Six-degree-of-freedom large-load low-frequency excitation platform based on air spring

Abstract

The application belongs to the technical field of mechanical dynamics, and discloses a six-degree-of-freedom large-load low-frequency excitation platform based on an air spring, which comprises an exciter, wherein the exciter comprises an upper end plate, a base and a horizontal swing mechanism, the horizontal swing mechanism is partially arranged in the base, and the upper end plate is connected to the base; the base and the horizontal swing mechanism jointly form an air spring, and the air spring is arranged opposite to the upper end plate; the upper end plate is used for connecting a load; the excitation platform makes the air spring deform by introducing air into the air spring to float the upper end plate, and then floats the load. The application overcomes the influence of the target load gravity on excitation through the air spring, reduces the stiffness in the vertical direction, makes the motor provide the excitation force of full frequency band and controllable size for the load, and has good low-frequency excitation effect.

Description

Technical Field

[0001] This invention belongs to the field of mechanical dynamics, and more specifically, relates to a six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs. Background Technology

[0002] With the rapid development of the IC manufacturing industry, the processing and usage precision of various high-end manufacturing equipment has entered the nanometer / sub-nanometer level, making the impact of various vibrations increasingly prominent. How to isolate and control micro-vibrations in precision manufacturing equipment such as lithography machines has become a research hotspot and challenge. Research on high-performance precision vibration isolation technology will be a crucial support and fundamental guarantee for the future development of the high-end manufacturing equipment industry.

[0003] Research on precision vibration isolation technology can be broadly divided into three stages: design, fabrication, and testing. The main task of the testing stage is to apply effective external excitation to the entire vibration isolation platform and load, accurately simulating the working environment of the application equipment, and ultimately verifying the performance and stability of the vibration isolation system. Therefore, how to apply effective and accurate working excitation to the vibration isolation system has become an important aspect of precision vibration isolation technology research.

[0004] Currently, most vibration damping systems on the market use a distributed single-point excitation method. This method works by evenly distributing single-point vibrators around the vibration damping system. Each vibrator generates an excitation force through its own vibration, which is then transmitted to the base of the vibration damping system. While direct and effective, this method requires overcoming the influence of gravity on the vibration damping system and can generally only provide excitation forces above 2Hz. It is often ineffective for excitations below 2Hz. Furthermore, this method only achieves unidirectional excitation through simple coordination between individual vibrators; changing the excitation direction requires adjusting the installation orientation. Additionally, there are some bus-controlled six-degree-of-freedom vibration platforms that can provide six-degree-of-freedom excitation for systems placed on the platform. However, these platforms rely entirely on motors for power output and cannot meet the excitation requirements of high-load vibration damping systems. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a six-degree-of-freedom large-load low-frequency excitation platform based on air springs. It overcomes the influence of the target load gravity on the excitation by using air springs, reduces the stiffness in the vertical direction, and enables the motor to provide the load with a full-frequency excitation force with controllable magnitude, and has a good low-frequency excitation effect.

[0006] To achieve the above objectives, according to one aspect of the present invention, a six-degree-of-freedom high-load low-frequency vibration platform based on an air spring is provided. The vibration platform includes a vibrator, which includes an upper end plate, a base, and a horizontal pendulum mechanism. The horizontal pendulum mechanism is partially disposed within the base, and the upper end plate is connected to the base. The base and the horizontal pendulum mechanism together form an air spring, which is disposed opposite to the upper end plate. The upper end plate is used to connect a load.

[0007] The vibration platform causes the air spring to deform by introducing air into it, thereby leviting the upper end plate and the load.

[0008] Furthermore, the excitation platform also includes an air pipe and a pressure valve. The pressure valve is connected to the air spring through the air pipe, and the pressure inside the air spring is controlled by the pressure valve to match loads of different masses.

