Table of Content

25 October 2024, Volume 35 Issue 10

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Research Status and Development Trends of Large Wind Turbine Main Shaft Sliding Bearings

ZHU Caichao1, ZHANG Ronghua1, SONG Chaoshen1, TAN Jianjun1, YANG Liang2

2024, 35(10):  1711-1721.  DOI: 10.3969/j.issn.1004-132X.2024.10.001

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The pace of large wind turbine units was accelerating, and the reliability of core components was increasingly important for wind turbine operations. Sliding bearings had the advantages of high load capacity, long life, easy maintenance, scalability and small size, and they had advantages and great potential for the reliable replacement of wind turbine main bearings key components produced at home. The problems of main shaft rolling bearings in high-power wind turbines and the advantages of using sliding bearings on the main shaft were analyzed herein. The technical methods and application status of wind turbine main shaft sliding bearing design, materials, lubrication, and experimental verification were present in detail, and the existing problems of high-power wind turbine main shaft sliding bearings and future development trends were summarized. It is expected to provide reference for the digital design and industrial development of high-power wind turbine main bearings.

Research on Geometric Parameter Constraints of Swing Roller Movable Tooth Transmission Systems

WEI Rui1, JIN Herong1, 2, 3, YANG Zeyu1, CHEN Tao1, YI Yali1

2024, 35(10):  1722-1731,1739.  DOI: 10.3969/j.issn.1004-132X.2024.10.002

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Aiming at the problems such as long dimensional chain and weak structure of key components for the traditional swing movable tooth transmission, a new type of swing roller movable tooth transmission configuration and the tooth profile design method and parameter selection strategy were proposed. The swing roller movable tooth transmission mechanism was equivalent treated, and the equivalent connecting rod vector transfer model was constructed by topological analysis. According to the principle of conjugate meshing, the conjugate tooth profile vector equations of wave generator and ring gear were derived. Based on the constraint conditions of avoiding motion interference and top cutting of tooth profiles, the selection strategies of swing coefficient and base circle radius of the wave generator were developed with the transmission pressure angle as the evaluation basis. The tooth profile design and performance analysis were carried out according to the optimized parameters and the two groups of comparison parameters. The results show that the designed swing roller movable teeth transmissions have continuous tooth profiles and are able to run without stalling. Under the same load conditions, the peak value of engagement force of the wave generator and movable teeth with the optimized parameters is 37.09% and 28.28% lower than that of the comparison groups, which verifies the effectiveness of the design strategy. The research may provide theoretical reference for the tooth profile design and parameter selection of swing roller movable teeth transmission.

Design of Twisting Climbing Wheeled Inspection Robot for Mining Wire Ropes

TANG Chaoquan, TONG Binghang, TANG Wei, ZHANG Gang, WANG Siyuan, TANG Hongwei, LIU Bei, ZHOU Gongbo

2024, 35(10):  1732-1739.  DOI: 10.3969/j.issn.1004-132X.2024.10.003

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In response to the unmanned inspection requirements of mining wire ropes, a rope-twisting climbing inspection robot was designed and developed. Compared to traditional axial climbing robots, which required approximately 91.5% of the driving force. When carrying a load of 3 kg, the robot may overcome obstacles with a height 0.6 mm higher than that of axial climbing robots. With an obstacle height of 3 mm, the maximum load capacity exceeds that of axial climbing robots by 0.4 kg. Climbing experiments were conducted under simulated deep mine conditions with wire rope vibrations. The results show that the climbing robots exhibite stable climbing performance when the wire ropes are stationary, achieving a maximum climbing speed of 8.25 m/min and capable of continuous climbing for 500 m. Under low-frequency large-amplitude vibration conditions, the climbing speed of the robot is higher than that when stationary, while under high-frequency small-amplitude vibration conditions, slight fluctuations in climbing speed are observed due to wire rope vibrations.

