Self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table

Abstract

A self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation platform, comprising a base platform, a working platform and a plurality of leg mechanisms with quasi-zero stiffness characteristics arranged therebetween, wherein: the two ends of the leg mechanism are connected through a universal joint between the base platform and the working platform to realize spatial six-degree-of-freedom wide-band vibration isolation. The present application uses a nonlinear gradually hard positive stiffness structure to modulate a negative stiffness structure to design a passive quasi-zero stiffness structure and an active quasi-zero stiffness structure. The rated load of the active quasi-zero stiffness vibration isolation structure is proportional to the current size. The passive quasi-zero stiffness structure and the active quasi-zero stiffness structure are combined. By adjusting the rated load of the active quasi-zero stiffness structure, the self-leveling function of the vibration isolation platform under different loads is realized. The passive quasi-zero stiffness structure is beneficial to provide the carrying capacity and reliability of the vibration isolation platform. Compared with the existing six-degree-of-freedom quasi-zero stiffness vibration isolation platform, the present application has a large carrying capacity, high reliability, is not sensitive to the vibration isolation load, and can realize the self-leveling of the working platform under different loads, which not only ensures the excellent low-frequency vibration isolation performance of itself, but also ensures that the vibration isolation object can work normally.

Description

Technical Field

[0001] This invention relates to a technology in the field of vibration isolation, specifically a self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table. Background Technology

[0002] Quasi-zero stiffness vibration isolation is a nonlinear vibration isolation method that uses stiffness nonlinearity to give the isolation system both high static stiffness and low dynamic stiffness. Compared to traditional linear vibration isolation methods, it has the advantages of low natural frequency and wide isolation bandwidth, effectively suppressing low-frequency vibrations. However, the nonlinearity of stiffness creates coupling relationships not only between force and displacement, but also between stiffness and displacement, making the quasi-zero stiffness isolation system more sensitive to loads. When the applied load is mismatched with the rated load of the isolation system, the system's operating position will deviate from the quasi-zero stiffness range, and the vibration isolation performance will deteriorate. In parallel multi-degree-of-freedom quasi-zero stiffness vibration isolation platforms, load asymmetry, installation eccentricity, and mismatch can cause different lengths of the parallel legs. On the one hand, this will cause the parallel legs to deviate from the quasi-zero stiffness range, deteriorating the vibration isolation performance; on the other hand, it will cause the working platform to tilt, preventing the isolated precision instruments and equipment from operating normally. The existing six-degree-of-freedom quasi-zero stiffness vibration isolation platform legs achieve quasi-zero stiffness characteristics by connecting a bistable negative stiffness structure in parallel with a linear spring. However, it does not consider the above-mentioned problems or adjust the rated load by manually adjusting the compression of the linear spring to ensure the vibration isolation performance of the platform under different loads. This makes operation inconvenient and limits its practical application. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention proposes a self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table. It utilizes a nonlinear gradually hardening positive stiffness structure to modulate a negative stiffness structure, designing both a passive and an active quasi-zero stiffness structure. The rated load of the active quasi-zero stiffness isolation structure is proportional to the current. By combining the passive and active quasi-zero stiffness structures, the self-leveling function of the isolation table under different loads is achieved by adjusting the rated load of the active quasi-zero stiffness structure. Meanwhile, the passive quasi-zero stiffness structure contributes to improving the load-bearing capacity and reliability of the isolation table. Compared to existing six-degree-of-freedom quasi-zero stiffness vibration isolation platforms, this invention offers higher load-bearing capacity, stronger reliability, insensitivity to vibration isolation loads, and the ability to achieve self-leveling under different loads, ensuring both excellent low-frequency vibration isolation performance and the normal operation of the isolated object.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table, comprising: a base platform, a working platform, and several support leg mechanisms with quasi-zero stiffness characteristics disposed between the two, wherein: the two ends of the support leg mechanisms are connected to the base platform and the working platform respectively through universal joints to achieve spatial six-degree-of-freedom broadband vibration isolation.

[0006] The outrigger mechanism is preferably six in number, with twelve universal joints forming a Gough-Stewart configuration with the base platform and the working platform respectively.

