Artificial muscle based on thermoplastic elastomer material

Abstract

The invention discloses an artificial muscle based on a thermoplastic elastomer material, the artificial muscle is composed of a muscle module which is attached to a base body and can realize bending, twisting or stretching and retracting actions of the base body, the muscle module is provided with a plurality of air bag units which are connected in series, the air bag units are cavity-divided air bags, and an innovative cavity-divided air bag structure is adopted, so that the air bag units are connected in series; and multi-degree-of-freedom motion adjustment is realized by independently controlling the air pressure of each air bag cavity. By means of the design, various actions such as bending, stretching and retracting and twisting can be completed, and the redundant size needing to be spliced by multiple modules in a traditional mechanical muscle is greatly simplified. According to the invention, the thermoplastic elastomer material is used as the air bag material, and the innovative cavity-divided air bag structure and the optimized air path design are adopted, so that the air bag structure has the remarkable advantages in the aspects of improving the efficiency, reducing the energy consumption, improving the response speed, improving the reliability, reducing the volume and the like.

Description

Technical Field

[0001] The invention relates to the field of pneumatic artificial muscles, in particular to an artificial muscle based on thermoplastic elastomer material. Background Art

[0002] With the continuous development of artificial intelligence and robotics, artificial muscles, as a technology that imitates the movement principles of biological muscles, have been widely used in various robots and intelligent devices. Traditional artificial muscle technology is mostly based on pneumatic or hydraulic drive principles, using rubber, silicone and other materials as the main materials of the airbag. Rubber airbags can simulate the contraction and extension of muscles when expanding or contracting, so they have been widely used in many fields such as bionic robots, rehabilitation equipment and soft robots.

[0003] The prior art of applying rubber airbags to artificial muscles includes the following:

[0004] 1) Publication No. CN106426146B discloses a double-acting pneumatic artificial muscle, which includes a push-stroke airbag, a pull-stroke airbag, end covers and fasteners. The end covers include end covers A and B; the pressure covers include pressure covers A, B, C, and D; the push-stroke airbag and the pull-stroke airbag are coaxially arranged inside and outside, and the pressure covers A and C are respectively connected to the two ends of the push-stroke airbag and fixedly connected to the end covers A and B; the pressure covers B and D are respectively connected to the two ends of the pull-stroke airbag and fixedly connected to the pressure covers A and C. When gas is rushed into the inner cavity of the push-range airbag, the gas pressure squeezes the inner wall to enlarge the diameter of the inner cavity, and the shuttle-shaped annular hole becomes narrower in the radial direction of the push-range airbag and wider in the axial direction, so that the push-range airbag is extended to achieve the push-range effect of the double-acting pneumatic artificial muscle; when gas is rushed into the inner cavity of the pull-range airbag, the pull-range airbag becomes larger in the radial direction and shortened in the axial direction, so that the pull-range airbag is shortened to achieve the pull-range effect of the double-acting pneumatic artificial muscle. The invention has the advantages of delicate structure, convenient use, simple operation, etc.

[0005] 2) Publication No. CN116038679B discloses a flexible robotic arm based on the coupling of memory alloy and pneumatic artificial muscle. In this technical application, the flexible robotic arm includes a fixed disk, a spacer disk, an airbag, a center rod, a base and an air supply pipe. The fixed disk is a circular thin disk installed at the end of the flexible robotic arm for fixing other components. The spacer disk is also a circular thin disk, which plays a supporting role in the middle of the flexible robotic arm. The airbag is a silicone thin shell structure, which provides power for the movement of the flexible robotic arm. The center rod material is nickel-titanium alloy, which has shape memory function, and the stiffness is enhanced after heating, which improves the stability of the flexible robotic arm. The base is a circular disk, which is used to fix other components and connect other control devices or power sources. The air supply pipe is rubber soft and provides power by supplying air to the airbag. The present invention realizes the movement and stiffness change of the flexible robotic arm through the cooperation of the airbag and the shape memory alloy center rod, reduces vibration and improves stability.

[0006] 3) Publication No. CN117001641A discloses a configurable grid structure pneumatic artificial muscle and functional device. In this technical application, it includes one or more array structures, each array structure includes a plurality of grid units connected together, each grid unit includes an active air cavity and a passive connection layer discontinuously connected to the active air cavity; the array structure has an initial state and a final state. When the array structure in the initial state is positively stimulated by positive pressure, the active air cavity in the array structure will expand and straighten, thereby driving the passive connection layer to adaptively deform, so the array structure will produce horizontal elongation movement and vertical contraction movement until the array structure reaches the final state. The present invention realizes a positive pressure contraction pneumatic artificial muscle with both high contraction rate and high output force by adopting a configurable grid-shaped pneumatic artificial muscle that contracts under positive pressure. It has good configurability and has the advantages of light weight, low cost, good flexibility and excellent comprehensive performance.

