CN112809727B - A rope traction rigid-flexible coupling variable stiffness gripper - Google Patents

Abstract

The invention provides a rope traction rigid-flexible coupling variable-rigidity gripper, which comprises an inner side flexible mechanism, an outer side rigid gripping mechanism and a driving motor, wherein the inner side flexible mechanism is connected with the outer side rigid gripping mechanism; the inner side flexible mechanism is formed by connecting a flexible left clamping assembly and a flexible right clamping assembly which are symmetrically arranged through a connecting piece; the outer rigid grabbing mechanism comprises a left driving assembly, a right driving assembly, a base, a rigid left clamping assembly and a rigid right clamping assembly which are symmetrically arranged; the flexible left clamping assembly and the flexible right clamping assembly are connected with the base through a connecting piece; one end of the rigid left clamping assembly is connected with the flexible left clamping assembly, and the other end of the rigid left clamping assembly is hinged with the base; one end of the rigid right clamping component is connected with the flexible right clamping component, and the other end of the rigid right clamping component is hinged with the base; and the left driving assembly and the right driving assembly are respectively arranged inside the rigid left clamping assembly and the rigid right clamping assembly and are connected with a driving motor. The gripper has variable-rigidity gripping capability, so that flexible and safe gripping of objects is realized.

Description

A rope traction rigid-flexible coupling variable stiffness gripper

technical field

The invention relates to the technical field of variable stiffness grippers, and more particularly, to a rope traction rigid-flexible coupling variable stiffness gripper.

Background technique

The variable stiffness gripper refers to the control of the stiffness of the gripper itself. It can realize the gripping operation of different complex and fragile objects by changing its own stiffness in different operating environments, making up for the traditional gripper to a certain extent. The problems of excessive rigidity and insufficient rigidity and grasping force of the soft gripper due to its high flexibility have better safety and adaptability. Therefore, it is widely used in the fields of intelligent manufacturing and industrial robots mainly based on structure and intelligent materials.

In the gripping tasks of industry and daily life, on the one hand, the end effector of the robotic arm is often required to perform stable, adaptive and variable stiffness gripping operations on fragile objects, so as to achieve multiple gripping objects with complex sizes and different shapes. On the other hand, it is often necessary to simulate the size of the end gripper and use rope traction as the drive, which can meet the requirements of lightness, flexibility and low cost during the grasping process, so as to achieve versatility and economy. and multi-grip mode gripping operations. Due to the above two reasons, the simultaneous realization of variable stiffness, human-like hand and rope underactuation is a research hotspot in the field of industrial robots and intelligent manufacturing.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the shortcomings and deficiencies in the prior art, and provide a rope traction rigid-flexible coupling variable stiffness gripper, the gripper has the gripping ability of variable stiffness, thereby realizing flexible and safe gripping of objects; At the same time, the gripper has the advantages of small size, simple structure, low cost, etc., and uses fewer drivers to drive the freedom of the gripper joints, which is conducive to the realization of safe grasping of multiple grasping objects with complex sizes and different shapes , suitable for industrial robots and intelligent manufacturing and other fields.

In order to achieve the above purpose, the present invention is achieved through the following technical solutions: a rope traction rigid-flexible coupling variable rigidity gripper, which is characterized in that: it includes an inner flexible mechanism, an outer rigid grabbing mechanism and a drive motor; the inner flexible The mechanism is composed of symmetrically arranged flexible left clamping components and flexible right clamping components connected by connecting pieces; the outer rigid grasping mechanism includes a left driving component, a right driving component, a base, and symmetrically arranged rigid left clamping components and rigid a right clamping assembly; the flexible left clamping assembly and the flexible right clamping assembly are connected with the base through a connecting piece; one end of the rigid left clamping assembly is connected with the flexible left clamping assembly, and the other end is hinged with the base; the One end of the rigid right clamping component is connected with the flexible right clamping component, and the other end is hinged with the base; the left driving component and the right driving component are respectively arranged inside the rigid left clamping component and the rigid right clamping component and are connected with the driving motor , to realize that the driving motor drives the rigid left clamping assembly and the rigid right clamping assembly to perform clamping or opening movement through the left driving assembly and the right driving assembly.

