CN115648275A - Variable-rigidity hybrid bimodal two-finger soft gripper and gripping method thereof - Google Patents

Abstract

The invention discloses a variable-rigidity hybrid bimodal two-finger soft gripper and a gripping method thereof, belonging to the technical field of robot gripping and comprising a driving structure, a gripping structure, a rotating connection structure and a traction structure; the driving structure is rotationally connected with the grabbing structure through the rotational connecting structure, and the driving structure pulls the grabbing structure through the traction structure; the grabbing structure comprises two symmetrical claws, and each claw comprises a spring steel sheet, a plurality of heating sheets and a plurality of memory alloy sheets. The invention relates to a variable-rigidity two-finger soft hand, which has two grabbing modes of enveloping and clamping, can convert the grabbing modes in real time to adapt to the grabbing processes of different objects, can ensure the characteristics of holding force of a rigid body hand and flexibility of the soft hand, and can effectively avoid damaging or damaging the objects.

Description

A variable stiffness hybrid dual-mode two-finger soft gripper and its grasping method

technical field

The invention relates to the technical field of robot grasping, in particular to a variable stiffness mixed dual-mode two-finger soft gripper and a grasping method thereof.

Background technique

In the robot grasping operation, the traditional rigid manipulator achieves grasping through rigid contact, which is easy to cause the risk of damage to the manipulator itself and the work target. To achieve compliant operation, robots need to be equipped with expensive sensing devices and complex closed-loop control algorithms. Therefore, soft grippers made of flexible materials have appeared in recent years, and the overall structure of the fingers is soft and adaptable. At the same time, the contact stiffness is low, which has a natural protective effect on the object and is not easy to cause damage to the surface of the grasped object. However, softness can also lead to insufficient grip. Therefore, it is particularly important to develop various variable stiffness gripper mechanisms with the advantages of stiffness and soft feel. To this end, a variable stiffness hybrid dual-mode two-finger soft gripper and its grasping method are proposed.

Contents of the invention

The technical problem to be solved by the present invention is: how to solve the simplification of the traditional two-fingered hand grasping action without considering the specific grasping mode suitable for the object, and the rigid hand grasping is easy to cause damage or damage to the object, and the soft hand grasping force is insufficient. The problem is to provide a variable stiffness hybrid dual-modal two-finger soft gripper.

The present invention solves the above-mentioned technical problems through the following technical solutions. The present invention includes: a driving structure, a grasping structure, a rotating connection structure, and a traction structure; the driving structure and the grasping structure are rotationally connected through the rotating connection structure , the driving structure pulls the grasping structure through the traction structure;

The grasping structure includes two symmetrically arranged grippers, the grippers include a spring steel sheet, a plurality of heating sheets, and a plurality of memory alloy sheets, and the spring steel sheet is connected to the driving structure through the rotating connection structure Rotationally connected, a plurality of the heating sheets are arranged at intervals on the outer surface of the spring steel sheet, and a plurality of the memory alloy sheets are arranged at intervals on the inner surface of the spring steel sheet.

Further, the top bracket of the driving structure, the top cover plate, and the digital steering gear, the top cover plate is arranged on the upper end of the top bracket, and the digital steering gear is arranged inside the top bracket.

Furthermore, a connection block is provided on the outer surface of the digital steering gear, and a mounting seat is provided inside the top bracket, and the connection block is detachably connected to the mounting seat.

Furthermore, the outer sheath of the gripper is provided with a silicone sheath matching its shape.

Furthermore, the inner surface of the silicone sleeve is provided with a plurality of anti-slip strips.

Furthermore, the rotating connection structure includes a first fixed seat, a second fixed seat, a torsion spring, and a cylindrical pin, the second fixed seat is arranged on the top of the spring steel sheet, and the first fixed seat is arranged on the top of the spring steel sheet. The lower end of the top bracket, the second fixed seat and the first fixed seat are rotationally connected through cylindrical pins and torsion springs.

Furthermore, the traction structure includes a traction rope and a plurality of connection seats, and the plurality of connection seats are arranged at intervals on the inner surface of the spring steel sheet and interlaced with the memory alloy sheet, and one end of the traction rope It is connected with the digital steering gear, and the other end passes through the top bracket, the second fixing seat and each connecting seat in sequence and is fixedly connected with the connecting seat at the end.

