A load-uniform active suction cup array based on a bistable structure

Abstract

The present invention relates to the field of grasping by an array-type gripper and the design of a bistable structure, and particularly to a load-uniform active suction cup array based on a bistable structure, comprising: a conformable elastic base, a sheet-shaped load-bearing beam-type bistable structure capable of automatic resetting, an active suction cup, and a layer-blocking variable stiffness structure. The bistable structures are fixedly arranged in an array form on the front surface of the elastic base, and an active suction cup is mounted and connected to each bistable structure. The layer-blocking variable stiffness structure is arranged on the back surface of the elastic base in a vertical and horizontal arrangement. The present invention has a suction cup array that can undergo conformable deformation according to the complex concave and convex undulation characteristics and curvature characteristics of the surface of the target object, and the suction cups can actively fit the surface of the target object. Moreover, the shape of the conformable suction cup array is maintained through the layer-blocking variable stiffness structure, realizing load uniformity and enhancing the ability of non-destructive adsorption, grasping, and manipulation of the target object.

Description

Technical Field

[0001] The present invention relates to the fields of array gripper grasping and bistable structure design, and particularly to a load-uniform active suction cup array based on a bistable structure. Background Art

[0002] Robots are playing an increasingly important role in application scenarios such as industrial production and domestic service. The end effector of a robot, as the main interface between the robot and the use environment and the target object, how to improve its non-destructive grasping ability is an important factor in evaluating the performance indicators of the robot. To achieve non-destructive grasping and interaction of large-sized fragile objects or flexible surface objects, using an array of active suction cup grippers is a more practical and favored method. Currently, there are some array active suction cups, such as the agricultural product sorting robot launched by FANUC in Japan, the large mobile robot platform of Loxin in Spain, and the automotive glass assembly robot of KUKA in Germany. However, these active suction cup arrays all use a rigid frame to fix the active suction cup structure, and there is a problem of relatively high requirements for the flatness of the adsorption surface of the target object. When targeting a target object with complex concave-convex undulating features and a large curvature on the surface, the active suction cup array with a rigid frame is prone to phenomena such as uneven load distribution and overly concentrated adsorption area, and it is difficult to achieve non-destructive grasping. Although there are also related designs that use a spring-sleeve structure imitating the suspension structure of a motor vehicle to form an array to solve the problem of uneven load distribution of the active suction cup array, in this solution, the spring telescopic mechanism has a tendency to reset when compressed, resulting in a tendency for the target object to detach from the adsorption, which limits the bearing capacity and stability of the adsorption and grasping. Summary of the Invention

[0003] In order to solve the above technical problems existing in the prior art, the present invention proposes a load-uniform active suction cup array based on a bistable structure, which is an active suction cup array that introduces a bistable structure, a conformable deformable elastic base, and a layer-blocking variable stiffness structure, aiming to improve the grasping and manipulation ability of a soft body array gripper to non-destructively grasp fragile objects with complex concave-convex undulating features and curvature features on the industrial production line. The specific technical solution is as follows:

[0004] A load-uniform active suction cup array based on a bistable structure, comprising: an elastic base, a bistable structure, an active suction cup, and a layer-blocking variable stiffness structure. The bistable structures are fixedly arranged in an array form on the front surface of the elastic base, and an active suction cup is installed and connected to each bistable structure. The layer-blocking variable stiffness structure is arranged in a vertical and horizontal arrangement on the back surface of the elastic base.

[0005] Further, the elastic base is made of silicone rubber elastic material. The front of the elastic base is provided with fixed slots arranged in an array, and the back is provided with ramp-shaped stress relief slots arranged vertically and horizontally; the peripheral sides of the elastic base are also provided with ear protection structures, and fixing holes are provided on the ear protection structures.