The flexible left clamping assembly has the same structure as the flexible right clamping assembly, and includes a top clamping rod, a first double-sided flexible rotating pair, a flexible clamping rod and a second double-sided flexible rotating pair that are connected in sequence; the flexible Both the left clamping component and the flexible right clamping component are connected with the connecting piece through the second double-sided flexible rotating pair.

The first double-sided flexible rotating pair and the second double-sided flexible rotating pair are both perfect circular double-sided flexible rotating pairs. The main features of the perfect circular double-sided flexible rotating pair used in the present invention are: simple structure, easy to manufacture, no need for assembly and maintenance, no friction loss, and the topological structure is similar to its corresponding rigidity mechanism, and the multi-concentrated flexibility type is flexible. The kinematic pair replaces the traditional kinematic pair.

The surface of the top clamping rod is provided with a tooth-like structure for increasing the frictional force.

The inner flexible mechanism is an integrally formed rubber member. The basic principles of material selection of the inner flexible mechanism: First, the ratio of its strength limit and elastic modulus is mainly considered. Such as: polypropylene, polysilicon, rubber, etc. are ideal non-metal elastic materials. Second, fully consider the fatigue resistance of the material. Ensure that the material does not experience tension relaxation or creep when deforming. Third, in the case of satisfying the above two points, consider the economical applicability of the material.

The rigid left clamping assembly has the same structure as the rigid right clamping assembly, and both include a last finger and a root finger that are hinged in sequence; the rigid left clamping assembly is hinged with the flexible left clamping assembly through the last finger, and is connected to the flexible left clamping assembly through the root finger. The base is hinged; the rigid right clamping component is hinged with the flexible right clamping component through the last finger, and is hinged with the base through the root finger.

The left drive assembly and the right drive assembly have the same structure, and both include elastic traction devices and transmission devices arranged in the inner cavity of the last finger and the root finger;

The elastic traction device includes a stretched rebound spring and a torsion spring; the torsion spring is arranged at the hinge link between the root finger and the base; one end of the stretched rebound spring is fixed on the last finger, and the other end goes around the end in turn. The hinge chain between the finger and the root finger and the hinge chain between the root finger and the base are finally fixed at the connection between the connecting piece and the base to form the extensor tendon structure of the gripper.

The transmission device comprises a traction rope, a first winding column arranged in the inner cavity of the last finger, and a second winding column and a third winding column both arranged in the inner cavity of the root finger; the first winding column and The second winding post is arranged close to the hinge chain between the last finger and the root finger, and the third winding post is arranged close to the hinge link between the root finger and the base;

The traction rope goes around the first winding column, the hinged chain between the last finger and the root finger, the second winding column, the third winding column and the hinged chain between the root finger and the base in sequence, and finally passes through the base to connect with the drive motor , the flexor tendon structure that forms the gripper.

The traction rope and the stretch-resilient spring are connected as a whole.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The rope traction rigid-flexible coupling variable-stiffness gripper of the present invention has the gripping ability of variable stiffness, thereby realizing flexible and safe gripping of objects; at the same time, the gripper has the advantages of small size, simple structure, low cost, etc. Fewer drivers drive the joint freedom of the gripper, which is conducive to the realization of safe grasping of multiple grasped objects with complex sizes and different shapes, and is suitable for industrial robots and intelligent manufacturing and other fields.

2. The rope traction rigid-flexible coupling variable stiffness gripper of the present invention can realize plane gripping under open-loop gripping control, that is, precise gripping and dynamic gripping, and is applied to complex hardware parts, vulnerable special-shaped parts, etc. in the industrial field , which can be applied to grab most of the common items in life, and has good human-computer interaction.

3. The variable stiffness principle realized by the rigid-flexible coupling of the gripper of the present invention enables the gripper to adapt to more objects and to grasp them accurately; The object is grasped accurately, and the contact friction of the grasped object is increased at the same time, and the success rate of grasping is increased.

4. The present invention adopts the rope traction under-actuated driving mode, which has a simple structure, a size similar to a human hand, and good self-adaptability. It can realize multiple working modes without requiring a large number of drivers and complex control algorithms.

