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RSS2015 Vol. 34, No. 2
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2015, 34(2): 165-168.
doi: 10.13433/j.cnki.1003-8728.2015.0201
PDF 2039KB
Abstract:
Combining with the dynamic equation of the self-designed haptic device, the effect of the unbalanced force on the the performance of the haptic device is analyzed. Under not influencing the force accuracy, the range of variation of gravity imbalance items and center-of-mass coordinates are presented. Combining with Adams and Matlab, the transparency of the device under both gravity balance and imbalance state is analyzed. As the centroid of haptic device is within this range, the inertial force of device will be reduced and the performance will be also enhanced, but not affecting the stiffness and operability.
Combining with the dynamic equation of the self-designed haptic device, the effect of the unbalanced force on the the performance of the haptic device is analyzed. Under not influencing the force accuracy, the range of variation of gravity imbalance items and center-of-mass coordinates are presented. Combining with Adams and Matlab, the transparency of the device under both gravity balance and imbalance state is analyzed. As the centroid of haptic device is within this range, the inertial force of device will be reduced and the performance will be also enhanced, but not affecting the stiffness and operability.
2015, 34(2): 169-172.
doi: 10.13433/j.cnki.1003-8728.2015.0202
Abstract:
A novel four-phase flat-type transverse flux permanent-magnet motor (TFPM) is presented in this paper. In order to solve the bigger cogging torque problem that the TFPM ubiquitously has, the finite element method is adopted to analyze the 3-D magnetic field and the cogging torque of the motor model. The one-phase's cogging torque changing curve with the rotor rotation angle is given. Then the motor stator stagger angle which corresponding to the smallest total cogging torque is calculated by Fourier transform, and the total cogging torque curve is given in this situation. A prototype was designed, and the maximum cogging torques of the single-phase and the prototype were measured. The experimental results verify that the total cogging torque of the motor prototype can be reduced clearly when the stator stagger angle is 45°.
A novel four-phase flat-type transverse flux permanent-magnet motor (TFPM) is presented in this paper. In order to solve the bigger cogging torque problem that the TFPM ubiquitously has, the finite element method is adopted to analyze the 3-D magnetic field and the cogging torque of the motor model. The one-phase's cogging torque changing curve with the rotor rotation angle is given. Then the motor stator stagger angle which corresponding to the smallest total cogging torque is calculated by Fourier transform, and the total cogging torque curve is given in this situation. A prototype was designed, and the maximum cogging torques of the single-phase and the prototype were measured. The experimental results verify that the total cogging torque of the motor prototype can be reduced clearly when the stator stagger angle is 45°.
2015, 34(2): 173-178.
doi: 10.13433/j.cnki.1003-8728.2015.0203
Abstract:
Vibration properties of diesel generator set with a rubber isolator were investigated, which has a power of 6 KW and rated speed of 2 400 r/min. Inherent characteristics and dynamic response of the units have been acquired by finite element method (FEM). The influence of different parameters of isolator on vibration properties of diesel generator set was analyzed. The results show that when the Young's modulus and damping coefficient of the rubber isolator increase to a certain value, vibration amplitudes of the units are inhibited well. Except this, vibration gap at both ends of isolator is narrowed in part, and the other trends to increase.
Vibration properties of diesel generator set with a rubber isolator were investigated, which has a power of 6 KW and rated speed of 2 400 r/min. Inherent characteristics and dynamic response of the units have been acquired by finite element method (FEM). The influence of different parameters of isolator on vibration properties of diesel generator set was analyzed. The results show that when the Young's modulus and damping coefficient of the rubber isolator increase to a certain value, vibration amplitudes of the units are inhibited well. Except this, vibration gap at both ends of isolator is narrowed in part, and the other trends to increase.
2015, 34(2): 179-183.
doi: 10.13433/j.cnki.1003-8728.2015.0204
Abstract:
Supporting stiffness has a great influence on the critical speed and on other dynamic characteristics of rotor. This paper presented a new type of supporting mechanism that not only can effectively separate the horizontal bearing stiffness and vertical stiffness but also is valuable for the study of rotor dynamics. Meanwhile, the stiffness of the supporting mechanism can be adjusted so that the critical speed of rotor system can be controlled. Theoretical analysis is conducted for the performance of adjusting critical speed with this new type of supporting mechanism with the transfer matrix method and the generalized influence coefficient method. The results are verified by finite element method and it is shown that this new type of supporting mechanism can be used effectively to adjust the critical speed of rotor system.
Supporting stiffness has a great influence on the critical speed and on other dynamic characteristics of rotor. This paper presented a new type of supporting mechanism that not only can effectively separate the horizontal bearing stiffness and vertical stiffness but also is valuable for the study of rotor dynamics. Meanwhile, the stiffness of the supporting mechanism can be adjusted so that the critical speed of rotor system can be controlled. Theoretical analysis is conducted for the performance of adjusting critical speed with this new type of supporting mechanism with the transfer matrix method and the generalized influence coefficient method. The results are verified by finite element method and it is shown that this new type of supporting mechanism can be used effectively to adjust the critical speed of rotor system.
2015, 34(2): 184-187.
doi: 10.13433/j.cnki.1003-8728.2015.0205
Abstract:
A pneumatic soft continuum robot joint with 3 degrees-of-freedom is proposed based on the combination drive of the pneumatic artificial muscle and the cable. The joint has such features as compact structure, high flexibility and simple controlet, etc. The forward and inverse kinematics models of this continuum robot joint are built with modified D-H method, by analyzing its structural characteristics. The position kinematics solutions and the velocity kinematics solutions of the joint are solved. The structural rationality and the kinematic equation correctness of the joint are verified though kinematics simulation.
A pneumatic soft continuum robot joint with 3 degrees-of-freedom is proposed based on the combination drive of the pneumatic artificial muscle and the cable. The joint has such features as compact structure, high flexibility and simple controlet, etc. The forward and inverse kinematics models of this continuum robot joint are built with modified D-H method, by analyzing its structural characteristics. The position kinematics solutions and the velocity kinematics solutions of the joint are solved. The structural rationality and the kinematic equation correctness of the joint are verified though kinematics simulation.
