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RSS2019 Vol. 38, No. 6
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2019, 38(6): 821-827.
doi: 10.13433/j.cnki.1003-8728.20180247
PDF 1039KB
Abstract:
Environment temperature changes may easily cause damage misinformation of electromechanical impedance method (EMI) based on structural health monitoring. The influence of the temperature on the admittance signal experiment and the detection of bolt looseness damage under changing temperature condition were conducted respectively on an aluminum plate connected with bolt group. The mean absolute percentage deviation and correlation coefficient deviation metric were used to quantitatively describe the degree of admittance signal change. The iterative algorithm based on the signal cross-correlation was used to compensate the temperature effects in narrow frequency bands. The results show that the changing temperature causes the horizontal deviation of the admittance signal, and the offset increases with the frequency and temperature difference, causing the change of damage index and misinformation of bolt connection status. After compensation, the temperature effect are reduced significantly, and the sensitivity of the detection of bolt looseness damage is improved effectively so that the damage misinformation caused by changing temperature can be avoided.
Environment temperature changes may easily cause damage misinformation of electromechanical impedance method (EMI) based on structural health monitoring. The influence of the temperature on the admittance signal experiment and the detection of bolt looseness damage under changing temperature condition were conducted respectively on an aluminum plate connected with bolt group. The mean absolute percentage deviation and correlation coefficient deviation metric were used to quantitatively describe the degree of admittance signal change. The iterative algorithm based on the signal cross-correlation was used to compensate the temperature effects in narrow frequency bands. The results show that the changing temperature causes the horizontal deviation of the admittance signal, and the offset increases with the frequency and temperature difference, causing the change of damage index and misinformation of bolt connection status. After compensation, the temperature effect are reduced significantly, and the sensitivity of the detection of bolt looseness damage is improved effectively so that the damage misinformation caused by changing temperature can be avoided.
2019, 38(6): 828-832.
doi: 10.13433/j.cnki.1003-8728.20180258
Abstract:
This paper presents the implementation of a modified Canfield mechanism. Revolute joints are used as active joints instead of prismatic joints, and 3 torsion springs eliminate the singularities caused by the revolute joints. This arrangement is adopted for its usefulness in reducing the size of the structure, improving elongation/contraction restrictions and easily realizing full hemisphere movement. Based on the geometric symmetrical motion of the mechanism around the mid plane, a computationally simple kinematic solution is proposed. The proposed solution reduces not only the unknown numbers of the kinematics calculations but also the singularities in the workspace. The mechanism was implemented on a 3D printed plastic model which has an inertial measurement unit (IMU) mounted on the end-effector. The actuation was provided by a DC motor, and the feedback of the motor and the mechanism was acquired by an optical encoder and the IMU respectively. The simulation results obtained with the MapleSIM and the MATLAB are evaluated experimentally and the comparison results show that the mathematical model agrees with the experimental results.
This paper presents the implementation of a modified Canfield mechanism. Revolute joints are used as active joints instead of prismatic joints, and 3 torsion springs eliminate the singularities caused by the revolute joints. This arrangement is adopted for its usefulness in reducing the size of the structure, improving elongation/contraction restrictions and easily realizing full hemisphere movement. Based on the geometric symmetrical motion of the mechanism around the mid plane, a computationally simple kinematic solution is proposed. The proposed solution reduces not only the unknown numbers of the kinematics calculations but also the singularities in the workspace. The mechanism was implemented on a 3D printed plastic model which has an inertial measurement unit (IMU) mounted on the end-effector. The actuation was provided by a DC motor, and the feedback of the motor and the mechanism was acquired by an optical encoder and the IMU respectively. The simulation results obtained with the MapleSIM and the MATLAB are evaluated experimentally and the comparison results show that the mathematical model agrees with the experimental results.
2019, 38(6): 833-838.
doi: 10.13433/j.cnki.1003-8728.20180266
Abstract:
Aiming at the random vibration of vehicles with uncertain system parameters under random excitations, random vibration response of a quarter vehicle model is analyzed based on the pseudo-excitation and rapid perturbation method. The pseudo-excitation method is used to transform the random excitation into a simple harmonic excitation, and the expression of power spectral density of the vehicle vibration response is derived. Then, the variation coefficient of the vehicle body acceleration response is calculated based on the fast perturbation method. The numerical example of vibration analysis shows that when variation coefficient of the body structure parameters and the tire stiffness are 0.1, the variation coefficient of the vehicle body acceleration is up to 18.81%. Compared with the Monte Carlo method, it shows that computational efficiency is improved greatly with the methods of this paper, and the error is less than 5%.
Aiming at the random vibration of vehicles with uncertain system parameters under random excitations, random vibration response of a quarter vehicle model is analyzed based on the pseudo-excitation and rapid perturbation method. The pseudo-excitation method is used to transform the random excitation into a simple harmonic excitation, and the expression of power spectral density of the vehicle vibration response is derived. Then, the variation coefficient of the vehicle body acceleration response is calculated based on the fast perturbation method. The numerical example of vibration analysis shows that when variation coefficient of the body structure parameters and the tire stiffness are 0.1, the variation coefficient of the vehicle body acceleration is up to 18.81%. Compared with the Monte Carlo method, it shows that computational efficiency is improved greatly with the methods of this paper, and the error is less than 5%.
