Integrated multi-degree-of-freedom soft actuator and mold

Abstract

The application discloses a kind of integrated multi-degree-of-freedom soft driver and mould, soft driver is integrally cast by flexible material, including the number of deformation cavity, for connecting the reinforcing rib structure of deformation cavity, and the middle cavity surrounded by deformation cavity and reinforcing rib structure;Deformation cavity includes several deformation layers and air holes;Deformation layer includes outer layer, inner layer bellows structure unit;Deformation layer is connected by reinforcing rib between it.The mould includes top cover mould, bottom cover mould, middle cavity mould, soft core and outer mould structure.When applying working medium, it can withstand greater pressure, produce greater deformation, and can quickly recover to initial state after large deformation;Soft demoulding technology is used, compared with the method of adding hard material to mould and then demoulding in traditional way, adding deformable soft material to mould for demoulding can greatly improve demoulding quality.

Description

Technical Field

[0001] This invention relates to an integrated multi-degree-of-freedom software driver and a mold for manufacturing the software driver. Background Technology

[0002] With the rapid development of artificial intelligence, robots have been widely applied in various fields, playing an irreplaceable role in areas such as industrial manufacturing, agricultural production, and national defense. Traditionally, robots are generally composed of rigid links connected by rotary joints, driven by rigid components such as hydraulic cylinders and motors. Each link achieves one degree of freedom. This type of rigid robot offers precise modeling capabilities and demonstrates significant advantages with the maturation of artificial intelligence and machine learning algorithms. However, it also faces a series of drawbacks, including high cost, complex structure, poor compliance, low safety, and difficulty in installation and maintenance. Furthermore, the rigid structure of robots reduces their environmental adaptability, severely limiting their performance in confined and unknown spaces.

[0003] To address the shortcomings of rigid robots, researchers have developed soft robots. Soft robots are primarily inspired by organisms in nature, such as the tentacles of an octopus or the trunk of an elephant. These robots can perform many complex movements in a simple and flexible manner, and through continuous evolution, have even developed a highly intelligent neuromechanical control system. Of course, the soft tissue acting as the actuator plays an irreplaceable role. On the one hand, soft tissue increases the contact area when adhering to the environment; on the other hand, it reduces the external forces generated during this process. This significantly reduces the environmental forces experienced by the organism, thereby improving its ability to interact with the environment and its own safety.

[0004] Software drivers, with their flexible and versatile structure, can cope with various complex environments and have a very wide range of application prospects. In recent years, researchers have conducted different types of research on the design and manufacture of software drivers.

[0005] The prior art CN109571820A discloses a method for processing rubber products based on wax mold core demolding. First, a paraffin core rod corresponding to the shape and size of the product to be processed is made, and a heat-insulating coating or curing material is applied to the outer surface of the paraffin at room temperature; second, the paraffin is removed by soaking in hot water to strengthen the hard outer shell and perform layered molding; finally, the internal paraffin is removed by high-temperature melting and kneading, etc., to obtain the rubber product. The silicone products made using the paraffin method in this patent are theoretically feasible, but difficult to implement, mainly due to the following reasons: (1) The hollow core of the actuator made of paraffin is relatively rough due to the physical properties of paraffin itself. As a result, the surface of the silicone product after the wax core melts is uneven and not smooth enough. Under the action of driving pressure, it is very easy to break, which leads to the failure of the experiment; (2) The surface of the silicone product made of paraffin is very easy to have paraffin residue. Even at a high temperature, it is difficult to completely melt it off. Moreover, the high temperature will directly cause the silicone product to age and reduce its service life; (3) The wax core made of paraffin is very easy to have uneven core, which means that the cast silicone product is of different thicknesses. When subjected to force, the thinner parts are very easy to break first, while the thicker parts do not break. Therefore, it is not feasible in actual use.

[0006] Existing technology CN112208099B discloses an apparatus for integral molding of complex internal structures of soft robots. The apparatus includes a cylindrical container, a mandrel, a deformable mold core shell, a pressure cap, and hexagonal socket head caps. First, the deformable mold core shell is fabricated, and the mold core is fitted onto it. Simultaneously, the mandrel is fixed at both ends with screws, and the deformation is adjusted. Second, after adjustment to a preset bending position, a coating agent is sprayed onto the inner wall of the cylindrical container, and silicone is injected into the container. Finally, after the silicone has completely cured, the end cap is removed, and the mold core shell is pulled forcefully to extract the mold core, thereby fabricating the soft robot. This patent uses a traditional manufacturing method, which involves placing a hard material in a mold, then pouring silicone, and finally removing the hard material inside. This method is feasible for some relatively simple soft robots, but it is impossible for soft robots with complex configurations. The main reasons are: (1) When using a hard material as the core for silicone pouring, the fit between the core component and the outer shell of the model is required to be high; (2) For soft robots with multiple cavities, multi-layered structures, and multiple functions, the internal cavities are generally more complex. A single actuator cavity may contain multiple folded structures, making it impossible to demold the hard core using this method; (3) The prior art states that after the silicone is poured, the core shaft and outer shell can be extracted by forcefully pulling the deformable core shell. This is misleading. After silicone is fully cured, the surface tension is high, and there is almost no gap when it comes into contact with the mold, which makes it easy to adhere to the hard mold. Forcefully pulling not only has no effect but will also have the opposite effect, easily causing damage to the silicone product. Therefore, this solution is not feasible for actuators with complex structures.

