Spatial parallel mechanism with passive flexible supporting legs and method

Abstract

The invention discloses a spatial parallel mechanism with passive flexible supporting legs and a method, solves the problem of limited layout space of a parallel mechanism in the prior art, and has the beneficial effects that a first supporting leg and a second supporting leg are reasonably arranged, and the layout reasonability is improved. A plurality of first supporting legs are connected between the movable platform and the fixed platform and incline outwards relative to the central axis of the fixed platform, a first support is arranged on the side, facing the movable platform, of the fixed platform and exceeds the movable platform, a second support is arranged on the movable platform, and a second supporting leg is arranged between the first support and the second support. The second supporting legs are arranged between every two adjacent first supporting legs, the second supporting legs are located on the side, away from the fixed platform, of the movable platform, and the first supporting legs and the second supporting legs are passive flexible components.

Description

Technical Field

[0001] The present invention relates to the technical field of parallel mechanisms, in particular to a spatial parallel mechanism with passive compliant legs and a method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Parallel mechanisms are widely used in precision manipulation, minimally invasive surgery, and space docking due to their high stiffness, high dynamic responsiveness, and high-precision control capabilities. A typical six-degree-of-freedom parallel mechanism usually consists of a fixed platform and a moving platform, which are connected by multiple branches to achieve spatial posture control. The problems with this structure are:

[0004] When the moving platform is subjected to force, it transmits and transfers the force through rigid rods and flexible rods. However, in many cases, the space between the moving platform and the fixed platform is limited. Arranging the rigid rods and flexible rods using only the space between the two platforms makes it difficult to arrange the various structural components.

[0005] The rigid rod and the flexible rod are both arranged in an inwardly inclined manner relative to the fixed platform, further making the space between the moving platform and the fixed platform smaller;

[0006] Traditional parallel mechanisms have a strong structural rigidity and lack an effective compliance adjustment mechanism when faced with complex and uncertain external contact or disturbances. This makes it difficult to achieve a flexible response to external forces, limiting their adaptability in human-machine collaboration and complex operating environments.

[0007] Existing parallel mechanisms are mostly focused on optimizing motion performance, which results in a failure to take into account mechanical balance in all directions during structural design. This causes the overall stiffness of the mechanism to exhibit significant anisotropy, making it prone to local deformation or stiffness bottlenecks under the action of multi-directional external forces.

[0008] Some mechanisms attempt to introduce compliant structures in their designs to improve compliance, but this often sacrifices overall stiffness control and motion decoupling capabilities, making it difficult to simultaneously achieve high precision, high compliance, and isotropically uniform structural performance. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a spatial parallel mechanism with passive flexible legs, which utilizes the space on both sides of the dynamic platform to achieve a reasonable layout of the first leg and the second leg, effectively absorb the load and improve the rationality of the layout.

[0010] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0011] A spatial parallel mechanism with passive flexible legs includes a fixed platform, a moving platform is arranged on one side of the fixed platform, a distance is set between the moving platform and the fixed platform, multiple first legs are connected between the moving platform and the fixed platform, the first legs are arranged to be inclined outward relative to the central axis of the fixed platform, a first bracket is arranged on the side of the fixed platform facing the moving platform, the first bracket is arranged beyond the moving platform, a second bracket is arranged at the moving platform, a second leg is arranged between the first bracket and the second bracket, the second leg is arranged in multiple locations, the second leg is arranged between two adjacent first legs, the second leg is located on the side of the moving platform away from the fixed platform, and the first leg and the second leg are both passive flexible components.

[0012] As described above, the parallel mechanism has a reasonable arrangement of the first leg, and the second leg is fixed to the side of the moving platform away from the fixed platform through the first bracket and the second bracket. The space on the side of the moving platform away from the fixed platform is utilized instead of only utilizing the space between the moving platform and the fixed platform to arrange the first leg and the second leg. The structure is reasonably arranged, the structural parts are reasonably laid out, and the space utilization rate is improved.

