CN115416013A - Variable stiffness soft elongation actuator and soft gripper based on cross fiber interference - Google Patents

Abstract

The invention provides a variable stiffness soft extension driver based on cross fiber interference and a soft gripper. The driver includes: a corrugated tube with both ends closed and provided with a first air hole and a second air hole; The variable stiffness structure in the tube, the variable stiffness structure includes two fiber units and a soft cover, each fiber unit includes a base and a fiber bundle, one end of the fiber bundle is fixedly connected to the base, the two fiber units are arranged in the soft cover, and the two bases are respectively sealed and connected to the soft cover At both ends of the cover, two fiber bundles are placed together in the soft cover, the two bases are respectively connected to the two ends of the bellows, the first air hole communicates with the space between the bellows and the soft cover, and the second air hole communicates with the inside of the soft cover. Beneficial effects of the present invention: the variable stiffness structure of the driver can follow the stretching of the driver, effectively improving the stretch forming stability of the soft elongation driver; solving the problem of local cavities caused by stretching in the traditional variable stiffness structure, with global Variable stiffness properties.

Description

Variable stiffness soft elongation actuator and soft gripper based on cross fiber interference

technical field

The invention relates to the technical field of soft actuator equipment, in particular to a variable stiffness soft elongation actuator based on cross fiber interference and a soft gripper.

Background technique

Robotic grippers can replace human hands to grab objects, and have been widely used in all aspects of production and life, playing an important role in realizing industrial automation. Measuring the design level of a manipulator mainly depends on evaluation indicators such as grasping reliability, operational flexibility, and environmental adaptability. However, traditional manipulators are mainly made of rigid materials, usually with high mass and lack of flexibility, and face great challenges in handling complex and changeable application scenarios. In recent years, soft hands designed and manufactured using soft materials have attracted widespread attention from scholars and institutions at home and abroad, and provided us with new ideas for improving manipulators. The soft hand is based on materials science and mechanics, and uses the mechanical intelligence of the soft material itself to make the gripper have flexible and efficient grasping performance.

The software driver is the core execution part of the software gripper, which is of great significance to the performance improvement of the software gripper. Soft actuators with elongation function are one of the most common actuators that can be applied in soft grippers and provide a promising solution for adjusting the grasping range of grippers. However, soft elongation actuators struggle to maintain the stability of their stretched shape under high loads. For example, when the soft gripper needs to grab a heavy and large object, due to the softness of the soft elongation driver, the load capacity is poor, and it is difficult to resist the reverse force from the grasped object, which will cause poor grip. A stable situation occurs.

In recent years, variable stiffness technology has been developed and considered as an effective way to solve the problem of soft actuator softness. There are two types of existing stiffness-variable technologies, one is to change the stiffness through the intelligent material method, and the other is to change the stiffness through mutual extrusion between structures (commonly known as the interference method). The former changes the molecular properties of the material itself by applying external stimuli such as light, electricity, and heat, thereby changing from a soft state to a hard state. The latter changes the stiffness by aggregating granular media, layered media, etc. within a film, and then applying negative pressure to compact the media.

However, existing variable stiffness techniques have significant limitations when applied to elongational actuators. Whether it is the smart material method or the negative pressure interference method, it is difficult to apply to the elongation actuator. This is because variable stiffness materials/variable stiffness structures are not inherently stretchable and cannot stretch as the elongation actuator stretches. Taking the particle interference method as an example, when the particle interference structure is stretched, a cavity area will appear due to the stretching, and the stiffness cannot be changed globally, that is, the variable stiffness function will fail. The same is true for the layer interference method.

Contents of the invention

In view of this, in order to solve the problem that the existing variable stiffness structure is difficult to be applied to the soft body elongation driver, resulting in the problem that the driver has low hardness during operation, and is prone to deformation and grasping relaxation, the embodiment of the present invention provides a cross-based Fiber interference variable stiffness soft body elongation driver and soft gripper.

An embodiment of the present invention provides a variable stiffness soft body elongation driver based on cross fiber interference, including:

a bellows closed at both ends and provided with a first vent hole and a second vent hole;

And a variable stiffness structure arranged in the bellows, the variable stiffness structure includes two fiber units and a soft cover, each fiber unit includes a base and a fiber bundle, one end of the fiber bundle is fixedly connected to the base, and the two fiber units The fiber unit is arranged in the soft cover, and the two bases are respectively sealed and connected to the two ends of the soft cover, the two fiber bundles are arranged together in the soft cover, and the two bases are respectively connected to the two ends of the bellows, The first vent hole communicates with the space between the bellows and the soft cover, and the second vent hole communicates with the interior of the soft cover.

