Starfish-imitating type pipe foot and soft robot supporting and walking mechanism adopting pipe foot

Abstract

The invention relates to the technical field of soft robots, in particular to a starfish-imitating pipe foot and a soft robot supporting and walking mechanism adopting the pipe foot. The soft robot adopts a plurality of starfish-imitating pipe feet which are telescopic in the axial direction as basic driving units, the starfish-imitating pipe feet are made of soft materials, woven mesh pipes are embedded in the starfish-imitating pipe feet, and large-stroke axial extension and elastic contraction are achieved under the condition that radial expansion deformation is limited by applying and releasing air pressure to pneumatic connectors. A plurality of starfish-imitating type pipe feet are arranged in a linear array mode, and the telescopic time sequence of each starfish-imitating type pipe foot is controlled through an air source and an electromagnetic valve, so that a soft robot device is formed and is suitable for multi-mode motion on a plane or a complex terrain. According to the invention, the structure is compact, the driving and the control are simple, the flexible support and the pneumatic telescopic function of the bionic starfish pipe foot are effectively integrated, and the environmental adaptability and the module universality are obviously improved.

Description

Technical Field

[0001] This invention relates to the field of soft robot technology, specifically to a starfish-like tubular foot and a soft robot walking mechanism using the tubular foot. Background Technology

[0002] Soft robots have garnered widespread attention for their high environmental adaptability and safety in scenarios such as exploration, rescue, medical treatment, grasping, and operations in complex environments. Many organisms in nature rely on localized extension and contraction and multi-legged coordination to achieve stable movement and adapt to complex terrains. For example, the tube feet of marine echinoderms are radially distributed, enabling them to generate propulsion through flexible extension and contraction and adapt to irregular surfaces. Existing related technologies typically employ multiple independent flexible actuators and complex support structures to achieve multi-point support and propulsion, resulting in problems such as diverse actuator types, complex pneumatic circuits, large overall system size, and heavy control and energy consumption burdens. Many solutions struggle to achieve an integrated design of "large-stroke extension + flexible support" within a single module, hindering the reusability of standardized modules. Therefore, it is necessary to provide a compact, simple-to-drive starfish-inspired tube foot design that, under conditions of limited volume and pneumatic circuitry, can achieve large-stroke aerodynamic extension and contraction capabilities through reasonable structural design, enabling soft robots to perform multimodal motion on planar surfaces and complex terrains. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a starfish-like tubular foot and a soft robot support and walking mechanism using this tubular foot.

[0004] One of the above-mentioned objectives of the present invention is achieved by the following technical solution: A starfish-like tube foot comprises a columnar body and a braided mesh tube embedded within the columnar body. The columnar body is made of a soft material that can elastically deform under stress. One end of the columnar body is the ground-contact end, and an axial ventilation blind hole is provided at the center of the columnar body. The other end of the columnar body is provided with a pneumatic interface for connecting to an external air source to allow gas to be introduced into the ventilation blind hole. The braided mesh tube is coaxially embedded in the outer periphery of the ventilation blind hole within the columnar body in a pre-compressed state along the axial direction. The braided mesh tube is used to constrain the radial expansion deformation of the tube foot and guide its axial elongation when gas is introduced into the ventilation blind hole. By applying air pressure to the pneumatic interface, the starfish-like tube foot is driven to produce axial elongation movement. After depressurization, the tube foot automatically retracts and returns to its original position under the elastic action of the braided mesh tube and the columnar body.

[0005] Moreover, the columnar body is made of polydimethylsiloxane (PDMS), polyurethane (PU), hydrogel, natural rubber, vulcanized rubber, or silicone rubber.

[0006] Furthermore, the method for manufacturing the starfish-like tube foot includes the following steps: Step 1: Cut a piece of braided mesh tube of suitable length, which should be less than the designed tube length; then insert two rings into the two ends of the braided mesh tube respectively, and glue and fix them to the two ends of the braided mesh tube to form a braided mesh tube assembly; Step 2: Then, the braided mesh tube assembly is axially pre-compressed and positioned in the forming mold of the tube foot. The forming material of the columnar body is poured into the mold, so that the braided mesh tube is poured into the columnar body to form a starfish-like tube foot.

[0007] The second objective of this invention is achieved through the following technical solution: A soft robot support and walking mechanism using the above-mentioned starfish-like tubular feet includes multiple sets of tubular foot units arranged in a horizontal and vertical array fixed to the bottom of the robot body. Each set of tubular foot units consists of multiple tubular feet evenly distributed in the circumferential direction, and the tubular feet are inclined to the bottom of the robot body.