[0009] Furthermore, the excitation platform includes a controller, a horizontal Lorentz motor, and a vertical Lorentz motor. The controller is connected to the horizontal and vertical Lorentz motors respectively. The horizontal and vertical Lorentz motors are respectively arranged on the outer periphery of the base in the horizontal and vertical directions. The magnets and movers of the motors are respectively fixed to the lower surface of the upper end plate and the outer periphery of the base. The horizontal and vertical Lorentz motors are used to provide excitation forces in various directions of the excitation platform. The controller is used to calculate the output force of each motor of the exciter according to the load's requirements for the magnitude and direction of the excitation force during operation, and to achieve individual excitation of the load in six degrees of freedom by decoupling the motor output at the center of mass.

[0010] Furthermore, the output matrix of the motor of the excitation platform is as follows:

[0011]

[0012] In the formula, the subscript letter h represents the horizontal direction, v represents the vertical direction, and the subscript number indicates the exciter number; ∑h i =h1+h2+h3; p xy =x1y2-x2y1-x1y3+x3y1+

[0013] x2y3-x3y2; Establish a global coordinate system ∑ based on the load centroid in equilibrium state. O Define the load centroid C in ∑ O The displacement of the six degrees of freedom is r, and the excitation force acting on the center of mass of the load is F. c Therefore, we have:

[0014] r = [xyz α β γ]T (1)

[0015] F c =[F x F y F z M x M y M z ] T (2)

[0016] Define o pi The connection point between the i-th exciter and the support platform is in ∑ O The coordinates in (o) pi )0 represents the point in ∑ O The initial position in q i Then the point is in ∑ O The displacement in the middle, therefore:

[0017] q i =[x i y i z i ] = o pi -(o pi )0, i = 1, 2, 3.

[0018] Furthermore, the controller converts the excitation force intended to act on the load center of mass into individual output forces of the motors in each direction through the output matrix, thereby achieving individual excitation in six degrees of freedom directions.

[0019] Furthermore, the excitation platform also includes a horizontal eddy current displacement sensor and a vertical eddy current displacement sensor. Multiple horizontal and vertical eddy current displacement sensors are respectively arranged on the motor housing and the base in the horizontal and vertical directions. The horizontal and vertical eddy current displacement sensors are used to collect the position information of the load in different directions and feed the displacement signal back to the controller. The controller is used to control the motors accordingly based on the received displacement signals to maintain the output of each motor at the required value.

[0020] Furthermore, the base is basically barrel-shaped and has a receiving cavity for receiving the horizontal swing mechanism; the open end of the base extends toward its own central axis with a boss, and the boss has a first through hole; the horizontal swing mechanism is disposed in the receiving cavity and is connected to the boss and the upper end plate.

[0021] Furthermore, the horizontal swing mechanism includes a support plate, an inner pressure plate, a rubber mold, and an outer pressure plate. The support plate is a T-shaped rotating body with a first receiving hole that penetrates the plate body. The upper surface of the plate body is coplanar with the surface of the boss. The rubber mold is annular, with its inner and outer edges respectively disposed on the plate body and the boss. The inner pressure plate is disposed on the plate body and presses against the inner edge of the rubber mold. The outer pressure plate is disposed on the boss and presses against the outer edge of the rubber mold.

[0022] Furthermore, the horizontal swing mechanism also includes three tie rods and a connecting column. The inner pressure plate has a second through hole. The connecting column is stepped, with one end passing through the second through hole and connected to the upper end plate, and the other end located in the receiving hole. One end of the tie rod is connected to the inner pressure plate, and the other end is connected to the step of the connecting column.

[0023] Furthermore, the number of the pull rods is three, and the three pull rods are evenly arranged around the second through hole; the pull rods are flexible metal rods, and the three pull rods are connected in parallel to form a pendulum mechanism.

[0024] In summary, compared with the prior art, the six-degree-of-freedom high-load low-frequency excitation platform based on air springs provided by the present invention has the following beneficial effects:

[0025] 1. The excitation platform overcomes the influence of the target load gravity on the excitation by means of an air spring, reduces the stiffness in the vertical direction, and enables the motor to provide the load with a full-frequency and controllable excitation force, and has a good low-frequency excitation effect.

[0026] 2. The excitation platform can be used for loads of different masses. The pressure of the air chamber is controlled by adjusting the pressure valve, so as to match the loads of various masses and ensure sufficient load-bearing capacity. It can be used for excitation systems with large loads.

