An integrated knitted glue-free composite robot flexible skin and a preparation method thereof

Abstract

The application discloses a kind of integrated knitted glue-free composite robot flexible skin and preparation method thereof.According to the three-dimensional shape of the part to be covered of robot, the knitted base with motion deformation area and non-motion protection area is formed by using computerized flat knitting machine integrated knitting, and the different mesh pore diameters of 0.2-0.45mm are formed by different loop length and loop density.The knitted base is arranged between the outer surface of mold core and the inner wall of cavity, forming the forming space with thickness of 0.5-0.8mm and 0.8-1.5mm respectively, injecting molten thermoplastic elastomer, so that it covers the outside of knitted base and enters the mesh and loop gap to cover part of knitted yarn, and does not penetrate to the inside surface;After pressure maintaining and cooling, the thermoplastic elastomer layer and the embedded part are formed, realizing glue-free mechanical embedding.The application can consider the deformation ability of active part of robot and the flexible protection of non-active part, and reduce the cutting, sewing and gluing composite process.

Description

Technical Field

[0001] This invention relates to the fields of robotic flexible skin, functional textile composite materials, and elastomer composite molding technology. Specifically, it relates to an integrated knitted glue-free composite robotic flexible skin and its preparation method. Background Technology

[0002] With the development of humanoid robots, bionic robotic hands, rehabilitation exoskeletons, and service robots, the outer surface of robots, in addition to serving the functions of shielding internal structures, buffering external collisions, and improving appearance, also needs to adapt to repetitive movements such as joint bending, twisting, and stretching. Existing flexible robot skins are often made of flexible materials such as silicone and thermoplastic elastomers, cast or injection molded as a whole. These materials can provide a relatively soft touch and a certain degree of cushioning, but due to the lack of fabric structure support, they are prone to insufficient shape retention, local tearing, or permanent deformation when subjected to continuous stretching, localized pulling, or repeated bending. The breathability of continuous elastomer layers is also usually poor, which is not conducive to heat dissipation when covering a large area of ​​the robot body. At the same time, the integrally molded skin often requires extensive repair or replacement after local wear.

[0003] To address the difficulty of repairing integral elastomer skin, existing technologies have proposed detachable and replaceable composite robot skin. Chinese invention patent CN115094642A discloses a method for preparing replaceable flexible robot skin. This method involves coating water-based polyurethane foam slurry onto release paper and bonding it to a four-way elastic base fabric. After drying, the slurry is cut and sewn according to the robot's shape. Heat treatment is then used to improve the stitching marks, and a water-based skin-feeling agent is sprayed onto the skin surface. This solution allows the robot skin to be replaced in a manner similar to putting on and taking off clothing, while also maintaining a certain level of tactile feel, abrasion resistance, and folding resistance. However, because this type of skin still requires processes such as coating, bonding, cutting, sewing, heating, and surface spraying, the production process involves multiple processing and positioning steps. The structural differences between the sewn area and the surrounding materials are also difficult to completely eliminate. Furthermore, under the long-term reciprocating motion of the robot joints, the connecting areas and different material layers may still be subjected to continuous tensile and shear forces.

[0004] Fabric materials possess good tensile strength, elongation, and breathability. Using knitted fabric to cover robot joints can reduce joint movement resistance to a certain extent. Chinese invention patent application CN120311389A discloses a fully formed knitted fabric for robot joint covering and its preparation method. This method uses a four-needle bed fully formed computer flat knitting machine to knit a fabric for covering shoulder, neck, or elbow joints, and sets up a main body, connecting part, stretching zone, and compression zone according to the joint shape, allowing the knitted fabric to conform to the robot joint and adapt to bending movements. This solution eliminates the need for subsequent cutting and sewing, and has certain advantages in three-dimensional shape adaptation and knitted structure zoning. However, the disclosure focuses on the knitted covering itself. While knitted fabric can provide elasticity, breathability, and appearance concealment, requirements for external impact cushioning, surface scratch resistance, anti-slip properties, and skin-like feel usually require supplementation with soft elastomer materials or other functional materials. How the knitted fabric and soft elastomer materials form a stable composite structure is not further explained in this solution.

[0005] Existing composites of knitted fabrics with soft elastomers such as TPE and silicone typically employ adhesives, hot melt adhesive films, or hot pressing. The fabrics may also require pre-cutting and sewing. Due to differences in elastic modulus, elongation, and resilience between the fabric and the elastomer, the bonding layer is susceptible to alternating shear stress during repeated bending of robot joints. This can lead to localized cracking, warping, or delamination after prolonged use. Furthermore, the adhesive layer increases the thickness and local stiffness of the composite material. Simultaneously, the requirements for softness, abrasion resistance, and cushioning capacity differ between robot joints, torso, and hands. Using a uniform knitted structure or elastomer layer of uniform thickness makes it difficult to simultaneously meet the movement and protection needs of each part. Therefore, there is a need for a flexible robot skin and its fabrication method that can adapt to the complex shape and movement states of different robot parts, while also considering structural stability, softness, surface protection, and processing efficiency. Summary of the Invention

[0006] One of the technical problems to be solved by the present invention is to provide a method for preparing an integrated knitted glue-free composite robot flexible skin, so as to solve the problems of existing robot flexible skins having many processing steps, insufficient reliability of interlayer bonding, difficulty in taking into account the performance of different areas, and poor adaptability to complex curved surfaces.

[0007] To overcome the shortcomings of the prior art, the present invention provides a method for preparing an integrated knitted adhesive-free composite robotic flexible skin, comprising the following steps: Based on the three-dimensional shape of the part to be covered by the robot, a computer flat knitting machine is used to knit an integral knitted base that is compatible with the part to be covered by the robot. The integral knitted base includes a motion deformation area and a non-motion protection area distributed in different regions. The mesh aperture of the motion deformation area is larger than that of the non-motion protection area. The mesh aperture of the integral knitted base is 0.2 to 0.45 mm. An integral knitted base is placed between the outer surface of the mold core and the inner wall of the cavity of the injection mold, so that the integral knitted base serves as part of the mold wall of the injection cavity. The molding space of the thermoplastic elastomer is defined by the outer surface of the mold core, the integral knitted base, and the inner wall of the cavity. The molding space thickness corresponding to the motion deformation zone is 0.5-0.8 mm, and the molding space thickness corresponding to the non-motion protection zone is 0.8-1.5 mm. Molten thermoplastic elastomer is injected into the molding space so that the thermoplastic elastomer covers the outer surface of the integral knitted substrate and enters the mesh and loop gaps from the outer surface to cover at least part of the knitted yarn. The thermoplastic elastomer enters the interior of the integral knitted substrate but does not penetrate to the inner surface of the integral knitted substrate. The thermoplastic elastomer is subjected to pressure holding and cooling and demolding, so that the thermoplastic elastomer inside the integrated knitted substrate is cooled to form an interlocking part. Through the interlocking part, the thermoplastic elastomer and the integrated knitted substrate form a glue-free mechanical interlocking structure, resulting in an integrated knitted glue-free composite robot flexible skin.