[0008] Moreover, each set of foot units consists of four feet.

[0009] Moreover, according to a predetermined gait sequence, air pressure is applied or released to the pneumatic interface of at least one starfish-like tube foot, driving the starfish-like tube foot to extend or retract, thereby enabling the robot body to move in a directional manner relative to the ground.

[0010] Moreover, during gait control, the amount of extension and contraction and the output force of the starfish-like tubular foot are precisely controlled by adjusting the magnitude and duration of the air pressure applied to the pneumatic interface.

[0011] The advantages and positive effects of this invention are as follows: 1. This invention highly integrates pneumatic telescopic function into a single flexible starfish-like tube foot. At the same time, through the structural design of "braided mesh radial constraint + axial pre-compression", the starfish-like tube foot can still obtain a large axial telescopic stroke with a small diameter. Moreover, the output force and telescopic amount can be adjusted by air pressure and pre-compression parameters to adapt to different load and motion requirements.

[0012] 2. Compared with traditional pneumatic artificial muscles, the starfish-like tubular feet of this invention integrate flexible support structure and pneumatic drive function into one, with a more compact structure, significantly improving the overall motion coordination. It does not require an additional rigid skeleton or complex connection mechanism. While achieving the same telescopic function, it significantly simplifies the overall configuration of the soft robot, reduces system complexity and assembly difficulty, and makes it easier to achieve multi-unit, high-density integrated arrangement.

[0013] 3. The soft robot based on the starfish-like tubular foot design can achieve multi-directional movement, which improves the mobility and environmental adaptability of the soft robot in narrow spaces and complex terrains. In addition, the main body of the starfish-like tubular foot, including the ground contact end, is made of flexible material, which can produce conforming deformation on uneven or curved surfaces, increasing the contact area and improving support and friction performance.

[0014] 4. The invention features a starfish-like tube foot combined with a centralized air source and an independent control method for the solenoid valve array. This allows for the coordinated and sequential driving of multiple starfish-like tube feet. The number and arrangement of the tube foot structure can be flexibly expanded according to task requirements, exhibiting excellent modular expansion capability and reusability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the starfish-like tube foot structure of the present invention; (a) is a connection diagram of the two end rings and the braided mesh tube, (b) is a schematic diagram of the external appearance of the tube foot, and (c) is a schematic diagram of the internal structure of the tube foot; Figure 2 This is a schematic diagram of the starfish-like tube foot of the present invention under support and elongation; (a) is a schematic diagram of the support state, and (b) is a schematic diagram of the elongation state. Figure 3 This is a structural diagram of a soft robot based on a starfish-like tubular foot design. Figure 4 This is a schematic diagram of a soft robot based on a starfish-like tube foot design in a standing position. Figure 5 (a) is a schematic diagram of the first embodiment of the present invention during the linear walking motion process; (b) is a schematic diagram of the soft robot moving in the direction of the arrow after one motion cycle in a standing state; (c) is a schematic diagram of the position change of the soft robot in one motion cycle as viewed from above.

[0016] Figure 6 This is a schematic diagram of the second embodiment of the present invention during the linear walking motion process; (a) is a schematic diagram of the soft robot moving in the direction of the arrow after one motion cycle in a standing state, and (b) is a schematic diagram of the position change of the soft robot in one motion cycle as viewed from above.

[0017] Figure 7 This is a schematic diagram illustrating the process of the soft robot of the present invention performing a reversing motion; Figure 8 This is a schematic diagram of the movement of the soft robot of the present invention through a curved channel; Figure 9 This is a physical image of the braided mesh tube that can be used in this invention. Detailed Implementation

[0018] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.

[0019] A starfish-like tube foot, please see Figures 1-8 The starfish-like tube foot consists of a columnar body 103 and a braided mesh tube 102 embedded within the columnar body. The braided mesh tube is made of aramid, polyester, or other materials. The columnar body is made of a soft material that can undergo elastic deformation under stress, such as polydimethylsiloxane (PDMS), polyurethane (PU), hydrogel, natural rubber, vulcanized rubber, or silicone rubber. One end of the columnar body is the ground contact end, and an axial ventilation blind hole 105 is provided at the center of the columnar body. The other end of the columnar body is provided with a pneumatic interface 104 for connecting to an external air source to allow gas to be introduced into the ventilation blind hole. The braided mesh tube is coaxially embedded in the periphery of the ventilation blind hole within the columnar body in a pre-compressed state along the axial direction. The braided mesh tube is used to constrain the radial expansion deformation of the tube foot and guide its axial elongation when gas is introduced into the ventilation blind hole. By applying air pressure to the pneumatic interface, the starfish-shaped tube foot is driven to generate axial elongation. After depressurization, it automatically contracts and resets under the elastic action of the braided mesh tube and the columnar body.

