A radial actuator for a peristaltic soft robot

Abstract

The present application relates to a kind of radial actuators for peristaltic soft robot, gas cavity, microchannel and cylindrical cavity are arranged in the radial actuator, cylindrical cavity is arranged along the central axis of radial actuator, gas cavity is annular and is arranged along the inner wall of radial actuator and keeps first preset distance with radial actuator, microchannel is arranged between gas cavity and the inner wall of radial actuator, gas cavity surrounds cylindrical cavity and the inner wall of gas cavity keeps second preset distance with the outer wall of cylindrical cavity, the air pressure in gas cavity can increase or decrease;Liquid metal is built-in in microchannel, when the air pressure in gas cavity changes when increasing, radial actuator occurs deformation and causes the deformation of microchannel, in turn, the resistance of liquid metal changes, and the expansion deformation condition of radial actuator is judged according to the resistance change of liquid metal.The expansion deformation performance of the present application improves radial actuator, so that it can be fixed displacement faster, improves the motion efficiency of peristaltic soft robot.

Description

Technical Field

[0001] This invention relates to the field of radial actuator design technology for soft robots, and in particular to a radial actuator for a peristaltic soft robot. Background Technology

[0002] In recent years, the field of soft robots has attracted widespread attention both at home and abroad. Among them, peristaltic soft robots have high adaptability in unstructured environments and can be widely used in various scenarios such as pipeline inspection and search in confined spaces. As an important factor determining motion efficiency, the radial actuator of peristaltic soft robots faces significant challenges in control and motion performance.

[0003] There are two main problems in the mechanical design of peristaltic soft robots. First, the excessive amount of gas input makes robot control challenging. Second, the robot's performance is low, making it unable to achieve the movement speed required for the robot's detection function.

[0004] In terms of control, soft robots are developing in areas such as integrated intelligent design and cutting-edge sensing technology. Wang combined electrically driven soft robots with smart materials through structural design, achieving multimodal functionality of the robot through shape reconstruction under external stimuli. Xu used a high-density dielectric elastomer actuator array as a soft peristaltic pump for the control and power source of fluid robots. However, peristaltic soft robots still rely on external sensing elements, such as pressure sensors placed near the air source rather than on the soft robot itself, when feeding back motion data. Although this semi-closed-loop control method is simple, external interference has a greater impact on sensor data, especially in complex environments. External sensors cannot provide accurate data feedback and have less sensitivity to actuator deformation, which is not conducive to the control of flexible materials in soft robots.

[0005] Regarding the motion performance of worm-like soft robots, scholars have also conducted research. Xiong proposed a hybrid actuator using multiple materials, called the MASH actuator, which combines electrostatic adhesion (EA) with gas actuation. It introduces an adaptive deformation constraint layer inspired by the longitudinal muscles of earthworms, which can change the length, stiffness, and position of the actuator, enhancing the robot's functionality. However, the different actuation methods also increase the complexity of control. Jiang proposed the design and fabrication of a worm-like soft robot designed for operation within pipes. It uses pneumatic actuators and origami-fabric composite materials, with paper serving as the robot's skeleton and fabric as its skin. The origami-like structural design gives the robot's soft actuator stronger mechanical properties. However, the origami-fabric composite material has poor compatibility with liquid conductive materials, hindering the achievement of an integrated actuator design. Liu proposed a modular bionic soft robot that can crawl and cross obstacles. The robot consists of multiple soft modules, each containing two parallel soft actuators. The gait of the bionic soft robot can be changed by controlling the shape of the two soft actuators, but it does not change the proportion of deformation time of the soft actuators, so the improvement on the robot's motion efficiency is relatively limited.

[0006] Soft robots consist of actuators, which can be driven in various ways, such as electrically, chemically, magnetically, thermally, and fluidically. The most common method is to use pressurized gas within different cavities to achieve movements such as expansion, contraction, torsion, or bending. This versatility makes soft robots widely used in many fields. The radial actuator of a peristaltic soft robot is a crucial factor determining its overall motion efficiency and control performance; however, current designs for radial actuators in peristaltic soft robots have not yielded significant results and urgently require improvement. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the fact that the design of radial actuators for peristaltic soft robots in the prior art has not been very effective.

[0008] To address the aforementioned technical problems, this invention provides a radial actuator for a peristaltic soft robot, wherein the radial actuator comprises an air cavity, a microchannel, and a cylindrical cavity, wherein...