[0006] Further, the bistable structure includes: an H-shaped rigid frame, a reset driving airbag, a fixed boss, and a planar bearing beam; the H-shaped rigid frame is composed of two vertical brackets on both sides and a horizontal bracket in the middle. A through-hole structure is provided in the middle part of the horizontal bracket. The through-hole structure is a three-way port. Its upper and lower ports are located on the upper and lower surfaces of the horizontal bracket. One reset driving airbag is connected to each of the upper and lower side ports. The side port is located on the front side of the horizontal bracket, and an air pipe interface is installed at the middle side port; the fixed boss is arranged on the upper and lower sides of the H-shaped rigid frame and is connected to the vertical brackets on both sides of the H-shaped rigid frame through the planar bearing beam; one end of the reset driving airbag abuts against the horizontal bracket, and the other end abuts against the fixed boss; the planar bearing beam is composed of a rigid bearing beam section in the middle section and elastic bearing beam sections at both ends. The elastic bearing beam sections at both ends are respectively connected to the side parts of the fixed boss and the inner sides of the vertical brackets. The rigid bearing beam section is made of a hard material, and the elastic bearing beam section is made of an elastic material.

[0007] Further, the fixed boss on the lower side of the H-shaped rigid frame is embedded and fixed in the fixed slot, and an active suction cup is installed on the fixed boss on the upper side.

[0008] Further, the layer-blocking variable stiffness structure specifically includes: a transverse long-layer-blocking variable stiffness structure and a longitudinal short-layer-blocking variable stiffness structure. The number of the transverse long-layer-blocking variable stiffness structures is the same as the number of rows of bumps formed by the ramp-shaped stress relief slots on the back of the elastic base, and the number of the longitudinal short-layer-blocking variable stiffness structures is the same as the number of columns of the bumps. The transverse long-layer-blocking variable stiffness structures and the longitudinal short-layer-blocking variable stiffness structures are arranged in a staggered manner corresponding to each row and each column on the back of the elastic base.

[0009] Further, the transverse long-layer-blocking variable stiffness structure and the longitudinal short-layer-blocking variable stiffness structure are composed of a soft elastic outer shell and layered internal friction plates encapsulated therein.

[0010] Further, the active suction cup includes a suction cup main body. The suction cup main body is made of silicone rubber elastic material. The suction cup mouth at its upper end is trumpet-shaped to form an adsorption cavity; a central air passage is provided inside it and is communicated with the adsorption cavity; an external air pipe interface is provided on the side surface at its lower end and is communicated with the central air passage.

[0011] Advantages of the present invention:

[0012] The present invention provides a suction cup array that can conformally deform according to the complex uneven features and curvature characteristics of the target object's surface. The suction cups can actively adhere to the surface of the target object, and the shape of the suction cup array after conformal deformation is maintained through a layer-blocking variable stiffness structure, thereby achieving uniform load distribution and enhancing the ability to non-destructively adsorb, grasp and manipulate the target object. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the overall structure of a load-distributed active suction cup array based on a bistable structure according to an embodiment of the present invention;

[0014] Figure 2 1 is a schematic structural diagram of a conformably deformable elastic base according to an embodiment of the present invention;

[0015] Figure 3 is a schematic diagram of the specific structure of a single bistable structure according to an embodiment of the present invention;

[0016] Figure 4 It is a schematic diagram of the coordinate curves of the deformation displacement-elastic reaction force change characteristics, the deformation displacement-elastic potential energy change characteristics and the energy barrier characteristics between the two stable states during the deformation process of the bistable structure;

[0017] Figure 5 yes Figure 4 Schematic diagram of the structural state change process of the bistable structure shown in the middle coordinate curve at different key points in the curve after the deformation is triggered;

[0018] Figure 6 2 is a schematic structural diagram of an active suction cup according to an embodiment of the present invention;

[0019] Figure 7 is a schematic diagram of a layer-blocking variable stiffness structure and its specific arrangement according to an embodiment of the present invention;

[0020] Figure 8(a) is a schematic diagram of the internal stress mechanical model of the layer-blocking variable-stiffness structure after it is clamped under negative pressure driving;

[0021] Figure 8(b) is a schematic diagram of the mechanical characteristics of the layer-blocking variable stiffness structure in two different states: the clamped state and the default state;

[0022] Figure 9(a) Schematic diagram of the deformation effect of the elastic base when adsorbing and grasping the surface of a positive curvature sphere;

[0023] Figure 9 (b) is a schematic diagram of the deformation effect of the elastic base when it is adsorbed and grasped on the surface of the negative curvature saddle surface;