[0027] 3. The horizontal pendulum structure of the excitation platform can adjust its horizontal stiffness by changing the size of the tie rod, thereby better matching it with the vertical stiffness and reducing the coupling phenomenon when the target load is excited in multiple directions.

[0028] 4. The excitation platform, by configuring six actuator units on the load platform, can independently control the excitation effect of the six degrees of freedom of the excitation system using the modal decoupling method, without needing to change the installation range and direction of the exciter.

[0029] 5. The excitation platform can be combined into different configurations as needed. The number and layout of the exciters can be increased and changed according to the load requirements, making it suitable for excitation needs in more application scenarios. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a six-degree-of-freedom, high-load, low-frequency excitation platform based on an air spring provided by the present invention;

[0031] Figure 2 yes Figure 1 The structural principle diagram of the six-degree-of-freedom high-load low-frequency excitation platform based on air springs;

[0032] Figure 3 yes Figure 1 A schematic diagram showing the distribution of actuators and sensors in a six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs.

[0033] Figure 4 yes Figure 1 A cross-sectional view of a six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs;

[0034] Figure 5 yes Figure 1 A partial structural schematic diagram of a six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs;

[0035] Figure 6 yes Figure 1 A schematic diagram illustrating the effect of excitation transmissibility on a six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs.

[0036] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-base, 2-upper end plate, 3-air spring, 4-1-support plate, 4-2-pull rod, 4-3-connecting column, 4-4-inner pressure plate, 4-5-rubber mold, 4-6-outer pressure plate, 5-1-limiting bolt, 5-2-limiting sleeve, 6-horizontal Lorentz motor, 7-vertical Lorentz motor, 8-pressure valve, 9-air pipe, 10-horizontal eddy current sensor, 11-vertical eddy current sensor. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0038] This invention provides a six-degree-of-freedom high-load low-frequency excitation platform based on an air spring 3. The excitation platform, through the decoupled cooperation of the air spring 3 and the actuator motor output, provides the target system with an effective excitation force of six degrees of freedom and a wide frequency range while ensuring that the platform has sufficient load-bearing capacity (3 tons and above). This ensures that the excitation requirements of the target system for each frequency band, especially the low-frequency band, can be accurately met.

[0039] Please see Figure 1 and Figure 2 This invention provides a six-degree-of-freedom, high-load, low-frequency vibration platform based on an air spring 3. The vibration platform includes a load platform, at least three exciters, and an external foundation. The at least three exciters are evenly arranged around the central axis of the load platform. The opposite ends of the exciters are connected to the load platform and the external foundation, respectively. The load platform is used to connect to the equipment requiring vibration.

[0040] Please see Figure 3 , Figure 4 and Figure 5 The vibrator includes a base 1, an upper end plate 2, a horizontal swing mechanism, a limiting mechanism, a horizontal Lorentz motor 6, a vertical Lorentz motor 7, a pressure valve 8, an air pipe 9, a horizontal eddy current sensor 10, a vertical eddy current displacement sensor, and a controller. The horizontal swing mechanism is disposed within the base 1. The horizontal Lorentz motor 6 and the vertical Lorentz motor 7 are respectively disposed on the outer periphery of the base 1. The pressure valve 8 is connected to the base 1 via the air pipe 9. The horizontal eddy current sensor 10 and the vertical eddy current displacement sensor are respectively connected to the base 1, the vertical Lorentz motor 7, and the horizontal Lorentz motor 6, and the vertical Lorentz motor 7 and the horizontal Lorentz motor 6 are actuator motors. The upper end plate 2 is connected to the base 1 via the limiting mechanism. The controller is connected to the horizontal Lorentz motor 6 and the vertical Lorentz motor 7. The vibrator is connected to the external foundation and the load platform via the base 1 and the upper end plate 2.

[0041] The base 1 is essentially barrel-shaped and has a receiving cavity for accommodating the horizontal swing mechanism. A boss extends from the open end of the base 1 toward its central axis, and the boss forms a first through hole. The central axis of the first through hole coincides with the central axis of the base 1. A supporting cylinder is provided on the boss, which supports the upper end plate 2 during descent.

