Cable Multimodal Control Device and Method Based on Passive Adjustable Stiffness-Damper

Abstract

This invention relates to the field of vibration control technology, and more particularly to a cable multimodal control device and method based on a passive adjustable stiffness-damper. The device includes a mechanical damper and an adjustable equivalent stiffness device. The adjustable equivalent stiffness device comprises a preloaded spring-type negative stiffness mechanism, a lever-type positive stiffness mechanism, and a power mechanism. The lever-type positive stiffness mechanism changes the equivalent stiffness generated by the series connection of the preloaded spring-type negative stiffness mechanism and the lever-type positive stiffness mechanism by changing the lever ratio. The power mechanism is installed between the cable and the ground to sense the cable's vibration, generate relative motion with it, and drive the lever-type positive stiffness mechanism, thereby changing the lever ratio of the lever-type positive stiffness mechanism. Through a purely mechanical structure, this invention provides a novel solution for multimodal control of cables targeting nodal modes, with a wide range of applications. Compared to existing active / semi-active methods that change the dynamic parameters of the damper, it eliminates the need for external power supply.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology, and in particular to a cable multimodal control device and method based on a passively adjustable stiffness-damper. Background Technology

[0002] Due to their light weight, high flexibility, and low inherent damping, cables are prone to various modal vibrations under external environmental conditions or excitation at the anchorage. Installing a single viscous damper is one of the most common and mature methods for controlling cable vibration. However, due to practical installation limitations in engineering projects, viscous dampers or other dampers are often installed near the anchorage. When the installation location coincides with the mode shape node of a higher-order vibration mode, the damper loses its control effect on that mode; this mode is called a "nodal mode." Multimodal vibration control of cables targeting nodal modes has become a major issue in cable vibration control.

[0003] To control nodal modes, there are two main existing solutions: one is to install the damper closer to the anchorage end of the cable; the other is to install additional dampers at other locations to compensate for nodal mode damping. The former allows the damper to be installed away from the nodal points of the possible vibration modes, but this weakens the damper's control effect on the main vibration modes. The latter controls most of the cable's vibration modes through the main damper and controls the nodal modes through the additional dampers. The additional dampers can be installed near the cable end close to the main damper or near another cable end far from the main damper. When installed near another cable end, the damping effects of the two dampers can be approximately superimposed, but this is difficult to achieve in some engineering applications. When installed near the same end, the additional damper can compensate for the mode damping ratio near the nodal, but the overall modal damping gain is limited compared to the case of installing a single damper.

[0004] Therefore, it is necessary to provide a new cable multimodal control device based on a passively adjustable stiffness-damper to solve the above-mentioned technical problems. Summary of the Invention

[0005] The main objective of this invention is to provide a cable multimodal control device and method based on a passively adjustable stiffness-damper, which aims to solve the above-mentioned problems.

[0006] To achieve the above objectives, the first aspect of the present invention provides a cable multimodal control device based on a passive adjustable stiffness-damper, comprising: a mechanical damper and an adjustable equivalent stiffness device;

[0007] The mechanical damper is installed between the cable and the ground;

[0008] The adjustable equivalent stiffness device includes a preloaded spring negative stiffness mechanism, a lever positive stiffness mechanism, and a power mechanism; the preloaded spring negative stiffness mechanism is installed on the cable and is used to change the local stiffness of the cable, thereby changing the control effect of the mechanical damper.

[0009] The lever-type positive stiffness mechanism is installed on the ground and is connected to the pre-compressed spring-type negative stiffness mechanism for transmission; it is used to amplify the equivalent stiffness of the pre-compressed spring-type negative stiffness mechanism; the lever-type positive stiffness mechanism changes the equivalent stiffness generated by the pre-compressed spring-type negative stiffness mechanism and the lever-type positive stiffness mechanism in series by changing the lever ratio.

[0010] The power mechanism is installed between the cable and the ground and is connected to the lever-type positive stiffness mechanism for transmission; it is used to sense the vibration of the cable, generate relative motion with it, and drive the lever-type positive stiffness mechanism, thereby changing the lever ratio of the lever-type positive stiffness mechanism.

[0011] Optionally, the preloaded spring type negative stiffness mechanism includes a first outer frame, a guide sleeve, a guide rod, a pair of first spring assemblies, a first connector, and a second connector;

[0012] The first outer frame is fixedly connected to the guide sleeve;

[0013] The first end of the guide rod is fixedly connected to the cable, and the second end is slidably connected inside the guide sleeve;

[0014] The first connector is fixedly connected to the guide rod;

[0015] A pair of first spring assemblies are symmetrically arranged along the guide rod; one end of the first spring assembly is hinged to the first outer frame, and the other end is hinged to the first connector; when the first spring assembly is in a horizontal position, it is in a pre-compressed state;

[0016] The second connector is fixedly connected to the guide sleeve; the second connector is hinged to the lever-type positive stiffness mechanism.

[0017] Optionally, the lever-type positive stiffness mechanism includes a second spring assembly, a lever, a first slider, and a support;

[0018] The support is installed on the ground;

[0019] The second spring assembly is fixedly connected to the support;

[0020] One end of the lever is hinged to the second connector, and the other end is hinged to the second spring assembly;

[0021] The first slider is slidably connected to the lever, and the first slider is driven by the power mechanism. The first slider serves as the fulcrum of the lever, and when the power mechanism drives the first slider to move, it will change the lever ratio of the lever.

[0022] Optionally, the power mechanism includes a mechanical sensing mechanism, a mechanical drive mechanism, and a mechanical transmission mechanism;

[0023] The first end of the mechanical sensing mechanism is mounted on the cable, and the second end is connected to the mechanical drive mechanism; the mechanical drive mechanism is mounted on the cable; the mechanical transmission mechanism is mounted on the ground and is connected to the lever-type positive stiffness mechanism and the mechanical drive mechanism respectively.