[0007] Technical effect

[0008] This invention employs a gradually stiffening positive stiffness structure modulating a negative stiffness structure to design an active quasi-zero stiffness structure, whose rated load is proportional to the current magnitude. The active quasi-zero stiffness structure and the passive quasi-zero stiffness structure are combined to form the legs of a multi-degree-of-freedom vibration isolation table. Compared to existing technologies, this invention has no requirements for the load installation of the vibration isolation table; the load installation of the vibration isolation table can be eccentric; there are no requirements for the load size, and the vibration isolation table can operate under a wide range of loads; the posture of the vibration isolation table's working platform can be adjusted to avoid the working platform tilting and affecting the normal operation of the object being isolated. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the overall structure of the quasi-zero stiffness vibration isolation table of the present invention;

[0010] Figure 2 A schematic diagram of the overall structure of the vibration isolation table support legs;

[0011] Figure 3 This is a sectional view of the support leg of the vibration isolation table;

[0012] Figure 4 A schematic diagram of the assembly of a negative stiffness coil for an active quasi-zero stiffness structure;

[0013] Figure 5 Force-displacement curves of the positive stiffness structure and negative stiffness structure of the outrigger of this invention;

[0014] Figure 6 This is a stiffness-displacement relationship diagram of the passive quasi-zero stiffness structure of the present invention;

[0015] Figure 7 This is a force-displacement relationship diagram of the active quasi-zero stiffness structure of the present invention under different currents;

[0016] In the diagram: 1. Base platform; 2. Support leg; 3. Working platform; 4. First universal joint; 5. Second universal joint; 201. Base; 202. Support column; 203. Cantilever beam; 204. Rolling bearing housing; 205. Hemisphere; 206. Coil mounting base; 207. Linear bearing housing; 208. Bearing end cover; 209. Connecting flange; 210. First bolt; 211. Second bolt; 212. First rolling bearing; 213. Third bolt; 214. Clamping block; 215. Fourth bolt; 21 6. Fifth bolt, 217. First linear bearing, 218. First permanent magnet, 219. Pin, 220. First coil, 221. Second permanent magnet, 222. Second linear bearing, 223. Second rolling bearing, 224. Locking nut, 225. Sixth bolt, 226. Guide rod, 227. First nut, 228. Sleeve, 229. Second nut, 230. Third nut, 231. Elastic retaining ring, 232. Third permanent magnet, 233. Second coil, 234. Seventh bolt. Detailed Implementation

[0017] like Figure 1 As shown, this embodiment relates to a self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table, including: a base platform 1, a working platform 3, and several support leg mechanisms 2 with quasi-zero stiffness characteristics disposed between the two. The two ends of the support leg mechanisms 2 are connected to the base platform 1 and the working platform 3 respectively through universal joints 4 and 5 to achieve spatial six-degree-of-freedom broadband vibration isolation.

[0018] The outrigger mechanism 2 is preferably six in number, with twelve universal joints 4 and 5 forming a Gough-Stewart configuration with the base platform 1 and the working platform 3 respectively.

[0019] like Figure 2 and Figure 3 As shown, the outrigger mechanism 2 includes: a base 201, several support columns 202, a linear motion component, a rotary motion component, a passive quasi-zero stiffness structure, and an active quasi-zero stiffness structure. Among them, several support columns 202 are fixedly arranged between the base 201 and the active quasi-zero stiffness structure. The linear motion component is disposed through the base 201 and the active quasi-zero stiffness structure. The rotary motion component and the passive quasi-zero stiffness structure are respectively disposed on the linear motion component, and the passive quasi-zero stiffness structure is located inside the support columns 202.

[0020] The base 201 is provided with circumferentially distributed grooves that match the cross-sectional shape of the support column 202, for interference fit with the support column 202.

[0021] The linear motion assembly includes: a guide rod 226, a first linear bearing 217, a second linear bearing 222, and a linear bearing housing 207, wherein: the first linear bearing 217 and the second linear bearing 222 are respectively sleeved on both ends of the guide rod 226 and restrict the guide rod 226 to only perform linear motion, and the linear bearing housing 207 is disposed outside the second linear bearing 222.

[0022] The base 201 is provided with a central hole for mounting a first linear bearing 217, which is fixed to the base 201 by a fifth bolt 216.

[0023] The rotary motion assembly includes: a second rolling bearing 223, a connecting flange 209, a bearing end cover 208, and a locking nut 224, wherein: the outer ring of the second rolling bearing 223 is embedded in the connecting flange 209, and the inner ring of the second rolling bearing 223 is interference-fitted onto the guide rod 226 of the linear motion assembly, and the guide rod 226 is rotatable relative to the connecting flange 209.