[0024] FIG10( a ) is a schematic diagram showing the load distribution effect of the active suction cup array when adsorbing a target object on a surface with complex undulating concave-convex features;

[0025] Figure 10(b) shows the load distribution effect when the active suction cup array adsorbs the target object on the surface with a curvature feature;

[0026] In the figure, 100 - elastic base, 200 - bistable structure, 300 - active suction cup, 400 - transverse long - type layer - blocking variable stiffness structure, 500 - longitudinal short - type layer - blocking variable stiffness structure, 101 - fixed slot, 102 - ramp - shaped stress - release slot, 103 - ear protection structure, 104 - fixing hole, 201 - H - shaped rigid frame, 202 - elastic bearing beam segment, 203 - rigid bearing beam segment, 204 - fixing boss, 205 - reset driving airbag, 206 - trachea interface, 301 - suction cup body, 302 - adsorption cavity, 303 - central air duct, 304 - external trachea interface, 501 - soft elastic outer shell, 502 - friction plate. Specific implementation mode

[0027] In order to make the objectives, technical solutions and technical effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the specification drawings and embodiments.

[0028] In the embodiment, the present invention proposes a suction cup array, which combines an elastically deformable elastic base 100, a sheet - type bearing beam - type bistable structure 200 that can automatically reset, and a layer - blocking variable stiffness structure. The surface of the target object can be conformally adsorbed and grabbed without damage through the longitudinal conformable deformation of the bistable structure 200 and the radial conformable deformation of the elastic base 100, and the shape - maintaining function after deformation is realized through the elastic potential energy barrier characteristic of the bistable structure 200 and the blocking characteristic of the layer - blocking variable stiffness structure.

[0029] Specifically, as Figure 1 shown, the load - distributing active suction cup array based on the bistable structure includes: an elastic base 100, a bistable structure 200, an active suction cup 300, and a layer - blocking variable stiffness structure. The bistable structures 200 are fixedly arranged in an array form on the front surface of the elastic base 100, and an active suction cup 300 is installed and connected to each bistable structure 200. The layer - blocking variable stiffness structure is arranged in a vertical and horizontal arrangement on the back surface of the elastic base 100.

[0030] As Figure 2As shown, the elastic base 100 is made of silicone rubber elastic material. The front surface of the elastic base 100 is provided with fixing slots 101 arranged in an array, and the back surface is provided with slope-shaped stress relief slots 102 arranged vertically and horizontally. When the elastic base is subjected to a force, the elastic material near the slope-shaped stress relief slots 102 on the back surface bends and compresses, enabling the elastic base 100 to conformably deform to surfaces with different curvatures, enhancing the adhesion, bearing capacity, and stability of the active suction cup array for adsorption and grasping. The peripheral sides of the elastic base 100 are also provided with ear protection structures 103 for fixing. Fixing holes 104 are provided on the ear protection structures 103, enabling the elastic base 100 to be connected to the end of the manipulator through a hook, ball joint link, or other means.

[0031] As Figure 3 shown, the bistable structure 200 includes: an H-shaped rigid frame 201, a reset driving airbag 205, fixing bosses 204, and a planar bearing beam. The H-shaped rigid frame 201 is composed of two vertical brackets on both sides and a middle horizontal bracket. A through-hole structure is provided in the middle part of the horizontal bracket. The through-hole structure is a three-way port, with its upper and lower ports located on the upper and lower surfaces of the horizontal bracket. One reset driving airbag 205 is connected to each of the upper and lower side ports. The side port is located on the front surface of the horizontal bracket, and an air pipe interface 206 is installed at the middle side port. The fixing bosses 204 are provided on the upper and lower sides of the H-shaped rigid frame 201 and are connected to the vertical brackets on both sides of the H-shaped rigid frame 201 through the planar bearing beam. One end of the reset driving airbag 205 abuts against the horizontal bracket, and the other end abuts against the fixing boss 204. The planar bearing beam is a double-sheet buckling elastic beam, specifically composed of a rigid bearing beam section 203 in the middle section and elastic bearing beam sections 202 at both ends. The elastic bearing beam sections 202 at both ends are respectively connected to the side parts of the fixing bosses 204 and the inner sides of the vertical brackets. The rigid bearing beam section 203 is made of a hard material, and the elastic bearing beam sections 202 are made of an elastic material. Among them, the fixing boss 204 on the lower side of the H-shaped rigid frame 201 is embedded and fixed in the fixing slot 101, and the active suction cup 300 is installed on the fixing boss 204 on the upper side.