[0009] The cylindrical cavity is arranged along the central axis of the radial actuator. The air chamber is annular and arranged along the inner wall of the radial actuator, maintaining a first preset distance from the radial actuator. The microchannel is disposed between the air chamber and the inner wall of the radial actuator. The air chamber surrounds the cylindrical cavity, and the inner wall of the air chamber maintains a second preset distance from the outer wall of the cylindrical cavity.

[0010] The air chamber is used to communicate with an air tube from outside the radial actuator, and the air pressure inside the air chamber is increased or decreased through the air tube outside the radial actuator; the cylindrical cavity is used to store the air tube that communicates with the air chambers of other radial actuators or axial actuators of the soft robot.

[0011] The microchannel contains liquid metal. When the air pressure in the gas chamber changes, the radial actuator deforms, causing the microchannel to deform as well. This deformation causes a change in the resistance of the liquid metal. The expansion and deformation of the radial actuator are determined based on the change in the resistance of the liquid metal.

[0012] In one embodiment of the present invention, the length of the major axis of the cross-section of the microchannel is assumed to be... The length of the minor axis is ,and , where the length of the major axis of the cross-section and minor axis length The ratio increases as the pressure inside the air chamber increases.

[0013] In one embodiment of the present invention, the microchannel cross-section includes circular and elliptical shapes. Under the same air pressure, the radial actuator exhibits greater expansion deformation in microchannels with elliptical cross-sections than in microchannels with circular cross-sections.

[0014] In one embodiment of the invention, the radial actuator, under the same air pressure, when the long axis length of the microchannel... With minor axis length When the ratio is within a preset range, if the length of the major axis is... With minor axis length The larger the ratio, the greater the degree of deformation of the microchannel and the greater the expansion deformation of the radial actuator sidewall.

[0015] In one embodiment of the present invention, when the major axis length of the microchannel cross-section is... equal to the length of the minor axis At a pressure range of 0-225 kPa, the resistance of the liquid metal in the microchannel increases with increasing pressure, and the rate of increase is... When the gas pressure is 225-300 kPa, the resistance of the liquid metal in the microchannel increases with increasing gas pressure, and the rate of increase is [missing value]. ,in, ;

[0016] When the length of the major axis of the microchannel cross-section Greater than the length of the minor axis At a pressure range of 0-225 kPa, the resistance of the liquid metal in the microchannel increases with increasing pressure, and the rate of increase is... When the gas pressure is 225-300 kPa, the resistance of the liquid metal in the microchannel increases with increasing gas pressure, and the rate of increase is [missing value]. ,in, ,and .

[0017] In one embodiment of the present invention, the radial actuator, under the same air pressure, is defined as having a major axis length of the microchannel cross-section. equal to the length of the minor axis Let the first sensitivity of the microchannel be GF1, and let the length of the major axis of the microchannel cross-section be... Greater than the length of the minor axis If the second sensitivity of the microchannel is GF2, then the second sensitivity GF2 is greater than the first sensitivity GF1. This sensitivity is used to reflect the radial expansion of the microchannel, and the formula is:

[0018] ;

[0019] in, For sensitivity, This represents the resistance during microchannel stretching. This represents the change in resistance. For external strain.

[0020] In one embodiment of the present invention, under the same air pressure, if other parameters of the radial actuator are the same, the thicker the annular air cavity, the greater the radial expansion deformation of the radial actuator.

[0021] In one embodiment of the present invention, during the deformation of the radial actuator, the pressure is assumed to be... The tension borne by the sidewall of the air cavity is The tensions borne by the upper and lower walls of the air cavity are respectively: The constraint force generated by fixing the interfaces at both ends of the radial actuator is The central cylindrical cavity sidewall is subject to constraint forces. Then the following conditions are met:

[0022] ;

[0023] ;

[0024] ;

[0025] ;

[0026] in, The radius of the circular cross-section of the radial actuator is... This is the distance between the air chamber and the inner wall of the radial actuator. The thickness of the air cavity. This represents the height of the air chamber.

[0027] In one embodiment of the present invention, the radial actuator is made of silicone.

[0028] The technical solution of the present invention has the following advantages compared with the prior art:

[0029] The radial actuator constructed in this invention reduces the constraint force on the radial actuator's expansion and deformation, improves the expansion and deformation performance of the radial actuator, enables it to fix the displacement more quickly under the same air pressure, shortens the transition time of the peristaltic soft robot's periodic motion, improves the motion efficiency of the peristaltic soft robot, and can change the output resistance after its own expansion and deformation, thereby realizing the fully flexible strain sensing function, which is beneficial for the precise control of the peristaltic soft robot's motion.