Reseach on Improvement of Creeping Phenomenon of Sliding Guideways by Composite Lubrication Texture

FAN Yujie, CHEN Yuzhe, HAO Mengjie, WANG Suyang, DU Yuchen, XIA Jing, GUAN Xiaoyan

2024, 35(10):  1740-1746,1761.  DOI: 10.3969/j.issn.1004-132X.2024.10.004

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The creeping phenomenon of sliding guideways at low speed and heavy load seriously affected the machining accuracy of the machine tools. In order to improve the creeping phenomenon of the sliding guideways, the design of composite lubrication structure on the surfaces of sliding guideways and the characterization of friction force in stages were studied. The composite lubricating micro-texture was prepared by high temperature and high-pressure mosaic method based on the laser ablation micro-texture. The characterization methods of friction force in stages were proposed by friction tests. The influences of different composite lubricating structures on the friction characteristic parameters of each stage were explored. The theoretical models of the composite lubricating structures to improve the creeping phenomenon were established, and the composite lubricating structures with the best performance to suppress the creeping phenomenon were found. The results show that the surface micro-texture only affects the severe stick-slip and climb stages of friction force, while the composite lubrication texture has a significant effect on the entire start-up stage. The multi-stage composite lubrication texture(SF-3) with the combination of sinusoidal grooves and hexagonal pits filled with molybdenum disulfide (MoS2) was the most effective in improving the surface contact conditions and suppressing the creep phenomenon. Compared to the smooth surface(SS) sample, the creep time of the SF-3 sample is reduced by 72%, the instability force in the first stage is reduced by 69.83%, and the friction jump force in the second and third stages is reduced by 75.91% and 80.17%, respectively. 

Structure Optimization of Load Port Independent Double Spool Electro-hydraulic Valves

CHEN Junxiang1, 2, QI Fanyu1, JIANG Hongda1, 2, KONG Xiangdong1, 2, JIN Zhenlin1, AI Chao1, 2

2024, 35(10):  1747-1761.  DOI: 10.3969/j.issn.1004-132X.2024.10.005

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In order to study the influences of load port independent electro-hydraulic valve system parameters on the main valve fretting characteristics, a state space equation of electro-hydraulic valve systems was established based on the power bond graph theory, and the first-order sensitivity method was used to analyze the influences of system parameters on the main valve fretting characteristics. The pilot structure parameters of the feedback control systems were very important to the movement characteristics of the main valve, the dead zone width of the pilot stage, the form of the valve port and the matching coefficient of the inlet and return oil valve port were studied under the constraint conditions of no self-excited oscillation and the best damping ratio, the best match between the lead stage and the main stage was achieved. The results show that the main valve fretting characteristics are greatly affected by the friction force of the main valve core, the liquid capacity of the non-spring control chamber, the liquid capacity of the pipeline from the pilot valve inlet to the main valve control chamber(non-spring side) and the preload force of the main valve spring. While optimizing the above influencing parameters, the dead zone width of the pilot valve δ≤0.25 mm, the U-shaped valve port, and the matching coefficient of the inlet and return oil valve ports η=0.53, the overall performance of the system is effectively improved.

Experimental Investigation of Discharge Aided Grinding Dressing Method of Coarse-grained Diamond Wheels

DAI Longzhou1, MAO Cong1, ZHANG Mingjun1, CHEN Genyu2

2024, 35(10):  1762-1773.  DOI: 10.3969/j.issn.1004-132X.2024.10.006

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The problems of difficult to control the morphology of abrasive grains on coarse-grained diamond grinding wheels were presented. A discharge aided grinding dressing technology was proposed to achieve the uniformity of abrasive grains on the cutting edges. The material removal mechanism of this hybrid dressing was systematically analyzed. The numerical models of pulse discharge heat transfer were established, and the thermal softening depth of diamond was used as the grinding depth, which was conducive to the advantages of the hybrid dressing method. The influences of machine tool kinematic parameters (such as the speed of the grinding wheel, the speed of the tool wheel, the feed speed, and the grinding depth) on the grinding wheel dressing accuracy and the loss depth of tool wheel in the discharge aided grinding dressing method were investigated, and the processing parameters were optimized to achieve high efficiency and precision dressing of coarse-grained grinding wheels. The profile error PV value of the diamond grinding wheels with a grain size of 180# is as 11.97 μm. The inspection results of the surface morphology of the dressing wheel indicate that discharge powered grinding may partially remove the abrasive particles, resulting in good homogeneity of the abrasive particles on the surfaces of the grinding wheel. The surface roughness of the ground silicon carbide ceramic workpiece reaches 412 nm, indicating that the dressing wheel has excellent grinding performance. 