2015, 34(2): 188-193.
doi: 10.13433/j.cnki.1003-8728.2015.0206
Abstract:
A novel parallel mechanism of a 4-DOF 3-UPS/UPR that can perform one-dimensional translation and three-dimensional rotations is presented. The degree of freedom of the mechanism is calculated. The kinematics of the mechanism is researched making use of the mapping relation between the input speed of the drive spindle and the output speed of the platform. The forward and reverse solutions of position analysis are presented. The Jacobian and Hessian matrix of the mechanism is derived, and its velocity, acceleration performance and workspace are analyzed. The spatial parallel mechanism can be applied in robot neck, the kinematics performance of the parallel mechanism when the robot's head complete the movement are presented.
A novel parallel mechanism of a 4-DOF 3-UPS/UPR that can perform one-dimensional translation and three-dimensional rotations is presented. The degree of freedom of the mechanism is calculated. The kinematics of the mechanism is researched making use of the mapping relation between the input speed of the drive spindle and the output speed of the platform. The forward and reverse solutions of position analysis are presented. The Jacobian and Hessian matrix of the mechanism is derived, and its velocity, acceleration performance and workspace are analyzed. The spatial parallel mechanism can be applied in robot neck, the kinematics performance of the parallel mechanism when the robot's head complete the movement are presented.
2015, 34(2): 194-198.
doi: 10.13433/j.cnki.1003-8728.2015.0207
Abstract:
A giant magnetostrictive fuel injector is designed with the feature that the valve is driven directly. The whole system is treated as a single degree of freedom linear system, and the dynamics equation of the system is established. The injector needle displacement response without bounce between needle and valve is obtained by solving the dynamics equation. The influence of the bounce is analyzed through initial velocity. And the influence of controlled parameters, the rest position and frequency ratio, are analyzed at the same time. The results demonstrate that the stable equilibrium position must be lower slightly than the resting position so as to ensure the valve close reliably without any excitation, 95% rod elongation are used for opening the valve port when frequency ratio is higher than 5.
A giant magnetostrictive fuel injector is designed with the feature that the valve is driven directly. The whole system is treated as a single degree of freedom linear system, and the dynamics equation of the system is established. The injector needle displacement response without bounce between needle and valve is obtained by solving the dynamics equation. The influence of the bounce is analyzed through initial velocity. And the influence of controlled parameters, the rest position and frequency ratio, are analyzed at the same time. The results demonstrate that the stable equilibrium position must be lower slightly than the resting position so as to ensure the valve close reliably without any excitation, 95% rod elongation are used for opening the valve port when frequency ratio is higher than 5.
2015, 34(2): 199-203.
doi: 10.13433/j.cnki.1003-8728.2015.0208
Abstract:
Aiming at solving the problem of safe human-robot interaction and energy efficiency caused by human-robot sharing their work environment, a variable stiffness actuator with an elastic ring for robot joint has been proposed. The elastic ring's stiffness characteristic was figured out through analytical method, in which the maximum theoretical deflection angle is 1.5°. With the collision and the tossing tests, the actuator's capability of absorbing the shock of impact and energy storage was testified. The results indicate that the variable stiffness actuator with an elastic ring is capable of absorbing shock, and the actual deflection angle up to 1.7°, which ensures safe human-robot interaction. Simultaneously, the effect of energy storage is obvious so as to improve energy efficiency.
Aiming at solving the problem of safe human-robot interaction and energy efficiency caused by human-robot sharing their work environment, a variable stiffness actuator with an elastic ring for robot joint has been proposed. The elastic ring's stiffness characteristic was figured out through analytical method, in which the maximum theoretical deflection angle is 1.5°. With the collision and the tossing tests, the actuator's capability of absorbing the shock of impact and energy storage was testified. The results indicate that the variable stiffness actuator with an elastic ring is capable of absorbing shock, and the actual deflection angle up to 1.7°, which ensures safe human-robot interaction. Simultaneously, the effect of energy storage is obvious so as to improve energy efficiency.
2015, 34(2): 204-208.
doi: 10.13433/j.cnki.1003-8728.2015.0209
Abstract:
In order to improve the precision of the drive system for giant hydraulic press, the friction compensation schemes based on the modified LuGre model are proposed. The dynamic model of the drive system is established, and the friction characteristics of hydraulic press are described based on the modified LuGre model. The PID controller, two-DOF (degree-of-freedom) PID controller and the fuzzy adaptive controller are designed respectively; thereby the validity of the compensation schemes is validated via control system analysis. The simulation results show that the fuzzy control compensation scheme occupies the first place, the two-DOF strategy comes second and the conventional PID methodology is the worst. Adopting the fuzzy adaptive controller based on the compensation strategy, the mean square tracking error (MSE) is decreased to 5.903×10-4, comparing with that of traditional PID control method, 5.771×10-3. Hence, the presented compensation scheme can restraint the negative influence of friction and promote the dynamic performance of the drive system evidently.
In order to improve the precision of the drive system for giant hydraulic press, the friction compensation schemes based on the modified LuGre model are proposed. The dynamic model of the drive system is established, and the friction characteristics of hydraulic press are described based on the modified LuGre model. The PID controller, two-DOF (degree-of-freedom) PID controller and the fuzzy adaptive controller are designed respectively; thereby the validity of the compensation schemes is validated via control system analysis. The simulation results show that the fuzzy control compensation scheme occupies the first place, the two-DOF strategy comes second and the conventional PID methodology is the worst. Adopting the fuzzy adaptive controller based on the compensation strategy, the mean square tracking error (MSE) is decreased to 5.903×10-4, comparing with that of traditional PID control method, 5.771×10-3. Hence, the presented compensation scheme can restraint the negative influence of friction and promote the dynamic performance of the drive system evidently.
2015, 34(2): 209-211.
doi: 10.13433/j.cnki.1003-8728.2015.0210
Abstract:
The new fitting method for calculating the contact deformation between the circular crowned roller and the raceway based on the numerical results is proposed in order to solve the problem that there is no suitable deformation formula for this kind of contact pair. Firstly, the affecting coefficient method for structure analysis is used to analyze the contact deformation between the circular crowned roller and the raceway, and then the multiple linear regression method is applied to obtain the fitting formula of contact deformation. The formula includes the dimensions and crowned parameters of circular crowned roller bearing together with the load parameter, and can be used for fast calculatiing the contact deformation between the circular crowned roller and the raceway. Therefore the formula is suitable to efficiently analyze the dynamics characteristics of the circular crowned roller bearings.
