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RSS2021 Vol. 40, No. 12
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Parameter Design of Anti-vibration Exoskeleton Damping Mechanism for Operating Hand-held Power Tools
2021, 40(12): 1805-1812.
doi: 10.13433/j.cnki.1003-8728.20200286
PDF 2983KB
Abstract:
In view of the negative impact of hand-held vibration tools on the human body and the lack of existing vibration reduction measures, a lightweight and comfortable portable upper extremity anti-vibration exoskeleton was proposed as new personal protective equipment. The structural parameter of its core component damper is designed to improve the vibration reduction performance. The rectangular coordinate method is used to build and solve the equation for the motion of the mechanism. According to the Lagrange principle, the differential equation of motion of the man-machine coupled system is established, and the key parameters that affect the anti-vibration exoskeleton damping performance are analyzed. Based on the mechanical model of human-machine coupling and the initial prototype parameters of exoskeleton, the standard orthogonal table L27(313) is selected by Minitab to design 5-factor 3-level orthogonal simulation test, which investigates the interaction between factors. The results of ADAMS simulation show that the influence significant order of the factors and the interaction terms on force F is l2/l1>l2/l1×c1>l2/l1×c2>c2>c1>c1×c2>k2>k1. The installation position l2/l1 of the shock absorber is the main factor affecting the shock absorption performance. The optimal level combination of factors within the test range is l2/l1(1)k1(1)c1(3)k2(1)c2(3). Under the optimal level combination, the exoskeleton achieves a better vibration reduction effect.
In view of the negative impact of hand-held vibration tools on the human body and the lack of existing vibration reduction measures, a lightweight and comfortable portable upper extremity anti-vibration exoskeleton was proposed as new personal protective equipment. The structural parameter of its core component damper is designed to improve the vibration reduction performance. The rectangular coordinate method is used to build and solve the equation for the motion of the mechanism. According to the Lagrange principle, the differential equation of motion of the man-machine coupled system is established, and the key parameters that affect the anti-vibration exoskeleton damping performance are analyzed. Based on the mechanical model of human-machine coupling and the initial prototype parameters of exoskeleton, the standard orthogonal table L27(313) is selected by Minitab to design 5-factor 3-level orthogonal simulation test, which investigates the interaction between factors. The results of ADAMS simulation show that the influence significant order of the factors and the interaction terms on force F is l2/l1>l2/l1×c1>l2/l1×c2>c2>c1>c1×c2>k2>k1. The installation position l2/l1 of the shock absorber is the main factor affecting the shock absorption performance. The optimal level combination of factors within the test range is l2/l1(1)k1(1)c1(3)k2(1)c2(3). Under the optimal level combination, the exoskeleton achieves a better vibration reduction effect.
2021, 40(12): 1813-1819.
doi: 10.13433/j.cnki.1003-8728.20200290
Abstract:
Heavy-duty special vehicles are often driven in harsh environments, and in order to protect the transmission system, the hydraulic torque converter is not blocked. In this paper, a shifting strategy optimization method is proposed to improve the transmission efficiency under hydraulic conditions of a hydraulic torque converter. Firstly, according to the actual vehicle data of the TR50 mine car, the optimal dynamic shift schedule is established. Secondly, after analyzing the working characteristics of the torque converter, a mathematical model to calculate the transmission efficiency of the torque converter in real time and an optimization objective function are then established. Finally, based on the optimal dynamic shifting rules, the overall shifting points of each gear are optimized. Simulation analysis of the shifting rules before and after optimization is carried out on the SIMULINK simulation system model. The results show that the optimized shifting law significantly improves the transmission efficiency of the hydraulic torque converter under the hydraulic condition on the basis of ensuring the dynamic performance.
Heavy-duty special vehicles are often driven in harsh environments, and in order to protect the transmission system, the hydraulic torque converter is not blocked. In this paper, a shifting strategy optimization method is proposed to improve the transmission efficiency under hydraulic conditions of a hydraulic torque converter. Firstly, according to the actual vehicle data of the TR50 mine car, the optimal dynamic shift schedule is established. Secondly, after analyzing the working characteristics of the torque converter, a mathematical model to calculate the transmission efficiency of the torque converter in real time and an optimization objective function are then established. Finally, based on the optimal dynamic shifting rules, the overall shifting points of each gear are optimized. Simulation analysis of the shifting rules before and after optimization is carried out on the SIMULINK simulation system model. The results show that the optimized shifting law significantly improves the transmission efficiency of the hydraulic torque converter under the hydraulic condition on the basis of ensuring the dynamic performance.
