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    Volume 51,2023 Issue 21
    • End Vibration Suppression of Industrial Robot Based on Parametric Decoupled Notch Filter
      PAN Haihong; DING Keshuai; WU Xipeng; CHEN Lin; LIANG Xubin

      Abstract:The end vibration of 6-DOF industrial robot joints is caused by the insufficient stiffness of the transmission device,the traditional notch filter is usually used to solve this problem.However,the coupling between filter parameters makes it difficult to adjust filter parameters quickly.Therefore,a notch filter with parameter decoupling was designed based on the established double inertia load model of industrial robot.The transfer function of the traditional notch filter was analyzed,and the pole and zero cancellation method was used to decouple the notch filter parameters.The notch filter center frequency,width and depth were taken as the notch filter parameters directly.Finally,Fourier transform and logarithmic decay method were used to quickly adjust the parameters of the improved notch device,so as to suppress the end vibration of industrial robot.A 6-DOF experimental platform for industrial robots was built.The results show that there is no parameter coupling in the parameter decoupling notch filter,and the parameter adjusting is convenient;compared with no filter,the positioning vibration of industrial robots can be reduced by 78.5%, which proves that the improved parametric decoupled notch filter is feasible and effective in suppressing the positioning vibration.

    • Mechanical Analysis and Motion Simulation of Permanent Magnet Adsorption Crawler-Type Out-of-Pipe Crawling Robot
      JIANG Yiwei; HOU Yu; LI Haonan; SUN Wei

      Abstract:In order to improve the load capacity and obstacle ability of the out-pipe robot, a permanent magnet adsorption crawler-type out-of-pipe crawling robot was designed. The static and dynamic models of the robot on the pipe were established to obtain the adsorption force conditions for the robot in axial and circumferential stable motion. Ansoft Maxwell was used to compare and analyze two different layouts of permanent magnets in the magnetic track set, the appropriate layout was selected and the adsorption forces provided by the magnetic track set were calculated in axial and circumferential motion under the layout, and the rationality of the magnetic track set design was verified. Finally, the motion simulation of the robot was carried out based on ADAMS, and the change rule of the mass center during the obstacle crossing process was obtained, which verified the obstacle crossing performance of the robot.

    • CNN-LSTM Modeling and Estimating Method of Pneumatic Gripping Force for Robot
      DANG Xuanju; QIN Chuangye

      Abstract:Since the hysteresis and strong nonlinearity exist in the pneumatic system, it is difficult to achieve effective control of the pneumatic gripping force based on the air pressure signal directly, and using modeling to estimate the gripping force is an effective way to achieve low-cost control without force sensors. A convolutional neural network(CNN)-based optimized long short-term memory neural network (LSTM) was proposed for the low-cost pneumatic gripping force estimation method. According to the characteristic that the gripping force of the end pneumatic gripper of the industrial robot is related to historical inputs/outputs of the pneumatic circuit, a LSTM network with memory characteristics was used to build a sensorless pneumatic/gripping force estimation model. Aiming at the problem of large modeling error by using LSTM network directly, CNN was used to extract the nonlinear relationship of air pressure and gripping force in the input information to optimize the LSTM network structure, which could improve the ability of the model to describe the multi-valued correspondence/nonlinear hysteresis relationship between air pressure and gripping force, and achieve effective estimation of gripping force of pneumatic gripper. The experimental results show that compared with the LSTM prediction models, the root mean square error of the modeling estimation and validation estimation for the proposed model is reduced by 77.14% and 70.83%, and the maximum error is reduced by 79.80% and 78.84%, respectively, which proves the effectiveness of the proposed estimation method.

    • Transmission Characteristics Analysis and Design of Humanoid Robot Arm with Multi-motor Coupling Drive Mode
      DOU Rutong; YU Shenbo; ZHAI Fengchen; XIA Pengpeng; LI Wenyang; YOKOI Hiroshi; JIANG Yinlai

      Abstract:Aiming at the low ratio of load and deadweight for traditional humanoid manipulators,a humanoid robot arm with a multi-motor coupling drive mode was proposed.According to the motion characteristics of the human arm,the configuration of the humanoid robot arm with series structure was determined,and the robot arm was divided into the shoulder joint module,the elbow joint module,and the wrist joint module.The rope transmission characteristics of a single motor driving a single joint model were analyzed,and the torque mapping relationship and rotation angle mapping relationship between motor and joint of the model were derived.Moreover,the motor layout and winding mode of multi-motor coupling driving multi-joint were studied in each module,and the working principle of multi-motor coupling was explained.Meanwhile,the torque mapping relationship and rotation angle mapping relationship between motor and joint in each module were deduced.The correctness of the mapping relationship in each module and the bearing capacity of each module joints were verified by experiments.The results show that the multi-motor coupling driving mode can effectively improve the bearing capacity of each joint on the premise of ensuring weight,it also provides a theoretical basis for the design of a humanoid robot arm.