[0007] Existing technology CN112622132A discloses a silicone cavity lost foam casting mold and method. The mold includes an outer mold, a core, and a hollow cavity formed by the outer mold and the core. The shape of the hollow cavity is adapted to the cavity to be cast. One end of the hollow cavity is open, and the other end is closed. The open end is used to pour in fluid silicone, and the closed end is used to connect the outer mold and the core. The core and the hollow cavity are made of a fragile material. The silicone cavity lost foam casting mold and method proposed in this document adopt an integrated molding method. By changing the shape of the outer mold and core structure as needed, a cavity of a specific structural shape can be cast. After casting, the cavity can be crushed to achieve demolding. This method has the same problems as the existing technologies mentioned above, mainly as follows: (1) If 3D printed plaster is used as the cavity, the material itself is relatively rough, and the cast silicone product is also relatively rough, which is not suitable for use in some tight structural parts; (2) When plaster is placed in the mold as the lost foam core, and then the plaster is crushed and removed by external force, if the crushed plaster cannot be completely removed, the residual plaster powder in the silicone product will cause fatal damage to the silicone product; (3) Finally, plaster is hygroscopic, and when silicone liquid is poured in, the surface of the plaster will become damp, which is detrimental to the silicone liquid and may lead to the silicone liquid not curing or curing delay. In summary, the casting method of using plaster cavity is not feasible in fine or large-scale production.

[0008] The prior art CN112405589B discloses a flexible actuator based on a bellows. The actuator consists of an upper base plate, a lower base plate, several air pipes, an inner bellows, an outer bellows, and several folding partitions. The folding partitions are used to connect the inner and outer bellows and divide the outer and inner bellows into several chambers. An air pipe or drive line is installed in each chamber to drive its movement. After in-depth analysis, the following problems were found in this bellows actuator: (1) The bellows and folded partitions are 3D printed. Due to the complex structure of the bellows, it is impossible to print thin-walled structures or inclined wall structures with a small angle to the direction of gravity. The success rate of the printed products is low, the printing accuracy is low and the scalability is poor. In addition, the rough surface can increase the fluid resistance and reduce the pressure resistance of the actuator; (2) When the folded partitions are connected to the bellows structure, the bellows are completely connected. When pressure is applied to one of the cavities, the cavity will bend and deform. At the same time, the other cavities will also be deformed in the same way because they are completely connected. Specifically, the deformation is poor and the independent control of each cavity cannot be fully realized; (3) Since the folded partitions are not designed uniformly, when the folded partitions are connected to the bellows and the bellows are controlled to bend, the bellows are very easy to twist and cannot achieve the desired bending effect. In summary, it is almost impossible to achieve the actual bending effect when using this bellows for bending control due to the limitations of the structure itself.

[0009] The prior art CN111452066A discloses a fully flexible bionic pneumatic manipulator. The manipulator unit includes a bionic execution system and a drive system. The bionic execution system includes a cylindrical shell with a corrugated structure made of flexible material and at least three air cavities made of flexible material. The cylindrical shell has an overall elephant trunk structure. The air cavities are hollow, variable-diameter rotating bodies. The multiple air cavities are evenly arranged inside the shell, with one end closed and the other end open. The opening is bonded with an adhesive. The following problems can be found after analysis: (1) The article says that the structure is biomimetic elephant trunk structure. It should be noted that the muscle tissue of the elephant trunk belongs to the muscle-type hydrostatic skeletal structure, which is composed of intersecting transverse and longitudinal muscles. The transverse muscles have a certain rigidity when they contract. However, the corrugated tube structure designed in the article is very easy to twist and deform under pressure, and cannot achieve the desired experimental effect at all; (2) The inner and outer corrugated tubes in the article are bonded by silicone adhesive, which has poor feasibility. Specifically, if the bonding is not firm, the internal actuator is very easy to fall off and the corrugated tube will fail, and the so-called grasping behavior cannot be achieved; (3) Simply using the inner and outer corrugated tube actuators, and the outer corrugated tube is a flat structure, cannot achieve the grasping behavior of different objects. The main manifestation is that when positive pressure is applied to the inner corrugated tube, the corrugated tube is stretched and there is no grasping behavior. Or when negative pressure is applied, the corrugated tube is shortened. At this time, there may be some grasping behavior, but the grasping force is very small and cannot achieve the so-called "twisting the bottle cap" behavior at all. In conclusion, the bellows actuator manufactured using this method is not practically feasible.

[0010] The prior art CN114516070A discloses a variable stiffness soft robotic arm, including two connecting seats and multiple corrugated pipe modules disposed between the two connecting seats. The multiple corrugated pipe modules are arranged in parallel. The corrugated pipe includes an inner corrugated pipe, an outer corrugated pipe, and a variable stiffness body. The inner corrugated pipe forms a main ventilation chamber, and a variable stiffness cavity is formed between the inner and outer layers. The variable stiffness cavity consists of two or more hard particle layers. The hard particle layer includes a flexible connecting layer and hard particles uniformly arranged in the flexible connecting layer. Adjacent hard particles are connected together, and the hard particle layer located on the inner side is connected to the outer wall of the inner corrugated pipe. Comparative analysis with this bellows actuator revealed two main issues: First, its manufacturing process is quite complex, requiring the filling of rigid particles between the inner and outer bellows layers. If the bellows leak or break during manufacturing, the actuator will fail entirely. Second, the rigid particles reduce the effective elongation of the bellows. Specifically, when negative pressure is applied to the bellows actuator, the bellows contracts while the distance between the rigid particles decreases, significantly reducing expansion and contraction. Therefore, this design is generally undesirable in practical applications. Summary of the Invention

[0011] The purpose of this invention is to provide an integrated multi-degree-of-freedom software driver and a mold for manufacturing the integrated multi-degree-of-freedom software driver.

[0012] To solve the above-mentioned technical problems, the objective of this invention is achieved as follows:

[0013] The present invention relates to an integrated multi-degree-of-freedom software actuator, which is integrally cast from a flexible material and includes a set number of deformation cavities, a reinforcing rib structure for connecting the deformation cavities, and an intermediate cavity surrounded by the deformation cavities and the reinforcing rib structure.

[0014] The deformation cavity includes several deformation layers and air holes disposed on the end face for airflow; the deformation layer includes an outer corrugated pipe structural unit and an inner corrugated pipe structural unit, and a cavity structure between the two structural units; the deformation layers of two horizontally adjacent deformation cavities are connected by reinforcing ribs.

[0015] Based on the above scheme and as a preferred embodiment of the above scheme: the flexible material is silicone, hydrogel, gelatin or PDMS.