[0008] The method for preparing an integrated knitted, glue-free composite robot flexible skin provided by this invention has the following advantages: The method uses an integrated knitted substrate instead of traditional pieced fabric. In step S1, an overall knitting adapted to the robot's shape is completed, and different mesh structures are formed between the motion deformation zone and the non-motion protection zone, providing a foundation for subsequent injection molding of different areas. In step S2, by directly using the integrated knitted substrate as part of the injection cavity wall, the outer surface of the mold core, the integrated knitted substrate, and the inner wall of the cavity jointly define the molding space of the thermoplastic elastomer, eliminating the need for adhesive bonding. Simultaneously, the support of the mold core on the inner surface of the integrated knitted substrate restricts the molten thermoplastic... The thermoplastic elastomer continues to penetrate inwards; in step S3, the thermoplastic elastomer enters the mesh and loop gaps from the outside of the integrated knitted substrate, covering the knitted yarn and keeping the inner surface from being penetrated, so that the thermoplastic elastomer and the integrated knitted substrate form a mechanical interlocking rather than an adhesive connection, ensuring the stability of the bond while retaining the soft touch and elasticity of the inner side of the knitted layer; after the pressure holding and cooling are completed in step S4, the mechanical interlocking structure and the thickness design of different areas work together to keep the robot's moving parts with good bending flexibility, and the non-moving parts have good support and cushioning capacity, while reducing the problems of interlayer peeling, stress concentration and insufficient bonding of complex curved surfaces caused by traditional cutting, sewing and adhesive processes.

[0009] In one possible implementation, in step S1, the motion deformation area and the non-motion protection area are integrally knitted on the same integral knitting base. The motion deformation area is located in the area of ​​the integral knitting base corresponding to the robot's active part, and the non-motion protection area is located in the area of ​​the integral knitting base corresponding to the robot's non-active part.

[0010] In this embodiment, the moving deformation area and the non-moving protective area are integrally formed on the same integrated knitted base, eliminating the need for subsequent cutting, splicing and sewing. This reduces thickness changes and stress concentration at the splicing points, allowing the flexible skin to maintain a continuous transition between the robot's moving and non-moving parts. It also facilitates the continuous coverage of the entire knitted base by the thermoplastic elastomer during the subsequent injection molding process.

[0011] In one possible implementation, in step S1, the coil length and coil density of the moving deformation zone and the non-moving protection zone are different, so as to form different mesh apertures.

[0012] This embodiment further limits the coil length and coil density in different regions, so that the moving deformation area has a larger mesh aperture and the non-moving protection area has a smaller mesh aperture. The different pore structures correspond to the subsequent thermoplastic elastomers of different thicknesses, so that the moving area maintains good bending ability and the non-moving area has good support and flexible protection performance. The performance distribution of different regions is more in line with the usage requirements of various parts of the robot.

[0013] In one possible implementation, in step S2, the integral knitted base is disposed between the outer surface of the mold core and the inner wall of the cavity. The outer surface of the mold core is used to support the inner surface of the integral knitted base, and the inner wall of the cavity and the outer surface of the integral knitted base together define the molding space.

[0014] In this embodiment, the support of the mold core on the inner surface of the integrated knitted base can limit the thermoplastic elastomer from penetrating further inward. Together with the integrated knitted base and the inner wall of the cavity, a stable molding space is formed, so that the thermoplastic elastomer remains inside the knitted base after entering the mesh and loop gaps. This is conducive to forming a stable mechanical interlocking structure, while maintaining the integrity of the inner knitted surface.

[0015] In one possible implementation, in step S3, the thermoplastic elastomer is a SEBS-based thermoplastic elastomer, and the Shore A hardness of the SEBS-based thermoplastic elastomer is 5A to 30A.

[0016] This embodiment further employs SEBS-based thermoplastic elastomers with a Shore A hardness of 5A to 30A. While maintaining a soft touch and high deformation capacity, it can more easily penetrate the mesh and loop gaps of the knitted substrate, forming a covering on the knitted yarn, improving the mechanical interlocking effect, and giving the composite soft skin better bending and recovery properties.

[0017] In one possible implementation, in step S3, the injection temperature of the thermoplastic elastomer is 170–210°C.

[0018] This embodiment further limits the injection temperature based on the aforementioned materials, so that the thermoplastic elastomer has suitable fluidity. While ensuring that it can enter the mesh and loop gaps of the knitted substrate, it reduces excessive penetration caused by excessive flow, which is conducive to obtaining more stable composite quality and mechanical interlocking effect.

[0019] In one possible implementation, in step S4, the pressure holding and cooling time is 30 to 60 seconds.

[0020] In this embodiment, the holding and cooling time is controlled at 30 to 60 seconds, which allows the thermoplastic elastomer to be shaped inside the knitted substrate, reduces the shrinkage deformation generated during the cooling process, makes the formed mechanical interlocking structure more stable, and helps to improve the bonding strength of the composite layer.

[0021] Another technical problem that this invention aims to solve is to provide an integrated knitted glue-free composite flexible skin for robots, in order to address the issues of easy separation between layers, insufficient structural stability, and difficulty in simultaneously achieving flexibility and protective performance in different areas of existing flexible robot skins.

[0022] To overcome the shortcomings of the prior art, the present invention also provides an integrated knitted adhesive-free composite robotic flexible skin, comprising: An integral knitted base has an inner surface and an outer surface that are set opposite to each other; A thermoplastic elastomer layer is disposed on the outer surface of an integral knitted base; An interlocking portion integrally formed with the thermoplastic elastomer layer and extending from the thermoplastic elastomer layer into the interior of the integral knitted substrate; The interlocking portion enters the mesh and loop gaps of the integral knitted substrate and covers at least part of the knitted yarn, but does not extend to the inner surface of the integral knitted substrate. No adhesive layer is provided between the thermoplastic elastomer layer and the integral knitted substrate.

[0023] The integrated knitted adhesive-free composite robot flexible skin provided by the present invention has the following advantages: In the above-mentioned integrated knitted adhesive-free composite robot flexible skin of the present invention, a thermoplastic elastomer layer is disposed on the outside of the integrated knitted base, and the knitted yarn is wrapped through the mesh and loop gaps through the interlocking part, so that the two form a mechanical interlocking connection, and the composite can be achieved without relying on the adhesive layer; the interlocking part is kept inside the integrated knitted base and does not extend to the inner surface, which improves the overall stability of the composite structure while maintaining the softness of the inner side of the knitted layer, reduces the possibility of interlayer separation during long-term bending, and can take into account the flexibility, durability and appearance continuity of the robot flexible skin.

[0024] In one possible implementation, the integral knitted substrate includes a motion deformation zone and a non-motion protection zone, wherein the mesh aperture of the motion deformation zone is larger than that of the non-motion protection zone, and the thickness of the thermoplastic elastomer layer corresponding to the motion deformation zone is smaller than that of the thermoplastic elastomer layer corresponding to the non-motion protection zone.

[0025] In this embodiment, by using different mesh sizes and thermoplastic elastomer layers of different thicknesses to correspond to each other, the moving deformation area maintains high compliance, while the non-moving protection area has good buffering and flexible protection performance. Each area forms a differentiated performance distribution according to the robot's motion state, which is beneficial to take into account both overall motion performance and protection performance.

[0026] In one possible implementation, the integral knitted base is formed by weaving three layers of composite core-spun yarn, which includes a spandex core yarn, an inner elastic nylon layer covering the outside of the spandex core yarn, and an outer elastic nylon layer covering the outside of the inner elastic nylon layer.