[0020] This starfish-shaped tube can be manufactured using the following method: Step 1: Cut a suitable length of braided mesh tube 102, the length of which should be less than the designed tube length; then insert two rings 101 into the two ends of the braided mesh tube respectively, and glue and fix them to the two ends of the braided mesh tube to form a braided mesh tube assembly. In this embodiment, the rings are printed by a 3D printer using PLA printing material, which is a type of 3D printing consumable based on polylactic acid (PLA).

[0021] Step 2: Then, the braided mesh assembly is axially pre-compressed and positioned in the forming mold of the tube foot. The molding material for the columnar main body is then poured into the mold, allowing the braided mesh to be cast into the columnar main body. See the diagram for the structure after casting. Figure 1 (b) in the text, see internal structure. Figure 1 (c) in the middle.

[0022] A schematic diagram of the starfish-like tube foot under support and elongation is shown below. Figure 2 As shown, Figure 2 (a) When the input air pressure is low, the elongation of the starfish-shaped tube foot is small, but the stiffness is significantly improved compared to the pressureless state, mainly serving as a structural support. That is, the supported state, with a length of L0. Figure 2(b) When the input air pressure to the tube foot is high, the starfish-like tube foot has a large elongation, with a length of L1. The end furthest from the pneumatic interface is a flexible contact end, used to contact the external environment and transmit thrust or support force. That is, when air is injected into the starfish-like tube foot through the pneumatic interface, under the constraint of the braided mesh tube, the air pressure is mainly converted into axial elongation, and the starfish-like tube foot pneumatic telescopic structure elongates from L0 to L1; after depressurization, it contracts and returns to its original position under the elastic action of the braided mesh tube and soft material.

[0023] The soft robot support and walking mechanism employing the aforementioned feet includes multiple sets of foot units arranged in a horizontal and vertical array, fixed to the bottom of the robot body. Each set of foot units consists of multiple feet evenly distributed along the circumference. The feet are inclined to the bottom of the robot body. In this embodiment, each set of foot units consists of four feet. Figure 3 The starfish-like tubular foot array, arranged in different orientations, requires only a single pneumatic interface to complete the inflation and deflation / retraction of all the starfish-like tubular feet in the array, significantly simplifying the air path and overall structure. The pneumatic interface of the starfish-like tubular feet is connected to a centralized air source and an array of solenoid valves via air pipes, and is independently controlled by a control circuit. This allows for the individual or combined adjustment of the extension and retraction states of the starfish-like tubular feet according to a predetermined sequence, thereby driving the soft robot's movement in different orientations. Figure 4 This is a schematic diagram of a soft robot in a standing position, based on a starfish-like tube foot design.

[0024] By individually or in combination adjusting the extension and retraction states of each starfish-like tube foot according to a predetermined sequence, multi-directional propulsion and posture adjustment can be achieved. Coordinated movement of multiple starfish-like tube feet is achieved through gait planning, gait control, and parameter adjustment: a gait sequence is pre-set based on the number and arrangement of the starfish-like tube feet, determining the working order and timing of each foot; air pressure is applied or released to the pneumatic interface of the target starfish-like tube foot according to the gait sequence, switching it between supported and extended states; the alternating extension and retraction of the starfish-like tube feet enables the soft robot to move in different directions; by adjusting the air pressure and duration of each pneumatic interface, the extension and retraction amount and output force of each starfish-like tube foot are controlled to match different loads and ground conditions.

[0025] Example 1: like Figure 5 This embodiment describes the linear walking motion process of the soft robot. Four starfish-like tubular legs form a group, in... Figure 3 The four legs are labeled 1, 2, 3, and 4 respectively. All the starfish-like legs that make up the soft robot are arranged in a linear array with the four starfish-like legs in a group.

