Pneumatic soft dexterous hand and soft robot suitable for patients with finger loss function

Abstract

The application belongs to the technical field of soft robots, and discloses a pneumatic soft dexterous hand suitable for patients with finger function loss and a soft robot, the pneumatic soft dexterous hand comprising a soft finger, the soft finger comprising a rubber shell, a silica gel tube, an endoskeleton and an embedded air bag, the silica gel tube being sleeved in the rubber shell; the silica gel tube is formed with a cavity, and the endoskeleton and the embedded air bag are arranged in the silica gel tube; the endoskeleton comprises a plurality of skeleton modules hinged together, the plurality of skeleton modules are divided into two groups, the two groups of skeleton modules are alternately arranged left and right and sequentially hinged; the embedded air bag is embedded on the endoskeleton and plays a supporting role on the endoskeleton. The application ensures that the soft finger itself will not be laterally bent due to external force based on the anisotropy of the endoskeleton.

Description

Technical Field

[0001] This invention belongs to the field of soft robot technology, and more specifically, relates to a pneumatic soft dexterous hand and soft robot suitable for patients with missing fingers. Background Technology

[0002] Dexterous hands are one of the main characteristics that distinguish humans from other animals. Human hands play a vital role in life, possessing exceptional dexterity to perform grasping objects and other complex tasks. However, a large number of people worldwide suffer from hand amputations or congenital hand deformities, and the loss of their hands causes them significant inconvenience. In addition to flexion and extension movements, the lateral swing of the fingers further enhances their grasping ability. Soft actuators, due to their excellent human-computer interaction, are increasingly being used as the basic motion unit in prosthetic hand design. Therefore, designing a pneumatic soft dexterous hand with flexion, extension, and lateral swing movements to reconstruct the functions of a missing hand has extremely important scientific research significance and social value.

[0003] Current humanoid soft actuators propose various joint-type bending actuators, but the permissible bending angles of each joint after passive compression, in addition to the active joint bending characteristic of the finger, have not been widely discussed. Furthermore, Chinese invention patent CN110497396A discloses a variable stiffness pneumatic soft actuator that uses several cascaded endoskeletons to enhance finger stiffness. However, because the endoskeletons are connected by ball joints, the soft finger, upon lateral impact, cannot exhibit lateral flexion movement only at the metacarpophalangeal joints like a human finger; instead, it is forced into uniform lateral flexion due to the overall compliance of the actuator. To solve this problem, it is necessary not only to provide the lateral flexion freedom of the metacarpophalangeal joints but also to ensure high stiffness in the lateral flexion direction of the finger itself. Chinese invention patent CN114347078A utilizes a worm gear to achieve lateral flexion movement of the finger, but its transmission mechanism occupies a large volume, making it unsuitable for disabled patients with only missing fingers.

[0004] Posture feedback is an indispensable step in closed-loop control during prosthetic hand use. Bragg gratings, with their excellent precision and high integration, can be used as detection units for soft actuators. Chinese invention patent CN113940712A utilizes a single optical fiber integrating multiple Bragg gratings to achieve precise control of the five fingers of a surgical robot. However, due to the inherent brittleness of optical fibers, excessively small bending radii render the fiber optic sensor unusable. When this sensor is used in the prosthetic hand field, the near-infinite bending radii between the fingers at the metacarpophalangeal joints prevent the optical fiber from directly adhering to the outer wall of the finger. Furthermore, since soft actuators may experience spatial bending, but the fiber optic feedback of bending is non-directional, determining the direction of fiber bending is also a challenging problem. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a pneumatic soft dexterous hand and soft robot suitable for patients with missing fingers. It addresses the shortcomings of current soft prosthetic hands, such as incomplete hand function and deficiencies in fiber optic sensor placement and detection. During flexion and extension movements, the pneumatic soft dexterous hand maintains the same bending ratio for both active and passive movements as the human hand. During lateral movement, the finger opening and closing angles change linearly with air pressure while ensuring a compact actuator size. Furthermore, this invention utilizes a single degree of freedom within the endoskeleton to prevent lateral bending of the soft fingers due to external forces.

