Self-sensing flexible pneumatic hand claw and preparation method

Abstract

The application discloses a self-sensing flexible pneumatic hand claw and a preparation method. The hand claw comprises a plurality of flexible fingers, each of the flexible fingers comprises a finger main body, a gas chamber array is arranged on one side of the finger main body and along the length direction of the finger main body, and a plurality of flexible sensors for force sensing are arranged on the other side of the finger main body and along the length direction of the finger main body, wherein the gas chamber array comprises a plurality of gas chambers, and the gas chambers are communicated with each other, and in working, the flexible fingers are driven to bend by being inflated in the gas chambers. The gas chamber array can be inflated (positive pressure), so that the flexible fingers can bend inward, the hand claw clamps the articles, the flexible sensors arranged in the hand claw can feedback the clamping pressure, and the hand claw can be applied to object grabbing.

Description

Technical Field

[0001] This invention belongs to the field of mechanical structure design, and relates to the design of flexible robot structures, specifically to a one-step self-sensing flexible pneumatic gripper and its preparation method. Background Technology

[0002] Human hand behaviors include strong grasping, dexterous manipulation, and communicative gestures. These activities are primarily achieved through the complex biomechanical structure and neural control of the human hand. This necessitates that the developed robotic hand possess multiple degrees of freedom in its structure and a certain degree of flexibility in its movements.

[0003] With the development of artificial intelligence technology, automation and intelligence have become technological trends in engineering and industry. The development of new robots is inseparable from structural design, especially the mechanical grippers that serve as the robot's hands. Current design concepts emphasize anthropomorphism and flexibility. Besides mimicking the dexterity of human hands, it also needs to mimic the tactile perception of human skin.

[0004] With the development of flexible sensors, a large number of studies on "electronic skin" have emerged in academia, making self-sensing robotic grippers a possibility. For example, Chen Li et al. disclosed in Chinese invention patent CN116494297A, "Flexible tactile sensing system for robotic grippers and its fabrication method," which consists of a multi-filament microstructured flexible pressure sensor for tactile perception and a photofilament ablation graphene / silicon solar cell for system power. This system can endow robotic grippers with tactile sensing capabilities, and the micro-nano structure of its multi-filament microstructured flexible pressure sensor can effectively improve the sensing performance of the device. Similarly, Chen Tao et al. disclosed in Chinese Invention Publication Patent CN115351806A a “Pneumatic Soft Grip Sensing Device”, which includes: a support member; a flexible gripping mechanism, the flexible gripping mechanism including at least two flexible grippers, the at least two flexible grippers being arranged circumferentially on the support member, each flexible gripper including a retractable airbag, a connecting mechanism and a flexible plate connected to the connecting mechanism, the retractable airbag being hollow and elongated, the retractable airbag including a closed end, an open end and an airbag body connecting the closed end and the open end, the airbag body including at least two airbag bodies and a node formed between adjacent airbag bodies, the connecting mechanism being connected to the node, the closed end and the open end; and a sensing mechanism, the sensing mechanism including at least two sensors, the sensors being disposed on the inner side of the corresponding flexible plate. This technical solution achieves the inflating and deflating of the retractable airbag by fixing the open end, the closed end, the node portion, and the flexible plate, thereby changing the bending direction of the airbag and thus grasping the object. It also realizes the sensing design of the flexible gripper. However, the above-mentioned related patent solutions mainly focus on the design of the sensing system, and the design and fabrication of the sensor are independent of the gripper, which has two shortcomings: (1) it fails to conduct optimization research on the structural design of the sensor; (2) it fails to propose a convenient process for the simultaneous fabrication of the gripper and the sensor. Summary of the Invention

[0005] In order to at least address one of the shortcomings of the existing technology, the present invention provides a one-step molding self-sensing flexible pneumatic gripper that can realize the integrated design of flexible gripper and flexible sensor, and has the advantages of "drive-sensing" integration.

[0006] To achieve the objective of this invention, a self-sensing flexible pneumatic gripper is provided, comprising multiple flexible fingers. Each flexible finger includes a finger body. A gas chamber array is arranged on one side of the finger body along its length, and multiple flexible sensors for force sensing are arranged on the other side along its length. The gas chamber array includes multiple gas chambers, which are interconnected. During operation, the flexible finger is driven to bend by inflating the gas chambers.