Study on Performance and Optimal Design of Friction Pairs of Textured Disk

XU Ping, LUO Jing, YU Yinghua, SHEN Jiaxing, LI Wenli

2024, 35(10):  1774-1782.  DOI: 10.3969/j.issn.1004-132X.2024.10.007

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In order to explore an effective way to improve the anti-friction and wear resistance of the disc friction pairs, the port plates of the swash plate piston pump were taken as the research object. Under the same conditions of area texture ratio and section depth shape, the variation of friction coefficient of the port plates machined elliptical and circular opening discrete pit micro-texture and grooved micro-texture with morphology, rotation speed, and pressure were studied by simulation and experiments comprehensively. The results show that the friction coefficient decreases significantly with the increase of rotational speed and decreases with the increase of pressure, the elliptical opening discrete pit micro-texture is the best among the three micro-textures to improve the performances of port plates. The multi-objective parameter optimization of elliptical opening discrete pit micro-texture was carried out, and the optimal parameters are obtained as follows: the radius of the long axis of the ellipse opening is as 452 μm, the short half axis is as 187 μm, and the radial center distance is as 0.7 mm. The experiments verify that the optimized textures friction coefficient and wear amount are reduced to different degrees under different working conditions compared with that before optimization. 

Design and Research of Variable Instantaneous Center Exoskeletons Driven by Pneumatic Artificial Muscles

LI Chaoyang1, LUO Tianhong2, MA Xiangyu2, FANG Shangchen1, WANG Ke3

2024, 35(10):  1783-1792.  DOI: 10.3969/j.issn.1004-132X.2024.10.008

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Aiming at the problems of low matching between the existing lower limb exoskeleton structure and the body, a new variable instantaneous center artificial knee joint driven by pneumatic artificial muscles was proposed by introducing additional degrees of freedom on the existing anti-quadrilateral joints. Combined with the kinematics analyses of the variable instantaneous center exoskeleton, the instantaneous center trajectory equations were solved, and the particle swarm algorithm was used to optimize the design of the knee joint structures. At the same time, the PID controller was used to simulate and analyze the motions, and experimental research was carried out. The results show that the instantaneous center trajectory of the proposed new variable instantaneous center artificial knee joints has a better match with the ideal instantaneoust center trajectory of the human joints, which provides reference and empirical support for the optimal design of the human-machine compatible structures.

Tool Wear Condition Monitoring for Drilling CFRP/TC4 Laminated Materials Using scSE Optimised ResNet-50

NIE Peng1, YANG Chengyue1, PENG Xinyue1, YU Jiahe2, PAN Wujiu1

2024, 35(10):  1793-1801.  DOI: 10.3969/j.issn.1004-132X.2024.10.009

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Aiming at the problems of severe tool wear in the preparation of assembly holes for laminated materials consisting of carbon fibre reinforced composites and titanium alloys, a tool wear monitoring method with scSE optimised deep residual neural network(ResNet-50) was proposed. Drilling experiments were carried out to collect force and temperature signals during the drilling processes. The signals were converted to wavelet scale spectrum using continuous wavelet transform. The ResNet-50 network structure was built to calibrate the weights of the convolutionally extracted feature maps from both spatial and channel dimensions. The results show that scSE may enhance the useful features and suppress the useless features from both spatial and channel dimensions, and the recognition accuracy of the network structure optimised by scSE reaches 96.15%.