[0006] To achieve the above objectives, according to one aspect of the present invention, a pneumatic soft dexterous hand suitable for patients with missing finger function is provided. The pneumatic soft dexterous hand includes a soft finger, which includes a rubber shell, a silicone tube, an endoskeleton, and an internal air bladder. The silicone tube is sleeved inside the rubber shell. The silicone tube has a cavity, and the endoskeleton and the internal air bladder are disposed inside the silicone tube.

[0007] The endoskeleton includes multiple skeleton modules that are hinged together. The multiple skeleton modules are divided into two groups, and the two groups of skeleton modules alternate left and right and are hinged to each other in sequence. The built-in airbag is embedded in the endoskeleton and provides support for the endoskeleton.

[0008] Furthermore, the skeleton module includes a connecting plate, a limiting shaft, and a rotating shaft. One end of the limiting shaft and the rotating shaft are respectively fixedly connected to the connecting plate, and the connecting plate is also provided with a rotating hole. The other end of the rotating shaft is hinged to the rotating hole of another skeleton module. Thus, multiple skeleton modules are hinged together to form the endoskeleton.

[0009] Furthermore, the connecting plate is provided with an optical fiber hole in the area adjacent to the rotating hole, which is used for the optical fiber to pass through; multiple Bragg gratings are integrated on the optical fiber, and the pneumatic soft dexterous hand realizes the detection of the degrees of freedom of each joint through the optical fiber; the optical fiber extends into the silicone tube from the air port at the end of the silicone tube, passes through multiple optical fiber holes in sequence, and then extends out from another air port at the end of the silicone tube and into the adjacent soft finger; the optical fiber is arranged along the bone module inside the silicone tube.

[0010] Furthermore, the pneumatic soft dexterous hand also includes a finger base, a receiving cavity, and a spring airbag. The finger base connects the soft finger and the receiving cavity. One side of the receiving cavity is movably connected to the finger base, and the other end is used to connect to the human stump. The two opposite ends of the spring airbag are respectively connected to two adjacent finger bases.

[0011] Furthermore, one side of the receiving cavity is designed to fit against the human limb remnant, while the other side has an arc-shaped dovetail groove. The arc-shaped dovetail groove cooperates with the finger base to form a movable connection, ensuring that the finger can deflect along the arc-shaped dovetail groove.

[0012] Furthermore, the hardness of the rubber shell is greater than that of the silicone tube, one end of which is open for the silicone tube to pass through, and the other end is pointed and closed; the rubber shell has hollowed-out notches in the areas corresponding to the metacarpophalangeal joint, proximal interphalangeal joint and distal interphalangeal joint respectively.

[0013] Furthermore, the notches corresponding to the metacarpophalangeal joints, proximal interphalangeal joints, and distal interphalangeal joints have differentiated bottom lines on the palm side, and the length of the bottom line of the notch determines the proportional coefficient of the corresponding joint bending.

[0014] Furthermore, the rubber shell has notched protrusions on the notched sidewalls corresponding to the distal and proximal interphalangeal joints, along the axial direction of the rubber shell.

[0015] Furthermore, the spring airbag includes a first connecting block, a second connecting block, a variable diameter spring, and a non-stretchable plastic film. The two ends of the variable diameter spring are respectively connected to the first connecting block and the second connecting block. The plastic film is cylindrical, and its two ends are respectively connected to the first connecting block and the second connecting block. The variable diameter spring is located inside the plastic film, and its cross-sectional diameter gradually decreases from the middle to both ends along its own axis.

[0016] According to another aspect of the invention, a robot is provided, wherein the soft hand of the soft robot is a pneumatic soft dexterous hand as described above, suitable for patients with missing finger function.