The new fitting method for calculating the contact deformation between the circular crowned roller and the raceway based on the numerical results is proposed in order to solve the problem that there is no suitable deformation formula for this kind of contact pair. Firstly, the affecting coefficient method for structure analysis is used to analyze the contact deformation between the circular crowned roller and the raceway, and then the multiple linear regression method is applied to obtain the fitting formula of contact deformation. The formula includes the dimensions and crowned parameters of circular crowned roller bearing together with the load parameter, and can be used for fast calculatiing the contact deformation between the circular crowned roller and the raceway. Therefore the formula is suitable to efficiently analyze the dynamics characteristics of the circular crowned roller bearings.
2015, 34(2): 212-215.
doi: 10.13433/j.cnki.1003-8728.2015.0211
Abstract:
Due to the influence of Poisson Effect existing in the vibrations of ultrasonic horn along the vertical axis, the horizontal vibrations in the radial directions of horn is caused. Usually in the process of traditional acoustic horn design, the horizontal vibrations are ignored, which results the value of the calculated frequency in theory higher than the actual resonant frequency. In order to make the designed theoretical frequency consistent with actual resonant frequency, the paper studied the cylindrical rod and the simple stepped ultrasonic horn respectably. In the common radius ratios range, the formulas about frequency correction were obtained. Applying the correction coefficient in the design process, the requirements of system design and usage are satisfied, and the energy loss in the energy conservation process is efficiently reduced.
Due to the influence of Poisson Effect existing in the vibrations of ultrasonic horn along the vertical axis, the horizontal vibrations in the radial directions of horn is caused. Usually in the process of traditional acoustic horn design, the horizontal vibrations are ignored, which results the value of the calculated frequency in theory higher than the actual resonant frequency. In order to make the designed theoretical frequency consistent with actual resonant frequency, the paper studied the cylindrical rod and the simple stepped ultrasonic horn respectably. In the common radius ratios range, the formulas about frequency correction were obtained. Applying the correction coefficient in the design process, the requirements of system design and usage are satisfied, and the energy loss in the energy conservation process is efficiently reduced.
2015, 34(2): 216-219.
doi: 10.13433/j.cnki.1003-8728.2015.0212
Abstract:
A 3D visual configuration library was established. The designer can place stage in the freedom space in the visual configuration library according to the required DOF of compliant mechanism. Then DOF space and non-redundant constraints can be chosen intuitively. According to other performance indices, the non-redundant constraints are selected. Finaly, the compliant mechanism with the optimal performance indices is synthesized. In order to verify the validity and convenience of the visual configuration library, a compliant mechanism with two translational DOFs is synthesized. And the finite element method is used to analyze the compliant mechanism. The results show that the output of the compliant mechanism is decoupled and its structure is simple.
A 3D visual configuration library was established. The designer can place stage in the freedom space in the visual configuration library according to the required DOF of compliant mechanism. Then DOF space and non-redundant constraints can be chosen intuitively. According to other performance indices, the non-redundant constraints are selected. Finaly, the compliant mechanism with the optimal performance indices is synthesized. In order to verify the validity and convenience of the visual configuration library, a compliant mechanism with two translational DOFs is synthesized. And the finite element method is used to analyze the compliant mechanism. The results show that the output of the compliant mechanism is decoupled and its structure is simple.
2015, 34(2): 220-223.
doi: 10.13433/j.cnki.1003-8728.2015.0213
Abstract:
The thread-taking-up mechanism of a certain type of high-speed industrial sewing machine was considered as the research object, and the influences of comprehensive errors on the thread-hole trajectory accuracy were analyzed with the consideration of manufacturing errors of linkage lengths and clearance of kinematic pairs. The error transfer function from manufacturing error of linkage length to output trajectory was obtained by using the differential method. And the trajectory of the thread-taking-up mechanism considering the clearance errors of kinematic pairs was calculated based on the continuous contact model. With the comparison between numerical and experimental results, the effects of comprehensive errors on the trajectory accuracy of the thread-taking-up mechanism ware discussed.
The thread-taking-up mechanism of a certain type of high-speed industrial sewing machine was considered as the research object, and the influences of comprehensive errors on the thread-hole trajectory accuracy were analyzed with the consideration of manufacturing errors of linkage lengths and clearance of kinematic pairs. The error transfer function from manufacturing error of linkage length to output trajectory was obtained by using the differential method. And the trajectory of the thread-taking-up mechanism considering the clearance errors of kinematic pairs was calculated based on the continuous contact model. With the comparison between numerical and experimental results, the effects of comprehensive errors on the trajectory accuracy of the thread-taking-up mechanism ware discussed.
2015, 34(2): 224-228.
doi: 10.13433/j.cnki.1003-8728.2015.0214
Abstract:
Taguchi method is used to optimize the four main influencing factors including the irradiation (factor D), exposure time (factor C), liquid surface waiting time (factor B) and the coefficient of shrinkage compensation (factor A). Adopting orthogonal table of the L27(313), the signal-to-noise ratio of the building dimension error is obtained with different level of these factors. Through analyzing the intuitive and variance in orthogonal table, it is found that the factors A, B, D and A×D significantly affect the dimension accuracy, the interaction between the factors A and B also affect on the dimension accuracy. Based on the experimental results, an optimal combination of the integral SL system was concluded. With the optimal combination, an error of ±10 μm in the horizontal X and Y dimension has been reached by using the integral SL system. The confirmation experimental results show that the dimension accuracy has been significantly improved with the optimal combination.
Taguchi method is used to optimize the four main influencing factors including the irradiation (factor D), exposure time (factor C), liquid surface waiting time (factor B) and the coefficient of shrinkage compensation (factor A). Adopting orthogonal table of the L27(313), the signal-to-noise ratio of the building dimension error is obtained with different level of these factors. Through analyzing the intuitive and variance in orthogonal table, it is found that the factors A, B, D and A×D significantly affect the dimension accuracy, the interaction between the factors A and B also affect on the dimension accuracy. Based on the experimental results, an optimal combination of the integral SL system was concluded. With the optimal combination, an error of ±10 μm in the horizontal X and Y dimension has been reached by using the integral SL system. The confirmation experimental results show that the dimension accuracy has been significantly improved with the optimal combination.