[0027] In this embodiment, the three-layer composite core-spun yarn takes into account both elastic recovery capability and knitting stability, which can improve the dimensional stability of the integrated knitted substrate during injection molding and subsequent use. At the same time, it provides a more stable bonding foundation for the thermoplastic elastomer to cover the knitted yarn, which is conducive to maintaining the durability of the composite structure. Attached Figure Description

[0028] Figure 1 A schematic diagram of the interface cross-section structure of the flexible skin of an integrated knitted glue-free composite robot; Figure 2 A schematic diagram of the front and back loop interlocking structure of a single knitted base, wherein, Figure 2 (a) is a schematic diagram of the front loop structure of a one-piece knitted base. Figure 2 (b) Schematic diagram of the reverse coil structure of the integrated knitted base; Figure 3 A schematic diagram of the computerized flat knitting process and partial structure of a single-piece knitted base, wherein... Figure 3 (a) A computer-aided flat knitting process diagram for an integrated knitting base. Figure 3 (b) in accordance with Figure 3 (a) is a simulation diagram of the local tissue structure of the integral knitted base formed by the knitting process shown in the figure. Figure 4 A schematic diagram showing the distribution of the motion deformation zone and the non-motion protection zone on the robot body in a single-piece knitted substrate. Figure 4 (a) is a schematic diagram of the area distribution in the frontal view direction. Figure 4 (b) is a schematic diagram of the area distribution in the side view direction. Figure 4 (c) is a schematic diagram of the regional distribution in the rear view direction.

[0029] Explanation of reference numerals in the attached drawings: 1. One-piece knitted base; 11. Inner surface; 12. Outer surface; 2. Thermoplastic elastomer layer; 21. Fitting part. Detailed Implementation

[0030] First, those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0031] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0032] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] This invention provides a method for preparing an integrated knitted adhesive-free composite robotic flexible skin, comprising the following steps: S1: Based on the three-dimensional shape of the part to be covered by the robot, a computer flat knitting machine is used to knit an integral knitted base that is compatible with the part to be covered by the robot. The integral knitted base includes a motion deformation area and a non-motion protection area distributed in different regions. The mesh aperture of the motion deformation area is larger than that of the non-motion protection area. The mesh aperture of the integral knitted base is 0.2 to 0.45 mm. S2: An integral knitted base is placed between the outer surface of the mold core and the inner wall of the cavity of the injection mold, so that the integral knitted base serves as part of the mold wall of the injection cavity. The molding space of the thermoplastic elastomer is defined by the outer surface of the mold core, the integral knitted base, and the inner wall of the cavity. The molding space thickness corresponding to the motion deformation zone is 0.5-0.8 mm, and the molding space thickness corresponding to the non-motion protection zone is 0.8-1.5 mm. S3: Inject molten thermoplastic elastomer into the molding space, so that the thermoplastic elastomer covers the outer surface of the integral knitted substrate and enters the mesh and loop gaps from the outer surface to cover at least part of the knitted yarn. The thermoplastic elastomer enters the interior of the integral knitted substrate but does not penetrate to the inner surface of the integral knitted substrate. S4: The thermoplastic elastomer is held under pressure, cooled, and demolded, allowing the thermoplastic elastomer inside the integrated knitted substrate to cool and form an interlocking part. Through the interlocking part, the thermoplastic elastomer and the integrated knitted substrate form a glue-free mechanical interlocking structure, resulting in an integrated knitted glue-free composite robot flexible skin.

[0034] As a preferred embodiment, in step S1, the motion deformation area and the non-motion protection area are integrally knitted on the same integral knitting base. The motion deformation area is located in the area of ​​the integral knitting base corresponding to the robot's active part, and the non-motion protection area is located in the area of ​​the integral knitting base corresponding to the robot's non-active part.

[0035] As a preferred embodiment, in step S1, the coil length and coil density of the moving deformation zone and the non-moving protection zone are different, so as to form different mesh apertures.

[0036] As a preferred embodiment, in step S2, the integral knitted base is disposed between the outer surface of the mold core and the inner wall of the cavity. The outer surface of the mold core is used to support the inner surface of the integral knitted base, and the inner wall of the cavity and the outer surface of the integral knitted base together define the molding space.

[0037] As a preferred embodiment, in step S3, the thermoplastic elastomer is a SEBS-based thermoplastic elastomer, and the Shore A hardness of the SEBS-based thermoplastic elastomer is 5A to 30A.

[0038] As a preferred embodiment, in step S3, the injection temperature of the thermoplastic elastomer is 170–210°C.

[0039] As a preferred option, in step S4, the pressure holding and cooling time is 30 to 60 seconds.

[0040] The present invention also provides an integral knitted adhesive-free composite robotic flexible skin, comprising an integral knitted substrate, a thermoplastic elastomer layer, and an interlocking portion; the integral knitted substrate has an inner surface and an outer surface disposed opposite to each other, the thermoplastic elastomer layer is disposed on the outer surface of the integral knitted substrate, the interlocking portion is integrally formed with the thermoplastic elastomer layer and extends from the thermoplastic elastomer layer into the interior of the integral knitted substrate; the interlocking portion enters the mesh and loop gaps of the integral knitted substrate and covers at least a portion of the knitted yarn, and does not extend to the inner surface of the integral knitted substrate, and no adhesive layer is disposed between the thermoplastic elastomer layer and the integral knitted substrate.

[0041] As a preferred embodiment, the integrated knitted substrate includes a motion deformation zone and a non-motion protection zone. The mesh aperture of the motion deformation zone is larger than that of the non-motion protection zone, and the thickness of the thermoplastic elastomer layer corresponding to the motion deformation zone is smaller than that of the thermoplastic elastomer layer corresponding to the non-motion protection zone.

[0042] As a preferred embodiment, the integrated knitted base is formed by weaving three layers of composite core-spun yarn, which includes a spandex core yarn, an inner layer of elastic nylon covering the outside of the spandex core yarn, and an outer layer of elastic nylon covering the outside of the inner layer of elastic nylon.

[0043] This invention combines computer-controlled flat knitting with thermoplastic elastomer injection molding. It directly knits an integrated base to fit the three-dimensional shape of the robot's coverage area. The motion deformation zone and the non-motion protection zone are integrally formed on the same base, eliminating the need for cutting, splicing, and sewing. By adjusting the loop length and density in different areas, the motion deformation zone has a larger mesh aperture, while the non-motion protection zone has a smaller mesh aperture. Different thicknesses of thermoplastic elastomer molding spaces are formed in the injection mold. This results in a thinner thermoplastic elastomer layer for the motion deformation zone, facilitating stretching, bending, and rotation with the robot's joints, and a thicker layer for the non-motion protection zone, maintaining the robot's external coverage contour and providing flexible protection. During injection molding, the molten thermoplastic elastomer covers the outer surface of the integrated knitting base and penetrates the mesh and loop gaps to cover at least part of the coverage area. The knitted yarns are pressed and cooled to form an interlocking part that is integrally connected with the thermoplastic elastomer layer. This allows the thermoplastic elastomer layer and the integral knitted base to be connected by mechanical interlocking, eliminating the need for an adhesive layer between them. This reduces the risk of delamination and peeling caused by adhesive aging, repeated bending, or environmental changes. The integral knitted base provides softness, resilience, tensile strength, and the ability to conform to complex curved surfaces, while the thermoplastic elastomer layer provides cushioning, anti-slip properties, and surface protection. Furthermore, the thermoplastic elastomer does not penetrate to the inner surface of the integral knitted base, allowing the inner side of the flexible skin to retain the knitted loop structure and its soft touch. This invention also eliminates the cutting, sewing, gluing, laminating, and hot pressing processes in traditional composite processes. The main body of the flexible skin is prepared by knitting and in-mold injection molding. This allows for zoned adaptation of different parts of the robot, shortens the processing flow, reduces the use of seams and adhesive materials, and improves the overall appearance and structure of the robot's flexible skin.

