A pneumatic bistable soft robotic gripper for fruits and vegetables

Abstract

The present invention relates to an agricultural picking machine, and the purpose is to provide a pneumatic bistable fruit and vegetable grasping soft manipulator, which can quickly grasp fruits and vegetables with different sizes so as to improve the application range and grasping efficiency of the soft manipulator. The technical solution is a pneumatic bistable fruit and vegetable grasping soft manipulator, which is characterized in that the soft manipulator comprises a plurality of soft fingers communicating with an air source, an airbag communicating with the air source, and a plurality of connecting mechanisms for respectively mounting the plurality of soft fingers under the airbag.

Description

Technical Field

[0001] The present invention relates to an agricultural picking machine, specifically a pneumatic bistable fruit and vegetable grasping soft manipulator. Background Art

[0002] China is not only the largest fruit and vegetable planting country in the world, but also the largest fruit and vegetable consuming country. With the continuous development of the economy, the production and marketing mode of fruits and vegetables in China is changing from self-sale in the production area to retail in different places, and the integrated fruit and vegetable industrial chain of picking, sorting and packaging, transportation and distribution is being gradually improved. In recent years, with the rapid development of agricultural mechanization, in the links of fruit and vegetable picking, sorting and processing, various mechanized and automated equipment are replacing manual labor. However, these devices usually use rigid manipulators, which are easy to damage fruits and vegetables and increase the damage rate of fruits and vegetables.

[0003] In recent years, pneumatic soft manipulators made of soft materials have developed rapidly, providing a new method for non-destructive grasping of fruits and vegetables. However, the grasping scale of most pneumatic soft manipulators is fixed, and the adaptability of grasping is low when the size of fruits and vegetables changes, resulting in limited types of fruits and vegetables that can be grasped. Therefore, it is of great significance to design a fruit and vegetable grasping soft manipulator to improve the adaptability of the soft manipulator. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies of the above background art and provide a pneumatic bistable fruit and vegetable grasping soft manipulator, which can quickly grasp fruits and vegetables of different sizes to improve the application range and grasping efficiency of the soft manipulator.

[0005] The technical solution provided by the present invention is as follows:

[0006] A pneumatic bistable fruit and vegetable grasping soft manipulator, characterized in that the soft manipulator includes a plurality of soft fingers communicating with a gas source, an airbag communicating with the gas source, and a plurality of connecting mechanisms for respectively mounting the plurality of soft fingers under the airbag;

[0007] The airbag includes an upper end cover and a lower end cover supported by a middle pillar and arranged coaxially, a film surrounding the circumferential direction and covering the sides of the upper end cover, the lower end cover and the middle pillar to form a sealed cavity, and a plurality of bistable mechanisms arranged in an array along the circumferential direction of the upper and lower end covers in the sealed cavity and connecting the upper end cover and the lower end cover;

[0008] The connecting mechanism includes a connecting plate rotatably hinged to the bottom end of the lower end cover, a paste block pasted on the outer surface of the film, a side bracket hinged to the sides of the paste block and the connecting plate at both ends, and a finger mounting block fixed on the connecting plate and mounting the soft finger.

[0009] The middle pillar includes a plurality of flat plates radially arranged around the airbag axis in the closed cavity with the plate surfaces parallel to the airbag axis. The upper and lower end faces of each flat plate are respectively sealed and connected to the upper end cover and the lower end cover, thereby dividing the closed cavity into a plurality of fan-shaped spaces; the outer side surface of the flat plate is flush with the edges of the upper and lower end covers while the other side surface is spaced from the adjacent flat plates, so that the gas in each fan-shaped space can flow.

[0010] The plurality of bistable mechanisms are arranged one by one in the plurality of fan-shaped spaces; each bistable mechanism includes four identical flexible beams and a rigid block located in the fan-shaped space. Among them, the upper end cover and the lower end cover are respectively connected to one ends of two flexible beams arranged parallel to the diameter direction of the upper and lower end covers, and the upper and lower sides of the rigid block are respectively connected to the other ends of the two flexible beams; the total length of the rigid block plus the flexible beams connected to its upper and lower sides is greater than the distance between the upper and lower end covers to obtain two stable states.