    • Configuration Design and Nonlinear Mechanical Properties Analysis of Tensegrity Robot
      LIU Ruiwei; LIN Xuntao; GUO Hongwei; WANG Chunlong; XIE Hao; TANG Zhenyu

      Abstract:The six-bar tensegrity is balanced by the internal force distribution between the cable and the bar,and has the characteristics of large displacement and strong nonlinearity,which has large application potential in the robot field of planetary exploration.To obtain the nonlinear mechanical properties of the structure,the mathematical analysis model of the six-bar tensegrity was constructed by the node matrices,adjacency matrices,and vector matrices.On this basis,considering the geometric nonlinearity of the structure,the mechanical analysis model was established,and the influence of different loads and structural parameters on the mechanical properties was analyzed.The deformation sensitivity of each parameter was calculated,and the effective method to improve the stiffness of the six-bar tensegrity was obtained.Finally,the six-bar tensegrity robot prototype was fabricated and the rolling over experiments were implemented.This conclusion can provide certain theoretical support for the follow-up structural optimization and kinematic control.

    • Design and Research of Multi-rotor 6-DOF Parallel Robot Based on Axial Motor
      CHEN Fei; CHEN Jilin; HOU Yuanlong

      Abstract:In order to expand the working space and reduce the overall size of the parallel robot, a multi-rotor 6-DOF parallel robot was designed, in which six SPS (S-sphercal hinge; P-prismalic pair) branch chains were used to connect the upper moving platform and sliding blocks on the fixed platform,the sliding blocks rotated around the fixed platform to change the position of the moving platform. The two coordinate systems of the moving platform and the fixed platform were established to obtain the inverse solution of the attitude of the 6-DOF parallel robot through the transformation matrix. After the attitude information of the parallel robot was obtained, each branch chain was regarded as a two-force rod and the force of each sliding block was obtained. Through the force of the sliding blocks, the important parameters of the drive design such as the torque power of the rotor of the parallel robot were obtained.The new parallel robot has the characteristics of unrestricted Z -axis rotation, greatly expanding its motion range, its structure sizes are greatly reduced compared with conventional parallel robots.

    • Kinematics Analysis and Path Planning of a Six Axis Transcranial Magnetic Manipulator
      JI Changwei; SHANG Huichao; HAN Xinlei; FU Xiaoli; LI Zhiqiang

      Abstract:At present, the treatment of transcranial magnetic therapy instrument is mainly manual, with large time intensity and high cost, which seriously restricts the development of domestic transcranial magnetic industry. For this reason, according to the size of GB 2428—1998“Head-face dimensions of adults”, an intelligent transcranial magnetic six axis mechanical arm was designed, which could replace manual hand-held work. It was characterized by high work intensity and flexible treatment schedule. SolidWorks 3D software was used for the overall modeling of the manipulator. Based on the improved D-H parameter method and the Robotics Toolbox toolbox in MATLAB software, the kinematics model of the manipulator was established, and the forward and inverse kinematics equations of the manipulator were derived and solved. Taking the six axis transcranial magnetic manipulator as the research object, a semi simulation test platform was built to carry out the Monte Carlo workspace simulation and path planning simulation. Bidirectional RRT algorithm was used to generate collision free path points, and polynomial interpolation function was used to fit the generated three treatment tracks. Finally, the curves of the whole path track and the angular displacement, angular velocity, angular acceleration and other relevant motion parameters of each joint with time were output. The results show that the six axis mechanical arm can meet the requirements of high precision, high efficiency, flexibility and smooth operation of transcranial magnetic therapy instrument.

    • Research on Multi-modal Motion Control and Optimization Method of Bionic Robot Ray
      CHEN Guojun; CHEN Wei; JIN Jun; WANG Zhiming

      Abstract:The ray uses the pectoral fin to swing and propel, which is characterized by high stability and strong concealment. A hybrid control method based on fuzzy control and central pattern generator (CPG), namely fuzzy-CPG algorithm, was proposed to control the motion of the bionic robot ray in the complex underwater environment. Based on the CPG control model, a high-level sensory feedback control mechanism was introduced, and the parameters of the CPG were adjusted by a fuzzy controller to achieve multi-mode motion control of the bionic robot ray. The performance of the bionic robot ray multi-modal motion under different initial parameters of the Fuzzy-CPG controller was analyzed through straight ahead swimming, in-situ turning and dynamic sinking and floating tests. The stability of the bionic robot ray swimming under various modes of motion was verified through the feedback of the posture sensor. The test results show that the Fuzzy-CPG motion control method can not only realize the multi-mode motion of the bionic robot ray, but also has good robustness.