[0032] As Figure 4 and Figure 5As shown, the normal working range of the bistable structure 200 is located in the CG segment of the graph line. When deformation occurs outside the normal working range: in the AC segment and the GI segment, both the elastic reaction force and the internal potential energy increase sharply to prevent further deformation. Within the normal working range, when the bistable structure 200 is triggered by an external force to deform, its elastic reaction force experiences a process of first increasing (point D), then decreasing to zero (point E), then increasing in the reverse direction (point F), and then decreasing to zero again (point G), while the elastic potential energy experiences a process of first increasing to a maximum value (point E) and then decreasing to zero (point G); among them, the position where the elastic reaction force is zero and the elastic potential energy is the largest (point E) is the mechanical dead point position of the bistable structure 200, and the elastic potential energy inside the bistable structure 200 corresponding to the mechanical dead point position is the elastic potential energy barrier characteristic of the bistable structure 200. Therefore, when the bistable structure 200 is triggered, the elastic bearing beam segment 202 of its planar bearing beam deforms, causing the bearing beam to swing from the high-potential stable state to the low-potential stable state and remain at the low-potential stable state position, realizing the function of maintaining the deformed shape; only under the drive of the reset drive airbag 205, that is, when the reset drive airbag 205 pops out, can the bistable structure 200 actively reset to the high-potential stable state position to place the target object. This design avoids the problems of limited bearing capacity and limited adsorption and grasping stability caused by the spring return elastic force in the existing spring suspension scheme. In the design of the bistable structure 200, its deformation trigger threshold and elastic potential energy barrier are numerically equal, and are related to the design parameters such as the span w of its bearing beam, the length l of the rigid bearing beam segment 203, the length t of the elastic bearing beam segment 202 e , the thickness t of the bearing beam, the swing angle α of the bearing beam, and the overall width d of the bistable structure 200; among them, the span w and the length t e are negatively correlated with the trigger threshold; the thickness t, the swing angle α, the length l, and the overall width d are positively correlated with the trigger threshold. The specific correlation coefficients and correlation function forms mainly depend on the physical properties of the actual manufacturing materials used. In addition, factors such as temperature, humidity, and material fatigue degree all affect the correlation coefficients and correlation function forms.

[0033] As Figure 6 shown, the active suction cup 300 includes a suction cup main body 301, the suction cup main body 301 is made of an organosilicon rubber elastic material, the suction cup mouth at its upper end is trumpet-shaped, forming a suction cavity 302; a hollow air passage 303 is provided inside it and communicates with the suction cavity 302; an external air pipe interface 304 is opened on the side surface at its lower end and communicates with the hollow air passage 303, and the adsorption and grasping of the target object can be realized by connecting a negative pressure drive source at the external air pipe interface 304.

[0034] As Figure 7As shown, the layer-blocking variable stiffness structure adopts a design in which a soft elastic outer shell 501 encloses laminated internal friction plates 502. When driven by negative pressure, under the extrusion of the soft elastic outer shell 501, the friction plates 502 inside the layer-blocking variable stiffness structure will hold each other tightly. In the embodiment of the present invention, the layer-blocking variable stiffness structure specifically includes: a transverse long-layer-blocking variable stiffness structure 400 and a longitudinal short-layer-blocking variable stiffness structure 500. The number of the transverse long-layer-blocking variable stiffness structures 400 is the same as the number of rows of bumps formed by stress relief grooves on the back of the elastic base 100, and the number of the longitudinal short-layer-blocking variable stiffness structures 500 is the same as the number of columns of the bumps. The transverse long-layer-blocking variable stiffness structures 400 and the longitudinal short-layer-blocking variable stiffness structures 500 are arranged in a staggered manner corresponding to each row and each column on the back of the elastic base 100.

