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  • 2023 Volume 44 Issue 3
    Published: 10 May 2023
      
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  • Optimization of safe distance model considering driver difference
    LI Shengqin, DU Peng
    2023, 44(3): 249-253. https://doi.org/10.3969/j.issn.1671-7775.2023.03.001
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    The traditional model sets the driver response time as fixed value, and the driver difference is ignored, which can lead to the error of collision warning. To optimize the problem, a safe distance model was proposed with considering the driver difference. The three factors of driver′s driving age, driving style and speed were selected as characteristic values, and the response time of the driver was calculated by fuzzy control algorithm. Based on Honda model, a safe distance model considering the driver difference was established. According to the Chinanew car assessment program (CNCAP), the braking condition of the front car was selected to carry out the simulation test for verifying the proposed safe distance model. The results show that the proposed model has good realtime performance and adaptability under the above conditions. The safe distance model not only ensures the driving safety, but also the response time of the driver can reflect the differences of different types of drivers to improve the driving safety.
  • Driving force control of wheel motor drive skid steer vehicle
    ＦＵ Ｘiang， ＺＨＡＯ Ｘijin， ＬＩＵ Ｄaoyuan
    2023, 44(3): 254-261. https://doi.org/10.3969/j.issn.1671-7775.2023.03.002
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    To improve the maneuverability and stability of the skid steer vehicle driven by hub motors, the advantages of torque vectoring control in vehicle dynamics were fully utilized. To solve the chattering problem in traditional sliding mode control, a direct yaw moment control method was proposed based on adaptive fuzzy sliding mode control (AFSMC). The AFSMC controller was designed to calculate the additional yaw moment for following the control target, and a fuzzy system was constructed to approximate the variable gain sign function in real time. The fuzzy adaptive law was derived through the Lyapunov method to enhance the robustness of the control strategy and suppress output control chattering. For the lower level, an optimized driving force distribution scheme based on tire load rate and weighting factors was proposed by establishing an objective function. In the proposed strategy, the nonlinear dynamic characteristics of the vehicle was fully considered. The experimental results on a real vehicle show that by the proposed control strategy, the good performance in vehicle handling and stability can be achieved with strong robustness of the control system.
  • Vision detection method of car body relative parking position based on closerange images of binocular lens
    ZHANG Xiliang， YAN Yan， LIU Yuqin, YUAN Chaochun
    2023, 44(3): 262-269. https://doi.org/10.3969/j.issn.1671-7775.2023.03.003
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    To improve the single application adaptability of machine vision technology in the field of automatic parking to the orientation detection of the target empty parking space, a new  machine vision detection method for the relative position of  car body was investigated based on the closerange image of  binocular lens. The closerange image of the parking space was collected through the binocular lens. Through the image processing of image correction, image mosaic, inverse perspective transformation and image binarization, the contour edge of the target empty parking space on the top plane and the position point of the binocular lens were extracted. The coordinate system of the vehicle body relative to the target empty parking space was established, and the coordinates of the binocular lens in the twodimensional coordinate system of the parking space were determined through visual recognition and pixel point coordinate calculation. Based on the known parking space and car size, the position of fisheye lens on the car body and other information, the calculation relationship model between the azimuth and distance of the car body relative to the parking space was established by geometric method. The results show that the maximum relative error of azimuth detection is 916%, and the maximum relative error of range detection is 389%, which improves the adaptability of target empty parking space detection
  • Trajectory tracking control of driverless vehicle based  on road adaptive model predictive control
    GUO Pan, YU Leiyan
    2023, 44(3): 270-275. https://doi.org/10.3969/j.issn.1671-7775.2023.03.004
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    To solve the problems of narrow driving condition range, partial evaluation method and insufficient road adaptive control of trajectory tracking, the trajectory tracking accuracy and driving safety under full speed and full road adhesion coefficient were investigated. In the road adaptive model predictive control(MPC), the discrete linear timevarying predictive model was obtained by the threedegreeoffreedom nonlinear dynamic model of the vehicle. The road adaptive speed range matching was realized according to the road adhesion coefficient detected by sensors, and the constraint condition of the speed increment was formulated. The maximum and standard deviation of path tracking error, lateral acceleration, centroid sideslip angle and front wheel sideslip angle with the change of velocity and road adhesion coefficient were obtained by integrating CarSim and Matlab softwares. Combined with the mechanism of tire sideslip, the driving safety was evaluated，and the trajectory tracking stability/ instability area of vehicle under all working conditions was divided. The results show that the vehicle speed can be adaptively adjusted according to the road information to achieve excellent trajectory tracking accuracy and driving safety under all working conditions.