[0024] The mechanical sensing mechanism is used to sense the vibration of the cable, generate relative motion with it, and drive the mechanical drive mechanism, which in turn drives the lever-type positive stiffness mechanism through the mechanical transmission mechanism, thereby changing the lever ratio of the lever-type positive stiffness mechanism.

[0025] Optionally, the mechanical sensing mechanism includes a first mass block, a second mass block, a third spring, a fourth spring, a first damping assembly, a second damping assembly, a first connecting rod, a second connecting rod, and a slide rail;

[0026] One end of the first connecting rod is fixedly connected to the cable, and the other end is fixedly connected to the first mass block;

[0027] The slide is fixedly connected to the cable, and the slide is perpendicular to the cable. The first mass block and the second mass block are slidably connected to the slide.

[0028] One end of the second connecting rod is fixedly connected to the first mass block, and the other end is fixedly connected to the second mass block;

[0029] The first damping component is mounted on the first connecting rod; the third spring is sleeved on the first damping component and connected in parallel with the first damping component;

[0030] The second damping assembly is mounted on the second connecting rod; the fourth spring is sleeved on the second damping assembly and connected in parallel with the second damping assembly;

[0031] The first mass block is connected to the mechanical drive mechanism for driving the mechanical drive mechanism.

[0032] Optionally, the mechanical drive mechanism includes a support arm, a drive shaft, a ratchet, a pawl, and a V-arm;

[0033] The support arm is fixedly connected to the cable;

[0034] The drive shaft is rotatably connected to the support arm and the V-arm respectively, and is fixedly connected to the ratchet;

[0035] The pawl is fixedly connected to the V-arm and engages with the ratchet.

[0036] The V-arm is correspondingly arranged with the first mass block, and the first mass block is used to drive the V-arm to rotate along the transmission shaft;

[0037] The drive shaft is connected to the mechanical transmission mechanism.

[0038] Optionally, the mechanical transmission mechanism includes a second outer frame, a third connecting member, a flexible shaft, a reciprocating lead screw, a second slider, a third slider, and a slide rail;

[0039] The second outer frame is installed on the ground;

[0040] The slide rail is fixedly connected to the second outer frame;

[0041] The reciprocating lead screw is rotatably connected to the second outer frame;

[0042] The second slider and the third slider are respectively fixedly connected to the third connecting member; and the second slider is threadedly connected to the reciprocating lead screw, while the third slider is slidably connected to the slide rail;

[0043] One end of the flexible shaft is fixedly connected to the transmission shaft, and the other end is fixedly connected to the reciprocating lead screw;

[0044] The third connector is rotatably connected to the first slider.

[0045] The second aspect of this invention provides a cable multimodal control method based on a passively adjustable stiffness-damper, employing the aforementioned cable multimodal control device based on a passively adjustable stiffness-damper, comprising the following steps:

[0046] S1: Determine the installation position and damping coefficient of the mechanical damper based on the damping requirements of the large-amplitude low-order modal vibration of the cable and the space requirements of the actual application scenario;

[0047] S2: Determine the installation position and initial equivalent stiffness value of the adjustable equivalent stiffness device based on the installation position and damping coefficient of the mechanical damper, and obtain the nodal mode i of the cable in the initial state, where: i=1,2,...,N; N is the total number of modes; take nodal mode i and the weakly damped modes near it as the target modes for adaptive adjustment;

[0048] S3: Based on the minimum damping ratio requirement that the target mode should meet in engineering practice, determine the stiffness provided by the adjustable equivalent stiffness component required by the target mode to achieve the required minimum damping ratio, thereby determining the adjustable equivalent stiffness range required by the adjustable equivalent stiffness component.

[0049] S4: Design the structure and parameters of the mechanical sensing mechanism in the adjustable equivalent stiffness component according to the frequency range of the control target modal coverage; design the adaptively adjustable trigger threshold according to the engineering vibration control requirements;

[0050] S5: The stay cable vibrates under external load excitation;

[0051] S6: Perform the judgment, specifically:

[0052] If the dynamic characteristics of the mechanical sensing mechanism are lower than the trigger threshold, the target mode does not vibrate significantly and the mechanical drive mechanism is not triggered to operate, that is, the stiffness of the equivalent stiffness component is not triggered to change, and the process returns to S5.

[0053] If the target mode vibrates and the dynamic characteristics of the mechanical sensing mechanism reach the trigger threshold, the mechanical sensing mechanism drives the mechanical drive mechanism to operate, and then the mechanical transmission mechanism converts this motion into a change in equivalent stiffness. The damping ratio of the target mode increases until the dynamic characteristics of the mechanical sensing component fall below the trigger threshold. At this point, the passive self-adjustment process of the equivalent stiffness stops, and the target mode has been effectively controlled. Due to the change in equivalent stiffness, the node mode shifts from node mode i to node mode j, where j = 1, 2, ..., N, and j ≠ i. Node mode j and its nearby weakly damped modes become the new target modes, and the process returns to S5.

[0054] Optionally, the mechanical damper is installed on the mode node of the nodal mode under the influence of the initial stiffness value of the adjustable equivalent stiffness device, and the adjustable equivalent stiffness device is installed near the mechanical damper.

[0055] The technical solution of this invention has the following advantages:

[0056] 1. A novel solution for multimodal control of cables based on nodal modes is provided through a purely mechanical structure. It has a wide range of applications and, compared with existing active / semi-active methods that change the dynamic parameters of the damper, it has the advantage of not requiring external power supply.

[0057] 2. The design of using a preloaded spring negative stiffness mechanism and a lever positive stiffness mechanism in series achieves the control target by amplifying the equivalent negative stiffness value, effectively reducing the engineering and physical implementation difficulty of the preloaded spring negative stiffness mechanism.