2021, 40(12): 1820-1828.
doi: 10.13433/j.cnki.1003-8728.20200288
Abstract:
Axial ultrasonic vibration assisted milling technology is one of the latest developments in the field of milling. At present, there are a few studying on the modeling for the milling force. To solve this problem, an ultrasonic milling force modeling method by considering the axial vibration is proposed. According to the coordinates of the movement trajectory of the tool tip in space, the accurate instantaneous cutting thickness model was established, and the chip forming force and friction force models were obtained at different cutting angles. The functional relationship between the impact force and the area of undeformed cut thickness is established, and the instantaneous model of undeformed cut thickness and the instantaneous model for the cutting depth are considered, and the axial impact force model is obtained. Combining the chip forming force model, the friction force model and the axial impact force model, the axial ultrasonic vibration assisted milling force model is sorted out. The result by comparing the experimental value and the predicted of the model shows that the predicted milling force change is consistent with the experimentally measured milling force change, and the maximum peak force contrast error is between 7.53% and 17.35%. The results of this work will provide a theoretical basis for optimizing the milling process assisted by ultrasonic vibration.
Axial ultrasonic vibration assisted milling technology is one of the latest developments in the field of milling. At present, there are a few studying on the modeling for the milling force. To solve this problem, an ultrasonic milling force modeling method by considering the axial vibration is proposed. According to the coordinates of the movement trajectory of the tool tip in space, the accurate instantaneous cutting thickness model was established, and the chip forming force and friction force models were obtained at different cutting angles. The functional relationship between the impact force and the area of undeformed cut thickness is established, and the instantaneous model of undeformed cut thickness and the instantaneous model for the cutting depth are considered, and the axial impact force model is obtained. Combining the chip forming force model, the friction force model and the axial impact force model, the axial ultrasonic vibration assisted milling force model is sorted out. The result by comparing the experimental value and the predicted of the model shows that the predicted milling force change is consistent with the experimentally measured milling force change, and the maximum peak force contrast error is between 7.53% and 17.35%. The results of this work will provide a theoretical basis for optimizing the milling process assisted by ultrasonic vibration.
2021, 40(12): 1829-1835.
doi: 10.13433/j.cnki.1003-8728.20200300
Abstract:
A series of plate heat exchangers with different sizes of pin-fin rows were designed to study their heat transfer efficiency with the COMSOL software. The hot and cold dual-channel model is applied and hollow pin-fin rows are innovatively added to ripples. Multiphysics (fluid flow and temperature) in the hot and cold dual-channel model is studied by numerical simulation method. The simulation results show that at a slow speed, the pin-fin rows can reduce the area on both sides of the channel, thus transferring the temperature more uniformly. Furthermore, the pressure at the outlet of the channel with the pin-fin rows did not change much. To reduce pressure loss, the pin-fin rows should not be installed at the outlet. The simulation results also show that the pin-fin rows can increase the heat transfer efficiency by 3% compared with the traditional plate.
A series of plate heat exchangers with different sizes of pin-fin rows were designed to study their heat transfer efficiency with the COMSOL software. The hot and cold dual-channel model is applied and hollow pin-fin rows are innovatively added to ripples. Multiphysics (fluid flow and temperature) in the hot and cold dual-channel model is studied by numerical simulation method. The simulation results show that at a slow speed, the pin-fin rows can reduce the area on both sides of the channel, thus transferring the temperature more uniformly. Furthermore, the pressure at the outlet of the channel with the pin-fin rows did not change much. To reduce pressure loss, the pin-fin rows should not be installed at the outlet. The simulation results also show that the pin-fin rows can increase the heat transfer efficiency by 3% compared with the traditional plate.
2021, 40(12): 1836-1841.
doi: 10.13433/j.cnki.1003-8728.20200292
Abstract:
In designing and optimizing the rotor profile of a screw compressor, there are many types of curve segments, different and variable equations, and complex calculation processes. In order to carry out the concise design of the rotor profile and improve the design efficiency, a new method for introducing the NURBS curve into the screw rotor meshing line design is proposed. First, we analyze and summarize the typical curve types and derive a unified expression suitable for each type of curve segment. Then we interpolate the fitting of each segment of the meshing line and derive a high-order continuous curve stitching algorithm which solves the continuous problem of the segmented NURBS curve at the common endpoint. We realize that the meshing line is infinitely differentiable within the node interval. Finally, taking the Fusheng profile as an example, a meshing line expressed by a one-stage NURBS high-order continuous expression is generated, its curvature change is calculated, and the dynamic rotor profile is analyzed. The results show that the smoothness and transmission performance of the rotor profile are significantly improved, verifying the feasibility and efficiency of the method, which greatly simplifies the calculation process.
In designing and optimizing the rotor profile of a screw compressor, there are many types of curve segments, different and variable equations, and complex calculation processes. In order to carry out the concise design of the rotor profile and improve the design efficiency, a new method for introducing the NURBS curve into the screw rotor meshing line design is proposed. First, we analyze and summarize the typical curve types and derive a unified expression suitable for each type of curve segment. Then we interpolate the fitting of each segment of the meshing line and derive a high-order continuous curve stitching algorithm which solves the continuous problem of the segmented NURBS curve at the common endpoint. We realize that the meshing line is infinitely differentiable within the node interval. Finally, taking the Fusheng profile as an example, a meshing line expressed by a one-stage NURBS high-order continuous expression is generated, its curvature change is calculated, and the dynamic rotor profile is analyzed. The results show that the smoothness and transmission performance of the rotor profile are significantly improved, verifying the feasibility and efficiency of the method, which greatly simplifies the calculation process.
