流体动力与机电控制
关键词：暂无
2024, 46(4):96-103.
DOI: 10.11887/j.cn.202404010
Abstract:
Acoustic mechanical antenna is one of the important types of mechanical antenna, the resonant frequency of acoustic mechanical antenna is highly coupled with its natural frequency. However, the current acoustic mechanical antenna is limited by material size and has high resonant frequency, which can not to meet the needs of very low frequency or lower frequency band. In order to control the resonant frequency of acoustic mechanical antenna, the vibration modeling of acoustic mechanical antenna was carried out. Three methods were proposed:adding unilateral fixed constraint, increasing free end mass and removing some materials of antenna. Proposed method was verified by finite element simulation. Results show that the three methods can effectively control the resonant frequency of acoustic mechanical antenna, and are in good agreement with the analytical model. Influence of three methods of regulating resonant frequency on the electric field or magnetic field intensity radiated by the antenna was studied through the stress distribution, which has important reference significance for the design of acoustic mechanical antenna.
Acoustic mechanical antenna is one of the important types of mechanical antenna, the resonant frequency of acoustic mechanical antenna is highly coupled with its natural frequency. However, the current acoustic mechanical antenna is limited by material size and has high resonant frequency, which can not to meet the needs of very low frequency or lower frequency band. In order to control the resonant frequency of acoustic mechanical antenna, the vibration modeling of acoustic mechanical antenna was carried out. Three methods were proposed:adding unilateral fixed constraint, increasing free end mass and removing some materials of antenna. Proposed method was verified by finite element simulation. Results show that the three methods can effectively control the resonant frequency of acoustic mechanical antenna, and are in good agreement with the analytical model. Influence of three methods of regulating resonant frequency on the electric field or magnetic field intensity radiated by the antenna was studied through the stress distribution, which has important reference significance for the design of acoustic mechanical antenna.
2024, 46(4):104-113.
DOI: 10.11887/j.cn.202404011
Abstract:
The multiple AGV (automated guided vehicle) system is prone to conflict, collision and deadlock in the process of carrying. Therefore, the A* algorithm was improved by introducing multi-valued grid and traffic rules to solve the path planning problem for the multiple AGV system in scenarios where there was passable space beneath shelves. To improve handling efficiency of the multiple AGV system, the planned path was optimized by adding shelf recall mechanism, turning cost and heat cost. A binary heap data structure was also used to improve calculation speed of the path planning. The simulation results show that the improved A* algorithm has the advantages of fast solution and strong deadlock resistance, and can quickly complete the path planning of multi-AGV system in this scenario.
The multiple AGV (automated guided vehicle) system is prone to conflict, collision and deadlock in the process of carrying. Therefore, the A* algorithm was improved by introducing multi-valued grid and traffic rules to solve the path planning problem for the multiple AGV system in scenarios where there was passable space beneath shelves. To improve handling efficiency of the multiple AGV system, the planned path was optimized by adding shelf recall mechanism, turning cost and heat cost. A binary heap data structure was also used to improve calculation speed of the path planning. The simulation results show that the improved A* algorithm has the advantages of fast solution and strong deadlock resistance, and can quickly complete the path planning of multi-AGV system in this scenario.
2024, 46(4):114-124.
DOI: 10.11887/j.cn.202404012
Abstract:
In order to solve the problems of slow starting speed of IF control and weak starting torque ability, the high frequency pulse voltage injection method was used to complete zero low speed starting of the motor, and combined with the effective flux method in the middle and high speed area, the position sensorless composite control strategy was formed in the full speed range. In order to achieve smooth switching between the two control methods, a hysteresis switching strategy combined with a state machine based on the speed transition region was proposed. The entire speed range was divided by the proposed strategy into the zero-low speed area, the transition area, and the medium-high speed area. When the motor entered the transition area from the medium-high speed area, the high frequency pulse voltage injection method was started in advance to stabilize the position estimation process and prepare for the switch. In order to reduce the impact of the injected high frequency voltage on the position estimation process of the effective flux method, the input and exit of the high frequency pulse voltage injection method were realized by soft switching in the speed transition zone. In order to solve the coupling problem when two position estimation methods work simultaneously in the speed transition region, a double synchronous rotating coordinate system was set up to realize the decoupled control of rotor position estimation. The effectiveness of the proposed method was verified on a three-phase permanent magnet synchronous motor.
In order to solve the problems of slow starting speed of IF control and weak starting torque ability, the high frequency pulse voltage injection method was used to complete zero low speed starting of the motor, and combined with the effective flux method in the middle and high speed area, the position sensorless composite control strategy was formed in the full speed range. In order to achieve smooth switching between the two control methods, a hysteresis switching strategy combined with a state machine based on the speed transition region was proposed. The entire speed range was divided by the proposed strategy into the zero-low speed area, the transition area, and the medium-high speed area. When the motor entered the transition area from the medium-high speed area, the high frequency pulse voltage injection method was started in advance to stabilize the position estimation process and prepare for the switch. In order to reduce the impact of the injected high frequency voltage on the position estimation process of the effective flux method, the input and exit of the high frequency pulse voltage injection method were realized by soft switching in the speed transition zone. In order to solve the coupling problem when two position estimation methods work simultaneously in the speed transition region, a double synchronous rotating coordinate system was set up to realize the decoupled control of rotor position estimation. The effectiveness of the proposed method was verified on a three-phase permanent magnet synchronous motor.