2019, 38(6): 839-845.
doi: 10.13433/j.cnki.1003-8728.20180253
Abstract:
A method for improving the point to point (PTP) acceleration of a selective compliance assembly robot arm (SCARA) manipulator is designed to eliminate the mechanical damage to the reducer due to the unlimited torque when the manipulator operates at a high speed. Instead of the Coulomb and viscous friction model, we propose an improved friction model to better represent the high-speed friction and identify the improved dynamic parameters of the SCARA manipulator by using the excitation trajectory and the least squares method. Furthermore, the identified dynamic parameters are used to predict the driving torque of the PTP acceleration of the SCARA manipulator and to implement the optimization algorithm with the well-chosen to obtain the optimal acceleration. Simulation and experimental results show that the improved dynamic model has a better torque prediction accuracy and higher computational efficiency of 8 ms on average, thus ensuring the real-time control. Above all, the optimal acceleration accomplishes a high efficiency with low torque from 112.2 N·m to 84.19 N·m of the multi-point PTP acceleration, which effectively extends the life span of the reducer.
A method for improving the point to point (PTP) acceleration of a selective compliance assembly robot arm (SCARA) manipulator is designed to eliminate the mechanical damage to the reducer due to the unlimited torque when the manipulator operates at a high speed. Instead of the Coulomb and viscous friction model, we propose an improved friction model to better represent the high-speed friction and identify the improved dynamic parameters of the SCARA manipulator by using the excitation trajectory and the least squares method. Furthermore, the identified dynamic parameters are used to predict the driving torque of the PTP acceleration of the SCARA manipulator and to implement the optimization algorithm with the well-chosen to obtain the optimal acceleration. Simulation and experimental results show that the improved dynamic model has a better torque prediction accuracy and higher computational efficiency of 8 ms on average, thus ensuring the real-time control. Above all, the optimal acceleration accomplishes a high efficiency with low torque from 112.2 N·m to 84.19 N·m of the multi-point PTP acceleration, which effectively extends the life span of the reducer.
2019, 38(6): 846-854.
doi: 10.13433/j.cnki.1003-8728.20180250
Abstract:
Check valve is a key component of the reciprocating high-pressure diaphragm pump. Regarding check valve fault vibration signal is often subjected to strong noise; it is difficult to detect the fault feature. A novel method to diagnosis the fault of check valve using empirical mode decomposition (EMD) and auxiliary correlation coefficient singular value decomposition (SVD) is proposed in this paper. Firstly, the check valve vibration signal is decomposed by empirical mode decomposition, then the intrinsic mode function (IMF) obtained by decomposition are used to reconstructed. Secondly, the reconstructed signal enters into the correlation coefficient SVD system for secondary decomposition and the component signals containing fault characteristic information are screened out by correlation coefficient method. Finally, the effective component signal is analyzed by Hilbert envelope spectrum analysis to diagnose the faulty of check valve. The simulation results show that the proposed method solved the problem of fault feature extraction under strong noise background, and the data measured indicates that the method can effectively detect the fault of the check valve.
Check valve is a key component of the reciprocating high-pressure diaphragm pump. Regarding check valve fault vibration signal is often subjected to strong noise; it is difficult to detect the fault feature. A novel method to diagnosis the fault of check valve using empirical mode decomposition (EMD) and auxiliary correlation coefficient singular value decomposition (SVD) is proposed in this paper. Firstly, the check valve vibration signal is decomposed by empirical mode decomposition, then the intrinsic mode function (IMF) obtained by decomposition are used to reconstructed. Secondly, the reconstructed signal enters into the correlation coefficient SVD system for secondary decomposition and the component signals containing fault characteristic information are screened out by correlation coefficient method. Finally, the effective component signal is analyzed by Hilbert envelope spectrum analysis to diagnose the faulty of check valve. The simulation results show that the proposed method solved the problem of fault feature extraction under strong noise background, and the data measured indicates that the method can effectively detect the fault of the check valve.
2019, 38(6): 855-862.
doi: 10.13433/j.cnki.1003-8728.20180255
Abstract:
A vibratory sorter was designed for the separation of polar groups in the recycling pretreatment process of used lead-acid batteries, and the ellipsoid basis function(EBF)neural network approximation model and particle swarm optimization(PSO)algorithm were used to optimized structural parameters of the vibratory sorter. Firstly, to reduce the mass, reduce the stress and increase the third-order natural frequency, the sensitivity analysis is done to obtain the structural parameters with the highest degree of influence. Secondly, the optimal approximation model of the experimental design sample is constructed by using EBF neural networks with the highest fitting degree, and PSO algorithm with better optimization effect is adopted for numerical optimization. Finally, the reliability analysis was performed on the structures before and after the optimization. The results show that the quality of the optimized values is reduced by 9.7%, the maximum equivalent stress is reduced by 36.7%, the third-order natural frequency is increased by 12.9%, and the structural reliability is increased by 5.9%.
A vibratory sorter was designed for the separation of polar groups in the recycling pretreatment process of used lead-acid batteries, and the ellipsoid basis function(EBF)neural network approximation model and particle swarm optimization(PSO)algorithm were used to optimized structural parameters of the vibratory sorter. Firstly, to reduce the mass, reduce the stress and increase the third-order natural frequency, the sensitivity analysis is done to obtain the structural parameters with the highest degree of influence. Secondly, the optimal approximation model of the experimental design sample is constructed by using EBF neural networks with the highest fitting degree, and PSO algorithm with better optimization effect is adopted for numerical optimization. Finally, the reliability analysis was performed on the structures before and after the optimization. The results show that the quality of the optimized values is reduced by 9.7%, the maximum equivalent stress is reduced by 36.7%, the third-order natural frequency is increased by 12.9%, and the structural reliability is increased by 5.9%.
