Table of Content

10 August 2021, Volume 32 Issue 15

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Review on Development of Legged Robots for Deep Space Landing Exploration#br#

SUN Junkai, SUN Zezhou, XIN Pengfei, LIU Bin, WEI Qingqing, YAN Chuliang

2021, 32(15):  1765-1775.  DOI: 10.3969/j.issn.1004-132X.2021.15.001

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The research status of deep space landing exploration legged robots was introduced in the major aerospace powers， such as the United States， Europe and China. Moreover， advantages and disadvantages of legged robots for deep space landing exploration were analyzed， and the issues that caused the legged robots not to be used in engineering yet were discussed from the hardware and software design aspects. Then, the key technologies of legged robots for deep space landing exploration were proposed， including sensory fusion technology， intelligent control technology， reconfigurable structure technology and multi-robot cooperation technology， which offer references for the development of legged robots that may be actually applied in the deep space landing exploration. 

G-KSVD Dictionary and Its Applications in Sparse Representation of Rolling Bearing Fault Signals#br#

MENG Zong, GAO Wenqing, PAN Zuozhou, ZHANG Guangya, FAN Fengjie

2021, 32(15):  1776-1785.  DOI: 10.3969/j.issn.1004-132X.2021.15.002

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For the lack of atomic coherence analysis and the lack of optimal atomic selection in the learning dictionary， a G-KSVD dictionary learning methods was proposed based on effective singular components herein. The method comprised the following steps. First， the ACFPER was proposed based on the coherence of the signals. The singular component was screened to achieve the signal denoising and the updating of the dictionary atom, and the solution of the coefficient were realized by using a component containing more fault information. Thus， the purpose of enhancing the impact components in the signals was achieved. Then the algorithm reduced the feedback layers in order to cut down the time cost. Last， the validity and repeatability of the proposed method were verified by using the simulation signals and the actual bearing signals. The results show that the G-KSVD algorithm has good denoising effectiveness in the idoneity interval， furthermore the time cost is low. 

Study on Fuzzy Self-tuning MRPID Control Method in Rotating Speed Control of BLDCM#br#

TANG Wei, WANG Lizhong, ZHUANG Jian, WANG Tingkai

2021, 32(15):  1786-1792,1800.  DOI: 10.3969/j.issn.1004-132X.2021.15.003

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It was very difficult to reduce the influences of uncertain factors such as high-frequency signals like sensor noise and low-frequency signals like commands and interferences in a closed-loop control system of BLDCM speeds. And these led to fluctuation of rotating speeds. So a fuzzy self-tuning wavelet MRPID control method was proposed to solve this problem. The errors of rotational speeds were decomposed into layers including high frequency, intermediate frequency and low frequency components by discrete wavelet transform(DWT). Then the gain of each component was adjusted by fuzzy controller. At last, the performance of the proposed fuzzy self-tuning MRPID controller was evaluated in both of simulation and experiments under different dynamic operating conditions as taking the traditional PID controller as a comparison. The capabilily of processing noisy signals as well as fast response and good robustness of the proposed fuzzy self-tuning MRPID controller was verified by the results of simulation and experiments. 

Feature Extraction of Rolling Bearings Based on WAEEMD and MSB

GUO Junchao, ZHEN Dong, MENG Zhaozong, SHI Zhanqun, GU Fengshou

2021, 32(15):  1793-1800.  DOI: 10.3969/j.issn.1004-132X.2021.15.004

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Aiming at the facts that the modulation signal bispectrum(MSB) might only process stationary signals, a novel method for fault feature extraction of rolling bearings was proposed based on the WAEEMD and MSB. Firstly, vibration signals of rolling bearings were decomposed into a list of intrinsic mode functions(IMFs) by ensemble empirical mode decomposition(EEMD). Subsequently, the IMFs were reconstructed into the WAEEMD filtered signals using the weighted average method based on Teager energy kurtosis (TEK). Finally, the MSB was used to decompose the modulated components in the WAEEMD filtered signals and extract the fault characteristic frequencies. The analysis results illustrate that the WAEEMD-MSB has a superior performance over fast kurtogram (FK) and EEMD-MSB in extracting bearing fault features.