Incorporating Simplification and Solution Strategies of Multi-conflict Network in TRIZ and Extenics

XU Chenhui1, 2, ZHANG Jianhui1, 2, GUO Xiangdong1, 2 , DING Zhaoqi1, 2, ZHANG Shun1, 2

2024, 35(10):  1802-1814.  DOI: 10.3969/j.issn.1004-132X.2024.10.010

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In order to solve the problems of high functional complexity of product systems and tedious conflict solving processes, the strategies for simplifying and solving multi-conflict networks were investigated herein. Firstly, the conflicts were described by using the extensible basic element models, and a multi-conflict network was constructed by using the causal analysis methods based on functional models. In order to identify key conflicts the techniques for order preference by similarity to ideal solution（TOPSIS）methods were applied to establish a comprehensive evaluation system from the perspectives of the topological characteristics of conflicts in the network and the degree of customer requirements. Secondly, a method for decomposing key sub-conflict networks was proposed to extract conflicts related to key conflicts and form sub-conflict networks. Finally, a set of rules for simplifying multi-conflict networks was proposed, which utilized extensible transformations to eliminate the relationships between conflicts. The simplified sub-conflict networks were then integrated, and the TRIZ tool was used to solve the key conflicts, so as to put forward a strategy for simplifying and solving multi-conflict networks. The feasibility and effectiveness of this strategy were demonstrated through the analysis of an intelligent stair-climbing wheelchair as an example.

Design and Test Analysis of Flexible Joint Elastic Components

LI Qi, GAO Hong

2024, 35(10):  1815-1823,1844.  DOI: 10.3969/j.issn.1004-132X.2024.10.011

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A method for designing elastic components for flexible joints was designed, the design concept and design approach of the cross spring sheet-type elastic components was proposed. Firstly, the structure composition of the flexible joints was planned, the mechanics models of elastic components were established based on beam constraint conditions and constitutive relationships, the specific items of the flexibility matrix and stiffness matrix were determined, and the dynamics modeling of the motion end of the flexible joints was performed simultaneously. Next, instances of the elastic components was designed, and the design was validated through finite element analysis, the modal frequencies and mode displacement of the flexible joints during motion were simulated. Finally, an experimental system was set up to test the designed instances of the elastic components, and the rotational stiffness was calculated. Through cross-validation and analysis of three sets of data samples, the results show good consistency between the theoretical, simulated, and experimental values of the designed elastic components, with a maximum error of 7.59% in the first set, 4.32% in the second set, and 6.70% in the third set. This indicats the feasibility of designed elastic components using beam constraint theory and constitutive relationships. The proposed elastic joint elastic components are versatile and may be applied to articulated robotic arms and to rehabilitation robots and bionic robots, providing a new approach to the design of flexible joints for robots.

Holistic Topology and Parameter Lightweight Design of Composite Tailgate Structures

CHENG Aiguo1, WANG Chao1, LU Rijin2, HE Zhicheng1, YU Wanyuan3

2024, 35(10):  1824-1833.  DOI: 10.3969/j.issn.1004-132X.2024.10.012

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A holistic topology and parameter lightweight design method for the tailgate of a new energy vehicle was proposed by combining injection-molded long glass fiber-reinforced(LGF) polymer composite. The co-simulation models and conventional simulation models were established for the performance simulation and optimization design of the tailgates respectively, to improve simulation accuracy and optimization efficiency. Firstly, the composite tailgate structures were optimized and redesigned by three steps structural conceptal design based on conventional simulation models. Secondly, co-simulation models were established for subsequent multi-objective optimization and verified by sample production and performance tests. Finally, the elitist non-dominated sorting genetic algorithms (NSGA-Ⅱ) were used to optimize the rib thicknesses, key position thicknesses, and cross-sectional dimensions of the tailgates in detail. The mass of optimized composite tailgates is reduced by 27.2% compared to original steel tailgates, and the torsional stiffness, transverse stiffness, bending stiffness, and free mode of the tailgates meet the application requirements.

