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

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

A linear motor-driven six-degree-of-freedom vibration simulation device

technical field

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

Background technique

Vibration measurement is more and more widely used in the fields of machining, aerospace, precision machining, etc. Correspondingly, there are more and more types of sensors used for vibration measurement. In order to test whether the performance of the vibration sensor meets the corresponding requirements and ensure the validity of the measurement data, it is necessary to improve the vibration simulation device for vibration excitation. The main task of the vibration calibration device is to provide excitation acceleration for the vibration sensor under test. It is often used to provide multi-degree-of-freedom vibration excitation under different motion trajectories, to calibrate and verify the functional performance of sensors in complex vibration environments of various motion trajectories, or to test Its stability level and control accuracy in complex environment.

Most of the existing six-degree-of-freedom vibration simulation devices are hydraulic vibration tables. Although the hydraulic vibration table has a large bearing capacity and a relatively large amplitude, the performance of the hydraulic system of this equipment is easily affected by temperature, requires high oil, and is expensive and complicated to maintain. Due to the influence of the pressure pulsation of the oil pump, the resonance caused by the compressibility of the oil, and the friction of the hydraulic seal, the excitation acceleration waveform provided by the hydraulic table is greatly distorted. At present, there are also a small number of electro-excited vibration tables in China, but the mechanical structure occupies a large space, the working space that the vibration table can achieve is small, the structure of the vibration simulation device is complex, and most of the electro-dynamic vibration tables are in the medium and high frequency range, which is difficult to achieve. Low frequency vibration excitation.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the problems in the prior art, such as the large space occupied by the mechanical structure and the small working space of the vibrating table, and provide a novel six-degree-of-freedom vibration simulation device driven by a linear motor.

The technical solution adopted by the present invention to solve the above problems is to provide a six-degree-of-freedom vibration simulation device driven by a linear motor, including a six-degree-of-freedom parallel mechanism, a linear motor driving mechanism, and a six-degree-of-freedom measurement control system. The linear motor drive mechanism simultaneously serves as the static platform of the six-degree-of-freedom parallel mechanism, and the moving platform of the six-degree-of-freedom parallel mechanism is located at the upper end of the static platform and is connected to the linear motor drive mechanism through six motion branches. The six-degree-of-freedom measurement control system consists of a linear grating sensor, an accelerometer and a controller. The linear grating sensor and the accelerometer are located at the bottom of the linear motor drive mechanism and the side surface of the worktable respectively.

In a preferred embodiment, the six-degree-of-freedom parallel mechanism includes a moving platform (1) and a moving branch chain (2). The moving platform (1) is a Y-shaped platform, which is used to install the sensor under test and provide it with multi-degree-of-freedom vibration excitation. The number of the moving branches (2) is six, and is 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 branch chain (2) is a rigid body, has no flexibility, and has strong bearing capacity. The movable parts of the moving branch chain (2) are the moving platform spherical hinge (5) and the static platform spherical hinge (7), which are simple in structure, stable, reduce the accumulated error, and have good transmission performance. The top of the linear motor drive mechanism worktable (9) is fixedly connected with the support platform mounting seat (17), and the static platform ball hinge (7) is fixedly mounted on the upper surface of the support platform mounting seat (17). The lower surface of the moving platform (1) is fixedly connected with the moving platform mounting seat (18), and every two moving platform ball hinges (5) are a group, which is fixedly installed on the moving platform mounting seat (18), so that the six free The rotation of the parallel mechanism can reach larger angles. The moving branches (2) are set in two groups, and the moving platform (1) and the linear motor drive mechanism worktable (9) are connected through the moving platform spherical hinge (5) and the static platform spherical hinge (7), so that six degrees of freedom are achieved. The moving platform (1) of the parallel mechanism can output different positions and attitudes.