[0026] The linear walking motion process of a soft robot is as follows: Figure 5 As shown. For example, for Figure 3 The starfish-like legs, arranged in a linear array (number 4), are inflated, gradually transitioning the legs from a supported state to an extended state. Due to the angular offset between the arrangement of each leg and the horizontal plane, a significant thrust is generated between the leg array and the ground during extension, enabling small-range movement of the soft robot as a whole. During the transition from a supported state to maximum extension, the soft robot continuously... Figure 5 The arrow indicates movement in the direction of the object, with a maximum distance traveled being d. Then... Figure 3 The starfish-shaped tubing, arranged in a linear array with feet 1 and 3, is inflated. Once the starfish-shaped tubing, arranged in a linear array with feet 1 and 3, transitions from a supported state to its maximum elongation state, [the following is done / does not occur]. Figure 3 The No. 4 starfish-shaped tube feet, arranged in a linear array, are depressurized and retracted to a support state. Further adjustments are made to... Figure 3 The starfish-like legs (numbers 1 and 3) are depressurized and retracted to their supporting state in a linear array, causing the soft robot to return to its initial position. This gait design ensures that the soft robot does not jump during movement, guaranteeing smooth motion. By repeating the above steps, the soft robot can move in one direction through the alternating extension and retraction of the starfish-like leg array. Figure 5 (a) A diagram showing the motion of a soft robot in a standing position, viewed from the front. Figure 5 (b) Viewing the soft robot from a top-down perspective during one motion cycle ( Figure 5 The movement process of ①-⑥ in (a) is such that the straight-line distance traveled from the initial position 1 to the position 2 is d.

[0027] Example 2: like Figure 6 , Figure 7 and Figure 8 This embodiment provides the motion processes of the soft robot, including straight-line walking, direction changing, and movement through curved channels.

[0028] The linear walking motion process of a soft robot is as follows: Figure 6 As shown. For example, for Figure 3 The starfish-like legs, arranged in a linear array along with legs 1 and 4, are inflated, gradually transforming them from a supported state to their maximum elongation state. Under the influence of all the starfish-like legs arranged in a linear array along with legs 1 and 4, the soft robot as a whole will... Figure 6 Move in the direction of the arrow shown; then immediately move towards Figure 3Inflate all the starfish-like tubing feet, including No. 2 and No. 3, which are arranged in a linear array, to gradually transition them from a supported state to their maximum elongation state; then... Figure 3 The starfish-like tubular feet (numbers 1 and 4) are arranged in a linear array, and their air supply is cut off to gradually transition them to a supporting state. During this process, the soft robot continues to move a certain distance in the direction indicated by the arrow. The distance the soft robot moves in the direction indicated by the arrow after the above process is d'. Finally, the air supply is cut off to the starfish-like tubular feet (numbers 1 and 4), causing it to gradually transition to a supporting state. Figure 3 By cutting off the air supply to the starfish-like tubular feet (numbers 1 and 4) arranged in a linear array, the soft robot gradually returns to its initial support state, and the entire robot returns to its initial walking state. This walking mechanism ensures the smooth operation of the soft robot. Repeating the above steps, through the alternating extension and contraction of the starfish-like tubular foot array, allows the soft robot to move smoothly. Figure 6 The linear motion is indicated by the arrow shown. Figure 6 (a) Observe the motion of the soft robot from the direction perpendicular to its direction of motion, such as... Figure 6 As shown. Due to the asymmetry of the starfish-like tubular feet distributed across the length and width of the soft robot, some of the No. 1 and No. 4 starfish-like tubular feet will be obscured when viewed from this direction. To make the movement process of the soft robot more intuitive, some of the No. 1 and No. 4 starfish-like tubular feet have been omitted, leaving only those shown below. Figure 6 (a) shows parts 1 and 4 of the starfish-shaped tube feet. Figure 6 (b) Viewing the soft robot from a top-down perspective during one motion cycle ( Figure 6 The movement process of ①-⑥ in (a) is such that the distance d' is the distance the arrow points from the initial position 1' to the position 2'.