  • Experiment on pulsating heat pipe heating technology for pure electric vehicle power batteries
    CHEN Meng, LUO Xinhao
    2023, 44(3): 276-282. https://doi.org/10.3969/j.issn.1671-7775.2023.03.005
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    As the working fluid of pulsating heat pipe (PHP) for the power battery heating element, TiO2 nanofluid was prepared with distilled water and ethanol as base solution to ensure the operating properties of the power battery at low temperature. The experimental study on the heating performance of power batteries in low temperature environment was carried out. The experimental results show that the thermal transport property with ethanol is better than that with distilled water at low temperature. When the volume fraction of nano TiO2 fluid is 2% with heat pipe filling rate of 50%, the thermal property of PHP is significantly improved with the optimum performance of PHP at low temperature. For the optimal working medium ratio of ethanolbased liquid, the maximum cell capacities of titanium dioxide nanofluid pulsating heat pipe (TiO2PHP) under the charge and discharge modes in low temperature environment can reach  6291 A·h. In the extremely cold environment of -30 ℃, using the designed heat pipe as heating element to heat the electric vehicle power battery, the improvement of 6156 A·h from the initial discharge failure can be achieved. The designed TiO2PHP has efficient heating performance and thermal conductivity.
  • Research progress on anode emission of proton exchange membrane fuel cell
    CHEN Ben, LIU Yang
    2023, 44(3): 283-292. https://doi.org/10.3969/j.issn.1671-7775.2023.03.006
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    The anode operation mode of proton exchange membrane fuel cell (PEMFC) mainly includes openend mode, deadend mode and recirculation mode. Different working anode modes lead to different ways of hydrogen emission from anode outlet. The emission study of PEMFC under different anode operation modes was summarized. The results show that in the anode openend mode, the tail hydrogen is directly discharged from the outlet, resulting in serious waste of hydrogen. The hydrogen efficiency can be improved by blending and anode cascade operation mode. The deadend anode PEMFC has the advantages of simple structure and high hydrogen efficiency. However,  ″water flooding″ and nitrogen accumulation seriously affect the performance and durability of PEMFC. The disadvantage can be improved by optimizing anode emission strategy. The anode recirculation mode has the advantages of both high performance and high efficiency. The recirculation mode includes active recirculation based on mechanical recirculation pump or electrochemical hydrogen pump and passive recirculation based on ejector, and the anode discharge mode is mainly based on periodic blowing discharge.
  • Individual plant extraction and counting from field images based on leaf matching
    ZHANG Liankuan, XIAO Deqin, CEN Guanjun, YU Yonghao
    2023, 44(3): 293-301. https://doi.org/10.3969/j.issn.1671-7775.2023.03.007
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    A method was constructed to extract individual plant image from the continuouslycollected images. The leaf surface region segmentation was obtained，  and the individual plant image was separated based on leaf surface image by leaf distance. The two consecutive adjacent images were stitched together, and the newlyformed images were transformed and stitched with empty images to produce individual plant image for determining the centroid. The distance between the centroid of all stitched images in the previous image and the centroid of all the stitched images in the subsequent image was compared. The distance threshold method was used to identify whether the two images were the images of the same crop. Transfer closure was applied for obtaining the plant image set of each crop in multiple continuous images, and the image closest to the center was selected as the best image. Five crops were used to verify the proposed method. The results show that the accuracy of plant number reaches 100%. The proposed method can successfully and precisely extract individual plant image with high computational efficiency.