Test Study on Output Flow Pulsations of Conjugated Straight-line Internal Gear Pumps#br#

CHEN Zongbin, HE Lin, LIAO Jian,

2021, 32(15):  1801-1811.  DOI: 10.3969/j.issn.1004-132X.2021.15.005

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To better understand the pulsation characteristics of the conjugated straight-line internal gear pumps output flows, the secondary source method was deduced, the error parameters which might be introduced from each stages were analyzed, and the effects of each parameter on the accuracies of test results were also evaluated. Then, the calculation methods of impedance fitting and flow pulsation were derived in detail, and the visual data processing software was compiled. Finally, a test platform was built to test the output flow pulsations of the pumps. Compared with theoretical values, the test results show that the flow pulsation data processing method is accurate and feasible. The output flow pulsations of conjugated straight-line internal gear pumps are dominated by first-order line spectrum, and decrease first and then increase with the increases of rotation speeds.

Optimal Design of Contact Probes for Three-dimensional Thread Measuring Machines#br#

YANG Yanling, YU Jing, LIN Ximeng, CAI Jinhui

2021, 32(15):  1812-1817.  DOI: 10.3969/j.issn.1004-132X.2021.15.006

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In order to reduce the influences of the contact probes on the accuracy of the high-precision three-dimensional thread measuring machines， an optimization plan for the structure and size of the contact probes was designed， and the corresponding calibration method was proposed. The structural parameters of the probes were optimized through finite element simulation and orthogonal experiments to determine the optimal structural parameters. The calibration model of the probes was established by the coordinate transformation theory and the principle of least square method and the calibration experiments were carried out. The optimized probes were tested through the screw plug gauge comparison experiments and the screw ring gauge and plug gauge comparison experiments under different preloads. The results show that the standard deviation of the parameters of the contact probe measuring thread plug gauge and ring gauge is about 1 μm， which meets the measurement accuracy requirements of the contact probes of the three-dimensional thread comprehensive measuring machines. The optimization scheme and calibration method provide important theoretical basis for the design of the probe structures. 

Structural Optimization of Downhole Hydrocyclones Based on Response Surface Methodology#br#

XING Lei, LI Jinyu, ZHAO Lixin, JIANG Minghu, HAN Guoxin,

2021, 32(15):  1818-1826.  DOI: 10.3969/j.issn.1004-132X.2021.15.007

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 Based on numerical simulation method and central composite design method， the mathematical models of the relationship among the structural parameters of downhole hydrocyclones and the separation efficiency and the underflow pressure loss were established by using the second-order polynomial function. Additional tests were carried out to compare the predicted values of the mathematical model with the actual ones of numerical simulation. The average relative errors between the predicted values and the actual ones of the separation efficiency and pressure loss are as 0.104% and 4.562% respectively， which verifies the accuracy of the prediction results of the model. Meanwhile， a comparative study was carried out on the separation performance between the response surface optimization structure and the initial structure. The results show that when the inlet oil droplet size varies in the range of 50～500 μm， the initial structural separation efficiency ranges from 58.92% to 98.56%. After optimization， the separation efficiency ranges from 60.35% to 99.48%. When the inlet water content changes in the range of 94%～99%， the separation efficiency of initial hydrocyclones increases from 74.61% to 88.07%， after optimization the separation efficiency is in the range of 75.26%～91.56%. Under the conditions of different inlet oil droplet size and water content， the optimized structure shows obvious high efficiency and applicability.

Research on Splash Lubrication Characteristics of Two-stage Gearboxes Based on MPS Method#br#

XIE Chixin, LIU Huanlong, JIA Ruihe, LI Qiang

2021, 32(15):  1827-1835,1843.  DOI: 10.3969/j.issn.1004-132X.2021.15.008

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During splash lubrication, the distribution of the lubricant flow field inside the secondary transmission gearbox was very complicated. The traditional finite element method was difficult to perform visual simulation analysis. Based on sufficient research and a large number of preliminary calculations, the MPS method was proposed to study the splash lubrication characteristics of the secondary transmission gearbox for rail vehicles. The flow field characteristics of the gearboxes under different input shaft speeds, initial lubricating oil volumes and ambient temperature were analyzed, and the visual calculation of gearbox splash lubrication was realized. The time-domain variation of the number of oil particles at the gear meshing points was analyzed under different operating conditions, and it is found that the number of particles at the meshing points has little relationship with the speed, and was positively correlated with the initial oil volumes. The number of lubricating oil particles in the meshing area is the largest at 40 ℃ and the lubrication effectiveness is the best. The gear churning power losses of the gearbox under various operating conditions were analyzed, and it is found that the gear churning power losses are positively correlated with the input shaft speeds and the initial oil volumes, and negatively correlated with the ambient temperature increment, and both of the relationship is of nonlinear feature.