    • Design and Kinematics Analysis of Low Coupling PRPaR-2CPR Parallel Robot
      XIA Ronghua; LIU Yanli

      Abstract:A new type of PRPaR-2CPR parallel robot mechanism with parallelogram branch chain was proposed.The mechanism was composed of one PRPaR branch chain and two CPRs.It had the characteristics of simple structure,low coupling and high stiffness.The topological design theory and method of parallel mechanism based on the POC equation were used to analyze and calculate the degree of freedom and kinematic properties.Kinematic equations were established using the constraint conditions of link length,and the inverse solution expression was obtained through calculation.At the same time,the positive numerical solution was obtained.In addition,according to the calculation and analysis,the existence conditions of singularity were obtained.Through the inverse solution expression of position,the limit boundary search method was used to obtain the performance maps of workspace and motion dexteri ty respectively,and the corresponding performance maps were drawn for analysis.Finally,it was expected to obtain better motion flexibility performance in the limited operating space.With the global dexterity in the task workspace as the optimization goal,genetic optimization algorithm (GA) was selected to optimize the structural parameters.The dexterity performance in the optimized task workspace has been greatly improved,so the motion performance of this kind of parallel mechanism is improved.

    • Research on Iterative Learning Control of 〖JP3〗VCM Force at the End of Robot Surface Polishing
      HUANG Haibin; FU Tingshuo; WANG Tongte; CHENG Huakang; ZOU Chaosheng

      Abstract:Aiming at the problem of compliance control and response speed in robot polishing of curved surface components, a set of compliance control system for robot polishing was studied. The slicing algorithm was used to complete the polishing trajectory planning to control the robot to comply with the low-frequency profile and curvature changes of the surface of curved components. A force controlled end effector was designed to meet the requirements of active force output and high-speed response. The current iterative optimization control strategy based on iterative learning control was proposed to make the output force of voice coil motor in the actuator follow the target force with high accuracy, reducing the waviness and surface roughness of the high-frequency segment of the surface of components. An experimental platform with robots, force control actuators, six dimensional force sensors and motion control cards as the core components was built. The simulation and experimental results show that the designed compliance control system has good force control performance, the average force response time is 55.4 ms, and the force tracking error is less than 3 N, which can meet the needs of surface component polishing.

    • Analysis on Joint Vibration Characteristics of Industrial Robot with Clearance Nonlinear
      YI Lingxiao; PAN Sining; LIU Zhicheng; LIU Yingzhong

      Abstract:Electromechanical coupling dynamic model of nonlinear joint with clearance was established in order to study the influence of joint clearance on vibration characteristics of industrial robot. By numerical analysis on stability of the system clearance, the torsional vibration characteristics simulation study of the joint’s key components was made. The clearance test bench was constructed to make clearance test for a single joint swing arm. A clearance compensation strategy based on torque observer was proposed on the basis of the collected current parameters. The accuracy of the joint model with clearance was verified via results of clearance test and simulation research of resonance frequency domain response of joint system. According to the test results of current signal before and after compensations, the compensation strategy can be used to improve stability of joint system.

    • Simulation Design of Robot Workstation for Water Tank Polishing Based on RobotStudio
      TANG Zhenyu; DAI Zhujian; TANG Lun; BI Qilin; XU Hu; DONG Shengtai

      Abstract:In order to solve the problem of automatic grinding of four side welds of stainless steel water tank,the robot end effector and other equipment were designed based on SolidWorks,and the simulation platform of water tank grinding robot workstation was built based on RobotStudio,which was composed of abrasive belt grinder,IRB4600 robot,end effector and other equipments.According to the actual working conditions of the stainless steel water tank,the polishing process flow and the polishing path were designed,the Smart components of the polishing workstation were created,and common I/O signals were associated.The TCP track tracking function and collision monitoring function were used to check whether each track point and motion track met the working requirements,and the timer was called to record the grinding time.In the simulation platform,the ideal grinding track can be obtained through offline programming,simulation and debugging,which can be used for actual operation,and is conducive to improve the on-site programming and processing efficiency,improve the weld grinding quality.

