CN114323526A

CN114323526A - Linear motor driven six-degree-of-freedom vibration simulation device

Info

Publication number: CN114323526A
Application number: CN202111553130.4A
Authority: CN
Inventors: 刘志华; 刘龙宇; 蔡晨光; 吕琦; 翟国栋; 夏岩
Original assignee: China University of Mining and Technology Beijing CUMTB; National Institute of Metrology
Current assignee: China University of Mining and Technology Beijing CUMTB; National Institute of Metrology
Priority date: 2021-12-17
Filing date: 2021-12-17
Publication date: 2022-04-12

Abstract

The invention discloses a six-degree-of-freedom vibration simulation device driven by a linear motor, which comprises a six-degree-of-freedom parallel mechanism, a linear motor driving mechanism and a six-degree-of-freedom measurement control system. The linear motor driving mechanism simultaneously serves as a static platform of the six-degree-of-freedom parallel mechanism, and a movable platform of the six-degree-of-freedom parallel mechanism is positioned at the upper end of the static platform and is connected with the linear motor driving mechanism through six moving branched chains. The six-degree-of-freedom parallel mechanism has the advantages of high design rigidity, strong bearing capacity and stable overall structure. The six-freedom-degree measurement control system consists of a linear grating sensor, an accelerometer and a controller, and is used for realizing real-time feedback of the motion position of the six-freedom-degree parallel mechanism and motion control of the linear motor driving device. The invention can be used for testing the dynamic response characteristic of the sensor under the complex multi-degree-of-freedom vibration excitation, solves the problem of small working space of the six-degree-of-freedom vibration simulation device in the prior art, and improves the precision, the efficiency and the range of the sensor test.

Description

Linear motor driven six-degree-of-freedom vibration simulation device

Technical Field

The invention relates to the technical field of design and test of vibration test equipment, in particular to a six-degree-of-freedom vibration simulation device driven by a linear motor.

Background

Vibration measurement is increasingly widely applied to the fields of machining, aerospace, precision machining and the like, and accordingly, the types of sensors for vibration measurement are increasing. In order to test whether the performance of the vibration sensor meets the corresponding requirements and guarantee the validity of the measured data, a vibration simulation device for vibration excitation needs to be improved. The vibration calibration device mainly aims at providing excitation acceleration for a measured vibration sensor, is usually used for providing multi-degree-of-freedom vibration excitation under different motion tracks, and is used for calibrating and verifying the functional performance of the sensor under various motion track complex vibration environments or testing the stability level and the control precision of the sensor under the complex environments.

Most of the existing six-degree-of-freedom vibration simulation devices are hydraulic vibration tables. Although the hydraulic vibration table has large bearing capacity and relatively large amplitude, the performance of a hydraulic system of the equipment is easily influenced by temperature, the requirement on oil is high, the manufacturing cost is high, and the maintenance is complex. Due to the influence of factors such as pressure pulsation of an oil pump, resonance caused by compressibility of oil, friction of a hydraulic seal and the like, the waveform distortion of the excitation acceleration provided by the hydraulic table is large. At present, small parts of electric excitation vibration tables exist in China, but the occupied space of a mechanical structure is large, the working space which can be realized by the vibration table is small, the structure of a vibration simulation device is complex, and the electric vibration tables are mostly in a medium-high frequency range and are difficult to realize low-frequency vibration excitation.

Disclosure of Invention

The invention aims to solve the problems of large space occupation of a mechanical structure, small working space of a vibration table and the like in the prior art, and provides a novel six-degree-of-freedom vibration simulation device driven by a linear motor.

The technical scheme adopted by the invention for solving the problems is as follows: provided is a six-degree-of-freedom vibration simulation device based on linear motor driving, including: the device comprises a six-degree-of-freedom parallel mechanism, a linear motor driving mechanism and a six-degree-of-freedom measurement control system. The linear motor driving mechanism simultaneously serves as a static platform of the six-degree-of-freedom parallel mechanism, and a movable platform of the six-degree-of-freedom parallel mechanism is positioned at the upper end of the static platform and is connected with the linear motor driving mechanism through six moving branched chains. The six-degree-of-freedom measurement control system consists of a linear grating sensor, an accelerometer and a controller, wherein the linear grating sensor and the accelerometer are respectively positioned at the bottom of the linear motor driving mechanism and on the side surface of the workbench.