2021, 40(12): 1842-1848.
doi: 10.13433/j.cnki.1003-8728.20200609
Abstract:
Aiming at the forming task of two-dimensional configuration, a novel programmable shape formation method for swarm robotics is introduced to enable the formed part to flexibly adjust its shape to meet versatile tasks. Under the condition that the target configuration and the initial configuration are stacked, the stratified strategy is designed to transform the problem of parallel collaboration of large-scale autonomous individuals into the planning and filling of individuals at the edge of the aggregation. Then, the stratified forming method with three stages of pretreatment, chain planning and chain filling is proposed to direct the robots to perform the shape formation task. Finally, the physical prototype with nine lattice mobile robots is performed to verify the present stratified forming strategy and method.
Aiming at the forming task of two-dimensional configuration, a novel programmable shape formation method for swarm robotics is introduced to enable the formed part to flexibly adjust its shape to meet versatile tasks. Under the condition that the target configuration and the initial configuration are stacked, the stratified strategy is designed to transform the problem of parallel collaboration of large-scale autonomous individuals into the planning and filling of individuals at the edge of the aggregation. Then, the stratified forming method with three stages of pretreatment, chain planning and chain filling is proposed to direct the robots to perform the shape formation task. Finally, the physical prototype with nine lattice mobile robots is performed to verify the present stratified forming strategy and method.
2021, 40(12): 1849-1855.
doi: 10.13433/j.cnki.1003-8728.20200258
Abstract:
Higher requirements for the degree of freedom and controllability of the profile in the process of designing and optimizing the profile of the cycloidal disc have been proposed. Therefore, the NURBS curve is proposed to be applied in the profile design process of the reducer cycloid disc in this study. After in-depth study of the cycloid profile using NURBS, by sampling the known cycloid profile, obtaining sample points, inversely finding the control points, weight factors and node vectors to obtain a fitted profile that meets the accuracy requirements, the design of virtual prototype and test prototype are completed with this profile. Simulation and experimental results show that the NURBS curve representation method can ensure the transmission accuracy of the cycloid steel ball reducer, which has laid a foundation for further improving the flexibility and local adjustability of the cycloid plate design. It is verified that the transmission error and noise performance of the reducer prototype is obviously superior to the traditional planetary reducers.
Higher requirements for the degree of freedom and controllability of the profile in the process of designing and optimizing the profile of the cycloidal disc have been proposed. Therefore, the NURBS curve is proposed to be applied in the profile design process of the reducer cycloid disc in this study. After in-depth study of the cycloid profile using NURBS, by sampling the known cycloid profile, obtaining sample points, inversely finding the control points, weight factors and node vectors to obtain a fitted profile that meets the accuracy requirements, the design of virtual prototype and test prototype are completed with this profile. Simulation and experimental results show that the NURBS curve representation method can ensure the transmission accuracy of the cycloid steel ball reducer, which has laid a foundation for further improving the flexibility and local adjustability of the cycloid plate design. It is verified that the transmission error and noise performance of the reducer prototype is obviously superior to the traditional planetary reducers.
2021, 40(12): 1856-1862.
doi: 10.13433/j.cnki.1003-8728.20200283
Abstract:
In the spectrum boundary division of gear vibration siganl based on the empirical wavelet transform (EWT), the gear meshing frequency and its sidebands may be divided into different frequency bands, which leads to the unreasonable frequency band division and unsatisfactory AM-FM components. In view of the above problem, this paper proposes an improved empirical wavelet transform method to divide the spectrum boundary according to the spectrum trend. This method can divide the gear meshing frequency and its corresponding sideband into the same frequency band. Then, we can obtain an ideal AM-FM component and realize the adaptive decomposition according to the local characteristics of gear vibration signal spectrum. At the same time, auto-correlation analysis is performed on the extracted AM-FM component, which further enhances the low-frequency weak fault feature extraction effect of the improved EWT. Through the simulation and experiment, the effectiveness and advantage of this proposed method in the low-frequency weak fault feature extraction of the gear are verified.
In the spectrum boundary division of gear vibration siganl based on the empirical wavelet transform (EWT), the gear meshing frequency and its sidebands may be divided into different frequency bands, which leads to the unreasonable frequency band division and unsatisfactory AM-FM components. In view of the above problem, this paper proposes an improved empirical wavelet transform method to divide the spectrum boundary according to the spectrum trend. This method can divide the gear meshing frequency and its corresponding sideband into the same frequency band. Then, we can obtain an ideal AM-FM component and realize the adaptive decomposition according to the local characteristics of gear vibration signal spectrum. At the same time, auto-correlation analysis is performed on the extracted AM-FM component, which further enhances the low-frequency weak fault feature extraction effect of the improved EWT. Through the simulation and experiment, the effectiveness and advantage of this proposed method in the low-frequency weak fault feature extraction of the gear are verified.