The present invention also provides a grasping method of a variable stiffness mixed dual-mode two-finger soft gripper, using the above-mentioned variable stiffness mixed dual-mode two-finger soft gripper to grab objects, including the following steps:

S1: Judging according to the properties of the contact surface between the two-finger soft gripper and the object, select the envelope grabbing mode or the gripping mode to grab;

S2: When the envelope grabbing mode is selected, the spring steel sheet is driven to bend from the bottom to the top through the traction rope under the rotation of the digital steering gear, and the bending deformation fits the outer surface of the object as much as possible. So as to achieve the enveloping state; when the clamping mode is selected, the temperature of the heating sheet increases through the DC power supply, and the memory alloy sheet on the inner surface of the spring steel sheet becomes curved in a C shape as the temperature rises. Under the restriction, the inner side of the claws is flat and non-concave, and finally the two claws are pulled closer to the center of the object by pulling the traction rope, forming a gripping mode.

Furthermore, when the contact surface between the two-finger soft gripper and the object has a radian change, such as apples, table tennis balls, teddy bear dolls, etc., the object is grasped by the envelope grasping mode; when the two-finger The contact surface between the soft gripper and the object does not change in curvature. For example, square objects such as Rubik's Cube and flat objects are grasped by the gripping mode. The above classification of grasping modes is based on a large amount of data for deep reinforcement learning. The obtained regularity is carried out to summarize the results.

The present invention is a variable stiffness two-finger soft hand, which has two grasping modes of enveloping and clamping, and can switch grasping modes in real time to adapt to the grasping process of different objects. The designed variable stiffness two-finger soft hand The hand can guarantee both the gripping force of a rigid hand and the flexibility of a soft hand, which can effectively avoid damage or damage to objects.

Description of drawings

Fig. 1 is an exploded schematic diagram of a variable-stiffness hybrid dual-mode two-finger soft gripper in an embodiment of the present invention;

Fig. 2 is a schematic diagram of the overall structure of the variable stiffness hybrid dual-mode two-finger soft gripper in the embodiment of the present invention;

Fig. 3 is a schematic diagram of the clamping and grasping mode of the variable stiffness hybrid dual-mode two-finger soft gripper in the embodiment of the present invention;

Fig. 4 is a schematic diagram of the envelope grasping mode of the variable stiffness hybrid dual-mode two-finger soft gripper in the embodiment of the present invention.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

As shown in Figures 1 and 2, this embodiment provides a technical solution: a variable stiffness hybrid dual-mode two-finger soft gripper, including a driving structure and a grasping structure;

The drive structure includes a top bracket 11, a top cover plate 12, and a digital steering gear 13. The top cover plate 12 is arranged on the upper end of the top bracket 11 and is detachably connected thereto. The digital steering gear 13 is installed on the The inside of the top support 11 is detachably connected thereto. Among them, the top cover 12 is connected to the end of the UR5 robotic arm, and the digital steering gear 13 is controlled by an Arduino board containing hardware and software (Arduino IDE).

The outer surface of the digital steering gear 13 is provided with a connecting block 131, and the inside of the top bracket 11 is provided with a mounting seat 111, and the connecting block 131 and the mounting seat 111 are detachably connected by connecting bolts, thereby realizing digital steering gear 131. The detachable connection between the steering gear 13 and the top bracket 11.

The grasping structure includes two claws symmetrically arranged at the lower end of the top bracket 11 , both claws are rotatably connected with the top bracket 11 , and the grasping action is realized under the control of the digital steering gear 13 .

The claws include a spring steel sheet 21 (elastic metal sheet), a plurality of heating sheets 22, and a plurality of memory alloy sheets 23, the upper end of the spring steel sheet 21 is rotationally connected with the lower end of the top bracket 11, and the plurality of the The heating plates 22 are arranged at intervals on the outer surface of the spring steel sheet 21 and are fixedly connected thereto, and a plurality of the memory alloy sheets 23 are arranged at intervals on the inner surface of the spring steel sheet 21 and are fixedly connected thereto.

