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Published by AUTO FAN Magazine Co. Ltd.

Table of Content

    25 June 2024, Volume 46 Issue 6 Previous Issue   
    Vehicle Trajectory Tracking and Collision Avoidance Control Based on Multi-style Reinforcement Learning
    Liming Xiao,Fawang Zhang,Liangfa Chen,Haoqi Yan,Fei Ma,Shengbo Eben Li,Jingliang Duan
    2024, 46 (6):  945-955.  doi: 10.19562/j.chinasae.qcgc.2024.06.001
    Abstract ( 433 )   HTML ( 43 )   PDF (4181KB) ( 553 )   Save

    Trajectory tracking and collision avoidance are key functions of vehicle intelligence. For the singular control style limitation of existing control methods in the same scene, a novel multi-style reinforcement learning (RL) method is proposed in this paper. To achieve diversity in control styles, style indicators are innovatively incorporated into value and policy networks to establish a multi-style tracking and collision avoidance policy network. Alongside this, a multi-style policy iteration framework is developed combining the distributional RL theory. Based on the framework, a multi-style distributional soft actor-critic algorithm (M-DSAC) is put forward. Through simulation and real vehicle tests, it is validated that the proposed method is capable of executing trajectory tracking and collision avoidance tasks across various driving styles, such as aggressive, neutral, and conservative, with the real vehicle’s steady-state trajectory tracking error less than 5 cm, with high control accuracy. The average single-step decision-making time for the real vehicle is merely 6.07 ms, meeting real-time requirements.

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    A Multi-class Multi-target Tracking Algorithm Combining Motion Speed and Appearance Features in Driving Scenarios
    Hai Wang,Yuxuan Ding,Tong Luo,Meng Qiu,Yingfeng Cai,Long Chen
    2024, 46 (6):  956-964.  doi: 10.19562/j.chinasae.qcgc.2024.06.002
    Abstract ( 218 )   HTML ( 13 )   PDF (4411KB) ( 800 )   Save

    Multi-target tracking algorithms based on camera sensors are crucial to autonomous driving. In driving scenarios, traditional association schemes based on Intersection over Union(IoU) of front and back frames are subject to a great deal of ID switches, which is more pronounced in the case of opposing traffic and self-turning vehicles. In this paper, the target's motion speed in the 2D plane is taken as a variable to extend the matching space to design IoU based on the target's speed change: the Velocity IoU, so as to optimize the front and back frame target association method. Meanwhile, a self-supervised appearance model is used to extract the appearance features of different targets. Based on the above motion model as well as the appearance model, a complementary association strategy is proposed, which ultimately achieves multi-category multi-target tracking in driving scenarios. The method is validated on BDD100K, with corresponding mMOTA of 45.2, mIDF1 of 55.2, and IDs of 8 793, which outperforms most tracking algorithms.

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    Research on Intelligent Vehicle Trajectory Planning Based on Multimodal Trajectory Prediction
    Jing Huang,Xiangzhen Liu,Xiaoyang Deng,Ran Chen
    2024, 46 (6):  965-974.  doi: 10.19562/j.chinasae.qcgc.2024.06.003
    Abstract ( 496 )   HTML ( 30 )   PDF (4225KB) ( 545 )   Save

    Due to the uncertainty of the driver's intention under the mixed traffic flow, the driving trajectory will present multimodal attributes. In order to improve safety and realize personalized driving, a trajectory planning algorithm for intelligent vehicle based on the multimodal trajectory prediction of environmental vehicles is proposed in this paper. Firstly, a trajectory prediction model is established by combining graph convolutional neural network (GCN) and long short-term memory network (LSTM) with attention mechanism to predict the probability distribution of future trajectories under different types of driving intention. Then, for the set of predicted trajectories under multi-intention probabilities of environmental vehicles, a certain probability threshold is set to select sure trajectories according to the automatic driving style preference, which is projected onto the planning path to generate the S-T diagram, and speed planning based on collision risk avoidance is carried out through dynamic planning and quadratic planning. Finally, based on the model predictive control (MPC), the model proposed in this paper is simulated and tested in typical lane changing scenarios and real-road scenarios of NGSIM and compared with the existing model for validation. The results show that the model proposed in this paper is better than the model in comparison in terms of safety, comfort, and driving efficiency, which can realize the optimal trajectory planning under the premise of accurately predicting future trajectories of the environmental vehicles to ensure safe and efficient driving of autonomous vehicles.