[0035] As shown in the simplified mechanical model and mechanical property curve diagrams in FIGS. 8(a) and 8(b), it can be seen that within a certain load range, the layer-blocking variable stiffness structure can exhibit a higher stiffness than in the default state, so as to realize the shape retention of the deformable elastic base 100 after conformable deformation.

[0036] A load-uniform distributed active suction cup array based on a bistable structure of the present invention, as shown in FIGS. 9(a), 9(b), 10(a), and 10(b), is a suction cup array that can undergo conformable deformation according to the complex concave-convex undulation characteristics and curvature characteristics of the surface of the target object. Among them, for the surface of the target object with complex undulation characteristics, the sheet-shaped load-bearing beam bistable structure 200 realizes the change in the height of the active suction cup 300 structure through the deformation between two stable states, so that each active suction cup 300 can be attached to the surface of the target object at different heights; for the target object with a curvature feature on the surface, the conformable deformable elastic base 100 can be attached to different surface curvatures under the action of its own material elasticity. The ramp-shaped stress relief grooves 102 designed on its back can effectively reduce the internal stress during the deformation of the elastic base 100 and increase the conformability of the deformation. This characteristic designed by the present invention can effectively avoid the problems of load concentration where only a certain part of the active suction cups are stressed and vacuum adsorption failure when the traditional rigid-frame active suction cup array adsorbs and grabs a target object with a curvature feature on the surface, realizing the load uniformity of the active suction cup array; at the same time, combined with the layer-blocking variable stiffness structure on the back, under the drive of negative pressure, its soft elastic outer shell structure 501 generates an inward extrusion trend, so that the sheet-shaped internal friction plates 502 inside the layer-blocking variable stiffness structure hold each other tightly, which can realize the shape retention of the suction cup array after deformation, improve the stability and bearing capacity of adsorption and grabbing, enhance the ability of non-destructive adsorption and grabbing and manipulation of the target object. When the negative pressure drive is removed, the layer-blocking variable stiffness structure returns to the default state. At this time, after releasing the target object, the elastic base 100 returns to its original shape.

[0037] To sum up, when the new active suction cup array of the present invention is working, the overall structure is connected to the end of the industrial robot or other execution end through the ear protection structure 103 of the conformably deformable elastic base 100 through a clamp, a ball head connecting rod or other mechanisms, and the external air pipe interface 304 on the side of the base of the active suction cup 300 and the air pipe interface 206 on the side end of the layer blocking variable stiffness structure are connected to the negative pressure gas drive source; the reset drive airbag 205 of the bistable structure 200 is connected to the positive pressure gas drive source through the air pipe interface 206. The specific steps for adsorption and grasping the target object are as follows: (1) the execution end moves close to and fits the surface of the target object, and the contact pressure of the fitting surface is used to trigger the conformal deformation of the sheet-like load-bearing beam bistable structure 200 and the elastic base 100 to achieve complete fitting, as shown in Figures 10 (a) and 10 (b); (2) the gas drive source provides negative pressure drive to enable the active suction cup 300 to fit and adsorb the surface of the target object; and under the action of the negative pressure drive, the layer blocking variable stiffness structure clamps the internal friction plate 502 to achieve stiffness change, thereby achieving the shape retention function of the elastic base 100 after conformal deformation; (3) when the target object is moved to a position and needs to be placed, the active suction cup 300 releases the target object due to the removal of the negative pressure drive, and the bistable structure 200 is reset under the action of the reset drive airbag 205, and the layer blocking variable stiffness structure after the removal of the negative pressure drive returns to the default state, and the elastic base 100 returns to the default shape under the action of the material elasticity, and the overall structure is reset.

[0038] Due to the application of the above-mentioned embodiments of the present invention, the advantages of the present invention compared with the existing active suction cup array adsorption grasping technology have been described in detail in the technical solution and will not be repeated here.

[0039] In the structural design description of the patent application of the present invention, the structural design illustrated by the embodiment of the active suction cup array based on the sheet-like load-bearing beam-type bistable structure and the conformable deformable elastic base is for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific number and orientation, and work in a specific assembly structure and operating sequence. Therefore, it cannot be understood as a limitation of the present invention.