In a preferred embodiment, the six-degree-of-freedom parallel mechanism comprises a movable platform (1) and a movable branched chain (2). The movable platform (1) is a Y-shaped platform, is used for installing a sensor to be tested and provides multi-degree-of-freedom vibration excitation for the sensor to be tested. The number of the moving branched chains (2) is six, and the moving branched chains are composed of a moving platform spherical hinge (5), a connecting rod (6) and a static platform spherical hinge (7). The connecting rod (6) of the moving branched chain (2) is a rigid body, has no elasticity and strong bearing capacity. The movable parts of the moving branch chains (2) are a moving platform spherical hinge (5) and a static platform spherical hinge (7), and the moving branch chains are simple and stable in structure, small in accumulative error and good in transmission performance. The top end of the linear motor driving mechanism workbench (9) is fixedly connected with the supporting platform mounting seat (17), and the static platform spherical hinge (7) is fixedly mounted on the upper surface of the supporting platform mounting seat (17). The lower surface of the movable platform (1) is fixedly connected with the movable platform mounting seat (18), every two movable platform spherical hinges (5) are in a group and fixedly mounted on the movable platform mounting seat (18), and the rotation of the six-degree-of-freedom parallel mechanism can reach a larger angle. The moving branch chains (2) are grouped in pairs, and the movable platform (1) is connected with the linear motor driving mechanism workbench (9) through the movable platform spherical hinge (5) and the static platform spherical hinge (7), so that the movable platform (1) of the six-degree-of-freedom parallel mechanism can output different positions and postures.

In a preferred embodiment, the linear motor driving mechanism comprises a linear motor (4), a base (8), a workbench (9), a guide rail (12) and an air bearing (13). The number of the linear motors (4) is six, and every two linear motors are arranged on the same base (8) in parallel and are uniformly distributed at intervals of 120 degrees. The guide rail (12) is fixed on the base (8) in parallel, the air bearing (13) is arranged on the guide rail (12), and the top end of the air bearing (13) is matched with the bottom end of the workbench (9) so as to reduce friction and noise and enable the movement to be more stable. The linear motor is a coreless linear motor, a rotor (secondary) of the motor (10) is fixed on the lower surface of the workbench (9), the magnetic track (11) is fixed at the bottom end of the base (8), and the stators are uniformly distributed on two sides of a groove of the magnetic track (11). When alternating current is introduced into a stator (primary) winding, a traveling wave magnetic field is generated in an air gap, the mover (secondary) (10) generates induced electromotive force under the cutting of the traveling wave magnetic field and generates current, the current interacts with the magnetic field in the air gap to generate electromagnetic thrust, and the mover (secondary) (10) moves linearly under the action of the thrust, so that the workbench (9) moves linearly on the guide rail (12).

In a preferred embodiment, the six-degree-of-freedom measurement control system consists of a linear grating sensor (3), an accelerometer (20) and a controller (21). The linear grating sensor (3) consists of a grating ruler (14) and a grating reading head (15). The grating ruler (14) is installed in base (8) bottom, the side at workstation mounting panel (16) is installed in grating reading head (15), and controller (21) make linear motor motion to linear motor actuating mechanism sending current signal, and grating reading head (15) obtain real-time displacement information along with workstation (9) motion, and controller (21) accept the displacement feedback of linear grating sensor (3). The accelerometer (20) is arranged on the side surface of the workbench (9) and has consistent movement characteristics with the workbench (9). The motion state of the workbench (9) is measured by the accelerometer (20), and an acceleration signal measured by the accelerometer (20) is transmitted back to the computer through the signal conditioner for real-time analysis, processing and display. The six-degree-of-freedom measurement control system adopts a mode of fusing low-frequency displacement measurement of a linear grating sensor and high-frequency acceleration measurement of an accelerometer to realize motion feedback of a wide frequency band.

Compared with the prior art, the invention provides a six-degree-of-freedom vibration simulation device driven by a linear motor, which has the following advantages:

(1) compared with the existing motion platform, the six-degree-of-freedom vibration simulation device driven by the linear motor adopts a direct driving mode, transmits vibration to the terminal platform through the parallel mechanism, effectively eliminates the flexible influence of indirect transmission parts, has high rigidity of the whole system, and can generate high-frequency motion.