[0007] Using the above technical solution, gas can be filled into the gas chamber array (positive pressure), which allows the flexible fingers to bend inward and the gripper to hold the object. The flexible sensor installed in the gripper can provide feedback on the gripping pressure.

[0008] A further improvement to the present invention is that the self-sensing flexible pneumatic gripper includes three flexible fingers.

[0009] In a further improvement of the present invention, the gas chamber array includes multiple gas chambers, and an external reinforcing support structure is provided between adjacent gas chambers.

[0010] In a further improvement to the present invention, the external reinforcing support structure is a two-dimensional stretched lattice structure.

[0011] A further improvement to the invention is that the external reinforcing support structure is X-shaped, which helps to enhance the gripping ability after the finger is inflated and bent.

[0012] A further improvement to the present invention is that the flexible sensor is designed with a zero Poisson's ratio, which helps to reduce lateral deformation interference.

[0013] In a further improvement to the present invention, the flexible sensor is embedded in the inside of the finger and is integrally connected to the finger body.

[0014] In a further improvement of the present invention, the material system of the flexible sensor in the flexible gripper is: polydimethylsiloxane (PDMS), carbon nanotubes (CNT), and cellulose nanoparticles (CNF).

[0015] A further improvement to the present invention is that the gas chamber array is filled with gas using an air pump.

[0016] The present invention also provides a mold for preparing a flexible finger in a self-sensing flexible pneumatic gripper, the mold comprising a finger body mold cavity, the finger body mold cavity comprising a gas chamber array thin-walled mold cavity on one side and a sensor thin-walled mold cavity on the other side.

[0017] In a further improvement to the present invention, the mold further includes an externally reinforcing support structure mold cavity located between adjacent thin-walled gas chamber mold cavities.

[0018] The present invention also provides a method for preparing the flexible finger of the self-sensing flexible pneumatic gripper using the mold, the method being prepared by a one-step molding process, comprising the following steps:

[0019] Liquid polydimethylsiloxane (PDMS) is injected into a mold, filling the gas chamber array thin-walled mold cavity, the sensor thin-walled mold cavity, and the external reinforcing support structure mold cavity. Metal electrode plates are placed on both sides of the reserved space of the sensor, so that the metal electrode plates directly contact the liquid polydimethylsiloxane (PDMS).

[0020] Place the mold in a vacuum drying environment;

[0021] Remove the cured mold from the drying oven;

[0022] The mixture that makes up the flexible sensor is poured into the sensor's reserved space located inside the thin-walled mold cavity of the sensor;

[0023] The mold was then placed in a vacuum drying environment.

[0024] The cured mold is removed from the drying oven, thus completing the curing preparation of the self-sensing flexible finger.

[0025] This method enables the simultaneous fabrication of flexible grippers and sensors.

[0026] In a further improvement of the present invention, the mixture constituting the flexible sensor is a mixture of polydimethylsiloxane (PDMS), carbon nanotubes (CNTs), and nanocellulose (CNF).

[0027] The polydimethylsiloxane (PDMS), carbon nanotubes (CNTs), and cellulose nanofibers (CNFs) were mixed and homogenized using a centrifuge and ultrasonic equipment until uniformly dispersed for later use.

[0028] The one-step molding self-sensing flexible pneumatic gripper proposed in this invention has the advantages of simple manufacturing process and integrated "drive-sensing" and can be applied to object grasping.

[0029] Compared with the prior art, the present invention has at least the following advantages and beneficial effects:

[0030] 1. This invention provides a one-step molding self-sensing flexible pneumatic gripper;

[0031] 2. The flexible sensor on the inner side of the flexible gripper proposed in this invention adopts a zero Poisson's ratio structure design, which helps to reduce lateral deformation interference;

[0032] 3. The flexible gripper proposed in this invention has a reinforced support structure on its outer side, which helps to enhance the gripping ability after the fingers are inflated and bent.