Further, one end of the fiber bundle is fixed on half of the base.

Further, the soft cover is cylindrical, and the fiber bundle is semi-cylindrical.

Further, the soft cover is arranged coaxially with the bellows.

Further, the fiber bundle includes a plurality of cylindrical fiber strips.

Further, the corrugated pipe includes a pipe body with an open upper end, and an end cap sealingly connected with the upper port of the pipe body, and the first vent hole and the second vent hole are arranged on the end cap.

In addition, on the basis of the above-mentioned cross-fiber interference-based variable-stiffness soft elongation actuator, an embodiment of the present invention also provides a soft gripper, including two above-mentioned cross-fiber interference-based variable-stiffness soft elongation actuators, and a V-shaped A bracket and two rocker arms, the two rocker arms are respectively hinged to the two ends of the bracket, and each driver is connected to the rocker arm and the bracket to drive the rocker arm to rotate relative to the bracket.

Further, two upper mounting plates are provided on the outside of the bracket, and a lower mounting plate is provided at one end of each rocker arm close to the bracket, and the two ends of each driver are respectively installed on the upper mounting plate and the upper mounting plate. on the mounting plate described below.

Further, the rocker arm is L-shaped, its middle part is hinged to one end of the bracket, its upper end forms the lower mounting plate, and its lower end is used to clamp objects.

Further, the lower end of the rocker arm is provided with a contact airbag.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

1. A variable stiffness soft body elongation driver based on cross fiber interference of the present invention, the variable stiffness structure inside the driver can follow the stretching of the driver, effectively improving the stretch forming stability of the soft body elongation driver.

2. A soft body elongation driver based on cross-fiber interference variable stiffness of the present invention solves the problem of local cavities caused by stretching in the traditional particle interference variable stiffness/layer interference variable stiffness, and has the characteristics of global variable stiffness .

3. A variable stiffness soft body elongation actuator based on cross-fiber interference of the present invention has versatility and can be applied to most soft body elongation actuators.

4. A soft gripper of the present invention can automatically adjust the gripping distance, realize a stable adjustment gripping range, and can effectively resist the reverse force of objects, improving the stability of the soft gripper when adjusting the gripping distance .

Description of drawings

FIG. 1 is a schematic diagram of a variable stiffness soft body elongation driver 100 based on cross fiber interference in the present invention;

Fig. 2 is a top view of a variable stiffness soft body elongation driver based on cross fiber interference in the present invention;

Fig. 3 is an exploded view of a variable stiffness soft body elongation driver based on cross fiber interference in the present invention;

Fig. 4 is A-A sectional schematic diagram among Fig. 2;

Figure 5 is an exploded view of the variable stiffness structure;

Fig. 6, Fig. 7 are the schematic diagrams of the force of the fiber bundle;

Fig. 8 is a schematic diagram of the staggering of the fiber bundles of the two fiber units when the bellows is elongated;

Fig. 9 is the schematic diagram of the injection mold of bellows;

Fig. 10 is a schematic diagram of a normal state of a software gripper of the present invention;

11 and 12 are schematic diagrams of a grasping state of a soft gripper of the present invention.

In the figure: 100-variable stiffness soft body elongation driver based on cross fiber interference, 1-bellows, 2-variable stiffness structure, 3-tube body, 4-end cover, 5-first vent hole, 6-second vent hole , 7-soft cover, 8-fiber unit, 9-fiber bundle, 10-base, 11-outer mold, 12-inner mold, 101-bracket, 102-rocker arm, 103-upper mounting plate, 104-lower mounting plate , 105 - contact the airbag.

detailed description

In order to make the purpose, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings. The following is a preferred one of the multiple possible embodiments of the present invention, intended to provide a basic understanding of the present invention, but not intended to identify key or decisive elements of the present invention or limit the scope of protection.

In all examples shown and discussed herein, any specific values should be construed as exemplary only, and not as limitations. Therefore, other examples of the exemplary embodiment may have different values.

Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered part of the Authorized Specification.

It should be noted that like numerals and letters denote like items in the following figures, therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures. At the same time, it should be understood that, for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral Ground connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Referring to FIGS. 1 , 2 , 3 , 4 and 5 , an embodiment of the present invention provides a variable stiffness soft body elongation actuator 100 based on cross fiber interference, including a bellows 1 and a variable stiffness structure 2 .

As shown in FIGS. 3 and 4 , the bellows 1 is hollow, and the bellows 1 will perform linear elongation after being inflated. Both ends of the bellows 1 are closed, and a first air hole 5 and a second air hole 6 are provided.