2024, 46(4):125-132.
DOI: 10.11887/j.cn.202404013
Abstract:
Aiming at the difference in the cavitation sensitivity of the control valve at different measuring points of the regulating valve body, study on the difference of cavitation induced vibration and the cavitation sensitivity of different measuring points was carried out. A test platform for cavitation-induced vibration acceleration signal acquisition of regulating valve was built, and the acceleration signals of cavitation vibration of regulating valve at multiple measuring points were simultaneously collected. Two characterization parameters, the acceleration level ratio and the gravity frequency, were proposed. Frequency spectrum of the cavitation vibration signal of regulating valve was divided by the 1/3 octave frequency spectrum, and finally the frequency band most sensitive and location of measuring points to cavitation development was obtained. Results show that the vibration signals of measuring point on the same surface of the regulating valve body are similar, and the signals on different surface are significantly different. Vibration signals of the regulating valve are anisotropic. Development of cavitation extent mainly causes the vibration intensity of the frequency band above the center frequency of 10 000 Hz to increase. It is suitable for monitoring cavitation state of control valve.
Aiming at the difference in the cavitation sensitivity of the control valve at different measuring points of the regulating valve body, study on the difference of cavitation induced vibration and the cavitation sensitivity of different measuring points was carried out. A test platform for cavitation-induced vibration acceleration signal acquisition of regulating valve was built, and the acceleration signals of cavitation vibration of regulating valve at multiple measuring points were simultaneously collected. Two characterization parameters, the acceleration level ratio and the gravity frequency, were proposed. Frequency spectrum of the cavitation vibration signal of regulating valve was divided by the 1/3 octave frequency spectrum, and finally the frequency band most sensitive and location of measuring points to cavitation development was obtained. Results show that the vibration signals of measuring point on the same surface of the regulating valve body are similar, and the signals on different surface are significantly different. Vibration signals of the regulating valve are anisotropic. Development of cavitation extent mainly causes the vibration intensity of the frequency band above the center frequency of 10 000 Hz to increase. It is suitable for monitoring cavitation state of control valve.
2024, 46(4):133-141.
DOI: 10.11887/j.cn.202404014
Abstract:
In order to achieve high-precision robust control of pneumatic cylinder motion trajectory, the mathematical model of proportional valve-controlled pneumatic cylinder system was established, and a non-linear deterministic robust controller was designed on the basis of the backstepping method, which can effectively suppress the effects of system model parameter uncertainty, unmodelled dynamics and external disturbances. The Simulink module in MATLAB was used to construct a simulation model of the pneumatic cylinder motion trajectory tracking control system. A real-time control system for pneumatic cylinder motion trajectory based on a non-linear deterministic robust controller was developed using xPC-Target in MATLAB/Simulink. The simulation results show that the designed controller is feasible. The test results show that the controller can effectively track the reference trajectory, with a maximum tracking error of 0.89 mm for a 0.3 Hz sinusoidal trajectory, which is about 2.97% of the amplitude, and 1.02 mm for a 0.4 Hz sinusoidal trajectory, which is 3.4% of the amplitude.
In order to achieve high-precision robust control of pneumatic cylinder motion trajectory, the mathematical model of proportional valve-controlled pneumatic cylinder system was established, and a non-linear deterministic robust controller was designed on the basis of the backstepping method, which can effectively suppress the effects of system model parameter uncertainty, unmodelled dynamics and external disturbances. The Simulink module in MATLAB was used to construct a simulation model of the pneumatic cylinder motion trajectory tracking control system. A real-time control system for pneumatic cylinder motion trajectory based on a non-linear deterministic robust controller was developed using xPC-Target in MATLAB/Simulink. The simulation results show that the designed controller is feasible. The test results show that the controller can effectively track the reference trajectory, with a maximum tracking error of 0.89 mm for a 0.3 Hz sinusoidal trajectory, which is about 2.97% of the amplitude, and 1.02 mm for a 0.4 Hz sinusoidal trajectory, which is 3.4% of the amplitude.
2024, 46(4):142-149.