[0044] The present invention will now be described in conjunction with the accompanying drawings and embodiments.

[0045] like Figure 2 As shown, the integrated knitting substrate has a process front coil structure and a process back coil structure. The coils in adjacent rows are interlocked to form a continuous knitting structure. Mesh openings and coil gaps are reserved between the coils to allow molten thermoplastic elastomer to enter. Figure 3 The diagram illustrates the computerized flat knitting process of an integrated knitting base and the local structure formed by this process. By changing the needle configuration, loop formation method, loop length, and knitting density of the computerized flat knitting machine, movement deformation zones and non-movement protection zones with different mesh apertures can be formed in the same integrated knitting base. The two zones are formed continuously during the knitting process without the need for cutting and sewing. Figure 4The distribution of motion deformation zones and non-motion protection zones on the robot body is shown. The areas corresponding to the robot's shoulder joint, elbow joint, wrist joint, waist, knee joint and ankle joint can be set as motion deformation zones, and the areas corresponding to the robot's chest, abdomen, back, upper arm, forearm, thigh and lower leg can be set as non-motion protection zones. Figure 4 The diagonally filled area in the diagram represents the non-motion protection zone, while the adjacent joint positions and areas that require bending, rotation, or extension represent the motion deformation zone.

[0046] Example 1 This embodiment provides an integrated knitted glue-free composite robotic flexible skin and its preparation method, including the following steps.

[0047] S1: Knitting of an integrated knit base Based on the three-dimensional shape of the robot's body, and referring to Figure 4 The knitting model is established based on the area distribution shown. The knitting model is divided into motion deformation area and non-motion protection area. The areas corresponding to the shoulder joint, elbow joint, wrist joint, waist, knee joint and ankle joint are divided into motion deformation area, and the areas corresponding to the chest, abdomen, back, upper arm, forearm, thigh and calf are divided into non-motion protection area.

[0048] Import the knitting pattern and zone knitting parameters into the computerized flat knitting machine, and then... Figure 3 The needle configuration and knitting process shown use a three-layer composite core-spun yarn to continuously knit an integrated knitting base that is adapted to the shape of the robot's body. The three-layer composite core-spun yarn includes a 70 denier spandex core yarn of model 162C, an inner layer of elastic nylon covering the outside of the spandex core yarn, and an outer layer of elastic nylon covering the outside of the inner layer of elastic nylon.

[0049] The motion deformation zone uses a large-coil, low-density plain weft knitting structure with a coil length of 5mm, a longitudinal density of 12 stitches / cm, and a transverse density of 15 rows / cm, forming a mesh with an aperture of 0.45mm. The non-motion protection zone uses a small-coil, high-density plain weft knitting structure with a coil length of 3mm, a longitudinal density of 20 stitches / cm, and a transverse density of 22 rows / cm, forming a mesh with an aperture of 0.20mm.

[0050] One-piece knitted base has Figure 2 The diagram shows the loop interlocking relationship between the front and back sides; by adjusting the loop formation parameters of the computer flat knitting machine at different needle positions and knitting rows, the motion deformation area and the non-motion protection area are knitted together on the same integrated knitting base, with a continuous transition between the two areas, without cutting, splicing, or sewing.

[0051] S2: In-mold setting of one-piece knitted base The integrated knitted base is fitted onto the outer surface of the injection mold core, which is adapted to the shape of the robot's body, with the inner surface of the integrated knitted base facing the outer surface of the mold core and the outer surface facing the inner wall of the cavity; the position of the integrated knitted base is adjusted so that... Figure 4 Each moving deformation zone and non-moving protection zone is aligned with the corresponding part on the mold core.

[0052] The integral knitted base is unfolded along the outer surface of the mold core. The edge of the integral knitted base is fixed to the positioning part around the periphery of the mold core, so that the integral knitted base maintains a predetermined position during mold closing and injection molding. After mold closing, the integral knitted base is located between the outer surface of the mold core and the inner wall of the cavity. The integral knitted base serves as part of the mold wall of the injection cavity. The outer surface of the mold core supports the inner surface of the integral knitted base. A molding space for accommodating molten thermoplastic elastomer is formed between the inner wall of the cavity and the outer surface of the integral knitted base.

[0053] The forming space thickness corresponding to the motion deformation zone is 0.5 mm, and the forming space thickness corresponding to the non-motion protection zone is 1.2 mm. The smaller forming space thickness in the motion deformation zone is used to reduce the bending resistance generated by the thermoplastic elastomer layer during joint movement, while the larger forming space thickness in the non-motion protection zone is used to maintain the external covering contour of the corresponding parts of the robot.

[0054] S3: In-situ injection molding of thermoplastic elastomers SEBS-based thermoplastic elastomer with a Shore A hardness of 8A was used as the injection molding material. The SEBS-based thermoplastic elastomer was heated to 170°C to form a molten state and injected into the molding space with an injection pressure of 40 bar.

[0055] After the molten thermoplastic elastomer enters the molding space, it flows and spreads along the outer surface of the integrated knitted substrate. Under the action of injection pressure, it enters the mesh and loop gaps from the outer surface. The thermoplastic elastomer that enters the interior of the integrated knitted substrate flows around some of the knitted yarns in the mesh edge and loop gaps and covers some of the knitted yarns.

[0056] The outer surface of the mold core forms a support on the inner surface of the integrated knitted substrate. By controlling the injection amount, melting temperature, injection pressure and molding space thickness of the thermoplastic elastomer, the thermoplastic elastomer enters the integrated knitted substrate to a depth of 1 / 4 to 1 / 3 of the thickness of the integrated knitted substrate, and the thermoplastic elastomer does not penetrate to the inner surface of the integrated knitted substrate.

[0057] S4: Pressure holding, cooling, and demolding After injection molding is completed, the mold is kept closed, and the thermoplastic elastomer in the molding space is held under pressure and cooled for 45 seconds. The thermoplastic elastomer located on the outer surface of the integrated knitted base is cooled to form a continuous thermoplastic elastomer layer, and the thermoplastic elastomer entering the gap between the mesh and the coil is cooled to form the interlocking part.

[0058] The interlocking part covers part of the knitted yarn and is integrally connected with the thermoplastic elastomer layer, so that the thermoplastic elastomer layer forms a glue-free mechanical interlocking structure with the integral knitted substrate through the interlocking part; after the pressure holding and cooling are completed, the mold is opened and the composite molded part is removed from the mold core to obtain the integral knitted glue-free composite robot flexible skin.