[0042] In this embodiment, the receiving cavity formed by the base 1 is cylindrical, and its exterior has a hexahedral structure. A horizontal Lorentz motor 6, a vertical Lorentz motor 7, a horizontal eddy current displacement sensor, a vertical eddy current displacement sensor, and a pressure valve 8 are respectively installed around the base 1. The horizontal pendulum mechanism is disposed within the receiving cavity and is connected to the boss and the upper end plate 2.

[0043] The horizontal Lorentz motor 6 and the vertical Lorentz motor 7 are arranged horizontally and vertically around the base 1, respectively. The magnets and movers of the motors are fixed to the lower surface of the upper end plate 2 and the outer circumference of the base 1, respectively. The horizontal Lorentz motor 6 and the vertical Lorentz motor 7 are used to provide excitation forces in various directions of the excitation platform. The controller is used to calculate the output force of each motor of the exciter according to the magnitude and direction requirements of the target load for the excitation force during operation. By decoupling the motor output at the center of mass, individual excitation of the target load in six degrees of freedom can be achieved.

[0044] For each vibrator, since the horizontal and vertical motors are symmetrically arranged and have identical performance, the output of a single vibrator can be equivalent to the horizontal and vertical force applied to the load at the connection point. The controller is used to calculate the magnitude of the motor output in each direction of the vibrator based on the required magnitude and direction of the excitation force during operation.

[0045] For a vibration excitation platform, to achieve individual excitation of the target load in all six degrees of freedom, it is necessary to decouple the motor outputs in each direction at the center of mass. For example... Figure 3 As shown, a global coordinate system ∑ is established based on the load centroid in equilibrium state. O Define the load centroid C in ∑ O The displacement of the six degrees of freedom is r, and the excitation force acting on the center of mass of the load is F. c Therefore, we have:

[0046] r = [xyz α β γ] T (1)

[0047] F c =[F x F y F z M x M y M z ] T (2)

[0048] Define o pi The connection point between the i-th exciter and the support platform is in ∑ O The coordinates in (o) pi )0 represents the point in ∑ OThe initial position in q i Then the point is in ∑ O The displacement in the middle, therefore:

[0049] q i =[x i y i z i ] = o pi -(o pi )0(i=1,2,3) (3)

[0050] Let the output force of the actuator in the entire vibration platform be:

[0051] F = [f h1 f h2 f h3 f v1 f v2 f v3 ] T (4)

[0052] The subscript letter 'h' represents the horizontal direction, 'v' represents the vertical direction, and the subscript number indicates the exciter's serial number. ′ Let C be the centroid of the equilateral triangle, and let C be the mass center. i It is from the center of mass C to f hi The distance can be determined from the force analysis:

[0053]

[0054] Therefore:

[0055]

[0056] Where for ∑h i and p xy They are respectively:

[0057] ∑h i =h1+h2+h3 (7)

[0058] p xy =x1y2-x2y1-x1y3+x3y1+x2y3-x3y2 (8)

[0059] Equation (6) is the output matrix of the vibration platform actuator. Through this matrix, the excitation force that is desired to act on the center of mass of the load can be converted into the individual output force of the actuator in each direction, thereby realizing individual excitation in six degrees of freedom. Furthermore, since the load has been floated by the air spring 3 to overcome the influence of gravity, the motor output can be used entirely for the excitation of the target load, which can significantly enhance the excitation effect.

[0060] The horizontal and vertical eddy current displacement sensors are respectively mounted horizontally on the motor housing and on the base 1. These sensors collect position information of the target load in different directions and feed the displacement signals back to the controller. The eddy current displacement sensors determine whether the motor output is correct by detecting the load displacement, forming a closed-loop control for low-frequency excitation. Furthermore, the vertical eddy current displacement sensor is also used for closed-loop control of the air circuit loop when the load floats.

[0061] Among them, the horizontal eddy current displacement sensor is used to obtain the horizontal displacement s of the upper end plate 2. hi (i = 1, 2, 3) are used to detect whether the applied excitation is correct; the vertical eddy current displacement sensor is used to obtain the vertical displacement s of the upper end plate 2. vi (i = 1, 2, 3) are used to implement closed-loop control when the upper end plate 2 floats. In addition, when the exciter needs to provide low-frequency excitation force below 2Hz, it is necessary to use an eddy current displacement sensor to detect whether the motor output is correct, thus forming a closed-loop control for low-frequency excitation.

