Regulatable Fluid-Driven Artificial Muscle Module Based on Foldable Assembly and Composition Method

Abstract

The present invention relates to a controllable fluid-driven artificial muscle module based on folding assembly and a composition method. The controllable fluid-driven artificial muscle module based on folding assembly is composed of a D-shaped cross-section silicone tube, a small circular cross-section silicone hose, an elastic element, double-sided tape, a silicone plate and a silicone adhesive. The raw materials used in the artificial muscle module are commercial finished products. The manufacturing steps are simple, the process is concise and clear, and the cost is low. At the same time, by simply adjusting the manufacturing process, different deformation configurations can be obtained, enabling large-range deformation, high output force and high load-bearing capacity. After testing, the gripper assembled by the present invention can successfully grasp objects of different sizes, weights and shapes, and can be applied to soft robots to complete difficult tasks in complex environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of soft robots, and in particular to an adjustable fluid-driven artificial muscle module based on folding assembly and a composition method thereof. Background Art

[0002] The traditional robot structure is composed of rigid components. Rigid robots have a high degree of development, mature technology, and a large number of applications. However, traditional rigid robots have disadvantages such as complex structure, difficulty in manufacturing, high cost, and insufficient flexibility, especially poor adaptability in the process of interacting with the environment. As robots gradually penetrate into people's lives, safe and reliable human-computer interaction processes are increasingly valued. In recent years, a new type of robot field has emerged - soft robots. Soft robots have gradually won people's attention with their excellent environmental adaptability. Different from traditional rigid robots, soft robots are usually made of soft materials. Soft materials can produce large deformations under stimulation, and the actuators as key components of soft robots are made from this. The actuator components made of soft materials show similar performance to biological muscles, usually called artificial muscles. They show inherent flexibility, safety, and environmental adaptability in the process of interacting with the environment, becoming an emerging development direction of actuators. Existing artificial muscle structures mainly include fluid-driven structures, dielectric elastomer structures, hydrogel structures, shape memory alloy structures, etc. Among them, the fluid-driven structure shows stable driving performance and the advantages of large deformation, large output force, and fast response speed. Existing solutions for manufacturing fluid-driven artificial muscles mainly include mold casting, additive manufacturing, and lamination technology. The mold casting production cycle is long, and the finished product is prone to rupture due to bubble problems, and complex structures cannot be processed; the additive manufacturing production technology is complex, requires relatively expensive equipment, and the materials used are limited; lamination technology requires precise interlayer coordination and is prone to failure problems caused by cracks. In summary, the existing methods are relatively complex, with a long manufacturing cycle, and it is difficult to flexibly achieve changes in deformation configuration during use, which limits its further development. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and propose an adjustable fluid-driven artificial muscle module and a composition method based on folding assembly. The raw materials used are commercially available products, the manufacturing steps are simple, the process is concise and clear, and the cost is low. The present invention can obtain different deformation configurations by simply adjusting the manufacturing process, and can achieve large-range deformation, high output force and high load-bearing capacity. It can be applied to soft robots to complete difficult tasks in complex environments.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] The adjustable fluid-driven artificial muscle module based on folding assembly includes a silicone tube with a D-shaped cross-section, a small silicone hose with a circular cross-section, an elastic element, double-sided tape, a silicone plate, and silicone adhesive. Among them, the small silicone hose with a circular cross-section is arranged inside the silicone tube with a D-shaped cross-section along the axis direction of the silicone tube with a D-shaped cross-section to form a folding tube, forming a fluid-driven layer. The convex side of the folding tube is close to the arc top of the silicone tube with a D-shaped cross-section, and the flat side of the folding tube is close to the flat bottom of the silicone tube with a D-shaped cross-section. The elastic unit is arranged on the convex side of the folding tube and nested at the adjacent creases on the convex side to form an extendable limiting layer. The double-sided tape is arranged on the flat side of the folding tube for bonding and fixing adjacent planes. The silicone plate is arranged on the flat side of the folding tube and bonded and fixed to the folding tube through silicone adhesive as a non-extendable limiting layer.