  • Simulation analysis of picking head height adjustment device of cotton picker based on AMESim
    DONG Jianhao, YU Aijing, LI Wenchun, BI Xinsheng, LI Juanjuan, TAN Fei
    2023, 44(3): 302-308. https://doi.org/10.3969/j.issn.1671-7775.2023.03.008
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    To solve the problem that the picking head of cotton picker could not adjust automatically according to the fluctuation of the ground height in time, a ground height adjusting device for the picking head of cotton picker was designed. The key components of the device was composed of copying mechanism, lifting mechanism and hydraulic control system. Through theoretical analysis, the maximum thrust of the hydraulic cylinder in the whole process of motion was 62 28856 N, and the parameters of the hydraulic system were obtained according to the motion conditions of the lifting mechanism. The model of the lifting mechanism and the hydraulic system of the height adjustment device was established based on the AMESim simulation software. After the simulation, the flow, displacement, speed, the force of piston rod and the motion characteristics of the lifting mechanism of  hydraulic system of the height adjustment device of picking head were analyzed. The results show that the simulation results are consistent with the theoretical analysis to meet the requirements of the height adjustment of the picking head， and the accuracy of the theoretical calculation is verified.
  • Design and coordination test of automatic Salix planter
    WANG Hui, HONG Chen, CHEN Anyu, ZHAO Xinyu, LI Xiongfei, ZHANG Cunyi
    2023, 44(3): 309-317. https://doi.org/10.3969/j.issn.1671-7775.2023.03.009
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    To realize automatic planting of Salix psammophila forest, an automatic Salix  planter was designed for heavily sandy area. According to the cottage requirements of Salix, the functions of various planting machinery were integrated, and the overall structure of planter was proposed and designed with seedling storage device, ditching device, pushing device, sorting and seeding device and soil filling device to realize the main functions of cutting planting. The SOLIDWORKS software was used to establish the model, and the strength of the platform was simulated and analyzed to verify the effectiveness of the structure. Based on the whole structure, a single chip microcomputer control system scheme was provided to realize automatic operation of the planter. On the basis of the above design and simplifying structure, the experimental prototype for testing was manufactured according to the proportion, and the coordination in the working process of the planter was analyzed. The experiment results show that the designed scheme is effective, and each device of the planter can work in coordination to realize safe and efficient planting of cuttings.
  • Handheld call detection of driver based on improved Faster RCNN
    WANG Bin, LI Xiaoman, ZHAO Zuopeng
    2023, 44(3): 318-323. https://doi.org/10.3969/j.issn.1671-7775.2023.03.010
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    To solve the problem of high false positive rate of existing driver call behavior recognition, an improved Faster RCNN was proposed based on driver behavior detection method for detecting the illegal handheld call of driver. An optimization strategy for the region proposal network (RPN) and the loss function was introduced, and the robustness of the network in detecting targets with different sizes was enhanced by applying multiscale training, increasing the number of anchor points and introducing the residual expansion network on the original Faster RCNN. The simulation experiments of the proposed method were conducted with the images of driver behavior collected on an invehicle platform. The results show that compared with original Faster RCNN, RPN and Faster RCNN can realize efficient target detection by alternatively optimizing the shared feature extraction network part with 38% improvement in detection precision and better adaptation to the environment.
  • Reading technology of pointer instrument based on Deming regression and ROI thinning
    XU Xiaoqiang, CHEN Xu, MAO Yan
    2023, 44(3): 324-329. https://doi.org/10.3969/j.issn.1671-7775.2023.03.011
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    To solve the problems of low recognition accuracy and slow reading speed of the algorithm in reading the indicator of pointer instrument, a reading technology of pointer instrument based on Deming regression and region of interest (ROI) thinning was proposed. The algorithm flow of reading the indicator of the instrument was given. ROI was selected, and the image preprocessing was carried out by the color channelbased silhouette method and binary morphology operation. The image frame difference method was used to eliminate pointer jitter, and ROI thinning algorithm was used to refine the pointer of instrument to be identified. Deming regression method was used to fit the equation and slope of the straight line where the pointer of instrument was located. According to the pointer slope, the angle method was used to calculate the realtime reading of the instrument. Through three sets of experiments, the feasibility and antijitter ability of the method were tested, and the detection accuracies of the fitting line by Deming regression and the fitting line by Hough line detection were compared. The calculation speeds of the ROI thinning algorithm and the global thinning algorithm were also compared. The results show that the average error of the proposed method is 37.85% less than that of Hough line detection, and the average calculation time of each image is 192717 s less than that of the global thinning algorithm. At the same time, the proposed method has the ability of antijitter.