[0016] Based on the above scheme and as a preferred embodiment of the above scheme: the outer corrugated pipe structural unit includes an outer corrugated pipe trough and an outer corrugated pipe peak; the inner corrugated pipe structural unit includes an inner corrugated pipe trough and an inner corrugated pipe peak; the end of the reinforcing rib connects the outer corrugated pipe structural unit and the inner corrugated pipe unit at the trough.

[0017] Based on the above scheme and as a preferred embodiment of the above scheme: the peaks and / or troughs of the outer corrugated pipe structural unit and the inner corrugated pipe structural unit are U-shaped, S-shaped, Ω-shaped or ∧-shaped.

[0018] The present invention also relates to a mold for manufacturing an integrated multi-degree-of-freedom soft actuator, including a top cover mold and a bottom cover mold, and an intermediate cavity mold, a soft core and an outer mold structure fixed between the top cover mold and the bottom cover mold;

[0019] The soft core is disposed on the outside of the central cavity mold, and the outer mold structure is disposed on the outside of the soft core to form the casting cavity of the soft actuator; the surface of the soft core is coated with a release agent.

[0020] Based on the above scheme and as a preferred embodiment of the above scheme: the intermediate cavity mold is provided with an intermediate cavity mold pouring hole and an intermediate cavity mold positioning hole arranged along its axial direction; the bottom of the intermediate cavity mold is provided with a bottom overflow channel that communicates with the intermediate cavity mold pouring hole and the casting cavity.

[0021] The soft core is corrugated to match the cavity structure inside the deformation cavity, and is provided with a soft core fixing through hole, and a soft core bottom positioning boss is provided at its bottom.

[0022] The outer mold structure is composed of several outer mold structure units that are sealed and connected. Each outer mold structure unit is provided with a first positioning hole, a second positioning hole, and a protrusion. The first positioning hole penetrates through the outer mold structure unit, and the second positioning hole is used for positioning and connecting two adjacent outer mold structure units. The protrusion protrudes inward and passes through the gap between adjacent soft cores to contact the intermediate cavity mold.

[0023] Based on the above scheme and as a preferred embodiment of the above scheme: the top cover mold is provided with a top cover pouring hole, a top cover soft core positioning hole, a top cover middle cavity mold positioning hole and a pouring overflow hole; the top cover pouring hole is located and connected to the middle cavity mold pouring hole.

[0024] Based on the above scheme and as a preferred embodiment of the above scheme: the top cover mold is further provided with an overflow limiting protrusion to block the overflow of the pouring liquid.

[0025] Based on the above scheme and as a preferred embodiment of the above scheme: the bottom cover mold is provided with a bottom cover outer mold positioning hole, a bottom cover middle cavity mold positioning hole, a bottom cover soft core positioning groove and a bottom cover soft core positioning hole; the bottom cover soft core positioning hole is located in the bottom cover soft core positioning groove; the bottom cover soft core positioning groove cooperates with the soft core bottom positioning boss.

[0026] Based on the above scheme and as a preferred embodiment of the above scheme: the release agent is a water-based release agent, a polyurethane water-based release agent, or a lipid-based release agent.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The software driver of the present invention is made of a super-elastic flexible material. When the working medium is applied, the software driver can withstand a large pressure and generate a large deformation, and can quickly return to the initial state after the large deformation.

[0029] (2) The software driver of the present invention has multiple elastic cavities, and each elastic cavity has a multi-layer structure, which can realize directional deformation of multiple degrees of freedom and generate elastic bending;

[0030] (3) The soft driver of the present invention can integrate multiple control devices, which improves the integration of the soft robot and can be applied to more severe environments;

[0031] (4) The software driver of the present invention adopts an integrated casting molding method, which disassembles the mold into multiple parts, simplifies the casting steps, shortens the casting time, improves the casting success rate, and can obtain a high-quality software driver.

[0032] (5) The soft driver of the present invention adopts soft demolding technology. Compared with the traditional method of adding hard materials into the mold and then demolding, adding deformable soft materials into the mold for demolding can greatly improve the demolding quality.

[0033] (6) This invention can be widely applied to the design and manufacture of soft robots with various complex configurations. It is easy to operate and can be designed and demolded at room temperature. Attached Figure Description

[0034] Figure 1 This is a three-dimensional structural diagram of an integrated multi-degree-of-freedom software driver;

[0035] Figure 2 yes Figure 1 A sectional view;

[0036] Figure 3 This is a structural diagram of an integrated multi-degree-of-freedom software actuator bent at 30°.

[0037] Figure 4 This is a cross-sectional schematic diagram of an integrated multi-degree-of-freedom software driver;

[0038] Figure 5 This is a longitudinal cross-sectional view of an integrated multi-degree-of-freedom software driver;

[0039] Figure 6 It involves grabbing assemblies;

[0040] Figure 7 It is a crawler assembly;

[0041] Figure 8 This is a cross-sectional parameter diagram of the corrugated section of an integrated multi-degree-of-freedom software actuator;

[0042] Figure 9 This is a bending simulation diagram of an integrated multi-degree-of-freedom software actuator;

[0043] Figure 10 It is a diagram of the mold assembly;

[0044] Figure 11 It is mold assembly Figure 1 ;

[0045] Figure 12 It is mold assembly Figure 2 ;

[0046] Figure 13 It is mold assembly Figure 3 ;

[0047] Figure 14 It is mold assembly Figure 4 ;

[0048] Figure 15It is a 3D structural diagram of the top cover mold;

[0049] Figure 16 It is a three-dimensional structural diagram of the cavity mold;

[0050] Figure 17 It is a 3D structural diagram of the soft core;

[0051] Figure 18 This is a three-dimensional structural diagram of the outer mold structure;

[0052] Figure 19 It is a three-dimensional structural diagram of the bottom cover mold;

[0053] Figure 20 This is a diagram of a soft core mold assembly;

[0054] Figure 21 This is a 3D structural diagram of the soft core mold cover;

[0055] Figure 22 This is a 3D structural diagram of the lower cover of the soft core mold.