In a preferred embodiment, the linear motor driving mechanism includes a linear motor (4), a base (8), a worktable (9), a guide rail (12), and an air bearing (13). The number of the linear motors (4) is six, and the linear motors (4) are installed in parallel on the same base (8) in pairs, and are evenly distributed at 120° intervals. The guide rail (12) is fixed on the base (8) in parallel, and the air bearing (13) is arranged on the guide rail (12). Cooperate to reduce friction, reduce noise, and make the movement more stable. The linear motor is an ironless linear motor, the mover (secondary) (10) of the motor is fixed on the lower surface of the worktable (9), the magnetic track (11) is fixed on the bottom end of the base (8), and the stator Evenly distributed on both sides of the groove of the magnetic track (11). When the stator (primary) winding is supplied with alternating current, a traveling wave magnetic field is generated in the air gap, and the mover (secondary) (10) generates an induced electromotive force and a current under the cutting of the traveling wave magnetic field, and the current is related to the air gap in the air gap. The interaction of the magnetic fields generates electromagnetic thrust, and the mover (secondary) (10) performs linear motion under the action of the thrust, so that the worktable (9) performs linear motion 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) is composed of a grating ruler (14) and a grating reading head (15). The grating ruler (14) is mounted on the bottom of the base (8), the grating reading head (15) is mounted on the side of the worktable mounting plate (16), and the controller (21) sends a current signal to the linear motor drive mechanism to make the linear motor drive mechanism. The linear motor moves, the grating reading head (15) moves with the worktable (9) to obtain real-time displacement information, and the controller (21) accepts the displacement feedback of the linear grating sensor (3). The accelerometer (20) is installed on the side surface of the workbench (9), and has the same motion characteristics as the workbench (9). The motion state of the workbench (9) is measured by the accelerometer (20), and the acceleration signal measured by the accelerometer (20) is sent back to the computer through the signal conditioner for real-time analysis, processing and display. The six-degree-of-freedom measurement and control system adopts the integration of the low-frequency displacement measurement of the linear grating sensor and the high-frequency acceleration measurement of the accelerometer to achieve wide-band motion feedback.

Compared with the prior art, the present invention provides a linear motor-driven six-degree-of-freedom vibration simulation device, 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 drive method, and transmits the vibration to the terminal platform through a parallel mechanism, which effectively eliminates the influence of the flexibility of the indirect transmission components. The mechanical system has high stiffness and can generate high-frequency motion.

(2) The linear motor-driven six-degree-of-freedom vibration simulation device, compared with the existing vibration simulation device, the linear motor drive mechanism can realize a wide range of motion, and can generate high-frequency vibration excitation in a large working space without assistance The balance mechanism eliminates the influence of self-weight.

(3) The six-degree-of-freedom vibration simulation device driven by the linear motor, the six-degree-of-freedom measurement control system adopts the method of integrating the low-frequency displacement measurement of the linear grating sensor and the high-frequency acceleration measurement of the accelerometer to ensure broadband motion feedback control and servo control. system bandwidth. Description of drawings

1 is a schematic structural diagram of a six-degree-of-freedom parallel mechanism device driven by a linear motor according to a specific implementation of the present invention;

2 is an enlarged schematic view of the linear motor drive mechanism of the linear motor-driven six-degree-of-freedom vibration simulation device according to the present invention;

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

In the figure: 1, moving platform 2, moving branch 3, linear grating sensor 4, linear motor 5, moving platform ball hinge 6, connecting rod 7, static platform ball hinge 8, base 9, worktable 10, mover 11 , magnetic track 12, guide rail 13, air bearing 14, grating ruler 15, grating reading head 16, worktable mounting plate 17, support platform mounting seat 18, moving platform mounting seat 19, guide rail mounting plate 20, accelerometer 21, controller

Detailed ways

In order to further illustrate the technical features, objectives and advantages of the present invention, the specific embodiments of the present invention will now be described with reference to the accompanying drawings. Among them, the same parts have the same reference numbers.

FIG. 1 is a schematic structural diagram of a six-degree-of-freedom parallel mechanism of a six-degree-of-freedom vibration simulation device. The six-degree-of-freedom parallel mechanism includes a moving platform 1 and a moving branch chain 2 . The moving platform 1 is a Y-shaped platform, which is used to install the sensor under test and provide it with multi-degree-of-freedom vibration excitation. The number of the moving branches 2 is six, which is 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 motion branch chain 2 is a rigid body with strong bearing capacity. The connecting rod 6 has no telescopicity, which reduces the moment of inertia of the branch chain, reduces the moment of inertia of the six-degree-of-freedom parallel mechanism, and makes the overall structure more stable. The movable parts of the moving chain are the ball hinge 5 of the moving platform and the ball hinge 7 of the static platform. The spherical hinge adopts SRJ spherical bearing. Compared with other universal hinges, the SRJ spherical bearing has high rigidity, miniaturization, high precision and vibration damping performance. Excellent features. The top of the worktable 9 is fixedly connected with the support platform mounting seat 17 by hexagon socket head screws, and the static platform ball hinge 7 is fixedly installed on the upper surface of the support platform mounting seat 17 by the socket head socket screws, so that the moving platform of the six-degree-of-freedom parallel mechanism is 1 can output different positions and poses. The lower surface of the moving platform 1 and the moving platform mounting seat 18 are fixedly connected by hexagon socket screws, and every two moving platform ball hinges 5 are a group, which is fixedly installed on the moving platform mounting seat 18, so that the six-degree-of-freedom parallel mechanism is connected. Rotation enables larger angles. The overall structure of the six-degree-of-freedom parallel mechanism is simple in design, with small cumulative error and good transmission performance.