[0007] However, rubber airbags have some disadvantages in practical applications:

[0008] Large energy loss: Rubber material itself has large internal friction, which easily generates energy loss during expansion and contraction, resulting in low efficiency, especially when running for a long time, the energy consumption is large.

[0009] Slow response: Due to the high elasticity and hysteresis of rubber, airbags may have a large hysteresis response when air pressure changes, which limits their performance in applications that require fast and precise control.

[0010] Poor durability: Long-term use will cause the rubber material to age and wear, reducing its performance and life. Especially in the process of repeated expansion and contraction, the rubber airbag is prone to cracks, affecting the airtightness and performance of the airbag.

[0011] Large size: Traditional artificial muscle systems are usually composed of multiple modules, which makes the system bulky and is not conducive to the development of some precision applications and miniaturized equipment.

[0012] In addition, due to the material properties and the structure of the airbag itself, the existing artificial muscles still have problems such as large cavity volume, high gas consumption and slow response speed. Summary of the invention

[0013] The purpose of the present invention is to provide an artificial muscle based on thermoplastic elastomer material, which uses thermoplastic elastomer material as the airbag material, and adopts an innovative chamber airbag structure and an optimized air path design, which has significant advantages in improving efficiency, reducing energy consumption, increasing response speed, improving reliability and reducing volume.

[0014] To achieve the above purpose, the present invention provides the following technical solutions: an artificial muscle based on thermoplastic elastomer material, the artificial muscle is composed of a muscle module attached to a substrate and capable of bending, twisting or stretching the substrate, the muscle module has a plurality of airbag units connected in series, the airbag unit is a chambered airbag, and adopts an innovative chambered airbag structure, and realizes multi-degree-of-freedom motion regulation by independently controlling the air pressure of each airbag chamber. This design can complete multiple actions such as bending, stretching, twisting, etc., greatly simplifying the redundant volume of traditional mechanical muscles that require multiple modules to be spliced.

[0015] Preferably, the airbag is made of TPU material with elastic self-recovery and low hysteresis. TPU (thermoplastic elastomer material) has excellent elastic recovery ability (elongation at break>600%), can withstand large deformation and quickly return to its original state. This feature makes the artificial muscle show extremely high flexibility and adjustability when performing complex movements. In addition, the low hysteresis of the TPU material ensures that the artificial muscle can respond to changes in air pressure at the millisecond level, greatly improving the ability of precise control. Air pressure changes (0.1-0.5MPa) can trigger millimeter-level deformations within microseconds, thereby ensuring precise and rapid action response. Compared with traditional rubber airbags, the energy loss of TPU material is reduced by 30%, which makes it more efficient and energy-saving under long-term operation, and is particularly suitable for the application of high-precision rehabilitation robots and bionic manipulators.

[0016] Preferably, an isolation portion is provided between the upper, lower or left and right adjacent airbag units, and an air supply port for supplying air to the air path channel inside the airbag body is provided inside the isolation portion.

[0017] Preferably, the airbag unit comprises an airbag body and a film air cavity, the airbag body has an air path channel built in, the upper and lower ends of both sides of the airbag body are provided with first deformation parts, and the top and bottom ends of the airbag body are provided with second deformation parts.

[0018] Preferably, the thin film air cavity is arranged on the inner side of the airbag body, and the thin film air cavity includes an active air cavity and a passive air cavity. The passive air cavity is semicircular in shape, and is connected to the air path through a tracheal belt. The upper and lower ends of the outer circumference of the passive air cavity are respectively close to the first deformation parts at the upper and lower ends of both sides of the airbag body. The passive air cavity is supplied with air by the air path and contacts the first deformation part after expansion, so that the first deformation part is deformed.

[0019] Preferably, the cross-section of the active air cavity is in the shape of an arc, and the active air cavity is distributed at the upper and lower ends of the inner side of the airbag body. The active air cavity is connected to the passive air cavity through a tracheal band, and the upper and lower ends of the active air cavity respectively contact the second deformation part of the top and bottom ends of the airbag body, and the active air cavity is supplied with air by the passive air cavity to deform the second deformation part. The airbag body has multiple air passages built in, which can achieve deformation in different directions under different air pressures. The cross-section of the airbag body is octagonal, and multiple active and passive air cavities are provided. The coordinated effect of the active and passive air cavities enables the entire airbag to complete the task efficiently and stably, and realize multi-directional deformation through airflow control.

