A six-degree-of-freedom adaptive adjustable stiffness device

Abstract

The present invention discloses a six-degree-of-freedom adaptive adjustable variable stiffness device, comprising an upper platform, an upper mounting angle seat, a single-degree-of-freedom adaptive adjustable variable stiffness mechanism, a lower mounting angle seat and a lower platform. The upper end of the single-degree-of-freedom adaptive adjustable variable stiffness mechanism is connected to the upper platform via the upper mounting angle seat, and the lower end of the single-degree-of-freedom adaptive adjustable variable stiffness mechanism is connected to the lower platform via the lower mounting angle seat. The upper and lower constant force mechanism modules are symmetrically installed with respect to the stiffness switch module. The variable stiffness device structure is based on a multi-degree-of-freedom parallel configuration, utilizes a constant force mechanism, and reversibly realizes the static balance of the device through the reverse constant force principle. Switching the stiffness switch can turn on and off the static balance, so that the device can effectively switch between high stiffness and low stiffness configurations to realize variable stiffness.

Description

Technical Field

[0001] The invention relates to the technical field of variable stiffness, in particular to a six-degree-of-freedom self-adaptive adjustable variable stiffness device. Background Art

[0002] With the development of science and technology and the emergence of emerging disciplines, many fields such as industrial production, medical equipment, and space exploration have put forward higher requirements for the field of variable stiffness. For example, variable stiffness devices have gradually become a hot research field in the field of robotics research. Since it can change its own stiffness according to different needs, it can improve the safety of human-computer interaction, especially in occasions with close contact with people, such as the service industry and the medical industry. Due to its broad prospects, more and more people are beginning to study variable stiffness devices. Therefore, a more powerful and adaptable variable stiffness device plays an irreplaceable role. A device with an automatically adjustable variable stiffness function can support, limit and protect objects in a high stiffness state, and can also achieve vibration reduction of objects in a low stiffness state.

[0003] There are two types of adjustable stiffness mechanisms: passive adjustment and active adjustment. In terms of active stiffness, an additional drive is generally used to control the stiffness adjustable switch to achieve real-time stiffness adjustment. In terms of passive stiffness, magnetic attraction, manual adjustment and other methods are mainly used. The disadvantage is that the stiffness of the device cannot be adjusted in real time. However, the structure of the general stiffness variable device is large, and the external energy required for active adjustment is large. In addition, the control device is also more complicated, so its application is not as extensive as passive adjustment.

[0004] The patent specification with publication number CN109968397B discloses an adaptive passive variable stiffness joint, which is mainly used to solve the problems of large joint size and slow response of current variable stiffness joints. Its structure is that the arm and the joint are connected, and the inside of the arm is a four-bar mechanism. The joint includes a joint shell and a lever and a slider moving mechanism inside the shell. The lever is connected to the connecting rod through the slider. The connecting rod transmits gravity information to the slider to display its position information. The movement of the slider changes the distribution information of the force at both ends of the lever, thereby changing the overall stiffness of the joint and realizing adjustable stiffness. Summary of the invention

[0005] The purpose of the present invention is to provide a six-degree-of-freedom adaptive adjustable variable stiffness device to solve the problems existing in the above-mentioned prior art. The structure of the variable stiffness device is based on a multi-degree-of-freedom parallel configuration, and utilizes a constant force mechanism to reversibly achieve the static balance of the device through the reverse constant force principle. Switching the stiffness switch can turn the static balance on and off, so that the device can effectively switch between high stiffness and low stiffness configurations to achieve variable stiffness.

[0006] To achieve the above object, the present invention provides the following solution: The present invention provides a six-degree-of-freedom adaptive adjustable stiffness device, comprising

[0007] An upper platform, the upper platform is used to contact the load, the bottom surface of the upper platform is provided with three first grooves and three second grooves, the circumference of the inner three first grooves and the circumference of the outer three second grooves are concentric circles, and the middle of the first groove and the second groove are provided with threaded through holes; and

[0008] An installation angle seat, the installation angle seat comprises an upper installation angle seat and a lower installation angle seat of the same structure, each of the first groove and the second groove is connected to the upper installation angle seat by a countersunk bolt, and the bottom of the upper installation angle seat is connected to the bearing column of the single-degree-of-freedom adaptive adjustable stiffness mechanism; and