[0024] The passive quasi-zero stiffness structure includes: a first permanent magnet 218, a third permanent magnet 232, a hemisphere 205, several cantilever beams 203, a clamping block 214, a first rolling bearing 212, and a rolling bearing seat 204. The hemisphere 205, the first permanent magnet 218, and the third permanent magnet 232 are sequentially arranged on the linear motion assembly. One end of each cantilever beam 203 is fixed to the base 201 by the clamping block 214, and the other end is in contact with the outer wall of the hemisphere 205 through the first rolling bearing 212 and the rolling bearing seat 204.

[0025] When under load, the cantilever beam 203 deforms, generating a restoring force. The end of the cantilever beam 203 slides on the surface of the hemisphere 205, altering the force resisting the load and exhibiting non-bistable negative stiffness characteristics. The repulsive force between the first permanent magnet 218 and the third permanent magnet 232 exhibits nonlinear gradually hardening positive stiffness. By adjusting the third nut 230 to change the position of the hemisphere 205, the length of the cantilever beam 203 or the gap between the first permanent magnet 218 and the third permanent magnet 232 can be varied, thus adjusting both positive and negative stiffness.

[0026] The first permanent magnet 218 is fixedly mounted on the guide rod 226 of the linear motion assembly, with one side pressed against the shaft shoulder and the other side pressed by the elastic retaining ring 231.

[0027] The third permanent magnet 232 is embedded in the circular groove of the base 201.

[0028] The hemisphere 205 is mounted on the guide rod 226 through a central threaded hole. A third nut 230 is provided on the guide rod. Adjusting the third nut 230 can adjust the position of the hemisphere 205 on the guide rod 226.

[0029] The cantilever beams 203 are preferably four in number and are evenly distributed vertically around the circumference.

[0030] The first rolling bearing 212 is fixed to the rolling bearing seat 204 by a pin 219, and the rolling bearing seat 204 is fixedly connected to the other end of the cantilever beam 203 by a third bolt 213.

[0031] The active quasi-zero stiffness structure includes: a second coil 233, a second permanent magnet 221, a first coil 220, and a coil mounting base 206, wherein: the second coil 233 is disposed at one end of the support column 202 inside the base 201, the first coil 220 is disposed opposite to the other end of the support column 202 through the coil mounting base 206, and the second permanent magnet 221 is disposed on the linear motion component through the sleeve 229 and is located between the first coil 220 and the second coil 233.

[0032] The sleeve 228 has a central threaded hole and is screwed onto the guide rod 226. The position of the second permanent magnet 221 is limited by the second nut 229 screwed onto the guide rod 226. Adjusting the second nut 230 can change the position of the second permanent magnet 221.

[0033] The second coil 233 is directly opposite the first permanent magnet 218 and has a repulsive effect between them, providing nonlinear gradually hardening positive stiffness; the first coil 220 and the second permanent magnet 221 are nested together and have a repulsive effect between them, providing negative stiffness; according to Ampere's law, the negative stiffness and positive stiffness are proportional to the magnitude of the current.

[0034] Apart from the permanent magnet, the other components of the vibration isolation table are preferably made of weakly magnetic materials.

[0035] like Figure 5 , Figure 6 As shown, the outrigger 2 connects a nonlinear gradually stiffening positive stiffness structure and a non-bistable negative stiffness structure in parallel, achieving quasi-zero stiffness characteristics.

[0036] like Figure 7 As shown, the first coil 220 and the second coil 233 are connected in series. According to Ampere's law, the rated load of the support leg 2 can be changed by adjusting the current.

[0037] Except for permanent magnets 10 and 15, the components of the vibration isolation device are preferably made of low magnetic permeability materials.

[0038] Compared to traditional six-degree-of-freedom quasi-zero stiffness vibration isolation tables that combine a bistable negative stiffness structure with a linear spring in parallel, this device utilizes a nonlinear gradually hardening positive stiffness structure to modulate the negative stiffness structure, achieving an active quasi-zero stiffness structure where the rated load is proportional to the current. The active and passive quasi-zero stiffness structures are combined to form the legs of the multi-degree-of-freedom vibration isolation table, making the table unrestricted by load installation requirements and allowing for eccentric installation. It is also unrestricted by load size, enabling operation under a wide range of loads. Combined with sensors and a microcontroller, the working platform can self-level under different loading conditions, preventing platform tilt from affecting the normal operation of the isolated object.