[0020] Preferably, the airbag body is made by a 3D printing process or an injection molding process, directly generating a closed air cavity and an embedded air path flow channel, thereby avoiding the risk of air leakage in a traditional bonding process.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The artificial muscle of the present invention is based on thermoplastic elastomer (TPU) material, adopts innovative chambered airbag structure and optimized air path design, which has significant advantages in improving efficiency, reducing energy consumption, improving response speed, improving reliability and reducing volume. It provides a more efficient, energy-saving, precise and durable artificial muscle solution for future robots, bionic equipment, rehabilitation systems and other fields.

[0023] The specific technical effects include:

[0024] 1. The TPU material used in the present invention has lower internal friction, reducing the energy loss during expansion and contraction. In addition, the low hysteresis of the TPU material enables the airbag to respond to air pressure changes within milliseconds, thereby achieving more precise and rapid control. Air pressure changes (0.1-0.5MPa) can trigger millimeter-level deformation at the microsecond level, improving the performance of artificial muscles in high-speed and high-precision control, and are suitable for occasions requiring precise operation.

[0025] 2. Through the design of the chambered airbag, multi-degree-of-freedom motion adjustment (such as bending, stretching, and twisting) can be achieved in a relatively small volume, reducing the redundant space caused by the splicing of multiple modules in the traditional artificial muscle system and improving the compactness of the structure. This makes the present invention suitable for space-constrained applications, such as small robots or bionic arms.

[0026] 3. The airbag of the present invention adopts 3D printing or injection molding technology to directly generate a closed air cavity and an embedded air path flow channel, which effectively avoids the leakage problem of the traditional bonding process and further improves the reliability and durability of the system.

[0027] 4. The present invention makes the use of gas more efficient through the optimized gas path structure and chamber design. Each airbag unit can be independently controlled as needed, avoiding excessive gas flow and waste. The air pressure control is more precise and efficient, further reducing the gas source consumption; in addition, the gas flow only occurs between the required chambers, avoiding unnecessary gas waste. The low hysteresis of the TPU material enables the airbag to respond quickly when the air pressure changes, achieving millimeter-level deformation.

[0028] 5. The artificial muscle of the present invention can achieve multi-directional deformation (bending, stretching, twisting) by adjusting different air pressures, which greatly enhances the adaptability and flexibility of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Detailed description of Embodiment 1 of the present invention;

[0030] Figure 2 It is a schematic diagram of the artificial muscle of the present invention being applied to a substrate and being able to achieve bending and twisting of the substrate;

[0031] Figure 3 is a schematic structural diagram of an airbag unit in Embodiment 2 of the present invention;

[0032] Figure 4 It is a schematic diagram of the structure of the airbag body and the film air cavity of Example 2 of the present invention.

[0033] In the figure: 1, isolation part; 2, air supply port; 3, airbag body; 301, air path; 302, first deformation part; 303, second deformation part; 4, film air cavity; 401, active air cavity; 402 and passive air cavity. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "vertical", "up", "down", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Example 1: Please refer to Figure 1-Figure 2 The present invention provides a technical solution: an artificial muscle based on thermoplastic elastomer material, the artificial muscle is composed of a muscle module attached to a substrate and capable of bending, twisting or stretching the substrate, the muscle module has a plurality of airbag units connected in series, the airbag unit is a chambered airbag, and adopts an innovative chambered airbag structure, and realizes multi-degree-of-freedom motion regulation by independently controlling the air pressure of each airbag chamber. This design can complete multiple actions such as bending, stretching, twisting, etc., greatly simplifying the redundant volume of traditional mechanical muscles that require multiple modules to be spliced.

[0038] In this embodiment, the airbag is made of TPU material with elastic self-recovery and low hysteresis. TPU (thermoplastic elastomer material) has excellent elastic recovery ability (elongation at break>600%), can withstand large deformation and quickly return to its original state. This feature makes the artificial muscle show extremely high flexibility and adjustability when performing complex movements. In addition, the low hysteresis of the TPU material ensures that the artificial muscle can respond to changes in air pressure at the millisecond level, greatly improving the ability of precise control. Air pressure changes (0.1-0.5MPa) can trigger millimeter-level deformations within microseconds, thereby ensuring accurate and fast action response. Compared with traditional rubber airbags, the energy loss of TPU material is reduced by 30%, which makes it more efficient and energy-saving under long-term operation, and is particularly suitable for the application of high-precision rehabilitation robots and bionic manipulators.