[0029] The soft robot of this invention can achieve walking motion in 8 directions, and the soft robot can change direction by combining the motion in multiple directions. Figure 7 This is a schematic diagram illustrating the reversing motion process of the soft robot of the present invention. The reversing motion process is divided into two stages: Stage 1 and Stage 2 (Stage 2'). The soft robot first moves from position ① to position ③ along the direction of the arrow shown in Stage 1. This stage involves... Figure 3 The system uses a linear array of starfish-like legs (number 4) to perform cyclic inflation and deflation steps, allowing the soft robot to undergo multiple cycles of inflation and deflation. Figure 5 (a) shows the motion cycle of ①-⑥; then the soft robot moves from position ③ to position ⑤ (⑤') along the arrow direction shown in stage two (stage two'). The mechanism of this process is the same as that in stage one, that is, for the above... Figure 3 The central actuator drives the soft robot to move in different directions, corresponding to the starfish-like tubular feet that perform cyclic inflation and deflation steps, allowing the soft robot to experience multiple similar processes. Figure 5 The motion cycles of ①-⑥ in (a).

[0030] Figure 8 This is a schematic diagram of the movement of the soft robot of the present invention through a curved channel. The turning motion process is divided into three stages: stage one, stage two, and stage three. The soft robot first moves from position ① to position ③ along the direction of the arrow shown in stage one. This stage involves... Figure 3 The system uses a linear array of starfish-like legs (number 4) to perform cyclic inflation and deflation steps, allowing the soft robot to undergo multiple cycles of inflation and deflation. Figure 5 (a) shows the motion cycle of ①-⑥; then the soft robot moves from position ③ to position ⑥ along the direction of the arrow shown in stage two. The mechanism of this process is similar to... Figure 6 The linear walking motion of the soft robot is the same; finally, the soft robot moves from position ⑥ to position ⑧ along the direction of the arrow shown in stage three. This stage is similar to the above. Figure 3 The system involves cyclically inflating and deflating the starfish-like legs (number 1 and number 1) arranged in a linear array. This allows the soft robot to undergo multiple similar inflation and deflation cycles. Figure 5 The motion cycles of ①-⑥ in (a).

[0031] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A sea star imitating tube foot, characterized in that: The starfish-like tube foot is composed of a columnar body and a woven mesh tube embedded in the columnar body; the material of the columnar body part is a soft material capable of elastic deformation under stress, one end of the columnar body part is a ground-touching end, the center of the columnar body part is provided with an axial ventilation blind hole, and the other end of the columnar body part is provided with a pneumatic interface for connecting with an external air source to realize the introduction of gas into the ventilation blind hole; the woven mesh tube is coaxially embedded in the outer periphery of the ventilation blind hole of the columnar body in a pre-compressed state along the axial direction, and the woven mesh tube is used to constrain the radial expansion deformation of the tube foot and guide the axial elongation when the gas is introduced into the ventilation blind hole, the starfish-like tube foot is driven to produce axial elongation movement by applying air pressure to the pneumatic interface, and the tube foot is automatically contracted and reset under the elastic action of the woven mesh tube and the columnar body after pressure relief.

2. The sea star imitating tube foot according to claim 1, characterized in that: The columnar body material is polydimethylsiloxane PDMS, polyurethane PU, hydrogel, natural rubber, vulcanized rubber or silicone-based rubber.

3. The sea star imitated tube foot according to claim 1, characterized in that: The manufacturing method of the starfish-like tube foot comprises the following steps: Step 1: cut a woven mesh tube with a suitable length, the length of the woven mesh tube is less than the designed length of the tube foot; then insert two rings into the inside of the two ends of the woven mesh tube and bond and fix them with the two ends of the woven mesh tube to form a woven mesh tube combination; Step 2: then axially pre-compress the woven mesh tube combination, position it in a tube foot forming mold after pre-compression, pour the forming material of the columnar body into the mold, and pour the woven mesh tube into the columnar body to form a starfish-like tube foot.

4. A soft robot support walking mechanism using the starfish-imitated tube foot according to any one of claims 1-3. The robot body is provided with a plurality of groups of tube foot units arranged in a transverse and longitudinal array, each group of tube foot units is composed of a plurality of tube feet uniformly distributed in the circumferential direction, and the tube feet are arranged obliquely with the bottom of the robot body.

5. The soft robotic support walking mechanism of claim 4, wherein: Each group of tube foot units is composed of four tube feet.

6. The soft robotic support walking mechanism of claim 4, wherein: According to a predetermined gait sequence, air pressure is applied to or released from the pneumatic interface of at least one starfish-like tube foot to drive the starfish-like tube foot to elongate or contract, thereby driving the robot body to move directionally relative to the ground.

7. The motion control method of claim 6, wherein: During gait control, the amount of expansion and contraction and the output force of the starfish-like tube foot are accurately controlled by controlling the size and duration of the air pressure applied to the pneumatic interface.

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