[0030] The present invention mainly improves the fixation of the peristaltic soft robot body by designing a cylindrical cavity in the radial actuator, so that the contraction of the radial actuator can better fix the body of the peristaltic soft robot. Attached Figure Description

[0031] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0032] Figure 1 This is a schematic diagram of the radial actuator microchannel design in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram showing the preliminary setting of the radial actuator structural parameters in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram showing the final setting of the radial actuator structural parameters in an embodiment of the present invention;

[0035] Figure 4 These are schematic diagrams illustrating the expansion and deformation of two different radial actuator structures in embodiments of the present invention.

[0036] Figure 5 This is a schematic diagram of the cross-section and mesh generation of the finite element model of the radial actuator in an embodiment of the present invention;

[0037] Figure 6(a) is a radial deformation displacement cloud diagram of the radial actuator at a pressure of 100 kPa when the microchannel parameters a=b=0.4 in the embodiment of the present invention.

[0038] Figure 6(b) is a radial deformation displacement cloud diagram of the radial actuator at a pressure of 200 kPa when the microchannel parameters a=b=0.4 in the embodiment of the present invention.

[0039] Figure 6(c) is a radial deformation displacement cloud diagram of the radial actuator at a pressure of 300 kPa when the microchannel parameters a=b=0.4 in the embodiment of the present invention.

[0040] Figure 7 This is a radial deformation displacement cloud diagram of the radial actuator under a pressure of 300 kPa when the microchannel parameters a=0.5 and b=1 in this embodiment of the invention.

[0041] Figure 8 This is a graph showing the relationship between the resistance and air pressure of microchannels with different structural parameters in an embodiment of the present invention;

[0042] Figure 9 This is a schematic diagram of the cross-section and mesh generation of the finite element model of the radial actuator with altered substrate structure in an embodiment of the present invention;

[0043] Figure 10(a) is a radial deformation displacement cloud diagram of the radial actuator in an embodiment of the present invention when the air cavity parameter d2=3mm;

[0044] Figure 10(b) is a radial deformation displacement cloud diagram of the radial actuator in an embodiment of the present invention when the air cavity parameter d2=3mm;

[0045] Figure 10(c) is a radial deformation displacement cloud diagram of the radial actuator in an embodiment of the present invention when the air chamber parameter d2=3mm;

[0046] Figure 11 This is a schematic diagram of the cross-section and mesh generation of the radial actuator finite element model obtained according to the structural parameters in Table 3 in this embodiment of the invention;

[0047] Figure 12(a) is a deformation displacement cloud diagram of the radial actuator with an annular air cavity in an embodiment of the present invention;

[0048] Figure 12(b) is a radial actuator deformation displacement cloud diagram of a common air cavity in an embodiment of the present invention;

[0049] Figure 13 This is a graph showing the relationship between the maximum displacement of the sidewall of the radial actuator and the air pressure in two different structures according to embodiments of the present invention.

[0050] Figure 14 This is a graph showing the relationship between the output resistance of the radial actuator and the amount of expansion deformation in an embodiment of the present invention. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0052] Example 1

[0053] Reference Figures 1-3As shown, this invention relates to a radial actuator for a peristaltic soft robot, wherein the radial actuator comprises an air chamber 1, a microchannel 2, and a cylindrical cavity 3, wherein...

[0054] The cylindrical cavity 3 is arranged along the central axis of the radial actuator. The air cavity 1 is annular and arranged along the inner wall of the radial actuator, maintaining a first preset distance from the radial actuator (the first preset distance can be used to place the microchannel 2) to form a first gap (the first gap is the same as the material of the radial actuator substrate, i.e., it is filled with silicone). The microchannel 2 is arranged between the air cavity 1 and the inner wall of the radial actuator. The air cavity 1 surrounds the cylindrical cavity 3, and the inner wall of the air cavity 1 maintains a second preset distance from the outer wall of the cylindrical cavity 3 (the second preset distance is actually to avoid the air cavity 1 from affecting the cylindrical cavity 3) to form a second gap (the second gap is the same as the material of the radial actuator substrate, i.e., it is filled with silicone).

[0055] The air chamber 1 is used to communicate with an air pipe from outside the radial actuator, and the air pressure inside the air chamber 1 is increased or decreased through the air pipe outside the radial actuator; the cylindrical cavity 3 is used to store the air pipe that communicates with the air chambers of other radial actuators or axial actuators of the soft robot.

[0056] The microchannel 2 contains liquid metal. When the air pressure in the enlarged air chamber 1 changes (increases or decreases), the radial actuator deforms (expands or contracts radially), causing the microchannel 2 to deform. The deformation of the microchannel 2 causes the resistance of the liquid metal to change. The expansion and deformation of the radial actuator is determined based on the change in the resistance of the liquid metal.