    • Sensorless Compliance Control of Manipulator Based on Expected Trajectory Modification
      ZHU Jinghua; SHAO Zhufeng

      Abstract:In order to improve the control accuracy of the contact force when the manipulator interacts with the environment, a sensorless active compliance control method based on expected trajectory correction was proposed. Aiming at the problems of traditional parameter identification methods, such as many saddle points of loss surface function, easy to fall into local optimization, and large calculation amount, based on Newton-Euler method, a recursive parameter identification method of manipulator from outside to inside was proposed, which could realize the step-by-step and batch identification of parameters. Aiming at the active compliance control problem when the manipulator interacts with the environment, the position impedance control principle was used to modify the desired trajectory, and the nonsingular terminal sliding mode control was designed under the condition of parameter uncertainty. Finally, the stability of the control system was proved based on Lyapunov theory. Through experimental verification, the cumulative absolute error of the back calculation torque based on the traditional identification method is 9.35 N·m, while it is 1.05 N·m based on the recursive identification method, which indicates that the accuracy of the parameter recursive identification is much higher than that of the traditional identification method. Under the control of position impedance , the contact force reaches the set value in 2.8 s, and the error fluctuation range is ±0.4 N.The experimental results verify the superiority of the active compliance control method.

    • Energy Consumption Prediction of Heavy-Duty CNC Gear Profile Milling Machine Tool Based on NC Program
      DING Wenzheng; HE Wenquan; ZHANG Jin; XING Bo; BIAN Rong

      Abstract:Accurately predicting the energy consumption of heavy-duty CNC gear profile milling machine tools is the theoretical basis of energy saving and consumption reduction in the manufacturing process.Therefore,taking the heavy-duty CNC high-speed gear milling machine as the research object,an energy consumption prediction method based on NC program was proposed.The energy consumption characteristics of the energy consuming components of CNC machine tools were analyzed,and the components were classified according to the energy consumption characteristics.The energy consumption model of each component was established,and the calculation method of material removal rate of gear forming milling was proposed.Finally,a gear energy consumption prediction program was developed.Moreover,experiments on two different types of heavy-duty CNC gear profile milling machines show that the prediction accuracy of the method is more than 95%,and the method is feasible.In addition,the feed speed was increased by 10% respectively on the two high-speed gear milling machines in the experiment,the energy savings are 7.52% and 4.25% respectively.The results show that the larger size of the heavy machine tool is,the greater the energy saving potential is.

    • Mechanism Design and Analysis of a New Type of Four-Freedom Parallel Vibration Isolation System
      LI Yajing; YUE Yi; WEI Baochen; CUI Guohua; LIU Guoxing

      Abstract:In order to avoid the patients in the ambulance suffering from the secondary injury caused by the vibration of the car body,a new type of 2-UPS-2-(RP-RR) U symmetrical parallel vibration isolation device was proposed based on the screw theory and full Jacobian singularity analysis.The mechanism has two rotational degrees of freedom and two mobile degrees of freedom (2R2T).Based on the screw theory and the relationship between the rigid body axis and the constraint screw,two continuous axes of the moving platform were determined.One of the axes was a fixed axis,which was independent of the configuration of the mechanism and passed through the origin of the static coordinate system and along the Y axis;the other axis was arbitrary,which was related to the configuration of the mechanism.The motion continuity of the mechanism was verified by the two U pairs of center points of the moving platform.The closed-loop vector method was used to establish the inverse kinematics model of the mechanism,combined with the boundary search method,the workspace of the mechanism was simulated in MATLAB,the correctness of the motion model was verified.

    • Experimental Study on Micro-milling of Ti-48Al-2Cr-2Nb Alloy
      MA Xuan; WANG Zhiyong; DONG Hao; MA Xinxin; DU Jinjin

      Abstract:The new high-quality γ-TiAl based alloy Ti-48Al-2Cr-2Nb with low density, high specific strength and good high temperature mechanical properties has a broad application prospect in aerospace and precision micro parts manufacturing field. In order to study the micro-milling performance of the material, a four-factor and five-level orthogonal experiment was carried out by using a double-edged cemented carbide micro-milling cutter with a diameter of 0.8 mm. The effects of spindle speed, feed speed, milling depth and milling cutter spiral angle on the burr and roughness of micro-milling were studied. The results show that the spindle speed and milling depth are important factors affecting the top burr, and the influence of the milling cutter spiral angle on the groove bottom surface roughness is the most obvious. The results provide a theoretical basis for the micro-scale milling of γ-TiAl based alloy.

    • An Approach for EMG Based Prediction of Multi-joints Continuous Motion for Human Lower Limb
      HAN Yonglin; TAO Qing; ZHANG Xiaodong; CHEN Qingzheng

      Abstract:In order to capture the motion state of human lower limb joints under different motion modes in real time,a method of continuous motion prediction of lower limb joints using electromyography (EMG) was proposed.The EMG and motion data of human body in squat motion,knee flexion and extension motion and up and down stairs motion were collected and analyzed,and the simulation model of human skeleton and muscle was established by using musculoskeletal geometric modeling software Opensim,the inverse kinematics analysis was carried out to extract the movement curve of human lower limb joints.The mapping relation between the motion of human lower limbs in sagittal plane and EMG was established,and the sparrow search algorithm was used to optimize the Elman neural network to predict the continuous changes of ankle,knee and hip joint angles,the prediction results were compared with those of traditional back propagation neural network,support vector machine regression and Elman neural network.The results show that Elman neural network optimized by sparrow search algorithm has higher accuracy in predicting the change of lower limb joint angle;moreover,the predicted value and measured value of joint motion of the prediction model show certain correlation under different motion modes,and the correlation coefficient is greater than 0.89.It is proved that it is feasible to use EMG signal to predict the continuous motion of multiple joints of lower limbs.