2021, 40(12): 1863-1870.
doi: 10.13433/j.cnki.1003-8728.20200285
Abstract:
The stress calculation method of the flywheel rotor caused by interference assembly is improved. The calculation method of stress caused by filament winding is given. The feedback adaptive genetic algorithm (FAGA) is proposed which gives the population initialization method based on the improved Hamming distances and a feedback mutation method. Based on the FAGA algorithm, considering the stress constraints, mass constraints and different design objectives of the energy per unit mass (EPM) and the energy per unit cost (EPC), the optimization design is carried out. The simulation analysis verifies the rationality of the stress calculation method and the optimization ability of FAGA algorithm. At the same time, it also reveals the influence of the stress constraints, mass constraints and design objectives on the inside and outside diameter ratio, speed, EPM and EPC.
The stress calculation method of the flywheel rotor caused by interference assembly is improved. The calculation method of stress caused by filament winding is given. The feedback adaptive genetic algorithm (FAGA) is proposed which gives the population initialization method based on the improved Hamming distances and a feedback mutation method. Based on the FAGA algorithm, considering the stress constraints, mass constraints and different design objectives of the energy per unit mass (EPM) and the energy per unit cost (EPC), the optimization design is carried out. The simulation analysis verifies the rationality of the stress calculation method and the optimization ability of FAGA algorithm. At the same time, it also reveals the influence of the stress constraints, mass constraints and design objectives on the inside and outside diameter ratio, speed, EPM and EPC.
2021, 40(12): 1871-1876.
doi: 10.13433/j.cnki.1003-8728.20200302
Abstract:
To solve the problem that it is difficult to estimate the number of source signals when the number of observed signals is less than the number of vibration signal sources for mechanical faults, a blind source number estimation method based on variational mode decomposition (VMD) and singular value decomposition (SVD) was proposed in this paper. Firstly, VMD was used to decompose the original vibration signal to obtain several intrinsic mode function (IMF). Then, IMF was recombined to obtain the covariance matrix of multidimensional observation signals. Finally, the number of signal sources was determined according to the result of singular value decomposition. Simulation signal analysis verifies the effectiveness of the method. And the method is also applied to the vibration signals of the bearing composite faults, and the analysis results show that the method can achieve reliable estimation of the number of sources under underdetermined conditions.
To solve the problem that it is difficult to estimate the number of source signals when the number of observed signals is less than the number of vibration signal sources for mechanical faults, a blind source number estimation method based on variational mode decomposition (VMD) and singular value decomposition (SVD) was proposed in this paper. Firstly, VMD was used to decompose the original vibration signal to obtain several intrinsic mode function (IMF). Then, IMF was recombined to obtain the covariance matrix of multidimensional observation signals. Finally, the number of signal sources was determined according to the result of singular value decomposition. Simulation signal analysis verifies the effectiveness of the method. And the method is also applied to the vibration signals of the bearing composite faults, and the analysis results show that the method can achieve reliable estimation of the number of sources under underdetermined conditions.
2021, 40(12): 1877-1884.
doi: 10.13433/j.cnki.1003-8728.20200289
Abstract:
Due to the interference of various factors, the omnidirectional AGV usually deviates from its expected paths. Aiming at this problem, the omnidirectional AGV prototype based on the hub motor was developed and the pose correction research and experiment were carried out on it. Firstly, based on the motion characteristics of the four-wheel independent drive prototype, a kinematics analysis was performed to obtain the relationship between the rotational angle and the rotation speed in different steering modes. Secondly, the pose deviation is decomposed into angular deviation and position deviation. An integrated control strategy combining fuzzy PID control and multi-step prediction optimal control is proposed to eliminate the path deviation. And a decoupling computation was done between hub and steering motors. Finally, the simulation of the combining control strategy was performed. And based on the prototype, the path tracking experiments on arc and straight lines were performed. The results show that the omnidirectional AGV can achieve path tracking and has a good corrective performance.
Due to the interference of various factors, the omnidirectional AGV usually deviates from its expected paths. Aiming at this problem, the omnidirectional AGV prototype based on the hub motor was developed and the pose correction research and experiment were carried out on it. Firstly, based on the motion characteristics of the four-wheel independent drive prototype, a kinematics analysis was performed to obtain the relationship between the rotational angle and the rotation speed in different steering modes. Secondly, the pose deviation is decomposed into angular deviation and position deviation. An integrated control strategy combining fuzzy PID control and multi-step prediction optimal control is proposed to eliminate the path deviation. And a decoupling computation was done between hub and steering motors. Finally, the simulation of the combining control strategy was performed. And based on the prototype, the path tracking experiments on arc and straight lines were performed. The results show that the omnidirectional AGV can achieve path tracking and has a good corrective performance.
2021, 40(12): 1885-1891.
doi: 10.13433/j.cnki.1003-8728.20200298
Abstract:
In order to improve the ability of hexapod robot to adapt to rough terrain, a hexapod bionic robot based on the raspberry PI visual navigation was developed. The mechanical structure of the hexapod bionic robot was designed with the 3D software SolidWorks. By establishing the D-H coordinate system and gait model, the forward and inverse kinematics equation of the robot and the kinematic model for the hexapod bionic robot was constructed. The gait planning of the swing and support phase of hexapod bionic robot was carried out with the polynomial difference fitting. MATLAB-ADAMS was used to jointly complete the pose simulation of the hexapod bionic robot, and the verification of the hexapod bionic robot was carried out. The experimental results show that the gait design can effectively track the leg trajectory of the hexapod bionic robot, which verifies the correctness and effectiveness of the gait design, and provides reference for improving the walking of the multi legged robot.