[0013] As described above, for the spatial parallel mechanism with passively compliant legs, in order to ensure the stability and balance of the structural arrangement, the plurality of second legs are located in the same plane, and two adjacent second legs are spaced apart at a set angle.

[0014] As described above, the spatial parallel mechanism with passive flexible legs is reasonably arranged. The moving platform includes a support plate, and an extension section is arranged on the peripheral side of the support plate. The extension section is connected to one end of the first leg. The extension section supports the second bracket. The first bracket is located on the outer side of the support plate. The first bracket is set at a distance from the support plate. The setting of the extension section not only ensures that the first leg supports the moving platform, but also can support the second leg, making space for the setting of the first bracket and ensuring a reasonable area of the moving platform.

[0015] As described above, the spatial parallel mechanism with passively compliant legs, the plane where the first legs are located is perpendicular to the fixed platform, the interval between two adjacent first legs is set at a set angle, and the first legs and the second bracket are staggered.

[0016] As described above, the spatial parallel mechanism with passive compliant legs is configured to facilitate processing and manufacturing, wherein the first bracket is a first support column, the second bracket is a second support column, the first support column is vertically connected to the fixed platform, and the second support column is vertically connected to the moving platform.

[0017] As described above, the spatial parallel mechanism with passively compliant legs, the first leg and the second leg have the same structure, the first leg includes a guide cylinder, one end of the guide cylinder is movable relative to the movable sleeve, the other end of the guide cylinder is connected to the fixed platform, the movable rod passes through the movable sleeve and is located inside the guide cylinder, the movable rod is fixedly connected to the movable sleeve, springs are provided on the outside and inside of the guide cylinder, the internal spring is circumferentially sleeved on the movable rod, the setting of the guide cylinder makes the parallel mechanism have a certain rigidity, springs are provided on the inside and outside of the guide cylinder, the passive flexibility of the first leg and the second leg is improved, bidirectional compliant response is achieved, plastic deformation of the first connecting rod and the second connecting rod is avoided, and the overall rigidity is ensured.

[0018] As described above, the spatial parallel mechanism with passively compliant legs, the end of the first leg fixed to the fixed platform is the first joint, the end of the first leg fixed to the moving platform is the second joint, with the center of the moving platform as the center of the circle, the radius of the circle where the first joint is located is smaller than the radius of the circle where the projection point of the second joint on the moving platform is located, and the radius of the circle where the projection point of the second joint on the moving platform is located is determined by the rotational stiffness.

[0019] In the spatial parallel mechanism with passively compliant legs as described above, the height between the second joint and the fixed platform is determined by the radius of the circle on which the projection point of the first joint on the moving platform lies and the radius of the circle on which the projection point of the second joint on the moving platform lies;

[0020] The height between the second leg and the fixed platform at both ends is determined by the radius of the circle where the projection point of the first joint on the moving platform is located and the radius of the circle where the projection point of the second joint on the moving platform is located.

[0021] In the spatial parallel mechanism with passively compliant legs as described above, one end of the second leg fixed to the first bracket is a third joint, one end of the second leg fixed to the second bracket is a fourth joint, an angle between a line connecting a projection point of the third joint on the moving platform and a center point of the moving platform and a line on which the projection of the first leg on the moving platform lies is a first angle, and an angle between a line connecting a projection point of the fourth joint on the moving platform and the center point of the moving platform and a line on which the projection of the first leg on the moving platform lies is a second angle;

[0022] The radius of the circle where the projection point of the third joint on the moving platform is located is determined by the determined rotational stiffness, the first angle, the second angle, and the radius of the circle where the projection point of the fourth joint on the moving platform is located.