[0009] A single-degree-of-freedom adaptive adjustable stiffness mechanism, the single-degree-of-freedom adaptive adjustable stiffness mechanism comprises a bearing column, an upper cover, a cylindrical shell, a lower cover, a constant force mechanism module and a stiffness switch module, the upper cover and the bearing column are sequentially installed on the top of the cylindrical shell, the lower cover is installed on the bottom of the cylindrical shell, the inner cavity of the cylindrical shell is provided with two constant force mechanism modules, and the two constant force mechanism modules are connected through the stiffness switch module; the constant force mechanism module comprises a short leaf spring, an auxiliary mounting block, a long leaf spring and a connecting column, the connecting column comprises a large cylindrical end, a small cylindrical end and a large cylindrical end connected in sequence in an integral manner, and the two ends of the short leaf spring are respectively used to connect with the large cylindrical end and the cylindrical outer end of the connecting column The inner and outer sides of the connecting rod are connected to the shell, the two ends of the long leaf spring are respectively connected to the small cylindrical end of the connecting column and the cylindrical shell, and the two ends of the short leaf spring and the long leaf spring are welded with the auxiliary mounting blocks; the stiffness switch module comprises a connecting rod, an inner support beam mounting plate, a support beam and an outer support beam mounting plate, the disk of the connecting rod is connected to the connecting column of the constant force mechanism module at the lower end, the inner support beam mounting plates are installed on both sides of the straight rod of the connecting rod, and the outer support beam mounting plates are symmetrically arranged on both sides of the connecting rod, and the two ends of the support beam are respectively welded to the inner support beam mounting plate and the outer support beam mounting plate; the disk of the outer support beam mounting plate is fixedly connected to the connecting column of the upper constant force mechanism module; and

[0010] A lower platform, the lower platform is used to contact the foundation, and the top surface of the lower platform is provided with three third grooves and three fourth grooves, the circumference of the three inner third grooves and the circumference of the three outer fourth grooves are concentric circles, and threaded through holes are provided in the middle of the third grooves and the fourth grooves, and each of the third grooves and the fourth grooves is connected to the lower mounting angle seat by a countersunk bolt.

[0011] In one embodiment, the centers of the upper platform and the lower platform are on a vertical line, the diameter of the circle where the first groove is located is the same as the diameter of the circle where the third groove is located, and the diameter of the circle where the second groove is located is the same as the diameter of the circle where the fourth groove is located.

[0012] In one embodiment, the main body of the upper platform includes a central platform, a connecting plate and an arc-shaped platform, a plurality of connecting plates are evenly connected to the central platform in the circumferential direction, and the arc-shaped platform is fixed to the end of the connecting plate; the circumference of the inner arc line and the circumference of the outer arc line of the arc-shaped platform are both concentrically arranged with the central platform.

[0013] In one of the embodiments, the upper mounting angle seat includes a bottom sphere and a chamfered surface located on one side of the top of the bottom sphere, and threaded holes are formed on the bottom sphere and the chamfered surface.

[0014] In one of the embodiments, each of the first groove and the second groove is connected to the bottom sphere of the upper mounting angle seat through a countersunk bolt, and the chamfered surface of the upper mounting angle seat is connected to the bearing column of the single-degree-of-freedom adaptive adjustable stiffness mechanism through a stud.

[0015] In one embodiment, each of the third groove and the fourth groove is connected to the bottom sphere of the lower mounting angle seat through a countersunk bolt, and the chamfered surface of the lower mounting angle seat is connected to the lower cover of the single-degree-of-freedom adaptive adjustable stiffness mechanism through a stud.

[0016] In one embodiment, the lower end of the supporting column is welded to the connecting column of the constant force mechanism module at the upper end; a through hole with a diameter larger than the diameter of the supporting column is opened at the upper end of the upper cover, and four threaded through holes are opened on the circumference of the lower end of the upper cover.

[0017] In one of the embodiments, the cylindrical shell is provided with four threaded holes at each of its upper and lower ends, and the threaded holes at the upper and lower ends of the cylindrical shell are respectively used to be fixedly connected to the upper cover and the lower cover by screws; the outer side of the cylindrical shell is provided with a plurality of threaded through holes for being fixedly connected to the auxiliary mounting blocks welded to the short leaf spring and the long leaf spring by bolts.

[0018] In one of the embodiments, the disk of the connecting rod is provided with two threaded through holes, and the disk of the connecting rod is connected to the upper end of the connecting column of the constant force mechanism module at the lower end by bolts; the straight rod of the connecting rod is provided with two threaded through holes, and the straight rod of the connecting rod is connected to the inner support beam mounting plate by bolts; the disk of the outer support beam mounting plate is provided with two threaded through holes, and the disk of the outer support beam mounting plate is fixedly connected to the upper end of the connecting column of the constant force mechanism module at the upper end by bolts.

[0019] In one embodiment, the single-degree-of-freedom adaptive adjustable stiffness mechanism includes a single-degree-of-freedom adaptive adjustable stiffness mechanism 1, a single-degree-of-freedom adaptive adjustable stiffness mechanism 2, a single-degree-of-freedom adaptive adjustable stiffness mechanism 3, a single-degree-of-freedom adaptive adjustable stiffness mechanism 4, a single-degree-of-freedom adaptive adjustable stiffness mechanism 5 and a single-degree-of-freedom adaptive adjustable stiffness mechanism 6; the first groove includes a first groove 1, a first groove 2 and a first groove 3; the second groove includes a second groove 1, a second groove 2 and a second groove 3; the third groove includes a third groove 1, a third groove 2 and a third groove 3; the fourth groove includes a fourth groove 1, a fourth groove 2 and a third groove 3; the upper and lower ends of the single-degree-of-freedom adaptive adjustable stiffness mechanism 1 are respectively assembled in the first groove 1 and the fourth groove 1 through the upper mounting angle seat and the lower mounting angle seat; The upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism two are respectively assembled in the second groove one and the third groove one through the upper mounting angle seat and the lower mounting angle seat, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism three are respectively assembled in the first groove two and the fourth groove two through the upper mounting angle seat and the lower mounting angle seat, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism four are respectively assembled in the second groove two and the third groove two through the upper mounting angle seat and the lower mounting angle seat, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism five are respectively assembled in the first groove three and the fourth groove three through the upper mounting angle seat and the lower mounting angle seat, and the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism six are respectively assembled in the second groove three and the third groove three through the upper mounting angle seat and the lower mounting angle seat.