[0017] In summary, compared with the prior art, the pneumatic soft dexterous hand and soft robot for patients with missing fingers provided by the present invention have the following beneficial effects:

[0018] 1. This invention, through the internal hinge connecting the endoskeleton and the built-in airbag, restricts the lateral swing direction and bending and twisting of the soft fingers during the grasping process of the dexterous hand, ensuring that the dexterous hand has the flexibility of a soft actuator, while improving the motion accuracy.

[0019] 2. This invention uses an airbag with an embedded variable diameter spring as the actuator for the lateral swing motion of the dexterous hand, ensuring the motion function while making the actuator small and lightweight, and allowing control over the opening and closing angle of the dexterous hand.

[0020] 3. The use of a hollowed-out rubber shell to achieve joint-like bending ensures that, during the flexion and extension movements of the soft fingers, whether actively bent or passively deformed by pressure, the achievable bending angle and bending ratio of the dexterous hand fingers are consistent with those of the human hand.

[0021] 4. The dexterity hand posture is measured using an optical fiber integrated with multiple Bragg gratings. The single degree of freedom of the endoskeleton and finger base ensures the clarity of the grating bending direction and avoids the problem of optical fiber sensor failure due to the small curvature radius of the finger gap. Attached Figure Description

[0022] Figure 1 This is an installation diagram of a pneumatic soft dexterous hand suitable for patients with missing finger function, provided by the present invention;

[0023] Figure 2 yes Figure 1 A partial exploded diagram of a pneumatic soft dexterity hand suitable for patients with missing fingers;

[0024] Figure 3 (a) and (b) in the text are respectively Figure 1 A schematic diagram and cross-sectional view of a soft finger for a pneumatic soft dexterity hand suitable for patients with missing finger functions;

[0025] Figure 4 yes Figure 3 A schematic diagram of the degrees of freedom of motion of the rubber shell of the soft finger in the diagram;

[0026] Figure 5 yes Figure 3 A schematic diagram of the installation of the endoskeleton, built-in airbag, and optical fiber of the soft finger in the image.

[0027] Figure 6 yes Figure 5 A schematic diagram of the skeletal modules of the endoskeleton;

[0028] Figure 7 yes Figure 1 A schematic diagram of a spring-loaded airbag for a pneumatic soft dexterity hand suitable for patients with missing fingers;

[0029] Figure 8 This is a schematic diagram from another angle of a pneumatic soft dexterous hand provided by the present invention, suitable for patients with missing finger function.

[0030] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-soft finger, 2-finger base, 3-spring airbag, 4-receiving cavity, 5-silicone tube, 6-rubber shell, 7-cavity, 8-endoskeletal system, 9-built-in airbag, 10-optical fiber, 11-bottom edge of notch, 12-notch protrusion, 13-rotation axis, 14-rotation hole, 15-limiting axis, 16-optical fiber hole, 17-plastic film, 18-variable diameter spring, 19-Bragg grating. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Please see Figure 1 and Figure 2 This invention provides a pneumatic soft dexterous hand suitable for patients with missing fingers. The pneumatic soft dexterous hand includes a soft finger 1, a finger base 2, a receiving cavity 4, and a spring-loaded airbag 3. The finger base 2 connects the soft finger 1 and the receiving cavity 4. One side of the receiving cavity 4 is movably connected to the finger base 2, and the other end is used to connect to the residual limb. Adjacent finger bases 2 are connected by the spring-loaded airbag 3, with opposite ends of the spring-loaded airbag 3 connected to two adjacent finger bases 2. In this embodiment, the number of soft fingers 1, the number of finger bases 2, and the number of receiving cavities 4 are the same; a single soft finger 1 is the basic unit, and patients with missing fingers can flexibly choose the number of fingers to wear according to their own circumstances.