[0033] 4. The flexible self-sensing gripper proposed in this invention can achieve the simultaneous fabrication of flexible fingers and flexible sensors through a one-step molding process. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that similar reference numerals and letters in the following drawings indicate similar items. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0035] in:

[0036] Figure 1 This is a schematic diagram of a single finger model of the hand claw in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of a single finger mold model of the hand claw in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the zero Poisson's ratio sensor structure of the hand in an embodiment of the present invention;

[0039] Figure 4 This is a detailed schematic diagram of the external reinforcement support structure of the hand claw in an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of the simulated bending of the fingers in the claw of this invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of this specification. The singular forms "a," "described," and "the" as used in one or more embodiments of this specification and in the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used in one or more embodiments of this specification refers to and includes any or all possible combinations of one or more associated listed items.

[0043] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If a combination of technical solutions is contradictory or impossible to implement, such a combination should be considered nonexistent and not within the scope of protection claimed by this invention.

[0044] Example 1

[0045] Please see Figure 1 , Figures 3-5 The present invention provides a self-sensing flexible pneumatic gripper, comprising multiple flexible fingers, each of which includes a finger body. A gas chamber array 1-1 is arranged on one side of the finger body along the length direction of the finger body, and multiple flexible sensors 1-3 for force sensing are arranged on the other side of the finger body along the length direction of the finger body.

[0046] In this embodiment, the gas chamber array 1-1 includes multiple gas chambers, and the gas chambers are interconnected.

[0047] In this embodiment, an external reinforcing support structure 1-2 is provided between adjacent gas chambers.

[0048] In this embodiment, the external reinforcing support structure 1-2 is a two-dimensional stretched lattice structure, which helps to enhance the gripping ability after the finger is inflated and bent.

[0049] In this embodiment, the claw includes three flexible fingers. It is understood that in other embodiments, the number of flexible fingers in the claw can be other values.

[0050] In this embodiment, the flexible sensor 1-3 is embedded on the inside of the finger and is integrated with the finger body.

[0051] In this embodiment, the material system of the flexible sensor 1-3 is: polydimethylsiloxane (PDMS), carbon nanotubes (CNTs), and cellulose nanotubes (CNF). This material system is merely a specific example; other material systems may be used in other embodiments. The material system of the flexible sensor 1-3 is prior art and will not be elaborated upon here.

[0052] In this embodiment, as Figure 3 As shown, the flexible sensor 1-3 is designed with a zero Poisson's ratio, which helps to reduce lateral deformation interference.

[0053] In this embodiment, an air pump is also provided, which is used to inflate the gas chamber array 1-1 with air to drive the flexible fingers to bend, thereby enabling them to grasp objects.

[0054] This embodiment provides a self-sensing flexible pneumatic gripper. During operation, an air pump inflates the gas chamber array 1-1 (positive pressure). After the gas chambers are inflated, the flexible fingers can bend inward (e.g., ...). Figure 5 As shown in the figure, the gripper can hold the object, and the flexible sensor 1-3 located on the inside of the gripper can provide feedback on the gripping pressure, realizing force sensing when grasping the object.

[0055] Example 2

[0056] This embodiment provides a mold for preparing the self-sensing flexible pneumatic gripper described in Embodiment 1. The mold includes a finger body mold cavity, which includes a gas chamber array thin-walled mold cavity 2-1 located on one side and a sensor thin-walled mold cavity located on the other side.

[0057] In this embodiment, the mold also includes an external reinforcing support structure mold cavity 2-2 located between adjacent gas chamber thin-walled mold cavities 2-1.

[0058] Example 3

[0059] This embodiment uses the mold provided in Embodiment 2 to prepare the flexible finger in the self-sensing flexible pneumatic gripper provided in Embodiment 1 in one step.

[0060] Flexible fingers can be fabricated using a one-step molding process, including the following steps:

[0061] (1) Injecting liquid polydimethylsiloxane (PDMS) into a container such as... Figure 2 The mold shown is filled with a gas chamber array thin-walled mold cavity 2-1, a sensor thin-walled mold cavity, and an external reinforcing support structure mold cavity 2-2 (after the liquid PDMS is injected and solidified, it can form the thin wall of the gas chamber, the thin wall outside the sensor reserved space, and the external reinforcing support structure with a two-dimensional tensile lattice structure). Metal electrode sheets are placed on both sides of the sensor reserved space 2-3 so that they directly contact the liquid polydimethylsiloxane PDMS.