2015, 34(2): 229-233.
doi: 10.13433/j.cnki.1003-8728.2015.0215
Abstract:
The ultrasonic echo signal reflecting the debris lubricant contains a lots of information. In order to extract the ultrasonic echo signal submerged in strong background noise, a new de-noising method of ultrasonic scattering echo signal for oil wear debris based on the Dual-Tree Complex Wavelet Transform (DT-CWT) is proposed. Firstly, for the DT-CWT having the approximate shift-invariant and effective de-noising, the ultrasonic scattering echo signals are decomposed by using the DT-CWT, and then the threshold processing of high frequency coefficients is performed, finally, the signal is reconstructed by using the DT-CWT. The simulated and experimental results show that the SNR of the de-noising signal is higher, the RMSE is smaller, the NCC is higher, and the maximum amplitude difference (MAD) is smaller at a decomposition order of six. The DT-CWT de-noising method by using a hard threshold is more obvious than the traditional wavelet de-noising method.
The ultrasonic echo signal reflecting the debris lubricant contains a lots of information. In order to extract the ultrasonic echo signal submerged in strong background noise, a new de-noising method of ultrasonic scattering echo signal for oil wear debris based on the Dual-Tree Complex Wavelet Transform (DT-CWT) is proposed. Firstly, for the DT-CWT having the approximate shift-invariant and effective de-noising, the ultrasonic scattering echo signals are decomposed by using the DT-CWT, and then the threshold processing of high frequency coefficients is performed, finally, the signal is reconstructed by using the DT-CWT. The simulated and experimental results show that the SNR of the de-noising signal is higher, the RMSE is smaller, the NCC is higher, and the maximum amplitude difference (MAD) is smaller at a decomposition order of six. The DT-CWT de-noising method by using a hard threshold is more obvious than the traditional wavelet de-noising method.
2015, 34(2): 234-237.
doi: 10.13433/j.cnki.1003-8728.2015.0216
Abstract:
A reverse design and error correction method for double-face cam is presented. Due to the fact that the type-acceleration of cam follower is sensitive to the cam profile curve error, the cam profile accuracy is improved through correcting the type-acceleration curve. Before the cam profile solid model is generated, the data cloud obtained from the digital measurement of the cam double-face profiles are simplified, reconstructed and justified. Based on the function of the acceleration error and the displacement error of the cam, the profile curve is improved by correcting the fitting error of the type-acceleration curve, which is the second derivative of the profile curve.
A reverse design and error correction method for double-face cam is presented. Due to the fact that the type-acceleration of cam follower is sensitive to the cam profile curve error, the cam profile accuracy is improved through correcting the type-acceleration curve. Before the cam profile solid model is generated, the data cloud obtained from the digital measurement of the cam double-face profiles are simplified, reconstructed and justified. Based on the function of the acceleration error and the displacement error of the cam, the profile curve is improved by correcting the fitting error of the type-acceleration curve, which is the second derivative of the profile curve.
2015, 34(2): 238-241.
doi: 10.13433/j.cnki.1003-8728.2015.0217
Abstract:
Aiming at the difficult problems of determining center frequency of high-frequency resonance and selecting bandwidth of the band-pass filter in the current resonance demodulation technique, an adaptive resonance demodulation technique was used to overcome the drawbacks. The key point of the method is to select adaptively center frequency and bandwidth of band-pass filter. Firstly, the fault signal is decomposed into several intrinsic mode functions (IMF) by empirical mode decomposition (EMD) technique; then, the information entropy of IMF component is calculated, the smallest component of information entropy to determine high-frequency resonance frequency is selected; finaly, the Hilbert transform is used to demodulate the envelope signals after band-pass filter, which obtain low-frequency signal of fault characteristic information. Compared with the existing resonance demodulation method, the adaptive resonance demodnlation method shows better for rolling bearing fault diagnosis in engineering practice.
Aiming at the difficult problems of determining center frequency of high-frequency resonance and selecting bandwidth of the band-pass filter in the current resonance demodulation technique, an adaptive resonance demodulation technique was used to overcome the drawbacks. The key point of the method is to select adaptively center frequency and bandwidth of band-pass filter. Firstly, the fault signal is decomposed into several intrinsic mode functions (IMF) by empirical mode decomposition (EMD) technique; then, the information entropy of IMF component is calculated, the smallest component of information entropy to determine high-frequency resonance frequency is selected; finaly, the Hilbert transform is used to demodulate the envelope signals after band-pass filter, which obtain low-frequency signal of fault characteristic information. Compared with the existing resonance demodulation method, the adaptive resonance demodnlation method shows better for rolling bearing fault diagnosis in engineering practice.
2015, 34(2): 242-246.
doi: 10.13433/j.cnki.1003-8728.2015.0218
Abstract:
A method for slicing the 3D model directly from point cloud data is presented for three dimension printer(3DP). The first is the direction of slicing which is determined according to the fractal dimension (D) and the sum of slice layers. The contour curves generation for rapid prototyping model via ray cutting according to the density of the data point. The number system was firstly used which is composed by D and N, and the smaller of the better for slice plate. After getting the slice plate the point cloud data set is segmented along the building direction to a number of slice layers. The points are projected to the mid-plane of the layer to form a 2D band of scatted points. A number of points are picked up along the band and a NURBS curve is fitted to construct a boundary curve using ray shooting method which is called Ray-NURBS. And the last G codes are given for print according to the NURBS curve. The fitted NURBS curve represent a boundary contour which is more accurately close to the entity and more precise image matching can be gotten. Firstly, used to determine the direction for slicing and the ray shooting method is adopted to define the control points for NURBS curve. The experimental results demonstrate the calculation errors are within the tolerance, and the print time is deduced largely.
A method for slicing the 3D model directly from point cloud data is presented for three dimension printer(3DP). The first is the direction of slicing which is determined according to the fractal dimension (D) and the sum of slice layers. The contour curves generation for rapid prototyping model via ray cutting according to the density of the data point. The number system was firstly used which is composed by D and N, and the smaller of the better for slice plate. After getting the slice plate the point cloud data set is segmented along the building direction to a number of slice layers. The points are projected to the mid-plane of the layer to form a 2D band of scatted points. A number of points are picked up along the band and a NURBS curve is fitted to construct a boundary curve using ray shooting method which is called Ray-NURBS. And the last G codes are given for print according to the NURBS curve. The fitted NURBS curve represent a boundary contour which is more accurately close to the entity and more precise image matching can be gotten. Firstly, used to determine the direction for slicing and the ray shooting method is adopted to define the control points for NURBS curve. The experimental results demonstrate the calculation errors are within the tolerance, and the print time is deduced largely.