[0058] 3. By changing the local stiffness of the cable to amplify the vibration response at the damper, the position of the damper and the mode node are effectively misaligned. Compared with other schemes that directly change the installation position of the vibration absorber through adaptive adjustment, there is no need to change the installation position and connection status of the damper, thus ensuring connection reliability. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0060] Figure 1 This is a front view of the cable multimodal control device based on a passively adjustable stiffness-damper in an embodiment of the present invention.

[0061] Figure 2 This is a perspective view of a cable multimodal control device based on a passively adjustable stiffness-damper in an embodiment of the present invention.

[0062] Figure 3 This is a perspective view of the preloaded spring type negative stiffness mechanism in an embodiment of the present invention;

[0063] Figure 4 This is a perspective view of the lever-type positive stiffness mechanism in an embodiment of the present invention;

[0064] Figure 5 This is a perspective view of the mechanical sensing mechanism in an embodiment of the present invention;

[0065] Figure 6 This is a perspective view of the mechanical drive mechanism in an embodiment of the present invention;

[0066] Figure 7 This is a perspective view of the mechanical transmission mechanism in an embodiment of the present invention;

[0067] Figure 8 This is a simplified mechanical diagram of a cable multimodal control device based on a passively adjustable stiffness-damper in an embodiment of the present invention.

[0068] Figure 9 This is a simplified mechanical diagram of the mechanical sensing mechanism in an embodiment of the present invention;

[0069] Figure 10 This is a simplified mechanical diagram of the preloaded spring negative stiffness mechanism and the lever positive stiffness mechanism connected in series in an embodiment of the present invention;

[0070] Figure 11 This is a schematic diagram illustrating the working principle of the preloaded spring negative stiffness mechanism in an embodiment of the present invention;

[0071] Reference numerals: 1. Mechanical damper; 2. Preloaded spring type negative stiffness mechanism; 201. First outer frame; 202. Guide sleeve; 203. Guide rod; 204. First spring assembly; 205. First connector; 206. Second connector; 3. Lever type positive stiffness mechanism; 301. Second spring assembly; 302. Lever; 303. First slider; 304. Support; 4. Mechanical sensing mechanism; 401. First mass block; 402. Second mass block; 403. Third spring; 404. Fourth spring; 4 05. First damping assembly; 406. Second damping assembly; 407. First connecting rod; 408. Second connecting rod; 409. Slide rail; 5. Mechanical drive mechanism; 501. Support arm; 502. Drive shaft; 503. Ratchet; 504. Pawl; 505. V-arm; 6. Mechanical transmission mechanism; 601. Second outer frame; 602. Third connecting piece; 603. Flexible shaft; 604. Reciprocating screw; 605. Second slider; 606. Third slider; 607. Slide rail; 7. Cable; 8. Ground.

[0072] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0073] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0074] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0075] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0076] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0077] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0078] Example 1

[0079] This invention proposes a cable multimodal control device based on a passive adjustable stiffness-damper, comprising: a mechanical damper 1 and an adjustable equivalent stiffness device;

[0080] The mechanical damper 1 is installed between the cable 7 and the ground 8; the cable 7 is inclined to the ground.

[0081] The adjustable equivalent stiffness device includes a preloaded spring negative stiffness mechanism 2, a lever positive stiffness mechanism 3, and a power mechanism; the preloaded spring negative stiffness mechanism 2 is installed on the cable 7 and is used to change the local stiffness of the cable 7, thereby changing the control effect of the mechanical damper 1.

[0082] The lever-type positive stiffness mechanism 3 is installed on the ground and is connected to the pre-compressed spring-type negative stiffness mechanism 2 for transmission; it is used to amplify the equivalent stiffness of the pre-compressed spring-type negative stiffness mechanism 2; the lever-type positive stiffness mechanism 3 changes the lever ratio, thereby changing the equivalent stiffness generated by the pre-compressed spring-type negative stiffness mechanism 2 and the lever-type positive stiffness mechanism 3 connected in series.

[0083] The power mechanism is installed between the cable 7 and the ground and is connected to the lever-type positive stiffness mechanism 3 for transmission; it is used to sense the vibration of the cable 7, generate relative motion with it, and drive the lever-type positive stiffness mechanism 3, thereby changing the lever ratio of the lever-type positive stiffness mechanism 3.

[0084] In this embodiment, the mechanical damper 1 is used to suppress the vibration generated by the cable 7. When the installation position coincides with the mode node of a certain higher-order vibration mode, the damper loses its control effect on the vibration of the cable 7 for that mode. At this time, the power mechanism senses the vibration of the cable 7, generates relative motion with it, and drives the lever-type positive stiffness mechanism 3, thereby changing the lever ratio of the lever-type positive stiffness mechanism 3. When the lever ratio of the lever-type positive stiffness mechanism 3 changes, it will change the equivalent stiffness generated by the preloaded spring-type negative stiffness mechanism 2 and the lever-type positive stiffness mechanism 3, thereby changing the local stiffness of the cable 7, and thus changing the control effect of the mechanical damper 1 on the cable 7. When the mechanical damper 1 can suppress the vibration of the cable 7 and the vibration amplitude of the cable 7 is less than the preset vibration amplitude, the power mechanism no longer changes the lever ratio of the lever-type positive stiffness mechanism 3, and the adjustable equivalent stiffness device completes the adjustment of the equivalent stiffness.

[0085] The following benefits can be obtained by adopting this solution:

[0086] 1. This embodiment provides a novel solution for multimodal control of cables based on nodal modes through a purely mechanical structure. It has a wide range of applications and, compared with existing active / semi-active methods that change the dynamic parameters of the damper, it has the characteristic of not requiring external power supply.