[0059] like Figure 1 As shown, the fabricated integrated knitted adhesive-free composite robot flexible skin includes an integrated knitted substrate, a thermoplastic elastomer layer formed on the outer surface of the integrated knitted substrate, and an interlocking portion extending from the thermoplastic elastomer layer into the interior of the integrated knitted substrate. The integrated knitted substrate has an inner surface and an outer surface that are disposed opposite to each other. The interlocking portion is integrally formed with the thermoplastic elastomer layer. The interlocking portion enters the mesh and loop gaps of the integrated knitted substrate and covers part of the knitted yarn, but does not extend to the inner surface of the integrated knitted substrate. No adhesive layer is provided between the thermoplastic elastomer layer and the integrated knitted substrate.

[0060] In this embodiment, the thickness of the integral knitted base is 0.6 mm, and the depth of the interlocking part entering the integral knitted base is 1 / 4 to 1 / 3 of the thickness of the integral knitted base; the interlocking part covers at least part of the knitted yarn on the side of the integral knitted base near the outer surface, and the inner surface of the integral knitted base does not form a continuous thermoplastic elastomer covering layer, and still retains the knitted loop structure.

[0061] In the prepared flexible skin, the motion deformation zone uses a larger mesh aperture and a smaller thermoplastic elastomer layer thickness, while the non-motion protection zone uses a smaller mesh aperture and a larger thermoplastic elastomer layer thickness. The motion deformation zone can stretch and bend with the robot's moving parts, while the non-motion protection zone is used to maintain the robot's external coverage contour and form flexible protection.

[0062] Example 2 This embodiment provides an integrated knitted glue-free composite flexible robot skin for humanoid robot arms and its preparation method. This embodiment is similar to Embodiment 1, except that the shape, regional distribution, weight, and molding space thickness of the integrated knitted substrate are different.

[0063] In step S1, a knitting model is established based on the three-dimensional shape of the humanoid robot arm. The areas corresponding to the shoulder, elbow, and wrist joints are divided into motion deformation zones, and the areas of the upper arm and forearm far from the joints are divided into non-motion protection zones. A three-layer composite core-spun yarn is continuously knitted using a computerized flat knitting machine to form an integrated knitting base that conforms to the shape of the robot arm. The weight of the integrated knitting base is 200g / m². 2 .

[0064] The motion deformation zone uses a large-coil, low-density plain weft knit weave, while the non-motion protection zone uses a small-coil, high-density plain weft knit weave; the motion deformation zone and the non-motion protection zone are arranged according to... Figure 2 and Figure 3 The coil structure and weaving method shown are continuously formed in the same integral knitting base.

[0065] In step S2, the integrated knitted base is fitted onto the outer surface of the core of the injection mold for the robot arm, so that the motion deformation areas corresponding to the shoulder joint, elbow joint and wrist joint are aligned with the joint positions on the core, and the non-motion protection areas corresponding to the upper arm and forearm are aligned with the corresponding positions on the core; the molding space thickness corresponding to the motion deformation area is 0.5mm, and the molding space thickness corresponding to the non-motion protection area is 0.8mm.

[0066] In step S3, SEBS-based thermoplastic elastomer with a Shore A hardness of 8A is used as the injection molding material, the injection temperature is 170°C, and the injection pressure is 40 bar. The molten thermoplastic elastomer covers the outer surface of the integrated knitted substrate and enters the mesh and loop gaps. The thermoplastic elastomer that enters the interior of the integrated knitted substrate covers part of the knitted yarn, but does not penetrate to the inner surface of the integrated knitted substrate.

[0067] In step S4, the thermoplastic elastomer is subjected to pressure cooling. The thermoplastic elastomer that enters the gap between the mesh and the coil cools to form an interlocking part. The thermoplastic elastomer layer forms a glue-free mechanical interlocking structure with the integral knitted substrate through the interlocking part. After demolding, a flexible skin that is adapted to the shape of the humanoid robot arm is obtained.

[0068] Flexible skin is installed on the outside of the humanoid robot arm, with the inner surface of the integrated knitted base facing the robot arm shell and the thermoplastic elastomer layer facing the outside of the robot; the motion deformation zones at the shoulder, elbow, and wrist joints expand and contract with joint rotation and bending, while the non-motion protection zones at the upper arm and forearm maintain the covered shape.

[0069] Example 3 This embodiment provides an integrated knitted adhesive-free composite flexible robot skin for robot torso and its preparation method. This embodiment is similar to Embodiment 1, except that the shape, regional distribution, weight, thermoplastic elastomer hardness, injection temperature, and molding space thickness of different regions of the integrated knitted substrate are different.

[0070] In step S1, a knitting model is established based on the three-dimensional shape of the robot's torso. The shoulder connection area and the waist bending area are divided into motion deformation areas, while the chest, abdomen, and back areas are divided into non-motion protection areas. A three-layer composite core-spun yarn is continuously knitted using a computerized flat knitting machine to form an integrated knitting base that conforms to the shape of the robot's torso. The weight of the integrated knitting base is 320 g / m². 2 .

[0071] The shoulder and waist curve areas use a plain weft knit weave with larger loop lengths and lower knit density, while the chest, abdomen, and back areas use a plain weft knit weave with smaller loop lengths and higher knit density; different areas use... Figure 2 The coil nesting structure shown is used, and through Figure 3 The computer-controlled flat knitting process shown is continuously formed.

[0072] In step S2, the integrated knitted base is fitted onto the outer surface of the core of the robot torso injection mold, so that the shoulder connection area, waist bending area, chest, abdomen and back are aligned with the corresponding parts on the core; the molding space thickness corresponding to the shoulder connection area and waist bending area is 0.8mm, and the molding space thickness corresponding to the chest, abdomen and back is 1.2mm.

[0073] In step S3, SEBS-based thermoplastic elastomer with a Shore A hardness of 10A is used as the injection molding material. The SEBS-based thermoplastic elastomer is heated to 190°C to form a molten state and injected into the molding space. The molten thermoplastic elastomer covers the outer surface of the integral knitted substrate and enters the mesh and loop gaps to cover part of the knitted yarn. The thermoplastic elastomer does not penetrate to the inner surface of the integral knitted substrate.

[0074] In step S4, the thermoplastic elastomer is subjected to pressure holding and cooling. After cooling, the thermoplastic elastomer forms a thermoplastic elastomer layer on the outside of the integrated knitted substrate and an interlocking part integrally connected with the thermoplastic elastomer layer is formed inside the integrated knitted substrate. After demolding, an integrated knitted glue-free composite robot flexible skin that is adapted to the shape of the robot torso is obtained.

[0075] In the flexible skin prepared in this embodiment, the shoulder connection area and the waist bending area can bend with the movement of the robot's torso, and the chest, abdomen and back are continuously covered by a thermoplastic elastomer layer with a thickness of 1.2 mm; the inner surface of the integral knitted base maintains the knitted loop structure, and no adhesive layer is provided between the thermoplastic elastomer layer and the integral knitted base.

[0076] Example 4 This embodiment provides an application of an integrated knitted adhesive-free composite robot flexible skin, which includes installing the robot arm flexible skin obtained in Embodiment 2 onto the outside of a humanoid robot arm, and installing the robot torso flexible skin obtained in Embodiment 3 onto the outside of a humanoid robot torso.