[0033] Please see Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The soft finger 1 includes a rubber shell 6, a silicone tube 5, an endoskeleton 8, and an internal air bladder 9. One end of the rubber shell is open for the silicone tube 5 to pass through, while the other end is pointed and closed. The rubber shell 6 has perforated notches corresponding to the metacarpophalangeal joints, proximal interphalangeal joints, and distal interphalangeal joints. Due to the lower rigidity at these notches, pressure applied to the silicone tube 5 causes the soft finger 1 to bend at the notches. The length of the notch baseline near the palm side determines the bending ratio of each joint. The notch baseline lengths corresponding to the three joints are differentiated, achieving approximately proportional bending of the finger joints.

[0034] The hardness of the rubber outer shell 6 is greater than that of the silicone tube 5. The silicone tube 5 is fitted inside the rubber outer shell 6, and when it is compressed and stretched, it will compress the tip of the rubber outer shell 6, generating a torque towards the palm side, causing the soft finger 1 to bend inward. The stiffness at the bottom edge 11 of the notch is small, so the rubber outer shell 6 only bends and deforms at the bottom edge 11 of the notch when compressed. At the same time, since the amount of bending per unit length of the bottom edge 11 of the notch is consistent under the same bending moment, adjusting the length of the bottom edge 11 of the notch can achieve an approximately 3:2 bending ratio between the finger joints, realizing the reconstruction of the human hand's motor function during active movement.

[0035] One end of the rubber shell is open for the silicone tube 5 to pass through, while the other end is pointed and closed. Due to the low stiffness at the notch, the silicone tube 5, when pressurized, causes the soft finger 1 to bend inward at the bottom edge 11 of the notch. The length of the bottom edge 11 of the notch determines the proportional coefficient of the bending angle of each joint. The three joints adopt a differentiated design corresponding to the bottom edge 11 of the notch, so that the individual finger joints bend approximately in a certain proportion.

[0036] The rubber shell 6 has notched protrusions 12 on the sidewalls corresponding to the distal and proximal interphalangeal joints, along the axial direction of the rubber shell 6. When the soft finger 1 is subjected to external pressure and deforms towards the back of the hand, the notched protrusions 12 bend and contact, restricting the movement of the finger at each joint in the passive motion, thus limiting the range of bending of each joint in the back of the hand direction. Figure 4 The range of motion of the fingertip joints and metacarpophalangeal joints shown is approximately 0°, ensuring that the soft finger 1 can also achieve the movement law of the human hand during passive movement under pressure.

[0037] Glass fiber is wound around the outer periphery of the silicone tube 5, forming a cavity 7 inside. The endoskeleton 8 and the built-in airbag 9 are disposed within the cavity 7. The glass fiber is used to restrict the radial expansion of the silicone tube 5, so that the silicone tube 5 only undergoes axial stretching during pressurization.

[0038] The endoskeleton 8 comprises multiple hinged bone modules, which are divided into two groups. The two groups of bone modules alternate left and right and are hinged sequentially, ensuring the freedom of finger flexion and extension while restricting lateral bending or twisting. The built-in airbag 9 is embedded in the endoskeleton 8, providing support and ensuring that the endoskeleton 8 can be inserted into the soft finger 1 in one go, simplifying the manufacturing process.

[0039] The skeletal module includes a connecting plate, a limiting shaft 15, and a rotating shaft 13. One end of the limiting shaft 15 and the rotating shaft 13 are fixedly connected to the connecting plate. The connecting plate also has a rotating hole 14. The central axis of the rotating hole 14, the central axis of the limiting shaft 15, and the central axis of the rotating shaft 13 all pass through the same vertex of a triangle. The other end of the rotating shaft 13 is hinged to the rotating hole 14 of another opposite skeletal module. Multiple skeletal modules are hinged together to form the endoskeleton 8. An optical fiber hole 16 is also provided in the area of ​​the connecting plate adjacent to the rotating hole 14, for the passage of an optical fiber 10. In this embodiment, the central axis of the optical fiber hole 16 is perpendicular to the central axis of the rotating hole 14.

