Table of Content

25 May 2020, Volume 42 Issue 5 Previous Issue    Next Issue

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Study on the States of Autonomous Vehicle Based on Gaussian Pseudospectral Method Tang Xiaofeng, Yang Lin, Yuan Jingni 2020, 42 (5):  567-573.  doi: 10.19562/j.chinasae.qcgc.2020.05.001 Abstract ( 876 )   PDF (1461KB) ( 756 )   Save Aiming at the problem of multi-stages multi constraints trajectory optimization of autonomous vehicle, based on Gaussian pseudospectral method, scenario-based environment model and vehicle dynamics model are established and a variety of state constraints covering vehicle dynamics constraints and speed constraint are defined, including the parameter constraint conditions of initial and final states in each stage of autonomous driving. Then Gaussian pseudospectral method is adopted to get the approximate expression by the discretization of control variables and state variables, hence the trajectory planning problem is transformed into the optimization problem of performance indicators and finally a safe and effective path trajectory of autonomous vehicle is obtained. The results of research show that Gaussian pseudospectral method has the features of high computation accuracy and fast solving speed, and can achieve multi-stages trajectory optimization with consideration of various constraint conditions References | Related Articles | Metrics

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Motion Planning of High Speed Intelligent Vehicle Based on Front Vehicle Trajectory Prediction Zhang Yiming, Zhou Bing, Wu Xiaojian, Cui Qingjia, Chai Tian 2020, 42 (5):  574-580.  doi: 10.19562/j.chinasae.qcgc.2020.05.002 Abstract ( 768 )   PDF (2964KB) ( 701 )   Save In view of the fact that most of the existing motion planning algorithms only consider the current state of the obstacle vehicle, a high-speed vehicle motion planning algorithm based on trajectory prediction of the front vehicle is proposed. Firstly, the front vehicle trajectory is predicted by combining the driving intention and the vehicle motion model. Then, the Bezier curve is used to plan the main vehicle trajectory. By combining the risk probability of collision with the front vehicle in the process of collision avoidance, the characteristics of vehicle speed variation and vehicle motion stability in high-speed collision avoidance, the objective function is established. Taking into consideration of the vehicle dynamics and kinematics constraints, the sequential quadratic programming (SQP) is used to optimize the position of the control point of Bezier curve and the moving target point of the main vehicle, and the optimal collision avoidance trajectory is obtained. Finally, the main vehicle collision avoidance trajectory is planned under the two working conditions of straight ahead and lane changing of the front vehicle and the movement state change and the collision risk probability change of the main vehicle in the process of collision avoidance are analyzed under different working conditions. The results show that the proposed motion planning algorithm can ensure vehicle collision avoidance safety and motion stability References | Related Articles | Metrics

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Active Obstacle Avoidance Algorithm Based on Lateral Safety Distance Model Hu Zhaohui, Huang Shunxia, Du Zhanpeng, Guo Xing, Gao Hexuan 2020, 42 (5):  581-587.  doi: 10.19562/j.chinasae.qcgc.2020.05.003 Abstract ( 503 )   PDF (1695KB) ( 534 )   Save The existing safety distance model is established based on longitudinal relative speed or deceleration, without considering the lateral motion characteristics of moving target. In this paper, the relative speed and position of the moving target crossing the road are used to set up lateral safe distance model, and an active obstacle avoidance algorithm based on lateral safe distance model is proposed. Firstly, a lateral safety distance model is established according to the relative speed and position of the moving target crossing the road and the braking distance of ego vehicle, and the active obstacle avoidance algorithm is designed. Then, considering the influence of road conditions on braking effect, the predicted peak adhesion coefficient of current road surface is introduced to estimate the maximum braking deceleration, with the expected obstacle avoidance deceleration constrained to adjust braking intensity for adapting to the safe obstacle avoidance driving in different road conditions. Finally, with the typical lateral moving target-cyclist as research object, a PreScan/Simulink/Carsim co-simulation is conducted to verify the effectiveness of the obstacle avoidance algorithm. The results show that the active obstacle avoidance algorithm based on lateral safe distance model can effectively avoid vehicle collision with cyclist, so enhancing the active safety of driving References | Related Articles | Metrics