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    Risk Avoidance Decision Planning for Intelligent Driving Vehicles Based on Spatiotemporal Risk
    Chao Yang,Fan Yang,Weida Wang,Tianqi Qie,Yansong Wang,Hongwei Wang
    2024, 46 (6):  975-984.  doi: 10.19562/j.chinasae.qcgc.2024.06.004
    Abstract ( 359 )   HTML ( 24 )   PDF (5100KB) ( 482 )   Save

    In order to improve the collision risk assessment method of intelligent driving vehicles in complex road scenarios to generate effective risk avoidance trajectories in real time, in this paper a risk avoidance decision planning method for intelligent driving vehicles based on spatiotemporal risk is proposed. Firstly, the multi-domain risk measurement of time-space coupling is used as the evaluation index to supervise the horizontal and longitudinal collision risk of intelligent driving vehicles. At the same time, the change of driving risk index is monitored in real time. Through the correlation analysis with the risk database of typical risk avoidance scenarios, potential collision risk is judged, so as to avoid the risk in advance. Then, according to the driving risk field, the uneven sampling of the vehicle target state is carried out to avoid the driving area with high driving risk and improve the safety and real-time performance of the risk avoidance planning. The experimental results show that the proposed risk avoidance decision planning method can safely and effectively avoid the risk of horizontal and longitudinal collision, which can detect the potential collision risk 0.5 s in advance according to the time domain correlation analysis of the risk index, so as to avoid the risk smoothly in advance. The average planning time of the risk avoidance trajectory can be shortened from 0.13 to 0.07 s by uneven sampling.

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    Research on Collision Avoidance Limit of Autonomous Vehicles
    Guodong Wang,Li Liu,Yu Meng,Haiping Du,Guoxing Bai,Qing Gu
    2024, 46 (6):  985-994.  doi: 10.19562/j.chinasae.qcgc.2024.06.005
    Abstract ( 225 )   HTML ( 12 )   PDF (3016KB) ( 403 )   Save

    The precise computation of the limit collision avoidance (CA) distance for various collision avoidance control strategies is the basis for collision avoidance decision-making and control of autonomous vehicles. To clarify the impact of differential braking control on CA distance, explore the limit collision avoidance capability of steering and differential braking integrated control, and improve the calculation accuracy of the limit CA distance, in this study, a method for calculating the limit CA distance of autonomous vehicles based on nonlinear integrated vehicle dynamics and optimal control theory is proposed. Firstly, a nonlinear 7-degree-of-freedom integrated vehicle dynamics model and a Pacejka tire model with combined slip conditions are established. Subsequently, based on the established models, a limit CA distance solution problem is constructed, which is then transformed into an optimal control problem. Next, the Gauss Pseudospectral Method (GPM) is designed to convert the optimal control problem into a nonlinear programming problem and solve it. Finally, the limit CA distances for steering control, braking control, steering and braking integrated control, and steering and differential braking integrated control are analyzed, and compared with the limit CA distances calculated based on the particle model and that tested by CarSim. The results show that the integrated control of steering and differential braking can further reduce the CA distance and significantly improve the collision avoidance capability of autonomous vehicles. The method proposed in this study can significantly improve the calculation accuracy of limit CA distance and the reliability of CA decision results.

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    Research on the Driver's Hazard Perception State Recognition Model Based on Strength and Weakness Perception Design
    Juan Zeng,Hao Wang,Bo Xu,Hongchang Zhang
    2024, 46 (6):  995-1005.  doi: 10.19562/j.chinasae.qcgc.2024.06.006
    Abstract ( 148 )   HTML ( 9 )   PDF (3748KB) ( 291 )   Save