[0056] The markings in the diagram are explained as follows: 1: Pore; 2: Deformation cavity; 3-1, 3-2, 3-3: Reinforcing rib structure; 4-1: Outer corrugated tube trough; 4-2: Outer corrugated tube peak; 5-1: Inner corrugated tube trough; 5-2: Inner corrugated tube peak; 6: Intermediate cavity; 7: Deformation layer; 8: Reinforcing rib gap; 9: Reinforcing rib; 10-1: Upper edge of reinforcing rib; 10-2: Lower edge of reinforcing rib; 11: Reinforcing rib gap; 12: Top Cover mold; 12-1: Pour overflow hole; 12-2: Top cover soft core positioning hole; 12-3: Top cover middle cavity mold positioning hole; 12-4: Top cover pouring hole; 12-5: Overflow limiting protrusion; 13: Middle cavity mold; 13-1: Middle cavity mold structural component one; 13-2: Middle cavity mold structural component two; 13-3: Middle cavity mold structural component three; 13-4: Middle cavity mold structural component four; 13-5: Middle cavity 13-6: Mold positioning hole; 13-7: Bottom overflow channel; 14: Soft core; 14-1: Soft core fixing hole; 14-2: Corrugated structure; 14-3: Soft core bottom positioning boss; 15: Outer mold structure; 15-1: Outer mold first positioning hole; 15-2: Outer mold second positioning hole; 15-3: Outer mold structure protrusion; 16: Bottom cover mold; 16-1: Bottom cover outer mold positioning hole; 16-2: Bottom cover middle... 16-3: Positioning hole for the cavity mold; 16-4: Positioning groove for the soft core of the bottom cover; 17: Upper mold for the soft core; 17-1: Positioning hole for the upper mold for the soft core; 17-2: Overflow hole for the pouring of the upper mold for the soft core; 17-3: Through hole for the positioning post of the upper mold for the soft core; 17-4: Pouring hole for the upper mold for the soft core; 18: Positioning post; 19: Lower mold for the soft core; 19-1: Positioning hole for the lower mold for the soft core; 19-2: Through hole for the positioning post of the lower mold for the soft core. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0058] Combination Figures 1 to 10 This invention describes the software actuator involved in the present invention. The integrated multi-degree-of-freedom software actuator involved in this embodiment is integrally cast from a flexible material and includes a predetermined number of deformation cavities 2, reinforcing rib structures 3-1, 3-2, and 3-3 for connecting the deformation cavities, and an intermediate cavity 6 enclosed by the deformation cavities 2 and the reinforcing rib structures. Each deformation cavity 2 includes several deformation layers 7 and air holes 1 disposed on the end face for airflow passage. Each deformation layer 7 includes an outer corrugated pipe structure unit and an inner corrugated pipe structure unit, and a cavity structure between the two structure units. Two horizontally adjacent deformation layers of the deformation cavities are connected by reinforcing ribs 9. The reinforcing rib structures 3-1, 3-2, and 3-3 are composed of multiple reinforcing ribs 9.

[0059] An integrated multi-degree-of-freedom software actuator can have multiple deformation cavities, such as 3, 4, or 5, or even more. In this embodiment, 3 deformation cavities 2 are used as an example for illustration. Each deformation cavity 2 has an air hole 1 on its end face for independently supplying air to each deformation cavity.

[0060] Furthermore, the deformation cavity 2 can be fan-shaped or other shapes; in this embodiment, a fan shape is chosen. Rounded corners are incorporated into all parts of this integrated multi-degree-of-freedom soft actuator, making the transitions between parts smooth and resulting in a soft robot body and various connecting components with a gentle feel.

[0061] Furthermore, during the casting of the integrated multi-degree-of-freedom soft actuator involved in this embodiment, a superelastic flexible material with low viscosity, high hardness, high tear strength, good flowability, and long operating time is preferentially used. Specifically, the flexible material is silicone, hydrogel, gelatin, or PDMS, etc. In this embodiment, silicone is used.

[0062] In this embodiment, the outer corrugated pipe structural unit includes an outer corrugated pipe trough 4-1 and an outer corrugated pipe peak 4-2; the inner corrugated pipe structural unit includes an inner corrugated pipe trough 5-1 and an inner corrugated pipe peak 5-2; the end of the reinforcing rib 9 connects the outer corrugated pipe structural unit and the inner corrugated pipe unit at the trough, that is, there is a reinforcing rib gap 11 between two adjacent reinforcing ribs 9.

[0063] Furthermore, the crests and / or troughs of the outer and inner bellows structural units are U-shaped, S-shaped, Ω-shaped, or ∧-shaped. In this embodiment, the crests and troughs are U-shaped. A reinforcing rib 9 is designed between each adjacent U-shaped deformation layer 7, i.e., a reinforcing rib structure is provided at the joint between two adjacent deformation cavities 1. The number of deformation layers in each integrated multi-degree-of-freedom software actuator can be set independently; in this embodiment, nine deformation layers 7 are selected. A reinforcing rib 9 is provided between two horizontally adjacent deformation layers 7. This reinforcing rib 9 is integrally cast with the deformation cavity 2, enabling the connection of two adjacent deformation cavities 2.

[0064] The reinforcing rib structure in this embodiment has the following advantages:

[0065] A. From an intuitive point of view, the reinforcing rib structure can be used to divide adjacent deformation cavities 2, making each deformation cavity 2 an independent cavity. In this example, the reinforcing rib structure divides the soft actuator into three fan-shaped deformation cavities 2 with complete structures, which can deform independently under pressure, ensuring the maximum value of the deformation space of each deformation cavity 2.