Specifically, the corrugated pipe 1 includes a pipe body 3 and an end cap 4 , the lower end of the pipe body 3 is closed and the upper end is open. The end cap 4 and the upper port of the tube body 3 can be glued together to realize the sealed connection between the end cap 4 and the tube body 3 .

The first ventilation hole 5 is arranged on the end cover 4 near the edge, and the second ventilation hole 6 is arranged at the center of the end cover 4 . Both the first ventilation hole 5 and the second ventilation hole 6 can be plugged with a trachea to realize inflation or suction.

The corrugated pipe 1 can be made by injection molding of silica gel. The injection mold used for the pipe body 3 is shown in FIG. The inner cavity of the inner mold 12 has a corrugated inner core, and the inner core of the inner mold 12 is inserted into the inner cavities of the two outer molds 11 . When making the tube body 3 , pour liquid silica gel from the upper opening of the injection mold, wait for the silica gel to solidify, and then remove the mold to obtain the tube body 3 . Similarly, the end cap 4 can be obtained by using silicone injection molding.

As shown in Figures 4 and 5, the variable stiffness structure 2 is arranged in the bellows 1, the variable stiffness structure 2 mainly includes two fiber units 8 and a soft cover 7, and each fiber unit 8 includes a base 10 and fiber bundles9.

The soft cover 7 is a hollow cylinder with openings at both ends, and is made of silica gel. The two fiber units 8 are accommodated in the soft case 7 . One end of the fiber bundle 9 is fixedly connected to the base 10. Here, the fiber bundle includes a plurality of cylindrical fiber strips, one end of each fiber strip is fixedly connected to the base 10, and the other end is freely arranged. Preferably, one end of the fiber bundle 9 is fixed on half of the base 10 . As in this embodiment, the base 10 is circular, the fiber bundle 9 is semi-cylindrical and one end is just bonded to the semi-circular area of the base 10 .

The two fiber units 8 are arranged in the soft cover 7 , and the two bases 10 are respectively sealed and connected to the two ends of the soft cover 7 , and the two fiber bundles 9 are arranged together in the soft cover 7 . Here, the two bases 10 are respectively embedded in the two ends of the soft cover 7 and are sealed and connected with the two ends of the soft cover 7 by glue bonding. In the software cover 7.

When making the variable stiffness structure 2, the fiber strips of the fiber bundle 9 use Polyjet 3D printing technology to directly 3D print soft rubber materials. The soft cover 7 can be 3D printed using Polyjet 3D printing technology, or can be made by injection molding. In this embodiment, the fiber strip has a Shore stiffness of 70A, and the soft cover has a Shore stiffness of 30A.

After the variable stiffness structure 2 is manufactured, it is put into the bellows 1 as a whole, and the soft cover 7 should be coaxially arranged with the bellows 1 as far as possible. And the two bases 10 of the two fiber units 8 are respectively connected to the two ends of the bellows 1, as in this embodiment, the two bases 10 are respectively connected to the bottom surface of the tube body 3 and the top surface of the end cover 4 Adhesive connection.

After the variable stiffness structure 2 and the bellows 1 are assembled, the first vent hole 5 communicates with the space between the bellows 1 and the soft cover 7 . The center of the upper base 10 is provided with a perforation, and the perforation is vertically aligned with the second ventilation hole 6 so that the second ventilation hole 6 communicates with the interior of the soft cover 7 .

When the variable-stiffness soft elongation actuator 100 is working based on cross-fiber interference, the inside of the bellows 1 can be ventilated through the first air hole, and the bellows 1 is stretched and bent under the action of air pressure. Since there is no obstacle between the fiber bundles 9 of the two fiber units 8 , the fiber bundles of the two fiber units can be smoothly staggered as shown in FIG. 8 . And in order to adapt to the bending of the bellows 1 , the fiber bundles of the two fiber units may be twisted as shown in FIG. 6 and/or bent as shown in FIG. 7 . Then, negative pressure is drawn into the soft cover 7 through the second air hole 6 to make the fiber bundle 9 hard, so that the overall rigidity of the driver 100 can be changed. In this way, the problem that the variable stiffness material/variable stiffness structure itself is not stretchable and cannot be stretched with the stretching of the elongation driver is overcome.

In addition, on the basis of the above-mentioned variable stiffness soft elongation actuator 100 based on cross-fiber interference, the embodiment of the present invention also provides a soft gripper. As shown in FIG. 10 , the soft gripper mainly includes two above-mentioned cross-fiber interference variable stiffness soft elongation drivers 100 , a V-shaped bracket 101 and two rocker arms 102 .

