A pneumatic bistable software driver with controllable preload and its use method

Abstract

The present invention discloses a pneumatic bistable soft driver with controllable preload and a method of use, comprising: a driving component, a fixing component for supporting the driving component and an air supply component for supplying air to the driving component; wherein the driving component comprises a first airbag component, a second airbag component attached to the first airbag component, a soft substrate arranged between the first airbag component and the second airbag component, and a hollow tube arranged at both ends of the first airbag component and the second airbag component; the air supply component comprises an air pipe connected to the first airbag component and the second airbag component and an external air pipe, and the external air pipe is connected to an air pump; the preload between the driving component and the fixing component is designed with different degrees of over-tight fit to achieve a controllable state. According to the present invention, the diversity of gas pre-bending is achieved, and energy is stored, and the driver transitions between two stable states, thereby achieving the purpose of high deformation and strong output force, and can be applied in multiple technical fields.

Description

Technical Field

[0001] The present invention relates to the technical field of soft actuators, and in particular to a pneumatic bistable soft actuator with controllable preload force and a use method thereof. Background Art

[0002] Traditional actuators are mainly rigid actuators, which have advantages in reverse driving force, design layout optimization and assembly and disassembly. However, it is difficult to make innovative breakthroughs in the overall design of rigid actuators, and due to the limitations of rigid structure and principle, it is difficult for its power density to reach the level of biological muscle, and it is difficult to deal with the problem of damaged component strength during external impact. In recent years, bionic technology has brought new development opportunities. Research on the motor ability of humans and animals has moved the actuator from a rigid structure to a flexible structure. Unlike rigid actuators that are mainly based on motors, reducers and torque sensors, flexible actuators are inspired by the rigid and flexible energy storage and release methods of animals. Soft materials are used as the main body of the actuator, which makes it produce a larger deformation than the object of action, thereby enhancing flexibility and achieving more complex movement. Existing flexible actuators are mostly based on shape memory alloy drives, dielectric elastomer drives, etc., which do not have advantages in response time and output power, and their environmental requirements greatly reduce their expected effects in related fields such as soft robots. Summary of the invention

[0003] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a pneumatic bistable soft actuator with controllable preload and a method of use, so as to achieve the diversity of gas pre-bending, and then store energy, and the actuator transitions between two stable states, so as to achieve the purpose of high deformation and strong output force, which can be applied in multiple technical fields. In order to achieve the above-mentioned purpose and other advantages of the present invention, a pneumatic bistable soft actuator with controllable preload is provided, comprising:

[0004] A driving assembly, a fixing assembly for supporting the driving assembly, and an air supply assembly for supplying air to the driving assembly;

[0005] The driving assembly includes a first airbag component, a second airbag component attached to the first airbag component, a soft substrate disposed between the first airbag component and the second airbag component, and a hollow tube disposed at both ends of the first airbag component and the second airbag component;

[0006] The air supply assembly includes an air pipe connected to the first airbag component and the second airbag component and an external air pipe, and the external air pipe is connected to an air pump;

[0007] The preload force between the driving component and the fixing component is controlled by different degrees of tight fit design, thereby fixing the driving device and providing structural conditions for pre-bending and energy storage of the soft substrate.

[0008] Preferably, the first airbag component and the second airbag component have the same structure, and the first airbag component is in a multi-cavity grid structure with ventilation holes, and the middle part of the edge of the first airbag component is connected to an air tube.

[0009] Preferably, the soft substrate is a plate-shaped structure, and a through hole is provided in the middle of the soft substrate, so that the soft substrate as a whole forms a "U" shape.

[0010] Preferably, the soft substrate is used to ensure the strength of the bistable flexible layer, and the material of the soft substrate is an elastic material with an elasticity higher than 2.5 GPa.

[0011] Preferably, the first airbag component includes an outer frame trunk and a plurality of branch parts arranged on two opposite inner sides of the outer frame trunk, and the branch parts are arranged relative to each other at intervals. The first airbag component expands the air cavities of the airbag layer through the branch parts to generate an extrusion force in the opposite direction.

