Table of Content

15 November 2021 Volume 34 Issue 11

  

Numerical Simulation Analysis of Temperature Field in LaserCladding of FL-DLight3-4000 Laser

XU Yangyang,SAN Hongjun,CHEN Jiupeng,XIE Feiya,WEI Shunxiang,WANG Wanglin,LIU Liang,CHEN Jia

Electronic Science and Technology. 2021, 34(11):  1-10.  doi:10.16180/j.cnki.issn1007-7820.2021.11.001

Abstract ( 435 )   HTML ( 578 )   PDF (4672KB) ( 84 )  

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Laser cladding technology has a huge development prospect. In this study, the temperature field of matrix during laser cladding is simulated using the life and death unit method in ANSYS, and the moving rectangle heat source is loaded by APDL language. Through the simulation of the temperature field, the influence of different laser power and scanning speed on the temperature field are obtained. The higher the power, the less the time it takes for the matrix (45 steel) to rise to the same temperature at the same time. The faster the scanning speed is, the slower the substrate heats up at the same time. The end effect problem in laser cladding is preliminarily explored, and the results show that the end effect problem can be solved more effectively by adopting the reserved scheme. Finally, based on the robot control of FL - DLight3-4000 laser is tested. A side-axis powder feeding nozzle is used for powder feeding, the laser power is set to 3 kW, the scanning speed is 0.005 m·s^-1, and the powder feeding rate is 25 g·min^-1. The temperature at different times at 25 mm from the center of the first cladding layer is measured, and compared with the simulation results in ANSYS, which proves that the test results are basically consistent with the simulation results.

UAV Vehicle Target Detection Based on Faster R-CNN

ZHANG Ying,LIU Zilong,WAN Wei

Electronic Science and Technology. 2021, 34(11):  11-20.  doi:10.16180/j.cnki.issn1007-7820.2021.11.002

Abstract ( 789 )   HTML ( 32 )   PDF (4668KB) ( 117 )  

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There are disadvantages such as low resolution, low completeness, and many interference items in the UAV's perspective targets. Additionally, the research progress of UAV target detection system is slow, and its detection accuracy for small targets, incomplete targets and overlapping targets cannot meet the actual needs of society. In view of these problems, this study proposes a vehicle target detection solution for UAV platform based on Faster R-CNN. This solution uses ResNet convolutional neural network as the feature extraction network, improves the network structure, redesigns Anchor generation and improves the Soft-NMS algorithm and other strategies, solves the problem of low detection accuracy of small targets, incomplete targets and overlapping targets, and improves the accuracy of UAV vehicle detection. The test experiments on the dataset constructed in this study show that the proposed algorithm has 13.46% increase in AP value compared with the previous improvement. Test experiments on the public data set show that compared with the current mainstream algorithms, the proposed algorithm has better AP value and recall rate.

Research on Flexible Smart Logistics Platform Based on Digital Carrier

YE Hanglu,HE Lili

Electronic Science and Technology. 2021, 34(11):  21-25.  doi:10.16180/j.cnki.issn1007-7820.2021.11.003

Abstract ( 370 )   HTML ( 13 )   PDF (1671KB) ( 39 )  

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The rapid development of the Internet of Things technology has laid the foundation for the automation and intelligence of warehouse management, and digital carrier technology is the core of establishing a smart warehouse logistics platform. In view of the problem of low efficiency and low accuracy of manual data collection in traditional warehouse management, this study takes the warehouse warehousing operations in the manufacturing workshop as the object, and designs an RFID-based warehouse management system including the management layer, the middle layer and the physical layer. The system can optimize the process of traditional warehousing links, dynamically and intelligently perceive management objects, and realize effective management and monitoring of warehouse management. The simulation model is established by Flexsim software to simulate the storage process, and the model entity is simulated in a short period of time, and the utilization rate of each equipment is analyzed, which provides a reference for the platform design to propose improvements and decision-making.