[0040] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A load-uniform active suction cup array based on a bistable structure, characterized in that Comprising: An elastic base (100), a bistable structure (200), an active suction cup (300), and a layer-blocking variable stiffness structure. The bistable structures (200) are fixedly arranged in an array on the front surface of the elastic base (100), and an active suction cup (300) is mounted and connected to each bistable structure (200). The layer-blocking variable stiffness structure is arranged in a vertical and horizontal arrangement on the back surface of the elastic base (100).

2. The load-uniform active suction cup array based on a bistable structure according to claim 1, wherein The elastic base (100) is made of an organosilicon elastic material. Fixed slots (101) arranged in an array are provided on the front surface of the elastic base (100), and ramp-shaped stress relief slots (102) arranged vertically and horizontally are formed on the back surface. Ear protection structures (103) are further provided on the peripheral side surfaces of the elastic base (100), and fixing holes (104) are formed in the ear protection structures (103).

3. The load-uniform active suction cup array based on the bistable structure according to claim 2, wherein The bistable structure (200) includes: an H-shaped rigid frame (201), a reset driving airbag (205), a fixing boss (204), and a planar bearing beam. The H-shaped rigid frame (201) is composed of two vertical brackets on both sides and a horizontal bracket in the middle. A through-hole structure is provided in the middle part of the horizontal bracket. The through-hole structure is a three-way port, and its upper and lower ports are located on the upper and lower surfaces of the horizontal bracket. A reset driving airbag (205) is connected to each of the upper and lower side ports. The middle side port is located on the front side surface of the horizontal bracket, and an air pipe interface (206) is installed at the middle side port. The fixing boss (204) is provided on the upper and lower sides of the H-shaped rigid frame (201) and is connected to the vertical brackets on both sides of the H-shaped rigid frame (201) through the planar bearing beam. One end of the reset driving airbag (205) abuts against the horizontal bracket, and the other end abuts against the fixing boss (204). The planar bearing beam is composed of a rigid bearing beam section (203) in the middle section and elastic bearing beam sections (202) at both ends. The elastic bearing beam sections (202) at both ends are respectively connected to the side part of the fixing boss (204) and the inner side of the vertical bracket. The rigid bearing beam section (203) is made of a hard material, and the elastic bearing beam sections (202) are made of an elastic material.

4. The load-uniform active sucker array based on the bistable structure according to claim 3, wherein The fixing boss (204) on the lower side of the H-shaped rigid frame (201) is embedded and fixed in the fixed slot (101), and the active suction cup (300) is mounted on the fixing boss (204) on the upper side.

5. The load-uniform distributed active sucker array based on a bistable structure according to claim 2, characterized in that, The layer-blocking variable stiffness structure specifically includes: a transverse long-layer-blocking variable stiffness structure (400) and a longitudinal short-layer-blocking variable stiffness structure (500). The number of the transverse long-layer-blocking variable stiffness structures (400) is the same as the number of rows of bumps formed by separating the ramp-shaped stress relief slots (102) on the back surface of the elastic base (100), and the number of the longitudinal short-layer-blocking variable stiffness structures (500) is the same as the number of columns of the bumps. The transverse long-layer-blocking variable stiffness structures (400) and the longitudinal short-layer-blocking variable stiffness structures (500) are arranged in a staggered manner corresponding to each row and each column on the back surface of the elastic base (100).

6. The active sucker array with uniform load distribution based on a bistable structure according to claim 5, characterized in that The horizontal long-layer blocking variable stiffness structure (400) and the vertical short-layer blocking variable stiffness structure (500) are composed of a soft elastic outer shell (501) and layered internal friction plates (502) enclosed within the soft elastic outer shell (501).

7. The load-uniform active sucker array based on a bistable structure according to claim 1, wherein The active suction cup (300) includes a suction cup main body (301), which is made of an organosilicon rubber elastic material. The suction cup opening at the upper end of the suction cup main body (301) is trumpet-shaped, forming a suction cavity (302); a central air passage (303) is provided inside the suction cup main body (301) and is communicated with the suction cavity (302); an external trachea interface (304) is provided on the side surface of the lower end of the suction cup main body (301) and is communicated with the central air passage (303).

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