[0023] In a second aspect, the present invention provides a method for operating a spatial parallel mechanism having passively compliant legs, including the following:

[0024] The fixed platform is fixed, and the moving platform is located on the upper side of the fixed platform;

[0025] When the dynamic platform is subjected to a tensile load or a compressive load, the first leg and the second leg are stretched or compressed. The first leg and the second leg are both passive flexible parts and have passive flexibility to effectively absorb the load.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1) The parallel mechanism provided by the present invention has a reasonable arrangement of the first leg, and the second leg is fixed to the side of the moving platform away from the fixed platform through the first bracket and the second bracket. The space on the side of the moving platform away from the fixed platform is utilized instead of only utilizing the space between the moving platform and the fixed platform to arrange the first leg and the second leg. The structure is reasonably arranged, the structural parts are reasonably arranged, and the space utilization rate is improved. The first leg is arranged obliquely, and the second leg is parallel to the moving platform. The two are arranged in different directions to effectively absorb loads in different directions.

[0028] 2) In the present invention, the first support leg is arranged outwardly with respect to the center of the fixed platform, which is beneficial to expanding the area of the moving platform and ensuring the stability of the support for the moving platform. At the same time, it is beneficial to the arrangement of the first bracket and the second bracket, facilitates the arrangement of the second support leg, and reserves a larger space for the center of the moving platform.

[0029] 3) The structure of the movable platform in the present invention is reasonably arranged. The movable platform includes a support plate, and an extension section is arranged around the support plate. The arrangement of the extension section not only facilitates the connection between the first leg and the movable platform, but also realizes the support of the second bracket. The arrangement of the extension section prevents the support plate from being too large, which is conducive to the first bracket being arranged on the outside of the support plate and facilitates the arrangement of the second leg.

[0030] 4) In the present invention, the first leg and the second leg are rationally arranged. When the moving platform is subjected to loads in all directions, since the first leg and the second leg are both passive compliant parts, the moving platform can quickly absorb the loads in the X, Y and Z directions, thereby improving the response capability.

[0031] 5) In the present invention, the radius of the circle where the projection point of the second joint on the moving platform is located is determined by the rotational stiffness, and the height of the two ends of the second leg relative to the fixed platform is further determined by the radius of the circle where the projection point of the first joint on the moving platform and the radius of the circle where the projection point of the second joint on the moving platform are located. The radius of the circle where the projection point of the fourth joint on the moving platform is located is determined by the determined rotational stiffness, the first angle, the second angle, and the radius of the circle where the projection point of the third joint on the moving platform is located, and the decoupling conditions of the Cartesian stiffness matrix are met, so that the established parallel mechanism can achieve isotropy of stiffness. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1 Schematic diagram of a spatial parallel mechanism with passively compliant legs according to one or more embodiments of the present invention Figure 1 .

[0034] Figure 2 Schematic diagram of a spatial parallel mechanism with passively compliant legs according to one or more embodiments of the present invention Figure 2 .

[0035] Figure 3 1 is a top view of a spatial parallel mechanism with passively compliant legs according to one or more embodiments of the present invention.

[0036] Figure 4 Schematic diagram of the first leg or the second leg in a spatial parallel mechanism with passively compliant legs according to one or more embodiments of the present invention.

[0037] In the figure: the distances or sizes between parts are exaggerated to show the positions of various parts, and the schematic diagram is for reference only.

[0038] Among them: 1. First support leg, 2. Second support leg, 3. Fixed platform, 4. Moving platform, 5. Extension section, 6. First bracket, 7. Second bracket, 8. Fan-shaped section, 9. Protruding strip, 10. Support plate, 11. Guide cylinder, 12. Moving rod, 13. Moving sleeve, 14. Fixed sleeve, 15. Internal spring, 16. External spring, 17. First limit end, 18. Second limit end, 19. Third limit end, 20. External moving gasket. DETAILED DESCRIPTION

[0039] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise clearly indicated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprising" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations;

[0041] As introduced in the background art, the parallel mechanism in the prior art does not fully utilize the space. In order to solve the above technical problem, the present invention proposes a spatial parallel mechanism with passively compliant legs.