2015, 34(2): 247-251.
doi: 10.13433/j.cnki.1003-8728.2015.0219
Abstract:
In order to optimize the cutting parameters in milling for reducing or avoiding the regenerative chatter, on the basis of regenerative chatter theory researches, taking rough machining Titanium alloy TA15 with a flat-end mill made of cemented carbide as the research object, the dynamic mathematical model of tool was established and the regenerative chatter stability lobes were solved in the frequency domain; programming design for analysis algorithm of regenerative chatter stability lobes was done and the chatter stability lobes diagram about the spindle speed and axial cutting depth is obtained by providing the milling force coefficients identified in dynamic milling experiment and the modal parameters obtained in modal analysis experiment; through the end-milling experiments of Titanium alloy, the accuracy of the regenerative chatter stability lobes analysis algorithm was verified.
In order to optimize the cutting parameters in milling for reducing or avoiding the regenerative chatter, on the basis of regenerative chatter theory researches, taking rough machining Titanium alloy TA15 with a flat-end mill made of cemented carbide as the research object, the dynamic mathematical model of tool was established and the regenerative chatter stability lobes were solved in the frequency domain; programming design for analysis algorithm of regenerative chatter stability lobes was done and the chatter stability lobes diagram about the spindle speed and axial cutting depth is obtained by providing the milling force coefficients identified in dynamic milling experiment and the modal parameters obtained in modal analysis experiment; through the end-milling experiments of Titanium alloy, the accuracy of the regenerative chatter stability lobes analysis algorithm was verified.
2015, 34(2): 252-256.
doi: 10.13433/j.cnki.1003-8728.2015.0220
Abstract:
It is the key to reduce the noise and enhance the weak fault signal for the early fault diagnosis. A fault diagnosis method of roller bearing based on empirical mode decomposition and spectrum kurtosis is proposed in this paper. Firstly, roller bearing fault vibration signals were decomposed into a finite number of intrinsic mode functions(IMF). Secondly, pseudo component on sampling signal was remaved based on the values of cross correlation coefficient and kurtosis. The useful IMFs were selected with the value of cross correlation coefficient to reconstruct signal in order to achieve the purpose of noise reduction and prominent high frequency resonant components. The parameters of the band-pass filter was determined based on the spectrum kurtosis. In the end, the envelopment analysis of the reconstruction signal was finished. The proposed method has been applied to fault diagnosis of actual bearing signals and compared with the former algorithms.
It is the key to reduce the noise and enhance the weak fault signal for the early fault diagnosis. A fault diagnosis method of roller bearing based on empirical mode decomposition and spectrum kurtosis is proposed in this paper. Firstly, roller bearing fault vibration signals were decomposed into a finite number of intrinsic mode functions(IMF). Secondly, pseudo component on sampling signal was remaved based on the values of cross correlation coefficient and kurtosis. The useful IMFs were selected with the value of cross correlation coefficient to reconstruct signal in order to achieve the purpose of noise reduction and prominent high frequency resonant components. The parameters of the band-pass filter was determined based on the spectrum kurtosis. In the end, the envelopment analysis of the reconstruction signal was finished. The proposed method has been applied to fault diagnosis of actual bearing signals and compared with the former algorithms.
2015, 34(2): 257-262.
doi: 10.13433/j.cnki.1003-8728.2015.0221
Abstract:
To meet the requirement of materials with different properties distribution in microelectronics manufacturing and packaging field, a concept design of multi-dispensing units' droplet on demand jetting system is presented in this paper. In the proposed system, the dispensing module consists of a pneumatic diaphragm droplet generating unit with stainless steel nozzle for low viscosity fluid, a piezoelectric piston droplet generating unit with stainless steel nozzle and stack piezoelectric element actuator for molten metal, a mechanical valve droplet generating unit for high viscosity fluid. At the same time, the image acquisition system with digital camera and analog camera for the visual guiding and droplet producing process image collection is established. With the proposed system, experiments are carried out for the materials of aqueous mixture, molten metal solder and epoxy resin. The paper analyzed the influence of different viscosity on the liquid droplet jetting process, obtained solder ball and ball grid array with an average diameter of 70.5 μm and the diameter deviation is less than 2%, and also obtained epoxy resin droplet and droplet array with average diameter of 0.6 mm and the diameter deviation is less than 4%. The experimental results show that the system can be used for a variety of different viscosity materials including high viscosity of epoxy resin, metal solder according to the need of microelectronics manufacturing process.
To meet the requirement of materials with different properties distribution in microelectronics manufacturing and packaging field, a concept design of multi-dispensing units' droplet on demand jetting system is presented in this paper. In the proposed system, the dispensing module consists of a pneumatic diaphragm droplet generating unit with stainless steel nozzle for low viscosity fluid, a piezoelectric piston droplet generating unit with stainless steel nozzle and stack piezoelectric element actuator for molten metal, a mechanical valve droplet generating unit for high viscosity fluid. At the same time, the image acquisition system with digital camera and analog camera for the visual guiding and droplet producing process image collection is established. With the proposed system, experiments are carried out for the materials of aqueous mixture, molten metal solder and epoxy resin. The paper analyzed the influence of different viscosity on the liquid droplet jetting process, obtained solder ball and ball grid array with an average diameter of 70.5 μm and the diameter deviation is less than 2%, and also obtained epoxy resin droplet and droplet array with average diameter of 0.6 mm and the diameter deviation is less than 4%. The experimental results show that the system can be used for a variety of different viscosity materials including high viscosity of epoxy resin, metal solder according to the need of microelectronics manufacturing process.