[0006] Moreover, the folding tube is formed by repeatedly folding the combined structure of the silicone tube with a D-shaped cross-section and the small silicone hose with a circular cross-section. A circular hole is opened at the end of the silicone tube with a D-shaped cross-section.

[0007] Moreover, the circular hole opened at the end of the silicone tube with a D-shaped cross-section is connected to a large silicone hose with a circular cross-section through silicone adhesive as the connecting pipeline of the fluid pressure source.

[0008] A composition method of an adjustable fluid-driven artificial muscle module based on folding assembly includes the following steps:

[0009] Step 1: Place the small silicone hose with a circular cross-section inside the silicone tube with a D-shaped cross-section, and draw equidistant scale marks on the surface of the silicone tube with a D-shaped cross-section. These marks are the locations of the subsequent creases. Repeatedly fold the combined structure of the silicone tube with a D-shaped cross-section and the small silicone hose with a circular cross-section along the folding lines;

[0010] Step 2: Assemble the elastic element onto the folding tube;

[0011] Step 3: Bond the flat sides of the folding tube together with double-sided tape, bond the silicone plate to the folding tube with silicone adhesive, punch a hole at one end of the folding tube, and bond the large silicone hose with a circular cross-section to the hole with silicone adhesive.

[0012] Moreover, in the first step and the second step, the folding method and the assembly method are respectively adjusted to obtain artificial muscle modules with four deformed configurations.

[0013] Moreover, the artificial muscle modules of the four deformation configurations include those that show a pure bending deformation configuration after being vertically folded and having the same number of elastic elements in each unit; those that show a non - continuous curvature bending deformation configuration after being vertically folded and having different numbers of elastic elements in each unit; those that show a helical deformation configuration after being obliquely folded and having the same number of elastic elements in each unit; and those that show a non - continuous curvature helical deformation configuration after being obliquely folded and having different numbers of elastic elements in each unit.

[0014] The advantages and positive effects of the present invention are:

[0015] The present invention constitutes a fold - assembled adjustable fluid - driven artificial muscle module through a D - shaped cross - section silicone tube, a small circular cross - section silicone hose, elastic elements, double - sided tape, a silicone plate, and silicone adhesive. The raw materials used in the artificial muscle module are commercial finished products. The manufacturing steps are simple, the process is clear, and the cost is low. At the same time, by simply adjusting the manufacturing process, different deformation configurations can be obtained, enabling large - range deformation, high output force, and high load - bearing capacity. After testing, the gripper assembled by the present invention can successfully grasp objects of different sizes, weights, and shapes, and can be applied to soft robots to complete difficult tasks in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a structural diagram of the present invention;

[0017] Figure 2 is a schematic diagram of the minimum repeating unit of the artificial muscle module of the present invention;

[0018] Figure 3 is a formation diagram of the assembly of the artificial muscle module of the present invention;

[0019] Figure 4 is a schematic diagram of the experiment in the specific implementation manner of the present invention.

[0020] Reference Signs Explanation:

[0021] 1 - D - shaped cross - section silicone tube, 2 - small circular cross - section silicone hose, 3 - elastic element, 4 - double - sided tape, 5 - silicone plate, 6 - silicone adhesive, 7 - large circular cross - section silicone hose. SPECIFIC IMPLEMENTATION MANNER

[0022] The following further details the present invention with reference to the drawings.