[0020] Compared with the prior art, the present invention has achieved the following beneficial technical effects:

[0021] The six-degree-of-freedom adaptive variable stiffness device of the present invention comprises an upper platform, an upper mounting angle seat, a single-degree-of-freedom adaptive variable stiffness mechanism, a lower mounting angle seat and a lower platform. The upper end of the single-degree-of-freedom adaptive variable stiffness mechanism is connected to the upper platform via the upper mounting angle seat, and the lower end of the single-degree-of-freedom adaptive variable stiffness mechanism is connected to the lower platform via the lower mounting angle seat. The structure of the variable stiffness device is based on a multi-degree-of-freedom parallel configuration, and utilizes a constant force mechanism to reversibly achieve static balance of the device through the reverse constant force principle. Switching the stiffness switch can turn the static balance on and off, thereby enabling the device to effectively switch between high stiffness and low stiffness configurations to achieve variable stiffness. The upper and lower constant force mechanism modules are installed symmetrically about the stiffness switch module, and the displacement variable U is set. When the displacement generated by the single-degree-of-freedom adaptive adjustable stiffness mechanism is less than the set displacement variable U, the stiffness switch module is in a closed state, and the device is in an adjustable high-stiffness structure form, which can achieve support, limitation and protection for the object; when the displacement generated by the single-degree-of-freedom adaptive adjustable stiffness mechanism is greater than the set displacement variable U, the stiffness switch module will automatically open, and the device is in an adjustable low-stiffness structure form. This structure can be used to suppress the influence of external disturbances on the normal operation of the equipment and achieve vibration reduction on the object. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2(a) is a schematic diagram of the upper platform structure of the present invention;

[0025] Figure 2(b) is a schematic diagram of the lower platform structure of the present invention;

[0026] FIG3( a ) is a schematic diagram of installing a corner seat in the present invention;

[0027] FIG3( b ) is a cross-sectional view of the installation angle seat in the present invention;

[0028] FIG4( a ) is a schematic diagram of a single-degree-of-freedom adaptive variable stiffness mechanism in the present invention;

[0029] FIG4( b ) is a cross-sectional view of the single-degree-of-freedom adaptive adjustable stiffness mechanism of the present invention;

[0030] FIG5( a ) is a schematic diagram of the closed state of the stiffness switch module in the present invention;

[0031] FIG5( b ) is a schematic diagram of the stiffness switch module in the present invention in an open state;

[0032] FIG6( a ) is a schematic diagram of a high-rigidity structure of a constant force mechanism in the present invention;

[0033] FIG6( b ) is a schematic diagram of a low-rigidity structure of a constant force mechanism in the present invention;

[0034] Among them, 1-upper platform; 2-upper mounting angle seat; 3-double-headed stud; 4-single-degree-of-freedom adaptively adjustable stiffness mechanism; 41-single-degree-of-freedom adaptively adjustable stiffness mechanism one; 42-single-degree-of-freedom adaptively adjustable stiffness mechanism two; 43-single-degree-of-freedom adaptively adjustable stiffness mechanism three; 44-single-degree-of-freedom adaptively adjustable stiffness mechanism four; 45-single-degree-of-freedom adaptively adjustable stiffness mechanism five; 46-single-degree-of-freedom adaptively adjustable stiffness mechanism six; 5-lower mounting angle seat; 6-lower platform; 7-bearing column; 8-upper cover; 9-short leaf spring; 10-auxiliary mounting block; 11-long leaf spring; 12-connecting column; 13-connecting rod, 14 inner support beam mounting plate; 15-support beam; 16-outer support beam mounting plate; 17-cylindrical shell; 18-lower cover. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide a six-degree-of-freedom adaptive adjustable variable stiffness device to solve the problems existing in the above-mentioned prior art. The structure of the variable stiffness device is based on a multi-degree-of-freedom parallel configuration, and utilizes a constant force mechanism to reversibly achieve the static balance of the device through the reverse constant force principle. Switching the stiffness switch can turn the static balance on and off, so that the device can effectively switch between high stiffness and low stiffness configurations to achieve variable stiffness.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1-Figure 6(b)As shown, the present invention provides a six-degree-of-freedom adaptive variable stiffness device, including an upper platform 1, an upper mounting angle seat 2, a stud 3, a single-degree-of-freedom adaptive variable stiffness mechanism 4, a lower mounting angle seat 5 and a lower platform 6. The entire structure is relatively compact, with a small space occupation area, low equipment manufacturing and maintenance costs, and convenient parts replacement. Parts can be replaced according to actual application scenarios to change the stiffness of the device system. The six-degree-of-freedom adaptive variable stiffness device based on concentric circles described in the present invention has two structural forms of adjustable stiffness, namely an adjustable high stiffness structural form and an adjustable low stiffness structural form. The static balance of the device is closed and opened by controlling the stiffness switch module, thereby realizing the switching of the high stiffness structure and the low stiffness structure of the device.