Differences of Injury Response among Hybrid Ⅲ Dummy，GHBMC Model and Chinese Human Body Model in Frontal Crash#br#

LI Hejun, YANG Zhen, ZHOU Dayong, ZHANG Haiyang, WANG Bo, ZHANG Jinhuan

2021, 32(15):  1836-1843.  DOI: 10.3969/j.issn.1004-132X.2021.15.009

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Based on the research results of the Automobile Crash Laboratory of Tsinghua University on the Chinese parametric human body model， the Chinese 50th-percentile human body model which might be used for crash simulation was generated according to the parameters of the Chinese 50th percentile human body. The crash simulations of different human body models are performed under the same working conditions， and the difference of the injury response of the Hybrid Ⅲ dummy， the GHBMC FE model and the Chinese 50th-percentile human body model were studied by using the injury response analysis and the injury risk curves. The results show that， compared to the Chinese 50th percentile human body model， the Hybrid Ⅲ 50th percentile dummy model has a higher risk of neck and chest injury， while the GHBMC 50th percentile human body has a lower risk of thigh injury. The analysis revealed the differences and limitations of the two evaluation tools in evaluating the driver restraint system designed based on the protection of the Chinese human body. 

Study on Influences of Layer Height on Forming Quality of Ceramic Slurry Microfluidic Extrusion#br#

ZHANG Jing, ZHOU Jing, ZHANG Xu, DUAN Guolin

2021, 32(15):  1844-1853,1860.  DOI: 10.3969/j.issn.1004-132X.2021.15.010

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In order to determine the optimal layer height and the maximum height of the ceramic slurry formed by micro-flow extrusion， the five height relations between the nozzle and the deposited filament  were analyzed after the filament flew out of the nozzle for zirconia ceramic slurry， the influence mechanism of the height of the nozzle on the printing quality was discussed， and the interlayer compression deformation model was established according to the slurry characteristics. The surface morphology， forming precision and mechanics properties of the printed samples were measured and characterized by digital microscope scanning， dimension measurement and mechanics test through 3D printing technology tests with different nozzle diameters and different layers， and the correctness of the model was verified. The results show that under the different ratios of the layer height to the nozzle diameter， the printing quality from good to bad is as follows：0.96， 0.92， 0.86， 1， 1.2. Therefore， a reasonable layer height setting may reduce the printing defects of ceramic parts， and improve the printing quality， which may provide some theoretical guidance for the selection of processing parameters based on material extrusion-based additive manufacturing. 

Microstructure and Thermal Shock Properties of CoCrAlSiY/YSZ Gradient Coatings by Double-powder-feeding Laser Cladding#br#

WANG Tao, ZHU Lei, TANG Jie, WANG Hao, WU Jun

2021, 32(15):  1854-1860.  DOI: 10.3969/j.issn.1004-132X.2021.15.011

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CoCrAlSiY/Y2O3-ZrO2（YSZ）gradient coatings were prepared on TC4 substrates by double-powder-feeding laser cladding. The microstructure， element distribution， microhardness and thermal shock properties of the CoCrAlSiY/YSZ gradient coatings were analyzed. The results show that the gradient coatings are firmly bonded to the substrates. There are no obvious interfaces between the gradient sublayers and cracks in the coatings， indicating that a good metallurgical bond is formed. The microhardness of the gradient coatings change progressively with the increase of YSZ contents. The thermal shock tests at 750 ℃ in different cycle periods show that the CoCrAlSiY/YSZ gradient coating have certain thermal shock resistance. 