The bracket 101 diverges at a certain angle for mounting the two rocker arms 102 and the two drivers 100 . Specifically, the two rocker arms 102 are respectively hinged with the two ends of the bracket 101. As in this embodiment, the rocker arms 102 are L-shaped. One end is connected so that the swing arm 102 can rotate around one end of the bracket 101 .

Each driver 100 connects the rocker arm 102 and the bracket 101 to drive the rocker arm 102 to rotate relative to the bracket 101 . Specifically, the outer side of the bracket 101 is provided with two upper mounting plates 103, and each rocker arm 102 is provided with a lower mounting plate 104 near one end of the bracket, where the upper end of the rocker arm 102 directly forms the lower mounting plate 104, the two ends of each driver 100 are respectively installed between the upper mounting plate 103 and the lower mounting plate 104, the extension of the driver 100 can drive the two rocker arms 102 to rotate, so that the two The lower ends of the rocker arms 102 are relatively close to each other.

The lower end of the swing arm 102 is used for clamping objects. Preferably, the lower end of the rocker arm 102 is provided with a contact airbag 105, through which the contact airbag 105 directly contacts the object, which can play a buffering role and prevent damage to the object.

The above-mentioned software gripper is designed based on the design idea of the bionic human hand, which simulates the opening and closing posture of the fingers of the human hand, and can dexterously grasp objects of multiple sizes and shapes. As shown in Figures 11 and 12, when grabbing, we first drive the bellows 1 of the two drivers 100 to extend and/or bend, so that the lower ends of the two rocker arms 102 clamp the object, and then the variable stiffness structure 100 Vacuum is applied inside to increase the rigidity, and then the object is lifted, which can resist the reverse force from the object to the grasp during the grasping process, and has the beneficial effect of grasping stability.

In this article, the orientation words such as front, rear, upper, and lower involved are defined by the parts in the drawings and the positions between the parts in the drawings, just for the clarity and convenience of expressing the technical solution. It should be understood that they are relative concepts and can be changed correspondingly according to different ways of use and placement, and the use of the location words should not limit the scope of protection claimed in this application.

In the case of no conflict, the above-mentioned embodiments and features in the embodiments herein may be combined with each other.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. A variable stiffness soft body elongation driver based on cross fiber interference, characterized in that it comprises: a bellows closed at both ends and provided with a first vent hole and a second vent hole; And a variable stiffness structure arranged in the bellows, the variable stiffness structure includes two fiber units and a soft cover, each fiber unit includes a base and a fiber bundle, one end of the fiber bundle is fixedly connected to the base, and the two fiber units The fiber unit is arranged in the soft cover, and the two bases are respectively sealed and connected to the two ends of the soft cover, the two fiber bundles are arranged together in the soft cover, and the two bases are respectively connected to the two ends of the bellows, The first vent hole communicates with the space between the bellows and the soft cover, and the second vent hole communicates with the interior of the soft cover. 2. The variable stiffness soft elongation actuator based on cross-fiber interference according to claim 1, wherein one end of the fiber bundle is fixed to half of the base. 3. The soft body elongation actuator with variable stiffness based on cross-fiber interference according to claim 1, characterized in that: the soft body sleeve is cylindrical, and the fiber bundle is semi-cylindrical. 4. The soft body elongation actuator with variable stiffness based on cross-fiber interference according to claim 3, characterized in that: the soft body sleeve is arranged coaxially with the bellows. 5 . The variable stiffness soft elongation actuator based on cross fiber interference according to claim 1 , wherein the fiber bundle comprises a plurality of cylindrical fiber strips. 5 . 6. The variable-stiffness software elongation actuator based on cross-fiber interference as claimed in claim 1, wherein the bellows comprises a pipe body with an open upper end, and an end cap sealingly connected with the upper port of the pipe body, so that The first air hole and the second air hole are arranged on the end cover. 7. A soft gripper, characterized in that it comprises two soft extension drivers based on cross-fiber interference variable stiffness according to any one of claims 1 to 6, and also includes a V-shaped bracket and two rocker arms. The rocker arm is respectively hinged to two ends of the bracket, and each driver is connected to the rocker arm and the bracket to drive the rocker arm to rotate relative to the bracket. 8. The software gripper according to claim 7, characterized in that: two upper mounting plates are provided on the outside of the bracket, each of the rocker arms is provided with a lower mounting plate near the end of the bracket, and each of the Both ends of the driver are installed on the upper mounting plate and the lower mounting plate respectively. 9 . The software gripper according to claim 8 , wherein the rocker arm is L-shaped, the middle part is hinged to one end of the bracket, the upper end forms the lower mounting plate, and the lower end is used for clamping objects. 10. The soft gripper according to claim 9, wherein a contact airbag is provided at the lower end of the rocker arm.

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