[0066] B. In previous designs, when positive pressure was applied to any of the deformation cavities 2, the cavity would first undergo structural expansion deformation. When the structural deformation reached its maximum value, the adjacent unpressurized deformation cavities would deform due to the force, which was undesirable. Secondly, when the structure could no longer deform, material deformation would occur, causing all adjacent deformation cavities to undergo significant deformation, rendering the obtained deformation parameters meaningless. However, the addition of this reinforcing rib structure changes this. Simply put, this reinforcing rib structure acts as a constraint structure, effectively constraining the deformation of each deformation cavity and each layer of deformation cavities. Further, when one of the deformation cavities 2 is subjected to force and deformation, the reinforcing rib structure acts as a thickening treatment at the connection point. When the force is transmitted to the connection point, the reinforcing rib can bear the force first, thus diluting most of the force. Simultaneously, adjacent reinforcing ribs can also dilute some of the force, resulting in almost no force transmitted to the adjacent deformation cavities 2, thus not affecting the deformation of the adjacent cavities.

[0067] C. The reinforcing rib structure can protect each deformation cavity. This is mainly because when the deformation cavity is subjected to peak force, the arc-shaped connection of the deformation cavity is prone to cracking. The addition of the reinforcing rib structure is equivalent to applying a reverse force at that point, thereby ensuring that the point will not be damaged due to excessive pressure.

[0068] D. The reinforcing ribs of each deformation layer 7 are only connected to adjacent deformation layers 7, so that they will not interfere with other deformation layers. Furthermore, there is a certain gap between each reinforcing rib 9. The purpose of this is to provide a certain heat dissipation function when the controller of the driver is integrated into the central cavity 6, and to add materials or devices there to improve the overall rigidity of the driver.

[0069] The integrated multi-degree-of-freedom software driver involved in this embodiment, such as Figure 2 As shown, to ensure a large deformation effect in the cavity, the inner layer of the actuator is also designed as a bellows structure. The cavity structure inside the deformation cavity 2 can integrate the actuator's control components, thereby improving the system's integration level.

[0070] The diagram illustrates the bending effect when negative pressure is applied to one of the deformation cavities and positive pressure is applied to the other two. Deformation layer 7 shows the bending behavior of the actuator when positive pressure is applied to one of the deformation cavities. Figure 3 A schematic diagram of a 30° bending deformation. The reinforcing rib gap 8 is a void structure between the middle reinforcing ribs, where special structures can be installed to improve the overall rigidity of the driver, as well as for heat dissipation in the integrated system, etc.

[0071] like Figure 4 As shown in the cross-sectional view, the reinforcing rib 9 can be seen. The reinforcing rib 9 is located at the transition of each deformation layer and can connect two adjacent deformation cavities together. Figure 5 As shown, the upper boundary 10-1 and the lower boundary 10-2 of the reinforcing rib connect the upper and lower deformation layers, respectively.

[0072] Figure 6 and Figure 7 It is a diagram of a soft robotic arm system formed by assembling four soft actuators together, the difference being... Figure 6 The process involves applying negative pressure to any one of the deformation cavities in the actuator and positive pressure to the other two cavities. Then, the actuators with the same bending direction are assembled end to end, thus creating a larger robotic arm that can bend like an elephant's trunk and be used for object grasping experiments. Figure 7 By connecting the end faces of soft actuators with inconsistent bending directions, a worm-like or snake-like crawling soft robot can be formed. Similarly, other structures can be assembled from the actuators to create more robot configurations for a variety of complex tasks.

[0073] In this embodiment, the bellows section adopts a U-shaped bellows design, and its overall structure resembles the capital letter "U". The main reason for this design is that it can absorb more lateral deformation, i.e., displacement deformation, and can withstand greater pressure when subjected to stress. During the design process, the thickness, number of layers, and corrugation spacing of the bellows will significantly affect its stress resistance and performance. Figure 8 The following diagram of bellows parameters will be used as an example for explanation.

[0074] for Figure 8 Let the number of bellows be n. Then the total length of the bellows can be expressed as:

[0075] L=

[0076] in, The radius of the wave crest, The radius of the trough. mm, mm, wave distance mm, bellows thickness mm, distance between wave crests mm, the distance between troughs mm. For the calculation of the single-wave stiffness formula of multi-layered corrugated pipes, the EJMA standard can be used:

[0077]

[0078] in, The average diameter of the bellows is approximately 80 mm. The elastic modulus of the bellows material at room temperature is approximately 2.14 MPa. This refers to the actual thickness of a single layer of material in the corrugated pipe. mm, and Where t is the nominal thickness The inner diameter of the corrugated pipe is approximately 64 mm, and n represents the number of material layers in the corrugated pipe, which is 2. The difference between the wave height and the corrugated pipe material thickness nt. To ensure that the properties of the U-shaped corrugated pipe differ from those of a lath beam by a correction factor, the following calculation method can be used:

[0079]

[0080] Where q is the wave distance. mm, calculate The axial stiffness of the bellows can then be calculated:

[0081]

[0082] in Let N be the axial stiffness of a single wave of the bellows, and N be the wave number of the bellows. The detailed parameters of the bellows can be designed and manufactured using the above formula.

[0083] When this "U-shaped" bellows is used in the design of the actuator's main structure, when pressure is applied to one of the deformation cavities, it can achieve a large bending deformation angle in a short time, generating a large deformation displacement, such as... Figure 9 The simulation data shows that when a positive pressure of 6 kPa is applied to one of the cavities, its bending deformation displacement reaches 44.16 mm, and its bending deformation angle is about 50° in about 0.2 s.

[0084] This embodiment also relates to a mold for manufacturing an integrated multi-degree-of-freedom soft actuator, including a top cover mold 12 and a bottom cover mold 16, and an intermediate cavity mold 13, a soft core 14, and an outer mold structure 15 fixed between the top cover mold 12 and the bottom cover mold 16. The soft core 14 is disposed on the outside of the intermediate cavity mold 13, and the outer mold structure 15 is disposed on the outside of the soft core 14 to form the casting cavity of the soft actuator; the surface of the soft core 14 is coated with a release agent.

[0085] In this embodiment, when assembling the mold, the bottom cover mold 16 is first placed on a horizontal surface, the middle cavity mold 13 is placed in the center of the bottom cover mold 16 and fixed by the positioning pin 18; then the outer mold structure 15 is placed on the bottom cover mold 16 and fixed by the positioning pin 18; finally, the soft core 14 cast by the soft core mold is placed in the assembled mold and fixed by the positioning pin 18, and then the top cover mold 12 is covered, thus completing the assembly of a complete set of molds.