2015, 34(2): 263-267.
doi: 10.13433/j.cnki.1003-8728.2015.0222
Abstract:
The new measurement method for the close clearance of piston ring is introduced based on the computer vision, which can automatically inspect the close clearance with high precision and efficiency. The correctness of original measured information is ensured by positioning the measured object precisely, selecting appropriate lighting conditions and controlling the consistent object distance. In order to provide the accurate and convenient traceability for the measurement, an innovative calibration method is developed. Then, the image processing technique designed for the close clearance and data operation based on the minimum distance method are also presented. Finally, the experimental results prove the high accuracy and stability for measuring the close clearance of piston ring.
The new measurement method for the close clearance of piston ring is introduced based on the computer vision, which can automatically inspect the close clearance with high precision and efficiency. The correctness of original measured information is ensured by positioning the measured object precisely, selecting appropriate lighting conditions and controlling the consistent object distance. In order to provide the accurate and convenient traceability for the measurement, an innovative calibration method is developed. Then, the image processing technique designed for the close clearance and data operation based on the minimum distance method are also presented. Finally, the experimental results prove the high accuracy and stability for measuring the close clearance of piston ring.
2015, 34(2): 268-271.
doi: 10.13433/j.cnki.1003-8728.2015.0223
Abstract:
Taking the trapped-oil expansion process in small backlash value and rectangle relief groove style as an example, the accurate parametric model for relief area calculation was derived according to the generating principle of the swept area method and the dynamic calculation of mesh point and the intersection point of relief groove line with tooth profile of driving gear and driven gear. The calculation results of relief area was verified by virtual measurement, and the influence of the basic design parameters of gear on relief area was analyzed. The results indicate that the calculation results agree with virtual measurement value, the error of the example case was about 3.86%, the swept area method for relief area calculation was correct; and it is found that the greater the modulus was and the smaller teeth number and modification coefficient was, the greater the relief area was. The swept area method is suitable for the accurate and efficient calculation of relief area in random backlash value.
Taking the trapped-oil expansion process in small backlash value and rectangle relief groove style as an example, the accurate parametric model for relief area calculation was derived according to the generating principle of the swept area method and the dynamic calculation of mesh point and the intersection point of relief groove line with tooth profile of driving gear and driven gear. The calculation results of relief area was verified by virtual measurement, and the influence of the basic design parameters of gear on relief area was analyzed. The results indicate that the calculation results agree with virtual measurement value, the error of the example case was about 3.86%, the swept area method for relief area calculation was correct; and it is found that the greater the modulus was and the smaller teeth number and modification coefficient was, the greater the relief area was. The swept area method is suitable for the accurate and efficient calculation of relief area in random backlash value.
2015, 34(2): 272-276.
doi: 10.13433/j.cnki.1003-8728.2015.0224
Abstract:
The velocity signal of the flow fields in impinging stream mixer (ISM) contains a lot of complicated information. The complexity theory was first introduced to study the chaos phenomenon of the flow field in ISM. Approximate entropy algorithm and sample entropy algorithm were used to study the behavioral complexity of the system. The approximate entropy and sample entropy were calculated under the different parameters. The approximate entropy and sample entropy have both shown good consistency under the different tolerancer, and the sample entropy is better. The study indicates that the ISM has acoustic noise pollution and could increase the behavior complexity of the system by improving the speed, so as to promote the microcosmic mixture efficiency.
The velocity signal of the flow fields in impinging stream mixer (ISM) contains a lot of complicated information. The complexity theory was first introduced to study the chaos phenomenon of the flow field in ISM. Approximate entropy algorithm and sample entropy algorithm were used to study the behavioral complexity of the system. The approximate entropy and sample entropy were calculated under the different parameters. The approximate entropy and sample entropy have both shown good consistency under the different tolerancer, and the sample entropy is better. The study indicates that the ISM has acoustic noise pollution and could increase the behavior complexity of the system by improving the speed, so as to promote the microcosmic mixture efficiency.
2015, 34(2): 277-281.
doi: 10.13433/j.cnki.1003-8728.2015.0225
Abstract:
As a traditional method to solve the problem of modeling and simulation for multi-domain system, Co-simulation has some shortcomings. For example, the interfaces between software may be complex; it may sometimes unstable to cause the fixed step communication; and system must be broken down into different software leads that models may be difficult to use. In this paper, a hierarchical library that contains variable topology models for multi-axis vehicle is developed based on the Modelica, which is a multi-domain united modeling and simulation technology. Also, the method for building this library is introduced. Then, using the components from this library, a whole-vehicle virtual prototype for a 5-axis crane is modeled. Several applications are carried out on this proto-type, including some full-bridge steering cases and a rapid development of 9-axis vehicle system. The result shows that the multi-domain united method is feasible for multi-axis vehicle design and validation, and has its own benefit of simple architecture and highly reusability.
As a traditional method to solve the problem of modeling and simulation for multi-domain system, Co-simulation has some shortcomings. For example, the interfaces between software may be complex; it may sometimes unstable to cause the fixed step communication; and system must be broken down into different software leads that models may be difficult to use. In this paper, a hierarchical library that contains variable topology models for multi-axis vehicle is developed based on the Modelica, which is a multi-domain united modeling and simulation technology. Also, the method for building this library is introduced. Then, using the components from this library, a whole-vehicle virtual prototype for a 5-axis crane is modeled. Several applications are carried out on this proto-type, including some full-bridge steering cases and a rapid development of 9-axis vehicle system. The result shows that the multi-domain united method is feasible for multi-axis vehicle design and validation, and has its own benefit of simple architecture and highly reusability.
2015, 34(2): 282-286.
doi: 10.13433/j.cnki.1003-8728.2015.0226
Abstract:
The optimization design for alignment parameters of double wishbone independent suspension guide mechanism is essential when expecting appropriate change characteristics during the wheel dance. However, whether the simulation result will be reliable depends mainly on the accuracy of mathematical model. In this paper, according to the ADAMS/View optimized results, such a physical prototype will be realized to make tests on a parametric bench, which will verify the reliability of simulation optimization by comparison and provide a more effective and concise platform for double wishbone independent suspension analysis and design.
The optimization design for alignment parameters of double wishbone independent suspension guide mechanism is essential when expecting appropriate change characteristics during the wheel dance. However, whether the simulation result will be reliable depends mainly on the accuracy of mathematical model. In this paper, according to the ADAMS/View optimized results, such a physical prototype will be realized to make tests on a parametric bench, which will verify the reliability of simulation optimization by comparison and provide a more effective and concise platform for double wishbone independent suspension analysis and design.