[0012] Preferably, the material of the first airbag component and the second airbag component is a transparent TPU film, the material of the soft substrate is made of FR-4 epoxy resin, and a water-repellent film is attached to the soft substrate.

[0013] A method for using a pneumatic bistable soft actuator with controllable preload force comprises the following steps:

[0014] S1. The distance between the two hollow tubes of the driving component is adjusted by the fixing component and the soft base plate, and their positions are determined to achieve controllable preload force;

[0015] S2, applying a pre-bending force to the soft substrate of the driving assembly and the first airbag component and the second airbag component to be in a bent state so as to store energy;

[0016] S3, turning on the air pump of the air supply device, inflating the first airbag component through the vent pipe, and not inflating the second airbag component, the squeezing force of the soft substrate caused by the pressure difference on both sides continues to increase, and the squeezing force reaches a critical value;

[0017] S4, after the soft substrate jumps to the other side, the first airbag component is deflated and the second airbag component is inflated, forming a reverse pressure difference again to cause the soft substrate to jump downward, causing the entire driving module to arch downward;

[0018] S5. By alternately implementing S3 and S4, a periodic motion is generated to generate a stable propulsion force to enable the soft robot to move forward.

[0019] Compared with the prior art, the present invention has the following beneficial effects: through controllable preload, the degree of jump and the degree of energy storage and release can be effectively controlled; and the design of the opening in the middle of the soft substrate can effectively avoid the bistable stuck phenomenon caused by excessive preload. The organic coordination between the two enables the bistable driver to achieve maximum energy utilization. In addition, the circulating gas can be recycled, and the nearly zero-emission driving method helps to solve the problem of high energy consumption of the current driver, and the entire driving component and fixed component meet the definition of soft materials. When the external environment collides with the object of action, it can produce a larger deformation relative to the object of action, which helps to solve the problem of damaged component strength of existing rigid drivers during external impact.

[0020] Since gas is easy to obtain in nature, if it is in the form of a complete machine, it can also be driven with low energy consumption in a liquid environment such as water through the gravity inflow and gravity outflow of water. Therefore, a clean drive can be further realized.

[0021] The present invention can realize multi-stage parallel operation at the same time, thereby enhancing the driving power of the software driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0023] Figure 2 The first airbag component, the second airbag component and the soft substrate of the pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0024] Figure 3 A top view and a front view of the pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0025] Figure 4 A schematic diagram of a test fixture of a pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0026] Figure 5 A flow chart of a pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0027] Figure 6 A schematic diagram of the inflation bending of the pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0028] Figure 7 Two stable state switching of the pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0029] Figure 8 Two steady-state switching diagrams of the fixture test of the pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0030] Fig. 9 A schematic diagram of the prototype structure of the pneumatic bistable soft actuator with controllable preload force according to the present invention;

[0031] Fig.10 It is a schematic diagram showing the influence of adjusting the left and right ends of the soft substrate of the pneumatic bistable soft actuator with controllable preload force on the preload force according to the present invention. DETAILED DESCRIPTION

[0032] 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.

[0033] Reference Figure 1-10 , a pneumatic bistable soft actuator with controllable preload force, comprising:

[0034] A driving component, a fixing component for supporting the driving component and an air supply component for supplying air to the driving component. The preload force applied by the fixing component to the driving component affects its jump range and energy release size. The second airbag component is ventilated through the air supply component, and the first airbag component 1 is cut off from air. The size of the flexible driver of the present invention can be 60mm-360mm in length and 28mm-63mm in width.

[0035] Among them, Figure 1 As shown, the driving component includes a first airbag component 1, a second airbag component attached to the first airbag component 1, a soft substrate 2 arranged between the first airbag component 1 and the second airbag component, and a hollow tube 3 arranged at both ends of the first airbag component 1 and the second airbag component. The first airbag component 1 and the second airbag component are fixed at both ends by a pair of identical hollow tubes 3, forming their own structural restrictions and creating energy storage conditions; the hollow tube 3 is connected to the first airbag component 1, the second airbag component and the soft substrate. The tubular structure can be used to put the entire driving component into the slide groove of the fixed component to ensure that the entire device is not stuck when the driving component jumps. The hollow tube 3 can be fixed in a fixture or on other components to play a connecting role. The structure of the airbag component 1 and the soft substrate 2 is shown in FIG. Figure 2 shown.