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Research on Active Drag Reduction of MIRA Fastback Model Zhang Yingchao, Zheng Zhenyu, Wu Kaiguang, Zhang Zhe 2020, 42 (5):  588-592.  doi: 10.19562/j.chinasae.qcgc.2020.05.004 Abstract ( 352 )   PDF (2640KB) ( 368 )   Save By referring to the mechanism of passive drag reduction, jet ports are set in several positions of MIRA body to realize jet air blowing, so as to reduce the pressure on the windward side of the model or increase the pressure on the leeward side. The simulation accuracy is verified by comparing the transient simulation and experimental results of the original MIRA model. The transient simulation results of several jet flow conditions and original model are compared and analyzed. By comparing drag coefficient, surface static pressure coefficient and directional vorticity, the drag reduction effects of local jet flow are ascertained, and a 16.3% reduction of drag coefficient is achieved in the end References | Related Articles | Metrics

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Investigation into Bonnet Aerodynamic Characteristics of Follower Vehicle in Two-vehicle Platoon at Different Reynolds Numbers Dai Wentong, Li Qiliang, Li Zhuoming, Chang Yifei, Yang Zhigang 2020, 42 (5):  593-599.  doi: 10.19562/j.chinasae.qcgc.2020.05.005 Abstract ( 301 )   PDF (3214KB) ( 409 )   Save The bonnet aerodynamic characteristics of follower vehicle and the flow field in the interspace between vehicles in a two-vehicle platoon are studied, and the flow patterns of scaled model and full scale vehicle model with corresponding Reynolds numbers for two-vehicle platoon are compared by both numerical simulation and model wind tunnel test. The results of simulation are consistent with wind tunnel test for the scaled model, indicating the feasibility of the numerical method adopted. The comparison of the aerodynamic characteristics of platoon at different Reynolds numbers shows that the average static pressure distribution on the bonnet surfaces for both the scaled model and full scale model are basically identical, but on the longitudinal symmetric plane, the tail trace of leading vehicle for full scale model is more up-wards with higher air-flow velocity in bottom area compared with the scaled model. Under unsteady condition and compared with the scaled model, the relative scale of tail vortex of leading vehicle for full scale model apparently smaller, its diffusion is more sufficient with more chaotic state of distribution, and the distribution of pulsating energy on bonnet surface is more disorderly. The movement of vortex in the interspace between vehicles is not a simple displacement but a complex process composed of breakup, pairing and fusing of vortex References | Related Articles | Metrics

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Study on a Novel Vehicle Spoiler and Its Aerodynamic Optimization Lai Chenguang, Si Yang, Chen Yi, Bai Haitao 2020, 42 (5):  600-607.  doi: 10.19562/j.chinasae.qcgc.2020.05.006 Abstract ( 312 )   PDF (3979KB) ( 336 )   Save In view of that traditional spoiler can only reduce aerodynamic drag or lift force, a novel spoiler, which can reduce both drag and lift force, is designed based on a square-back vehicle. Firstly, according to the flow field condition the spoiler should meet, the initial upper and bottom curves of the cross-section of spoiler are determined and fitted by quasi-uniform B-spline curve,and are drawn along y direction to form the surface of spoiler. Then a series of surfaces are obtained by changing the control points of section curves, among which an optimum surface is obtained by using genetic algorithm. Finally, for further reducing the drag and lift force, a further optimization is conducted by adopting the design of experiment, approximate model and NSGA-II genetic algorithm and changing the width and the installation position and angle of spoiler based on optimum surface of spoiler. The results of verification experiment on model wind-tunnel show that with the spoiler optimized the drag and lift force of vehicle reduce by 3.8% and 7.9% respectively References | Related Articles | Metrics