  • Speed control of permanent magnet synchronous motor  based on RESO and composite sliding mode
    LI Juan, FENG Bo, LI Shengquan, WANG Shuwang, AI Wei
    2023, 44(3): 330-336. https://doi.org/10.3969/j.issn.1671-7775.2023.03.012
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    To solve the internal and external disturbances in permanent magnet synchronous motors (PMSM) with parameter variations, modeling error and load uncertainties, a reducedorder extended state observer (RESO) based on composite sliding mode control strategy was proposed. Based on the state space model, a novel RESO was designed to estimate and eliminate the internal and external disturbances with considering the speed signal of PMSM measured by the encoder, and the performance for the RESO was analyzed. The composite sliding mode control method was introduced to design the sliding mode surface and control law for improving the antiance ability of the whole control system, and the stability of the control strategy was analyzed by Lyapunov method. The hardwareintheloop speed control platform of PMSM was built based on the control core of DSP chip TMS320F28335 and the MATLAB control module. The proposed method was simulated and compared with traditional PI and linear active disturbance rejection control methods. The results show that the  speed variation of the system with loading can be reduced more than 60% in contrast to traditional system with excellent performance of antidisturbance and regulation speed.
  • Self-correcting composite active disturbance rejection control of maximum power model for wind turbines
    MO Yueping， XU Di, SHI Hongjun, ZHU Qixin
    2023, 44(3): 337-343. https://doi.org/10.3969/j.issn.1671-7775.2023.03.013
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    To improve the maximum power tracking efficiency of permanent magnet synchronous wind generator under variable working conditions, a model selfcorrecting composite active disturbance rejection control (MSCADRC) based on the optimal blade tip speed ratio method was designed to track the motor speed in real time.  An extended state observer (ESO), which could switch freely between linear and nonlinear, was used for realtime observation and estimation of the total disturbance caused by parameter perturbation or other uncertainties. 
    A realtime predictive inertia observer of torque and moment was used to compensate the influence of parameter disturbance in the controller on ADRC.  In the current loop ADRC control,
    qaxis current compensation factor was added to eliminate the interference of daxis current, and the feedback compensation control method based on electromagnetic torque observer was adopted to realize the realtime compensation of qaxis current for accelerating the system response speed.  The mathematical model of wind speed, wind machine and permanent magnet synchronous generator was used to design the wind power model selfcorrecting maximum power tracking system, and the Matlab/Simulink was used for simulation analysis. The simulation results show that the model MSCADRC has superiority. The wind power system under selfcorrecting model can perform better on power tracking control when wind speed changes sharply,  and the system response speed and antiexternal interference ability can be further improved.
  • Dynamic characteristics of electrostatic atomized microjets between needle and plate electrodes
    WANG Zhentao, CHEN Yongzhong, KONG Qian, YANG Shiqi, WANG Qisi, CEN Qigang
    2023, 44(3): 344-350. https://doi.org/10.3969/j.issn.1671-7775.2023.03.014
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    To realize the controllability of droplet size, velocity and spatial distribution characteristics generated by electrostatic atomization, the dynamic characteristics of electrostatic jet under different liquids, electric voltage and flow rate were experimentally investigated. The transient process of the electrostatic atomization was visualized, captured and analyzed through highspeed camera. By analyzing many highspeed images, the morphology difference of liquid filament between liquid drop and meniscus under various liquid properties, typical jet forms of pulsating and stable cone jets, and reference parameters range for propylene glycol and noctanol in different modes were obtained. The results indicate that in the conejet mode, the initial jet velocity from the meniscus is close to theoretical value. The varicose instability is found in the breakup of jet for propylene glycol and noctanol. The position of jet breaking point is changed with time and is mainly focused around twelve times dimensionless length ratio of jet breaking length to outside diameter of capillary nozzle. When the applied voltage or the liquid flowrate is too large, the stable cone jet mode is difficult to maintain and is gradually transformed into bifurcation, unstable multijet, oscillating jet and other unstable spraying modes.