[0023] The fold - assembled adjustable fluid - driven artificial muscle module and its composition method are as Figure 1As shown in the figure, it includes a D-shaped cross-section silicone tube 1, a small round cross-section silicone hose 2, an elastic element 3, a double-sided tape 4, a silicone plate 5, a silicone adhesive 6, and a large round cross-section silicone hose 7. Among them, the D-shaped cross-section silicone tube is a silicone hose with a cross-section in the shape of the letter D. The small round cross-section silicone hose is arranged inside the D-shaped cross-section silicone tube along the axis direction of the D-shaped cross-section silicone tube to form a folding tube, forming a fluid driving layer. The convex side of the folding tube is close to the arc top of the D-shaped cross-section silicone tube, and the flat side of the folding tube is close to the flat bottom of the D-shaped cross-section silicone tube. The elastic unit is arranged on the convex side of the folding tube and nested at the adjacent creases on the convex side to form an extensible limiting layer. The double-sided tape is arranged on the flat side of the folding tube for bonding and fixing adjacent planes. The silicone plate is arranged on the flat side of the folding tube and bonded and fixed to the folding tube through the silicone adhesive as an inextensible limiting layer.

[0024] The folding tube is formed by repeatedly folding the combined structure of the D-shaped cross-section silicone tube and the small round cross-section silicone hose. A round hole is opened at the end of the external D-shaped cross-section silicone tube.

[0025] The round hole opened at the end of the D-shaped cross-section silicone tube is connected to the large round cross-section silicone hose through the silicone adhesive as a connecting pipeline for the fluid pressure source.

[0026] As Figure 2 shown, after filling the D-shaped cross-section silicone tube with pressurized fluid through the large round cross-section silicone hose (driving state), the chambers formed by the folding tubes expand and squeeze each other. Because the strain of the extensible limiting layer is much smaller than that of the inextensible limiting layer, the artificial muscle module will bend and deform towards the inextensible limiting layer direction, as Figure 2 .2 shows.

[0027] The regulation mechanism of the present invention includes: stiffness factor and folding factor.

[0028] Among them, the stiffness factor is: in the driving state, the magnitude of the bending deformation is characterized by the bending angle, and the elastic unit will limit the bending deformation. The number of elastic units nested in each unit of the folding tube can be regulated. More elastic units will increase the stiffness of the overall elastic unit and reduce the bending angle, while fewer elastic units will reduce the stiffness of the overall elastic unit and increase the bending angle, as Figure 2 .3 shows.

[0029] Among them, the folding factor is: in the driving state, the axis of the bending deformation is the straight line where the crease is located. The artificial muscle module obtained by vertical folding will produce two-dimensional in-plane bending, as Figure 2 .2 shows, and the artificially inclined folded muscle module will produce three-dimensional spatial spiral, as Figure 2 .4 shows.

[0030] The results of the above two regulation mechanisms are as follows: After vertical folding, a module with the same number of elastic elements in each unit exhibits a pure bending deformation configuration, as shown in Figure 2 .2; After vertical folding, a module with different numbers of elastic elements in each unit exhibits a non - continuous curvature bending deformation configuration, as shown in Figure 2 .3; After inclined folding, a module with the same number of elastic elements in each unit exhibits a helical deformation configuration, as shown in Figure 2 .4; After inclined folding, a module with different numbers of elastic elements in each unit exhibits a non - continuous curvature helical deformation configuration, as shown in Figure 2 .5.

[0031] By assembling artificial muscle modules, single - finger, double - finger, and triple - finger grippers with different configurations can be obtained, and these grippers can successfully grasp objects of different sizes, weights, and shapes.

[0032] As shown in Figure 3 , the specific implementation method of the present invention includes the following steps:

[0033] Step 1: Combine a silicone tube with a D - shaped cross - section and a small silicone hose with a circular cross - section, and draw equally - spaced scale marks on the surface of the silicone tube with a D - shaped cross - section. These marks are the locations of the subsequent creases. Repeat the folding of the silicone tube with a D - shaped cross - section along the crease line.

[0034] In this step, the folding operation can be regulated.

[0035] Method 1: Set the angle between the crease line and the silicone tube with a D - shaped cross - section to a right angle, that is, vertical folding.

[0036] Method 2: Set the angle between the crease line and the silicone tube with a D - shaped cross - section to an acute angle, that is, inclined folding.

[0037] Step 2: Assemble the elastic elements onto the folded tube. The elastic units are located on the planar side of the folded tube. In this step, the stiffness of the assembly operation can be regulated, that is, the number of elastic units can be changed.