    • Analysis of Sawing Vibration Characteristics of Circular Saw Blades for Wrought Aluminum Alloy Extruded Profiles for Architecture
      LU Laixia; JIAO Shourong; YAN Yuqin; ZHU Yanming; QIN Meizhen; SUN Jie

      Abstract:During the cutting process of circular saw blades for wrought aluminum alloy extruded profiles for architecture,the vibration and noise of the profile due to the periodic impact of the circular saw blade seriously affect the processing efficiency and quality.A single-factor cutting experiment of aluminum alloy profiles with circular saw blade was designed to study the vibration characteristics at different feed rates.The results of time domain analysis show that the vibration signal has obvious subsection characteristics with the change of sawing position,and the difference between the peak vibration acceleration at different sawing stages is generally more than three times of the minimum value,which indicates that some typical structure has a significant impact on the vibration,such as the transverse flange structure.Through the frequency domain analysis,there is no multiple relationship between the peak frequency of sawing vibration and the rotation frequency,indicating that the rotation frequency is not the main factor affecting the vibration of the sawing process for aluminum alloy profiles.Moreover,with the increase of feed speed,the vibration energy gradually transfers from low frequency to high frequency.With the increase of feed speed from 25.0 mm/s to 75.0 mm/s,the maximum value of vibration acceleration in the feed direction gradually increased from 1 669.91 m/s2 to 2 001.59 m/s2,increasing by 19.86%.While,in the vertical feed direction,it is gradually increased from 932.52 m/s2 to 1 097.30 m/s2,increasing by 17.67%.The results show that the various structures in the wrought aluminum alloy extruded profiles for architecture have a much greater effect on sawing vibration than the effect produced by the feed speed.

    • Overall Design of Intelligent Inspection Production Line for Nuclear Power High Strength Steel Bar Connecting Sleeve
      ZHANG Jiayu; YANG Jiajun; YANG Shuo; NIU Huli

      Abstract:In view of the problems of high labor intensity, low production efficiency, and inability to meet the market demand, the quality inspection of high-strength steel bar connecting sleeves in nuclear power is currently completed manually, an intelligent inspection production line for high-strength steel bar connecting sleeves in nuclear power was designed based on the common steel bar connecting sleeves in the market. According to the modular design concept, the overall design scheme of the intelligent inspection production line for steel connecting sleeve was formulated, and the 3D modeling research for each section of the production line was carried out, and the prototype was debugged. The inspection production line realizes the integrated inspection of the structural size, thread profile, pitch, pitch diameter, major diameter and minor diameter of internal thread of the 32 mm steel bar connecting sleeve, with an efficiency of 8 pieces/min, which is about 10 times higher than the traditional manual method. The structure of the production line is reasonable. On the premise of ensuring the inspection quality, the inspection efficiency is greatly improved.

    • Real-Time Monitoring Method of Band Sawing Machine Status Based on Digital Twins
      CHEN Suifan; ZHU Zhenyao

      Abstract:Aiming at the problems of unstable running state and poor real-time monitoring effect of the traditional metal band sawing machine during processing, combined with digital twin technology, a real-time monitoring method of metal band sawing machine based on digital twin was proposed. A digital twin interconnected virtual entities and physical entities was built. A real-time monitoring system framework for the operating status of the band sawing machine was constructed based on the digital twin 5D model. After obtaining the actual operating data of the sawing machine, TWINCAT was used to simulate the PLC operation, and the data communication was carried out through the TCP/IP communication protocol of the XML file. Real-time data transmission was completed, and finally the data were uploaded to the MySQL database for storage. Thirdly, a scene roaming function that supported real-time 3D monitoring of the operating state of the sawing machine was developed, and a historical reproduction function that supported reappearing the historical operating state of the sawing machine was developed by querying historical operating data. Finally, the test verifies the real-time performance and effectiveness of the system.The results show that this system has good real-time performance and interaction.

    • Design and Manufacture of a High-Speed Rolling-Sliding Composite Guide Rail Pair
      ZHOU Meng; GUO Xin

      Abstract:The commonly used guide rail forms of CNC machine tools were analyzed. A rolling-sliding composite guide rail pair taking into account high-speed performance of linear guide rails and high rigidity of steel guide rails was proposed. The structural design and prototype test were completed, and the process methods in the manufacturing process were elaborated. The results of the prototype accuracy and rigidity test show that the high-speed rolling-sliding composite guide rail pair can meet the needs of precision, rigidity and moving speed for moving parts of CNC machine tools at the same time.