  • Effect of pre-corrosion of NaCl solution on surface cavitation erosion of 304 stainless steel
    LIU Haixia， OUYANG Yadong， CHEN Jie， LIU Guanglei， YU Hui
    2023, 44(3): 351-358. https://doi.org/10.3969/j.issn.1671-7775.2023.03.015
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    To explore the effect of corrosion on cavitation erosion, the experiment was performed on corrosion and cavitation erosion of 304 stainless steel samples. Different concentrations of sodium chloride solution were adopted for corrosion. The experiments of cavitation erosion were conducted based on the waterjet cavitation test bench conforming to ASTM G134—95 of standard test method for erosion of solid materials by a cavitating liquid jet. The cavitation erosion characteristics of the 304 austenitic stainless steel samples were comprehensively analyzed according to cumulative mass loss, surface morphology and surface roughness. The analysis results show that the corrosion degree of 304 stainless steel is weakened first with latter strengthening by increasing the concentration of NaCl solution. The corrosion of NaCl solution contributes to the delay of cavitation erosion in a certain concentration, and the delaying effect is enhanced first with latter mitigating with the increasing of NaCl solution concentration. The minimum cavitation erosion is obtained at the concentration of NaCl solution of 35%. For the same corrosion time and cavitation erosion time, the plastic deformation is strengthened, and the thickness of twin layer of tested samples is gradually increased with the increasing of NaCl solution concentration, while the cumulative mass loss and the surface roughness are decreased first with latter increasing during the process. Compared to the sample undergoing cavitation erosion, the sample suffering from corrosion and cavitation erosion is featured by relatively slight cavitation erosion and smooth surface. Due to the cavitation erosion, the grains are preferentially oriented and refined.
  • Analysis and comparison of approaches for determining horizontal bearing capacity of rocksocketed pile
    ZHAO Xueliang, ZHANG Jingfei, HUANG Yue, HE Runcai, WANG Hongqing, TIAN Weihui
    2023, 44(3): 359-366. https://doi.org/10.3969/j.issn.1671-7775.2023.03.016
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    The existing method and theory for determining the horizontal bearing capacity of rocksocketed pile, including subgrade reaction method and elastic continuum method were summarized and analyzed. The results from different methods were compared based on the insitu test data, and the validity and limitations of the different methods were discussed. The results show that the accuracy of subgrade reaction method depends mainly on experience. The linear elastic subgrade reaction methods of constant method and Matlock method with single parameter are relatively simple, but it is difficult to determine the parameters for rocksocketed pile in the absence of field test data. The py curve method is more suitable for the pile with large deformation because it reflects the nonlinear reaction of foundation. However, the py curve method proposed by Reese overestimates the stiffness of the rock mass, and the validation of the py curves for rocksocketed pile is still inadequate. In the elastic continuum method, the continuity of rock is considered, but it is difficult to include the complex effects in practical engineering.
  • Mechanical properties of SAP internal curing machinemade sand  concrete and BP neural network prediction
    LIU Ronggui, CHEN Hao, CUI Zhaowei, CHEN Yeqiang, ZHANG Shaofeng, YAN Qianxun
    2023, 44(3): 367-372. https://doi.org/10.3969/j.issn.1671-7775.2023.03.017
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    The machinemade sand concrete was mixed with different amounts of super absorbent polymer (SAP) and stone powder, and the compressive strength and flexural strength tests were carried out to investigate the influence of SAP on the mechanical properties of machinemade sand concrete with different amounts of stone powder. Back propagation(BP) neural network was used to predict the compressive strength. The results show that the compressive strength of machinemade sand concrete at various ages is increased first with latter decreasing by increasing SAP content. When SAP content is 008%, the compressive strength is the highest. The addition of 008% SAP can significantly increase the compressive strength with the mixing of various stone powders. The compressive strength of concrete mixed with 9% stone powder has the best effect. The flexural strength of concrete with different stone powder content is decreased first with latter increasing and decreasing by increasing the SAP content. When SAP content is 016 %, the flexural strength reaches the maximum value, and the optimal mixing amount is 016% SAP with 6% stone powder compound. According to the prediction of 48 sets of compressive strength test data, the predicted value is well consistent with the test value.