Improvement of RLS Algorithm Based on Regularization Model

SUN Shuai,LIU Zilong,WAN Wei

Electronic Science and Technology. 2021, 34(11):  26-30.  doi:10.16180/j.cnki.issn1007-7820.2021.11.004

Abstract ( 324 )   HTML ( 15 )   PDF (740KB) ( 57 )  

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For the clutter signal interference existing in the research of antenna signals, the RLS algorithm is commonly used for filtering processing. However, the forgetting factor of conventional RLS algorithm is usually fixed, which cannot meet the requirements of fast tracking speed and small stability error at the same time. To solve the above problems, this study proposes an improved RLS algorithm based on regularization model. By adding an improved function, the forgetting factor can increase variability, and the inverse matrix equation of the autocorrelation matrix can be improved. The added correlation restriction condition can reduce the noise of the clutter signal to the original signal, and the existence and uniqueness of the noise reduction effect are ensured, thus greatly reducing the interference of the clutter. The waveform diagram of this experiment show that compared with the conventional RLS algorithm, the improved algorithm has stronger tracking capability and stability.

Research on Depth Image Preprocessing Algorithm

WU Haibo,WANG Chen,CUI Yu

Electronic Science and Technology. 2021, 34(11):  31-36.  doi:10.16180/j.cnki.issn1007-7820.2021.11.005

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In order to solve the problem that the original depth image data acquired by RGB-D camera contains noise and holes, a depth image filtering algorithm based on color image guidance is proposed in this study. The proposed algorithm is based on the principle of bilateral filtering. First, the color image is used as a guide map, and the gray pixel change weight of the color image is multiplied by the Gaussian filter weight to obtain the comprehensive filter weight. Then, the algorithm uses the separation characteristic of the Gaussian kernel function to reduce the computational complexity and improve the running speed of the algorithm through fast Gaussian transformation. Experimental results show that after filtering the original depth image, the algorithm can significantly improve the denoising effect of depth image. Additionally, the algorithm can repair the small-area void area of the depth image while maintaining the advantages of bilateral filter denoising and edge preservation, and shorten the running time.

A Method of Measuring Optical Fibers’ Mode Field Diameter Based on Two-Segments Polynomial Function Fitting

TAO Jiaqing,HU Yue,XIANG Huazhong,TU Jiankun,ZHENG Gang

Electronic Science and Technology. 2021, 34(11):  37-41.  doi:10.16180/j.cnki.issn1007-7820.2021.11.006

Abstract ( 395 )   HTML ( 9 )   PDF (681KB) ( 50 )  

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The mode field diameter of optical fiber is very important for evaluating the performance of optical fiber. The far-field variable aperture method is commonly used to measure the mode field diameter in industry. At present, more and more apertures are needed in various measuring instruments based on the far-field variable aperture method, which results in long measurement time and low efficiency. In view of this problem, this study uses the optical power data measured by the OFM optical fiber measuring instrument, and applies the two-stages polynomial function fitting method to the processing of the mode field diameter. The experimental results show that the stability of the measurement results at 20 apertures is better than that of the original direct fitting method. On the premise of meeting the measurement accuracy, the original 20 apertures can be reduced to 10 apertures. The proposed method improves the measurement speed of the instrument and can meet the needs of optical fiber manufacturers for rapid testing in on-site quality control.

Research Progress of Vehicle Positioning and Communication Network Protocol

WAN Zhuang,XIE Jian,ZHAO Xun,QIN Jie

Electronic Science and Technology. 2021, 34(11):  42-45.  doi:10.16180/j.cnki.issn1007-7820.2021.11.007

Abstract ( 290 )   HTML ( 12 )   PDF (552KB) ( 40 )  

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On-board communication and positioning methods can assist subway vehicles in understanding themselves and the surrounding environment, and are an important part of realizing communication-based train control. In-vehicle positioning and communication technology integrates its own theoretical development, and combines research results in multiple fields to develop related theories and technical methods suitable for various application needs. The study summarizes and sorts out a variety of on-board positioning technologies for the subway operating environment, the evaluation standards of positioning methods and the related research results of subway on-board communication networks. Benefit from the rapid development of environmental perception technology, computer technology and control decision-making technology, the vehicle positioning and communication technology has rapidly developed. With the improvement of subway intelligence, on-board positioning and communication technology will develop in a direction that is more robust and more integrated.