Description of drawings

1 is a perspective view of a rope traction rigid-flexible coupling variable rigidity gripper of the present invention;

2 is a perspective view of a flexible mechanism of a rope traction rigid-flexible coupling variable-rigidity gripper of the present invention;

Fig. 3 is a front view of a rope traction rigid-flexible coupling variable rigidity gripper of the present invention (and a cross-sectional view of the left gripping and base);

Fig. 4 is a rope path of the elastic traction device of a rope traction rigid-flexible coupling variable stiffness gripper of the present invention;

5 is an enlarged view of the top clamping rod of a rope traction rigid-flexible coupling variable rigidity clamp of the present invention;

6 is a schematic diagram of the precise grasping of a rope traction rigid-flexible coupling variable-stiffness gripper of the present invention;

7 is a schematic diagram of the power grabbing of a rope traction rigid-flexible coupling variable rigidity gripper of the present invention;

8 is a schematic diagram of the joint shaft of the root finger and the base of a rope traction rigid-flexible coupling variable rigidity gripper of the present invention;

9 is a schematic diagram of the first winding column, the second winding column and the third winding column of a rope traction rigid-flexible coupling variable stiffness gripper of the present invention;

Among them, 1 is the top clamping rod; 2 is the first double-sided flexible rotating pair; 3 is the flexible clamping rod; 4 is the second double-sided flexible rotating pair; 5 is the connecting piece; 6 is the last finger; 7 is the root finger 8 is the base; 9 and 15 are rivets; 10 is the first winding column; 11 and 14 are hinged chains; 12 is the second winding column, 13 is the third winding column; 16 is the small hole; 17 18 is a tension spring; 19 is a traction rope; 20 is a torsion spring; 21 is a toothed structure; 22 is a miniature bearing; 23 is a groove; 24 is a nut.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

Example

As shown in FIGS. 1 to 9 , a rope traction rigid-flexible coupling variable-rigidity gripper of the present invention includes an inner flexible mechanism, an outer rigid grabbing mechanism and a drive motor 17, wherein the inner flexible mechanism is composed of symmetrically arranged flexible left clamps The holding component and the flexible right holding component are connected by the connecting piece 5 . The outer rigid gripping mechanism includes a left driving component, a right driving component, a base 8, and a rigid left clamping component and a rigid right clamping component arranged symmetrically. The flexible left clamping component and the flexible right clamping component of the present invention are connected by connecting pieces. 5 and rivets 15 are connected to the base 8, one end of the rigid left clamping assembly is connected to the flexible left clamping assembly through rivets 9, the other end is hinged to the base 8, and one end of the rigid right clamping assembly is connected to the flexible right clamping assembly through rivets 9. connected, the other end is hinged with the base 8, and the left drive assembly and the right drive assembly are respectively arranged inside the rigid left clamp assembly and the rigid right clamp assembly and connected with the drive motor 17, so that the drive motor 17 can be driven by the left drive assembly and the right drive assembly. The assemblies drive the rigid left gripping assembly and the rigid right gripping assembly for gripping or spreading motion.

Specifically, the flexible left clamping assembly and the flexible right clamping assembly have the same structure, including a top clamping rod 1, a first double-sided flexible rotating pair 2, a flexible clamping rod 3 and a second double-sided flexible rotating pair connected in sequence. Pair 4, the flexible left clamping assembly and the flexible right clamping assembly are both connected to the connecting member 5 through the second double-sided flexible rotating pair 4, wherein the first double-sided flexible rotating pair 2 and the second double-sided flexible rotating pair 4 All are round double-sided flexible rotating pairs. The main features of the perfect circular double-sided flexible rotating pair used in the present invention are: simple structure, easy to manufacture, no need for assembly and maintenance, no friction loss, and the topological structure is similar to its corresponding rigidity mechanism, and the multi-concentrated flexibility type is flexible. The kinematic pair replaces the traditional kinematic pair.

In order to increase the frictional contact of holding the object, the surface of the top gripping rod 1 is provided with a tooth-like structure 21 for increasing the frictional force, which is beneficial to gripping thin objects, such as coins, on a plane. Similar to the role of fingernails when the human hand is accurately pinching coins.