[0077] During installation, the inner surface of the integrated knitted base faces the robot housing, and the thermoplastic elastomer layer faces the outside of the robot; according to Figure 4The area distribution shown corresponds to the movement deformation area for the shoulder joint, elbow joint, wrist joint, shoulder connection area, and waist bending area, respectively, and the main areas of the chest, abdomen, back, upper arm, and forearm correspond to the non-movement protection area.

[0078] The robot is driven to rotate its shoulder, flex and extend its elbow, rotate its wrist, and bend its waist. The knitted coils in the motion deformation zone stretch and contract with the robot's movement, and the thinner thermoplastic elastomer layer bends with the integral knitted base. The non-motion protection zone maintains the robot's external coverage contour through a higher knitting density and a thicker thermoplastic elastomer layer.

[0079] After the robot stops moving, the integrated knitted base recovers under the elastic action of the three-layer composite core-spun yarn, and the thermoplastic elastomer layer returns to a state that matches the shape of the robot along with the integrated knitted base; the thermoplastic elastomer layer and the integrated knitted base are connected through the interlocking part, and the inner surface of the flexible skin still retains the knitted structure.

[0080] Performance Characterization To analyze the properties of TPE materials with different hardness used to form thermoplastic elastomer layers under the molding and cooling state, SEBS-based thermoplastic elastomer with a Shore A hardness of 5A and medium-hardness TPE materials were selected, and TPE molding samples were prepared respectively. The tensile properties, tear properties and surface hardness of the molding samples were then tested.

[0081] Each test specimen was individually molded from TPE material, without an integral knitted substrate. The test results were used to characterize the tensile deformation capacity, tear resistance and surface hardness of the TPE material constituting the outer thermoplastic elastomer layer of the flexible skin of the integral knitted glue-free composite robot in the molding and cooling state. The application methods of TPE materials with different hardness were analyzed in combination with the mesh pore size and molding space thickness of the motion deformation zone and the non-motion protection zone.

[0082] Performance Test 1: Tensile Properties of 5A Thermoplastic Elastomer Molded Specimens Tensile specimens were prepared from SEBS-based thermoplastic elastomers with a Shore A hardness of 5A, and tensile properties were tested according to the method specified in GB / T 528. The specimens included type 2 specimens and type 1 specimens.

[0083] Type 2 specimens consisted of 5 valid specimens, each with a thickness of 1.76 mm, a width of 4 mm, and an initial gauge length of 25 mm. Type 1 specimens consisted of 5 valid specimens, each with a thickness of 1.76 mm, a width of 6.22 mm, and an initial gauge length of 25 mm. One Type 1 specimen failed to break during testing because it exceeded the equipment's range; this was not included in the statistical results.

[0084] Table 1. Tensile property test results of 5A thermoplastic elastomer molded specimens As shown in Table 1, the tensile strengths of the five Type 2 specimens were 1.57 MPa, 1.48 MPa, 1.51 MPa, 1.43 MPa and 1.59 MPa, respectively, with an average tensile strength of 1.516 MPa; the tensile fracture strains were 583.35%, 506.21%, 605.07%, 508.61% and 466.99%, respectively, with an average tensile fracture strain of 534.05%.

[0085] The tensile strengths of the five Type 1 specimens were 0.732 MPa, 0.780 MPa, 0.778 MPa, 0.859 MPa and 0.819 MPa, respectively, with an average tensile strength of 0.794 MPa; the tensile fracture strains were 654.34%, 627.09%, 568.38%, 627.88% and 708.85%, respectively, with an average tensile fracture strain of 637.31%.

[0086] Test results show that SEBS-based thermoplastic elastomers with a Shore A hardness of 5A still have a large tensile deformation capacity after molding and cooling. The average tensile fracture strains of type 2 and type 1 specimens are 534.05% and 637.31%, respectively. In the flexible skin of an integrated knitted adhesive-free composite robot, this type of low-hardness TPE material can be matched with the large mesh size and small molding space thickness of the motion deformation zone, so that the formed thermoplastic elastomer layer can be stretched and bent with the moving parts of the robot.

[0087] Performance Test 2: Tear Resistance Test of 5A Thermoplastic Elastomer Molded Specimens Tear test specimens were prepared using SEBS-based thermoplastic elastomers with a Shore A hardness of 5A, and the tear performance was tested according to the method specified in GB / T 529.

[0088] This test included 5 valid samples, each with a thickness of 1.78 mm, a width of 6 mm, and an original gauge length of 25 mm; one sample did not obtain a valid test result and was not included in the results statistics.

[0089] Table 2. Tear performance test results of 5A thermoplastic elastomer molded specimens As shown in Table 2, the tensile fracture strains of the five valid specimens were 470.18%, 573.30%, 455.46%, 499.62%, and 443.55%, respectively, with an average tensile fracture strain of 488.42%. The maximum forces were 14.07 N, 13.76 N, 13.57 N, 13.87 N, and 14.60 N, respectively, with an average maximum force of 13.97 N. The tear strengths were 7.9 kN / m, 7.7 kN / m, 7.6 kN / m, 7.8 kN / m, and 8.2 kN / m, respectively, with an average tear strength of 7.84 kN / m.

[0090] Test results show that 5A thermoplastic elastomer has a large tensile deformation capacity after molding and cooling, and maintains a certain tear resistance. This property can provide a basis for maintaining the material continuity of the thinner thermoplastic elastomer layer in the motion deformation zone under repeated stretching, bending and local stress.

[0091] Performance Test 3: Tensile Properties of Medium-Hardness TPE Molded Specimens Select another TPE material of different hardness grades to prepare molded samples, and conduct tensile property tests according to the method specified in ISO 37-2017 at a test speed of 500 mm / min. Cut 5 specimens along the transverse and longitudinal directions of the TPE molded sample, and test the tensile strength, elongation at break, tensile stress at 100% strain and tensile stress at 300% strain of each specimen.

[0092] Table 3 Tensile property test results of TPE molded specimens of another hardness grade As shown in Table 3, the tensile strengths of the transverse specimens were 1.4212 MPa, 1.3807 MPa, 1.8630 MPa, 1.5992 MPa and 1.2964 MPa, respectively, with an average tensile strength of 1.5121 MPa; the tensile strengths of the longitudinal specimens were 2.3438 MPa, 2.5116 MPa, 1.8200 MPa, 1.7110 MPa and 1.9082 MPa, respectively, with an average tensile strength of 2.0589 MPa.

[0093] The elongation at break of the transverse specimens were 1226.1%, 1156.6%, 1367.6%, 1439.8%, and 1064.9%, respectively, with an average elongation at break of 1251.0%; the elongation at break of the longitudinal specimens were 1567.7%, 1928.7%, 1367.7%, 1228.7%, and 1470.4%, respectively, with an average elongation at break of 1512.6%.

[0094] At 100% strain, the tensile stresses of the transverse specimens were 0.2240 MPa, 0.1321 MPa, 0.2046 MPa, 0.1955 MPa, and 0.2098 MPa, with an average value of 0.1932 MPa; the tensile stresses of the longitudinal specimens were 0.1935 MPa, 0.2074 MPa, 0.1837 MPa, 0.2115 MPa, and 0.1567 MPa, with an average value of 0.1906 MPa.