[0057] It should be noted that in this embodiment, both the air cavity 1 and the cylindrical cavity 3 are actually connected to the radial actuator substrate. Both the air cavity 1 and the cylindrical cavity 3 are formed within the radial actuator substrate. That is, the gaps corresponding to the first and second preset distances mentioned above are filled with silicone of the same material as the radial actuator substrate.

[0058] Furthermore, let the length of the major axis of the cross-section of the microchannel 2 be... The length of the minor axis is ,and , where the length of the major axis of the cross-section and minor axis length The ratio increases as the pressure inside the air chamber 1 increases.

[0059] Furthermore, the cross-section of the microchannel 2 includes circular and elliptical shapes. Under the same air pressure, the radial actuator with an elliptical cross-section has a greater expansion deformation than the microchannel 2 with a circular cross-section.

[0060] Furthermore, under the same air pressure, the radial actuator, when the major axis length of microchannel 2... With minor axis length When the ratio is within a preset range, if the length of the major axis is... With minor axis length The larger the ratio, the higher the degree of deformation of the microchannel 2, and the greater the expansion deformation of the radial actuator sidewall.

[0061] Furthermore, when the major axis length of the cross-section of the microchannel 2 is... equal to the length of the minor axis At a pressure of 0-225 kPa, the resistance of the liquid metal in the microchannel 2 increases with increasing pressure, and the rate of increase is... When the gas pressure is 225-300 kPa, the resistance of the liquid metal in the microchannel 2 increases with increasing gas pressure, and the growth rate is [missing value]. ,in, ;

[0062] When the major axis length of the cross-section of the microchannel 2 Greater than the length of the minor axis At a pressure of 0-225 kPa, the resistance of the liquid metal in the microchannel 2 increases with increasing pressure, and the rate of increase is... When the gas pressure is 225-300 kPa, the resistance of the liquid metal in the microchannel 2 increases with increasing gas pressure, and the growth rate is [missing value]. ,in, ,and .

[0063] Furthermore, under the same air pressure, the radial actuator is defined by the length of the major axis of the cross-section of the microchannel 2. equal to the length of the minor axis Let the first sensitivity of microchannel 2 be GF1, and let the length of the major axis of the cross-section of microchannel 2 be... Greater than the length of the minor axis The second sensitivity of microchannel 2 is GF2, which is greater than the first sensitivity GF1. This sensitivity is used to reflect the radial expansion of microchannel 2, and the formula is:

[0064]

[0065] in, For sensitivity, This represents the resistance during microchannel stretching. This represents the change in resistance. For external strain.

[0066] Furthermore, under the same air pressure, if the other parameters of the radial actuator are the same, the thicker the annular air cavity 1 is, the greater the radial expansion deformation of the radial actuator.

[0067] The following is a detailed description of this embodiment:

[0068] The peristaltic soft robot mainly consists of a radial actuator, an axial actuator, a trachea, and fiber-reinforced wires or helical tubes wound around the surface of the axial actuator. The radial actuator body is modeled after an annelid, and its mechanical design is inspired by the symmetrical cylindrical part of the annelid's body cavity. The radial actuator is made of super-elastic silicone, which can expand radially under air pressure. When it expands to the inner wall of the trachea, it can fix the soft robot. In this embodiment, a sensing layer (i.e., microchannel 2) is introduced and liquid metal is injected to give the radial actuator strain sensing function while maintaining its overall flexibility. The design of the radial actuator microchannel 2 is as follows: Figure 1 As shown, the microchannel 2 is also provided with positive and negative electrode connections. Both positive and negative electrodes extend from the inner wall of the radial actuator to the outside of the radial actuator between the inner wall of the radial actuator and the outer wall of the gas chamber 1, and are connected to the controller outside the axial actuator for detecting the resistance of the liquid metal in the microchannel 2.

[0069] When the air pressure in the radial actuator's air chamber 1 is increased, the actuator expands radially, and the microchannel 2 is also stretched and deformed. Due to the incompressibility of the liquid, the shape of the liquid metal inside the microchannel 2 will change accordingly, and the resistance of the liquid metal will also change with the change in shape. The preliminary structural parameters of the radial actuator are set as follows: Figure 2 As shown, and These represent the minor axis length and major axis length of the cross-section of microchannel 2, respectively. This is the distance between the outer wall of air chamber 1 and the inner wall of the radial actuator. The thickness of air cavity 1, The height of air chamber 1, The length of microchannel 2 The length of the radial actuator, Let be the radius of the circular cross-section of the radial actuator.