2019, 38(6): 863-869.
doi: 10.13433/j.cnki.1003-8728.20180249
Abstract:
How to obtain a more accurate temperature distribution of regenerator has been a hot issue in the research of solar energy dish Stirling engine. In this paper, the momentum equation and energy equation of porous media based on non-local heat balance theory are established. With numerical analysis method, this paper discusses the influence law of the length of regenerator, layered wire mesh, inlet velocity, filling medium porosity, gas laser material, and the number of wire mesh on the temperature field distribution of the Stirling engine regenerator. The results show that the metal screen porosity and gas flow rate for wire mesh have a greater influence on the heat transfer performance of the regenerator. The appropriate extension of the length of regenerator can effectively improve the heat transfer performance of the regenerator.
How to obtain a more accurate temperature distribution of regenerator has been a hot issue in the research of solar energy dish Stirling engine. In this paper, the momentum equation and energy equation of porous media based on non-local heat balance theory are established. With numerical analysis method, this paper discusses the influence law of the length of regenerator, layered wire mesh, inlet velocity, filling medium porosity, gas laser material, and the number of wire mesh on the temperature field distribution of the Stirling engine regenerator. The results show that the metal screen porosity and gas flow rate for wire mesh have a greater influence on the heat transfer performance of the regenerator. The appropriate extension of the length of regenerator can effectively improve the heat transfer performance of the regenerator.
2019, 38(6): 870-876.
doi: 10.13433/j.cnki.1003-8728.20180246
Abstract:
For the purpose of simplicity and practicality, taking the dual in-wheel motors electric vehicle as the research object, based on the traditional Ackermann steering model, an improved Ackerman steering model based on the tire slip rate is proposed in this paper. Through the Matlab/Simulink modeling tool, the electronic differential model was constructed at first. Based on the model, the tire speed, the corresponding slip ratio and yaw rate of the dual in-wheel motors were simulated and analyzed. Then the ideal yaw rate obtained from the ideal two degree of freedom linear vehicle dynamic model further perfects the improved Ackerman steering model. Finally, the corresponding data curves are obtained through vehicle testing experiments, and the comparison of the simulation and test results showed that the proposed differential control model has been effectively implemented.
For the purpose of simplicity and practicality, taking the dual in-wheel motors electric vehicle as the research object, based on the traditional Ackermann steering model, an improved Ackerman steering model based on the tire slip rate is proposed in this paper. Through the Matlab/Simulink modeling tool, the electronic differential model was constructed at first. Based on the model, the tire speed, the corresponding slip ratio and yaw rate of the dual in-wheel motors were simulated and analyzed. Then the ideal yaw rate obtained from the ideal two degree of freedom linear vehicle dynamic model further perfects the improved Ackerman steering model. Finally, the corresponding data curves are obtained through vehicle testing experiments, and the comparison of the simulation and test results showed that the proposed differential control model has been effectively implemented.
2019, 38(6): 877-883.
doi: 10.13433/j.cnki.1003-8728.20180262
Abstract:
In order to verify the influence of different engine correction parameters on the calculation of the carbon load of the Gasoline Particulate Filters (GPF) by the engine electronic control unit (ECU), the control strategy of the gasoline engine particle trap under China Ⅵ emission standard is optimized and improved. Based on GPF's soot loading mass flow model, this model is modeled by Simulink, and the GPF precision carbon load calculation simulation model is built. The engine's original mass flow rate, air-fuel ratio correction parameters of the engine under different working conditions, PM filter efficiency correction parameters, the engine operating water temperature correction parameter and the engine load correction parameter calculation module were used to simulate the GPF carbon load. And by carrying a self-developed 1.5T in-cylinder direct injection engine for bench and vehicle road test, the accuracy of the accurate carbon load model of the direct-injection gasoline engine particle trap is verified. By weighing the GPF carrier, the effect of various modified parameters of the engine on the calculation of the model carbon load can be analyzed. By optimizing the models, the simulation results are closer to the vehicle performance. The research results are beneficial to realize the GPF offline calibration function, improve the GPF control strategy, and reduce the corresponding development cost.
In order to verify the influence of different engine correction parameters on the calculation of the carbon load of the Gasoline Particulate Filters (GPF) by the engine electronic control unit (ECU), the control strategy of the gasoline engine particle trap under China Ⅵ emission standard is optimized and improved. Based on GPF's soot loading mass flow model, this model is modeled by Simulink, and the GPF precision carbon load calculation simulation model is built. The engine's original mass flow rate, air-fuel ratio correction parameters of the engine under different working conditions, PM filter efficiency correction parameters, the engine operating water temperature correction parameter and the engine load correction parameter calculation module were used to simulate the GPF carbon load. And by carrying a self-developed 1.5T in-cylinder direct injection engine for bench and vehicle road test, the accuracy of the accurate carbon load model of the direct-injection gasoline engine particle trap is verified. By weighing the GPF carrier, the effect of various modified parameters of the engine on the calculation of the model carbon load can be analyzed. By optimizing the models, the simulation results are closer to the vehicle performance. The research results are beneficial to realize the GPF offline calibration function, improve the GPF control strategy, and reduce the corresponding development cost.
2019, 38(6): 884-891.
doi: 10.13433/j.cnki.1003-8728.20180267
Abstract:
In order to reduce the particulate emissions of GDI engines, a 3D numerical model of a certain type of cylinder direct injection gasoline engine was built and the AVL-Fire was used to simulate the generation process of engine particulates. The particulate generation mechanisms in cylinders and secondary injection strategies for particulates were investigated. The effect of the law is firstly simulated by the single injection strategy under the original fuel injection parameters. Secondly, two injections of fuel were performed based on the single injection to explore the influence of injection timing and the injection ratio on particle generation. According to the influence laws, the following conclusions have been obtained:in the original jet injection strategy, the incomplete evaporation of the oil film on the surface of the oil film caused diffusion combustion and resulted in the generation of large amounts of soot; Under the secondary injection strategy, as the second injection timing postponed, the final soot mass fraction and the number concentration firstly decreased and then increased. The optimized secondary fuel injection strategy has a final soot mass fraction of 1.28×10-11, and the final soot number concentration was 2.99×1013, which were 46.89% and 31.42% lower than the single injection strategy respectively. Therefore, a reasonable development of secondary injection strategy can reduce the production of soot.