DOI: 10.11887/j.cn.202404015
Abstract:
In order to solve the joint tracking control and vibration problem of flexible-joint space robot system in the pre-grasping stage when the position and pose are not controlled, the dynamic equations of a free-floating three-bar flexible-joint space robot system are established using the Lagrangian equation in conjunction with the principle of momentum conservation. In order to improve the equivalent stiffness of flexible-joint, a joint flexible compensation method was introduced. The flexible-joint space robot system was divided into slow and fast systems by singular perturbation theory. On this basis, a sliding mode control method with time delay estimation as the main framework was designed for the slow variable systems, while combining it with a low-pass filter to eliminate the system chattering problem caused by sliding mode control. A linear velocity difference feedback control system was designed for the fast-changing system to suppress the flexible vibration problems introduced by the flexible joints. Simulation verification demonstrates that the space robotic arm is capable of quickly and steadily tracking the desired trajectory within a limited time, confirming that the control scheme possesses good robustness and reliability.
In order to solve the joint tracking control and vibration problem of flexible-joint space robot system in the pre-grasping stage when the position and pose are not controlled, the dynamic equations of a free-floating three-bar flexible-joint space robot system are established using the Lagrangian equation in conjunction with the principle of momentum conservation. In order to improve the equivalent stiffness of flexible-joint, a joint flexible compensation method was introduced. The flexible-joint space robot system was divided into slow and fast systems by singular perturbation theory. On this basis, a sliding mode control method with time delay estimation as the main framework was designed for the slow variable systems, while combining it with a low-pass filter to eliminate the system chattering problem caused by sliding mode control. A linear velocity difference feedback control system was designed for the fast-changing system to suppress the flexible vibration problems introduced by the flexible joints. Simulation verification demonstrates that the space robotic arm is capable of quickly and steadily tracking the desired trajectory within a limited time, confirming that the control scheme possesses good robustness and reliability.
2024, 46(4):150-158.
DOI: 10.11887/j.cn.202404016
Abstract:
In view of the problem that the current evaluation of the survivability of weapons and equipment is mainly statistical and lacks physical support, in order to establish the transmission relationship between the structural parameters and the protective performance of each component, the concept of invulnerability was proposed, and the invulnerability analysis method based on the limit damage and the invulnerability characterization method based on the generalized protection time were proposed. And through the index to the quantitative mechanism of combat missions, the task-oriented invulnerability evaluation method was proposed. Driving performance invulnerability was studied as an example. Results show that:the invulnerability analysis method based on the limit damage can realize the construction of physical transfer relation from physical space to performance space; the invulnerability characterization method based on the generalized protection time can reflect the comprehensive influence of amplitude distance and difficulty degree on invulnerability; the task-oriented invulnerability evaluation method can introduce operational mission requirements into invulnerability evaluation and reduce the influence of subjective weight assignment on evaluation results. Case analysis verify the feasibility and effectiveness of the proposed method.
In view of the problem that the current evaluation of the survivability of weapons and equipment is mainly statistical and lacks physical support, in order to establish the transmission relationship between the structural parameters and the protective performance of each component, the concept of invulnerability was proposed, and the invulnerability analysis method based on the limit damage and the invulnerability characterization method based on the generalized protection time were proposed. And through the index to the quantitative mechanism of combat missions, the task-oriented invulnerability evaluation method was proposed. Driving performance invulnerability was studied as an example. Results show that:the invulnerability analysis method based on the limit damage can realize the construction of physical transfer relation from physical space to performance space; the invulnerability characterization method based on the generalized protection time can reflect the comprehensive influence of amplitude distance and difficulty degree on invulnerability; the task-oriented invulnerability evaluation method can introduce operational mission requirements into invulnerability evaluation and reduce the influence of subjective weight assignment on evaluation results. Case analysis verify the feasibility and effectiveness of the proposed method.
2024, 46(4):159-168.
DOI: 10.11887/j.cn.202404017
Abstract:
The shock isolation performance of the integrated quasi-zero stiffness isolator (as also be called “integrated isolator”) was studied. The attenuation period, oscillation frequency, maximum acceleration ratio and maximum displacement of shock response were selected as evaluation indexes, respectively. The influences of linear stiffness ratio and geometric design parameters on the shock isolation of the integrated isolator under half-sine pulse acceleration excitation were emphatically studied by using the fourth-order Runge-Kutta method. Calculation results show that the integrated isolator has better acceleration attenuation performance than the linear isolator after the shock with a long duration. The smaller outer wall height and the larger wall thickness are beneficial to improve the shock isolation performance. The relevant research can provide guidance for the engineering application of the integrated quasi-zero stiffness isolator.
The shock isolation performance of the integrated quasi-zero stiffness isolator (as also be called “integrated isolator”) was studied. The attenuation period, oscillation frequency, maximum acceleration ratio and maximum displacement of shock response were selected as evaluation indexes, respectively. The influences of linear stiffness ratio and geometric design parameters on the shock isolation of the integrated isolator under half-sine pulse acceleration excitation were emphatically studied by using the fourth-order Runge-Kutta method. Calculation results show that the integrated isolator has better acceleration attenuation performance than the linear isolator after the shock with a long duration. The smaller outer wall height and the larger wall thickness are beneficial to improve the shock isolation performance. The relevant research can provide guidance for the engineering application of the integrated quasi-zero stiffness isolator.