(2) Compared with the existing vibration simulation device, the six-degree-of-freedom vibration simulation device driven by the linear motor has the advantages that the linear motor driving mechanism can realize large-range motion, high-frequency vibration excitation can be generated in a large working space range, and the self-weight influence can be eliminated without an auxiliary balance mechanism.

(3) According to the six-degree-of-freedom vibration simulation device driven by the linear motor, the six-degree-of-freedom measurement control system adopts a mode of combining low-frequency displacement measurement of the linear grating sensor and high-frequency acceleration measurement of the accelerometer, so that broadband motion feedback control is ensured, and the bandwidth of a servo control system is ensured. Drawings

FIG. 1 is a schematic diagram of a linear motor driven six degree of freedom parallel mechanism arrangement in accordance with one embodiment of the present invention;

FIG. 2 is an enlarged schematic view of a linear motor drive mechanism of a linear motor driven six degree of freedom vibration simulation apparatus according to the present invention;

fig. 3 is a schematic diagram of a six-degree-of-freedom measurement control system of a linear motor driven six-degree-of-freedom vibration simulation apparatus according to the present invention.

In the figure: 1. the device comprises a movable platform 2, a movable branch chain 3, a linear grating sensor 4, a linear motor 5, a movable platform spherical hinge 6, a connecting rod 7, a static platform spherical hinge 8, a base 9, a workbench 10, a mover 11, a magnetic track 12, a guide rail 13, an air bearing 14, a grating ruler 15, a grating reading head 16, a workbench mounting plate 17, a supporting platform mounting seat 18, a movable platform mounting seat 19, a guide rail upper mounting plate 20, an accelerometer 21 and a controller

Detailed Description

To further illustrate the technical features, objects, and advantages of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings. Wherein like parts are given like reference numerals.

Fig. 1 is a schematic structural diagram of a six-degree-of-freedom parallel mechanism of a six-degree-of-freedom vibration simulation device, and the six-degree-of-freedom parallel mechanism comprises a movable platform 1 and a movable branched chain 2. The movable platform 1 is a Y-shaped platform and is used for installing a sensor to be tested and providing multi-degree-of-freedom vibration excitation for the sensor. The number of the moving branched chains 2 is six, and the moving branched chains are composed of a moving platform spherical hinge 5, a connecting rod 6 and a static platform spherical hinge 7. The connecting rod 6 of the moving branched chain 2 is a rigid body and has strong bearing capacity. The connecting rod 6 has no elasticity, the rotational inertia of the branched chain is reduced, the motion inertia of the six-degree-of-freedom parallel mechanism is reduced, and the whole structure is more stable. The movable part of the moving branch chain is a moving platform spherical hinge 5 and a static platform spherical hinge 7, the spherical hinge is an SRJ spherical bearing, and compared with other universal hinges, the SRJ spherical bearing has the characteristics of high rigidity, miniaturization, high precision and excellent vibration attenuation performance. The top end of the workbench 9 is fixedly connected with the supporting platform mounting seat 17 through an inner hexagon screw, and the static platform spherical hinge 7 is fixedly mounted on the upper surface of the supporting platform mounting seat 17 through the inner hexagon screw, so that the movable platform 1 of the six-degree-of-freedom parallel mechanism can output different positions and postures. The lower surface of the movable platform 1 is fixedly connected with the movable platform mounting seat 18 through the hexagon socket head cap screws, every two movable platform spherical hinges 5 form a group and are fixedly mounted on the movable platform mounting seat 18, and the rotation of the six-degree-of-freedom parallel mechanism can reach a larger angle. The six-degree-of-freedom parallel mechanism is simple in overall structure design, small in accumulated error and good in transmission performance.