In this embodiment, there are two heating sheets 22 on a single paw, and the two heating sheets 22 are arranged longitudinally on the outer surface of the spring steel sheet 21 at intervals. Through the longitudinally distributed heating sheets 22 , the memory alloy sheet 23 can be better uniformly heated through the heat conduction of the spring steel sheet 21 . The heating sheet 22 is controlled to be turned on and off by a direct current source.

In this embodiment, the number of memory alloy sheets 23 on a single grip is three, and the three memory alloy sheets 23 are arranged on the inner surface of the spring steel sheet 21 at intervals along the lateral direction. The installation position of the memory alloy sheet 23 is designed in imitation of people's finger joint positions.

In this embodiment, the spring steel sheet 21 is spade-shaped.

In this embodiment, the outer sleeve of the gripper is provided with a silicone sleeve 24 matching its shape, and a plurality of anti-slip strips 241 are provided on the lower end of the inner surface of the silicone sleeve 24, and the silicone sleeve 24 is used in conjunction with the anti-slip strips 241. , Play a good anti-slip effect when grabbing objects.

In this embodiment, the variable-stiffness hybrid dual-mode two-finger soft gripper also includes a rotating connection structure, and the rotating connection structure includes a first fixing seat 43, a second fixing seat 41, a torsion spring, and a cylindrical pin 42, The second fixing seat 41 is arranged on the top of the spring steel sheet 21 and is detachably connected thereto. The first fixing seat 43 is arranged at the lower end of the top bracket 11 and integrally formed therewith. The second fixing seat 41 It is rotationally connected with the first fixing seat 43 through a torsion spring and a cylindrical pin 42 , and the torsion spring is sleeved on the cylindrical pin 42 .

The variable stiffness hybrid dual-mode two-finger soft gripper also includes a traction structure, the traction structure includes a traction rope 31, a plurality of connecting seats 32, and a plurality of connecting seats 32 are arranged at intervals on the inner surface of the spring steel sheet 21 And it is detachably connected with it, and interlaced with the memory alloy sheet 23, one end of the traction rope 31 is connected with the digital steering gear 13, driven by the digital steering gear 13, and the other end passes through the top bracket 11, The second fixing base 41 and each connecting base 32 are fixedly connected with the connecting base located at the end. A plurality of connection seats 32 are arranged on the inner surface of the spring steel sheet 21, and the traction rope is connected and fixed at the end of the spring steel sheet 21 in sequence. , able to control the bending action of the claw.

In this embodiment, the number of the connecting seats 32 on a single gripper is three.

It should be noted that, after testing, it has been shown that the memory alloy sheet 23 carried by the variable stiffness hybrid dual-mode two-finger soft gripper can deform in an arched state at a temperature of about 50 degrees Celsius, and this deformation can drive the spring steel sheet 21 to undergo elasticity. Deformation, by changing the shape, the bending moment of the entire piece of spring steel sheet 21 in the normal direction has also been correspondingly increased.

At the initial stage of heating, the entire spring steel sheet 21 remains flat as a whole, and is not pulled by the memory alloy sheet 23 itself. After raising the heating temperature to more than 50 degrees Celsius, the memory alloy sheet 23 is completely deformed, and the spring steel sheet 21 is subjected to traction, and also changes from flat to arched. The entire deformation process takes about 20 seconds, which can ensure that the variable stiffness hybrid dual-mode two-finger soft gripper can be quickly deformed during actual use.

As shown in Figures 3 and 4, the working principle: when the heating sheet 22 is activated and heated, the memory alloy sheet 23 shrinks to the inside of the claw due to its nature, and is C-shaped at the top view angle, driving the spring steel sheet 21 to produce an arched deformation. At this time, the bending moment of the spring steel sheet 21 in the normal direction is greatly increased, and the maximum grasping force is increased. At this time, the grasping mode is switched to clamping; and when the heating plate 22 is turned off and heated, the memory alloy sheet 23 expands Flat, the bending moment in the normal direction is small, so that the spring steel sheet 21 can realize opposite side bending, and at this time, the grasping mode is switched to envelope.

