )   Save The lightweight design of the B-pillar in an electric vehicle with carbon fiber reinforced polymer (CFRP)-steel super-hybrid structure is carried out. The discrepancy in properties of different material inevitably leads to the occurrence of residual stress and solidification deformation in molding process, affecting the mechanical performance and dimensional accuracy of the components. Accordingly, the process of hot-press molding with co-curing of a U-shaped super-hybrid structure of CFRP-steel composite is analyzed by finite element method, in which the CHILE prediction model is adopted for composite curing process. On the premise of ensuring the molding efficiency, an optimization on curing process parameters is conducted. The results show that with optimized curing process parameters,the residual stress and curing deformation of the co-curing molded U-shaped super-hybrid structure of CFRP-steel composite can be effectively reduced. References | Related Articles | Metrics

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Research Progress in Manufacturing Process of Composite Leaf Spring Ke Jun, Wu Zhenyu, Shi Wenku, Hu Xudong 2020, 42 (8):  1131-1138.  doi: 10.19562/j.chinasae.qcgc.2020.08.019 Abstract ( 263 )   PDF (2588KB) ( 505 )   Save Composite leaf spring is a research hotspot in the field of vehicle lightweighting due to its much better comprehensive performance than steel counterpart. However, the manufacturing process of composite leaf spring is far from mature, leading to high trial production cost and poor product performance stability, which seriously restricts the popularization and application of composite leaf spring. This paper presents an overview of research progress on the manufacturing process of composite leaf spring, including the research results of compression molding, pultrusion, filament winding and resin transfer molding processes. Finally, the development trends and bottleneck problems of manufacturing process of composite leaf spring are summarized. References | Related Articles | Metrics

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Diesel Engine Fault Diagnosis Method Based on VMD and Multi-Scale Dispersion Entropy Qiao Xinyong, Gu Cheng, Han Lijun 2020, 42 (8):  1139-1144.  doi: 10.19562/j.chinasae.qcgc.2020.08.020 Abstract ( 178 )   PDF (2658KB) ( 315 )   Save In order to extract the diesel engine fault characteristics from the non-stationary and nonlinear cylinder head vibration signal, a fault diagnosis method for diesel engine misfire based on VMD and multi-scale dispersion entropy is proposed. The vibration signal of diesel cylinder head is decomposed by VMD, and then the modal component with the minimum dispersion entropy is selected as the analysis signal to calculate the multi-scale dispersion entropy (MDE). The first six scales of dispersion entropy as fault eigenvector are input into the support vector machine of particle swarm optimization (PSO-SVM ) for misfire fault classification and judgment, which is compared with other four common methods. The results show that the proposed diagnostic method can effectively extract fault features and accurately identify fault types, which is better than the methods compared. References | Related Articles | Metrics