[0062] The horizontal swing mechanism includes a support plate 4-1, three tie rods 4-2, a connecting column 4-3, an inner pressure plate 4-4, a rubber mold 4-5, and an outer pressure plate 4-6. The support plate 4-1 is a T-shaped rotating body with a first receiving hole that penetrates the plate body. The upper surface of the plate body is coplanar with the surface of the boss. The rubber mold 4-5 is annular, with its inner and outer edges respectively located on the plate body and the boss. The inner pressure plate 4-4 is located on the plate body and presses against the inner edge of the rubber mold 4-5. The outer pressure plate 4-6 is located on the boss and presses against the outer edge of the rubber mold 4-5.

[0063] The inner pressure plate 4-4 has a second through hole. The connecting post 4-3 is stepped, with one end passing through the second through hole and connected to the upper end plate 2, and the other end located in the receiving hole. One end of the pull rod 4-2 is connected to the inner pressure plate 4-4, and the other end is connected to the step of the connecting post 4-3. In this embodiment, the three pull rods 4-2 are evenly arranged around the second through hole, and the central axis of the second through hole coincides with the central axis of the connecting post 4-3.

[0064] In this embodiment, the tie rod 4-2 is a flexible metal rod with low bending stiffness and high tensile stiffness. This ensures that while providing a large vertical support force for the load, it can also achieve low stiffness in the horizontal direction, thereby improving the excitation effect in the horizontal direction.

[0065] Three tie rods 4-2 are connected in parallel to form a pendulum mechanism, and the connecting column supports the load in the vertical direction by transmitting force with the tie rods 4-2, so that the load and the base 1 are isolated by the tie rods 4-2, which reduces the stiffness of the excitation platform in the horizontal direction.

[0066] The stiffness expression of the horizontal pendulum mechanism can be derived from the rotational equilibrium equation of tie rod 4-2 as follows:

[0067]

[0068] Where E is the Young's modulus of the flexible rod (i.e., tie rod 4-2). Let be the active inertia of the bent section of the flexible rod, l and d be the length and diameter of the bent section, and L be the overall length of the flexible rod. The formula shows that the stiffness of the horizontal pendulum mechanism is related to the material and shape of the flexible rod, as well as the mass of the load. By changing the characteristics of the flexible rod itself, the horizontal resonant frequency of the exciter can be controlled within a frequency range that matches the vertical frequency, thereby improving the consistency of the excitation platform in the six degrees of freedom directions.

[0069] The receiving cavity, the support plate 4-1, the boss, and the rubber mold 4-5 constitute the air spring 3, and the air pipe 9 is connected to the receiving cavity. The pressure valve 8 is used to control the pressure of the gas filling the air chamber of the air spring 3, so as to float loads of different masses to overcome the influence of the load's gravity during excitation. Preferably, the air spring 3 has the characteristics of both low stiffness and high load-bearing capacity, which can float the target load in the vertical direction during excitation, reduce the stiffness of the excitation platform in the vertical direction, and thus more easily achieve the purpose of low-frequency excitation.

[0070] Compressed air is introduced into the air spring 3 through the pressure valve 8 and the air pipe 9. The air spring 3 deforms through the rubber mold 4-5 to apply the pressure of the compressed air to the load, causing the load to float vertically, thereby reducing the vertical stiffness of the target load. For loads of different masses, the pressure of the gas entering the air spring 3 can be controlled by adjusting the size of the pressure valve 8, thereby enabling loads of different masses to be floated to overcome the influence of the load's gravity during vibration.