    • Optimization of Ejector Structure Parameters Based on EBF Neural Network
      YAO Dasuo; ZHAO Kaifang; WU Guopeng; JI Ning; PEI Yiqiang

      Abstract:In order to improve the performance of hydrogen fuel cell ejector,the hydrogen fuel cell ejector under rated operating conditions was taken as the research object,an optimization method of ejector structure parameters based on EBF neural network model and NLPQL algorithm was proposed.Based on orthogonal test,the EBF neural network model was established,the nonlinear relationship between the structural parameters of the ejector and the ejection coefficient was described. The precision of the proxy model was verified by comparing the simulated value of the ejection coefficient with the predicted value of the proxy model and the complex correlation coefficient. The NLPQL algorithm was applied to make global optimization, and the structure parameter combination with the maximum ejection coefficient was obtained and verified by simulation.The results indicate that,based on EBF neural network and NLPQL algorithm, the ejection coefficient of fuel cell ejector is improved,compared with the maximum value of the orthogonal test scheme, the ejection coefficient is increased by 3.9%.The method based on orthogonal test and EBF neural network can expand the research scope and level of ejector structural parameters,save the time of CFD simulation calculation.

    • Research on Four-Axis Machining of Shaft Part Based on Three-Axis Code Conversion of Expanded Contour
      WEN Hao; HUANG Dong; ZOU Weiquan; ZHANG Xiaoming

      Abstract:When generate the four-axis NC machining code for the complex expanded contour of the outer cylindrical surface, there are problems of instability, time-consuming and low efficiency.Based on the shaft part which outer cylindrical surface has complex expanded contour, the method of converting the three-axis code of the expanded contour to the four-axis code was studied. Based on the structure and motion control mechanism of the four-axis CNC machine tool, the operation method of NC code generation for the outer cylindrical surface with complex expanded contour in UG software was analyzed.The data conversion relationship between the tool position coordinates of the three-axis NC code from the complex expanded contour and the four-axis NC code was researched, and a four-axis code conversion software for the shaft part with the cylindrical surface was developed. Through the specific operation of UG and the developed code conversion software, the four-axis NC machining code of the shaft part with the outer cylindrical surface of the complex expanded contour could be generated and simulated in Vericut software. The test result shows that this proposed method can be used to directly realize the four-axis NC code generation for the shaft part with the outer cylindrical surface of the complex expanded contour, and the stability and speed efficiency are verified.

    • Research on the Combined Energy Recovery Method of Electric Forklift Based on Working Characteristics
      YANG Heng; LI Yan; DONG Qing; GUO Wenxiao; WANG Zhen

      Abstract:Aiming at the throttling loss and energy waste caused by frequent lifting and braking of gantry system and driving system of electric forklift in its working cycle, a combined energy recovery method based on working characteristics was proposed. On the basis of analyzing the typical working process of forklift, a combined recovery scheme of potential energy and braking energy of electric forklift with super capacitor as energy storage device was proposed, and the fuzzy PID adaptive control method was introduced to realize the accurate control of the displacement of hydraulic cylinder by the electro-hydraulic position servo system; aiming at the proposed scheme and control method, the simulation model of potential energy and kinetic energy joint recovery of electric forklift was established by using AMESim and Simulink software. Finally, the proposed method and simulation model were used to analyze the energy recovery of a working cycle of an electric forklift truck in a warehouse. The results show that the proposed method has a significant effect on the combined recovery of potential energy and brake energy, the range and energy efficiency of the electric forklift truck are improved.

    • Influence of Distributing Valve Structure Characteristics on Flow Output Characteristics of Micro High Pressure Piston Pump
      LIU Yucong; CAO Wenbin; YANG Guolai; MAO Yueying; ZHAO Tianhao; FANG Ruiqing

      Abstract:In order to meet the high power density requirements of aviation pumps,valve flow distribution is adopted to effectively reduce leakage and improve volume efficiency of micro high pressure piston pump.Aiming at the main factors affecting the flow output characteristics of micro high pressure piston pump,the mathematical model of micro high pressure piston pump with valve distribution was established,and flow distribution models of check valves with different structures were built by AMESim.The modeling and simulation experiments of ball valve,cone valve,plate valve and other check spool valve forms with different combination structures were carried out.The influence factors such as micro-pump clearance volume,swash plate angle,load pressure,check valve spring stiffness and spool mass were simulated and analyzed.The results show that the valve combination form is the best when the inlet valve and the discharge valve are both plate valves under the existing structure;the micro-pump volume efficiency is stable under variable speed condition,and the spool mass has little influence on the distribution valve hysteresis;increasing the swash plate angle or decreasing the load pressure and the clearance volume can effectively improve the valve opening lag angle,and then improve the volume efficiency.