[0038] Step 3: Bond the planar sides of the folded tubes together with double - sided tape, bond the silicone plate and the folded tube together with silicone adhesive, punch a hole at one end of the folded tube, and bond the large silicone hose with a circular cross - section and the hole together with silicone adhesive.

[0039] By regulating the folding method and the assembly method in the first and second steps respectively, four deformed configurations of the artificial muscle module can be obtained. After vertical folding, the module with the same number of elastic elements in each unit exhibits a pure bending deformed configuration; after vertical folding, the module with different numbers of elastic elements in each unit exhibits a non - continuous curvature bending deformed configuration; after inclined folding, the module with the same number of elastic elements in each unit exhibits a helical deformed configuration; after inclined folding, the module with different numbers of elastic elements in each unit exhibits a non - continuous curvature helical deformed configuration.

[0040] According to the above - mentioned fold - assembly - based adjustable fluid - driven artificial muscle module and its composition method, experiments are carried out to prove the effect of the present invention.

[0041] As Figure 4 shown, the proposed artificial muscle modules can be assembled into soft grippers with various configurations, and these grippers can achieve adaptive grasping of objects with different shapes, sizes, and weights. The two - finger gripper assembled based on the pure - bending artificial muscle module is suitable for grasping block - shaped and ring - shaped objects, including boxes, steel wool, packages, and copper strip coils, as Figure 4 .1 shows. This gripper can grasp a copper strip coil weighing up to 790.2 g. The three - finger gripper has a large movement range and high load - bearing capacity, endowing the ability to grasp large - volume and large - weight objects, especially for objects with geometric shapes of spheres and discs, as Figure 4 .2 shows. This gripper can pick up a standard - size basketball (diameter 24 cm) weighing 614.0 g and a wire coil (diameter 20 cm) weighing 1250.8 g. The high load - bearing capacity shown by the gripper demonstrates certain advantages compared with other soft grippers. The maximum output force of the traditional fluid - network - type actuator is only 1.4 N, and the maximum output force of the fiber - winding - type actuator can only reach 10 N. Compared with a commercially available soft gripper of similar size, such as the two - finger gripper of model SFG - FNM2 - N3052 from SRT Company, its load is only 600 g, and the maximum size of a single finger of the three - finger gripper of this company is only 88 mm, and the maximum diameter of the gripper base is 134 mm, which cannot effectively envelope large - volume objects and thus cannot achieve grasping.

[0042] Common soft grippers all have equal - curvature deformation and it is difficult to grasp objects with changing surface curvature. To solve this problem, the proposed non - continuous curvature artificial muscle modules can be assembled into a single - finger gripper, which can better adapt to the surface topography of the object. The deformed shape of this gripper shows a small curvature at the end and a large curvature at the base. This deformed shape can not only construct a large enough envelope space to accommodate the target object, but also perform well when grasping cylindrical objects, as Figure 4. As shown in Fig. 0.3. This gripper can grasp cylinders with various curvatures, such as from a hand sanitizer bottle to toilet paper, and cylinders with various weights, such as from a paper cup (12.9 g) to a thermos cup (252.5 g).

[0043] For slender structures, common grippers cannot adapt to the object shape, thus unable to achieve grasping. The spiral shape of the spiral pattern gripper proposed in the present invention enables closer contact with rod-shaped objects, thus achieving easy grasping, as Figure 4 . As shown in Fig. 0.4. In the test, the spiral pattern gripper can grasp a long ruler (65.4 g) and a heavy wrench weighing up to 678.8 g.

[0044] For objects with very irregular shapes, common grippers are also unable to achieve effective grasping, and may even damage the object being operated due to shape mismatch, especially for fragile and vulnerable objects, such as flowers. The non-continuous curvature spiral pattern gripper proposed in the present invention, as Figure 4 . As shown in Fig. 0.5, can well solve this problem. The end part of this gripper shows a large curvature to better establish contact with the lower part of the object, while the base shows a small curvature to form sufficient envelope space to wrap the upper part of the object. In actual tests, the spiral pattern gripper with non-continuous curvature can not only grasp fragile flowers (16.5 g), but also grasp hard pliers (356.4 g).