[0071] Assuming the dynamic process of the gas within the air chamber is an adiabatic process for an ideal gas, the stiffness expression of air spring 3 can be derived from the force relationships and equilibrium equations as follows:

[0072]

[0073] Where κ = 1.4 is the adiabatic coefficient, M is the mass of the load under static equilibrium, g is the acceleration due to gravity, and P... atmLet A be the atmospheric pressure, V0 be the effective cross-sectional area of ​​the air chamber, and V0 be the initial volume of the air chamber under static equilibrium. From formula (10), it can be seen that the stiffness of the air spring 3 is related to the load mass, the effective cross-sectional area of ​​the air chamber, and the initial volume. Analysis and calculation show that when the load mass is controlled within 8 tons, the vertical resonant frequency of the exciter is within the range of 3Hz to 8Hz, at which point the excitation platform has good transmission performance.

[0074] Please see Figure 5 The limiting mechanism includes a limiting bolt 5-1 and a limiting sleeve 5-2. One end of the limiting bolt 5-1 is mounted on the supporting cylinder, and the other end passes through a countersunk hole in the upper end plate 2. The limiting sleeve 5-2 is detachably mounted on the limiting bolt 5-1 and engages with the countersunk hole to limit the upper end plate 2, thereby limiting the load device. The limiting mechanism is used to restrict the vertical and horizontal displacement of the upper end plate 2 during operation. The limiting sleeve 5-2 is a stepped circular rotating component with different diameters and lengths in each axial section. It is used for locking and limiting the upper end plate 2 by forward and reverse installation, respectively. When the limiting sleeve 5-2 is installed in the forward direction, the smaller diameter section faces downward. This diameter is smaller than the inner diameter of the countersunk hole in the upper end plate 2, and the two are coaxially positioned, which can limit the horizontal displacement of the upper end plate 2, with a maximum horizontal displacement of 2mm. At the same time, the axial dimension of this section is relatively long, and the vertical displacement of the upper end plate 2 during the floating process is limited by the stepped surface, with a maximum vertical displacement of 3mm. When the limiting sleeve 5-2 is installed in the reverse direction, the larger diameter section faces downward, and it transitions into the countersunk hole of the upper end plate 2, locking the horizontal displacement. At the same time, the stepped surface of the limiting sleeve 5-2 contacts the upper surface of the countersunk hole, and the vertical displacement is also locked.

[0075] In this embodiment, the number of supporting cylinders is the same as the number of limiting bolts, and one end of the limiting bolt is connected to the supporting cylinder; the supporting cylinder has a threaded mounting hole, and one end of the limiting bolt is threadedly connected to the threaded mounting hole, so that the limiting bolt is connected to the supporting cylinder.

[0076] The vibration platform structure used in this embodiment is composed of mass, damping, and springs to achieve the transmission of vibration force. The transfer function curve from the vibration force to the target load velocity response is as follows:

[0077]

[0078]

[0079] Where V(s) is the Laplace transform of the target load velocity response, X(s) is the Laplace transform of the target load displacement response, F(s) is the operating characteristic curve of a single Lorentz motor in the frequency domain, F0 is the target output value of the motor, m is the mass of the target load acting on a single exciter, c and k are the equivalent damping and equivalent stiffness of the mechanism used, s = j2πf is the complex variable of the Laplace transform, and f is the frequency.

[0080] From equations (11) and (12), it can be seen that for a single exciter, four Lorentz motors are set in the horizontal and vertical directions respectively, with a maximum output of 440N. Therefore, under the action of the rated peak force of the motor, the maximum speed response of the target load in the frequency domain is:

[0081]

[0082] Specifically, when the resonant frequency of the exciter is 4.5Hz, the velocity response curve of the target load in the frequency domain is as follows: Figure 6 As shown. Preferably, the international VC (Vibration Criterion) curve is used to measure the excitation effect on the target load in this example. The amplitude of VC-A level vibration is 50 μm / s (34 dB), and the amplitude of Residential Day (ISO) level vibration is 200 μm / s (46 dB). (Refer to...) Figure 6 It can be seen that when the Residential Day (ISO) vibration level is defined as the effective excitation standard of the exciter for the target load, the effective excitation bandwidth of this embodiment is approximately 0.1Hz to 200Hz. Analysis of the target load's velocity response in the frequency domain when the excitation platform operates in the resonant frequency range of 3Hz to 8Hz shows that this embodiment has a significant excitation effect on large load objects in the low-frequency range and exhibits excellent linearity, making it suitable for excitation requirements in most situations.