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Design and Verification of Pedestrian Protection Airbag Hu Shuaishuai, Lü Xiaojiang, Zhang Xiaotian, Zhang Haiyang, Hong Dan, Zhou Dayong 2020, 42 (5):  608-614.  doi: 10.19562/j.chinasae.qcgc.2020.05.007 Abstract ( 378 )   PDF (4100KB) ( 555 )   Save In recent years, more than 70% of the real traffic accidents in China are related to vulnerable road users, and the requirements for cars to protect them are becoming more and more prominent. Based on an A-class car, a vulnerable road user protection airbag (pedestrian airbag for short thereafter), which can protect their head and can be coordinated with pop-up bonnet, is designed and verified in this paper. First, the shape and layout of pedestrian airbag are designed and some operation conditions of pedestrian airbag including the collision of headform impactor against and linked deployment with pop-up bonnet are simulated. Then, by means of test and theoretical derivations, simulation results are validated and key parameters of pedestrian airbag and pop-up bonnet are revised. Finally, a C-NCAP headform collision test is conducted to investigate the protection effects of pedestrian airbag with pop-up bonnet. The results show that the pedestrian airbag developed has good protective effect of pedestrian head and can reduce injury by over 60% and get a high scoring rate up to 93.1% References | Related Articles | Metrics

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An Analysis on the Effect of Active Retractor Parameters on Occupant's Out-of-position Displacement Under Braking Condition Hu Yuanzhi, Zhu Hongxu, Zeng Xianjing, Wang Zhenfei, Xu Zihong, Jiang Chengyue 2020, 42 (5):  615-620.  doi: 10.19562/j.chinasae.qcgc.2020.05.008 Abstract ( 393 )   PDF (2322KB) ( 294 )   Save The active control retractor (ACR) is beneficial to the reduction of occupant's out-of-position displacement and the minimization of secondary impact risk. In order to investigate the effect of ACR on occupants in braking conditions, a volunteer real vehicle road test is conducted with occupant kinematics responses analyzed based on test data, and a simulation model including active human model is built. After the verification of simulation model, a Kriging approximation model is set up and an optimization on ACR parameters is conducted using NSGA-II algorithm. The results show that the out-of-position displacements of head mass center and the 1st thoracic spine (T1) are reduced by 55% and 73.44% respectively, the accelerations of all parts are lowered significantly during rebound phase, the pretension force and the occupant's out-of-position displacement shows a tendency of negative correlation, and compared with triggering before braking, the pretensioning time in triggering ACR after braking has a larger effect on the out-of-position displacement of occupant References | Related Articles | Metrics

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Comparative Study on the Injury Difference Between Motorcyclist and Occupant in Vehicle-motorcycle Collision Accidents Zou Tiefang, Wang Guan, Hu Lin, Wu Hequan 2020, 42 (5):  621-627.  doi: 10.19562/j.chinasae.qcgc.2020.05.009 Abstract ( 352 )   PDF (2651KB) ( 510 )   Save To explore the injury difference between motorcyclist and occupant, based on PC-Crash simulation software, with the vehicle type, collision speed and collision pattern as variables, a simulation on 147 sets of vehicle-manned motorcycle collisions is carried out. On this basis, the data obtained are analyzed by statistical methods. The results show that under most collision conditions including different collision speeds, the average value of injury indicators of the head, thorax and impact side lower limb of motorcyclist is higher than that of occupant. In addition, when the collision speed is 45 and 50 km/h respectively, the head and thorax injuries of both motorcyclist and occupant exceed their corresponding safety limits References | Related Articles | Metrics

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Optimization of Engine Mount Based on Sound Quality Contribution Factor Zeng Falin, Hu Feng 2020, 42 (5):  628-635.  doi: 10.19562/j.chinasae.qcgc.2020.05.010 Abstract ( 335 )   PDF (3714KB) ( 386 )   Save In this paper, a GA-BP sound quality prediction model is established and a sound quality contribution factor (SQCF) is introduced for more intuitively reflecting the contribution of structural noise transmission path to annoyance and the influence of masking effect on sound quality. Two-level optimization scheme is adopted to determine the target transfer function corresponding to the target annoyance by using genetic algorithm, and the parameters of engine mount are further matched. The results show that the engine mount optimization scheme based on sound quality contribution factor can effectively improve the interior sound quality of the car and reduce the contribution of the structural path to the annoyance caused by noise References | Related Articles | Metrics