[0040] The limiting axes 15 of the two opposing skeletal modules are staggered, and the built-in airbag 9 is located between the limiting axis 15 and the rotation axis 13. Due to the restriction of the rotation axis 13 and the rotation hole 14, the endoskeleton 8 can only move in a plane perpendicular to the axis of the rotation axis 13. Considering the large number of parts in the endoskeleton 8 and its inability to maintain a stable state on its own, the non-stretchable built-in airbag 9, made of plastic, will ensure the vertical state of the endoskeleton 8 after being pressurized. Therefore, relying on the support of the built-in airbag 9 for the endoskeleton 8, the endoskeleton 8 can be inserted into the cavity 7 of the silicone tube 5 and fixed in position at once during the manufacturing process. The limiting axis 15 works together with the rotation axis 13 to restrict the built-in airbag 9 inside the endoskeleton 8. The combined use of the silicone tube 5 and the endoskeleton 8 achieves the dexterity of the fingers while ensuring that the soft fingers 1 have the bending resistance of human hand joints in the lateral direction.

[0041] The finger bases 2 are connected by spring airbags 3 to enable the lateral movement of the dexterous hand. One side of the receiving cavity 4 is designed to fit against the human stump, while the other side has an arc-shaped dovetail groove. This arc-shaped dovetail groove cooperates with the finger bases 2 to ensure that the finger can deflect along the groove.

[0042] The spring airbag 3 includes a first connecting block, a second connecting block, a variable-diameter spring 18, and a non-stretchable plastic film 17. The two ends of the variable-diameter spring 18 are connected to the first connecting block and the second connecting block, respectively. The plastic film 17 is cylindrical, with its two ends connected to the first connecting block and the second connecting block, respectively. The variable-diameter spring 18 is located within the plastic film 17. Initially, the spring airbag 3 is under negative pressure, compressing the variable-diameter spring 18 and allowing the dexterous hand's fingers to close and adhere. During operation, the spring airbag 3 is under positive pressure, causing the variable-diameter spring 18 to return to its original position, allowing the dexterous hand's fingers to swing laterally. The elongation of the airbag embedded with the spring changes linearly with pressure changes, thus adjusting the lateral swing amplitude of the fingers. Because the cross-sectional diameter of the variable-diameter spring 18 gradually decreases from the middle to both ends along its own axis, when the variable-diameter spring 18 is compressed, each layer of the spring can overlap, limiting the spring length to a thin plane.

[0043] Please see Figure 8 The dexterous hand uses a single optical fiber integrated with multiple Bragg gratings 19 to collect the degrees of freedom of each joint. Since the non-stretchable nature of the optical fiber 10 conflicts with the compressible and deformable nature of the soft finger 1, directly embedding the optical fiber 10 into the silicone tube 5 would cause it to break during deformation. Furthermore, considering that the feedback data from the Bragg grating 19 cannot determine directionality when reporting bending, the optical fiber 10 is embedded in the optical fiber holes 16 of each component unit within the endoskeleton 8. The optical fiber 10 extends into the silicone tube 5 from an air vent at one end. Each component unit of the endoskeleton 8 has an optical fiber hole 16 for inserting the fiber. The fiber is arranged roughly in a U-shape along the endoskeleton 8 within the silicone tube 5, and then exits from another air vent at the end of the silicone tube 5, extending from the finger base 2 into the adjacent soft finger 1. The Bragg gratings 19 are positioned at the corresponding joints of the dexterous hand, thus splitting the nearly 180° bending amount into two bending angles to ensure normal operation.

[0044] The present invention also provides a soft robot, wherein the soft hand of the soft robot is a pneumatic soft dexterous hand as described above, suitable for patients with missing fingers.