[0039] Compared with existing technologies, this invention utilizes a nonlinear positive stiffness structure to modulate a negative stiffness structure, designing both passive and active quasi-zero stiffness structures. The passive quasi-zero stiffness structure can withstand large loads without requiring energy input, thus improving the load-bearing capacity and reliability of the vibration isolation platform. The rated load of the active quasi-zero stiffness structure is proportional to the magnitude of the energized current, and the rated load of the support leg 2 can be adjusted by regulating the current. Combined with sensors and a microprocessor, the vibration isolation platform can achieve self-leveling operation under different loading conditions. This ensures both the wideband vibration isolation performance of the platform for different vibration-isolated objects and prevents the vibration-isolated objects from being affected by their own tilt, thus maintaining normal operation.

[0040] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table, characterized in that, include: The base platform, the working platform, and several outrigger mechanisms with quasi-zero stiffness characteristics are arranged between the two. The two ends of the outrigger mechanisms are connected to the base platform and the working platform respectively through universal joints to achieve spatial six-degree-of-freedom broadband vibration isolation. The outrigger mechanism includes: a base, several support columns, a linear motion component, a rotary motion component, a passive quasi-zero stiffness structure, and an active quasi-zero stiffness structure, wherein: several support columns are fixedly arranged between the base and the active quasi-zero stiffness structure; the linear motion component is disposed through the base and the active quasi-zero stiffness structure; the rotary motion component and the passive quasi-zero stiffness structure are respectively disposed on the linear motion component, and the passive quasi-zero stiffness structure is located inside the support columns; The passive quasi-zero stiffness structure includes: a first permanent magnet, a third permanent magnet, a hemisphere, several cantilever beams, a clamping block, a first rolling bearing, and a rolling bearing seat, wherein: the hemisphere, the first permanent magnet, and the third permanent magnet are sequentially arranged on the linear motion assembly; one end of the several cantilever beams is fixed to the base by the clamping block, and the other end is in contact with the outer wall of the hemisphere through the first rolling bearing and the rolling bearing seat; When under load, the cantilever beam deforms and generates restoring force. The end of the cantilever beam slides on the surface of the hemisphere, changing the force resisting the load and exhibiting non-bistable negative stiffness characteristics. The repulsive force between the first and third permanent magnets has nonlinear gradually hardening positive stiffness. By adjusting the third nut to change the position of the hemisphere, the length of the cantilever beam or the gap between the first and third permanent magnets can be varied, thereby adjusting the positive and negative stiffness. The active quasi-zero stiffness structure includes: a second coil, a second permanent magnet, a first coil, and a coil mounting base, wherein: the second coil is disposed at one end of the support column inside the base, the first coil is disposed opposite to the other end of the support column through the coil mounting base, and the second permanent magnet is disposed on the linear motion component through a sleeve and is located between the first coil and the second coil; The second coil is directly opposite the first permanent magnet, and there is a repulsive effect between them, providing nonlinear gradually hardening positive stiffness; the first coil and the second permanent magnet are nested together, and there is a repulsive effect between them, providing negative stiffness; according to Ampere's law, the negative stiffness and positive stiffness are proportional to the magnitude of the current.

2. The self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table according to claim 1, characterized in that, The linear motion assembly includes: a guide rod, a first linear bearing, a second linear bearing, and a linear bearing housing, wherein: the first linear bearing and the second linear bearing are respectively sleeved on both ends of the guide rod and restrict the guide rod to only perform linear motion, and the linear bearing housing is disposed outside the second linear bearing.

3. The self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table according to claim 1, characterized in that, The outrigger mechanism consists of six legs, corresponding to twelve universal joints that together with the base platform and the working platform form a Gough-Stewart configuration.

4. The self-leveling six-degree-of-freedom quasi-zero stiffness vibration isolation table according to claim 1, characterized in that, The rotary motion assembly includes: a second rolling bearing, a connecting flange, a bearing end cap, and a locking nut, wherein: the outer ring of the second rolling bearing is embedded in the connecting flange, and the inner ring of the second rolling bearing is interference-fitted onto the guide rod of the linear motion assembly, and the guide rod is rotatable relative to the connecting flange.

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