[0095] At 300% strain, the tensile stresses of the transverse specimens were 0.4304 MPa, 0.4126 MPa, 0.4154 MPa, 0.3745 MPa, and 0.4408 MPa, with an average value of 0.4147 MPa; the tensile stresses of the longitudinal specimens were 0.3848 MPa, 0.4053 MPa, 0.3855 MPa, 0.4071 MPa, and 0.3559 MPa, with an average value of 0.3877 MPa.

[0096] Test results show that the TPE material has a large tensile deformation capacity in both the transverse and longitudinal directions after molding and cooling, with average elongation at break of 1251.0% and 1512.6% in the transverse and longitudinal directions, respectively. Under 100% strain and 300% strain conditions, the molded sample maintains relatively low tensile stress, and can maintain its stretching and bending capacity after forming a thermoplastic elastomer layer of a certain thickness.

[0097] Performance Test 4: Surface Hardness Test of Medium Hardness TPE Molded Samples The Shore A hardness test was performed on the medium-hardness TPE molded sample used in performance test 3. The test was carried out according to the method specified in ISO 868-2003. A total of 5 groups of samples were selected, and each group of samples was tested 5 times.

[0098] Table 4. Shore A hardness test results of medium-hardness TPE molded specimens As shown in Table 4, the test values ​​of the first group of samples were 16.6, 16.4, 16.0, 16.3, and 17.0, with an average of 16.5; the test values ​​of the second group of samples were 17.4, 17.1, 16.8, 16.7, and 17.2, with an average of 17.0; the test values ​​of the third group of samples were 18.0, 17.5, 17.3, 17.9, and 18.1, with an average of 17.8; the test values ​​of the fourth group of samples were 16.2, 16.7, 16.1, 17.2, and 16.6, with an average of 16.6; and the test values ​​of the fifth group of samples were 16.9, 17.1, 17.5, 16.4, and 16.8, with an average of 16.9.

[0099] The average hardness of the five groups of samples ranged from 16.5A to 17.8A, and the total average value of the 25 tests was 16.96A. All test values ​​ranged from 16.0A to 18.1A, indicating that the medium-hardness TPE molded sample has a relatively stable surface hardness.

[0100] Based on the tensile results of performance test 3, the TPE material of this hardness level maintains a large tensile deformation capacity while having a relatively stable surface hardness. It can be used to form a relatively thick thermoplastic elastomer layer, providing a material performance basis for maintaining the external coverage contour of the non-moving protective area and adapting to the overall movement of the robot.

[0101] Performance characterization of one-piece knitted base To analyze the performance of the fabric used to form an integral knitted base under stretching, tearing, friction and repeated deformation conditions, the fabric was tested for tensile properties, tearing properties, abrasion resistance and elastic recovery rate.

[0102] Performance Test 5: Tensile Properties of Fabric The tensile properties of the fabric were tested according to the strip method specified in GB / T 3923.1—2013. Three samples were selected in the transverse and longitudinal directions respectively, and the breaking strength and elongation at break of each sample were tested. The test results are shown in Table 5.

[0103] Table 5. Tensile property test results of fabrics As shown in Table 5, the average breaking strength of the transverse samples of the fabric was 170 N, and the average elongation at break was 564%; the average breaking strength of the longitudinal samples was 190 N, and the average elongation at break was 559%. The test results indicate that the fabric has a large tensile deformation capacity in both the transverse and longitudinal directions, which can provide a material basis for the integral knitted substrate to stretch and bend with the robot joints and other moving parts.

[0104] Performance Test 6: Tear Performance Test of Fabric The tear performance of the fabric was tested according to the trapezoidal method specified in GB / T 3917.3—2025. Five samples were selected in both the transverse and longitudinal directions. The test results are shown in Table 6.

[0105] Table 6. Test results of tear performance of fabrics As shown in Table 6, the average tear strength of the fabric in the transverse and longitudinal directions is 95.75 N and 89.13 N, respectively, indicating that the fabric can withstand certain local tearing in both directions, which is beneficial for the integrated knitted base to maintain structural continuity during robot movement and local stress.

[0106] Performance Test 7: Abrasion Resistance Test of Fabric According to the method specified in GB / T 21196.2—2007, the fabric was subjected to 5000 abrasion tests using a Martindale abrasion tester, and a total of 3 samples were selected.

[0107] Table 7. Test results of abrasion resistance of fabric materials After completing 5,000 Martindale abrasion tests, the support material in all three samples was not visible and did not crack or loosen. This indicates that the fabric can maintain a relatively intact surface structure under repeated friction, which can provide a basis for the abrasion resistance of the integrated knitted base during use.

[0108] Performance Test 8: Elastic Recovery Rate Test of Fabric The elastic recovery rate of the fabric was determined according to the method specified in FZ / T 70006—2022, using a constant elongation of 50%. Three samples were selected along the transverse and longitudinal directions respectively. The test results are shown in Table 8.

[0109] Table 8. Test results of elastic recovery rate of fabric materials As shown in Table 8, the average elastic recovery rates of the fabric in the transverse and longitudinal directions are 91.1% and 91.7%, respectively, indicating that the fabric can recover to its near-original state after being stretched by 50% and the external force is removed. This property is beneficial for the integrated knitted base to recover its original shape after stretching and bending with the movement of the robot, reducing relaxation and residual deformation during long-term use.

[0110] In summary, performance tests 1-4 characterized the properties of TPE materials with a Shore A hardness of 5A and medium-hardness TPE materials under the molding and cooling state. Both TPE materials maintained a large tensile deformation capacity. Among them, the 5A TPE material also showed a certain tear resistance. The measured Shore A hardness of the medium-hardness TPE molded samples ranged from 16.0A to 18.1A, with an average value of 16.96A from 25 tests. While maintaining tensile deformation capacity, it also had relatively stable surface hardness, providing a material performance reference for selecting TPE materials with appropriate hardness grades according to the overall movement range and protection requirements of different robot products or different parts to be covered.

[0111] Performance tests were conducted on pairs of fabrics used to form the integrated knitted base for tensile, tear, abrasion, and elastic recovery performance tests. The average elongation at break of the fabrics in the transverse and longitudinal directions was 564% and 559%, respectively, and the average tear strength was 95.75 N and 89.13 N, respectively. After 5000 cycles of Martindale abrasion resistance testing, none of the three samples broke or loosened. The average elastic recovery rates in the transverse and longitudinal directions were 91.1% and 91.7%, respectively. These results indicate that the fabric has a large elongation capacity in different directions and can maintain good structural integrity and recovery capacity after local tearing, repeated friction, and stretching deformation. This provides a material basis for the integrated knitted base to stretch and bend with the robot's moving parts and restore its original shape after the external force is removed.