[0042] Example 1

[0043] In a typical embodiment of the present invention, referring to Figure 1 and Figure 2 As shown, a spatial parallel mechanism with passive compliant legs includes a fixed platform 3, a moving platform 4 is arranged on one side of the fixed platform 3, and a distance is set between the moving platform 4 and the fixed platform 3. A plurality of first legs 1 are connected between the moving platform 4 and the fixed platform 3, and the first leg 1 is inclined outward relative to the central axis of the fixed platform 3. A first bracket 6 is arranged on the side of the fixed platform 3 facing the moving platform 4, and the first bracket 6 is arranged beyond the moving platform 4. A second bracket 7 is arranged at the moving platform 4, and a second leg 2 is arranged between the first bracket 6 and the second bracket 7. The second leg 2 is provided in multiple locations, and the second leg 2 is arranged between two adjacent first legs 1. The second leg 2 is located on the side of the moving platform 4 away from the fixed platform 3. The first leg 1 and the second leg 2 are both passive compliant components.

[0044] It is easy to understand that the plane where the first leg 1 is located is set perpendicular to the fixed platform, the interval between two adjacent first legs 1 is set at a set angle, the first leg 1 can realize the load in the X direction and the Z direction, and the first leg 1 is staggered with the second bracket 7. In this embodiment, three first legs 1 are set, and the interval between two adjacent first legs 1 is 120°.

[0045] To ensure the stability and balance of the structural setting, multiple second legs 2 are located in the same plane. The second legs 2 are provided with three interval setting angles between two adjacent second legs 2. The extension and retraction directions of the second legs 2 are arranged parallel to the moving platform 4. The second legs 2 cooperate with the first leg 1, so that the moving platform can quickly absorb X, Y and Z direction loads and improve the response capability.

[0046] For a reasonable layout, the moving platform 4 includes a support plate 10, and an extension section 5 is arranged on the side of the support plate 10. The extension section 5 is plate-shaped, and the thickness of the extension section 5 is consistent with the thickness of the support plate 10. The extension section 5 is connected to one end of the first leg, and the extension section supports the second bracket 7. The first bracket 6 is located on the outside of the support plate 10, and the first bracket 6 is set at a distance from the support plate 10. The setting of the extension section 5 not only ensures that the first leg 1 supports the moving platform 4, but also can support the second leg 2, making space for the setting of the first bracket and ensuring a reasonable area of the moving platform.

[0047] Specifically, the extension section 5 includes a fan-shaped segment 8, the inner side of the fan-shaped segment 8 is connected to the peripheral side of the support plate 10, and a protruding strip 9 is provided on the outer side of the fan-shaped segment 8. The protruding strip 9 extends outward along the plane where the fan-shaped segment 8 is located. The protruding strip 9 is connected to the top side of the first leg 1, and the side of the fan-shaped segment 8 away from the protruding strip 9 is connected to one end of the second leg 2.

[0048] In this embodiment, for the convenience of processing and manufacturing, the first bracket 6 is the first support column, the second bracket 7 is the second support column, the first support column is vertically connected to the fixed platform, and the second support column is vertically connected to the movable platform. The height of the first support column is greater than the height of the second support column. The cross-section of the first support column can be trapezoidal, and the narrower side of the first support column is set toward the central axis of the movable platform.

[0049] It is easy to understand that both ends of the first leg 1 are connected to the fixed platform 3 and the movable platform 4 through ball joints and ball joint seats, and both ends of the second leg 2 are connected to the sides of the first bracket 6 and the second bracket 7 through ball joints and ball joint seats respectively.