In order to reduce the particulate emissions of GDI engines, a 3D numerical model of a certain type of cylinder direct injection gasoline engine was built and the AVL-Fire was used to simulate the generation process of engine particulates. The particulate generation mechanisms in cylinders and secondary injection strategies for particulates were investigated. The effect of the law is firstly simulated by the single injection strategy under the original fuel injection parameters. Secondly, two injections of fuel were performed based on the single injection to explore the influence of injection timing and the injection ratio on particle generation. According to the influence laws, the following conclusions have been obtained:in the original jet injection strategy, the incomplete evaporation of the oil film on the surface of the oil film caused diffusion combustion and resulted in the generation of large amounts of soot; Under the secondary injection strategy, as the second injection timing postponed, the final soot mass fraction and the number concentration firstly decreased and then increased. The optimized secondary fuel injection strategy has a final soot mass fraction of 1.28×10-11, and the final soot number concentration was 2.99×1013, which were 46.89% and 31.42% lower than the single injection strategy respectively. Therefore, a reasonable development of secondary injection strategy can reduce the production of soot.
2019, 38(6): 892-896.
doi: 10.13433/j.cnki.1003-8728.20190049
Abstract:
A control scheme is put forward for vertical CNC (Computer numerical control) plane grinding machine based on passive compliant control, aiming at some technology characteristics and technological requirements of plane grinding. An impedance models for grinding is established by analyzing the principle of passive compliance control. According to the impedance model, a group of process parameters are derived that can make the grinding process in a dynamic balance. The results showed that the control of pressure is very stable, the positioning accuracy is good, and the surface roughness of workpiece is better. The results can satisfy the general grinding requests. Comparing with the common control methods of vertical grinding machine, the scheme can be used in position servo state and get rid of the special grinding pressure control equipment. It has a good prospect of popularization and application for simplifying the hardware equipment and operation process, improving the processing efficiency and reducing the production cost.
A control scheme is put forward for vertical CNC (Computer numerical control) plane grinding machine based on passive compliant control, aiming at some technology characteristics and technological requirements of plane grinding. An impedance models for grinding is established by analyzing the principle of passive compliance control. According to the impedance model, a group of process parameters are derived that can make the grinding process in a dynamic balance. The results showed that the control of pressure is very stable, the positioning accuracy is good, and the surface roughness of workpiece is better. The results can satisfy the general grinding requests. Comparing with the common control methods of vertical grinding machine, the scheme can be used in position servo state and get rid of the special grinding pressure control equipment. It has a good prospect of popularization and application for simplifying the hardware equipment and operation process, improving the processing efficiency and reducing the production cost.
2019, 38(6): 897-901.
doi: 10.13433/j.cnki.1003-8728.20180261
Abstract:
In view of the poor settlement stability of the fluid magnetic abrasive, the surface modification of solid particles in the abrasive was carried out with the carboxylated multi-wall carbon nanotubes, polydimethyldiallyl ammonium chloride aqueous solution and water-soluble polymer. The structure, morphology and potential of the modified solid particles were characterized. At the same time, FMA with carbonyl iron powder and silicon carbide as suspension phase and deionized water as dispersed phase was prepared. Carbon nanotubes were adsorbed on the surface of the modified carbonyl iron powder particles, which reduced the density of the particles from 4.3 g/cm3 to 1.55 g/cm3 and the modified carbonyl iron powder was not easy to rust. The absolute value of the silicon carbide particle potential was improved to 15.3 mV and 68.7mV respectively and the stability of the abrasives had been greatly improved. Static 20 h to 40 h is stable, and the settlement rate is less than 1%. The viscosity of the FMA could be increased by the addition of the modifier, but the effect on the rheological properties of the FMA was less influence. After the surface modification of solid particles, the settlement stability of fluid magnetic abrasive has been improved.
In view of the poor settlement stability of the fluid magnetic abrasive, the surface modification of solid particles in the abrasive was carried out with the carboxylated multi-wall carbon nanotubes, polydimethyldiallyl ammonium chloride aqueous solution and water-soluble polymer. The structure, morphology and potential of the modified solid particles were characterized. At the same time, FMA with carbonyl iron powder and silicon carbide as suspension phase and deionized water as dispersed phase was prepared. Carbon nanotubes were adsorbed on the surface of the modified carbonyl iron powder particles, which reduced the density of the particles from 4.3 g/cm3 to 1.55 g/cm3 and the modified carbonyl iron powder was not easy to rust. The absolute value of the silicon carbide particle potential was improved to 15.3 mV and 68.7mV respectively and the stability of the abrasives had been greatly improved. Static 20 h to 40 h is stable, and the settlement rate is less than 1%. The viscosity of the FMA could be increased by the addition of the modifier, but the effect on the rheological properties of the FMA was less influence. After the surface modification of solid particles, the settlement stability of fluid magnetic abrasive has been improved.