[0086] The top cover mold 12 is provided with a top cover pouring hole 12-4, a top cover soft core positioning hole 12-2, a top cover middle cavity mold positioning hole 12-3, and a pouring overflow hole 12-1; the top cover pouring hole 12-1 is located and connected to the middle cavity mold pouring hole 13-6.

[0087] The intermediate cavity mold 13 is provided with an intermediate cavity mold pouring hole 13-6 and an intermediate cavity mold positioning hole 13-5 arranged along its axial direction; the bottom of the intermediate cavity mold 13 is provided with a bottom overflow channel 13-7 that communicates with the intermediate cavity mold pouring hole 13-6 and the casting cavity.

[0088] The soft core 14 has a corrugated structure 14-2 that matches the cavity structure inside the deformation cavity 2, and is provided with a soft core fixing through hole 14-1, and a soft core bottom positioning boss 14-3 is provided at its bottom.

[0089] The outer mold structure 15 is composed of several outer mold structure units that are sealed and connected. Each outer mold structure unit is provided with an outer mold first positioning hole 15-1, an outer mold second positioning hole 15-2, and an outer mold structure protrusion 15-3. The outer mold first positioning hole 15-1 penetrates through the outer mold structure unit, and the outer mold second positioning hole 15-2 is used for positioning and connecting two adjacent outer mold structure units. The outer mold structure protrusion 15-3 protrudes inward and passes through the gap between adjacent soft cores 14 to contact the intermediate cavity mold 13. The gap between the outer mold structure protrusions 15-3 forms a reinforcing rib structure during casting, and the outer mold structure protrusions 15-3 form a reinforcing rib gap 11 after demolding.

[0090] The bottom cover mold 16 is provided with a bottom cover outer mold positioning hole 16-1, a bottom cover middle cavity mold positioning hole 16-2, a bottom cover soft core positioning groove 16-4, and a bottom cover soft core positioning hole 16-3; the bottom cover soft core positioning hole 16-3 is located inside the bottom cover soft core positioning groove 16-4; the bottom cover soft core positioning groove 16-4 cooperates with the soft core bottom positioning boss 14-3.

[0091] Figures 11 to 14 The mold assembly process is shown. (For example...) Figure 11 As shown, the intermediate cavity mold 13 is placed in the center of the bottom cover mold 16, and the positioning pin 18 is passed through the positioning hole 13-5 of the intermediate cavity mold to fix the intermediate cavity mold 13 and the bottom cover mold 16 to form an assembly.

[0092] like Figure 12 As shown, assemblies one are combined with an outer mold structure unit by placing the outer mold structure unit on the bottom cover mold 16 and passing the positioning pin 18 through the first positioning hole 15-1 of the outer mold to fix the outer mold structure unit to the bottom cover mold 16, thus forming assemblies two.

[0093] like Figure 13 As shown, the assembly 2 is combined with the soft core 14. The bottom positioning boss 14-3 of the soft core is placed in the soft core positioning groove 16-4 of the bottom cover, and the positioning post 18 is passed through the soft core fixing through hole 14-2 to fix the soft core to the bottom cover mold 16. Then, the other two soft cores 14 are fixed to the bottom cover mold 16 in sequence to form the assembly 3.

[0094] like Figure 14 As shown, assembly three is combined with top cover mold 12 and two other outer mold structural units to form assembly four, thus the mold assembly is successful. The positioning shaft 18, which passes through the positioning hole 13- of the middle cavity mold, will pass through the positioning hole 12-3 of the middle cavity mold of the top cover, and the positioning post 18, which passes through the soft core fixing through hole 14-2, will pass through the soft core positioning hole 12-2 of the top cover.

[0095] After assembling the mold to obtain assembly four, the entire mold needs to be sealed to prevent glue overflow. Then, silicone liquid or other fluid liquids can be poured through the top cover pouring hole 12-4. During the pouring process, due to the relatively complex mold structure, it is easy for liquid to be unable to enter the mold, which manifests as a higher internal pressure than the external air pressure, preventing the liquid from entering. Therefore, to solve this problem, some pouring overflow holes 12-1 need to be set at the top of the mold to ensure that the air inside the mold can be discharged in time and the liquid can enter completely. The pouring overflow holes 12-1 are distributed circumferentially around the mold, or they can be other shapes. As shown in the figure, there are 15 small pouring overflow holes 12-1. The number of pouring overflow holes 12-1 can also be set according to actual needs. The positioning post 18 passing through the top cover soft core positioning hole 12-2 can assemble and fix the soft core 14, the top cover mold 12, and the bottom cover mold 16 together. The positioning pin 18 passing through the positioning hole 12-3 of the top cover middle cavity mold is used to fix the middle cavity mold 13 together with the top cover mold 12 and the bottom cover mold 16.

[0096] Furthermore, an overflow limiting protrusion 12-5 is provided on the top cover mold 12, mainly to prevent excessive liquid overflow and to block part of the liquid, thus saving resources.

[0097] like Figure 16 The intermediate cavity mold 16 shown is mainly used to manufacture the inner bellows structure and to form the intermediate cavity 6. For ease of demolding, the intermediate cavity mold 16 can be divided into multiple assembled molds, such as... Figure 16 As shown, the structure can be divided into a single-cavity mold component 13-1, two-cavity mold components 13-2, six-cavity mold components 13-3, and a single-cavity mold component 13-4. The divided molds are then positioned using positioning pins 18 according to… Figure 16 The two structures are combined in the way shown in the right figure. In the figure, the positioning hole 13-5 of the middle cavity mold is the channel where the positioning shaft is located. This structure requires three positioning shafts for fixation. The pouring hole 13-6 of the middle cavity mold is the liquid pouring hole. This channel is a through structure, which can ensure that the liquid can flow from top to bottom through the pouring hole 13-6 of the middle cavity mold to the bottom overflow channel 13-7. As more liquid is injected, the pressure increases. The liquid will first pour the bottom of the mold, and then reach the top of the mold from bottom to top to complete the pouring.