[0070] The resistance change of microchannel 2 in the radial actuator of this embodiment The theoretical relationship between it and its deformation is as follows:

[0071] (1)

[0072] In the formula, and The resistances of the radial actuator under microchannel stretching and without deformation are respectively. It is the resistivity of liquid metal. This represents the original length of the microchannel. To apply external strain, and These represent the minor axis length and major axis length of the microchannel cross-section, respectively. These represent the deformation amounts of the minor and major axes, respectively. From equation (1), it can be seen that, given the material of microchannel 2, the resistance value of microchannel 2 depends entirely on its original length. The minor axis length of the cross-section of microchannel 2 and major axis length When the radial actuator expands, the length of microchannel 2 increases and the cross-sectional area decreases, resulting in an increase in the resistance of the liquid metal within microchannel 2. After the radial actuator is released, microchannel 2 returns to its original geometry, and the elastic force pushes the liquid back, causing the resistance of the liquid metal to decrease. Therefore, the expansion and deformation of the radial actuator can be determined by observing the resistance change of microchannel 2.

[0073] Peristaltic soft robots require gas pressurization for propulsion, and controlling different time states necessitates adjusting the pressure in each air chamber. Therefore, the connection interfaces between the radial actuator and components such as the air tube and axial actuator are made of rubber with low elasticity and good airtightness to reduce the impact of hyperelastic actuator deformation on the air tube. However, the top and bottom of the radial actuator are constrained by different interfaces, causing stress to concentrate in the middle of the actuator. This results in greater strain in the middle than at the ends, making the deformation performance of the middle part of the radial actuator a major factor affecting its fixation to the inner wall of the pipe after radial expansion.

[0074] To improve the deformation performance of the radial actuator, a complete radial actuator structure was designed, incorporating the aforementioned microchannel 2, as shown below. Figure 3 As shown, the air chamber 1 is annular along the inner wall of the radial actuator, surrounding the central cylindrical cavity 3. The central cylindrical cavity 3 is integrated with the connection interface and made of the same material. The air tube is fixed inside the cylindrical cavity 3 through the connection interface, while the gas is diverted, reducing the fixed interface range at both ends of the radial actuator.

[0075] Figure 4 The expansion and deformation principles of two radial actuator structures were compared. Figure 4 (a) is a schematic diagram of the expansion and deformation of a radial actuator with a conventional air cavity. Figure 4 (b) is a schematic diagram of the expansion deformation of a radial actuator with an outer ring air cavity.

[0076] exist Figure 4 During the radial actuator deformation process shown in (a), the pressure is assumed to be... The tension on the sidewalls of the air cavity is The tensions borne by the upper and lower walls of the air cavity are respectively: The constraint force generated by fixing the interfaces at both ends of the radial actuator is The radial actuator sidewall is subject to constraint forces at both ends. Pressurizing the air chamber of the radial actuator results in the following force balance relationship:

[0077] (2)

[0078] (3)

[0079] (4)

[0080] (5)

[0081] From formulas (2)-(5), it can be seen that as air pressure increases, and Both will increase in size, in order to maintain balance, , This also increases accordingly. At this point, the radial actuator does not undergo material deformation, while when , After increasing each constraint to its upper limit, only tension remains. and It continues to increase as air pressure increases, at this point , The sidewalls of the actuator begin to extend axially and tend to expand under pressure, with the degree of expansion increasing as pressure decreases. and It is enhanced as the difference between them increases.

[0082] Therefore, under the same material parameters and air pressure conditions, reducing the constraint force The upper limit or increase the tension It can enhance the radial expansion deformation performance of the radial actuator and improve its deformation efficiency.

[0083] exist Figure 4 (b) shows the radial actuator deformation process, assuming the pressure is... The tension on the sidewall of air chamber 1 is The tensions borne by the upper and lower walls of air cavity 1 are respectively: The constraint force generated by fixing the interfaces at both ends of the radial actuator is ,and Figure 4 Compared to (a), where the constraint force is concentrated at both ends of the radial actuator's axial direction, this approach is more effective. Figure 4(b) The range of the constraint force decreases as the range of the fixed interface shrinks, concentrating at both ends of the central cylindrical cavity 3. This removes the constraint force on the radial actuator sidewalls, while the constraint force on the central cylindrical cavity 3 sidewalls is... Because the central cylindrical cavity 3 uses the same material as the connecting interface, it is a rubber-like material with low elasticity and good airtightness. Pressurizing the annular air chamber 1 of the radial actuator achieves the following force balance:

[0084] (6)

[0085] (7)

[0086] (8)

[0087] (9)