[0011] The soft finger includes a bottom plate formed by sequentially bonding a finger upper bottom layer, a limiting layer, and a finger lower bottom layer, and a finger main body connected to the bottom plate; the finger main body is composed of a plurality of cube chambers protruding in the direction away from the bottom plate arranged linearly at equal intervals. Each chamber is interconnected by a channel at the bottom and is conducted to the external air source through an air inlet pipe communicating with the chambers, so as to inflate and deflate the soft finger.

[0012] An air pipe communicating with the closed cavity is installed on the upper end cover, and this air pipe is communicated with the external air source to inflate and deflate the airbag.

[0013] Both the finger upper bottom layer and the finger lower bottom layer are made of silica gel material, and the limiting layer is made of nylon cloth material.

[0014] The finger mounting block and the connecting plate are provided with through holes facilitating the insertion of the air inlet pipe.

[0015] The film is a silica gel film.

[0016] The connecting plate is hinged to the bottom bracket, and the bottom bracket is fixed to the bottom edge of the airbag by bolts.

[0017] The rigid block and the paste block are respectively bonded and fixed on the two corresponding sides of the silica gel film.

[0018] The beneficial effects of the present invention are as follows:

[0019] Both the airbag and the soft finger of the present invention are pneumatically driven. The unification of the driving methods simplifies the complexity of driving control; while maintaining the flexibility of the soft finger, the present invention expands the grasping scale of the soft finger through the bistable mechanism. At the same time, the bistable mechanism effectively reduces the driving response time of the airbag, improves the adaptability of the soft finger, and thus increases the types of fruits and vegetables that can be grasped. Brief Description of the Drawings

[0020] Figure 1 is the front view structural schematic diagram of an embodiment of the present invention.

[0021] Figure 2 is the three-dimensional structural schematic diagram of an embodiment of the present invention.

[0022] Figure 3 is the front view structural schematic diagram of the airbag in an embodiment of the present invention (the silicone film in the figure is hidden to show the internal structure).

[0023] Figure 4 is the three-dimensional structural schematic diagram of the airbag in an embodiment of the present invention.

[0024] Figure 5 is the three-dimensional structural schematic diagram of the airbag in an embodiment of the present invention (the silicone film is hidden).

[0025] Figure 6 is the three-dimensional structural schematic diagram of the bottom bracket in an embodiment of the present invention.

[0026] Figure 7 is the front view structural schematic diagram of the upper end cap in an embodiment of the present invention.

[0027] Figure 8 is the three-dimensional structural schematic diagram of the connecting plate in an embodiment of the present invention.

[0028] Figure 9 is the front view structural schematic diagram (cross-sectional view) of the soft finger in an embodiment of the present invention.

[0029] Figure 10 is the three-dimensional structural schematic diagram (cross-sectional view) of the soft finger in an embodiment of the present invention.

[0030] Figure 11 is the schematic diagram of the working state when only the soft finger is inflated and pressurized to bend for fruit and vegetable clamping operation in an embodiment of the present invention.

[0031] Figure 12 is the schematic diagram of the state when only the airbag is inflated and pressurized in an embodiment of the present invention (the silicone film in the figure is hidden).

[0032] Figure 13 is the schematic diagram of the working state when the airbag and the soft finger are simultaneously inflated and pressurized to perform fruit and vegetable grasping operation in an embodiment of the present invention.

[0033] Reference numerals in the figure: airbag 1, air tube 1-1, upper end cover 1-2, rigid block 1-3, flexible beam 1-4, silica gel film 1-5, lower end cover 1-6, middle pillar 1-7, outer side surface 1-71, soft finger 2, air inlet tube 2-1, finger main body 2-2, upper bottom layer of finger 2-3, limiting layer 2-4, lower bottom layer of finger 2-5, side bracket 3, connecting plate 4, finger mounting block 5, bottom bracket 6, sticking block 7, fruit and vegetable 8, gap 9. Detailed implementation manners

[0034] The following is further described in conjunction with the embodiments shown in the accompanying drawings.