Fig. 2 is an enlarged schematic view of a linear motor driving mechanism of a six-degree-of-freedom vibration simulation apparatus, where the linear motor driving mechanism includes a grating 3, a base 8, a table 9, a mover 10, a magnetic track 11, a guide rail 12, an air bearing 13, and a guide rail upper mounting plate 19. The number of the linear motors is six, and every two linear motors are arranged on the same base (8) in parallel and are uniformly distributed at intervals of 120 degrees. The linear motor is provided with the air bearing 13, mechanical contact, friction and noise are not generated during movement, abrasion of transmission parts is reduced, and the overall efficiency of the device is greatly improved. Two sides of the base 8 are provided with 4 mounting holes, the axial side surface of the base 8 is provided with lugs, the guide rail 12 is mounted on the mounting holes of the lugs on the axial side surface of the base 8, and the mounting plate 19 on the guide rail is fixedly mounted on the axial side surface of the base 8 through hexagon socket head cap screws and used for fixing the guide rail 12. Every two air bearings 13 are arranged on each guide rail 12 in a group, and the workbench 9 is fixedly arranged on the upper surface of each group of air bearings 13. The direct-drive linear motor is a coreless linear motor, and the linear motor is not provided with an iron core or a slot for winding a coil, so that the direct-drive linear motor is light in weight, and the mutual attraction between a coil group and a magnetic circuit does not exist. The friction force of the bearing is small, and the uniform motion can be ensured under the low-speed condition. The active cell 10 of motor is fixed mounting in the lower surface of workstation 9, and magnetic track 11 is fixed in the bottom of base 8, and the even both sides in the recess of magnetic track 11 of distributing of stator (elementary). When alternating current is introduced into a stator (primary) winding, a traveling wave magnetic field is generated in an air gap, the rotor (secondary) 10 generates induced electromotive force and generates current under the cutting of the traveling wave magnetic field, the current and the magnetic field in the air gap interact to generate electromagnetic thrust, and the rotor (secondary) 10 moves linearly under the thrust action, so that the workbench (9) moves linearly on the guide rail (12). Choose linear electric motor for use as the drive, can realize high-speed linear motion, and the structure obtains simplifying, and dynamic response and positioning accuracy obtain promoting, and the reliability of device improves, practices thrift manufacturing cost simultaneously, and manufacturing and later maintenance are more simple convenient.

Fig. 3 is a schematic diagram of a six-degree-of-freedom measurement control system of a six-degree-of-freedom vibration simulation apparatus. The six-degree-of-freedom measurement control system consists of a linear grating sensor 3, an accelerometer 20 and a controller 21. The linear grating sensor 3 consists of a grating ruler 14 and a grating reading head 15. The bottom of the linear motor 4 is provided with a grating ruler 14, the workbench mounting plate 16 is fixedly mounted on the side surface of the workbench 9 through an inner hexagon bolt, and the grating reading head 15 is fixedly mounted at the bottom of the workbench mounting plate 16 and is opposite to the grating ruler 14. The controller 21 sends a current signal to the linear motor driving mechanism, the linear motor moves, the grating reading head 15 moves along with the workbench 9 to obtain real-time displacement information, and the controller 21 receives the displacement feedback of the linear grating sensor 3. The accelerometer 20 is mounted on the side of the table 9 and has a motion characteristic consistent with that of the table 9. The invention selects the PMAC card as the controller, which comprises a control algorithm capable of realizing self-definition. The D/a converter is used as an output channel of the controller 21, is connected with the linear motor driving mechanism, and converts continuous virtual signals into discrete digital signals to realize automatic control of the system. The motion controller sends DAC analog signals to drive the linear motor to do linear motion, and vibration acceleration signals of the workbench 9 are collected through the accelerometer 20. The a/D converter serves as a signal conditioner, converts the analog signal output by the accelerometer 20 into a digital signal, and transmits the digital signal back to the computer for real-time analysis, processing and display by the computer. The six-degree-of-freedom measurement control system adopts a mode of fusing low-frequency displacement measurement of the linear grating sensor 3 and high-frequency acceleration measurement of the accelerometer 20, and realizes full coverage of broadband motion measurement. The six-degree-of-freedom measurement control system can ensure the stability of measurement, reduce the measurement error, meet the characteristics of static positioning calibration, uniform calibration and high-frequency vibration calibration of the device, and improve the response capability and the disturbance resistance of the system.

The above description is a detailed description of an example embodiment of the invention and is not intended to limit the invention in any way. The invention is capable of many modifications, improvements and adaptations by those skilled in the art. Accordingly, the scope of the invention should be determined from the following claims.