    Driver hazard perception plays an important role in preventing and reducing road traffic accidents. For the disadvantages of inconsistent representation of feature vectors of hazard perception and insufficient interpretability of algorithms to practical problems, in this paper 3×2×2 experimental scenarios of three dimensions in terms of danger resource, overt and covert hazard scenes, strong and weak hazard perception state through artificial control to realize the predetermined classification of hazard perception. A combination of paired T-test and Wilcoxon signed-rank test is designed to quantitatively compare the difference of features in the state of strong and weak perception. A binary classification of hazard perception state based on 10-fold cross-parameter tuning SVM algorithm is proposed. The results show that drivers are more active in reacting to danger in the state of strong hazard perception, tending to avoid danger rather than emergency avoidance, while maintaining a lower speed, preferring throttle control rather than brake control, with increase of gaze and saccade behaviors. In the scene of covert hazard source, the driver's manipulation is stronger and more frequent, and the level of HP affected by the overt and covert hazard is related to the type of hazard, with highest level by motorcycle and lowest by human. At C=1, γ=0.1, the SVM model has the best performance with the accuracy of 89.2%, the precision of 90.6%, the recall of 87.8%, and the F1 value of 0.888 when the time headway, standard deviation of vehicle speed, maximum brake pedal force, standard deviation of acceleration, pre-deceleration time, mean vehicle speed, standard deviation of throttle opening, number of saccades, number of fixations are selected as features. The model of XGBoost has lower recognition ability for weak perception than the model of SVM. This study has significant guiding significance for the quantitative evaluation of drivers' hazard perception state.

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    Research on Mass Estimation Algorithm of Intelligent and Connected Commercial Vehicle Based on Cloud Road Map
    Ao Zhang,Shuyan Li,Bolin Gao,Keke Wan,Guang Zhou,Tongyi Cao
    2024, 46 (6):  1006-1014.  doi: 10.19562/j.chinasae.qcgc.2024.06.007
    Abstract ( 162 )   HTML ( 8 )   PDF (3097KB) ( 358 )   Save

    Vehicle mass is a key state variable of vehicle dynamics parameters. In the driver assistance system, accurate estimation of the vehicle mass is important for the planning and control algorithms. Traditional mass estimation algorithms face challenges in estimating road slope and vehicle mass at the same time. In particular, the error of slope estimation may seriously affect the accuracy of mass estimation. Currently, the cloud control platform provides high-precision road map information, which provides a new idea for further optimizing the mass estimation algorithm. Based on the vehicle-cloud collaborative framework of the cloud control platform, the system architecture of commercial vehicle mass estimation under the cloud control system is designed in this paper. Then, based on the extended Kalman filter theory, combining with the road map information in the cloud, the commercial vehicle mass estimation algorithm is developed. The vehicle mass is estimated by taking the road slope as a known parameter rather than a variable state parameter, and the algorithm is compared and verified by the driving data collected by the real vehicle test. The experimental results show that the mass estimation algorithm based on cloud slope information can achieve fast convergence under no-load and full-load conditions, and the absolute percentage error of the estimated mass is within 3%. Compared with the traditional algorithm of simultaneous estimation of mass and slope, it can converge to the real mass of the vehicle faster and more accurately.

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    Semi Solid-State LiDAR Object Detection Algorithm Enhanced by Feature Stability Enhancement
    Lisheng Jin,Hongyu Zhang,Baicang Guo
    2024, 46 (6):  1015-1024.  doi: 10.19562/j.chinasae.qcgc.2024.06.008
    Abstract ( 149 )   HTML ( 9 )   PDF (5005KB) ( 284 )   Save

    Stable point cloud feature extraction is crucial for 3D object detection using LiDAR. For the limitation of existing deep learning algorithms that can only handle point clouds from mechanically rotating LiDAR but lack support for semi solid-state LiDAR data, in this paper a target detection model suitable for semi solid-state LiDAR based on IA-SSD is established. Firstly, Cloth Simulation Filtering (CSF) is added at the front end of point cloud encoding for ground suboptimal filtering. Secondly, an attention mechanism composed of local feature fusion and global bilinear regularization layers is utilized to promote the fusion of geometric information and feature information of point clouds from both local and global perspectives. Thirdly, GhostGConv is employed to replace the original inefficient point-by-point convolution, and enhanced feature interaction of point clouds is achieved through channel shuffling mechanism to construct an enhanced feature extraction network. Finally, the above modules are integrated into the point detector IA-SSD to complete model construction. The validation results conducted on the SimoSet semi solid-state lidar dataset show that the proposed method significantly outperforms other algorithms supported by the SimoSet dataset in terms of accuracy metrics. In the medium difficulty detection tasks on the KITTI dataset, the proposed method enhances the average detection accuracy of IA-SSD in the three categories by 1.17, 1.47, and 0.5 percentage points, respectively.