[0083] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs, characterized in that: The vibration platform includes a vibrator, which includes an upper end plate, a base, and a horizontal swing mechanism. The horizontal swing mechanism is partially disposed within the base, and the upper end plate is connected to the base. The base and the horizontal swing mechanism together form an air spring, which is disposed opposite to the upper end plate. The upper end plate is used to connect a load. The vibration platform causes the air spring to deform by introducing air into it, thereby lifting the upper end plate and the load. The vibration platform includes a controller, a horizontal Lorentz motor, and a vertical Lorentz motor. The controller is connected to the horizontal and vertical Lorentz motors respectively. The horizontal and vertical Lorentz motors are respectively arranged on the outer periphery of the base in the horizontal and vertical directions. The magnets and movers of the motors are respectively fixed to the lower surface of the upper end plate and the outer periphery of the base. The horizontal and vertical Lorentz motors are used to provide vibration force in various directions of the vibration platform. The controller is used to calculate the output force of each motor of the vibrator according to the load's requirements for the magnitude and direction of the excitation force during operation, and to achieve individual excitation of the load in six degrees of freedom by decoupling the motor output at the center of mass; the output matrix of the motors of the excitation platform is as follows: In the formula, the subscript letter h represents the horizontal direction, v represents the vertical direction, and the subscript number represents the exciter number; ; Establish a global coordinate system based on the load centroid under equilibrium conditions. Define the load centroid C in The displacement of the six degrees of freedom is r The excitation force acting on the center of mass of the load is Therefore, we have: definition For the first i The connection point between the exciter and the support platform is at coordinates in For this point at The initial position in Then the point is at The displacement in the middle, therefore: 。 2. The six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs as described in claim 1, characterized in that: The vibration platform also includes an air pipe and a pressure valve. The pressure valve is connected to the air spring through the air pipe, and the pressure inside the air spring is controlled by the pressure valve to match loads of different masses.

3. The six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs as described in claim 1, characterized in that: The controller converts the excitation force intended to act on the load's center of mass into individual output forces of the motors in each direction through the output matrix, thereby achieving individual excitation in six degrees of freedom.

4. The six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs as described in claim 1, characterized in that: The vibration platform also includes horizontal eddy current displacement sensors and vertical eddy current displacement sensors. Multiple horizontal and vertical eddy current displacement sensors are respectively arranged on the motor housing and base in the horizontal and vertical directions. The horizontal and vertical eddy current displacement sensors are used to collect the position information of the load in different directions and feed the displacement signal back to the controller. The controller is used to control the motors accordingly based on the received displacement signals to keep the output of each motor at the required value.

5. The six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs as described in any one of claims 1-4, characterized in that: The base is basically barrel-shaped and has a receiving cavity for accommodating the horizontal swing mechanism; the open end of the base extends toward its own central axis with a boss, and the boss has a first through hole; the horizontal swing mechanism is disposed in the receiving cavity and is connected to the boss and the upper end plate.

6. The six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs as described in claim 5, characterized in that: The horizontal swing mechanism includes a support plate, an inner pressure plate, a rubber mold, and an outer pressure plate. The support plate is a T-shaped rotating body with a first receiving hole that penetrates the plate body. The upper surface of the plate body is coplanar with the surface of the boss. The rubber mold is annular, with its inner and outer edges respectively disposed on the plate body and the boss. The inner pressure plate is disposed on the plate body and presses against the inner edge of the rubber mold. The outer pressure plate is disposed on the boss and presses against the outer edge of the rubber mold.

7. The six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs as described in claim 6, characterized in that: The horizontal swing mechanism also includes three tie rods and a connecting column. The inner pressure plate has a second through hole. The connecting column is stepped, with one end passing through the second through hole and connected to the upper end plate, and the other end located in the receiving hole. One end of the tie rod is connected to the inner pressure plate, and the other end is connected to the step of the connecting column.

8. The six-degree-of-freedom, high-load, low-frequency excitation platform based on air springs as described in claim 7, characterized in that: The number of the pull rods is three, and the three pull rods are evenly arranged around the second through hole; the pull rods are flexible metal rods, and the three pull rods are connected in parallel to form a pendulum mechanism.

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