The inner flexible mechanism of the present invention is an integrally formed rubber member. The basic principles of material selection of the inner flexible mechanism: First, the ratio of its strength limit and elastic modulus is mainly considered. Such as: polypropylene, polysilicon, rubber, etc. are ideal non-metal elastic materials. Second, fully consider the fatigue resistance of the material. Ensure that the material does not experience tension relaxation or creep when deforming. Third, in the case of satisfying the above two points, consider the economical applicability of the material.

The rigid left clamping assembly of the present invention has the same structure as the rigid right clamping assembly, and both include a last finger 6 and a root finger 7 that are hinged in sequence. The rigid left clamping assembly is hinged with the flexible left clamping assembly through the last finger 6, and the root The fingers 7 are hinged with the base 8 , while the rigid right gripping assembly is hinged with the flexible right gripping assembly through the last finger 6 and hinged with the base 8 through the root finger 7 .

In the present invention, the hinge 11 at the joint of the last finger 6 and the root finger 7 is composed of a joint shaft, a miniature bearing and an embedded nut. The two ends of the joint shaft pass through two miniature bearings. The inner diameter of the miniature bearings is 4mm and the outer diameter is 6mm, and they are respectively embedded in the joint of the last finger 6 and the root finger 7. The joint shaft is fixed by the embedded nut, so that the end finger 6 and the root finger 7 are fixed. Hinge of root finger 7. In the present invention, the hinge 14 at the joint between the root finger 7 and the base 8 is composed of a joint shaft, a miniature bearing 22 and an embedded nut. Both ends of the joint shaft are fixed at the shell of the base 8 by embedded nuts, the joint shaft passes through two miniature bearings 22 embedded in the joint of the root finger 7, and a groove 23 is set to realize the root finger 7 of the gripper. Hinged to base 8.

The left drive assembly and the right drive assembly of the present invention have the same structure, and both include an elastic traction device and a transmission device arranged in the inner cavity of the last finger 6 and the root finger 7. The transmission device encircles the elastic traction device and passes through the base 8 and the drive motor. 17 connections. Among them, the elastic traction device includes a tensile rebound spring 18 and a torsion spring 20. The torsion spring 20 is arranged at the hinge 14 between the root finger 7 and the base 8, and the torsion spring 20 passes through the joint shaft and is installed in the groove 23. One end of the wire of the torsion spring 20 is at the root finger 7 , and the other end is at the base 8 . When the gripper finishes gripping the object, the root finger 7 can be controlled to return to the original open position by the elastic force of the torsion spring 20 .

The tensile rebound spring 18 is an elastic element made of elastic material, one end of which is fixed on the last finger 6, and the other end goes around the joint shaft of the hinge chain 11 of the last finger 6 and the root finger 7 in turn, as well as the root finger 7 and the base. 8 of the joint axis of the hinged chain 14, the tension spring 18 and the torsion spring 20 are positioned parallel to each other and are not in contact. Finally, the tensile spring 18 is fixed to the rivet 15 at the connection between the connector 5 and the base 8 to form the extensor tendon structure of the holder. The design of the extension spring 18 can satisfy the initial state that the gripper remains open, which is convenient for the grasping operation of larger objects. The groove 23 of the present invention is for fixing the torsion spring 20 to prevent the extensor tendon or flexor tendon of the holder from being interfered by the torsion spring 20 .

The transmission device of the present invention includes a traction rope 19, a first winding column 10 arranged in the inner cavity of the last finger 6, and a second winding column 12 and a third winding column 13 both arranged in the inner cavity of the root finger 7, wherein , the first winding post 10 and the second winding post 12 are arranged close to the hinge chain 11 of the last finger 6 and the base finger 7 , and the third winding post 13 is arranged close to the hinge link 14 of the base finger 7 and the base 8 . The traction rope 19 goes around the first winding column 10 , the joint shaft of the hinged chain 11 of the last finger 6 and the root finger 7 , the second winding column 12 , the third winding column 13 and the hinge of the first finger 7 and the base 8 in turn. The joint shaft of the chain 14 finally passes through the reserved hole 16 provided in the base 8 and is connected to the drive motor 17 to form the flexor tendon structure of the gripper. Specifically, the lower side of the first winding column 10 is in contact with the traction rope 19 , and the two ends of the first winding column 10 respectively pass through two mutually symmetrical reserved holes on the shell of the last finger 6 and are fixed by nuts 24 . The nuts at both ends are embedded with the last finger 6 shell. The lower sides of the second winding column 12 and the third winding column 13 are in contact with the traction rope 19 . Embedded and root refers to 7 shells.