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    Analysis on Influence of Micropore Spacing and Size on Droplet Flow Transport Characteristics on Gas Diffusion Layer in PEMFC
    Binyan Yu,Jian Ma,Yisong Chen,Limin Geng,Qian Wang
    2024, 46 (6):  1025-1033.  doi: 10.19562/j.chinasae.qcgc.2024.06.009
    Abstract ( 104 )   HTML ( 4 )   PDF (2734KB) ( 349 )   Save

    Proton exchange membrane fuel cell (PEMFC) is considered as one of the most promising power devices for new energy vehicles, whose performance is affected by the droplet formation and dynamic transport properties on the surface of the gas diffusion layer (GDL). In this paper, based on the pseudo-potential model of the lattice-Boltzmann method (LBM), the dynamic processes of droplet emergence, growth, and shedding from the GDL surface are simulated, and the effect of micro pore spacing and micro pore size on the dynamic characteristics of droplets on the surface of the GDL as well as the pressure drop in the flow channel are analyzed in detail. The research results show that in the case of dual inlet holes, when the distance between two micropores is less than a certain value, the two droplets will merge. The merged droplet will increase the pressure drop in the airflow channel and shorten the time for droplet discharge. When the two micropore spacing is sufficiently large, there is almost no interaction between the two droplets, with the same droplet exclusion time, and the pressure drop inside the flow channel decreases with the increase of the micropore spacing. And the pressure drop in the flow channel decreases with the increase of micropore spacing. The motion of droplets with different micropore sizes on the surface of GDL is mainly affected by the gas-actuated shear force, and the motion period of droplets with upstream micropore size larger than downstream micropore size is shorter compared to the motion period of droplets with larger downstream micropore size.

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    Study on Lithium Battery Fast Charge Performance with Ripple Charging Current
    Tao Ye,Jianhua Wu,Linfeng Zheng,Yuxin Zhang,Chaofeng Hong
    2024, 46 (6):  1034-1044.  doi: 10.19562/j.chinasae.qcgc.2024.06.010
    Abstract ( 345 )   HTML ( 12 )   PDF (3848KB) ( 318 )   Save

    Sinusoidal ripple current (SRC) charging has some performance optimization for lithium-ion battery charging, but existing studies on SRC charging are based on DC ratios of 1C and below, with no significant optimization compared with DC charging. In order to meet the market demand for fast charging, the effect of 2C high rate SRC fast charging on the cycle life of lithium batteries is studied in this paper for the first time. The analysis of battery capacity, internal resistance, temperature rise and increment capacity (IC) after cycle life experiment with different AC frequencies and amplitude shows that although the temperature rise of the proposed SRC fast charging is higher than that of DC due to the increase of current RMS, the battery life performance is significantly better than that of DC. The optimal performance is achieved when the AC amplitude is 3C (AC/DC = 1.5) and the AC frequency is higher than the characteristic frequency (825 Hz). After 100 cycles at 10 kHz frequency, the battery capacity loss and loss of active material (LAM) is reduced by 70.37% and 59.6% compared with DC respectively. After 200 cycles, the internal resistance increment is only 1/3.51 of DC, with the capacity fading by only 51.17%, and the useful life 251% longer than DC.

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    Research on Participation of Electric Vehicles in Microgrid Load Power Fluctuation Mitigation Based on Digital Twin Hybrid Energy Storage
    Longfei Ma,Baoqun Zhang,Liyong Wang,Jiani Zeng,Ran Jiao,Cheng Gong
    2024, 46 (6):  1045-1053.  doi: 10.19562/j.chinasae.qcgc.2024.06.011
    Abstract ( 150 )   HTML ( 4 )   PDF (1265KB) ( 310 )   Save