[0087] 2. This embodiment adopts a design that connects a preloaded spring negative stiffness mechanism and a lever positive stiffness mechanism in series. By amplifying the equivalent negative stiffness value, the control target is achieved, which effectively reduces the engineering and physical implementation difficulty of the preloaded spring negative stiffness mechanism.

[0088] 3. This embodiment amplifies the vibration response at the damper by changing the local stiffness of the cable, thereby effectively achieving the misalignment of the damper position and the mode node. Compared with other schemes that directly change the installation position of the vibration absorber through adaptive adjustment, it does not require changing the installation position and connection status of the damper, thus ensuring connection reliability.

[0089] Optionally, the preloaded spring type negative stiffness mechanism 2 includes a first outer frame 201, a guide sleeve 202, a guide rod 203, a pair of first spring assemblies 204, a first connector 205, and a second connector 206;

[0090] The first outer frame 201 is fixedly connected to the guide sleeve 202;

[0091] The first end of the guide rod 203 is fixedly connected to the cable 7, and the second end is slidably connected inside the guide sleeve 202;

[0092] The first connector 205 is fixedly connected to the guide rod 203;

[0093] A pair of first spring assemblies 204 are symmetrically arranged along the guide rod 203; one end of the first spring assembly 204 is hinged to the first outer frame 201, and the other end is hinged to the first connecting member 205; when the first spring assembly 204 is in a horizontal position, it is in a pre-compressed state.

[0094] The second connector 206 is fixedly connected to the guide sleeve 202; the second connector 206 is hinged to the lever-type positive stiffness mechanism 3.

[0095] Optionally, the lever-type positive stiffness mechanism 3 includes a second spring assembly 301, a lever 302, a first slider 303, and a support 304;

[0096] The support 304 is installed on the ground;

[0097] The second spring assembly 301 is fixedly connected to the support 304;

[0098] One end of the lever 302 is hinged to the second connector 206, and the other end is hinged to the second spring assembly 301;

[0099] The first slider 303 is slidably connected to the lever 302, and the first slider 303 is connected to the power mechanism. The first slider 303 serves as the fulcrum of the lever 302. When the power mechanism drives the first slider 303 to move, it will change the leverage ratio of the lever 302.

[0100] In this embodiment, the pre-compressed spring negative stiffness mechanism 2 and the lever positive stiffness mechanism 3 work together to generate equivalent stiffness. The lever positive stiffness mechanism 3 is used to amplify the equivalent stiffness of the pre-compressed spring negative stiffness mechanism 2. Furthermore, the lever positive stiffness mechanism 3 changes the lever ratio of the lever 302 by moving the first slider 303, thereby changing the equivalent stiffness generated by the combined action of the pre-compressed spring negative stiffness mechanism 2 and the lever positive stiffness mechanism 3.

[0101] Optionally, the power mechanism includes a mechanical sensing mechanism 4, a mechanical drive mechanism 5, and a mechanical transmission mechanism 6.

[0102] The first end of the mechanical sensing mechanism 4 is installed on the cable 7, and the second end is connected to the mechanical drive mechanism 5. The mechanical drive mechanism 5 is installed on the cable 7. The mechanical transmission mechanism 6 is installed on the ground and is connected to the lever-type positive stiffness mechanism 3 and the mechanical drive mechanism 5 respectively (specifically, the first slider 303 is connected to the mechanical transmission mechanism 6).

[0103] The mechanical sensing mechanism 4 is used to sense the vibration of the cable 7, generate relative motion with it, and drive the mechanical drive mechanism 5, which in turn drives the lever-type positive stiffness mechanism 3 through the mechanical transmission mechanism 6, thereby changing the lever ratio of the lever-type positive stiffness mechanism 3.

[0104] In this embodiment, a mechanical sensing mechanism 4 is used to replace the sensor in the existing active / semi-active damper to realize the sensing of cable vibration; at the same time, a mechanical drive mechanism 5 and a mechanical transmission mechanism 6 are used to replace the actuator to realize the adjustment of the dynamic characteristics of the cable-control system. This avoids the dependence of the sensor and actuator on the external power supply, and is more adaptable to the vibration control needs in complex environments than the previous device.

[0105] Optionally, the mechanical sensing mechanism 4 includes a first mass block 401, a second mass block 402, a third spring 403, a fourth spring 404, a first damping assembly 405, a second damping assembly 406, a first connecting rod 407, a second connecting rod 408, and a slide rail 409.

[0106] One end of the first connecting rod 407 is fixedly connected to the cable 7, and the other end is fixedly connected to the first mass block 401;

[0107] The slide 409 is fixedly connected to the cable 7, and the slide 409 is perpendicular to the cable 7. The first mass block 401 and the second mass block 402 are slidably connected to the slide 409.

[0108] One end of the second connecting rod 408 is fixedly connected to the first mass block 401, and the other end is fixedly connected to the second mass block 402;

[0109] The first damping component 405 is mounted on the first connecting rod 407; the third spring 403 is sleeved on the first damping component 405 and connected in parallel with the first damping component 405;

[0110] The second damping component 406 is mounted on the second connecting rod 408; the fourth spring 404 is sleeved on the second damping component 406 and connected in parallel with the second damping component 406;

[0111] The first mass block 401 is connected to the mechanical drive mechanism 5 for driving the mechanical drive mechanism 5.

[0112] In this embodiment, the mechanical sensing mechanism 4 adopts a two-degree-of-freedom structure to convert the acceleration response of the cable 7 into the displacement response of the first mass block 401. The first mass block 401, the first damping component 405, and the third spring 403 are used to generate a resonance effect to amplify the displacement of the first mass block 401. The second mass block 402, the second damping component 406, and the fourth spring 404 are used to flatten the peak value of the frequency response curve, ensuring that it remains stable within the target frequency range. That is, within the target frequency range, under the same input excitation amplitude, the displacement amplitude output by the first mass block 401 is similar. When the cable 7 vibrates, the first mass block 401 reciprocates along the slide 409, thereby driving the mechanical drive mechanism 5. It should be noted that, due to the resonance effect, the displacement amplitude of the first mass block 401 will be much greater than the vibration amplitude of the cable 7.