[0039] Attached Figure 2(a)-2(b) They are schematic diagrams of the upper platform structure and the lower platform structure in the present invention, respectively. The upper platform 1 of the present invention is similar to a cylinder and is used to contact the load. The lower platform 6 is an irregular octagonal cylinder and is used to contact the foundation. Six grooves are opened on the end faces of the upper platform 1 and the lower platform 6. The circumference of the inner three grooves and the circumference of the outer three grooves are concentric circles. A threaded through hole is opened in the middle of each groove, which is connected to the upper mounting angle seat 2 and the lower mounting angle seat 5 respectively by countersunk bolts. The concentric circle structure installation allows the single-degree-of-freedom adaptive adjustable stiffness mechanism 4 to be installed symmetrically in pairs, ensuring that each single-degree-of-freedom adaptive adjustable stiffness mechanism 4 is loaded evenly when the device is loaded.

[0040] Attached Figure 3(a)-3(b) The schematic diagram and cross-sectional diagram of the mounting angle seat in the present invention. The mounting angle seat described in the present invention is a sphere with a beveled surface and a bottom surface cut out, which can make the force transmission direction in the single-degree-of-freedom adaptive adjustable stiffness mechanism not along the vertical line, and can realize the natural decoupling of the space cube. The mounting angle seat has threaded holes on the beveled surface and the bottom end surface. The beveled surface of the upper mounting angle seat 2 is connected to the bearing column 7 in the single-degree-of-freedom adaptive adjustable stiffness mechanism 4 through a stud 3, and the bottom end surface is connected to the upper platform 1 through a countersunk bolt. The beveled surface of the lower mounting angle seat 5 is connected to the lower cover 18 through a stud 3, and the bottom end surface is connected to the lower platform 6 through a countersunk bolt. The upper and lower mounting angle seats can be used interchangeably.

[0041] Attached Figure 4(a)-4(b)The schematic diagram and cross-sectional diagram of the single-degree-of-freedom adaptive variable stiffness mechanism in the present invention. There are six single-degree-of-freedom adaptive variable stiffness mechanisms 4, namely, single-degree-of-freedom adaptive variable stiffness mechanism 1 41, single-degree-of-freedom adaptive variable stiffness mechanism 2 42, single-degree-of-freedom adaptive variable stiffness mechanism 3 43, single-degree-of-freedom adaptive variable stiffness mechanism 4 44, single-degree-of-freedom adaptive variable stiffness mechanism 5 45 and single-degree-of-freedom adaptive variable stiffness mechanism 6 46. The first groove includes the first groove 1, the first groove 2 and the first groove 3, the second groove includes the second groove 1, the second groove 2 and the second groove 3, the third groove includes the third groove 1, the third groove 2 and the third groove 3, the fourth groove includes the fourth groove 1, the fourth groove 2 and the third groove 3, and the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism 1 41 are respectively mounted in the first groove 1 and the fourth groove through the upper mounting angle seat 2 and the lower mounting angle seat 5. In groove one, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism 2 42 are respectively assembled in the second groove one and the third groove one through the upper mounting angle seat 2 and the lower mounting angle seat 5, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism 3 43 are respectively assembled in the first groove two and the fourth groove two through the upper mounting angle seat 2 and the lower mounting angle seat 5, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism 44 are respectively assembled in the second groove two and the third groove two through the upper mounting angle seat 2 and the lower mounting angle seat 5, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism 5 45 are respectively assembled in the first groove three and the fourth groove three through the upper mounting angle seat 2 and the lower mounting angle seat 5, and the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism 6 46 are respectively assembled in the second groove three and the third groove three through the upper mounting angle seat 2 and the lower mounting angle seat 5.