[0098] The soft core 14 is the key design element of the mold involved in this embodiment. Unlike traditional casting and demolding, this patent application is the first to employ soft demolding technology. This involves specially treating the surface of the soft core material before placing it within a hard mold structure. The soft material refers to a material with certain tensile and bending deformation capabilities, capable of quickly returning to its original shape after bending. Common materials suitable for soft cores include: soft cores cast from silicone of a certain hardness, soft polymers, gelatin polymers, structures made of soft rubber and hydrogels, and structures made of PDMS. Paraffin wax or plaster should not be used as substitutes. The surface is then specially treated, such as by uniformly applying petroleum jelly, mineral oil or vegetable oil, talcum powder, or a release agent. It is important to note that only a thin layer of these materials should be applied to the soft core; excessive application can alter the chemical properties of the silicone or other soft materials. The release agent used is a water-based release agent, a polyurethane water-based release agent, or a lipid-based release agent. In this embodiment, petroleum jelly is chosen.

[0099] In this embodiment, a low-viscosity silicone material is used to manufacture the soft core, and a thin layer of petroleum jelly is evenly applied to the surface as a release agent. Furthermore, the overall temperature of the mold remains low during heating. Figure 17 The positioning post 18 is set in the through hole 14-1 of the soft core. During casting, the shaft needs to be placed in the mold and formed as one piece. Then, it can be pulled out after the silicone is completely cast and cured. The corrugated structure 14-2 matches the cavity structure in the deformation cavity 2. The positioning boss 14-3 at the bottom of the soft core is used to fix the soft core.

[0100] like Figure 18 The outer mold structure shown has two first positioning holes 15-1 on one outer mold structure unit. The positioning pins 18 inside these holes can pass through the top cover mold 12 and the bottom cover mold 16 for fixing. Bolts or similar materials can pass through the second positioning hole 15-2 to fix two adjacent outer mold structure units. The outer mold structure protrusion 15-3 can form reinforcing ribs 9 when combined with other molds.

[0101] The soft core used in this embodiment is cast using a soft core mold, such as... Figure 20 The shown soft core mold includes an upper soft core mold 17 and a lower soft core mold 19. The upper soft core mold 17 and the lower soft core mold 19 are assembled and fixed together, and then liquids such as silicone are poured in to form the soft core 14.

[0102] The upper mold 17 of the soft core is provided with a positioning hole 17-1, a pouring overflow hole 17-2, a positioning post through hole 17-3, and a pouring hole 17-4. The lower mold 19 of the soft core is provided with a positioning hole 19-1 and a positioning post through hole. The upper mold 17 and the lower mold 19 can be fixed together by a positioning shaft or bolt passing through the positioning holes 17-1 and 19-1. The pouring overflow hole 17-2 of the upper mold is used to promptly expel air from the mold.

[0103] In this embodiment, the materials used for the mold, excluding the soft core 14, are preferably materials with high temperature resistance, high strength, and the ability to be repeatedly molded, such as high-temperature photosensitive resin and ABS. If the requirements for silicone products are high, molds made of metal materials can also be used. When selecting the positioning pins 18, materials with high straightness and high hardness are preferred.

[0104] The software driver employs a soft demolding technology in its demolding design, which differs from traditional hard material demolding, paraffin wax demolding, plaster demolding, and 3D printing technology. This method is applicable to the processing of microchannels and precision devices, and can greatly improve production efficiency and reduce production costs.

[0105] This application is the first to use a soft material as the inner core for pouring silicone and other solutions and then demolding them, solving the molding problem of complex structures. It effectively avoids the low yield rate of silicone products caused by using traditional hard materials as mold cores, or using paraffin wax, plaster, etc. as inner cores, and can be used for large-scale production. The soft demolding technology in this invention application has the following advantages over traditional mold manufacturing and pouring methods:

[0106] (1) The first use of soft demolding technology can solve the casting problem of multi-layer complex structures. For example, the multi-layer corrugated soft actuator manufactured in this application cannot achieve integrated molding of multi-layer structures by conventional methods such as machine injection molding, or it cannot achieve integrated molding by other traditional casting methods. With this solution, not only can double-layer actuators with corrugated structures inside and out be produced, but also actuators with more layers can be produced, which can break through the manufacturing bottleneck of soft robots and generate new technological innovations.

[0107] (2) When using soft demolding technology, it is only necessary to prepare a soft mold core that is slightly smaller than the cavity structure size in advance. Then, place the soft mold core in the mold, assemble the mold, inject the fluid liquid into the mold, heat for a certain time or let it sit for a period of time until the liquid is completely solidified, and then remove the outer mold and the soft mold core in sequence. Among them, the soft mold core can be easily removed during the demolding stage because it has been specially treated in advance. The specific treatment method is to evenly coat the surface of the prepared soft mold core with a water-based release agent or a polyurethane water-based release agent, or some grease material. In this invention, Vaseline, which is commonly used in daily life, is used. A layer of Vaseline solvent is evenly coated on the surface of the soft mold core. Note that it should not be too much, otherwise the poured silicone liquid will not solidify; but it should not be too little either, and a certain ratio needs to be controlled, otherwise the soft core will stick to the silicone liquid. Here, Vaseline is mainly used to prevent the soft core from contacting the silicone liquid and to play a lubricating role.

[0108] (3) When using soft mold technology, it is particularly important to prepare a soft core similar to the cavity structure in advance. The size of the soft core should be determined according to the thickness of the soft actuator after casting. For example, if the thickness of the soft actuator after casting is required to be 2mm, the size of the soft core should be 2mm smaller than the overall cavity structure. Otherwise, the cast soft actuator will be uneven. The soft core can also be manufactured by mold casting. The soft core in this invention is cast from silicone with the same base. The Shore hardness of the silicone solution should be lower than the hardness of the cast soft actuator. Otherwise, it will be impossible to remove after casting. However, it should not be too high. If it is too high, the soft core will be too hard to be extracted from the mold. The soft core used in this invention application is cast from silicone with a Shore hardness of 20°. It can be removed after casting.