[0113] In this embodiment, the mechanical drive mechanism includes a support arm 501, a drive shaft 502, a ratchet 503, a pawl 504, and a V-arm 505;

[0114] The support arm 501 is fixedly connected to the cable 7;

[0115] The drive shaft 502 is rotatably connected to the support arm 501 and the V-arm 505 respectively, and is fixedly connected to the ratchet 503;

[0116] The pawl 504 is fixedly connected to the V-arm 505 and engages with the ratchet 503.

[0117] The V-shaped arm 505 is correspondingly arranged with the first mass block 401, and the first mass block 401 is used to drive the V-shaped arm 505 to rotate along the transmission shaft 502.

[0118] The drive shaft 502 is connected to the mechanical transmission mechanism.

[0119] In this embodiment, when the V-arm 505 is driven by the first mass block 401, it will drive the pawl 504 to rotate, thereby driving the ratchet 503 and the drive shaft 502 to rotate. It should be noted that since the first mass block 401 is reciprocating, when the first mass block 401 moves upward, it will drive the pawl 504 to move into another tooth of the ratchet 503. When the first mass block 401 moves downward, it will drive the pawl 504 to drive the ratchet 503 and the drive shaft 502 to rotate. Therefore, the drive shaft 502 will always rotate in the same direction.

[0120] Optionally, the mechanical transmission mechanism includes a second outer frame 601, a third connecting member 602, a flexible shaft 603, a reciprocating lead screw 604, a second slider 605, a third slider 606, and a slide rail 607.

[0121] The second outer frame 601 is installed on the ground;

[0122] The slide rail 607 is fixedly connected to the second outer frame 601;

[0123] The reciprocating lead screw 604 is rotatably connected to the second outer frame 601;

[0124] The second slider 605 and the third slider 606 are respectively fixedly connected to the third connecting member 602; and the second slider 605 is threadedly connected to the reciprocating lead screw 604, and the third slider 606 is slidably connected to the slide rail 607;

[0125] One end of the flexible shaft 603 is fixedly connected to the transmission shaft 502, and the other end is fixedly connected to the reciprocating lead screw 604;

[0126] The third connector 602 is rotatably connected to the first slider 303.

[0127] In this embodiment, when the drive shaft 502 rotates, the flexible shaft 603 drives the reciprocating screw 604 to rotate, thereby causing the third connecting member 602 and the first slider 303 to move via the second slider 605. The reciprocating screw 604 is existing technology. Since the drive shaft 502 always rotates in the same direction, the reciprocating screw 604 also always rotates in the same direction. When the second slider 605 moves to the end of the reciprocating screw 604, if the reciprocating screw 604 continues to rotate, the second slider 605 will move in the opposite direction. It should also be noted that the flexible shaft 603 is existing technology. Since the mechanical drive mechanism is fixedly connected to the cable 7, when the cable 7 vibrates, the drive shaft 502 will vibrate along with the cable 7. Therefore, the connection between the drive shaft 502 and the reciprocating screw 604 cannot be made using a common rotating shaft. The design of the flexible shaft 603 will eliminate the influence of the vibration of the drive shaft 502.

[0128] Example 2

[0129] This embodiment provides a cable multimodal control method based on a passively adjustable stiffness-damper, employing the cable multimodal control device based on a passively adjustable stiffness-damper described in Embodiment 1, and includes the following steps:

[0130] S1: Determine the installation position and damping coefficient of the mechanical damper 1 based on the damping requirements of the large low-order modal vibration of the cable 7 and the space requirements of the actual application scenario.

[0131] Please refer to Figure 8 Let the length of cable 7 be... The mass of the cable is 7 units of length. The tension acting on both ends of cable 7 is T In the coordinate system shaft and The axes represent the chordal and lateral directions of cable 7, respectively. The lateral displacement response of cable 7 at a certain position is: .

[0132] The natural frequencies of the nth mode of cable 7 are calculated using the following formula. ;

[0133] ;

[0134] In the formula: The length of cable 7; The tension acting at both ends of cable 7; The mass of the cable is 7 units of length;

[0135] Please refer to Figure 8 The mechanical damper 1 is installed near the anchoring end of the cable 7, i.e., the installation position. The selection of this location should take into account the following factors: Mechanical damper 1 is mainly used to control the low-order modal vibration of cable 7, so it is necessary to ensure that mechanical damper 1 has a large relative modal displacement in the low-order modes; at the same time, it should not exceed the installation space limit to ensure safety and ease of installation and maintenance.

[0136] The damping coefficient c of the mechanical damper 1 should be selected based on the core principle of optimizing its additional damping ratio for the dominant vibration mode of the cable 7.

[0137] According to the principles of dynamics, the equation of motion for cable 7 is:

[0138] ;

[0139] in, The force applied to cable 7 by the adjustable equivalent stiffness device; The force applied to the cable 7 by the mechanical damper 1; The equivalent stiffness value of the adjustable equivalent stiffness device; This is an external excitation acting on cable 7; It is the Dirac function; is the damping coefficient of mechanical damper 1; Response to lateral displacement of the cable right The second-order partial derivative, Response to lateral displacement of the cable Regarding time The second-order partial derivative; For cable 7 in the installation position lateral displacement response; For cable 7 in the installation position The lateral displacement response with respect to time The first derivative, i.e., the lateral velocity response;

[0140] S2: Determine the installation position and initial equivalent stiffness value of the adjustable equivalent stiffness device based on the installation position and damping coefficient of the mechanical damper 1, and obtain the nodal mode i of the cable in the initial state, where: i=1,2,...,N; N is the total number of modes; take the nodal mode i and the weakly damped modes near it as the target modes for adaptive adjustment;

[0141] According to the installation position of mechanical damper 1 Determine the nodal modes with only a single mechanical damper 1 installed, near the installation location of the nodal mode shape. The installation position of the adjustable equivalent stiffness device is determined near the antinode. ;

[0142] Take the initial equivalent stiffness value as The initial nodal modes of cable 7 are determined based on the established parameters of mechanical damper 1 and the initial equivalent stiffness value of the adjustable equivalent stiffness device.