In summary, the variable stiffness hybrid dual-mode two-finger soft gripper in the above embodiment is a variable stiffness two-finger soft gripper with two grasping modes of envelope and gripping, and can switch grasping modes in real time. Modal to adapt to the grasping process of different objects, the designed variable stiffness two-finger soft hand can ensure the characteristics of both the gripping force of the rigid hand and the flexibility of the soft hand, and can effectively avoid damage or damage to the object.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (9)

1. The utility model provides a two fingers software tongs of mixed bimodal of variable rigidity which characterized in that includes: the device comprises a driving structure, a grabbing structure, a rotating connection structure and a traction structure; the driving structure and the grabbing structure are in rotary connection through the rotary connection structure, and the driving structure pulls the grabbing structure through the traction structure;

snatch the structure and include the hand claw that two symmetries set up, the hand claw includes spring steel sheet, a plurality of heating plate, a plurality of memory alloy piece, the spring steel sheet passes through rotate connection structure with drive structure rotates to be connected, and is a plurality of the heating plate interval sets up the outside of spring steel sheet is surperficial, and is a plurality of memory alloy piece interval sets up the inboard of spring steel sheet is surperficial.

2. The variable stiffness hybrid bimodal soft gripper of claim 1, wherein: the top cover plate is arranged at the upper end of the top support, and the digital steering engine is arranged inside the top support.

3. The variable stiffness hybrid bimodal two-finger grip of claim 2, wherein: the outer surface of the digital steering engine is provided with a connecting block, the inside of the top support is provided with a mounting seat, and the connecting block is detachably connected with the mounting seat.

4. The variable stiffness hybrid bimodal two-finger grip of claim 1, wherein: the outside cover of hand claw is equipped with rather than appearance assorted silica gel cover.

5. The variable stiffness hybrid bimodal two-finger grip of claim 4, wherein: the inner side surface of the silica gel sleeve is provided with a plurality of anti-slip strips.

6. The variable stiffness hybrid bimodal two-finger grip of claim 2, wherein: the rotary connecting structure comprises a first fixing seat, a second fixing seat, a torsion spring and a cylindrical pin, wherein the second fixing seat is arranged at the top of the spring steel sheet, the first fixing seat is arranged at the lower end of the top support, and the second fixing seat is rotatably connected with the first fixing seat through the cylindrical pin and the torsion spring.

7. The variable stiffness hybrid bimodal two-finger grip of claim 6, wherein: the traction structure comprises a traction rope and a plurality of connecting seats, the connecting seats are arranged on the inner side surface of the spring steel sheet at intervals and are arranged in a staggered mode with the memory alloy sheet, one end of the traction rope is connected with the digital steering engine, and the other end of the traction rope sequentially penetrates through the top support, the second fixing seat and each connecting seat and is fixedly connected with the connecting seat located at the tail end.

8. A method of gripping a variable stiffness hybrid bimodal two-finger soft grip, characterized in that the variable stiffness hybrid bimodal two-finger soft grip according to any one of claims 1 to 7 is used for gripping an article, comprising the steps of:

s1: judging according to the properties of the contact surfaces of the two-finger soft body gripper and the object, and selecting an envelope gripping mode or a gripping mode for gripping;

s2: when an enveloping grabbing mode is selected, the traction rope drives the spring steel sheet to be bent from bottom to top under the rotation of the digital steering engine, and the bent deformation is fitted with the outer surface of an object, so that an enveloping state is achieved; when the clamping mode is selected, the heating plate is powered by the direct current source, the temperature rises, the memory alloy sheet on the inner surface of the spring steel sheet is bent along with the rise of the temperature and is C-shaped, under the limiting action of the silica gel sleeve, the inner sides of the claws are flat and non-concave, and finally the two claws are drawn to approach the center of the object through the drawing of the traction rope to form the clamping mode.

9. The method of claim 8, wherein the gripping method comprises the following steps: in the step S1, when the contact surface of the two-finger gripper and the object has a change in curvature, the object is gripped in an envelope gripping mode; when the contact surface of the two-finger soft gripper and the object has no radian change, the object is gripped in a gripping mode.

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