[0042] The single-degree-of-freedom adaptive variable stiffness mechanism of the present invention comprises a bearing column 7, an upper cover 8, a cylindrical shell 17, a lower cover 18, a constant force mechanism module and a stiffness switch module. The constant force mechanism module comprises a short leaf spring 9, an auxiliary mounting block 10, a long leaf spring 11 and a connecting column 12. The stiffness switch module comprises a connecting rod 13, an inner support beam mounting plate 14, a support beam 15 and an outer support beam mounting plate 16. The six single-degree-of-freedom adaptive variable stiffness mechanisms 4 of the present invention are fixedly connected to the upper and lower mounting angle seats through studs 3. A threaded hole is opened at the upper end of the bearing column 7, which is connected to the upper mounting angle seat 2 through the studs 3, and the lower end is welded to the upper constant force mechanism module. The upper end of the upper cover 8 has a through hole slightly larger than the diameter of the bearing column 7, which is used to install the bearing column 7 and limit it. The lower end of the upper cover 8 has four threaded through holes on the circumference, which are connected to the cylindrical shell 17 by screws. The upper and lower ends of the cylindrical shell 17 each have four threaded holes, which are used to be fixedly connected to the upper cover 8 and the lower cover 18 by screws. The outer side of the cylindrical shell 17 has a number of threaded through holes, which are used to be fixedly connected to the auxiliary mounting block 10 welded to the short leaf spring 9 and the long leaf spring 11 by bolts. The cylindrical shell 17 has a total of 48 threaded through holes on the outer side of the cylinder, which are used to be connected to the auxiliary mounting block 10 welded to the long leaf spring 11 by bolts.

[0043] Figure 6 (a)-(b) are schematic diagrams of the high-rigidity structure and the low-rigidity structure of the constant force mechanism in the present invention. The constant force mechanism module of the present invention comprises a short leaf spring 9, an auxiliary mounting block 10, a long leaf spring 11 and a connecting column 12. The upper and lower ends of the short leaf spring 9 are respectively welded to the auxiliary mounting block 10, and the auxiliary mounting block 10 has two threaded through holes, which are respectively used to connect to the large cylindrical end of the connecting column 12 and the cylindrical shell 17. The upper and lower ends of the long leaf spring 11 are also respectively welded to the auxiliary mounting block 10, and the auxiliary mounting block 10 has two threaded through holes, which are respectively connected to the small cylindrical end of the connecting column 12 and the cylindrical shell 17 by bolts.

[0044] Specifically, there are two constant force mechanism modules in the present invention, which are symmetrically installed with respect to the stiffness switch module. Each constant force mechanism module is composed of eight short leaf springs 9, four long leaf springs 11 and a connecting column 12. Every two short leaf springs 9 and one long leaf spring 11 form a group, and each group is distributed at 90° on the outside of the connecting column 12. The two sides of the short leaf springs 9 and the long leaf springs 11 are respectively welded to the auxiliary mounting blocks 10, and the auxiliary mounting blocks 10 are provided with threaded through holes. The auxiliary mounting blocks 10 on one side are fixedly connected to the connecting column 12 by bolts, and the auxiliary mounting blocks 10 on the other side are fixedly connected to the cylindrical housing 17 by bolts. The cylinders at both ends of the connecting column 12 are large in size, and the cylinders in the middle are small in size. The large cylinders at both ends and the small cylinders in the middle are each provided with eight threaded holes on the outside. The cylinders at both ends are fixedly connected to the auxiliary mounting blocks 10 of the short leaf springs 9 by bolts, and the cylinders in the middle are fixedly connected to the auxiliary mounting blocks 10 of the long leaf springs 11 by bolts.

[0045] The short leaf spring 9 and the long leaf spring 11 are convenient to disassemble and easy to replace. By replacing the short leaf spring 9 and the long leaf spring 11, the stiffness of the device can be easily adjusted. When the stiffness switch is closed, the short leaf spring 9 and the long leaf spring 11 in the constant force mechanism are both in a bent state. Assuming that the leaf spring of the lower constant force mechanism is bent downward and the leaf spring of the upper constant force mechanism is bent upward, the lower constant force mechanism will generate an upward constant force and the upper constant force mechanism will generate a downward constant force. The lower constant force mechanism and the upper constant force mechanism are connected in parallel through the stiffness switch module, and the static balance of the device is closed, that is, the device is in an adjustable high stiffness structure; when the stiffness switch is turned on, the short leaf spring 9 in the constant force mechanism is in a vertical state and the long leaf spring 11 is in a bent state. Therefore, the short leaf spring 9 provides positive stiffness, and the long leaf spring 11 provides negative stiffness due to load bending. The stiffness provided by the long leaf spring 11 and the short leaf spring 9 meets the stiffness superposition principle. At this time, the upper constant force mechanism and the lower constant force mechanism are both in a low stiffness state, and the device is in a static balance state, that is, the device is in an adjustable low stiffness structure.