[0050] refer to Figure 4 As shown, the first leg 1 and the second leg 2 have the same structure. The first leg includes a guide cylinder 11. One end of the guide cylinder 11 is movable relative to the movable sleeve 13. The other end of the guide cylinder 11 is connected to the fixed platform. The movable rod 12 passes through the movable sleeve 13 and is located inside the guide cylinder 11. The movable rod 12 is fixedly connected to the movable sleeve 13. Springs are provided on the outside and inside of the guide cylinder 11. The internal spring is circumferentially sleeved on the movable rod 12. The setting of the guide cylinder 11 makes the parallel mechanism have a certain rigidity. Springs are provided on the inside and outside of the guide cylinder 11 to improve the passive flexibility of the first leg 1 and the second leg 2, realize bidirectional flexible response, avoid plastic deformation of the first leg 1 and the second leg 2, and ensure the overall rigidity.

[0051] In this embodiment, a first limiting end 17 is provided at one end of the guide cylinder 11, and the first limiting end 17 is connected to the fixed sleeve 17, and the fixed sleeve 17 is connected to the fixed rod. The first limiting end 17 limits one end of the external spring 16, and an external moving gasket 20 is provided at the end of the movable sleeve 13 close to the movable cylinder. The external moving gasket 20 can contact the external spring 16 to limit one end of the external spring; when the first leg or the second leg is subjected to a compressive load, the movable rod drives the movable sleeve to compress the external spring relative to the guide cylinder to absorb the compressive load.

[0052] A second limiting end 18 is provided at the other end of the guide cylinder 11. The second limiting end can be a circular ring structure. The second limiting end 18 contacts the internal spring 15 to limit one end of the internal spring 15. The moving rod 12 is provided through the second limiting end 18. The end of the moving rod 12 located in the guide cylinder 11 is provided with a third limiting end 19. The other end of the internal spring is limited by the third limiting end 19. When the first leg 1 or the second leg 2 is subjected to a tensile load, the moving rod 12 drives the moving sleeve 13 to move relative to the guide cylinder 11, compressing the internal spring 15 to absorb the tensile load.

[0053] In this embodiment, the guide cylinder 11 includes two sections, one of which is arranged close to the movable sleeve 13, and the other is arranged close to the fixed sleeve. The length of the guide cylinder 11 close to the movable sleeve 13 is greater than the length of the other section, and the inner diameter of the guide cylinder close to the fixed sleeve 17 is greater than the inner diameter of the other section, so that a limiting step is formed between the two guide cylinders 11 to limit the movement of the movable rod.

[0054] Among them, the moving rod of the first leg 1 is connected to the moving platform 4, and the moving rod 12 of the second leg 2 is connected to the side of the second bracket; the fixed rod and the moving rod are respectively connected to the corresponding ball joint seat through a ball joint, and the ball joint seat is fixed to the moving platform or the fixed platform.

[0055] It is easy to understand that the first leg 1 and the second leg 2 may also adopt other passive compliance components.

[0056] refer to Figure 3 As shown, one end of the first leg 1 fixed to the fixed platform is the first joint ( Figure 3 b1, b3 and b5), the first leg is fixed to one end of the moving platform as the second joint ( Figure 3 p1, p3 and p5 in the figure), with the center of the moving platform as the center, the radius of the circle where the first joint is located is r a1 Smaller than the radius r of the circle where the projection point of the second joint on the moving platform is located b1 , the radius r of the circle where the projection point of the second joint on the moving platform is located b1 From the rotational stiffness k o Sure.

[0057]

[0058] In this way, the rotational stiffness κ0 is determined according to actual needs, and the radius r of the circle where the projection point of the second joint on the moving platform 2 is located is determined according to formula (1): b1 ; Then according to formula (2) r a1 <r b1 Select the radius r of the circle where the projection point of the first joint on the moving platform is located a1 ;

[0059]