    • Energy Consumption Analysis of Mining Ship Heave Compensation System Based on AMESim
      TENG Yuanyuan; HU Zhouguo; SONG Yu; CHEN Linkai

      Abstract:Since the heave motion generated by surge has a huge negative impact on the operation of the mining vessel,a heave compensation system is needed to ensure the safety and stability of the mining vessels operation.Heave compensation system can be divided into passive,active and active-passive types.The active-passive type is a combination of active and passive modules.To deal with the shortcomings of passive compensation accuracy is not high and the energy consumption of active compensation system is too large,a set of active-passive heave compensation system was designed.The 2 MN active-passive heave compensation model was built by using AMESim software,which was combined with the relevant experiments to prove that the simulation model was credible.Then the energy consumption and power of the active module of the active-passive heave compensation system were simulated under different loads,different wave periods and different wave amplitudes.The results show that the average contribution ratio of the active compensation module power is about 20%,and the passive compensation module bears about 80%,which reflects the energy-saving nature of the active-passive heave compensation system.

    • Study on the Influence of Axial Feeding on the Liquid Impact Forming of Double Metal Thin-Walled Tubes
      SUN Changying; LIU Jianwei; LI Yuhan

      Abstract:Liquid impact forming(LIF)of double thin-walled tubes is a compound forming technology developed on the basis of tube hydroforming (THF) and stamping forming. In order to obtain better forming quality, based on the combination of hydraulic pre-forming and liquid impact forming, double thin-walled tubes forming was realized by changing the loading path of hydraulic pre-forming. The liquid impact forming principle of double thin-walled tubes and the axial feeding scheme of inner tube were introduced. The influence of axial feeding distance on the thickness distribution of double thin-walled tubes was analyzed by Dynaform finite element method, and the influence law of axial feeding distance on the formability of double thin-walled tubes was obtained.At the same time, the influence of the axial feeding distance of the inner tube on the diagonal length of the tube section was analyzed, and the influence of the axial feeding distance of the inner tube on the filling property of the double thin-walled tube was obtained. Through the study of the loading path in the hydraulic pre-forming stage, the influence of axial feeding on the forming law of double thin-walled tubes is explored, which provides theoretical and application support for the forming of double thin-walled tubes under the impact hydraulic load.

    • Electromagnetic Characteristic Analysis of Asymmetrical V-Shaped Interior Permanent Magnet Synchronous Motor
      JING Jianning; SHI Liwei; LI Facheng; LIU Zhengwei; WANG Wenqiang

      Abstract:The asymmetrical magnetic pole interior permanent magnet synchronous motors (PMSM) can effectively reduce the cogging torque and torque ripple without reducing the electromagnetic torque,widen the speed regulation range.At the same time,the motor structure is reliable and the manufacturing difficulty is low,which has a wide potential application prospect in the fields with high torque performance requirements.A new mathematical model of asymmetric magnetic pole PMSM was established in order to investigate the changes of the electromagnetic characteristics of the motor caused by the magnetic field deflection of the rotor,and the electromagnetic performance of the PMSM with different magnetic pole structures were analyzed by finite element analysis method.The simulation results show that the asymmetric magnetic pole structure can effectively reduce the torque ripple and cogging torque of the interior PMSM; the forward shift of the magnetic pole has a wider constant-power range under the maximum torque per ampere control strategy.Finally,the realization methods in practical engineering applications of the control strategy for the asymmetric magnetic pole PMSM were given.

    • Optimal Design of Topology Structure of Multi-way Valve Core Throttle Groove
      FU Songsong; LI Weimin

      Abstract:Aiming at the problem that the operation force of the multi-way directional valve of the excavator is too large due to the steady-state flow force in the opening process, the visualization research of multiple physical fields of thermal-fluid- solid was carried out on the throttle groove of the valve core based on ANSYS. By analyzing the flow state under the valve core of the semi- circular throttle groove, the topology structure of the new throttle groove was proposed. A Non-Parametric Regression response surface model was established to study the influence of the new throttle groove structure size on steady-state flow force and mass flow rate. Combined with a multi-objective genetic algorithm, the flow state and steady-state flow force of the valve core before and after optimization were compared and analyzed. The results show that the new groove structure can reduce the steady-state flow force and effectively improve the reversing performance of the multi-way valve during the opening.