    For the problem that the peak load of electric vehicles will increase significantly after they are connected to the microgrid, which will cause the peak-valley difference to increase, and thus affect the stable operation of the microgrid, a method for reducing load power fluctuation of electric vehicles participating in the microgrid based on digital twin hybrid energy storage is proposed. The load characteristics of electric vehicles are analyzed by calculating the initial charging state and off-grid time of electric vehicles. Combining the digital twin technology with the microgrid hybrid energy storage system, the digital twin hybrid energy storage model is constructed, and the load power fluctuation flattening objective function is constructed according to the load characteristics of electric vehicles, so as to realize the one-time control of load power fluctuation. The load power fluctuation of electric vehicles participating in microgrid is stabilized by HESSS self-regulation and secondary load power correction. The test results show that the load power fluctuation is between 20 and 60 kW under the application of the method, with the power supply shortage probability of the microgrid lower than 33%, and the peak-valley difference of the power load in typical and atypical day lower than 44%. It shows that this method can analyze the charging state of electric vehicles under different states, and can effectively realize the load power leveling of microgrid.

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    Research on the Design and Test Evaluation Methods of the Ejector for PEM Fuel Cell Vehicle
    Weidong Zhang,Sanqing Jiang,Wenjun Guo,Xiaocheng Ge,Fayue Hu,Yao Liu
    2024, 46 (6):  1054-1061.  doi: 10.19562/j.chinasae.qcgc.2024.06.012
    Abstract ( 138 )   HTML ( 2 )   PDF (2811KB) ( 191 )   Save

    During the research and development of fuel cell ejectors for vehicles, it is difficult to monitor the wet hydrogen flow rate, with difficulty in the bench technology and high test cost, as well as safety risk and energy waste problems. To address the problems, based on the derivation of the flow rate relationship between air and hydrogen, air and 100% RH hydrogen under the same working conditions, an ejector for the 110 kW fuel cell is developed and tested by air and hydrogen, and numerical simulation analysis is conducted. It is found that the mass fraction of water vapor in the fluid ejected by the ejector reaches 40% to 50%. Under the same working conditions, the volume and mass flow rate of air and hydrogen is equal to the square root of the gas constant ratio and the square root of the reciprocal ratio, respectively. The ratio of volume and mass flow rate of air and hydrogen is 3.786 and 0.264 1, respectively. The average relative error between the measured and simulated air flow rates for working, ejected, and mixed fluid mass flow rates is 4.48%, 4.54%, and 2.78%, respectively. After conversion, the measured air data is consistent with the hydrogen test data, with an average deviation rate of 5.4% and 6.11% from the simulated wet hydrogen data, respectively. The hydrogen test data is also consistent with the wet hydrogen simulation data after conversion. Therefore, the processed air test data can be used for studying the characteristics of fuel cell ejectors for vehicles.

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    Design and Performance Optimization of Electric Drive System Through-Wall On-Load EMC Test System
    Xiaoshan Wu,Xiaohui Shi,Xiaoxia Yu,Xu Li,Jin Jia
    2024, 46 (6):  1062-1074.  doi: 10.19562/j.chinasae.qcgc.2024.06.013
    Abstract ( 158 )   HTML ( 2 )   PDF (8939KB) ( 221 )   Save

    The on-board EMC test system is an important equipment for testing the EMI performance of electric drive system of new energy vehicles. To optimize self-developed on-load EMC test system in China and promote the research of EMI characteristics of electric drive system, this study self-developed the first on-load EMC test system for electric drive through wall that can fully meet the CISPR 25-2016 test standards. By analyzing the demand of EMC test, the design scheme of EMC test system is proposed. Then, a three-dimensional model of the EMC test system is established and electromagnetic simulation is carried out, while the interference sources and shielding integrity of the system are analyzed, so as to guarantee the EMC compatibility of the designed system. Finally, by building the EMC test system, the accuracy and reliability of the system are further improved after analysis and optimization based on the bottom noise test.