In the present invention, the first winding column 10, the second winding column 12, the third winding column 13 and the joint shaft of the hinge chain convert the rotational motion of the driving motor 17 into a plane motion of the rope pulling the left and right clamping. The extensor tendon structure and the flexor tendon structure of the holder of the invention have the characteristics of simple structure, simple principle and low cost, and have low requirements on the size of the original holder, which can be made into the size of a human hand.

The traction rope 19 of the present invention is connected with the tensile spring 18 as a whole. When the two pass through the last finger 6 and the root finger 7, they are connected through the gap between the bottom end of the last finger 6, the top end of the root finger 7 and the base 8. The traction rope 19 is fixed at the top end of the last finger 6, and passes through the lower side of the first winding column 10, the upper end of the hinged chain 11, the lower sides of the second winding column 12 and the third winding column 13, and the upper end of the hinge 14, and passes through the pre-16. The hole is connected to the drive motor 17 . The driving motor 17 winds the traction rope by rotating the inner first winding column 10 , the second winding column 12 and the third winding column 13 , so that the traction rope 19 can be retracted. The pulling force of the driving motor 17 on the traction rope 19 reaches the joint shaft of the hinged chain 14 through the reserved hole 16, and the joint shaft contacts the traction rope 19 to change the direction of the pulling force, so that the pulling force of the traction rope 19 continues to wind the three wires along the traction rope 19. There is an upward force in the direction of the normal to the column tangent, that is, the left clamping component has a force that closes inward from left to right. Symmetrically, the right clamp assembly has a right-to-left-inward closing force. The traction rope 19 passes through the reserved hole 16 of the base as vertically as possible, which can reduce friction. The driving motor 17 can be a servo motor, a stepping motor, or the like. This embodiment has simple structure, small size, and good self-adaptability through the under-actuated driving mode of rope traction, which can realize multiple working modes and does not require a large number of drivers and complex control algorithms.

When the gripper is grasping the object, the opening size of the gripper is optimized according to the two-point gripping and envelope gripping of the grasped object, and the optimal stretched length of the traction rope and the extensor tendon is obtained. The required gripping force of the gripper is calculated by combining the deformation force of the inner flexible mechanism and the rope tension provided by the motor.

In the non-working state of the gripper, due to the elastic force of the extensor tendon structure, the torsion spring 20 and the inner flexible mechanism, the gripper maintains the maximum open state. When the gripper is working, the driving motor 17 is controlled to rotate forward, one end of the traction rope 19 is fixed on the rotating shaft of the driving motor 17, and the other end is fixed on the top of the last finger 6, so that the traction rope 19 is stretched and flexed against the gripper. Tendon structures create tension. In this example, the rotating shaft of the driving motor 17 simultaneously drives the left and right flexor tendon structures of the gripper, so that the left and right fingers of the gripper bend simultaneously, and drive the inner flexible mechanism to bend. As shown in Figure 6, when the gripper is gripping objects with smaller diameters, it can be precisely gripped, and when it contacts the top gripping rod 1 of the flexible left gripping assembly and the flexible right gripping assembly, the rigid The last finger 6 and the root finger 7 of the left gripping assembly and the rigid right gripping assembly are contracted by the flexor tendon structure, which drives the top gripping rod 1 to grab the object inward. As shown in Figure 7, when the gripper grabs an object with a larger diameter, the object is in continuous contact from the last finger 6 to the root finger 7 to ensure its envelope gripping, while the rigid left gripping assembly and rigid right gripping assembly Controlled by the drive motor 17 to complete a complete open-loop grasping control. When the gripper releases the gripped object, the drive motor 17 is reversed. The flexor tendon structure is loosened along the original path, and the gripper is restored to its original state by the elastic force of the extensor tendon structure, the torsion spring and the medial flexible mechanism.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (7)