[0062] (2) Place the mold in a vacuum drying environment and bake at 50-80℃ for 1-5 hours;

[0063] (3) Mix polydimethylsiloxane (PDMS), carbon nanotubes (CNT) (0.8% wt), and nanocellulose (CNF) (0.8% wt), and homogenize them using a centrifuge and ultrasonic equipment. After uniform dispersion, the mixture is ready for use to obtain a uniformly mixed PDMS / CNT / CNF solution.

[0064] (4) Remove the cured mold from the drying oven;

[0065] (5) Pour the well-mixed PDMS / CNT / CNF solution into the sensor's reserved space 2-3;

[0066] (6) Place the mold in a vacuum drying environment again and bake it at 50-80°C for 1-5 hours;

[0067] (7) Take the cured mold out of the drying oven, disassemble the mold, and take out the sample. This completes the curing preparation of the self-sensing flexible finger.

[0068] The liquid polydimethylsiloxane (PDMS) injected in step (1) can simultaneously form the thin wall of the gas chamber and the external reinforcing support structure.

[0069] The foregoing embodiments of this invention detail a one-step molding self-sensing flexible pneumatic gripper, including its structural composition, fabrication process, and working principle. A one-step molding process enables the simultaneous fabrication of a flexible finger and a flexible sensor. The provided self-sensing flexible pneumatic gripper can bend by inflating the gas chamber array 1-1, thereby grasping objects, and achieves force sensing through the provided flexible sensors 1-3.

[0070] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0071] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A self-sensing flexible pneumatic gripper, characterized in that, The device includes multiple flexible fingers, each of which includes a finger body. A gas chamber array is arranged on one side of the finger body along the length of the finger body, and multiple flexible sensors for force sensing are arranged on the other side along the length of the finger body. The gas chamber array includes multiple gas chambers, which are interconnected. During operation, the flexible finger is driven to bend by inflating the gas chambers. The gas chamber array includes multiple gas chambers, with external reinforcing support structures provided between adjacent gas chambers; The self-sensing flexible pneumatic gripper is prepared by a one-step molding process; The external reinforcing support structure is a two-dimensional stretched lattice structure, and the external reinforcing support structure is X-shaped.

2. The self-sensing flexible pneumatic gripper according to claim 1, characterized in that, The flexible sensor is designed with a zero Poisson's ratio.

3. A self-sensing flexible pneumatic gripper according to any one of claims 1-2, characterized in that, The flexible sensor is embedded on the inside of the finger and is integrated with the finger body.

4. A mold for preparing the flexible finger in the self-sensing flexible pneumatic gripper according to any one of claims 1-3, characterized in that, The mold includes a finger body mold cavity, which includes a gas chamber array thin-walled mold cavity on one side and a sensor thin-walled mold cavity on the other side.

5. The mold according to claim 4, characterized in that, The mold also includes an externally reinforced support structure mold cavity located between adjacent thin-walled gas chamber mold cavities.

6. A method for preparing the flexible finger of the self-sensing flexible pneumatic gripper using the mold described in claim 5, characterized in that, The method achieves preparation through a one-step molding process, including the following steps: Liquid polydimethylsiloxane (PDMS) is injected into the mold, filling the thin-walled mold cavity of the gas chamber array, the thin-walled mold cavity of the sensor, and the mold cavity of the external reinforcing support structure. Metal electrode plates are placed on both sides of the reserved space of the sensor, so that the metal electrode plates directly contact the liquid polydimethylsiloxane (PDMS). Place the mold in a vacuum drying oven; Remove the cured mold from the drying oven; The mixture that makes up the flexible sensor is poured into the sensor's reserved space located inside the thin-walled mold cavity of the sensor; Place the mold back into the vacuum drying oven; Remove the cured mold from the drying oven to complete the curing preparation of the self-sensing flexible finger.

7. The method according to claim 6, characterized in that, The mixture that makes up the flexible sensor is a mixture of polydimethylsiloxane (PDMS), carbon nanotubes (CNTs), and cellulose nanofibers (CNFs).

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