[0088] in, The radius of the circular cross-section of the radial actuator is... This is the distance between the air chamber and the inner wall of the radial actuator. The thickness of the air cavity. Let be the height of the air chamber. From formulas (6)-(9), it is found that when... and When the pressure increases with increasing air pressure, in order to maintain balance, , It also increases accordingly, and Figure 4 (a) The difference is that, Figure 4 (b) The constraint force of the two ends of the radial actuator on its sidewalls. The effective range has shifted to the sidewall of the central cylindrical cavity 3, significantly reducing the resistance experienced by the radial actuator sidewall during deformation and improving the radial expansion deformation performance of the actuator. Meanwhile, the sidewall of the central cylindrical cavity 3 is fixed to the two end connection interfaces 4 and has low material elasticity, resulting in limited constraint force. The upper limit is relatively high. The sidewalls of the central cylindrical cavity 3 do not deform with the increase of air pressure. This is because the force balance process of the radial actuator sidewall before material deformation is shortened. The radial actuator sidewall changes with tension. The increase ratio Figure 4 (a) allows the radial actuator to reach the deformation state more quickly, thereby improving the expansion and deformation efficiency of the radial actuator.

[0089] The experimental analysis is as follows:

[0090] This embodiment uses COMSOL finite element simulation software to analyze the effects of different structural parameters on the strain sensing effect of the radial actuator microchannel 2 and on the expansion and deformation performance of the radial actuator. To simplify the simulation, details such as electrodes, air pipes, and interfaces are simplified. Material parameters are set, with the density of the silicone substrate for the radial actuator being 2400 kg / m³. 3 The elastic modulus is 1.8 MPa, and the density of the liquid metal is 6280 kg / m³. 3 The dynamic viscosity is 0.002 Pa·s, and the resistivity is 2.94 × 10⁻⁶. -7 By setting different structural parameters (Ω / m), the deformation of the actuator's radial expansion and the state of the microchannel cross-section are obtained through multiphysics simulation of fluid-structure interaction. The simulation results are compared and analyzed to optimize the design parameters.

[0091] With structural parameters set as H=12mm, h=10mm, R=7.5mm, r=6.5mm, and L=7π, the cross-sectional parameters of microchannel 2 were varied. With microchannel cross-sectional parameters The numerical values ​​were used to initially establish a finite element model of the radial actuator containing microchannel 2 and perform mesh generation. See details below. Figure 5 The current terminal and ground were respectively set at the boundary sections at both ends of microchannel 2, and the voltage was set to 1V. The sensing performance of microchannel 2 with different cross-sectional parameters on the radial expansion strain of the actuator was studied.

[0092] Finite element simulations were performed on the microchannel 2 of the radial actuator with different structures. Figure 6 shows the radial deformation displacement cloud map of the radial actuator under different pressures when the parameters a=b=0.4mm. By comparing Figure 6(a), Figure 6(b) and Figure 6(c), it can be seen that the expansion deformation of the actuator sidewall increases with the increase of air pressure. The cross-sectional state of the microchannel 2 also changes with the pressure. In the radial direction, as the pressure increases, the cross-section of the microchannel 2 is compressed, thus reducing the short axis length. In the axial direction, as the pressure increases, the cross-section of the microchannel 2 increases the long axis length due to the stretching of the radial actuator sidewall. Figure 7 For the parameters a=0.5 and b=1, the deformation contour map of microchannel 2 at P=300kPa is compared with Figure 6(c). Figure 7 The microchannel 2 exhibits a higher degree of compression and stretching deformation, and the actuator sidewall also undergoes greater expansion deformation.

[0093] Figure 8is a graph showing the relationship that the resistance of microchannels 2 with different structures changes with the increase of air pressure. In the graph, the resistance value of microchannel 2 increases non-linearly with the increase of pressure. Within a certain pressure range, the resistance value increases slowly, but when the pressure increases beyond a certain range, the cross-section of microchannel 2 will undergo relatively obvious deformation. Moreover, when the length of the major axis of the cross-section of microchannel 2 is greater than the length of the minor axis, the deformation degree is higher, which has a greater impact on the resistance, that is, when a < b, the non-linear relationship between the resistance value and the pressure is more obvious, and the resistance increases by a larger extent under the same pressure.

[0094] This example analyzes the radial expansion strain sensing performance of the actuator microchannel 2 through the sensitivity (GF), and the GF of microchannel 2 can be calculated according to formula (10):

[0095] (10)

[0096] In formula (10), represents the resistance when the microchannel is stretched, represents the resistance change amount. The higher the GF value, the more sensitive the microchannel 2 is to the expansion strain. The relevant data of the strain of microchannels 2 with different structures under the same air pressure are shown in Table 1.