2015, 34(2): 287-290.
doi: 10.13433/j.cnki.1003-8728.2015.0227
Abstract:
Pit-type non-smooth surface is arranged in vehicle rear end of different models,and its impact on aerodynamic drag is studied. The aerodynamic resistance of different models is obtained through numerical calculation method, and the experiment results verify the reliability. The parameters of three different models such as the tail flow and pressure are simulated, and the parameter differences between smooth model and non-smooth model are compared, and the mechanism of drag reduction for the tail non-smooth surface is analyzed. The results show that the tail non-smooth surface has a certain degree of drag reduction for different models.
Pit-type non-smooth surface is arranged in vehicle rear end of different models,and its impact on aerodynamic drag is studied. The aerodynamic resistance of different models is obtained through numerical calculation method, and the experiment results verify the reliability. The parameters of three different models such as the tail flow and pressure are simulated, and the parameter differences between smooth model and non-smooth model are compared, and the mechanism of drag reduction for the tail non-smooth surface is analyzed. The results show that the tail non-smooth surface has a certain degree of drag reduction for different models.
2015, 34(2): 291-295.
doi: 10.13433/j.cnki.1003-8728.2015.0228
Abstract:
A non-cooperation differential game model of the four-wheel-steering (4WS) vehicle's automatic tracking was constructed based on the vehicle's planar motion differential equation, and the corresponding optimization control objective and algorithm were proposed by using optimal conditions of the differential game theory. Based on this method, the simulations were carried out with high speed ISO Lane Change, Sine Steer and low speed circular motion conditions in Matlab. The simulation results indicated that applying differential game's theory in the 4WS vehicle's automatic tracking research can improve vehicle handling stability and path tracking accuracy effectively.
A non-cooperation differential game model of the four-wheel-steering (4WS) vehicle's automatic tracking was constructed based on the vehicle's planar motion differential equation, and the corresponding optimization control objective and algorithm were proposed by using optimal conditions of the differential game theory. Based on this method, the simulations were carried out with high speed ISO Lane Change, Sine Steer and low speed circular motion conditions in Matlab. The simulation results indicated that applying differential game's theory in the 4WS vehicle's automatic tracking research can improve vehicle handling stability and path tracking accuracy effectively.
2015, 34(2): 296-300.
doi: 10.13433/j.cnki.1003-8728.2015.0229
Abstract:
A finite element model of motorcycle cushion plate was built, and the static analysis and modal analysis were conducted. Considering the multiple conditions of static stiffness and the dynamic frequency characteristics of the plate, the multi-objective problem was converted to a single-objective problem by using linear weighted method, and the multi-objective topography optimization design of the plate subjected to multiple conditions is achieved. The optimized plate has the optimal layout with stiffeners, with a 52.2% reduction in maximum deformation, a 42.2% reduction in maximum stress and a 9.0% increase in the first natural frequency. Both the static and dynamic performances of the plate are significantly improved and the expected effect of optimization is achieved.
A finite element model of motorcycle cushion plate was built, and the static analysis and modal analysis were conducted. Considering the multiple conditions of static stiffness and the dynamic frequency characteristics of the plate, the multi-objective problem was converted to a single-objective problem by using linear weighted method, and the multi-objective topography optimization design of the plate subjected to multiple conditions is achieved. The optimized plate has the optimal layout with stiffeners, with a 52.2% reduction in maximum deformation, a 42.2% reduction in maximum stress and a 9.0% increase in the first natural frequency. Both the static and dynamic performances of the plate are significantly improved and the expected effect of optimization is achieved.
2015, 34(2): 301-306.
doi: 10.13433/j.cnki.1003-8728.2015.0230
Abstract:
For the dynamics of urban road environment and the typical driving behavior of intelligent vehicle, the motion planning method based on the behavior dynamics was proposed. According to the requirements of the intelligent vehicle navigation control, the heading angle and line speed for behavior control variables, the motion planning model based on the behavior dynamics was established. Firstly, based on the intelligent vehicle driving environment and the analysis of the typical driving behavior, the coordinate motion planning model was set up. Secondly, according to the principle of behavior dynamics, respectively by the attractor and repellor expression of target and obstacle, and tend to target and obstacle avoidance the behavior of the control variables attractor and repellor of model was established. Finally, through the weighted synthesis of attraction and repulsion, intelligent vehicle behavior dynamics motion planning model was established, the vehicles in the lateral of the heading angle control and speed control on longitudinal was realized. The simulation experiments show that the present model of the behavior dynamics of motion planning could realize the lane keeping, lane changing and overtaking behavior, and safe driving in the lane.
For the dynamics of urban road environment and the typical driving behavior of intelligent vehicle, the motion planning method based on the behavior dynamics was proposed. According to the requirements of the intelligent vehicle navigation control, the heading angle and line speed for behavior control variables, the motion planning model based on the behavior dynamics was established. Firstly, based on the intelligent vehicle driving environment and the analysis of the typical driving behavior, the coordinate motion planning model was set up. Secondly, according to the principle of behavior dynamics, respectively by the attractor and repellor expression of target and obstacle, and tend to target and obstacle avoidance the behavior of the control variables attractor and repellor of model was established. Finally, through the weighted synthesis of attraction and repulsion, intelligent vehicle behavior dynamics motion planning model was established, the vehicles in the lateral of the heading angle control and speed control on longitudinal was realized. The simulation experiments show that the present model of the behavior dynamics of motion planning could realize the lane keeping, lane changing and overtaking behavior, and safe driving in the lane.
2015, 34(2): 307-310.
doi: 10.13433/j.cnki.1003-8728.2015.0231
Abstract:
The 3 degree-of-freedom dynamics model of Special Double-axle Steering Vehicle was established and the transfer function between evaluation parameters and the front wheel angle was obtained. The virtual experiment of the vehicle was done by ADAMS(Automatic Dynamics Analysis of Mechanical Systems) model, the mathematical model was verified. The step response of the vehicle was analyzed to optimize the steering performance by improving the structure, and the reasonable range of the structure size was obtained.