Optimization Decision of CFRP Processing Parameters Considering Cutting Energy Consumption and Surface Quality

YAN Wei1, 3, WANG Xinyi2, 3, ZHANG Hua3, ZHU Shuo2, 3, JIANG Zhigang2, 3

2024, 35(10):  1834-1844.  DOI: 10.3969/j.issn.1004-132X.2024.10.013

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The factors affecting secondary processing energy consumption and quality of CFRP were more complex than those of traditional materials, which made the existing empirical formulas difficult to apply. Taking the cutting force analysis of CFRP secondary machining as the starting point, the optimization decision problems of CFRP processing parameters were studied by considering energy consumption and quality. Firstly, the effects of fiber angle on CFRP processing form were analyzed, and the cutting force models were derived. Secondly, a multi-objective optimization model was established with three cutting elements and fiber direction angle as variables and cutting energy consumption and surface roughness as objectives. A multi-mutation driven particle swarm optimization(DM-PSO) and AHP integrated processing parameter optimization decision-making method was proposed. Finally, the feasibility and superiority of the above models and methods were verified by the milling experimental design.

Low Carbon and High Quality Modeling and Processing Parameter Optimization of CNC Milling Machines

LI Zeya1, LUO Min1, ZHANG Chaoyong2, XU Jinyu1

2024, 35(10):  1845-1851.  DOI: 10.3969/j.issn.1004-132X.2024.10.014

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 Aiming at the problems of high carbon emission efficiency and poor surface quality caused by using unreasonable processing parameters during the working processes of CNC milling machines, an optimization method of CNC milling machine processing parameters oriented to low carbon and high quality was proposed. Initially, carbon emission factors in the milling processes were analyzed, and target functions of carbon emission efficiency, surface roughness, and processing time were defined. Prediction models for carbon emission efficiency and surface roughness for CNC milling machines were subsequently established, utilizing the support vector regression improved by grey wolf optimizer. Then, with spindle speed, feed rate, and cutting width designated as optimization variables, an improved egret swarm optimization algorithm was applied to optimize the cutting parameters. This resulted in obtaining Pareto front solutions for processing parameters that were low in carbon emissions, high in quality and efficient. Suitable processing parameters were selected using the EW-TOPSIS method. Finally, an experimental platform for monitoring carbon emissions in CNC milling machines was established, and the feasibility and validity of the proposed method were verified by the experimental results.

Surface Creation Mechanism Analysis of Machining SiCp/Al Based on Strain Gradient Theory

FAN Yihang, CHU Xingyu, HAO Zhaopeng

2024, 35(10):  1852-1861.  DOI: 10.3969/j.issn.1004-132X.2024.10.015

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In order to gain a deeper understanding of the cutting processes of particle reinforced aluminum matrix composites, a constitutive model was established based on the strain gradient theory for 45%-SiCp/Al composites through multiphase modeling. Through the secondary development of simulation software ABAQUS, the established constitutive equation and B-W fracture criterion describing fracture were programmed into the user subroutine VUMAT using programming language, and then imported into ABAQUS for simulation analysis. Based on the cutting experiments and simulation analysis results, the changes in surface temperature, internal stress and strain, and dislocations of SiCp/Al composite materials with different cutting depths at the same cutting speed were studied. The results indicate that the modified constitutive model is more consistent with the experimental ones compared to the traditional Johnson-Cook model, and it is found that an increase in cutting depth will trigger a high-temperature gradient. The internal stress of the material will form stress concentration near the particles. A large number of dislocations appear in areas with high strain on the machining surfaces, which increases the difficulty of machining particle reinforced metal matrix composites.

Mechanism Study of Shapings Influences on Accuracy of Roll Forming Products

XING Gang1, HAN Fei1, HUANG Hongjiang2

2024, 35(10):  1862-1870.  DOI: 10.3969/j.issn.1004-132X.2024.10.016

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In order to study the shapings influences on the accuracy of roll forming products, experiments and the finite element method were used to analyze different shaping schemes influences on the accuracy of products. The forming force, torque, stress and strain were analyzed in the roll forming processes of different shaping schemes, to reveal the shapings influences on the accuracy of roll forming products. The results show that the shaping may reduce the residual stress of the plates, and reduce the influences of the end flare effect on the accuracy of the formed parts. The influences on springback increase with the increase of the forming angle, which means the larger the angle is, the greater the influences of shaping. 