    • Analysis of Axial-Symmetric Vectoring Exhaust Nozzles Nozzle Accuracy Based on ADAMS
      DANG Pengfei; WANG Yu; YANG Zhengxin

      Abstract:In order to study the influence of error on nozzle accuracy,the axial-symmetric vectoring exhaust nozzle was taken as the research object,and the parametric point function of ADAMS software was used to build the model and simulate to verify the validity of the model.The indexes of the measurement functions of deflection angle,azimuth angle and nozzle area were established to measure the accuracy of the nozzle.Based on the design research function,the sensitivity of single design variable error on nozzle accuracy was obtained.ADAMS/Insight module and Monte Carlo method were used to complete the analysis of random design variable error of parts with a faster speed and less workload.The results show that the deflection angle relative error of the simulation value and the mean is 0.675%,azimuth angle is 0.847%,and nozzle area is 0.048%,the variation of nozzle accuracy is small,and the working range of the engine can be guaranteed when the random error is -0.1 mm<μ<0.1 mm.

    • Adaptive Optimization Method of Milling Parameters Based on Tool Life Level
      XU Fengli; SHAO Shujun; DU Chao; ZHANG Fuqiang

      Abstract:In order to solve the problem that the traditional optimization parameters cannot be dynamically adjusted with the change of tool life in the milling process,resulting in the inability of the tool performance to be fully utilized,an adaptive optimization method of milling parameters was studied,and a dynamic milling parameter multi-objective optimization method based on the optimization gray wolf algorithm was proposed.The nonlinear mapping relationship between the milling parameters and the optimization target in the milling process was constructed by BP neural network;then the concept of tool life level was proposed,and the milling parameters within the life level were adaptively optimized by the particle swarm optimization gray wolf algorithm.The experimental results show that the method can provide the optimal milling parameter scheme during the entire tool life cycle according to the life decay degree of the tool,and carbon emissions is reduced while the use value of the tool is improved.

    • A Review of Adsorption Methods for Wall-Climbing Robots
      YANG Huixuan; LIU Rong; HE Jiandong; AN Haiming; BAI Weiwei

      Abstract:The rapid development of science and technology and the application requirements of wall-climbing robots have made wall-climbing robots attract widespread attention. Adsorption method, as a key technical module for stable adsorption, agile movement and load-lifting of wall-climbing robots, is crucial for improving the overall performance of wall-climbing robots,at the same time, improvements in adsorption methods can further promote the miniaturization and lightweight of wall-climbing robots. The existing adsorption methods of wall-climbing robots were analyzed and summarized. The key technologies of the adsorption methods of wall-climbing robots were proposed and analyzed, including the trade-off between adsorption mode and movement mode, customized design of key components, optimal design supported by theoretical analysis and simulation analysis, the new materials development and simplified preparation process. An outlook on the development trend of miniaturization, light weight and large load of the adsorption methods of wall-climbing robots was made.

    • IPMSM Demagnetization Fault Model Predictive MTPA Fault Tolerant Control Based on Improved STO
      JIANG Mingkang; HAO Wanjun; LIU Yifan

      Abstract:Aiming at the problem that the system model and parameters change when the demagnetization fault occurs in the interior permanent magnet synchronous motor, and the control performance of the controller declines seriously, a demagnetization fault model predictive MTPA fault-tolerant control strategy based on the improved STO was proposed.Considering the demagnetization fault of the motor, the change of model parameters was analyzed, the fault model was rebuilt, and the MTPA curve considering the fault state was solved. Then, aiming at the sensitivity of model predictive control to parameter changes, an improved STO observer was constructed to identify the permanent magnet flux on-line. Finally, a current model predictive controller was designed to fault-tolerant control IPMSM with demagnetization fault. Through experimental comparison, the constructed observer has better observation performance for permanent magnet flux linkage in the case of demagnetization fault, and the fault-tolerant control strategy is also better.

    • Gearbox Fault Diagnosis Based on SVMD and Adaptive MOMEDA
      YUE Zihao; PEI Bang; LI Zhiyuan; WANG Zhengbing; HUANG Xiaodan; LEI Huanhuan

      Abstract:Due to the influence of background noise and transmission path, fault signals are often submerged, and fault features are difficult to extract. Therefore, a fault diagnosis method combining SVMD and adaptive MOMEDA was proposed. The reconstructed signal was obtained by SVMD preprocessing, and then the optimal parameters of MOMEDA were adaptively selected by artificial fish swarm optimization algorithm with the average spectral negative entropy as the adaptation function. The obtained parameters were used to carry out MOMEDA filtering on the reconstructed signal. Finally, the envelope spectrum analysis was carried out to diagnose the fault type. By applying the proposed method to the simulation signal and experimental signal of the broken tooth fault of the gearbox active wheel, the pinion rotation frequency and its multiplication can be clearly distinguished in the envelope spectrum, and the proposed method has better performance effect than other methods.

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