[0045] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A pneumatic soft dexterous hand suitable for patients with missing finger function, characterized in that: The pneumatic soft dexterous hand includes a soft finger, which includes a rubber shell, a silicone tube, an endoskeleton, and a built-in air bladder. The silicone tube is fitted inside the rubber shell. The silicone tube has a cavity, and the endoskeleton and the built-in air bladder are disposed inside the silicone tube. The endoskeleton includes multiple skeleton modules hinged together, which are divided into two groups. The two groups of skeleton modules alternate left and right and are hinged together in sequence. The built-in airbag is embedded in the endoskeleton and provides support for the endoskeleton. The pneumatic soft dexterous hand also includes a finger base, a receiving cavity, and a spring airbag. The finger base connects the soft finger and the receiving cavity. One side of the receiving cavity is movably connected to the finger base, and the other end is used to connect to the human stump. The two opposite ends of the spring airbag are respectively connected to two adjacent finger bases.

2. The pneumatic soft dexterous hand suitable for patients with missing finger function as described in claim 1, characterized in that: The skeleton module includes a connecting plate, a limiting shaft, and a rotating shaft. One end of the limiting shaft and the rotating shaft are respectively fixedly connected to the connecting plate, and the connecting plate is also provided with a rotating hole. The other end of the rotating shaft is hinged to the rotating hole of another skeleton module. Multiple skeleton modules are hinged together to form the endoskeleton.

3. The pneumatic soft dexterous hand suitable for patients with missing finger function as described in claim 2, characterized in that: The connecting plate also has an optical fiber hole in the area adjacent to the rotating hole, which is used for the optical fiber to pass through; multiple Bragg gratings are integrated on the optical fiber, and the pneumatic soft dexterous hand realizes the detection of the degree of freedom of each joint through the optical fiber; the optical fiber extends into the silicone tube from the air port at the end of the silicone tube, passes through multiple optical fiber holes in sequence, and then extends out from another air port at the end of the silicone tube and into the adjacent soft finger; the optical fiber is arranged along the bone module inside the silicone tube.

4. The pneumatic soft dexterous hand for patients with missing fingers as described in claim 1, characterized in that: One side of the receiving cavity is designed to fit against the human limb remnant, while the other side has an arc-shaped dovetail groove. The arc-shaped dovetail groove cooperates with the finger base to form a movable connection, ensuring that the finger can deflect and move along the arc-shaped dovetail groove.

5. The pneumatic soft dexterous hand suitable for patients with missing finger function as described in claim 1, characterized in that: The hardness of the rubber shell is greater than that of the silicone tube. One end of the rubber shell is open for the silicone tube to pass through, and the other end is pointed and closed. The rubber shell has hollowed-out notches in the areas corresponding to the metacarpophalangeal joint, proximal interphalangeal joint and distal interphalangeal joint.

6. The pneumatic soft dexterous hand for patients with missing fingers as described in claim 5, characterized in that: The notches corresponding to the metacarpophalangeal joints, proximal interphalangeal joints, and distal interphalangeal joints have different bottom lines on the palm side, and the length of the bottom line of the notch determines the proportional coefficient of the corresponding joint bending.

7. The pneumatic soft dexterous hand for patients with missing fingers as described in claim 5, characterized in that: The rubber shell has notched protrusions on the notched sidewalls corresponding to the distal and proximal interphalangeal joints, along the axial direction of the rubber shell.

8. The pneumatic soft dexterous hand for patients with missing fingers as described in claim 1, characterized in that: The spring airbag includes a first connecting block, a second connecting block, a variable diameter spring, and a non-stretchable plastic film. The two ends of the variable diameter spring are respectively connected to the first connecting block and the second connecting block. The plastic film is cylindrical, and its two ends are respectively connected to the first connecting block and the second connecting block. The variable diameter spring is located inside the plastic film, and its cross-sectional diameter gradually decreases from the middle to both ends along its own axis.

9. A soft robot, characterized in that: The soft hand of the soft robot is the pneumatic soft dexterous hand as described in any one of claims 1-8, suitable for patients with missing fingers.

Images