[0112] The test results above show that the integrated knitted substrate and the thermoplastic elastomer layer complement each other in terms of performance. The integrated knitted substrate mainly provides tensile load-bearing capacity, tear resistance, abrasion resistance, and elastic recovery, while the thermoplastic elastomer layer provides soft outer coverage, tensile deformation, and surface protection. The test results of TPE materials with different hardnesses illustrate that the appropriate hardness grade of TPE material can be selected according to the overall movement range, coverage contour, and protection requirements of the robot's coverage area. The same TPE material with the same hardness grade is used in the injection molding process for the same integrated knitted glue-free composite robot flexible skin. The performance difference between the motion deformation zone and the non-motion protection zone is mainly achieved through the partitioning of the coil structure and mesh aperture of the integrated knitted substrate, as well as the thickness of the thermoplastic elastomer layer. The motion deformation zone uses a larger mesh aperture and a smaller thermoplastic elastomer layer thickness to accommodate the extension and bending of the robot's joints and other moving parts, while the non-motion protection zone uses a smaller mesh aperture and a larger thermoplastic elastomer layer thickness to maintain the robot's external coverage contour and provide flexible protection.

[0113] In the description of the embodiments of the present invention, it should be noted that the terms "inner" and "outer", etc., indicating the direction or positional relationship, are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention.

[0114] The above embodiments further demonstrate that the present invention can design the coil structure, mesh aperture, and thermoplastic elastomer layer thickness of the integrated knitted substrate in sections according to the shape and movement mode of different parts of the robot. This allows moving parts such as joints to have good extension and bending adaptability, while also enabling non-moving parts such as the torso to maintain a relatively stable covering contour. During injection molding, the molten thermoplastic elastomer enters the mesh and coil gaps of the integrated knitted substrate and covers part of the knitted yarn. After cooling, it forms an interlocking part that is integrated with the thermoplastic elastomer layer, thus completing the connection between the integrated knitted substrate and the thermoplastic elastomer layer without the need for an adhesive layer, while preserving the original knitted structure on the inner side of the integrated knitted substrate. Related performance tests also further illustrate that TPE materials with a Shore A hardness of 5A and medium-hardness TPE materials still have significant tensile deformation capacity after molding and cooling. Among them, 5A TPE also has a certain tear resistance, while medium-hardness TPE can provide relatively stable surface hardness while maintaining tensile properties. This provides a reference for selecting thermoplastic elastomer materials with appropriate hardness grades for different robot products or different parts to be covered. It can be seen that the present invention, through the combination of knitted tissue partitioning, molding thickness partitioning, and glue-free mechanical interlocking, enables the produced robotic flexible skin to take into account both the compliant deformation of active parts and the coverage and protection of inactive parts.

[0115] In the description of this invention, the terms "one embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, those skilled in the art can combine and integrate different embodiments or examples described in this specification, as well as features of different embodiments or examples, to describe specific features, structures, materials, or situations.

[0116] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an integrated knitted, glue-free composite robotic flexible skin, characterized in that, Includes the following steps: S1: Based on the three-dimensional shape of the part of the robot to be covered, a computer flat knitting machine is used to knit an integral knitted base that is compatible with the part of the robot to be covered. The integral knitted base includes a motion deformation area and a non-motion protection area distributed in different regions. The mesh aperture of the motion deformation area is larger than that of the non-motion protection area. The mesh aperture of the integral knitted base is 0.2 to 0.45 mm. S2: The integral knitted substrate is disposed between the outer surface of the mold core and the inner wall of the cavity of the injection mold, so that the integral knitted substrate serves as part of the mold wall of the injection cavity. The outer surface of the mold core, the integral knitted substrate, and the inner wall of the cavity together define the molding space of the thermoplastic elastomer. The molding space thickness corresponding to the moving deformation zone is 0.5-0.8 mm, and the molding space thickness corresponding to the non-moving protection zone is 0.8-1.5 mm. S3: Inject molten thermoplastic elastomer into the molding space, so that the thermoplastic elastomer covers the outer surface of the integral knitted substrate and enters the mesh and loop gaps from the outer surface to cover at least part of the knitted yarn. The thermoplastic elastomer enters the interior of the integral knitted substrate but does not penetrate to the inner surface of the integral knitted substrate. S4: The thermoplastic elastomer is subjected to pressure cooling and demolding, so that the thermoplastic elastomer that has entered the interior of the integrated knitted substrate is cooled to form an interlocking part, and the thermoplastic elastomer and the integrated knitted substrate are formed into a glue-free mechanical interlocking structure through the interlocking part, thereby obtaining the integrated knitted glue-free composite robot flexible skin.

2. The method for preparing the integrated knitted glue-free composite robotic flexible skin according to claim 1, characterized in that, In step S1, the motion deformation area and the non-motion protection area are integrally knitted on the same integral knitting base. The motion deformation area is located in the area of ​​the integral knitting base corresponding to the robot's active part, and the non-motion protection area is located in the area of ​​the integral knitting base corresponding to the robot's non-active part.

3. The method for preparing the integrated knitted glue-free composite robotic flexible skin according to claim 1, characterized in that, In step S1, the coil length and coil density of the moving deformation zone and the non-moving protection zone are different, so as to form different mesh apertures.

4. The method for preparing the integrated knitted glue-free composite robotic flexible skin according to claim 1, characterized in that, In step S2, the integral knitted base is disposed between the outer surface of the mold core and the inner wall of the cavity. The outer surface of the mold core is used to support the inner surface of the integral knitted base, and the inner wall of the cavity and the outer surface of the integral knitted base together define the molding space.

5. The method for preparing the integrated knitted glue-free composite robotic flexible skin according to claim 1, characterized in that, In step S3, the thermoplastic elastomer is a SEBS-based thermoplastic elastomer, and the Shore A hardness of the SEBS-based thermoplastic elastomer is 5A to 30A.

6. The method for preparing the integrated knitted glue-free composite robotic flexible skin according to claim 5, characterized in that, In step S3, the injection temperature of the thermoplastic elastomer is 170–210°C.

7. The method for preparing the integrated knitted glue-free composite robotic flexible skin according to claim 1, characterized in that, In step S4, the pressure holding and cooling time is 30 to 60 seconds.

8. A one-piece knitted adhesive-free composite robotic flexible skin prepared by the preparation method according to any one of claims 1 to 7, characterized in that, include: An integral knitted base has an inner surface and an outer surface that are set opposite to each other; A thermoplastic elastomer layer disposed on the outer surface of the integral knitted substrate; An interlocking portion integrally formed with the thermoplastic elastomer layer and extending from the thermoplastic elastomer layer into the interior of the integral knitted substrate; The fitting portion enters the mesh and loop gaps of the integral knitted substrate and covers at least part of the knitted yarn, but does not extend to the inner surface of the integral knitted substrate. No adhesive layer is provided between the thermoplastic elastomer layer and the integral knitted substrate.

9. The integrated knitted adhesive-free composite robotic flexible skin according to claim 8, characterized in that, The integrated knitted substrate includes a motion deformation zone and a non-motion protection zone. The mesh aperture of the motion deformation zone is larger than that of the non-motion protection zone, and the thickness of the thermoplastic elastomer layer corresponding to the motion deformation zone is smaller than that of the thermoplastic elastomer layer corresponding to the non-motion protection zone.

10. The integrated knitted adhesive-free composite robotic flexible skin according to claim 8, characterized in that, The integrated knitted base is woven from three layers of composite core-spun yarn, which includes a spandex core yarn, an inner layer of elastic nylon covering the outside of the spandex core yarn, and an outer layer of elastic nylon covering the outside of the inner layer of elastic nylon.

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