2019, 38(6): 902-908.
doi: 10.13433/j.cnki.1003-8728.20180264
Abstract:
In the single-point incremental forming process, the back side of the sheet metal is not supported by any support, and the sheet metal is unconstrained between the tool head and the sheet metal, which is easy to cause the sheet forming precision to decrease. A new technique for isostatic pressing support in single point incremental forming is proposed, which provides the effective support for the sheet metal in the forming process. The influence law of the isostatic pressure parameters on the forming force of 1060 aluminum plate was analyzed. The results show that the single-point incremental forming of static pressure support has a certain increase in the force of Fx and Fy in the horizontal direction being compared with the traditional single-point incremental forming, but the increase is not large, and the axial force Fz changes greatly. As the static pressure increases, the axial force increases. The static pressure system was designed and developed, and the variation of the experimental forming force under static pressure was obtained, and the correctness of the simulation was verified.
In the single-point incremental forming process, the back side of the sheet metal is not supported by any support, and the sheet metal is unconstrained between the tool head and the sheet metal, which is easy to cause the sheet forming precision to decrease. A new technique for isostatic pressing support in single point incremental forming is proposed, which provides the effective support for the sheet metal in the forming process. The influence law of the isostatic pressure parameters on the forming force of 1060 aluminum plate was analyzed. The results show that the single-point incremental forming of static pressure support has a certain increase in the force of Fx and Fy in the horizontal direction being compared with the traditional single-point incremental forming, but the increase is not large, and the axial force Fz changes greatly. As the static pressure increases, the axial force increases. The static pressure system was designed and developed, and the variation of the experimental forming force under static pressure was obtained, and the correctness of the simulation was verified.
2019, 38(6): 909-914.
doi: 10.13433/j.cnki.1003-8728.20180245
Abstract:
Aiming at the problem of constant force demand in the process of polishing, the active and compliant control system of constant force polishing of industrial robots is studied. Through the six-dimensional force sensor, the collected force signal is filtered and compensated by gravity, and the actual contact force between the polishing tool and the work pieces is obtained. The fuzzy PID control strategy is adopted to control the constant force compensation device to achieve the smooth position compensation, to ensure the constant contact force between the polishing tool and the workpiece, so as to complete the requirements of the robot on the workpiece smooth constant force polishing. The scheme can meet the requirements of position and force control of polishing robot respectively.
Aiming at the problem of constant force demand in the process of polishing, the active and compliant control system of constant force polishing of industrial robots is studied. Through the six-dimensional force sensor, the collected force signal is filtered and compensated by gravity, and the actual contact force between the polishing tool and the work pieces is obtained. The fuzzy PID control strategy is adopted to control the constant force compensation device to achieve the smooth position compensation, to ensure the constant contact force between the polishing tool and the workpiece, so as to complete the requirements of the robot on the workpiece smooth constant force polishing. The scheme can meet the requirements of position and force control of polishing robot respectively.
2019, 38(6): 915-921.
doi: 10.13433/j.cnki.1003-8728.20180263
Abstract:
This paper studies the multi-objective optimization and design of the structure of a six-component wheel force transducer with the uniform sensitivity and the low coupling considered. Firstly, the position of the strain gauge is determined with the finite element method, and then the force bridge is designed. The optimal Latin hypercube experimental design method is used to analyze the influence of structural parameters on sensitivity and coupling. A multi-objective structural optimization design model is established and solved by NSGA-Ⅱ. After optimization, the maximum coupling of the transducer is reduced to 3.8%, and the condition number is reduced to 2.39. A good balance between two contradictory properties of uniform sensitivity and low coupling has been achieved.
This paper studies the multi-objective optimization and design of the structure of a six-component wheel force transducer with the uniform sensitivity and the low coupling considered. Firstly, the position of the strain gauge is determined with the finite element method, and then the force bridge is designed. The optimal Latin hypercube experimental design method is used to analyze the influence of structural parameters on sensitivity and coupling. A multi-objective structural optimization design model is established and solved by NSGA-Ⅱ. After optimization, the maximum coupling of the transducer is reduced to 3.8%, and the condition number is reduced to 2.39. A good balance between two contradictory properties of uniform sensitivity and low coupling has been achieved.
2019, 38(6): 922-929.
doi: 10.13433/j.cnki.1003-8728.20180260
Abstract:
A vision measurement system is firstly designed by selecting its key components and calculating their performance parameters for the online detection requirements of welding quality for a high-speed serial welding system of silicon chip. Secondly, the intrinsic parameters of the vision measurement system are calibrated, which is then used for distortion correction and pixel-equivalent calculation. Thirdly, the vision detection process is designed for the silicon chip after welding, in which the techniques of image preprocessing, image-masking ROI extraction and improved double-threshold Otsu image segmentation are investigated, and a measurement model for welding-strip offset parameter is established. On this basis, an online vision measurement approach is developed for the welding-equality parameters of solar silicon chips. Finally, the present measurement approach is applied to a high-speed serial welding system of silicon chip. The comprehensive detection rate and measurement time per frame meet the accuracy and real-time requirements in the process of online measurement for welding equality, which lays a good technical foundation for improving welding equality and production efficiency of solar battery modules.
A vision measurement system is firstly designed by selecting its key components and calculating their performance parameters for the online detection requirements of welding quality for a high-speed serial welding system of silicon chip. Secondly, the intrinsic parameters of the vision measurement system are calibrated, which is then used for distortion correction and pixel-equivalent calculation. Thirdly, the vision detection process is designed for the silicon chip after welding, in which the techniques of image preprocessing, image-masking ROI extraction and improved double-threshold Otsu image segmentation are investigated, and a measurement model for welding-strip offset parameter is established. On this basis, an online vision measurement approach is developed for the welding-equality parameters of solar silicon chips. Finally, the present measurement approach is applied to a high-speed serial welding system of silicon chip. The comprehensive detection rate and measurement time per frame meet the accuracy and real-time requirements in the process of online measurement for welding equality, which lays a good technical foundation for improving welding equality and production efficiency of solar battery modules.