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Vertical and Lateral Coupling Roll State Estimation of Vehicle System Wang Zhenfeng, Li Fei, Wang Xinyu, Gao Pu, Qin Yechen 2020, 42 (5):  636-643.  doi: 10.19562/j.chinasae.qcgc.2020.05.011 Abstract ( 447 )   PDF (3884KB) ( 395 )   Save To effectively solve the problem that the coupling roll motion state of vehicle cannot be accurately obtained under complicated driving conditions and the difficulty in providing accurate input for the concurrent optimization of vehicle handling stability and ride comfort, a dual nonlinear state observer algorithm based on vehicle vertical and lateral coupling dynamics is designed to achieve real time accurate estimation of vehicle coupling roll motion state under complicated driving conditions. Firstly, the road excitation model and vehicle vertical and lateral coupling dynamics model are established. Then by utilizing the unscented Kalman filtering (UKF) technique and the nonlinear fuzzy observation (T-S) theory, a nonlinear state observation algorithm is designed and a joint-estimation on the sprung mass and rolling state of vehicle system is conducted under different road excitation conditions. Finally, by applying dynamics software CarSim®, the observation accuracies of vehicle roll angle and rolling rate real time estimated by joint state observer UKF&T-S on standard A- and C-grade roads are comparatively analyzed under J-turn test conditions. The results show that the UKF&T-S observer designed can effectively estimate the roll state of vehicle, with a less than 10% standard deviation of identified state, compared with the CarSim® simulation data References | Related Articles | Metrics

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Research on Power Transfer Characteristics of Transfer Case with Temperature Prediction Compensation Control Wang Yuming, Wang Qidong, Li Hongliang, Chen Liqing, Gu Tianyi, Sun Jingjing 2020, 42 (5):  644-650.  doi: 10.19562/j.chinasae.qcgc.2020.05.012 Abstract ( 362 )   PDF (1183KB) ( 293 )   Save Transfer case is an essential component of the intelligent four-wheel drive vehicle, and its performance is affected by various factors during the process of torque transmission, especially by temperature change. Hence, it is crucial to evaluate the effect of temperature change on the torque output of transfer case accurately. In order to solve this problem, firstly, by predicting the temperature change of the friction plate, coil and lubricating oil during the transfer case joining process, the transfer case temperature control model is built. On this basis, the transfer case test platform is constructed. By the temperature compensation cooperative control of the test data obtained from the test platform and the feed forward controller, a temperature feedback compensation control system with time-delay of transfer case is built to analyze the dynamic transfer characteristics of transfer case under the influence of temperature. The results show that once the friction plate contacts the steel disk for many times, the temperature of the friction plate increases significantly, which has a significant impact on the torque transmission. The control current is linear related to the torque output of the transfer case basically. Considering the feedback compensation control, the output time of the transfer case power decreases by 0.05 s and the control error is nearly zero. This research can provide a theoretical basis for the accurate control of the transfer case References | Related Articles | Metrics

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Subjective Evaluation Model for Interior Sound Quality and Optimization of Medium-frequency Noise Zhang Yong, Meng Tian, Wang Kunxiang, Han Chenyang, Yang Echuan 2020, 42 (5):  651-657.  doi: 10.19562/j.chinasae.qcgc.2020.05.013 Abstract ( 319 )   PDF (3227KB) ( 496 )   Save In order to study the interior sound quality of special vehicles, the road tests of three different types of special vehicles are carried out, a Kriging model is established, describing the relation between subjective rating of annoyance and objective parameters of sound quality, and the effects of the objective parameters of sound quality on subjective evaluation results in different frequency bands are obtained by filtering analysis. A hybrid FE-SEA model is set up to calculate the interior medium-frequency noises, which are then compared with test data to verify model accuracy. The acoustic contribution of key panels to interior medium-frequency noises are calculated, based on which panels with larger contribution are found and optimized, thus the interior medium-frequency noises are effectively reduced References | Related Articles | Metrics