[0143] The minimum damping ratio required for cable 7 to resist wind-induced vibration is determined by the Scruton number (a dimensionless key parameter in structural wind-induced vibrations such as vortex-induced vibration and galloping). When the Scruton number is greater than 10, cable 7 no longer experiences wind-induced vibration, which is the minimum damping ratio required for cable 7; the formula is as follows:

[0144] ;

[0145] in, air density; The cable diameter is 7. To achieve the required minimum Scruton number, the modal damping ratio near the initial nodal mode should be less than [a certain value]. Several weakly damped modes are used as target modes for adaptive adjustment.

[0146] S3: Based on the minimum damping ratio requirement that the target mode should meet in engineering practice, determine the stiffness provided by the adjustable equivalent stiffness component required by the target mode to achieve the required minimum damping ratio, thereby determining the adjustable equivalent stiffness range required by the adjustable equivalent stiffness component.

[0147] Combinations of the damping coefficient of mechanical damper 1 with different equivalent stiffness values ​​of the adjustable equivalent stiffness component will yield different additional modal damping ratios for cable 7. The target modal damping ratio should be greater than [a certain value]. To meet the control requirements, determine the required adjustable equivalent stiffness range. Ensure that at least one equivalent stiffness value exists within this range. Make the target modal damping ratio greater than In other words, the passive adjustable stiffness-damper system can adjust the damping ratio of the target mode near the nodal mode to the ideal value required by the project.

[0148] S4: Design the structure and parameters of the mechanical sensing mechanism 4 in the adjustable equivalent stiffness component according to the control target modal coverage frequency range; design the adaptive adjustment trigger threshold according to the engineering vibration control requirements;

[0149] The mounting position of the mechanical sensing component on cable 7 The installation location needs to be close to the adjustable equivalent stiffness device. The response of cable 7 near the installation position of the adjustable equivalent stiffness device is sensed; the acceleration response of cable 7 at the position of mechanical sensing mechanism 4 serves as the input signal. Input mechanical sensing components.

[0150] like Figure 9 The mechanical sensing mechanism shown in the diagram, according to the principles of dynamics, has the following motion equations:

[0151] ;

[0152] in, The relative acceleration vector of the mechanical sensing component with respect to cable 7; The relative velocity vector of the mechanical sensing component with respect to cable 7; This is the relative displacement vector of the mechanical sensing component with respect to cable 7; It is a unit vector; and These are the relative acceleration, relative velocity, and relative displacement of the first mass block relative to cable 7, respectively. and These represent the relative acceleration, relative velocity, and relative displacement of the second mass block relative to cable 7, respectively. The mass matrix of the mechanical sensing component; The damping matrix of the mechanical sensing component; This represents the stiffness matrix of the mechanical sensing component. and Let these be the masses of the first mass block and the second mass block, respectively. and These are the damping coefficients of the first damping component and the second damping component, respectively. and These are the stiffness coefficients of the third and fourth springs, respectively.

[0153] Output the relative displacement of the first mass block transfer function for:

[0154] ;

[0155] in, , The frequency of the input mechanical sensing component.

[0156] To meet the vibration control requirements of cable 7, its expected acceleration response amplitude should not exceed [a certain value]. According to the transfer function Through optimized design of the sensing components, the input amplitude is controlled within the target modal coverage frequency range. The acceleration and output have relatively small differences within the frequency range. Based on this, the corresponding adaptive adjustment trigger threshold is selected. Therefore, when cable 7 is in the installation position... The acceleration amplitude at that point exceeds hour, The first mass block drives the V-arm to start rotating.

[0157] S5: The stay cable vibrates under external load excitation;

[0158] S6: Perform the judgment, specifically:

[0159] If the dynamic characteristics of the mechanical sensing mechanism are lower than the trigger threshold, the target mode does not vibrate significantly and the mechanical drive mechanism is not triggered to operate, that is, the stiffness of the equivalent stiffness component is not triggered to change, and the process returns to S5.

[0160] If the target mode vibrates and the dynamic characteristics of the mechanical sensing mechanism reach the trigger threshold, the mechanical sensing mechanism drives the mechanical drive mechanism to operate, and then the mechanical transmission mechanism converts this motion into a change in equivalent stiffness. The damping ratio of the target mode increases until the dynamic characteristics of the mechanical sensing component fall below the trigger threshold. At this point, the passive self-adjustment process of the equivalent stiffness stops, and the target mode has been effectively controlled. Due to the change in equivalent stiffness, the node mode shifts from node mode i to node mode j, where j = 1, 2, ..., N, and j ≠ i. Node mode j and its nearby weakly damped modes become the new target modes, and the process returns to S5.

[0161] Please refer to Figure 10 The equivalent stiffness is formed by connecting a preloaded spring-type negative stiffness mechanism 2 and a lever-type positive stiffness mechanism 3 in series. The lateral displacement of the cable 7 at the installation position of the preloaded spring-type negative stiffness mechanism 2 is... The displacement at the series connection point of the preloaded spring negative stiffness mechanism 2 and the lever positive stiffness mechanism 3 is .