[0046] Specifically, Figure 6(a) shows that when the stiffness switch module is closed, that is, the device is in static equilibrium, the short leaf spring 9 and the long leaf spring 11 are both in a bent state, and the constant force mechanism will generate a constant force in one direction to prevent movement in this direction opposite to the generated constant force. This device is installed by installing two upper and lower constant force mechanisms, and symmetrically installed about the stiffness switch module, so that the directions of the constant forces generated are opposite, thereby preventing the movement of the bearing column 7, making the entire device difficult to move, and making it in an adjustable high stiffness structure. This structure can support, limit and protect objects. FIG6(b) shows when the stiffness switch module is turned on, that is, the static balance of the device is closed, the short leaf spring 9 is in a vertical state, providing positive support stiffness, and the long leaf spring 11 is in a bent state, generating negative stiffness in the axial direction of the bearing column 7 for the six-degree-of-freedom adaptive adjustable stiffness device. The short leaf spring 9 and the long leaf spring 11 satisfy the stiffness superposition principle, so the stiffness of the constant force mechanism is reduced, and a quasi-zero stiffness state can be reached. Both the upper constant force mechanism and the lower constant force mechanism are in a low-stiffness structural form. Therefore, the stiffness of the six-degree-of-freedom adaptive adjustable stiffness device is reduced, and is in an adjustable low-stiffness structural form. This structure mainly realizes the vibration reduction effect on the object.

[0047] Figure 5 (a)-(b) is a schematic diagram of the closed state and the open state of the stiffness switch module in the present invention. The stiffness switch module of the present invention comprises a connecting rod 13, an inner support beam mounting plate 14, a support beam 15 and an outer support beam mounting plate 16. The stiffness switch module is used to control the opening and closing of the static balance of the device, thereby realizing the switching of the adjustable stiffness structure of the device. When the stiffness switch is closed, the static balance of the device is closed, and the adjustable stiffness structure is a high stiffness structure. When the stiffness switch is opened, the device is in static balance, and the adjustable stiffness structure is a low stiffness structure.

[0048] The lower disk of the connecting rod 13 has two threaded through holes, which are connected to the upper end of the connecting column 12 in the lower constant force mechanism by bolts. The upper straight rod has two threaded through holes, which are connected to the inner support beam mounting plate 14 by bolts. The two sides of the support beam 15 are welded to the inner support beam mounting plate 14 and the outer support beam mounting plate 16 respectively. The inner support beam mounting plate 14 has a threaded through hole on both sides, which are connected to the connecting rod 13 and the inner support beam mounting plate 14 on the other side by bolts. The upper disk of the outer support beam mounting plate 16 has two threaded through holes, which are fixedly connected to the upper end of the connecting column 12 in the upper constant force mechanism by bolts.

[0049] Specifically, there are four stiffness switch modules in the present invention, each of which includes two outer support beam mounting plates 16, two inner support beam mounting plates 14, six support beams 15 and a connecting rod 13. The support beams 15 are grouped into three pieces, and the two sides of each group of support beams 15 are welded to the outer support beam mounting plates 16 and the inner support beam mounting plates 14 respectively. The upper circular chassis of the outer support beam mounting plates 16 has two threaded through holes, which are fixedly connected to the upper constant force mechanism by bolts. The upper and lower sides of the inner support beam mounting plates 14 each have a threaded through hole, which is fixedly connected to the connecting rod 13 by bolts. The lower circular chassis of the connecting rod 13 has two threaded through holes, which are fixedly connected to the lower constant force mechanism by bolts. The stiffness switch module is easy to replace, and the stiffness of the support beam can be selected according to actual needs, and then different displacement variables U can be set to control the automatic switching of the stiffness switch module. The stiffness switch module of the present invention can be opened and closed manually, and can also be automatically opened to adjust the stiffness structure of the system. The automatic opening is achieved by setting the displacement variable U by selecting the stiffness of the support beam 15. When the single-degree-of-freedom adaptive adjustable stiffness mechanism is subjected to a large impact and the resulting displacement variable is greater than U, the stiffness switch module will automatically open to reduce the stiffness of the device, provide buffering, and thus play a protective role.

[0050] The device of the present invention is based on a multi-degree-of-freedom parallel configuration and is composed of six identical single-degree-of-freedom adaptive variable stiffness mechanisms 4. The automatic variable stiffness mechanism can be adjusted to two structural forms of low stiffness and high stiffness, thereby forming an adjustable variable stiffness mechanism. The high stiffness structural form is mainly used for supporting, limiting and protecting objects, and the low stiffness structural form is mainly used to suppress the influence of external disturbances on the normal operation of the equipment.

[0051] The device of the present invention is adaptive and adjustable and can protect objects and devices. By selecting the stiffness of the support beam 15 and then setting the displacement variable U, when the stiffness switch module is closed and the device is in a high-rigidity structure, if the displacement variable generated by the single-degree-of-freedom adaptive adjustable stiffness mechanism after bearing the load is greater than the set displacement variable U, the stiffness switch module will automatically open and the device will automatically adjust to a low-rigidity structure to play a buffering and protective role.

[0052] The single-degree-of-freedom adaptive variable stiffness mechanism 4 in the present invention adopts a concentric circle installation structure, which allows the single-degree-of-freedom adaptive variable stiffness mechanism 4 to be installed symmetrically in pairs, ensuring that each single-degree-of-freedom adaptive variable stiffness mechanism is loaded evenly when the device is loaded. The constant force mechanism in the single-degree-of-freedom adaptive variable stiffness mechanism 4 satisfies the reverse constant force principle, and the static balance of the switching device is achieved through this principle. The constant force mechanism can also be used as a vibration reduction device to attenuate vibration transmission energy while meeting the system stiffness.