[0036] The fixing assembly includes a test fixture and a prototype fixture. Figure 4 As shown, it includes a bottom plate 9, two support plates 7 arranged on the bottom plate, a fixing angle piece 8 for fixing the support plates, and a clamp body 6 arranged on the support plates. A scale 10 is arranged on the bottom plate. The clamp bodies 6 are fixed on the opposite surfaces of the two support plates, and a driver 5 is socially arranged between the two clamp bodies 6. The prototype fixture is shown in FIG. Fig. 9As shown, it includes a prototype upper shell 12, a lower shell 15 fixed to the upper shell, a driver 5 arranged at the connection between the upper shell and the lower shell, and a shell fixture 13 arranged at the driver, the shell fixture is fixed on the inner wall of the upper shell, a water spray port 17 is opened at one end of the lower shell away from the upper shell, the lower shell is filled with water 16, and a water-repellent film 14 is formed on the water surface, and the upper shell is filled with air 11. The test fixture and the prototype fixture are both provided with a slide groove, and the hollow tube 3 is provided with the slide groove, and the slide groove facilitates the movement of the hollow tube 3 with the deformation of the soft substrate, wherein the gas drive component can be designed by different fixing components, mainly by changing such as Fig.10 The distance between the inner ends of the two slides in the air supply module is l, so that the bistable state is in different curvatures to provide different preload forces. Figure 2 The air tube 4 in the device can be inflated and deflated by external air to control the expansion and contraction of the air cavity. The entire device is transformed between different stable states by the upper and lower air pressure differences to achieve jump changes.

[0037] like Fig.10 , the distance of the inner end of the card slot is controlled to be less than the length L of the substrate, so that a preload can be provided when the soft substrate is bent to maintain the bending, and l can be changed to change the size of the preload. At the same time, the preload cannot be too large, otherwise the critical threshold of the bistable jump will be too high, so that the substrate cannot complete the jump and is stuck. Therefore, the card slot should be reasonably adjusted according to the side pressure that can be provided, which is achieved in the present invention by changing the distance l of the inner end of the card slot.

[0038] like Figure 4 As shown in FIG. 1 , when there is no gas in the air cavity, the soft substrate 2 will be limited by the spacing of the hollow tubes and arch to one side, entering the initial pre-jump state. Figure 6 As shown, Figure 6 In a, when the air pressure in the upper air cavity is deflated, ΔP1=0, and the air pressure in the lower air cavity ΔP2>0, the bistable drive device bends downward; Figure 6 In b, the air pressure of the upper air cavity ΔP1>0, and the air pressure of the lower air cavity ΔP2=0, at which time the bistable drive device bends upward.

[0039] The air supply assembly includes an air pipe 4 connected to the first airbag component 1 and the second airbag component and an external air pipe, and the external air pipe is connected to an air pump;

[0040] The preload force between the driving component and the fixing component is controlled by different degrees of tight fit design, thereby fixing the driving device and providing structural conditions for pre-bending and energy storage of the soft substrate.

[0041] Furthermore, the first airbag component 1 has the same structure as the second airbag component, and the first airbag component 1 has a multi-cavity grid structure with ventilation holes, and the middle portion of the edge of the first airbag component 1 is connected to an air tube 4 .

[0042] Furthermore, the soft substrate 2 is a plate-like structure, and a through hole is opened in the middle of the soft substrate 2, so that the soft substrate 2 as a whole forms a "U" shape, so that the driving component overcomes the bottleneck of the bistable state, successfully breaks through the preload force, and realizes the jump between stable states.

[0043] Furthermore, the soft substrate 2 is used to ensure the strength of the bistable flexible layer, and the material of the soft substrate 2 is an elastic material higher than 2.5 GPa.