[0039] Figure 1 and Figure 2 In the present invention, the bending and twisting of the base can be achieved by controlling the air supply of the airbag units at different positions of the base.

[0040] In this embodiment, the airbag unit is made by 3D printing or injection molding, directly generating a closed air cavity and an embedded air path flow channel, avoiding the risk of air leakage in the traditional bonding process. In the specific implementation, laser sintering 3D printing technology can be used, and the specific implementation process includes:

[0041] Fill the TPU powder material into the powder bed of the SLS 3D printer. During the printing process, the temperature of the powder bed will be controlled within the sintering temperature range of the material to ensure that each layer of powder can gradually melt and fix into shape under the irradiation of the laser;

[0042] The CO2 laser scans the surface of the powder bed along a set path, melts the material according to the cross-sectional profile of each layer, and builds the complex geometric shape of the airbag and the embedded air path channel 301 layer by layer by precisely controlling the power, scanning speed and path of the laser;

[0043] After each laser sintering process, the platform drops a layer thickness (usually 0.1-0.2mm), and new material powder covers the sintered part, and the laser continues to scan the next layer until the entire airbag model is completed;

[0044] After printing, the airbag is cooled in the powder bed. The cooling time usually takes several hours to a day. This helps to avoid stress or deformation caused by temperature difference. After cooling, the airbag is removed from the powder bed.

[0045] The removed airbag needs to be post-processed to remove the unsintered powder attached to the surface or inside.

[0046] Laser sintering 3D printing technology can achieve 0.1mm flow channel accuracy, which makes the fine control of the air path more precise. The airbag's air pressure tolerance is increased by 50%, further improving the reliability and durability of the system.

[0047] Example 2: Please refer to Figure 1 , Figure 3 , Figure 4 The present invention provides a technical solution: an artificial muscle based on a thermoplastic elastomer material, the artificial muscle is a muscle module attached to a substrate and capable of bending, twisting or stretching the substrate, the muscle module has a plurality of airbag units connected in series, the airbag unit is a chambered airbag, and the upper, lower or left and right adjacent airbag units ( Figure 3 An isolation portion 1 is provided between the plurality of upper and lower adjacent airbag units, and an air supply port 2 for supplying air to the air path channel 301 inside the airbag body 3 is provided inside the isolation portion 1.

[0048] In this embodiment, the airbag unit has an airbag body 3 and a film air cavity 4. The airbag body 3 has an air path channel 301 built in. The upper and lower ends of both sides of the airbag body 3 are provided with first deformation parts 302, and the top and bottom ends of the airbag body 3 are provided with second deformation parts 303.

[0049] In this embodiment, the film air cavity 4 is arranged on the inner side of the airbag body 3, and the film air cavity 4 includes an active air cavity 401 and a passive air cavity 402. The passive air cavity 402 is semicircular in shape. The passive air cavity 402 is connected to the air path channel 301 through a tracheal belt. The upper and lower ends of the outer circumference of the passive air cavity 402 are respectively close to the first deformation parts 302 at the upper and lower ends of both sides of the airbag body 3. The passive air cavity 402 is supplied with air by the air path channel 301 and contacts the first deformation part 302 after expansion, so that the first deformation part 302 is deformed.

[0050] In this embodiment, the cross section of the active air cavity 401 is in the shape of an arc. The active air cavity 401 is distributed at the upper and lower ends of the inner side of the airbag body 3. The active air cavity 401 is connected to the passive air cavity 402 through the tracheal band. The upper and lower ends of the active air cavity 401 respectively contact the second deformation part 303 at the top and bottom ends of the airbag body 3. The active air cavity 401 is supplied with air by the passive air cavity 402 to deform the second deformation part 303. The airbag body 3 has multiple air passages 301 built in, which can achieve deformation in different directions under different air pressures. The cross section of the airbag body 3 is octagonal, and multiple active and passive air cavities 402 are provided. The coordinated effect of the active and passive air cavities 402 enables the entire airbag to complete the task efficiently and stably, and realize multi-directional deformation through airflow control.

[0051] This embodiment also provides the steps of applying the above-mentioned pneumatic muscle to the manipulator:

[0052] Integration of manipulator structure and airbag: Install the airbag unit (pneumatic muscle) on the driving part of the manipulator, such as the "fingers" or "wrist" of the manipulator. Each airbag unit can control the movement of one or more joints. The installation of the airbag needs to ensure that it does not interfere with other parts when inflated and can provide the necessary driving force. Connect the airbag to the joints or rods of the manipulator through suitable connectors (such as fixed brackets, connecting shafts, etc.). Ensure that the deformation of the airbag can be effectively transmitted to the moving parts of the manipulator.