[0053] In the adaptive adjustable stiffness structure of the present invention, the first structure is a high stiffness structure. When the stiffness switch of this structure is closed, that is, the short leaf spring 9 and the long leaf spring 11 in the constant force mechanism are both in a bent state, and when the static balance of the device is closed, the lower end constant force mechanism provides an upward constant force to prevent the load-bearing column 7 from moving downward, and the upper end constant force mechanism provides a downward constant force to prevent the load-bearing column 7 from moving upward, thereby making the entire device difficult to move and being in a high stiffness structure. This structure can support, limit and protect objects. The second stiffness structure is a low stiffness structure. When the stiffness switch is turned on, that is, the short leaf spring 9 in the constant force mechanism is in a vertical state, and the long leaf spring 11 is in a bent state, and the device is in static equilibrium, the short leaf spring 9 provides positive stiffness, and the long leaf spring 11 provides negative stiffness due to loading and bending. The stiffness provided by the long leaf spring 11 and the short leaf spring 9 meets the stiffness superposition principle. Therefore, the stiffness of the constant force mechanism is reduced and can reach a quasi-zero stiffness state. Both the upper constant force mechanism and the lower constant force mechanism are in a low stiffness state, that is, the device is in a low stiffness structure. This structure mainly realizes the vibration reduction effect on the object.

[0054] The short leaf spring 9, the long leaf spring 11 and the support beam 15 in the present invention are connected to other components by bolts using the auxiliary mounting block 10, so they are easy to replace. The stiffness of the components can be adjusted by changing the size and material of the components, thereby changing the stiffness of the system and achieving adjustable stiffness. The connecting parts of the present invention are fixedly connected by bolts and screws, ensuring the reliability of the overall device.

[0055] The concentric circle-based six-degree-of-freedom adaptive adjustable stiffness device of the present invention has a simple structure, stable operation, low manufacturing and maintenance costs, and convenient structural replacement, and can effectively achieve the functions of fixed support, limiting, protection and suppression of natural frequency.

[0056] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure mark in the claims should not be regarded as limiting the claims involved.

[0057] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A six-degree-of-freedom adaptive adjustable stiffness device, characterized in that: include An upper platform, the upper platform is used to contact the load, the bottom surface of the upper platform is provided with three first grooves and three second grooves, the circumference of the inner three first grooves and the circumference of the outer three second grooves are concentric circles, and the middle of the first groove and the second groove are provided with threaded through holes; and An installation angle seat, the installation angle seat comprises an upper installation angle seat and a lower installation angle seat of the same structure, each of the first groove and the second groove is connected to the upper installation angle seat by a countersunk bolt, and the bottom of the upper installation angle seat is connected to the bearing column of the single-degree-of-freedom adaptive adjustable stiffness mechanism; and A single-degree-of-freedom adaptive adjustable stiffness mechanism, the single-degree-of-freedom adaptive adjustable stiffness mechanism comprises a bearing column, an upper cover, a cylindrical shell, a lower cover, a constant force mechanism module and a stiffness switch module, the upper cover and the bearing column are sequentially installed on the top of the cylindrical shell, the lower cover is installed on the bottom of the cylindrical shell, the inner cavity of the cylindrical shell is provided with two constant force mechanism modules, and the two constant force mechanism modules are connected through the stiffness switch module; the constant force mechanism module comprises a short leaf spring, an auxiliary mounting block, a long leaf spring and a connecting column, the connecting column comprises a large cylindrical end, a small cylindrical end and a large cylindrical end connected in sequence in an integral manner, and the two ends of the short leaf spring are respectively used to connect with the large cylindrical end and the cylindrical outer end of the connecting column The inner and outer sides of the connecting rod are connected to the shell, the two ends of the long leaf spring are respectively connected to the small cylindrical end of the connecting column and the cylindrical shell, and the two ends of the short leaf spring and the long leaf spring are welded with the auxiliary mounting blocks; the stiffness switch module comprises a connecting rod, an inner support beam mounting plate, a support beam and an outer support beam mounting plate, the disk of the connecting rod is connected to the connecting column of the constant force mechanism module at the lower end, the inner support beam mounting plates are installed on both sides of the straight rod of the connecting rod, and the outer support beam mounting plates are symmetrically arranged on both sides of the connecting rod, and the two ends of the support beam are respectively welded to the inner support beam mounting plate and the outer support beam mounting plate; the disk of the outer support beam mounting plate is fixedly connected to the connecting column of the upper constant force mechanism module; and A lower platform, the lower platform is used to contact the foundation, and the top surface of the lower platform is provided with three third grooves and three fourth grooves, the circumference of the three inner third grooves and the circumference of the three outer fourth grooves are concentric circles, and threaded through holes are provided in the middle of the third grooves and the fourth grooves, and each of the third grooves and the fourth grooves is connected to the lower mounting angle seat by a countersunk bolt.