[0044] Furthermore, the first airbag component 1 includes an outer frame trunk and a plurality of branch parts arranged on two opposite inner sides of the outer frame trunk, and the relative branch parts are arranged at intervals. The first airbag component 1 expands the air cavities of the airbag layer through the branch parts to generate an extrusion force in the opposite direction. When no gas is ventilated, the overall structure is in a free state; the vent pipe 4 in the middle of the first airbag component 1 and the second airbag component is composed of an external air pipe, and an air hole is provided to connect to the air pump. ; The second airbag component is deflated while the first airbag component 1 is inflated, thereby constructing an air pressure difference on both sides of the soft substrate 2. When the extrusion force caused by the first airbag component 1 and the second airbag component reaches a critical value, the bistable substrate will enter an unstable state and jump to the stable state on the other side, so that the entire drive assembly arches upward, and the same is true for the lower side.

[0045] Furthermore, the materials of the first airbag component 1 and the second airbag component are transparent TPU films, the material of the soft substrate 2 is made of FR-4 epoxy resin, and a water-repellent film 14 is adhered to the soft substrate 2 .

[0046] Fig. 9 In the figure is a squid-like displacement motion prototype built using the bistable driver, which can be used to make the prototype move in the fluid.

[0047] Figure 7In the embodiment, the initial position of the bistable driver is at the stable position 1. When the upper air cavity is inflated, the extrusion force caused by the pressure difference on both sides of the substrate continues to increase. When the extrusion force reaches the critical value, the bistable substrate will enter an unstable state and jump to the stable position 2, causing the entire drive module to bend downward, and then bend under the preload. After the bistable substrate jumps to the other side, the lower air cavity is inflated and the upper air cavity is deflated, forming a reverse pressure difference again, causing the bistable substrate to jump from the stable position 2 to the stable position 1, causing the entire drive module to bend upward and maintain under the action of the preload. Repeating the above process continuously can realize the periodic jumping motion of the bistable substrate. This pneumatic bistable periodic motion can drive the movement of external components, which can be used to realize the squid-like drainage or bionic fish-like swinging forward of an object in a fluid.

[0048] The manufacturing process of the bistable drive device is as follows Figure 5 As shown in the flow chart, it mainly includes the production of airbag parts (artificial muscles) and elastic soft substrates (bones). The production of airbag parts mainly includes the preparation of materials, cutting and heat sealing of film materials, installation of airbag trachea and air tightness inspection of finished air cavity products.

[0049] In order to ensure that the air cavity does not undergo large elastic deformation during the inflation process, the material used for the airbag in this design is thermoplastic polyurethane (TPU) film, and the size and structure are as follows: Figure 2 As shown in Figure 1. As a new type of environmentally friendly material, TPU film material has the advantages of wear resistance, corrosion resistance, low cost, etc. It also has elasticity and plasticity similar to rubber. Under high temperature conditions, it can be melt-bonded and has certain self-repairing properties, which can meet the heat sealing operation in this design.

[0050] The soft substrate 2 is a skeleton support element of the first airbag component 1 and the second airbag component, and its external dimensions and structure are as follows: Figure 2 As shown in Figure 2, since the first airbag component 1 and the second airbag component need to produce a large deformation, a flexible material with a low elastic modulus is used. When the compressed gas is introduced into the first airbag component 1 and the second airbag component, it is difficult to control the shape characteristics after deformation, and it is necessary to "attach" to a substrate with a higher elastic modulus to maintain its own shape and control the degree of deformation. The first airbag component 1 and the second airbag component should be firmly and reliably bonded to the soft substrate 2 through double-sided adhesive, so that the first airbag component 1 and the second airbag component can pull the substrate to bend when deformed without falling off from the soft substrate 2.