1. The utility model provides a rope pulls rigid-flexible coupling variable rigidity holder which characterized in that: comprises an inner flexible mechanism, an outer rigid grabbing mechanism and a driving motor; the inner side flexible mechanism is formed by connecting a flexible left clamping assembly and a flexible right clamping assembly which are symmetrically arranged through a connecting piece; the outer rigid grabbing mechanism comprises a left driving assembly, a right driving assembly, a base, a rigid left clamping assembly and a rigid right clamping assembly which are symmetrically arranged; the flexible left clamping assembly and the flexible right clamping assembly are connected with the base through a connecting piece; one end of the rigid left clamping assembly is connected with the flexible left clamping assembly, and the other end of the rigid left clamping assembly is hinged with the base; one end of the rigid right clamping component is connected with the flexible right clamping component, and the other end of the rigid right clamping component is hinged with the base; the left driving assembly and the right driving assembly are respectively arranged in the rigid left clamping assembly and the rigid right clamping assembly and are connected with the driving motor, so that the driving motor drives the rigid left clamping assembly and the rigid right clamping assembly to carry out clamping or stretching movement through the left driving assembly and the right driving assembly;

The rigid left clamping assembly and the rigid right clamping assembly have the same structure and respectively comprise a tail finger and a root finger which are sequentially hinged; the rigid left clamping assembly is hinged with the flexible left clamping assembly through a tail finger and is hinged with the base through a root finger; the rigid right clamping assembly is hinged with the flexible right clamping assembly through a tail finger and is hinged with the base through a root finger;

the left driving assembly and the right driving assembly have the same structure and respectively comprise an elastic traction device and a transmission device which are arranged in the inner cavities of the tail finger and the root finger; the transmission device is wound around the elastic traction device and penetrates out of the base to be connected with the driving motor;

the elastic traction device comprises a tension rebound spring and a torsion spring; the torsion spring is arranged at the hinge chain of the root finger and the base; one end of the tension rebound spring is fixed on the tail finger, and the other end of the tension rebound spring sequentially bypasses the hinge chain of the tail finger and the root finger and the hinge chain of the root finger and the base and is finally fixed at the joint of the connecting piece and the base to form an extensor tendon structure of the holder.

2. The rope pulling rigid-flexible coupling variable stiffness gripper of claim 1, wherein: the flexible left clamping assembly and the flexible right clamping assembly have the same structure and respectively comprise a top end clamping rod, a first double-sided flexible rotating pair, a flexible clamping rod and a second double-sided flexible rotating pair which are sequentially connected; the flexible left clamping assembly and the flexible right clamping assembly are connected with the connecting piece through a second double-sided flexible revolute pair.

3. The rope pulling rigid-flexible coupling variable stiffness gripper of claim 2, wherein: the first double-sided flexible revolute pair and the second double-sided flexible revolute pair are both right circular double-sided flexible revolute pairs.

4. The rope pulling rigid-flexible coupling variable stiffness gripper of claim 2, wherein: and a tooth-shaped structure for increasing friction force is arranged on the surface of the top end clamping rod.

5. The rope pulling rigid-flexible coupling variable stiffness gripper of claim 1, wherein: the inner side flexible mechanism is an integrally formed rubber component.

6. The rope pulling rigid-flexible coupling variable stiffness gripper of claim 1, wherein: the transmission device comprises a traction rope, a first wrapping post arranged in the inner cavity of the tail finger, and a second wrapping post and a third wrapping post which are both arranged in the inner cavity of the root finger; the first wrapping post and the second wrapping post are arranged close to the hinged chain of the tail finger and the root finger, and the third wrapping post is arranged close to the hinged chain of the root finger and the base;

the traction rope sequentially bypasses the first wrapping post, the hinged chain of the tail finger and the root finger, the second wrapping post, the third wrapping post and the hinged chain of the root finger and the base, and finally penetrates out of the base to be connected with the driving motor to form a flexor tendon structure of the clamp holder.

7. The rope pulling rigid-flex coupled variable stiffness clamp of claim 6, wherein: the traction rope and the tension rebound spring are connected into a whole.

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