[0035] Figure 1 and Figure 2 The pneumatic bistable fruit and vegetable grasping soft manipulator shown in the embodiment includes an airbag 1, soft fingers 2 (preferably 3), a side bracket 3, a connecting plate 4 (as Figure 8 shown), a finger mounting block 5, a bottom bracket 6 (as Figure 6 shown), a sticking block 7, and corresponding bolts, pins, etc.

[0036] Figure 3 、 Figure 4 and Figure 5 The airbag 1 shown in and is of a closed structure and is only connected to an external air source (the external air source is preferably an air pump) through the air tube 1-1, and includes the air tube 1-1, the upper end cover 1-2, the rigid block 1-3, the flexible beam 1-4, the silica gel film 1-5, the lower end cover 1-6, and three middle pillars 1-7 with the same structure. The picking robot is usually connected to the upper end cover, so that it can carry the pneumatic bistable fruit and vegetable grasping soft manipulator to the picking site for operation.

[0037] The upper end cover 1-2 and the lower end cover 1-6 are both circular plates with the same diameter. They are parallel to each other and arranged coaxially. The air pipe 1-1 is fixed in the through hole of the upper end cover. Three intermediate struts 1-7 (preferably rectangular flat plates) are located between the upper end cover and the lower end cover and are radially arranged along the axis of the upper end cover and the lower end cover (the adjacent intermediate struts form a 120-degree angle), thus dividing the space between the upper end cover and the lower end cover into three fan-shaped spaces. The upper and lower ends of each intermediate strut are respectively fixed to the upper end cover and the lower end cover, and the outer side surface 1-71 is flush with the edges of the upper end cover and the lower end cover. The other side surface keeps a gap 9 from the adjacent intermediate strut (the length between the two side surfaces of the intermediate strut is less than the radius of the upper and lower end covers) so that the air flow inside the airbag can circulate with each other (in this way, the pressure received by each bistable mechanism is the same and can generate movement simultaneously). The silica gel film 1-5 wraps around the circumferential direction and covers the outer side surfaces of the upper end cover, the lower end cover and each intermediate strut, and is connected and fixed (preferably pasted) to the outer circumferential surface of the upper end cover, the outer circumferential surface of the lower end cover and the outer side surfaces of the intermediate struts, thus completely covering the three fan-shaped cavities formed by the upper end cover, the lower end cover and the intermediate struts. The rigid block 1-3 is bonded to the inner surface of the silica gel film. One bistable mechanism is arranged in each fan-shaped cavity, and this bistable mechanism is located at the central part of the fan-shaped cavity and close to the circumferential edge of the upper and lower end covers. In addition, each bistable mechanism is equipped with four flexible beams 1-4 with the same structure. The upper end cover and the lower end cover are respectively connected to one end of two flexible beams (grooves for inserting and bonding the flexible beams are respectively opened on the upper end cover and the lower end cover, see Figure 7 ; the connection method between the rigid block and the flexible beam is also adopted in this way). The other ends of the two flexible beams are connected to the rigid block 1-3 (the two flexible beams connected to the upper end cover at one end are both connected to the upper end of the rigid block; the two flexible beams connected to the lower end cover at one end are both connected to the lower end of the rigid block). The two flexible beams are also arranged in parallel and are set along the diameter direction of the upper end cover and the lower end cover (see Figure 3 ). In addition, the total length of the two flexible beams (the flexible beams respectively connected to the upper side and the lower side of the rigid block) plus the rigid block needs to be greater than the distance between the upper and lower end covers, so that the bistable mechanism formed by the two flexible beams and the rigid block has two stable states ( Figure 3 shows a stable state when the rigid block retracts into the airbag, and the other stable state can be seen in Figure 12 ). The material of the flexible beam is preferably thin steel sheet (preferably spring steel) to facilitate the large deformation of the flexible beam. Obviously, the rigid block is at the position where the deformation of the silica gel film is the largest. When the airbag is inflated, the air pressure drives the silica gel film to expand and deform, that is, it bulges out radially in the closed cavity, thus driving the bistable mechanism to quickly jump to another stable state. On the contrary, when the airbag exhausts air, the silica gel film contracts radially in the closed cavity.