Determination on Internal Pressure Loading Path of Hydroforming with Axial-circumferential Feeding for Heavy Truck Axle Housings

ZHANG Jiaqi1, 2, WANG Liandong1.2, WANG Xiaodi2, SONG Xiliang2

2024, 35(10):  1871-1880,1889.  DOI: 10.3969/j.issn.1004-132X.2024.10.017

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 The deformation processes of hydroforming with axial-circumferential feeding were complex, and it was difficult to determine a reasonable loading path. The tube was prone to instability wrinkling and cracking in forming. Based on the deformation analysis, the variation laws of internal pressure for the deformation at typical positions in two stages of the hydroforming with axial-circumferential feeding were revealed, the loading path of linear pressurization—constant pressure—linear depressurization were determined, the calculation formula of internal pressure in each stage was derived, and the relationship between the plane height of upper control die and the maximum diameter expansion was given. For an axle housing of 10 t heavy truck, the finite element simulation of hydroforming axial-circumferential feeding and the engineering tests were carried out, and the correctness of loading path was verified. The influences of the depressurization coefficient in the linear depressurization section of the loading path and the height coefficient of the upper control die on the forming quality of the tubes was revealed, and the reasonable ranges of both coefficient were determined. The risk of instability wrinkling and cracking is eliminated.

Data-driven Fatigue Load Spectrum Compiling of Concrete Pump Truck Booms#br#

LI Peng1, 2, 3, 4, WANG Yitang1, 4, WANG Jiaqian2, 3, ZHOU Peiquan2, 3, YANG Liangliang1, 4, SONG Xueguan1, 4, ZHENG Yuebin5, 6

2024, 35(10):  1881-1889.  DOI: 10.3969/j.issn.1004-132X.2024.10.018

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In order to analyze the fatigue of concrete pump trucks, a data-driven method of compiling fatigue load spectra for concrete pump truck booms was proposed by utilizing big data analysis technology. The typical operating posture of concrete pump trucks was defined by analyzing the angle of boom inclination and pinch angle. Then, load information was collected according to the selected typical operating posture, and data pre-processing was performed on the collected raw signals to improve the data quality and make the fatigue load spectrum more reliable afterwards. A parametric method was used to estimate and extrapolate the  amplitude distribution of the tested load spectra to obtain the load spectra under the whole life cycle, and the load spectra were strengthened for fatigue verification. The reliability and engineering practicability of the proposed method were verified by conducting tests on a large amount of data collected from 300 pump trucks of a certain model. The results provide some references for the fatigue load spectrum preparation of the multi-joint boom structure of concrete pump trucks. 

Blade Pitch Control of Wind Turbines with Speed Regulating Differential Mechanism Considering Impeller Imbalance

ZHANG Wenhua1, YIN Wenliang1, ZHANG Zhenbin2, LIU Lin3, PENG Ke1

2024, 35(10):  1890-1899.  DOI: 10.3969/j.issn.1004-132X.2024.10.019

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To ensure the energy efficiency and stability of the SRDM-based WTs across the entire wind speed ranges, a control method was proposed based on radial basis function（RBF) neural networks and sliding mode variable structure control（SMVSC), which enabled precise and rapid pitch angle adjustment for SRDM-based WTs, while considering the effects of wind wheel imbalance, wind shear, and tower shadow. This approach incorporated the sliding mode error into the adaptive law, allowing for the effective suppression of chatting effects by dynamically adjusting the weights and center values of the RBF neural network in real-time. A simulation model of 1.5 MW SRDM-based WTs was established, and then verified using the built experimental platform, through which the control performance of the proposed RBF-SMVSC method was compared and validated. The results indicate that, compared to independent pitch methods with traditional proportional-integral（PI) and SMC, the proposed control method may adjust WTs speed and power output more rapidly and accurately under various wind speed conditions, and significantly enhance energy capture and reduce unbalanced loads.