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    Platform Design of Vehicle Body Based on Multi-object Discrete Topology Optimization
    Junwei Hua,Wenbin Hou
    2024, 46 (6):  1075-1084.  doi: 10.19562/j.chinasae.qcgc.2024.06.014
    Abstract ( 127 )   HTML ( 2 )   PDF (4842KB) ( 348 )   Save

    Platform design for product families can increase component commonality and reduce production cost. However, current research on platform is primarily concentrated at the parametric design, lacking direct methods for platform design at the topology structure of product. Therefore, a parallel design method suitable for multi-objects topology structure for the platform design requirements of vehicle body structure is proposed in this paper. Firstly, the improved graph decomposition algorithm is combined with multi-objective genetic algorithm to obtain the optimal design solution for the topology structure partition of a single vehicle body. Then, a multi-population and multi-chromosome genetic algorithm (MPMCGA) for multi-object optimization is proposed based on the modular design process of vehicle body topology structure, which ensures that the design objective loss of each object is within an allowable range while enhancing the sharing potential of modules. Finally, platform design is applied to the underbody panel of three concept vehicle bodies, verifying the effectiveness of the multi-object discrete topology optimization method.

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    Research on Braking Performance of Automotive Rear Wing Designed by Adaptive Fuzzy Control Strategy
    Yizhe Chen,Yiqun Tang,Hui Wang,Bo Qin,Shiping Liang,Liu Yang
    2024, 46 (6):  1085-1095.  doi: 10.19562/j.chinasae.qcgc.2024.06.015
    Abstract ( 167 )   HTML ( 6 )   PDF (3842KB) ( 443 )   Save

    As a key component of the performance cars and sports cars, the rear wing has a great impact on the drivability and stability of the car. During the driving process of cars, the speed, due to constant change of the acceleration, and the steering angle, the traditional design method of the rear wing system can’t take into account the nonlinear relationship between the input and output of the control system and the input uncertainty. In this paper, a design method for the rear wing based on the fuzzy control strategy is proposed to deal with above-mentioned problems. The relationship between vehicle speed and brake pedal travel with rear wing angle of attack is studied. The executive structure of the adaptive rear wing system is designed and stability analysis is carried out. The braking performance of the vehicle with added rear rights is simulated ad verified. The results show that the rear wing position can be adaptively controlled during vehicle driving by using this control strategy. The designed mechanism ensures the large speed ratio required for the wing transmission process and keeps the wing in the target position. Using the new designed adaptive rear wing, the driving stability is good at low speed, while the braking performance of the car at high speed is improved by 4.7%, with the braking distance reduced from 38.2 m to 36.9 m, shortened by 3.3%. This study provides a method for vehicle rear wing design that adapts to vehicle status, which is a reference for the improvement of automotive rear wing technology and industrial applications.

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    Adaptive Pressure Control for Electronic Boost Brake System Considering Multi-dimensional Nonlinear Disturbances
    Bing Zhu,Yanpeng Tang,Dongbo Zhang,Jian Zhao,Zhicheng Chen
    2024, 46 (6):  1096-1103.  doi: 10.19562/j.chinasae.qcgc.2024.06.016
    Abstract ( 178 )   HTML ( 11 )   PDF (3197KB) ( 395 )   Save

    In order to solve the multi-dimensional nonlinear disturbances of the electronic boost brake system in terms of mechanics, electronics and hydraulics, in this paper an adaptive pressure control strategy is proposed. The outer hydraulic controller incorporates adaptive radial basis function neural networks and robust sliding mode theory to overcome hydraulic time-varying uncertainties. The intermediate layer controller adopts Karnopp friction feedforward compensation and sliding mode control to deal with the nonlinear friction hindrance of the transmission mechanism. The inner layer current controller solves the problem of electromagnetic coupling of the motor using Lyapunov theory. Simulation and hardware-in-the-loop test results show that the designed pressure control strategy can maintain the steady-state pressure tracking error of the EBBS active braking within 0.15 MPa under various operating conditions.

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    Research on the Performance Optimization of DCT Four-Stage Downshift Based on STB
    Jun Gong,Lei Wang,Zhijie Xing,Jianjun Zhu
    2024, 46 (6):  1104-1113.  doi: 10.19562/j.chinasae.qcgc.2024.06.017
    Abstract ( 98 )   HTML ( 4 )   PDF (4808KB) ( 196 )   Save