[0051] A method for using a pneumatic bistable soft actuator with controllable preload force comprises the following steps:

[0052] S1, adjusting the distance between the two hollow tubes 3 of the driving component through the fixed component and the soft base plate 2, and determining their positions to achieve controllable preload force;

[0053] S2, applying a pre-bending force to the soft substrate 2 of the driving assembly and the first airbag component 1 and the second airbag component to bend them to store energy;

[0054] S3, turning on the air pump of the air supply device, inflating the first airbag component 1 through the vent pipe, and not inflating the second airbag component. The squeezing force of the soft substrate 2 caused by the pressure difference on both sides continues to increase, and the squeezing force reaches a critical value;

[0055] S4, after the soft substrate 2 jumps to the other side, the first airbag component 1 is deflated and the second airbag component is inflated, forming a reverse pressure difference again to make the soft substrate 2 jump downward, so that the entire driving module arches downward;

[0056] S5. By alternately implementing S3 and S4, a periodic motion is generated to generate a stable propulsion force to enable the soft robot to move forward.

[0057] The number of devices and processing scales described here are used to simplify the description of the present invention, and the application, modification and variation of the present invention will be obvious to those skilled in the art.

[0058] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A pneumatic bistable soft actuator with controllable preload, characterized in that: include: A driving assembly, a fixing assembly for supporting the driving assembly, and an air supply assembly for supplying air to the driving assembly; The driving assembly comprises a first airbag component (1), a second airbag component attached to the first airbag component (1), a soft substrate (2) arranged between the first airbag component (1) and the second airbag component, and a hollow tube (3) arranged at both ends of the first airbag component (1) and the second airbag component; The soft substrate (2) is a plate-like structure, and a through hole is provided in the middle of the soft substrate (2), so that the soft substrate (2) forms a "U" shape as a whole; The soft substrate (2) is used to ensure the strength of the bistable flexible layer, and the material of the soft substrate (2) is an elastic material with an elasticity higher than 2.5 GPa; The air supply assembly comprises an air pipe (4) connected to the first airbag component (1) and the second airbag component and an external air pipe, wherein the external air pipe is connected to an air pump; The preload force between the driving component and the fixing component is controlled by different degrees of tight fit design, thereby fixing the driving component and providing structural conditions for pre-bending and energy storage of the soft substrate.

2. A pneumatic bistable soft actuator with controllable preload as claimed in claim 1, characterized in that: The first airbag component (1) has the same structure as the second airbag component, and the first airbag component (1) has a multi-cavity grid structure with ventilation holes, and the middle part of the edge of the first airbag component (1) is connected to an air pipe (4).

3. A pneumatic bistable soft actuator with controllable preload force as claimed in claim 2, characterized in that: The first airbag component (1) comprises an outer frame trunk and a plurality of branch parts arranged on two opposite inner sides of the outer frame trunk, with the branch parts being arranged at intervals relative to each other. The first airbag component (1) expands the air cavities of the airbag layer through the branch parts, thereby generating a squeezing force in the opposite direction.

4. A pneumatic bistable soft actuator with controllable preload force as claimed in claim 1, characterized in that: The materials of the first airbag component (1) and the second airbag component are transparent TPU films, the material of the soft substrate (2) is made of FR-4 epoxy resin, and a water-repellent film is attached to the soft substrate (2).

5. A method for using a pneumatic bistable soft actuator with controllable preload force as claimed in any one of claims 1 to 4, characterized in that: S1, adjusting the distance between the two hollow tubes (3) of the driving component by fixing the component and the soft base plate (2), and determining their positions to achieve controllable preload force; S2, applying a pre-bending force to the soft substrate (2) of the driving component and the first airbag component (1) and the second airbag component, so that they are in a bent state and store energy; S3, turning on the air pump of the air supply device and inflating the first airbag component (1) through the vent pipe, while the second airbag component is not inflated, and the squeezing force on the soft substrate (2) caused by the pressure difference on both sides continues to increase until the squeezing force reaches a critical value; S4, after the soft substrate (2) jumps to the other side, the first airbag component (1) is deflated and the second airbag component is inflated, forming a reverse pressure difference again, causing the soft substrate (2) to jump downward, thereby causing the entire drive module to arch downward; S5. By alternately implementing S3 and S4, a periodic motion is generated to generate a stable propulsion force to enable the soft robot to move forward.

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