[0053] Air pressure control and motion control: The expansion and contraction of the airbag is controlled by adjusting the air source pressure. The control system (such as PLC or microcontroller) controls the change of air pressure according to the input instructions, accurately adjusts the volume change of the airbag, and drives the manipulator to complete bending, extension, grasping and other movements. A closed-loop control system is used to feedback the deformation state of the airbag in real time, and the difference between the actual deformation and the target deformation of the airbag is fed back through sensors (such as pressure sensors, displacement sensors, etc.), and the air pressure is adjusted to accurately control the movement. Depending on the task, the control system can complete complex operations according to preset actions.

[0054] Movement and coordination: The robot can perform complex movements by using multiple airbag units to work together. For example, multiple airbag units connected in series can control the movement of different joints to achieve precise grasping, rotation, and handling. When multiple airbags act at the same time, their air pressure needs to be precisely controlled to synchronize in order to achieve coordinated movement of the robot. By independently controlling the air pressure of each airbag chamber, the coordinated movement of each joint or end effector can be flexibly achieved.

[0055] Action execution and feedback: By controlling the expansion and contraction of the airbag, the manipulator can complete tasks such as grasping, placing, and rotating. The inflation and exhaust volume of each airbag chamber controls the movement angle and speed of each joint. Sensors can be installed on the manipulator to monitor information such as joint angles and force changes during movement, and the air pressure of the airbag can be adjusted in real time through the feedback mechanism to ensure the accuracy and stability of the action.

[0056] The standard parts used in the present invention can all be purchased from the market, and the special-shaped parts can be customized according to the description and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the prior art. The machinery, parts and equipment all adopt conventional models in the prior art, and the circuit connection adopts the conventional connection method in the prior art, which will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0057] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An artificial muscle based on thermoplastic elastomer material, characterized in that: The artificial muscle is composed of a muscle module attached to a substrate and capable of realizing bending, twisting or stretching of the substrate. The muscle module has a plurality of airbag units connected in series, and the airbag units are divided-chamber airbags.

2. The artificial muscle based on thermoplastic elastomer material according to claim 1, characterized in that: The airbag unit is made of TPU material with elastic self-recovery and low hysteresis.

3. The artificial muscle based on thermoplastic elastomer material according to claim 1, characterized in that: The airbag unit comprises an airbag body (3) and a film air cavity (4), an isolation portion (1) is provided between the upper and lower or left and right adjacent airbag units, and an air supply port (2) is provided inside the isolation portion (1) for supplying air to the internal air path (301) of the airbag body (3).

4. The artificial muscle based on thermoplastic elastomer material according to claim 3, characterized in that: The airbag body (3) has an air passage (301) built in, the upper and lower ends of both sides of the airbag body (3) are provided with first deformation parts (302), and the top and bottom ends of the airbag body (3) are provided with second deformation parts (303).

5. The artificial muscle based on thermoplastic elastomer material according to claim 3, characterized in that: The film air cavity (4) is arranged on the inner side of the airbag body (3), and the film air cavity (4) comprises an active air cavity (401) and a passive air cavity (402). The passive air cavity (402) is semicircular in shape, and the passive air cavity (402) is connected to the airway channel (301) through a tracheal band.

6. The artificial muscle based on thermoplastic elastomer material according to claim 5, characterized in that: The upper and lower ends of the outer circumference of the passive air cavity (402) are respectively close to the first deformation parts (302) at the upper and lower ends of both sides of the airbag body (3). The passive air cavity (402) is supplied with air by the air passage (301) and contacts the first deformation part (302) after expansion, so that the first deformation part (302) is deformed.

7. The artificial muscle based on thermoplastic elastomer material according to claim 5, characterized in that: The cross section of the active air cavity (401) is in an arc shape. The active air cavity (401) is distributed at the upper and lower ends of the inner side of the airbag body (3). The active air cavity (401) is connected to the passive air cavity (402) through a tracheal band. The upper and lower ends of the active air cavity (401) respectively contact the second deformation part (303) at the top and bottom ends of the airbag body (3). The active air cavity (401) is supplied with air by the passive air cavity (402) to deform the second deformation part (303).

8. The artificial muscle based on thermoplastic elastomer material according to claim 3, characterized in that: The airbag body (3) is manufactured by a 3D printing process or an injection molding process.

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