2019, 38(6): 930-935.
doi: 10.13433/j.cnki.1003-8728.20180254
Abstract:
To improve the poor real-time performance of the data acquisition system of a traditional vibrating string sensor and increase the number of its channels, a multi-channel data acquisition system was designed based on ARM and AD9833; then it can integrate, collect and adjust the circuit, data storage and power supply of the acquisition system. Centering on the ARM, the system uses the Rife and Quinn algorithm to figure out the frequency according to the relationship between the value to be measured and the output signal frequency to be calculated. The acquisition system realizes the real-time online monitoring of performance information and uses the GPRS or cables to complete data transmission. The data was displayed on PC visual and deposited in the database. The data analysis results show that the acquisition system, compared with the traditional acquisition systems, has a higher accuracy and improves the practicability of the vibrating string sensor.
To improve the poor real-time performance of the data acquisition system of a traditional vibrating string sensor and increase the number of its channels, a multi-channel data acquisition system was designed based on ARM and AD9833; then it can integrate, collect and adjust the circuit, data storage and power supply of the acquisition system. Centering on the ARM, the system uses the Rife and Quinn algorithm to figure out the frequency according to the relationship between the value to be measured and the output signal frequency to be calculated. The acquisition system realizes the real-time online monitoring of performance information and uses the GPRS or cables to complete data transmission. The data was displayed on PC visual and deposited in the database. The data analysis results show that the acquisition system, compared with the traditional acquisition systems, has a higher accuracy and improves the practicability of the vibrating string sensor.
2019, 38(6): 936-941.
doi: 10.13433/j.cnki.1003-8728.20180269
Abstract:
Radar antenna stabilized platform is the key equipment for synthetic aperture radar (SAR) imaging and target tracking. The machining and assembly errors of stable platform parts will cause azimuth and horizontal rollers to tilt. According to the measured axis inclination angle, the vector transformation mathematical model of gyroscope mounted on the carrier is calculated, which makes the angular velocity feedback more accurate from servo control system to DC brushless motor, and thus improves the stability and reliability of radar antenna stabilized platform. The rotation transformation model of radar antenna stabilized platform is modified according to the axis tilt angle. The radar beam pointing angle is calculated in MATLAB according to the rotation transformation model of radar antenna stabilized platform. Finally, the positioning accuracy of SAR imaging is improved, and the error of radar beam pointing is analyzed.
Radar antenna stabilized platform is the key equipment for synthetic aperture radar (SAR) imaging and target tracking. The machining and assembly errors of stable platform parts will cause azimuth and horizontal rollers to tilt. According to the measured axis inclination angle, the vector transformation mathematical model of gyroscope mounted on the carrier is calculated, which makes the angular velocity feedback more accurate from servo control system to DC brushless motor, and thus improves the stability and reliability of radar antenna stabilized platform. The rotation transformation model of radar antenna stabilized platform is modified according to the axis tilt angle. The radar beam pointing angle is calculated in MATLAB according to the rotation transformation model of radar antenna stabilized platform. Finally, the positioning accuracy of SAR imaging is improved, and the error of radar beam pointing is analyzed.
2019, 38(6): 942-946.
doi: 10.13433/j.cnki.1003-8728.20190062
Abstract:
The CRH-3C high-speed EMU running on the Wuhan-Guangzhou section of the Beijing-Guangzhou high-speed railway has been found fatigue cracks in the frame, elevator of skirt plate and other stress concentration points of equipment cabin. But this phenomenon is seldom found in same type EMUs running on the Beijing-Tianjin intercity high-speed railway. The reason is considered to be caused by a large number of tunnel groups in the Wuhan-Guangzhou section. In order to verify this idea, a group of air pressure and strain sensors were mounted in the skirt plate and bottom plate of an EMU equipment cabin. The EMU train was tested in the Nanchang West-Yichun section of the Shanghai-Kunming high-speed railway to acquire aerodynamic load and dynamic stress data under typical conditions, including tunnel driving and meeting zones, etc. According to this test, the variation of aerodynamic loads and dynamic stresses at key positions under several working conditions were analyzed. The results show that there often occurs sudden change of the air pressure amplitude while entering a tunnel or meeting in a tunnel and result in increased stress level of most positions, especially in the center of skirt plate and the bottom plate near the front. The analysis result gives a reasonable explanation for the fatigue failure phenomenon of CRH-3C EMU equipment cabin in Wuhan-Guangzhou section, as well as provides suggestions for the selection of EMU models based on different railway characteristics, and optimization design of equipment cabin structure.
The CRH-3C high-speed EMU running on the Wuhan-Guangzhou section of the Beijing-Guangzhou high-speed railway has been found fatigue cracks in the frame, elevator of skirt plate and other stress concentration points of equipment cabin. But this phenomenon is seldom found in same type EMUs running on the Beijing-Tianjin intercity high-speed railway. The reason is considered to be caused by a large number of tunnel groups in the Wuhan-Guangzhou section. In order to verify this idea, a group of air pressure and strain sensors were mounted in the skirt plate and bottom plate of an EMU equipment cabin. The EMU train was tested in the Nanchang West-Yichun section of the Shanghai-Kunming high-speed railway to acquire aerodynamic load and dynamic stress data under typical conditions, including tunnel driving and meeting zones, etc. According to this test, the variation of aerodynamic loads and dynamic stresses at key positions under several working conditions were analyzed. The results show that there often occurs sudden change of the air pressure amplitude while entering a tunnel or meeting in a tunnel and result in increased stress level of most positions, especially in the center of skirt plate and the bottom plate near the front. The analysis result gives a reasonable explanation for the fatigue failure phenomenon of CRH-3C EMU equipment cabin in Wuhan-Guangzhou section, as well as provides suggestions for the selection of EMU models based on different railway characteristics, and optimization design of equipment cabin structure.