[0109] The specific implementation method for pouring is as follows:

[0110] (1) First, according to Figure 20 As shown, the mold for the soft core is assembled, and the soft core is poured. A low Shore hardness silicone liquid can be used for pouring, as needed. After pouring, the cured soft core is removed, as shown... Figure 17 It is a soft core structure that has already been cured.

[0111] (2) Secondly, the soft core is specially treated. In this invention, Vaseline is used to treat the surface of the soft core. Vaseline is evenly applied to the surface of the soft core.

[0112] (3) Next, the overall assembly of the software driver mold is carried out, such as... Figures 10-14 The molds are assembled sequentially. During the assembly of the soft core, that is... Figure 13 Be careful not to damage the petroleum jelly on the surface of the soft core.

[0113] (4) Finally, after the assembly of assembly four is completed, liquid is poured into it through the pouring hole. The present invention uses silicone liquid. After the pouring is completed, the mold inside can be taken out one by one.

[0114] The main methods for demolding are as follows:

[0115] (1) Once the casting is complete, the entire mold can be demolded. First, the outer mold structure 15 needs to be removed from the entire mold. There are a total of 3 outer molds, which need to be removed one by one.

[0116] (2) Then, remove the top cover mold 12 and the bottom cover mold 16, and pull out the positioning pin 18;

[0117] (3) Next, remove the middle cavity mold 13. Since the middle cavity mold 13 is a split type, it can be removed one by one.

[0118] (4) Finally, the soft core 14 is removed. This step is also a key part of the present invention. Figure 17 As can be seen, the soft core 14 has a bottom positioning boss 14-3, which ensures that the soft core can be fixedly positioned with the lower mold. Furthermore, after it is fixed to the bottom cover mold 16, when silicone liquid is poured, the bottom is non-corrugated, and the soft core is in complete contact with the lower surface of the bottom mold without gaps, preventing silicone liquid from entering. Therefore, the end face area of ​​the poured soft actuator is relatively large, making it easy to extract the soft core.

[0119] (5) After the soft core 14 is completely extracted, the end face of the soft core that has just been extracted can be sealed, thus completing the manufacturing process of a complete soft driver.

[0120] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An integrated multi-degree-of-freedom soft actuator, characterized by, The flexible material is integrally formed by flexible material, including a set number of deformation cavities, a reinforcing rib structure for connecting the deformation cavities, and an intermediate cavity surrounded by the deformation cavities and the reinforcing rib structure; The deformation cavity includes a plurality of deformation layers and gas holes arranged on end faces for airflow passing through; the deformation layer includes an outer layer bellows structure unit and an inner layer bellows structure unit, and a cavity structure between the two structure units; the reinforcing rib structure is composed of a plurality of reinforcing ribs, and the deformation layers between two horizontally adjacent deformation cavities are connected through the reinforcing ribs; there is a reinforcing rib gap between two adjacent reinforcing ribs; The outer layer bellows structure unit includes outer layer bellows troughs and outer layer bellows peaks; the inner layer bellows structure unit includes inner layer bellows troughs and inner layer bellows peaks; the end of the reinforcing rib is connected to the outer layer bellows structure unit and the inner layer bellows unit at the trough.

2. The integrated soft driver of claim 1, wherein, The flexible material is silica gel, hydrogel, gelatin or PDMS.

3. The integrated soft driver of claim 1, wherein, The peaks and / or troughs of the outer layer bellows structure unit and the inner layer bellows structure unit are in U shape, S shape, Ω shape or ∧ shape.

4. A mold for preparing an integrated multi-degree-of-freedom soft actuator, characterized by, It includes a top cover mold and a bottom cover mold, and an intermediate cavity mold, a soft core and an outer mold structure fixed between the top cover mold and the bottom cover mold; The soft core is arranged outside the intermediate cavity mold, and the outer mold structure is arranged outside the soft core to form a pouring forming cavity of the soft actuator; the surface of the soft core is coated with a release agent; The intermediate cavity mold is provided with an intermediate cavity mold pouring hole and an intermediate cavity mold positioning hole arranged along the axial direction thereof; the bottom of the intermediate cavity mold is provided with a bottom overflow channel in communication with the intermediate cavity mold pouring hole and the pouring forming cavity; The soft core is corrugated to match the cavity structure inside the deformation cavity, and is provided with a soft core fixing through hole, and the bottom is provided with a soft core bottom positioning boss; The outer mold structure is composed of a plurality of sealingly connected outer mold structure units, and the outer mold structure units are provided with an outer mold first positioning hole, an outer mold second positioning hole and an outer mold structure protrusion; the outer mold first positioning hole penetrates the outer mold structure unit, the outer mold second positioning hole is used for positioning and connecting two adjacent outer mold structure units; the outer mold structure protrusion protrudes inwardly and passes through the gap between the adjacent soft cores to contact the intermediate cavity mold.

5. A mold according to claim 4, wherein The top cover mold is provided with a top cover pouring hole, a top cover soft core positioning hole, a top cover intermediate cavity mold positioning hole and a pouring overflow hole; the top cover pouring hole is in communication with the intermediate cavity mold pouring hole.

6. A mold according to claim 5, wherein The top cover mold is also provided with an overflow limiting protrusion for blocking the overflowing pouring liquid.

7. A mold as defined in claim 4, wherein The bottom cover mold is provided with a bottom cover outer mold positioning hole, a bottom cover intermediate cavity mold positioning hole, a bottom cover soft core positioning groove and a bottom cover soft core positioning hole; the bottom cover soft core positioning hole is located in the bottom cover soft core positioning groove; the bottom cover soft core positioning groove cooperates with the soft core bottom positioning boss.

8. A mold according to claim 4, wherein The release agent is a water-based release agent or a lipid release agent.

9. A mold according to claim 8, wherein The water-based release agent is specifically a polyurethane water-based release agent.

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