In order to improve the ability of hexapod robot to adapt to rough terrain, a hexapod bionic robot based on the raspberry PI visual navigation was developed. The mechanical structure of the hexapod bionic robot was designed with the 3D software SolidWorks. By establishing the D-H coordinate system and gait model, the forward and inverse kinematics equation of the robot and the kinematic model for the hexapod bionic robot was constructed. The gait planning of the swing and support phase of hexapod bionic robot was carried out with the polynomial difference fitting. MATLAB-ADAMS was used to jointly complete the pose simulation of the hexapod bionic robot, and the verification of the hexapod bionic robot was carried out. The experimental results show that the gait design can effectively track the leg trajectory of the hexapod bionic robot, which verifies the correctness and effectiveness of the gait design, and provides reference for improving the walking of the multi legged robot.
2021, 40(12): 1892-1897.
doi: 10.13433/j.cnki.1003-8728.20200617
Abstract:
This paper mainly studies the application of hydroforming technology in the forming process of complicated long flange box-shaped parts. At first, the mechanical properties and forming properties of the materials of this kind of parts are tested and analyzed, the forming limit of the material is obtained, and the hydroforming scheme is determined. Then, the finite element simulation model of the box-shaped part is established, and the variation of the material wall thickness during hydroforming is simulated. The key process parameters, low pressure filling time TLP, plastic time TIP, maximum blank holder force Fmax, liduid flow rate Vel%, maximum forming force Pmax and aging time Tw, were redesigned by forming defect analysis. The process parameters were further optimized by the combination of numerical simulation and experimental verification. Finally, the hydroforming process of the box-shaped parts was reconstructed, and the optimal process parameters were determined. This study greatly improves the manufacturing efficiency and product quality, and lays a technological foundation for the hydroforming of the box-shaped parts with low plasticity and difficult deformation.
This paper mainly studies the application of hydroforming technology in the forming process of complicated long flange box-shaped parts. At first, the mechanical properties and forming properties of the materials of this kind of parts are tested and analyzed, the forming limit of the material is obtained, and the hydroforming scheme is determined. Then, the finite element simulation model of the box-shaped part is established, and the variation of the material wall thickness during hydroforming is simulated. The key process parameters, low pressure filling time TLP, plastic time TIP, maximum blank holder force Fmax, liduid flow rate Vel%, maximum forming force Pmax and aging time Tw, were redesigned by forming defect analysis. The process parameters were further optimized by the combination of numerical simulation and experimental verification. Finally, the hydroforming process of the box-shaped parts was reconstructed, and the optimal process parameters were determined. This study greatly improves the manufacturing efficiency and product quality, and lays a technological foundation for the hydroforming of the box-shaped parts with low plasticity and difficult deformation.
Acoustic Emission Characteristic Analysis of Tensile Damage Process for DP780 Weld Bonding Specimens
2021, 40(12): 1898-1903.
doi: 10.13433/j.cnki.1003-8728.20200299
Abstract:
The response surface experiment of weld bonding was carried out for 1.2 mm thick DP780 high-strength steel sheet. The Acoustic Emission(AE) signals of weld bonding joints were collected in the tensile process. The diagram of impact counting in the tensile process were fitted. The signals were decomposed by using the wavelet packet, and the normalized energy characteristics were analyzed. The time-domain and frequency-domain characteristics of AE signals of interfacial fracture and sheet fracture were analyzed. The regression model between the cumulative impact counting and welding parameters was established. The results show that the failure modes of interfacial fracture and sheet fracture produce AE signals at yield and fracture stages. The frequency distributions of the two failure modes are similar. The frequencies distribution of yield stage and fracture moment are 31.25-281.15 kHz and 31.25-125 kHz, respectively. However, the interfacial fracture produces more AE signals than the sheet fracture at the moment of adhesive layer fracture; there is a negative correlation between the cumulative impact counting and the welding current when the adhesive layer fails.
The response surface experiment of weld bonding was carried out for 1.2 mm thick DP780 high-strength steel sheet. The Acoustic Emission(AE) signals of weld bonding joints were collected in the tensile process. The diagram of impact counting in the tensile process were fitted. The signals were decomposed by using the wavelet packet, and the normalized energy characteristics were analyzed. The time-domain and frequency-domain characteristics of AE signals of interfacial fracture and sheet fracture were analyzed. The regression model between the cumulative impact counting and welding parameters was established. The results show that the failure modes of interfacial fracture and sheet fracture produce AE signals at yield and fracture stages. The frequency distributions of the two failure modes are similar. The frequencies distribution of yield stage and fracture moment are 31.25-281.15 kHz and 31.25-125 kHz, respectively. However, the interfacial fracture produces more AE signals than the sheet fracture at the moment of adhesive layer fracture; there is a negative correlation between the cumulative impact counting and the welding current when the adhesive layer fails.