2019, 38(6): 947-952.
doi: 10.13433/j.cnki.1003-8728.20190078
Abstract:
The fault detection algorithm based on the fast feature pyramids and Soft-Cascade was proposed in order to improve the efficiency of the fault detection for the angled cock. Firstly, the fast feature pyramids model was constructed to extract the image multi-scale aggregate channel features. Secondly, the vectorized multi-scale aggregate channel features was used to train the Soft-Cascade fault classifier. Finally, the trained classifier was used to detect whether the angle cock contains a fault. The experimental results show that the fault detection accuracy of the proposed algorithm is of 97.33%, the offline detection speed is up to 43 fps (only 23 ms per image), and the detection efficiency is higher than that by using other algorithms. The present algorithm has the short training time, fast detection speed and low hardware requirements, which can meet the requirements of fault detection for the angle cock.
The fault detection algorithm based on the fast feature pyramids and Soft-Cascade was proposed in order to improve the efficiency of the fault detection for the angled cock. Firstly, the fast feature pyramids model was constructed to extract the image multi-scale aggregate channel features. Secondly, the vectorized multi-scale aggregate channel features was used to train the Soft-Cascade fault classifier. Finally, the trained classifier was used to detect whether the angle cock contains a fault. The experimental results show that the fault detection accuracy of the proposed algorithm is of 97.33%, the offline detection speed is up to 43 fps (only 23 ms per image), and the detection efficiency is higher than that by using other algorithms. The present algorithm has the short training time, fast detection speed and low hardware requirements, which can meet the requirements of fault detection for the angle cock.
2019, 38(6): 953-958.
doi: 10.13433/j.cnki.1003-8728.20180256
Abstract:
In order to further clarify the temperature rise characteristic of engineering vehicle retreaded tire, the geometry model and the finite element analysis model of retreaded tire were built using Creo and ANSYS Workbench software, the boundary conditions of steady state temperature field was determined, then the steady-state temperature field test system for the rolling working condition of engineering vehicle retreaded tire was constructed, and at last the temperature field distribution characteristics and heat flux distribution characteristics of the tire layer, buffer layer, belt layer, tread body layer, tire side layer and toe mouth rubber layer along the width direction and radial direction of the tire were obtained. The simulation and test results show that:the two sides of the tread body layer shoulder has the highest temperature, with the lowest temperature on the belt layer, buffer layer, and both sides along the width direction of tread body layer. The interior temperature of the refurbished tire increased with the speed of vehicle, among them, the temperature of the buffer layer and the tire layer increased greatly, and the tread body layer is the second, and the temperature of the belt layer is the smallest. The maximum heat flux is near the shoulder position of the tread body layer, and the heat flux of belt layer and on both sides of tire layer width direction is the largest, the maximum heat flux is on both sides of the buffer layer width direction, the maximum heat flux is at the junction of the tire side layer and the tread body layer, the maximum heat flux is at the junction of the toe mouth rubber layer and the tread body layer, and the heat flux in the middle part of the wire ring is the largest.
In order to further clarify the temperature rise characteristic of engineering vehicle retreaded tire, the geometry model and the finite element analysis model of retreaded tire were built using Creo and ANSYS Workbench software, the boundary conditions of steady state temperature field was determined, then the steady-state temperature field test system for the rolling working condition of engineering vehicle retreaded tire was constructed, and at last the temperature field distribution characteristics and heat flux distribution characteristics of the tire layer, buffer layer, belt layer, tread body layer, tire side layer and toe mouth rubber layer along the width direction and radial direction of the tire were obtained. The simulation and test results show that:the two sides of the tread body layer shoulder has the highest temperature, with the lowest temperature on the belt layer, buffer layer, and both sides along the width direction of tread body layer. The interior temperature of the refurbished tire increased with the speed of vehicle, among them, the temperature of the buffer layer and the tire layer increased greatly, and the tread body layer is the second, and the temperature of the belt layer is the smallest. The maximum heat flux is near the shoulder position of the tread body layer, and the heat flux of belt layer and on both sides of tire layer width direction is the largest, the maximum heat flux is on both sides of the buffer layer width direction, the maximum heat flux is at the junction of the tire side layer and the tread body layer, the maximum heat flux is at the junction of the toe mouth rubber layer and the tread body layer, and the heat flux in the middle part of the wire ring is the largest.
2019, 38(6): 959-962.
doi: 10.13433/j.cnki.1003-8728.20180252
Abstract:
Automatic holing technology of airplane skin is widely used. The process of pre-connected hole is an important part in the process of automatic holing. In order to solve the instability of pre-connected hole process and improve the arrangement efficiency of pre-connected hole, the pre-connected hole arrangement is abstracted as a mathematical model. The simulated annealing algorithm is used and improved. The algorithm procedure of pre-connected hole arrangement is given. The convergence problem of algorithm is solved. The module of pre-connected hole fast arrangement is developed by using the CATIA secondary development technology. Two typical airplane skin models are used in order to verify the feasibility of algorithm. Results show that the algorithm is stable and reliable and efficient. It can not only develop the process efficiency of pre-connected hole, but also improve the level of aircraft digital assembly.