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Experiment Study on Heat Transfer Characteristics of Honeycomb Liquid Cooled Battery Module Feng Nenglian, Dong Shikang, Li Dezhuang, Chen Longke, Feng Shou 2020, 42 (5):  658-664.  doi: 10.19562/j.chinasae.qcgc.2020.05.014 Abstract ( 283 )   PDF (5314KB) ( 434 )   Save A novel honeycomb liquid cooled battery module is developed for a 21700 lithium-ion battery with a capacity of 4 A·h and a test platform is constructed to measure the heat-transfer characteristics of the battery module. The results show that under an ambient temperature of 25 ℃,the maximum temperature difference of the battery module is less than 2 ℃ in the processes of both 0.5C constant-current / constant voltage charging and 1C constant-current discharging. When the ambient temperature rises to 40 ℃ with a cooling liquid flow rate larger than 1 L/min, the maximum temperature difference of the battery module can maintain at below the limit value of 5 ℃ in the course of 1C constant-current discharging. It is demonstrated that honeycomb liquid cooled battery module has a good cooling performance, providing technical supports for the design of battery thermal management scheme in the future References | Related Articles | Metrics

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Study on Thermal Characteristics of Battery Modules of Electric Vehicle Based on Electrochemical Thermal Coupling Model Dai Haiyan, Wang Yuxing 2020, 42 (5):  665-671.  doi: 10.19562/j.chinasae.qcgc.2020.05.015 Abstract ( 347 )   PDF (1895KB) ( 366 )   Save In order to study the influence of the arrangement and spacing of the battery pack on the thermal characteristics of the batteries, the electrochemical thermodynamic coupling model of the single battery is established taking 18650 lithium-ion battery as the study object in this paper. The relationship between the surface temperature of the battery and the discharge capacity at different discharge rate is obtained by using the model simulation and experimental measurement, which are basically consistent and the model is accurate. Based on the coupling model, the thermal characteristics of 6×5 power battery modules in different arrangement and spacing are analyzed. The results show that too small or too large spacing will increase the average temperature, and the distance between adjacent batteries in this case is 24 mm when the average temperature is the lowest; the larger the spacing, the smaller the temperature difference, and the better the uniformity of temperature distribution; with a certain spacing, the heat dissipation effect of cross arrangement is better than that of alignment arrangement, and the space utilization ratio is higher. Therefore, the arrangement and spacing of the batteries have an important influence on the heat dissipation of the batteries, which should be fully considered in the design process of the lithium-ion power battery pack References | Related Articles | Metrics

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Research on Microchannel Structure Optimization of Electric Vehicle Battery Cold Plate Wang Jingyu, Yan Wei, Li Song, Hu Xingjun, Sang Tao, Wang Mo 2020, 42 (5):  672-680.  doi: 10.19562/j.chinasae.qcgc.2020.05.016 Abstract ( 307 )   PDF (4320KB) ( 427 )   Save In order to optimize the structure of the cold plate of the micro channel of the vehicle battery and explore the interaction mechanism between the flow field and the temperature field in the cold plate flow channel, the optimal layout of the cold plate is first obtained using orthogonal experiments in this paper. By using the Face-Centered Central Composite Design (FCCCD), it is found that when the wavy channel amplitude is 1 mm and the number of cycles is 4, the overall thermal-hydraulic performance of the wavy channel reaches the maximum, which increases by 17.4 % compared to the straight channel. According to CFD analysis, the consistency of the field synergy angle and the channel Nusselt number proves that the field synergy angle theory can be used to explain the enhanced heat transfer in the micro channel. The chaotic advection in the flow channel caused by the curvature of the wavy channel greatly enhances the convective fluid mixing and destroys the shear layer, which separates the main flow and the recirculating flow in the channel, resulting in a heat transfer enhancement References | Related Articles | Metrics