2021, 40(12): 1904-1912.
doi: 10.13433/j.cnki.1003-8728.20200259
Abstract:
To overcome the slow response speed, low tracking accuracy and poor anti-interference ability of an electro-hydraulic position servo system due to parameter uncertainty, nonlinear and complex time-variance, an improved PSO algorithm that has higher tracking accuracy and vibration suppression capability is proposed. Firstly, the error state space equation of the electro-hydraulic position servo system is established. Secondly, an auto disturbance rejection control model is constructed by adopting a third-order tracking differentiator, an expansion state observer and a state error feedback law. Thirdly, the premature and local minimum of inertia weight decreasing PSO algorithm is analyzed. Taking into consideration the influence of the number of particle iterations and the distance between the current particle and the global optimal particle on the optimization result, an improved PSO algorithm is proposed. Finally, the improved PSO algorithm is applied to the auto disturbance rejection controller designed in the paper to improve its control performance. The simulation and experimental results show that the improved PSO algorithm has the advantages of high position tracking accuracy and good anti-interference ability.
To overcome the slow response speed, low tracking accuracy and poor anti-interference ability of an electro-hydraulic position servo system due to parameter uncertainty, nonlinear and complex time-variance, an improved PSO algorithm that has higher tracking accuracy and vibration suppression capability is proposed. Firstly, the error state space equation of the electro-hydraulic position servo system is established. Secondly, an auto disturbance rejection control model is constructed by adopting a third-order tracking differentiator, an expansion state observer and a state error feedback law. Thirdly, the premature and local minimum of inertia weight decreasing PSO algorithm is analyzed. Taking into consideration the influence of the number of particle iterations and the distance between the current particle and the global optimal particle on the optimization result, an improved PSO algorithm is proposed. Finally, the improved PSO algorithm is applied to the auto disturbance rejection controller designed in the paper to improve its control performance. The simulation and experimental results show that the improved PSO algorithm has the advantages of high position tracking accuracy and good anti-interference ability.
2021, 40(12): 1913-1928.
doi: 10.13433/j.cnki.1003-8728.20200588
Abstract:
In recent years, there is an increasing demand for high-quality micro-hole structures in electronics, medicine, aerospace and other industries. However, low machining accuracy, limited machining radius and difficulty in machining complex parts limit its application. The traditional micro-hole processing method can not meet the requirements of high processing quality, and there are still many problems to be solved. The problems of electrochemical, micro Electrochemical machining, ultrasonic, femtosecond laser, composite machining, and other ultra-precision machining methods in micro-hole machining is summarized, and the characteristics of different ultra-precision machining methods and the research progress of corresponding problems is summarized. Finally, the future development trend in the micro-hole machining methods has prospected.
In recent years, there is an increasing demand for high-quality micro-hole structures in electronics, medicine, aerospace and other industries. However, low machining accuracy, limited machining radius and difficulty in machining complex parts limit its application. The traditional micro-hole processing method can not meet the requirements of high processing quality, and there are still many problems to be solved. The problems of electrochemical, micro Electrochemical machining, ultrasonic, femtosecond laser, composite machining, and other ultra-precision machining methods in micro-hole machining is summarized, and the characteristics of different ultra-precision machining methods and the research progress of corresponding problems is summarized. Finally, the future development trend in the micro-hole machining methods has prospected.
2021, 40(12): 1929-1938.
doi: 10.13433/j.cnki.1003-8728.20200287
Abstract:
To solve the problem that lithium battery state of charge (SoC) is difficult to be estimated, put forward the polarization voltage correction model (VCM) and improved beetle antennae search optimized extended Kalman filtering algorithm (IBAS-EKF) can realize battery SoC accurate estimates. Based on the third-order RC battery model and parameter identification, Elman recurrent neural network is used to realize on-line correction and optimization of model polarization voltage to form VCM model. The system noise covariance matrix and measurement noise covariance matrix of the improved beetle antennae search optimized extended Kalman filtering algorithm is used to form the IBAS-EKF lithium battery SoC estimation algorithm. Working urban dynamometer driving schedule test on the test platform, the results show that each error index of IBAS-EKF lithium battery SoC estimation algorithm based on VCM model is lower than the traditional SoC estimation algorithm, and the estimation error is within 0.6 %, which meets the requirements of practical engineering.
To solve the problem that lithium battery state of charge (SoC) is difficult to be estimated, put forward the polarization voltage correction model (VCM) and improved beetle antennae search optimized extended Kalman filtering algorithm (IBAS-EKF) can realize battery SoC accurate estimates. Based on the third-order RC battery model and parameter identification, Elman recurrent neural network is used to realize on-line correction and optimization of model polarization voltage to form VCM model. The system noise covariance matrix and measurement noise covariance matrix of the improved beetle antennae search optimized extended Kalman filtering algorithm is used to form the IBAS-EKF lithium battery SoC estimation algorithm. Working urban dynamometer driving schedule test on the test platform, the results show that each error index of IBAS-EKF lithium battery SoC estimation algorithm based on VCM model is lower than the traditional SoC estimation algorithm, and the estimation error is within 0.6 %, which meets the requirements of practical engineering.