FIG. 2 is an enlarged schematic view of the linear motor drive mechanism of the six-degree-of-freedom vibration simulation device. The linear motor drive mechanism includes a grating 3, a base 8, a worktable 9, a mover 10, a magnetic track 11, a guide rail 12, and an air bearing. 13 and the mounting plate 19 on the guide rail. The number of the linear motors is six, and the linear motors are installed in parallel on the same base (8) in two groups and evenly distributed at 120° intervals. The linear motor is provided with an air bearing 13, which does not generate mechanical contact, friction and noise during movement, reduces the wear of transmission parts, and greatly improves the overall efficiency of the device. There are 4 mounting holes on both sides of the base 8, lugs are provided on the axial side of the base 8, the guide rail 12 is installed on the mounting holes of the lugs on the axial side of the base 8, and the mounting plate 19 on the guide rail passes through the socket head cap screws. It is fixedly installed on the axial side of the base 8 for fixing the guide rail 12 . Each two air bearing 13 is installed on each guide rail 12 as a group, and the worktable 9 is fixedly installed on the upper surface of each air bearing 13 . The direct drive linear motor uses an ironless linear motor. This type of linear motor has no iron core or slot for winding the coil, and is light in weight, and there is no mutual attraction between the coil group and the magnetic circuit. The friction of the bearing is small, which can ensure uniform motion under low speed conditions. The mover 10 of the motor is fixedly installed on the lower surface of the table 9 , the magnetic track 11 is fixed on the bottom end of the base 8 , and the stators (primary) are evenly distributed on both sides of the groove of the magnetic track 11 . When the stator (primary) winding is supplied with alternating current, a traveling wave magnetic field is generated in the air gap, and the mover (secondary) 10 generates an induced electromotive force and a current under the cutting of the traveling wave magnetic field, and the current interacts with the magnetic field in the air gap. The action generates electromagnetic thrust, and the mover (secondary) 10 performs linear motion under the action of thrust, so that the worktable (9) performs linear motion on the guide rail (12). Using a linear motor as the drive can realize high-speed linear motion, and the structure is simplified, the dynamic response and positioning accuracy are improved, the reliability of the device is improved, and the production cost is saved at the same time, and the manufacturing and post-maintenance are simpler and more convenient.

FIG. 3 is a schematic diagram of a six-degree-of-freedom measurement and control system of the six-degree-of-freedom vibration simulation device. The six-degree-of-freedom measurement control system is composed of a linear grating sensor 3 , an accelerometer 20 and a controller 21 . The linear grating sensor 3 is composed of a grating ruler 14 and a grating reading head 15 . The grating ruler 14 is installed on the bottom of the linear motor 4 , the worktable mounting plate 16 is fixedly installed on the side of the worktable 9 by hexagon socket head bolts, and the grating reading head 15 is fixedly installed on the bottom of the worktable mounting plate 16 , facing the grating ruler 14 . The controller 21 sends a current signal to the linear motor drive mechanism, which is the movement of the linear motor. The grating reading head 15 moves with the worktable 9 to obtain real-time displacement information. The accelerometer 20 is installed on the side of the workbench 9 and has the same motion characteristics as the workbench 9 . The present invention selects the PMAC card as the controller, which includes a control algorithm capable of realizing self-definition. As the output channel of the controller 21, the D/A converter is connected with the linear motor drive mechanism, and converts continuous virtual signals into discrete digital signals to realize automatic control of the system. The motion controller sends a DAC analog signal to drive the linear motor to perform linear motion, and the vibration acceleration signal of the worktable 9 is collected by the accelerometer 20 . As a signal conditioner, the A/D converter converts the analog signal output by the accelerometer 20 into a digital signal and transmits it back to the computer for real-time analysis, processing and display by the computer. The six-degree-of-freedom measurement and control system adopts the integration of linear grating sensor 3 low-frequency displacement measurement and accelerometer 20 high-frequency acceleration measurement to achieve full coverage of broadband motion measurement. The six-degree-of-freedom measurement control system can ensure the stability of the 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 system responsiveness and anti-disturbance performance.

The above description is a detailed introduction of the embodiments of the present invention, and is not intended to limit the present invention in any form. Those skilled in the art can make a series of optimizations, improvements and modifications on the basis of the present invention. Accordingly, the scope of protection of the present invention should be defined by the appended claims.

Claims (4)

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.

Images