    The shift of DCT is composed of two parts, the pre-engagement control of the fork and the shift control of the clutch. In the process of power downshift, the engagement time of the fork is very long, and the corresponding clutch torque must be reduced to zero before the pre-engagement control can be executed. Under some working conditions, the delay of the whole gear shift process will be caused by waiting for the pre-engagement shift, affecting the acceleration response of the whole vehicle, which is especially obvious in the coaxial power downshift process. In order to optimize the four-stage downshift performance of a DCT model, the STB based shift is proposed to optimize the shift time and improve the power response of vehicles. STB is a semi power interruption shift method applied to DCT. The advantages and disadvantages of STB is elaborated in this paper by making a detailed comparison of the whole shift process with the normal shifting. In order to compensate for the temporary power interruption caused by STB shifting, a complete control strategy is designed. On the one hand, a targeted kick down logic is developed, and the corresponding shift scheduling is adopted to control the timing of multi-stage downshift, so that the fourth-stage downshift is only triggered when kick down occurs. On the other hand, an open-loop algorithm is used to convert the engine speed control into time control during the shifting process, so as to achieve the effect that the engine speed is just synchronized when the pre-engagement shift is done. After comparison and verification on actual vehicles, the STB shifting greatly shortens the shift time of the four-stage downshift, and the power response of the whole vehicle is significantly optimized.

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    Decision System Design of Personalized Thermal Comfortable Intelligent Air Conditioning for Automobile Passenger Cabin
    Yang Luo,Ping Liu,Mingjie Liu,Changhao Piao,Peng Yuan,Kailin Wan
    2024, 46 (6):  1114-1124.  doi: 10.19562/j.chinasae.qcgc.2024.06.018
    Abstract ( 282 )   HTML ( 16 )   PDF (2780KB) ( 250 )   Save

    In order to further improve the intelligence and comfort level of the air conditioning system of the automobile passenger cabins, a personalized intelligent air conditioning decision system design based on the thermal comfort theory is proposed in this paper. Firstly, the thermal comfort calculation method based on the predicted mean vote (PMV) and predicted percentage of dissatisfaction (PPD) theories is improved for the automobile passenger cabin. Furthermore, the thermal comfort features of passengers in the passenger cabin are extracted by using human portrait technology, and the theoretical calculation-based thermal comfort data set of the passenger cabin is constructed on the basis of experts' experience knowledge. Then, machine-learning algorithm is used to build the random forest decision-making model of personalized thermal comfort air conditioning system, so as to meet the intelligent decision-making requirements of personalized thermal comfort. Finally, the complete system framework and design are given. The test results show that the decision-making accuracy of the proposed system model is above 90%, and the results of real vehicle testing show that the proposed system can identify the characteristics of drivers and passengers to recommend personalized thermal comfort parameters in real time, which verifies the effectiveness and practical value of the decision-making method in this study.

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    Performance Study of Cooling System for a High-Power Heavy Truck Based on 1D/3D Coupled Simulation
    Haojie Cheng,Yanda Ma,Yakun Xu,Yanxun Wu,Liping Dong,Zhenhua Yu,Yilun Zhang
    2024, 46 (6):  1125-1136.  doi: 10.19562/j.chinasae.qcgc.2024.06.019
    Abstract ( 140 )   HTML ( 8 )   PDF (7779KB) ( 206 )   Save

    With the rapid development of the economy, the demand for high power commercial vehicle is growing. Higher engine power means higher heat dissipation, which causes bigger challenges to the matching of engine cooling system and the spatial layout of engine compartment. For a heavy commercial vehicle equipped with 600 horsepower engine, the vehicle thermal flow field and 1D model of engine cooling system are developed based on 1D/3D coupled simulation to investigate the effects of fan cover and deflector on the intake air flow rate and average air temperature of the radiator. Meanwhile, according to the engine thermal balance test data, the matching calculation of engine cooling system is completed and the vehicle thermal balance test verification is conducted. The results show that compared with a single-layer fan shield, the C-type fan shield generates lower turbulent kinetic energy, which can provide more airflow. When the speed ratio of the water pump drops from 2.2 to 1.8, the outlet temperature at the maximum torque point and power point is 99.2 and 96.2 ℃ respectively, which can meet the cooling demand and also reduce the energy consumption of water pump. In addition, the vehicle environment cabin test also verifies the accuracy of the simulation model and the C-type air shield can effectively reduce the water temperature of the cooling system under high torque conditions.

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