2021, 40(12): 1939-1943.
doi: 10.13433/j.cnki.1003-8728.20200284
Abstract:
In order to improve the efficiency and accuracy of the large foreign body detection of belt conveyor in the underground coal mine, a large foreign body detection system based on machine vision is designed. The overall framework of the detection system for large foreign bodies is constructed, and the hardware design and selection are carried out. The flow chart of the large foreign body detection system is given. Based on the frame difference method, the threshold classification and Select-Shape operator, the algorithm of the large foreign body recognition for belt conveyor is designed, and the large foreign body is tracked by using Kalman filter. Finally, the host computer software of large foreign body detection system is designed, an experimental platform for the foreign body detection is built, and the relevant experiments are carried out. The experimental results show that the recognition accuracy is of 99.5% for the large foreign body exceeding the set threshold. The results are of great significance for preventing the belt tearing, maintaining the stable operation of belt conveyor and realizing the intelligent production in the coal mine enterprises.
In order to improve the efficiency and accuracy of the large foreign body detection of belt conveyor in the underground coal mine, a large foreign body detection system based on machine vision is designed. The overall framework of the detection system for large foreign bodies is constructed, and the hardware design and selection are carried out. The flow chart of the large foreign body detection system is given. Based on the frame difference method, the threshold classification and Select-Shape operator, the algorithm of the large foreign body recognition for belt conveyor is designed, and the large foreign body is tracked by using Kalman filter. Finally, the host computer software of large foreign body detection system is designed, an experimental platform for the foreign body detection is built, and the relevant experiments are carried out. The experimental results show that the recognition accuracy is of 99.5% for the large foreign body exceeding the set threshold. The results are of great significance for preventing the belt tearing, maintaining the stable operation of belt conveyor and realizing the intelligent production in the coal mine enterprises.
2021, 40(12): 1944-1951.
doi: 10.13433/j.cnki.1003-8728.20200619
Abstract:
Vehicle multi-channel road-load-simulation test is a key method for fast validating vehicle structure strength under service condition. How to accurately and effectively simulate multi-channel random load spectra of the complicated vehicle structures is a crucial problem. In this paper, a load correlation analysis based optimized and control method for vehicle multi-channel load spectra simulation was proposed. Based on the proving ground recorded load spectra of test vehicle, a load spectra frequency-domain coherence analysis method was applied to study the correlation between the wheel hub six-component force loads spectra and the critical structure strain spectra under the proving ground specific road condition. The damage dominant loads spectra of wheel hub six-component forces under the proving ground specific road condition were identified. Therefore, the priority loads channels simulation of iteration test was determined, and dimensionality reduction of loads simulation work was realized. Finally, the vehicle multi-channel road-load-simulation test was conducted according to the present method, and well loads simulation effect was acquired. The research can provide reference for effectively implementation of other vehicle and components multi-channel road-load-simulation test.
Vehicle multi-channel road-load-simulation test is a key method for fast validating vehicle structure strength under service condition. How to accurately and effectively simulate multi-channel random load spectra of the complicated vehicle structures is a crucial problem. In this paper, a load correlation analysis based optimized and control method for vehicle multi-channel load spectra simulation was proposed. Based on the proving ground recorded load spectra of test vehicle, a load spectra frequency-domain coherence analysis method was applied to study the correlation between the wheel hub six-component force loads spectra and the critical structure strain spectra under the proving ground specific road condition. The damage dominant loads spectra of wheel hub six-component forces under the proving ground specific road condition were identified. Therefore, the priority loads channels simulation of iteration test was determined, and dimensionality reduction of loads simulation work was realized. Finally, the vehicle multi-channel road-load-simulation test was conducted according to the present method, and well loads simulation effect was acquired. The research can provide reference for effectively implementation of other vehicle and components multi-channel road-load-simulation test.
2021, 40(12): 1952-1960.
doi: 10.13433/j.cnki.1003-8728.20200297
Abstract:
In order to evaluate various failure modes of vehicle more precisely, a novel fuzzy hybrid evaluation method for failure mode and effects analysis (FMEA) is proposed in this paper. In this method, after selecting the appropriate failure modes by FMEA from vehicle maintenance data, and the weights of the three factors and the weights of failure modes are computed by fuzzy analytic hierarchy process (AHP) and fuzzy multi-objective optimization by Ratio analysis plus full multiplicative form (MULTIMOORA) methods, respectively. Using the logic language to represent the evaluation information of experts and convert it into triangular fuzzy number, this paper combines the objective maintenance data and expert experience judgment, which could make the calculation of fault mode weight more precisely, and make the risk ranking result more reasonable. Finally, the risk assessment method based on maintenance cost and the hybrid evaluation method proposed in this paper are used to evaluate the risk of failure mode of a modern passenger car respectively, and the advantages of the proposed method are verified by comparative analysis and sensitivity analysis.