[0038] Three soft fingers 2 are evenly distributed at the bottom end of the lower end cover along its axis so as to cooperate with each other to grasp fruits and vegetables 8; the bottom bracket 6 corresponding to each soft finger is fixed to the bottom edge of the airbag by bolts, and one end of the connecting plate 4 is hinged to the bottom bracket through a hinge shaft (the hinge shaft is perpendicular to the diameter of the lower end cover), so that the connecting plate can swing around the hinge shaft; one end of the side bracket 3 is hinged to the middle part of the connecting plate (the pin shaft position on the connecting plate is arranged at an interval distance from the hinge shaft) so as to apply force to swing the connecting plate, and the other end is hinged to the paste block 7; the paste block 7 is fixedly pasted on the outer surface of the silica gel film and the pasting position corresponds to the bistable mechanism rigid block 1-3 (the paste block and the rigid block are respectively bonded and fixed on the two corresponding sides of the silica gel film). The finger mounting block 5 is connected to the side of the connecting plate facing away from the pin shaft by bolts.

[0039] As Figure 9 As shown in FIGS. and

[0039] and FIG. 10, the soft finger 2 is a sealed structure (only communicated with the external air source through the air inlet pipe 2-1), and includes a finger main body 2-2, an upper bottom layer 2-3 and a lower bottom layer 2-5 of the finger, a limiting layer 2-4 and an air inlet pipe 2-1; the soft finger 2 is fixedly pasted on the finger mounting block 5.

[0040] The finger main body 2-2, the upper bottom layer 2-3 and the lower bottom layer 2-5 of the finger are all preferably made of silica gel material; the limiting layer 2-4 is preferably made of nylon cloth material; the upper bottom layer of the finger, the limiting layer and the lower bottom layer of the finger are bonded in sequence from top to bottom to form a bottom plate, and the finger main body 2-2 is hermetically bonded to the surface of one side of the bottom plate; the finger main body is composed of a plurality of protruding cubic chambers linearly arranged at equal intervals, and each chamber is interconnected by a channel at the bottom and communicated with the external air source (preferably an air pump) through the air inlet pipe 2-1 communicating with the chambers; usually, the air inlet pipe is arranged in the chamber at the end of the finger main body, and the outer wall of this chamber is directly installed on the finger mounting block. After the soft finger is installed, the bottom plates all face the axis direction of the lower end cover, while the finger main body faces away from the axial direction of the lower end cover.

[0041] The working mode of the present invention is as follows:

[0042] 1. Mode 1

[0043] (1) As Figure 1 and Figure 2 shown, the pneumatic bistable fruit and vegetable grasping soft manipulator is in an un-driven state, and the bistable mechanism is in the original stable state position;

[0044] (2) After the soft finger 2 is inflated by the external air source, the air pressure inside the soft finger increases. Due to the action of the restriction layer 2-4, the soft finger bends toward the axis of the lower end cover (the walls of each cubic chamber bulge outward, so that the two adjacent cubic chambers squeeze each other, causing the soft finger to bend toward the bottom plate). At this time, since the airbag is in an undriven state, the grasping scale of the soft finger is larger (as shown in FIG. 11 ), and it can grasp larger fruits and vegetables 8;

[0045] 2. Method 2

[0046] (1) After the airbag 1 is inflated by the external air source, the air pressure inside the airbag increases, and the silicone film 1-5 expands and deforms to move toward the outer diameter of the closed cavity, driving the bistable mechanism to quickly jump to another stable position, thereby driving the soft finger 2 to swing around the hinge axis of the connecting plate 4 and the bottom bracket 6; at this time, the soft finger is in an undriven state, such as Figure 12 As shown;

[0047] (2) The external air source inflates the soft finger 2, and the soft finger bends toward the axis of the lower end cap; compared with method 1, under the same air pressure, the soft finger can grasp smaller fruits and vegetables 8 (such as Figure 13 as shown).

[0048] In summary, when the airbag 1 is not driven, the grasping scale of the soft finger 2 is larger, which is suitable for grasping larger fruits and vegetables; when the airbag is driven, the grasping scale of the soft finger becomes smaller, which is suitable for grasping smaller fruits and vegetables. Therefore, while reducing its own driving response time, the airbag effectively expands the grasping scale of the soft finger and improves the adaptability of the soft finger to grasp fruits and vegetables.