Automatic holing technology of airplane skin is widely used. The process of pre-connected hole is an important part in the process of automatic holing. In order to solve the instability of pre-connected hole process and improve the arrangement efficiency of pre-connected hole, the pre-connected hole arrangement is abstracted as a mathematical model. The simulated annealing algorithm is used and improved. The algorithm procedure of pre-connected hole arrangement is given. The convergence problem of algorithm is solved. The module of pre-connected hole fast arrangement is developed by using the CATIA secondary development technology. Two typical airplane skin models are used in order to verify the feasibility of algorithm. Results show that the algorithm is stable and reliable and efficient. It can not only develop the process efficiency of pre-connected hole, but also improve the level of aircraft digital assembly.
2019, 38(6): 963-969.
doi: 10.13433/j.cnki.1003-8728.20180248
Abstract:
A large-flow centrifugal refrigeration compressor has an important impact on an airborne vapor compression refrigeration system and a much higher operating efficiency than a small-flow centrifugal refrigeration compressor. The flow of refrigerant R134a in the pump impeller of the existing two-stage small-flow centrifugal refrigeration compressor was analyzed through experiments and CFD simulations. The results show that under the condition of the experimental parameters, the secondary refrigerant phenomenon occurs in the refrigerant working near the pressure surface of the pump impeller inlet. The gas flow has a cover surface separation and the impeller has a large internal loss. Changing the impeller blade outlet installation can improve the efficiency and pressure ratio. This paper also simulates and calculates different impeller blades to determine the optimal number of blades in the designed model. The comparison of the simulation results of different impeller blades determines the optimal number of blades in the designed model.
A large-flow centrifugal refrigeration compressor has an important impact on an airborne vapor compression refrigeration system and a much higher operating efficiency than a small-flow centrifugal refrigeration compressor. The flow of refrigerant R134a in the pump impeller of the existing two-stage small-flow centrifugal refrigeration compressor was analyzed through experiments and CFD simulations. The results show that under the condition of the experimental parameters, the secondary refrigerant phenomenon occurs in the refrigerant working near the pressure surface of the pump impeller inlet. The gas flow has a cover surface separation and the impeller has a large internal loss. Changing the impeller blade outlet installation can improve the efficiency and pressure ratio. This paper also simulates and calculates different impeller blades to determine the optimal number of blades in the designed model. The comparison of the simulation results of different impeller blades determines the optimal number of blades in the designed model.
2019, 38(6): 970-976.
doi: 10.13433/j.cnki.1003-8728.20180265
Abstract:
Taking a small centrifugal compressor as the object, based on the non-intrusive probability collocation method and numerical analysis, the influence rule of the aerodynamic boundary uncertainty on the aerodynamic performance of the centrifugal compressor is studied, and the influence of the uncertainty of the rotational speed fluctuation on the centrifugal compressor pressure ratio is quantified. An aerodynamic robust design method for centrifugal compressor based on the uncertain analysis method, the surrogate model and the multi-objective optimization algorithm is proposed, which provides an important reference for the design and application of centrifugal compressor and other impeller machinery. The results show that the impeller pressure ratio increases by 4.1% and the pressure ratio variance decreases by 13.52% after optimization. The aerodynamic robustness is enhanced.
Taking a small centrifugal compressor as the object, based on the non-intrusive probability collocation method and numerical analysis, the influence rule of the aerodynamic boundary uncertainty on the aerodynamic performance of the centrifugal compressor is studied, and the influence of the uncertainty of the rotational speed fluctuation on the centrifugal compressor pressure ratio is quantified. An aerodynamic robust design method for centrifugal compressor based on the uncertain analysis method, the surrogate model and the multi-objective optimization algorithm is proposed, which provides an important reference for the design and application of centrifugal compressor and other impeller machinery. The results show that the impeller pressure ratio increases by 4.1% and the pressure ratio variance decreases by 13.52% after optimization. The aerodynamic robustness is enhanced.
2019, 38(6): 977-984.
doi: 10.13433/j.cnki.1003-8728.20190056
Abstract:
A fuzzy C-Means Clustering Based Evolutionary Algorithm (FCEA) is merged with Efficient Global Optimization (EGO), and a Kriging model is proposed to develop a multi-objective optimization algorithm (FCEA-EGO). In the optimization process of FCEA-EGO algorithm, the fuzzy C-means clustering algorithm is used to select similar individuals from the whole population for genetic operation, and the algorithm is guided to be optimized; Based on the EGO algorithm's correction point selection mechanism, the correction points are gradually corrected to improve the accuracy of the Kriging model. The experimental results show that the FCEA-EGO algorithm has better solving ability than the typical high-price multi-objective optimization algorithms MOEA/D-EGO, ParEGO and SMS-EGO. Finally, based on the FCEA-EGO algorithm, the gear reducer of a light aircraft is optimized, and its ability to solve practical engineering optimization problems is verified.
A fuzzy C-Means Clustering Based Evolutionary Algorithm (FCEA) is merged with Efficient Global Optimization (EGO), and a Kriging model is proposed to develop a multi-objective optimization algorithm (FCEA-EGO). In the optimization process of FCEA-EGO algorithm, the fuzzy C-means clustering algorithm is used to select similar individuals from the whole population for genetic operation, and the algorithm is guided to be optimized; Based on the EGO algorithm's correction point selection mechanism, the correction points are gradually corrected to improve the accuracy of the Kriging model. The experimental results show that the FCEA-EGO algorithm has better solving ability than the typical high-price multi-objective optimization algorithms MOEA/D-EGO, ParEGO and SMS-EGO. Finally, based on the FCEA-EGO algorithm, the gear reducer of a light aircraft is optimized, and its ability to solve practical engineering optimization problems is verified.