[0162] When the amplitude of the first mass block exceeds the trigger threshold, the V-arm is driven to swing, thereby driving the pawl to insert into the upper tooth groove of the ratchet, causing the ratchet to rotate through a certain angle. As the V-arm swings continuously, the ratchet performs unidirectional intermittent motion, driving the transmission shaft to rotate unidirectionally, ultimately driving the first slider 303 to move axially along the lever 302, thus realizing the movement of the fulcrum of the lever 302 (the method of how the transmission shaft 502 drives the first slider 303 to move axially along the lever 302 is explained above); this causes a change in the equivalent stiffness, corresponding to an increase in the damping ratio of the modal; please refer to [reference needed]. Figure 11 The vertical restoring force generated by a pair of first spring assemblies 204 The formula is:

[0163] ;

[0164] In the formula: The stiffness coefficient of the spring in the first spring assembly 204; This refers to the free length of the spring in the first spring assembly 204; This refers to the length of the spring in the first spring assembly 204 when compressed to a horizontal position. This represents the displacement of the guide rod;

[0165] By linearly simplifying the negative stiffness generated by the springs in the pair of first spring assemblies 204, we obtain the approximate expression for the negative stiffness and the corresponding restoring force:

[0166] ;

[0167] ;

[0168] In the formula: This represents the approximate negative stiffness of the first spring assembly 204; The restoring force of the first spring assembly 204; The lateral displacement of the cable 7 at the installation position of the preloaded spring type negative stiffness mechanism 2;

[0169] The stiffness coefficient of the spring in the second spring assembly is The length between the fulcrum of lever 302 and the left end of the lever is The length between the fulcrum of lever 302 and the left end of lever 302 is The leverage ratio is The equivalent stiffness of the adjustable equivalent stiffness device and its force expression on cable 7 are as follows:

[0170] ;

[0171] ;

[0172] In the formula: The equivalent stiffness of the adjustable equivalent stiffness device; The force exerted on cable 7 by the equivalent stiffness of the adjustable equivalent stiffness device; This represents the approximate negative stiffness of the first spring assembly 204; This refers to the leverage ratio; This is the stiffness coefficient of the spring in the second spring assembly;

[0173] <0, >0, in Under stability conditions >0, Since the value is less than 0, the equivalent stiffness generated by the preloaded spring negative stiffness mechanism 2 and the lever positive stiffness mechanism 3 is negative.

[0174] The preloaded spring-type negative stiffness mechanism 2 can amplify the local response of the cable 7. During the passive adaptive adjustment process, when the position of the first slider 303 on the lever 302 moves, the lever ratio... z Consequently, the equivalent stiffness generated by the adjustable equivalent stiffness component also changes. k eq This change alters the local stiffness of cable 7, which in turn alters the installation position of mechanical damper 1. The lateral displacement of cable 7 at point 7 causes a change in the control effect of mechanical damper 1. When the second slider moves to the end with the reciprocating screw, a direction switch is achieved at the end transition curve segment, and the change in the lever ratio z also reverses accordingly. Until the lever ratio z is adjusted to a certain value, the relative displacement of the first mass block in the mechanical sensing component is less than the trigger threshold, and the passive adaptive adjustment process terminates. At this time, the target mode has been effectively controlled, and the initial node mode has shifted to other modes.

[0175] Optionally, the mechanical damper 1 is installed on the mode node of the nodal mode under the influence of the initial stiffness value of the adjustable equivalent stiffness device, and the adjustable equivalent stiffness device is installed near the mechanical damper 1.

[0176] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A cable multimodal control device based on a passively adjustable stiffness-damper, characterized in that, include: Mechanical dampers and adjustable equivalent stiffness devices; The mechanical damper is installed between the cable and the ground; The adjustable equivalent stiffness device includes a preloaded spring negative stiffness mechanism, a lever positive stiffness mechanism, and a power mechanism; the preloaded spring negative stiffness mechanism is installed on the cable and is used to change the local stiffness of the cable, thereby changing the control effect of the mechanical damper. The lever-type positive stiffness mechanism is installed on the ground and is connected to the pre-compressed spring-type negative stiffness mechanism for transmission; it is used to amplify the equivalent stiffness of the pre-compressed spring-type negative stiffness mechanism; the lever-type positive stiffness mechanism changes the equivalent stiffness generated by the pre-compressed spring-type negative stiffness mechanism and the lever-type positive stiffness mechanism in series by changing the lever ratio. The power mechanism is installed between the cable and the ground and is connected to the lever-type positive stiffness mechanism for transmission; it is used to sense the vibration of the cable, generate relative motion with it, and drive the lever-type positive stiffness mechanism, thereby changing the lever ratio of the lever-type positive stiffness mechanism. The power mechanism includes a mechanical sensing mechanism, a mechanical drive mechanism, and a mechanical transmission mechanism. The mechanical sensing mechanism includes a first mass block, a second mass block, a third spring, a fourth spring, a first damping assembly, a second damping assembly, a first connecting rod, a second connecting rod, and a slide rail. One end of the first connecting rod is fixedly connected to the cable, and the other end is fixedly connected to the first mass block. The slide rail is fixedly connected to the cable and is perpendicular to the cable. The first mass block and the second mass block are slidably connected to the slide rail. One end of the second connecting rod is fixedly connected to the first mass block, and the other end is fixedly connected to the second mass block. The first damping assembly is mounted on the first connecting rod. The third spring is sleeved on the first damping assembly and connected in parallel with it. The second damping assembly is mounted on the second connecting rod. The fourth spring is sleeved on the second damping assembly and connected in parallel with it. The first mass block is drively connected to the mechanical drive mechanism for driving the mechanical drive mechanism. The mechanical drive mechanism includes a support arm, a drive shaft, a ratchet, a pawl, and a V-arm; the support arm is fixedly connected to the cable; the drive shaft is rotatably connected to the support arm and the V-arm respectively, and is fixedly connected to the ratchet; the pawl is fixedly connected to the V-arm and meshes with the ratchet; the V-arm is correspondingly arranged with the first mass block, and the first mass block is used to drive the V-arm to rotate along the drive shaft; the drive shaft is drively connected to the mechanical transmission mechanism.