[0049] Finally, it should be noted that the above examples are only specific embodiments of the present invention, but the present invention is not limited to the above embodiments and may have many variations. All variations that can be directly derived or associated with the contents disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A pneumatic bistable fruit and vegetable grasping soft manipulator, characterized in that: It includes several soft fingers connected to a gas source, an airbag connected to the gas source, and several connecting mechanisms for respectively installing the several soft fingers at the lower part of the airbag; The airbag includes an upper end cover (1-2) and a lower end cover (1-6) supported by an intermediate pillar (1-7), a film (1-5) that wraps around the circumferential direction of the upper end cover, the lower end cover, and the side of the intermediate pillar to form a sealed cavity, and several bistable mechanisms arranged in an array along the circumferential direction of the upper and lower end covers and connecting the upper end cover and the lower end cover in the sealed cavity; The connecting mechanism includes a connecting plate (4) rotatably hinged to the bottom end of the lower end cover, a paste block (7) pasted on the outer surface of the film, a side bracket (3) with both ends respectively hinged to the paste block and the connecting plate, and a finger mounting block (5) fixed on the connecting plate and mounting the soft finger; Each bistable mechanism includes four identical flexible beams (1-4) and a rigid block (1-3). One end of two parallel arranged flexible beams is respectively connected to the upper end cover and the lower end cover, and the upper and lower sides of the rigid block are respectively connected to the other ends of the two flexible beams; the total length of the rigid block plus the flexible beams connected to its upper and lower sides is greater than the distance between the upper and lower end covers, so as to obtain two stable states; The rigid block and the paste block are respectively bonded and fixed on two corresponding sides of the film.

2. The pneumatic bistable fruit and vegetable grasping soft manipulator according to claim 1, wherein: The intermediate pillar includes several flat plates radially arranged around the axis of the airbag in the sealed cavity and with the plate surfaces parallel to the axis of the airbag. The upper and lower end surfaces of each flat plate are respectively sealed and connected to the upper end cover and the lower end cover, so as to divide the sealed cavity into several fan-shaped spaces; one side of the flat plate is flush with the edge of the upper and lower end covers, while the other side is spaced from the adjacent flat plates, so that the gas in each fan-shaped space can circulate.

3. The pneumatic bistable fruit and vegetable grasping soft manipulator according to claim 2, characterized in that: The several bistable mechanisms are arranged one by one in the several fan-shaped spaces.

4. The pneumatic bistable fruit and vegetable grasping soft manipulator according to claim 3, characterized in that: The soft finger includes a bottom plate formed by sequentially bonding a finger upper bottom layer (2-3), a limiting layer (2-4), and a finger lower bottom layer (2-5), and a finger main body (2-2) connected to the bottom plate; the finger main body is composed of a plurality of cubic chambers protruding in the direction away from the bottom plate and linearly arranged at equal intervals. Each chamber is interconnected by a channel at the bottom and is connected to the external gas source through an air inlet pipe (2-1) communicating with the chamber, so as to inflate and deflate the soft finger.

5. The pneumatic bistable fruit and vegetable grasping soft manipulator according to claim 4, characterized in that: The upper end cover is provided with a trachea (1-1) communicating with the sealed cavity, and the trachea is connected to the external gas source to inflate and deflate the airbag.

6. The pneumatic bistable fruit and vegetable grasping soft manipulator according to claim 5, characterized in that: Both the finger upper bottom layer and the finger lower bottom layer are made of silica gel material, and the limiting layer is made of nylon cloth material.

7. The pneumatic bistable fruit and vegetable grasping soft manipulator according to claim 6, characterized in that: The finger mounting block and the connecting plate are provided with through holes facilitating the insertion of the trachea.

8. The pneumatic bistable fruit and vegetable grasping soft manipulator according to claim 7, characterized in that: The film is a silica gel film.

9. The pneumatic bistable fruit and vegetable grasping soft manipulator according to claim 8, wherein: The connecting plate is hinged to the bottom bracket, and the bottom bracket is fixed to the bottom edge of the airbag by bolts.

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