[0045] The test result data shows that: the operating pressure of the artificial muscle module in this embodiment is 0 - 150 kPa, the maximum bending angle is 360°, the maximum output force is 18.5 N, the maximum bearing capacity is 35.6 N, and the fastest response time is 250 ms.

[0046] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manners. Any other implementation manners obtained by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A controllable fluid-driven artificial muscle module based on folding and assembly, characterized in that: It includes a silicone tube with a D-shaped cross-section, a small silicone hose with a circular cross-section, an elastic element, double-sided tape, a silicone plate and silicone adhesive. Among them, the small silicone hose with a circular cross-section is arranged inside the silicone tube with a D-shaped cross-section along the axis direction of the silicone tube with a D-shaped cross-section to form a folding tube. The folding tube is formed by repeated folding of the combined structure of the silicone tube with a D-shaped cross-section and the small silicone hose with a circular cross-section to form a fluid-driven layer. The convex side of the folding tube is close to the arc top of the silicone tube with a D-shaped cross-section, and the flat side of the folding tube is close to the flat bottom of the silicone tube with a D-shaped cross-section. The elastic element is arranged on the convex side of the folding tube and nested at the adjacent creases on the convex side to form an extensible limiting layer. The double-sided tape is arranged on the flat side of the folding tube for bonding and fixing adjacent planes. The silicone plate is arranged on the flat side of the folding tube and bonded and fixed to the folding tube through silicone adhesive as an inextensible limiting layer. The number of elastic elements nested in each unit of the folding tube can be adjusted. More elastic elements will increase the stiffness of the overall elastic elements and reduce the bending angle, while fewer elastic elements will reduce the stiffness of the overall elastic elements and increase the bending angle.

2. The controllable fluid-driven artificial muscle module based on folding and assembly according to claim 1, characterized in that: A round hole is opened at the end of the silicone tube with a D-shaped cross-section.

3. The controllable fluid-driven artificial muscle module based on folding and assembly according to claim 2, characterized in that: The round hole opened at the end of the silicone tube with a D-shaped cross-section is connected to a large silicone hose with a circular cross-section through silicone adhesive as a connecting pipeline for the fluid pressure source.

4. A composition method of a controllable fluid-driven artificial muscle module based on folding and assembly according to any one of claims 1 to 3, characterized in that: It includes the following steps: Step 1: Place the small silicone hose with a circular cross-section inside the D-shaped silicone tube, draw equidistant scale marks on the surface of the D-shaped silicone tube, which are the positions of the subsequent creases, and repeatedly fold the combined structure of the D-shaped silicone tube and the small silicone hose with a circular cross-section along the fold line; Step 2: Assemble the elastic element onto the folding tube; Step 3: Bond the flat sides of the folding tube together with double-sided tape, bond the silicone plate to the folding tube with silicone adhesive, drill a round hole at one end of the folding tube, and bond the large silicone hose with a circular cross-section to the round hole with silicone adhesive.

5. The composition method of a controllable fluid-driven artificial muscle module based on folding and assembly according to claim 4, characterized in that: In steps 1 and 2, the folding method and the assembly method are respectively adjusted to obtain four deformed configurations of artificial muscle modules; the four deformed configurations of artificial muscle modules include modules that are vertically folded and have the same number of elastic elements in each unit, showing a pure bending deformed configuration; modules that are vertically folded and have different numbers of elastic elements in each unit show a non-continuous curvature bending deformed configuration; Modules that are inclined and folded and have the same number of elastic elements in each unit show a helical deformed configuration; The module that has undergone inclined folding and has a difference in the number of elastic elements within each unit exhibits a deformed configuration of a discontinuous curvature helix.

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