Claims

1. The utility model provides a six degree of freedom vibration analogue means of linear electric motor driven which characterized in that: the device comprises a six-degree-of-freedom parallel mechanism, a linear motor driving mechanism and a six-degree-of-freedom measurement control system; the linear motor driving mechanism simultaneously serves as a static platform of the six-degree-of-freedom parallel mechanism, and a movable platform of the six-degree-of-freedom parallel mechanism is positioned at the upper end of the static platform and is connected with the linear motor driving mechanism through six moving branched chains; the six-degree-of-freedom measurement control system consists of a linear grating sensor, an accelerometer and a controller, wherein the linear grating sensor and the accelerometer are respectively positioned at the bottom of the linear motor driving mechanism and on the side surface of the workbench.

2. The linear motor driven six degree of freedom vibration simulation apparatus of claim 1, wherein: the six-degree-of-freedom parallel mechanism comprises a movable platform (1) and a moving branched chain (2); the movable platform (1) is a Y-shaped platform, is used for installing a sensor to be tested and provides multi-degree-of-freedom vibration excitation for the sensor to be tested; the number of the moving branched chains (2) is six, and the moving branched chains are composed of a moving platform spherical hinge (5), a connecting rod (6) and a static platform spherical hinge (7); the connecting rod (6) of the moving branched chain (2) is a rigid body; the movable part of the movable branched chain (2) is a movable platform spherical hinge (5) and a static platform spherical hinge (7); the top end of the linear motor driving mechanism workbench (9) is fixedly connected with the supporting platform mounting seat (17), and the static platform spherical hinge (7) is fixedly arranged on the upper surface of the supporting platform mounting seat (17); the lower surface of the movable platform (1) is fixedly connected with a movable platform mounting seat (18), every two movable platform spherical hinges (5) are in a group and fixedly mounted on the movable platform mounting seat (18), so that the rotation of the six-degree-of-freedom parallel mechanism can reach a larger angle; the moving branch chains (2) are grouped in pairs, and the movable platform (1) is connected with the linear motor driving mechanism workbench (9) through the movable platform spherical hinge (5) and the static platform spherical hinge (7), so that the movable platform (1) of the six-degree-of-freedom parallel mechanism can output different positions and postures.

3. The linear motor driven six degree of freedom vibration simulation apparatus of claim 2, wherein: the linear motor driving mechanism comprises a linear motor (4), a base (8), a workbench (9), a guide rail (12) and an air bearing (13); the number of the linear motors (4) is six, and every two linear motors are arranged on the same base (8) in parallel and are uniformly distributed at intervals of 120 degrees; the guide rail (12) is fixed on the base (8) in parallel, the air bearing (13) is arranged on the guide rail (12), and the top end of the air bearing (13) is matched with the bottom end of the workbench (9); the linear motor is a coreless linear motor, a rotor (10) of the motor is fixed on the lower surface of the workbench (9), the magnetic track (11) is fixed at the bottom end of the base (8), and the stators are uniformly distributed on two sides of the groove of the magnetic track (11); when alternating current is introduced into the stator winding, a traveling wave magnetic field is generated in the air gap, the rotor (10) generates induced electromotive force and generates current under the cutting of the traveling wave magnetic field, the current and the magnetic field in the air gap interact to generate electromagnetic thrust, and the rotor (10) moves linearly under the action of the thrust, so that the workbench (9) moves linearly on the guide rail (12).

4. A linear motor driven six degree of freedom vibration simulator as defined in claim 3 in which: the six-degree-of-freedom measurement control system consists of a linear grating sensor (3), an accelerometer (20) and a controller; the linear grating sensor (3) consists of a grating ruler (14) and a grating reading head (15); the grating ruler (14) is installed at the bottom of the base (8), the grating reading head (15) is installed on the side face of the workbench installation plate (16), the controller (21) sends a current signal to the linear motor driving mechanism to enable the linear motor to move, the grating reading head (15) moves along with the workbench (9) to obtain real-time displacement information, and the controller (21) receives displacement feedback of the linear grating sensor (3); the accelerometer (20) is arranged on the side surface of the workbench (9) and has consistent motion characteristics with the workbench (9); the motion state of the workbench (9) is measured by the accelerometer (20), and an acceleration signal measured by the accelerometer (20) is transmitted back to the computer through the signal conditioner for real-time analysis, processing and display; the six-degree-of-freedom measurement control system adopts a mode of fusing low-frequency displacement measurement of a linear grating sensor and high-frequency acceleration measurement of an accelerometer to realize motion feedback of a wide frequency band.