Motions Analysis and Simulation of a Parallel Robot with Four Degrees of Freedom

HU Qiongqiong,SAN Hongjun,CHEN Jiupeng,XIE Feiya,CHEN Zhongping,LI Pengyu

Electronic Science and Technology. 2021, 34(11):  46-54.  doi:10.16180/j.cnki.issn1007-7820.2021.11.008

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In this study, the mechanical characteristics of the 3-TRT / SPS parallel robot are analyzed using the position and orientation characteristics theory. The aggregation of position and orientation characteristics and the degree of freedom of the robot are obtained, which are consistent with the expectation of robot mechanism configuration synthesis. The forward and inverse kinematics of the position of the parallel robot is analyzed using the analytic method. The results indicate that the forward and inverse kinematics algorithm are effective and feasible, and verify the rationality of the structural design of the parallel robot. The polar search method are utilized to solve the workspace of the 3-TRT/ SPS parallel robot, and the influence of different structural parameters on the workspace is compared. In the case of the same mechanism parameters, the working spaces of the 3-TRT/SPS parallel robot and the 3-PTT parallel robot are compared, and the results show that the 3-TRT / SPS parallel robot has a broader range of applications than the 3-PTT parallel robot.

Research on Flexible Switching Controller Based on UPFC

WANG Yumei,LI Yaowei

Electronic Science and Technology. 2021, 34(11):  55-61.  doi:10.16180/j.cnki.issn1007-7820.2021.11.009

Abstract ( 244 )   HTML ( 7 )   PDF (1036KB) ( 32 )  

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The busbar switch directly performs rigid closing during the power system switching operation, and a large inrush current will be generated in the ring network, which seriously threatens the safe operation of the power system. Thus, a flexible switching controller based on UPFC is designed. By analyzing the topology structure and working principle of the unified power flow controller, the topology structure of the controller suitable for the busbar switch tripping is proposed. The parallel structure of the tripping controller is designed to adjust the voltage amplitude during closing, and the controller series structure is designed to adjust the voltage phase. The simulation verification results show that the flexible switching controller can make the terminal voltage vectors of the two busbars quickly reach the same, and realize the non-circulating current switching operation without circulating current.

Intelligent Diagnosis Algorithm of Generator Stator and Rotor Based on VGG Network

LI Cheng,LIU Hao,JIANG Xifeng,WU Junfa,HAN Wengang,GAO Jianguo

Electronic Science and Technology. 2021, 34(11):  62-66.  doi:10.16180/j.cnki.issn1007-7820.2021.11.010

Abstract ( 215 )   HTML ( 7 )   PDF (1331KB) ( 31 )  

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In view of the problem that the potential defects of generator stator and rotor seriously affect the safety and stability of unit operation, an intelligent diagnosis algorithm of generator stator and rotor based on VGG network is proposed. Compared with Alex network, VGG network uses multiple stacked small size convolution filters instead of large size convolution filters, which reduces the size of algorithm parameters and deepens the depth of network structure. The proposed algorithm includes two parts: offline training and online monitoring. The former part uses the local server generator stator and rotor historical images for learning and training to obtain the VGG network model which meets the accuracy requirements. The latter part uses the trained VGG network model to realize the online real-time monitoring of generator stator and rotor. The simulation results show that compared with the Alex network, the proposed algorithm has faster convergence speed, smaller calculation error and higher recognition accuracy for generator stator and rotor defects.

Improved Current Prediction Deadbeat Control Method for Active Power Filter

REN Lei,FU Ziyi,LEI Haixun

Electronic Science and Technology. 2021, 34(11):  67-74.  doi:10.16180/j.cnki.issn1007-7820.2021.11.011

Abstract ( 386 )   HTML ( 6 )   PDF (1028KB) ( 48 )  

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In view of the delay and inductance deviation coefficient problem in the process of deadbeat control, an improved current prediction deadbeat control method for active power filter is proposed. This method uses Lagrangian second-order polynomial interpolation method combined with repeated control to predict the reference current, which improves the accuracy of reference current prediction. Moreover, the compensation current calculation formula is constructed and the weight coefficient which can also reduce the influence of inductance parameter deviations on system stability is introduced to reduce the influence of current ripple. The value principle of the weight coefficient is given by the system stability analysis. MATLAB simulation results show that after filtering by this method, the grid-side current distortion rate is reduced to 3.38%, which indicates that the proposed method can effectively improve the waveform quality and reduce the influence of the inductance parameter deviation on the control performance.