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Study on Battery SOC Estimation by Ampere-hour Integral Method with Capacity Correction Luo Yong, Qi Pengwei, Huang Huan, Wang Jianan, Wang Yi, Li Peiran 2020, 42 (5):  681-687.  doi: 10.19562/j.chinasae.qcgc.2020.05.017 Abstract ( 420 )   PDF (2185KB) ( 537 )   Save In view of the error caused by that the SOC estimation algorithm based on traditional ampere-hour integral method regards battery capacity as constant, a modified ampere-hour integral method with capacity correction is proposed, in which the initial SOC value of battery is determined by open circuit voltage and then corrected by correction factors related to charge/discharge current, coulombic efficiency and temperature, obtained by the charge and discharge tests of battery pack. The results of simulation and tests show that the modified ampere-hour integral method can effectively eliminate various errors and get more accurate estimation results, so it can be used in real time estimation of SOC or as a reference for the evaluation of other SOC estimation strategies References | Related Articles | Metrics

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Experimental Study on Energy Flow in a Plug-in Hybrid Electric Vehicle at Low Battery SOC Zhang Yan, Duan Lian, Yuan Xiayi, Jiang Liang, Xu Yanghui, Lan Fengchong 2020, 42 (5):  688-693.  doi: 10.19562/j.chinasae.qcgc.2020.05.018 Abstract ( 461 )   PDF (3702KB) ( 566 )   Save In order to formulate the optimal energy allocation strategy, the energy flow of a plug-in hybrid electric vehicle in different operation conditions are analyzed. The related parameters of the energy transfer between vehicle components including temperature, pressure, torque, rotating speed and flow rate at low-SOC states are measured by tests, the energy distribution of vehicle is calculated and analyzed, and the energy flow and energy recovery rate under new European driving cycle (NEDC) and worldwide harmonized light vehicles test cycle (WLTC) are compared. The results show that when battery SOC is low, the average fuel consumption of engine under WLTC cycle is about 1.6 times of that under NEDC cycle and the most energy consumed in vehicle driving under both cycles comes from engine. In addition, the energy consumed in driving under WLTC cycle is less than that under NEDC cycle with a difference smaller than 1%, while the energy recovery rate under WLTC cycle is lower than that under NEDC cycle with a little more difference of 2.31% References | Related Articles | Metrics

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Study on Low-speed Impact Performance and Application of Basalt Fiber/Aluminum Alloy Laminates Cui An, Yang Weili, Cheng Pu, Jin Weiguang, Xü Xiaoqian, Liu Tianci, Huang Xianqing 2020, 42 (5):  694-699.  doi: 10.19562/j.chinasae.qcgc.2020.05.019 Abstract ( 275 )   PDF (3416KB) ( 341 )   Save A composite structure composed of basalt fiber and aluminum alloy laminates are manufactured and its tensile, compression, shear, bending and anti-impact characteristics are explored by test and simulation. Then, a low-speed impact simulation model is set up with fiber layer simulated by continuous shell element, and the effects of ply laying structure and the angle of impact load on the anti-impact performance of fiber-metal laminates are studied in terms of energy absorption, contact force and laminate damage degree. Finally, fiber-metal laminates are applied to the external panel of engine hood and a simulation on the static stiffness and pedestrian head collision is also performed. The results show that compared with original engine hood, the bending and torsional stiffness of engine hood using fiber-metal laminates are enhanced to different degrees with pedestrian head protection performance improved References | Related Articles | Metrics

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Dynamic Load Emulation of Dynamometer with Compensation for Stochastic Network Time-delay Ma Ruihai, Wang Lifang, Zhang Junzhi, He Chengkun 2020, 42 (5):  700-708.  doi: 10.19562/j.chinasae.qcgc.2020.05.020 Abstract ( 302 )   PDF (1455KB) ( 418 )   Save A novel dynamometer loading control algorithm is studied with consideration of the effects of control network transmission time-delay in this paper. Firstly based on a front drive electric vehicle, the dynamic coupling model for vehicle and test bench and the mathematical model for the stochastic network-induced time-delay with uniform distribution are constructed. Then, a compensation algorithm for stochastic network-induced time-delay based on predictive control structure is proposed to improve the load emulation performance of dynamometer network control system. Next, the problem of stochastic system tracking control is transformed into a robust stabilization issue by system augmentation, the H∞ performance is analyzed and the system control gains are obtained through nonlinear optimization. Finally, a simulation on bench test for anti-lock braking control is conducted with a result showing that the scheme proposed can greatly enhance the load emulation accuracy of dynamometer References | Related Articles | Metrics