2. The cable multimodal control device based on a passively adjustable stiffness-damper as described in claim 1, characterized in that, The preloaded spring type negative stiffness mechanism includes a first outer frame, a guide sleeve, a guide rod, a pair of first spring assemblies, a first connector, and a second connector; The first outer frame is fixedly connected to the guide sleeve; The first end of the guide rod is fixedly connected to the cable, and the second end is slidably connected inside the guide sleeve; The first connector is fixedly connected to the guide rod; A pair of first spring assemblies are symmetrically arranged along the guide rod; one end of the first spring assembly is hinged to the first outer frame, and the other end is hinged to the first connector; when the first spring assembly is in a horizontal position, it is in a pre-compressed state; The second connector is fixedly connected to the guide sleeve; the second connector is hinged to the lever-type positive stiffness mechanism.

3. The cable multimodal control device based on a passively adjustable stiffness-damper as described in claim 2, characterized in that, The lever-type positive stiffness mechanism includes a second spring assembly, a lever, a first slider, and a support; The support is installed on the ground; The second spring assembly is fixedly connected to the support; One end of the lever is hinged to the second connector, and the other end is hinged to the second spring assembly; The first slider is slidably connected to the lever, and the first slider is driven by the power mechanism. The first slider serves as the fulcrum of the lever, and when the power mechanism drives the first slider to move, it will change the lever ratio of the lever.

4. The cable multimodal control device based on a passively adjustable stiffness-damper as described in claim 3, characterized in that, The first end of the mechanical sensing mechanism is mounted on the cable, and the second end is connected to the mechanical drive mechanism; the mechanical drive mechanism is mounted on the cable; the mechanical transmission mechanism is mounted on the ground and is connected to the lever-type positive stiffness mechanism and the mechanical drive mechanism respectively. The mechanical sensing mechanism is used to sense the vibration of the cable, generate relative motion with it, and drive the mechanical drive mechanism, which in turn drives the lever-type positive stiffness mechanism through the mechanical transmission mechanism, thereby changing the lever ratio of the lever-type positive stiffness mechanism.

5. The cable multimodal control device based on a passively adjustable stiffness-damper as described in claim 3, characterized in that, The mechanical transmission mechanism includes a second outer frame, a third connecting member, a flexible shaft, a reciprocating lead screw, a second slider, a third slider, and a slide rail; The second outer frame is installed on the ground; The slide rail is fixedly connected to the second outer frame; The reciprocating lead screw is rotatably connected to the second outer frame; The second slider and the third slider are respectively fixedly connected to the third connecting member; and the second slider is threadedly connected to the reciprocating lead screw, while the third slider is slidably connected to the slide rail; One end of the flexible shaft is fixedly connected to the transmission shaft, and the other end is fixedly connected to the reciprocating lead screw; The third connector is rotatably connected to the first slider.

6. A cable multimodal control method based on a passively adjustable stiffness-damper, characterized in that, The cable multimodal control device based on a passively adjustable stiffness-damper as described in any one of claims 1-5 includes the following steps: S1: Determine the installation position and damping coefficient of the mechanical damper based on the damping requirements of the large-amplitude low-order modal vibration of the cable and the space requirements of the actual application scenario; S2: Determine the installation position and initial equivalent stiffness value of the adjustable equivalent stiffness device based on the installation position and damping coefficient of the mechanical damper, and obtain the nodal mode i of the cable in the initial state, where: i=1,2,...,N; N is the total number of modes; take nodal mode i and the weakly damped modes near it as the target modes for adaptive adjustment; S3: Based on the minimum damping ratio requirement that the target mode should meet in engineering practice, determine the stiffness provided by the adjustable equivalent stiffness component required by the target mode to achieve the required minimum damping ratio, thereby determining the adjustable equivalent stiffness range required by the adjustable equivalent stiffness component. S4: Design the structure and parameters of the mechanical sensing mechanism in the adjustable equivalent stiffness component according to the frequency range of the control target modal coverage; design the adaptively adjustable trigger threshold according to the engineering vibration control requirements; S5: The stay cable vibrates under external load excitation; S6: Perform the judgment, specifically: If the dynamic characteristics of the mechanical sensing mechanism are lower than the trigger threshold, the target mode does not vibrate significantly and the mechanical drive mechanism is not triggered to operate, that is, the stiffness of the equivalent stiffness component is not triggered to change, and the process returns to S5. If the target mode vibrates and the dynamic characteristics of the mechanical sensing mechanism reach the trigger threshold, the mechanical sensing mechanism drives the mechanical drive mechanism to operate, and then the mechanical transmission mechanism converts this motion into a change in equivalent stiffness. The damping ratio of the target mode increases until the dynamic characteristics of the mechanical sensing component fall below the trigger threshold. At this point, the passive self-adjustment process of the equivalent stiffness stops, and the target mode has been effectively controlled. Due to the change in equivalent stiffness, the node mode shifts from node mode i to node mode j, where j = 1, 2, ..., N, and j ≠ i. Node mode j and its nearby weakly damped modes become the new target modes, and the process returns to S5.

7. The cable multimodal control method based on a passively adjustable stiffness-damper as described in claim 6, characterized in that, The mechanical damper is installed on the mode node of the nodal mode under the influence of the initial stiffness value of the adjustable equivalent stiffness device, and the adjustable equivalent stiffness device is installed near the mechanical damper.

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