Control Parameter Optimization of Cascaded H-Bridge Power Electronic Transformer

GAO Shang,YAO Lei,LI Yang,LI Ruixin

Electronic Science and Technology. 2021, 34(11):  75-80.  doi:10.16180/j.cnki.issn1007-7820.2021.11.012

Abstract ( 363 )   HTML ( 6 )   PDF (727KB) ( 42 )  

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As an important part of distributed energy, PET has received widespread attention. Due to the existence of nonlinear components, the harmonic content of PET network side current is relatively high. In this study, CHB-PET based on the PR control is the research object, and the double closed-loop control strategy of voltage outer loop and current inner loop is adopted to optimize the parameters of CHB-PET. The simulation results show that changing the proportional coefficient and resonance coefficient of the PR controller will also change the harmonic content of the grid-side current. When the proportional coefficient remains unchanged and the resonance coefficient changes from 1 000 to 100, the harmonic content of the grid side decreases from 3.24% to 3.20%. Similarly, when the resonance coefficient remains unchanged and the proportional coefficient changes from 50 to 25, the harmonic content of grid side current decreases from 3.20% to 2.54%. The results show that compared with the resonance coefficient, the proportional coefficient is more sensitive to the harmonic content of the grid-side current.

Magnetic Field Analysis of Magnetic Bearing Pole Fault under Fault-Tolerant Control

WANG Jialiang,JIANG Kejian,ZHU Fangfu

Electronic Science and Technology. 2021, 34(11):  81-87.  doi:10.16180/j.cnki.issn1007-7820.2021.11.013

Abstract ( 239 )   HTML ( 4 )   PDF (2807KB) ( 28 )  

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When an AMB has a magnetic pole failure under fault-tolerant control, the magnetic coupling between the magnetic poles and the nonlinearity of the electromagnetic force make it impossible to generate the required electromagnetic force on the magnetic pole surface, which will has a greater impact on the suspension of the rotor. To solve this problem, in this study, finite element software is used to simulate and analyze the magnetic field distribution of the AMB with strong coupling and weak coupling structure when single and two magnetic pole failures occur, and the influence of these two structures on the suspension of the rotor is compared and analyzed from the perspective of the magnetic field. In view of the fact that there is more magnetic flux leakage in the gap between the two magnetic poles of 8-pole radial AMB, the AMB generally can only control the magnetic flux on the magnetic poles, the magnetic flux density of the air gap between the rotors is simulated and analyzed. The simulation results show that the current utilization rate of the 12-pole AMB exceeds 99%, which effectively reduces the magnetic flux leakage.

Study on Six Pulse Double Variable AC-AC Frequency Converter with Step Frequency, Voltage and Speed Regulation

ZHOU Jiuling,MENG Juanjuan,LI Yudong

Electronic Science and Technology. 2021, 34(11):  88-94.  doi:10.16180/j.cnki.issn1007-7820.2021.11.014

Abstract ( 221 )   HTML ( 5 )   PDF (2193KB) ( 33 )  

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In the six pulse dual variable cycloconverter, there are some problems such as weak anti-interference ability and narrow speed range in the intermediate frequency band.Based on six pulse dual variable frequency conversion, the control strategy of frequency conversion combined with closed-loop voltage regulation in medium frequency band is proposed. After the frequency conversion, this method changes the output voltage through closed-loop control to control the speed. Subsequently, a MATLAB simulation model is built, and the trigger pulse is controlled by S-function, the control effect of the combination of frequency conversion and closed-loop voltage regulation are verified in the case of motor speed and torque mutation. The MATLAB simulation results show that the control strategy cannot only reduce the memory space of the system and improve the running speed, but also increase the speed range of the medium frequency band and the robustness of the motor.