[0060] One end of the second leg 2 fixed to the first bracket 6 is the third joint ( Figure 3 b2, b4 and b6), one end of the second leg 2 fixed to the second bracket 7 is the fourth joint ( Figure 3p2, p4 and p6 in the figure), the height between the second joint and the fixed platform, that is, the height h3 between the third joint and the hinge point of the first bracket and the fixed platform, and the height h2 between the fourth joint and the hinge point of the second bracket and the fixed platform are determined by the radius of the circle where the projection point of the first joint on the moving platform lies and the radius of the circle where the projection point of the second joint on the moving platform lies, the height h3 between the third joint and the hinge point of the first bracket and the fixed platform 3, and the height h2 between the fourth joint and the hinge point of the second bracket and the fixed platform;

[0061] Thus, according to formula (2), the height h1 between the second joint and the fixed platform 3, the height h3 between the third joint and the hinge point of the first bracket and the fixed platform 3, and the height h2 between the fourth joint and the hinge point of the second bracket and the fixed platform are determined. The height h1 between the second joint and the fixed platform 3 is lower than the height h3 between the third joint and the hinge point of the first bracket and the fixed platform 3.

[0062] In addition, the angle between the line connecting the projection point of the third joint on the moving platform and the center point of the moving platform and the straight line on which the projection of the first link on the moving platform lies is a first angle θ1, and the angle between the line connecting the projection point of the fourth joint on the moving platform and the center point of the moving platform and the straight line on which the projection of the first link on the moving platform lies is a second angle θ2;

[0063]

[0064] First, select one of the first angle θ1 and the second angle θ2, and determine the other one according to formula (4);

[0065] First select the radius r of the circle where the projection point of the fourth joint on the moving platform is located b2 According to formula (3), the radius r of the circle where the projection point of the third joint on the moving platform is located is determined by the determined rotational stiffness, the first angle, the second angle, and the radius of the circle where the projection point of the third joint on the moving platform is located. a2 .

[0066] The acquisition of the above-mentioned related parameters is based on the Jacobian matrix and satisfies the Cartesian stiffness matrix, so that the established parallel robot can achieve isotropic stiffness.

[0067] The parallel mechanism provided in this embodiment has a reasonable arrangement of the first leg 1, and the second leg 2 is fixed to the side of the moving platform 4 away from the fixed platform 3 through the first bracket 6 and the second bracket 7. The space on the side of the moving platform 4 away from the fixed platform 3 is used instead of only the space between the moving platform 4 and the fixed platform 3 to arrange the first leg 1 and the second leg 2. The moving platform 4 is provided with an extension section 5, which facilitates the arrangement of the first leg 1 and the second bracket 7. The overall structure is reasonably arranged, the structural parts are reasonably arranged, and the space utilization rate is improved. The first leg 1 and the second leg 2 are passive flexible components with flexibility and strong adaptability, realizing bidirectional flexible response, avoiding plastic deformation of the first connecting rod and the second connecting rod, and ensuring the overall stiffness. Moreover, the position of each joint is determined by a formula so that the parameters satisfy the Cartesian stiffness, thereby enabling the parallel mechanism to achieve isotropic stiffness and effectively perform decoupling.

[0068] Example 2

[0069] This embodiment discloses a working method of a spatial parallel mechanism with passively compliant legs, including the following contents:

[0070] The fixed platform is fixed, and the moving platform is located on the upper side of the fixed platform;

[0071] When the dynamic platform is subjected to a tensile load or a compressive load, the first leg and the second leg are stretched or compressed. The first leg and the second leg are both passive flexible parts and have passive flexibility to effectively absorb the load.

[0072] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A spatial parallel mechanism with passively compliant legs, comprising a fixed platform, a moving platform disposed on one side of the fixed platform, and a distance between the moving platform and the fixed platform, characterized in that: Multiple first legs are connected between the moving platform and the fixed platform, and the first legs are arranged to be inclined outward relative to the central axis of the fixed platform. A first bracket is arranged on the side of the fixed platform facing the moving platform, and the first bracket is arranged beyond the moving platform. A second bracket is arranged at the moving platform, and a second leg is arranged between the first bracket and the second bracket. The second leg is arranged in multiple places, and the second leg is arranged between two adjacent first legs. The second leg is located on the side of the moving platform away from the fixed platform. The first leg and the second leg are both passive flexible components.