The 3 degree-of-freedom dynamics model of Special Double-axle Steering Vehicle was established and the transfer function between evaluation parameters and the front wheel angle was obtained. The virtual experiment of the vehicle was done by ADAMS(Automatic Dynamics Analysis of Mechanical Systems) model, the mathematical model was verified. The step response of the vehicle was analyzed to optimize the steering performance by improving the structure, and the reasonable range of the structure size was obtained.
2015, 34(2): 311-314.
doi: 10.13433/j.cnki.1003-8728.2015.0232
Abstract:
An approach to obtain the effect of the initial defects on the thermal expansion coefficients of plain weave C/SiC composite was proposed based on the finite element computational micromechanics (FECM). Firstly, the initial defects were classified by using SEM observations and furthermore the measurements and statistics were carried out according to the SEM images. Then, the entire composite and fiber bundle representative volume element(RVE)models with initial defects were established according to the above-mentioned results. Finally, the thermal expansion coefficients of entire composite RVE models with initial defects were predicted by using the FECM method. The quantitative mapping relationships between all kinds of initial defects and the thermal expansion coefficients of entire composite were obtained based on the above-mentioned method.
An approach to obtain the effect of the initial defects on the thermal expansion coefficients of plain weave C/SiC composite was proposed based on the finite element computational micromechanics (FECM). Firstly, the initial defects were classified by using SEM observations and furthermore the measurements and statistics were carried out according to the SEM images. Then, the entire composite and fiber bundle representative volume element(RVE)models with initial defects were established according to the above-mentioned results. Finally, the thermal expansion coefficients of entire composite RVE models with initial defects were predicted by using the FECM method. The quantitative mapping relationships between all kinds of initial defects and the thermal expansion coefficients of entire composite were obtained based on the above-mentioned method.
2015, 34(2): 315-319.
doi: 10.13433/j.cnki.1003-8728.2015.0233
Abstract:
In order to perfect the failure mechanism of casing under non-uniform loading, the collapsing experiments were performed for C110 casing under non-uniform loading. The non-uniform loading on C110 casing was applied with the sophisticated pressure testing machine and the radial displacements of casings have been obtained under different loading. Simultaneously, the strain of C110 casing was measured in the process of collapsing testing by gluing strain-gauge on the outer surface of C110 casing. Some experimental conclusions such as the yield load casing, instability load of casing, deformation law and failure mechanism have been obtained under non-uniform loading.
In order to perfect the failure mechanism of casing under non-uniform loading, the collapsing experiments were performed for C110 casing under non-uniform loading. The non-uniform loading on C110 casing was applied with the sophisticated pressure testing machine and the radial displacements of casings have been obtained under different loading. Simultaneously, the strain of C110 casing was measured in the process of collapsing testing by gluing strain-gauge on the outer surface of C110 casing. Some experimental conclusions such as the yield load casing, instability load of casing, deformation law and failure mechanism have been obtained under non-uniform loading.
2015, 34(2): 320-324.
doi: 10.13433/j.cnki.1003-8728.2015.0234
Abstract:
In microwave Hall thruster, for depressing vibration gas was ionized to form surface wave plasma near the end plate of the annular Hall effect channel by use of microwave energy which was coupled in through wind coupling generation and stabilization of surface wave plasma is important for thruster performance, this made it necessary to perform plasma experiment first. At different microwave output power, taking argon and krypton separately as propellant, making the end plate of quartz and ceramic separately, through changing the mass flow rate, the gas discharge pattern and property was obtained. According to Langmuir probe diagnosing method, the surface wave plasma was also diagnosed. The experiment results demonstrated that plasma was much easier to generate with a quartz plate compared with the ceramic one. The plasma density was much higher than the critical value, which showed that the experimented plasma was belong to the scope of surface wave plasma.
In microwave Hall thruster, for depressing vibration gas was ionized to form surface wave plasma near the end plate of the annular Hall effect channel by use of microwave energy which was coupled in through wind coupling generation and stabilization of surface wave plasma is important for thruster performance, this made it necessary to perform plasma experiment first. At different microwave output power, taking argon and krypton separately as propellant, making the end plate of quartz and ceramic separately, through changing the mass flow rate, the gas discharge pattern and property was obtained. According to Langmuir probe diagnosing method, the surface wave plasma was also diagnosed. The experiment results demonstrated that plasma was much easier to generate with a quartz plate compared with the ceramic one. The plasma density was much higher than the critical value, which showed that the experimented plasma was belong to the scope of surface wave plasma.
2015, 34(2): 325-328.
doi: 10.13433/j.cnki.1003-8728.2015.0235
Abstract:
The nose landing gear of a certain aircraft had some problems of deformation and clamping stagnation during extension-retraction tests. This study was carried out to analyze these problems. First, the load of the entire mechanism was analyzed combining the experimenting phenomenon. It was concluded that the gaps between key load transmission components lead to these mechanism faults. On the basis of theoretical analysis, the multi-rigid body dynamic analysis using ADAMS and the finite element analysis of the main members bearing load were carried out. The possible range of gap value was analyzed according to errors in manufacturing and assembly. And then, the load analysis of the landing gear mechanism was done in the case that the kinematic pair had gaps and the landing gear was stuck. From the analysis, the following results are concluded. The kinematic pair gaps caused by assembly errors render 8.31 mm long deformation on the primary load-transfer component, the rear bar. The maximum stress is up to 1 220 MPa, which has exceeded the yield limit and causes the mechanism deformation and the change of the load transmission route. It's the reason why the mechanism is stuck.
The nose landing gear of a certain aircraft had some problems of deformation and clamping stagnation during extension-retraction tests. This study was carried out to analyze these problems. First, the load of the entire mechanism was analyzed combining the experimenting phenomenon. It was concluded that the gaps between key load transmission components lead to these mechanism faults. On the basis of theoretical analysis, the multi-rigid body dynamic analysis using ADAMS and the finite element analysis of the main members bearing load were carried out. The possible range of gap value was analyzed according to errors in manufacturing and assembly. And then, the load analysis of the landing gear mechanism was done in the case that the kinematic pair had gaps and the landing gear was stuck. From the analysis, the following results are concluded. The kinematic pair gaps caused by assembly errors render 8.31 mm long deformation on the primary load-transfer component, the rear bar. The maximum stress is up to 1 220 MPa, which has exceeded the yield limit and causes the mechanism deformation and the change of the load transmission route. It's the reason why the mechanism is stuck.