In order to evaluate various failure modes of vehicle more precisely, a novel fuzzy hybrid evaluation method for failure mode and effects analysis (FMEA) is proposed in this paper. In this method, after selecting the appropriate failure modes by FMEA from vehicle maintenance data, and the weights of the three factors and the weights of failure modes are computed by fuzzy analytic hierarchy process (AHP) and fuzzy multi-objective optimization by Ratio analysis plus full multiplicative form (MULTIMOORA) methods, respectively. Using the logic language to represent the evaluation information of experts and convert it into triangular fuzzy number, this paper combines the objective maintenance data and expert experience judgment, which could make the calculation of fault mode weight more precisely, and make the risk ranking result more reasonable. Finally, the risk assessment method based on maintenance cost and the hybrid evaluation method proposed in this paper are used to evaluate the risk of failure mode of a modern passenger car respectively, and the advantages of the proposed method are verified by comparative analysis and sensitivity analysis.
2021, 40(12): 1961-1965.
doi: 10.13433/j.cnki.1003-8728.20200296
Abstract:
As the aerodynamic drag directly affects the maximum running speed of high-speed train, energy consumption and safety, the three-dimensional numerical simulation method was used to study the train aerodynamic drag of 6 full-size trains running in the interval tunnel with ventilation shaft, and the change of air resistance with time in the tunnel, the resistance distribution characteristics of each train carriage, and the proportion of each carriage bogie in the whole vehicle resistance were analyzed in detail. The results indicate that during the time when the train gradually approached the shaft, the drag coefficient was always decreasing, and the minimum value was 1.57; in the time period after the shaft, the resistance coefficient increases greatly, with the maximum value of 4.85, which is 3.08 times of the minimum value; when the train travels at a constant speed, the air resistance of the tail car takes the largest proportion in the whole vehicle, and the head car is slightly smaller, which is 39.6% and 24.7% respectively; when passing directly below the shaft, the head car′s air resistance accounted for as much as half of the entire vehicle, reaching 53.9%; before passing through the shaft, the bogie resistance of the first five carriages fluctuated between 35% and 45%, while the resistance of the last carriage accounted for only 12.7%; when passing through the shaft, the resistance ratio of bogie in 4 carriages is the largest, with a maximum value of 52.7%, and that of the head car is reduced to 17.0%; after passing through the shaft, the bogie area of the middle 4 cars takes up the largest proportion, and the proportion of the head and tail cars is slightly smaller.
As the aerodynamic drag directly affects the maximum running speed of high-speed train, energy consumption and safety, the three-dimensional numerical simulation method was used to study the train aerodynamic drag of 6 full-size trains running in the interval tunnel with ventilation shaft, and the change of air resistance with time in the tunnel, the resistance distribution characteristics of each train carriage, and the proportion of each carriage bogie in the whole vehicle resistance were analyzed in detail. The results indicate that during the time when the train gradually approached the shaft, the drag coefficient was always decreasing, and the minimum value was 1.57; in the time period after the shaft, the resistance coefficient increases greatly, with the maximum value of 4.85, which is 3.08 times of the minimum value; when the train travels at a constant speed, the air resistance of the tail car takes the largest proportion in the whole vehicle, and the head car is slightly smaller, which is 39.6% and 24.7% respectively; when passing directly below the shaft, the head car′s air resistance accounted for as much as half of the entire vehicle, reaching 53.9%; before passing through the shaft, the bogie resistance of the first five carriages fluctuated between 35% and 45%, while the resistance of the last carriage accounted for only 12.7%; when passing through the shaft, the resistance ratio of bogie in 4 carriages is the largest, with a maximum value of 52.7%, and that of the head car is reduced to 17.0%; after passing through the shaft, the bogie area of the middle 4 cars takes up the largest proportion, and the proportion of the head and tail cars is slightly smaller.
2021, 40(12): 1966-1972.
doi: 10.13433/j.cnki.1003-8728.20200254
Abstract:
To improve the terrain trafficability and walking efficiency of a six-wheel-legged robot in unstructured terrain environment, based on the existing parallel six-wheel-legged robot model, the kinematic model of the six-wheel-legged robot was established. The robot′s movement capability in typical unstructured terrain environments such as convexity, pit, slope and ruggedness is analyzed. The relationship between the robot′s movement capability in typical unstructured terrain environments and its configuration parameters was obtained. Furthermore, the gaits of the six-wheel-legged robot under the typical large-scale unstructured terrain environments are planned. The correctness of the motion model and the feasibility of the gait planning were simulated and verified with the ADAMS software. The results provide reference for the control strategies of the six-wheel-legged robot in unstructured terrain environments.
To improve the terrain trafficability and walking efficiency of a six-wheel-legged robot in unstructured terrain environment, based on the existing parallel six-wheel-legged robot model, the kinematic model of the six-wheel-legged robot was established. The robot′s movement capability in typical unstructured terrain environments such as convexity, pit, slope and ruggedness is analyzed. The relationship between the robot′s movement capability in typical unstructured terrain environments and its configuration parameters was obtained. Furthermore, the gaits of the six-wheel-legged robot under the typical large-scale unstructured terrain environments are planned. The correctness of the motion model and the feasibility of the gait planning were simulated and verified with the ADAMS software. The results provide reference for the control strategies of the six-wheel-legged robot in unstructured terrain environments.