[0097] In Table 1, the lengths of the minor axis of the cross-section of the 1st group, the 2nd group, the 3rd group, the 4th group, and the 5th group are all equal to the lengths of the major axis of the cross-section. A comparison between them shows that when a = b, the deformation amount and sensitivity of microchannel 2 do not change significantly with different cross-section lengths. The lengths of the major axis of the cross-section of the 6th group and the 7th group are both greater than the lengths of the minor axis of the cross-section, and the sensitivity is significantly improved compared with the previous five groups, indicating that the cross-sectional shape of the microchannel has a great influence on the sensing performance of the actuator microchannel 2. When the length of the major axis of the cross-section is greater than the length of the minor axis of the cross-section and the proportion of the cross-sectional shape is appropriate, the sensing performance of the radial actuator microchannel 2 can be improved to a certain extent. Therefore, the parameter data of the 6th group with the highest sensitivity is selected.

[0098] Table 1 Strain data of microchannels with different structures under the action of the same air pressure

[0099]

[0100] The structural parameters are set as H=12mm, h=10mm, R=7.5mm, L=7π, a=b=0.4mm, =1mm, the radius of the central cylindrical cavity 3 is changed, that is, the parameter is changed , the finite element model of the radial actuator is established and meshed as shown in Figure 9 shown. The current terminal and the ground are respectively set at the boundary sections at both ends of microchannel 2, the voltage is set to 1V, and the influence of different matrix structures on the radial expansion deformation performance of the actuator is studied.

[0101] Figure 10 shows the effect of changing only parameters under the same pressure. The displacement cloud diagram of the radial actuator substrate was obtained at that time. The deformation and strain results of the radial actuator are shown in Table 2. Comparing Figure 10 with Figure 6(c) with the same pressure and the same structural parameters of the radial actuator microchannel 2, it was found that the expansion deformation of the radial actuator in Figure 10 was greater than that in Figure 6(c). Comparing the three sets of data in Table 2 with the third set of data in Table 1, it was found that when the overall size of the actuator and the structure of the microchannel 2 were the same, the radial actuator with the annular air cavity 1 had a larger strain than the ordinary radial actuator. The annular air cavity 1 can improve the deformation performance of the radial actuator substrate. In Table 2, the strain of radial actuators with different structures increased as the radius of the central cylindrical cavity 3 decreased. This indicates that under the same conditions, the constraint force decreased as the radius of the central cylindrical cavity 3 decreased, which enhanced the radial expansion deformation performance of the radial actuator substrate. Therefore, the selected parameters... =5mm radial actuator substrate structure.

[0102] Table 2 Deformation results of radial actuators with different matrix structures

[0103]

[0104] Based on the foregoing, this embodiment ultimately selects the structural parameters of the radial actuator shown in Table 3 to establish the final design model and divide the mesh as follows: Figure 11 As shown, the expansion and deformation effects of a radial actuator with a conventional structure and the radial actuator designed in this embodiment are compared and analyzed using finite element simulation under the same material.

[0105] Table 3 Structural parameters of radial actuators (unit: mm)

[0106]

[0107] Figure 12 shows the deformation displacement cloud diagrams of the radial actuators with two structures at P=300kPa. The maximum displacement of the radial actuator sidewall with the annular air cavity 1 is 2.18mm, and the strain is 29.1%. The maximum displacement of the radial actuator sidewall with the ordinary air cavity is 1.67mm, and the strain is 22.3%. The relationship between the maximum displacement of the radial actuator sidewall and the air pressure for the two structures is as follows: Figure 13 As shown in the figure, under the same air pressure, the expansion and deformation performance of the radial actuator with a circular air chamber 1 is significantly higher than that of a conventional radial actuator with an air chamber, and the difference increases with increasing air pressure. Furthermore, the addition of microchannel 2 eliminates the need for external sensors to provide feedback on the actuator's deformation state. The relationship between the output resistance of the radial actuator and the amount of expansion and deformation is shown in the figure. Figure 14 As shown, it can complete the fully flexible sensing of the radial actuator expansion and deformation process.

[0108] The radial actuator constructed in this invention reduces the constraint force on the radial actuator's expansion and deformation, improves the expansion and deformation performance of the radial actuator, enables it to fix displacement more quickly under the same air pressure, shortens the transition time of the peristaltic soft robot's periodic motion, improves the motion efficiency of the peristaltic soft robot, and can change the output resistance after its own expansion and deformation, thereby realizing a fully flexible strain sensing function, which is beneficial for the precise control of the peristaltic soft robot's motion.