Clinching Test for High Strength Steel-Aluminum Alloy Dissimilar Material Sheets#br#

LI Qihan, XU Chuanwei, GAO Song, HAN Xiaoheng, ZHAO Qingming, GU Dongwei, MA Fenglei

2021, 32(15):  1861-1867.  DOI: 10.3969/j.issn.1004-132X.2021.15.012

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The non-destructive connection between 6061-T6 aluminum alloy and HC340/590DP duplex steel with large performance differences was studied. The forming law of the steel-aluminum clinching processes and the connection quality under different joints were studied through tests. The qualities of the joints between the upper steel-lower aluminum and the upper aluminum-lower steel were studied respectively. The influences of forming forces on the joints quality were quantified by using the important processing parameters such as neck thickness， undercut and bottom thickness of the forming sections. The strength and energy absorption of clinched joints were studied by tensile shear tests. The results show the quality of clinched joints is good when the forming force is as 40 kN， and the strength and safety of the joints meet the requirements of design index. 

Study on Variation Laws of Inherent Strain of Q345/SUS304 Dissimilar Steel Welded Joints#br#

LI Yuantai, WU Huaxin, DONG Bin, XIAO Shenchong

2021, 32(15):  1868-1873.  DOI: 10.3969/j.issn.1004-132X.2021.15.013

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In order to predict the welding deformation of dissimilar steel structures quickly and accurately， a thermo-elastic-plastic finite element method was developed to simulate the residual stress and deformation of dissimilar steel welded joints. Based on this method， the inherent strain of Q345/SUS304 dissimilar steel plate butt joints and T-joints was studied. Furthermore， for complex Q345/SUS304 dissimilar steel welded structures， the inherent strain method and the traditional thermo-elastic-plastic finite element method were used to predict and compare the welding deformations. The results show that with the increase of the heat input parameter Q/h2， the tendon forces and transverse shrinkages increase approximately linearly， and the relationship among them and Q/h2 is obtained， while the angular deformations increase first and then decrease， which reach the peak value around Q/h2=12 J/mm3. The laws may provide references for prediction and control of welding deformations of large dissimilar steel structures in engineering. 

Multi-row Facility Layout Design Based on Random-key Bat Algorithm

DONG Shuhao, XU Zhigang, QIN Kaizhong, CHANG Yanru, SU Kaiyuan, ZHU Jianfeng

2021, 32(15):  1874-1883.  DOI: 10.3969/j.issn.1004-132X.2021.15.014

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Aiming at the multi-row facility layout problems with uncertain number and position of vertical passages in rows, a layout optimization model was established with the goals of minimizing logistics intensity, minimizing the no-load intensity of handling equipment and maximizing the interrelations between operation units, and a random-key BA was proposed for the model based on mapping rules. The idea of random-key coding was introduced into BA, and the mapping rules and steps from bat position based on random-key coding to combinatorial solution of multi-row facility layout were defined, so that the algorithm might be executed in continuous spaces without discretization, and the layout schemes with different code length might be mapped in combinatorial spaces. Finally, the proposed random-key BA was used to solve an example of multi-row facility layout problem, and the advantages of the algorithm were proved.

Design and Kinematic Analysis of Crawler-type Pipeline Endoscope Robots for Wind Turbine Blades#br#

ZHANG Yue, DONG Lei, HUAN Ronghua, HUANG Zhilong

2021, 32(15):  1884-1889.  DOI: 10.3969/j.issn.1004-132X.2021.15.015

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 Aiming at the environmental characteristics of the wind turbine blades including variable cross-sections， large slopes， and multiple obstacles， a crawler-type pipeline endoscope robot with a 4-DOF joint was designed for internal inspection and maintenance， and the kinematic characteristics of the proposed robot were analyzed herein. The robot included three parts：front/rear crawler-type mobile platform and a middle 4-DOF joint. The 4-DOF joint consisted of a 2-DOF cross joint commonly used in a snake robot， and forward/backward rotation module. Through the cooperation of the four motors inside， functional movements such as head-up， turning， multi-angle rolling and climbing might be realized. Firstly， the basic structure， dynamic system and connecting mechanism of the 4-DOF joint were introduced. Then， the forward and inverse kinematics of the robot were solved based on the D-H method. The working space of the robot was then obtained， and the overall dynamic simulation of the robot was carried out using CoppeliaSim. Finally， the robot was assembled according to the proposed design scheme， and the realization of various functional movements of the robot was verified through experiments.