2. The spatial parallel mechanism with passively compliant legs according to claim 1, characterized in that: The plurality of second legs are located in the same plane, two adjacent second legs are spaced apart at a set angle, and the extension and retraction directions of the second legs are parallel to the movable platform.

3. The spatial parallel mechanism with passively compliant legs according to claim 1, characterized in that: The moving platform includes a support plate, an extension section is arranged on the peripheral side of the support plate, the extension section is connected to one end of the first leg, the extension section supports the second bracket, the first bracket is located on the outside of the support plate, and the first bracket is set at a distance from the support plate.

4. The spatial parallel mechanism with passively compliant legs according to claim 1, characterized in that: The plane where the first legs are located is perpendicular to the fixed platform, the interval between two adjacent first legs is set at a set angle, the inclination angle of the first legs relative to the fixed platform is 45°-70°, and the first legs are staggered with the second bracket.

5. The spatial parallel mechanism with passively compliant legs according to claim 1, characterized in that: The first bracket is a first supporting column, the second bracket is a second supporting column, the first supporting column is vertically connected to the fixed platform, and the second supporting column is vertically connected to the moving platform.

6. The spatial parallel mechanism with passively compliant legs according to claim 3, characterized in that: The first leg and the second leg have the same structure. The first leg includes a guide cylinder, one end of which is movable relative to the movable sleeve, and the other end of the guide cylinder is connected to the fixed platform. The movable rod passes through the movable sleeve and is located inside the guide cylinder. The movable rod is fixedly connected to the movable sleeve. Springs are provided on the outside and inside of the guide cylinder, and the internal spring is circumferentially sleeved on the movable rod.

7. The spatial parallel mechanism with passively compliant legs according to claim 1, characterized in that: One end of the first leg fixed to the fixed platform is the first joint, and one end of the first leg fixed to the moving platform is the second joint. With the center of the moving platform as the center of the circle, the radius of the circle where the first joint is located is smaller than the radius of the circle where the projection point of the second joint on the moving platform is located, and the radius of the circle where the projection point of the second joint on the moving platform is located is determined by the rotational stiffness.

8. The spatial parallel mechanism with passively compliant legs according to claim 7, characterized in that: The height between the second joint and the fixed platform is determined by the radius of the circle where the projection point of the first joint on the moving platform is located and the radius of the circle where the projection point of the second joint on the moving platform is located; The height between the second leg and the fixed platform at both ends is determined by the radius of the circle where the projection point of the first joint on the moving platform is located and the radius of the circle where the projection point of the second joint on the moving platform is located.

9. The spatial parallel mechanism with passively compliant legs according to claim 7, characterized in that: One end of the second leg fixed to the first bracket is a third joint, and one end of the second leg fixed to the second bracket is a fourth joint. The angle between the line connecting the projection point of the third joint on the moving platform and the center point of the moving platform and the straight line on which the projection of the first connecting rod on the moving platform lies is a first angle. The angle between the line connecting the projection point of the fourth joint on the moving platform and the center point of the moving platform and the straight line on which the projection of the first connecting rod on the moving platform lies is a second angle. The radius of the circle where the projection point of the third joint on the moving platform is located is determined by the determined rotational stiffness, the first angle, the second angle, and the radius of the circle where the projection point of the fourth joint on the moving platform is located.

10. The operating method of the spatial parallel mechanism with passively compliant legs according to any one of claims 1 to 9, characterized in that: Includes the following: The fixed platform is fixed, and the moving platform is located on the upper side of the fixed platform; When the dynamic platform is subjected to a tensile load or a compressive load, the first leg and the second leg are stretched or compressed. The first leg and the second leg are both passive flexible parts and have passive flexibility to effectively absorb the load.

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