[0109] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0110] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A radial actuator for a peristaltic soft robot, characterized in that: The radial actuator is provided with an air chamber (1), a microchannel (2), and a cylindrical cavity (3), wherein, The cylindrical cavity (3) is arranged along the central axis of the radial actuator. The air chamber (1) is annular and arranged along the inner wall of the radial actuator, maintaining a first preset distance from the radial actuator. The microchannel (2) is arranged between the air chamber (1) and the inner wall of the radial actuator. The air chamber (1) surrounds the cylindrical cavity (3), and the inner wall of the air chamber (1) maintains a second preset distance from the outer wall of the cylindrical cavity (3). The air chamber (1) is used to communicate with an air pipe from outside the radial actuator, and the air pressure inside the air chamber (1) is increased or decreased through the air pipe outside the radial actuator; the cylindrical cavity (3) is used to store the air pipe that communicates with the air chambers of other radial actuators or axial actuators of the soft robot. The microchannel (2) contains liquid metal. When the air pressure in the gas chamber (1) changes, the radial actuator deforms, causing the microchannel (2) to deform. The deformation of the microchannel (2) causes the resistance of the liquid metal to change. The expansion and deformation of the radial actuator is judged based on the change in the resistance of the liquid metal.

2. The radial actuator for a peristaltic soft robot according to claim 1, characterized in that: Let the length of the major axis of the cross-section of the microchannel (2) be... The length of the minor axis is ,and , where the length of the major axis of the cross-section and minor axis length The ratio increases as the pressure inside the air chamber (1) increases.

3. The radial actuator for a peristaltic soft robot according to claim 1, characterized in that: The microchannel (2) has a circular or elliptical cross-section. Under the same air pressure, the radial actuator has a greater expansion deformation of the microchannel (2) with an elliptical cross-section than that with a circular cross-section.

4. The radial actuator for a peristaltic soft robot according to claim 1, characterized in that: Under the same air pressure, the radial actuator, when the major axis length of the microchannel (2) is... With minor axis length When the ratio is within a preset range, if the length of the major axis is... With minor axis length The larger the ratio, the higher the degree of deformation of the microchannel (2) and the greater the expansion deformation of the radial actuator sidewall.

5. The radial actuator for a peristaltic soft robot according to claim 1, characterized in that: When the length of the major axis of the cross-section of the microchannel (2) equal to the length of the minor axis At a pressure of 0-225 kPa, the resistance of the liquid metal in the microchannel (2) increases with increasing pressure, and the growth rate is... When the gas pressure is 225-300 kPa, the resistance of the liquid metal in the microchannel (2) increases with the increase of gas pressure, and the growth rate is... ,in, ; When the length of the major axis of the cross-section of the microchannel (2) Greater than the length of the minor axis At a pressure of 0-225 kPa, the resistance of the liquid metal in the microchannel (2) increases with increasing pressure, and the growth rate is... When the gas pressure is 225-300 kPa, the resistance of the liquid metal in the microchannel (2) increases with the increase of gas pressure, and the growth rate is... ,in, ,and .

6. The radial actuator for a peristaltic soft robot according to claim 1, characterized in that: Under the same air pressure, let the length of the major axis of the cross-section of the microchannel (2) be... equal to the length of the minor axis The first sensitivity of the microchannel (2) is GF1, and the length of the major axis of the cross-section of the microchannel (2) is given. Greater than the length of the minor axis The second sensitivity of the microchannel (2) is GF2, which is greater than the first sensitivity GF1. The sensitivity is used to reflect the radial expansion of the microchannel (2), and the formula is: ； in, For sensitivity, This represents the resistance during microchannel stretching. This represents the change in resistance. For external strain.

7. The radial actuator for a peristaltic soft robot according to claim 1, characterized in that: Under the same air pressure, if the other parameters of the radial actuator are the same, the thicker the annular air cavity (1), the greater the radial expansion deformation of the radial actuator.

8. The radial actuator for a peristaltic soft robot according to claim 1, characterized in that: During the radial actuator deformation process, assuming the pressure is... The tension borne by the sidewall of the air cavity is The tensions borne by the upper and lower walls of the air cavity are respectively: The constraint force generated by fixing the interfaces at both ends of the radial actuator is The central cylindrical cavity sidewall is subject to constraint forces. Then the following conditions are met: ； ； ； ； in, The radius of the circular cross-section of the radial actuator is... This is the distance between the air chamber and the inner wall of the radial actuator. The thickness of the air cavity. This represents the height of the air chamber.

9. The radial actuator for a peristaltic soft robot according to claim 1, characterized in that: The radial actuator is made of silicone.

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