2. The six-degree-of-freedom adaptive variable stiffness device according to claim 1, characterized in that: The centers of the upper platform and the lower platform are on a vertical line, the diameter of the circle where the first groove is located is the same as the diameter of the circle where the third groove is located, and the diameter of the circle where the second groove is located is the same as the diameter of the circle where the fourth groove is located.

3. The six-degree-of-freedom adaptive variable stiffness device according to claim 1, characterized in that: The main body of the upper platform includes a central platform, a connecting plate and an arc-shaped platform. The central platform is evenly connected to a plurality of connecting plates in the circumferential direction, and the arc-shaped platform is fixed to the end of the connecting plate. The circumference of the inner arc line and the circumference of the outer arc line of the arc-shaped platform are both concentrically arranged with the central platform.

4. The six-degree-of-freedom adaptive variable stiffness device according to claim 1, characterized in that: The upper mounting angle seat comprises a bottom sphere and an oblique cut surface located on one side of the top of the bottom sphere, and threaded holes are provided on the bottom sphere and the oblique cut surface.

5. The six-degree-of-freedom adaptive variable stiffness device according to claim 4, characterized in that: Each of the first groove and the second groove is connected to the bottom sphere of the upper mounting angle seat through a countersunk bolt, and the chamfered surface of the upper mounting angle seat is connected to the bearing column of the single-degree-of-freedom adaptive adjustable stiffness mechanism through a stud.

6. The six-degree-of-freedom adaptive variable stiffness device according to claim 4, characterized in that: Each of the third groove and the fourth groove is connected to the bottom sphere of the lower mounting angle seat through a countersunk bolt, and the chamfered surface of the lower mounting angle seat is connected to the lower cover of the single-degree-of-freedom adaptive adjustable stiffness mechanism through a stud.

7. The six-degree-of-freedom adaptive variable stiffness device according to claim 1, characterized in that: The lower end of the bearing column is welded to the connecting column of the constant force mechanism module at the upper end; the upper end of the upper cover is provided with a through hole with a diameter larger than the diameter of the bearing column, and the lower end of the upper cover is provided with four threaded through holes on its circumference.

8. The six-degree-of-freedom adaptive variable stiffness device according to claim 7, characterized in that: The upper and lower ends of the cylindrical shell are each provided with four threaded holes, and the threaded holes at the upper and lower ends of the cylindrical shell are respectively used to be fixedly connected to the upper cover and the lower cover by screws; the outer side of the cylindrical shell is provided with a plurality of threaded through holes for being fixedly connected to the auxiliary mounting blocks welded to the short leaf spring and the long leaf spring by bolts.

9. The six-degree-of-freedom adaptive variable stiffness device according to claim 1, characterized in that: The connecting rod has two threaded through holes on its disc, which is connected to the upper end of the connecting column of the constant force mechanism module at the lower end by bolts; the connecting rod has two threaded through holes on its straight rod, which is connected to the inner support beam mounting plate by bolts; the outer support beam mounting plate has two threaded through holes on its disc, which is fixedly connected to the upper end of the connecting column of the constant force mechanism module at the upper end by bolts.

10. The six-degree-of-freedom adaptive variable stiffness device according to claim 1, characterized in that: The single-degree-of-freedom adaptive adjustable stiffness mechanism includes a single-degree-of-freedom adaptive adjustable stiffness mechanism 1, a single-degree-of-freedom adaptive adjustable stiffness mechanism 2, a single-degree-of-freedom adaptive adjustable stiffness mechanism 3, a single-degree-of-freedom adaptive adjustable stiffness mechanism 4, a single-degree-of-freedom adaptive adjustable stiffness mechanism 5 and a single-degree-of-freedom adaptive adjustable stiffness mechanism 6, and any two single-degree-of-freedom adaptive adjustable stiffness mechanisms are parallel or perpendicular to each other in space; the first groove includes a first groove 1, a first groove 2 and a first groove 3, the second groove includes a second groove 1, a second groove 2 and a second groove 3, the third groove includes a third groove 1, a third groove 2 and a third groove 3, the fourth groove includes a fourth groove 1, a fourth groove 2 and a third groove 3, the upper and lower ends of the single-degree-of-freedom adaptive adjustable stiffness mechanism 1 are respectively assembled on the first groove through the upper mounting angle seat and the lower mounting angle seat In groove one and the fourth groove one, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism two are respectively assembled in the second groove one and the third groove one through the upper mounting angle seat and the lower mounting angle seat, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism three are respectively assembled in the first groove two and the fourth groove two through the upper mounting angle seat and the lower mounting angle seat, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism four are respectively assembled in the second groove two and the third groove two through the upper mounting angle seat and the lower mounting angle seat, the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism five are respectively assembled in the first groove three and the fourth groove three through the upper mounting angle seat and the lower mounting angle seat, and the upper and lower ends of the single-degree-of-freedom adaptive variable stiffness mechanism six are respectively assembled in the second groove three and the third groove three through the upper mounting angle seat and the lower mounting angle seat.

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