CN114631917A

CN114631917A - Pneumatic soft artificial limb hand

Info

Publication number: CN114631917A
Application number: CN202210301001.4A
Authority: CN
Inventors: 张震; 唐煜桂; 刘碧珊; 王昶茹
Original assignee: Shanghai Robot Industrial Technology Research Institute Co Ltd; University of Shanghai for Science and Technology
Current assignee: Shanghai Robot Industrial Technology Research Institute Co Ltd; University of Shanghai for Science and Technology
Priority date: 2022-03-24
Filing date: 2022-03-24
Publication date: 2022-06-17

Abstract

The invention discloses a pneumatic soft prosthetic hand which adopts the matching combination of double-joint soft fingers, single-joint soft fingers and a base, and double-joint soft fingers and single-joint soft fingers; the double-joint soft finger integrates a proximal interphalangeal joint and a distal interphalangeal joint in each finger into one soft joint, and takes a metacarpophalangeal joint as a second soft joint as an index finger, a middle finger and a ring finger of the prosthetic hand; the single-joint soft finger integrates all interphalangeal joints in each finger into a soft joint which is used as the thumb and the little finger of the artificial hand. The soft artificial hand related by the invention can realize the bending action similar to human fingers, has higher bending response speed and is easier to meet the real-time target in the field of human-computer interaction.

Description

Pneumatic soft artificial limb hand

Technical Field

The invention relates to a soft artificial hand, relating to the field of bionic machinery and the field of biomedicine.

Background

Currently, considering the inconvenience of people with limb disabilities in life, the research on artificial limbs for such people is receiving much attention. Most of the traditional artificial hands are rigid mechanical structures, and fingers are driven by a motor and a wire to bend. In recent years, based on the high adaptability of flexible materials, the soft bionic prosthetic hand enters the visual field of researchers and is used for ensuring the safety of daily grasping. The existing soft bionic finger mostly adopts a driving mode of expansion of a corrugated pipe, and an air cavity caused by inflation drives the whole finger to bend towards a certain direction. For example, the invention of chinese patent CN 111409089 a discloses a soft bionic finger and a bionic manipulator, wherein a wave-shaped telescopic structure is used to connect two sections of hollow soft knuckle, and the inner cavity of the telescopic structure is used to generate bending during inflation, thereby forming a bionic effect similar to a human hand.

However, the wavy telescopic structure in the design needs larger air pressure to drive, the bending angle is limited, the speed of driving deformation is slower, and the design scheme has poor effect in the field of artificial limbs focusing on human-computer interaction real-time performance.

Based on the above problems, how to improve the deformation response speed of the prosthetic hand on the premise of ensuring the bionic effect becomes a problem which needs to be solved urgently.

Disclosure of Invention

In order to solve the problems in the prior art, the invention aims to overcome the defects in the prior art, and provides a pneumatic soft prosthetic hand which has a rapid deformation characteristic.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

a pneumatic soft artificial hand adopts the matching combination of double-joint soft fingers, single-joint soft fingers and a base, and double-joint soft fingers and single-joint soft fingers;

the double-joint soft finger integrates a proximal interphalangeal joint and a distal interphalangeal joint in each finger into one soft joint, and takes a metacarpophalangeal joint as a second soft joint as an index finger, a middle finger and a ring finger of the prosthetic hand;

the single-joint soft finger integrates all interphalangeal joints in each finger into a soft joint which is used as the thumb and the little finger of the artificial hand.

Preferably, in the double-joint type soft finger, the number of air cavities contained in the two soft joints is different; wherein, the metacarpophalangeal joint has fewer soft joint air cavities corresponding to the proximal interphalangeal joint and more soft joint air cavities corresponding to the distal interphalangeal joint.

Preferably, the soft joints in the double-joint soft finger and the single-joint soft finger are formed by connecting a horizontal bottom layer and a zigzag hollow top layer, and the inside of the soft joints are communicated to form a zigzag air cavity.

Preferably, the zigzag air cavities are closely arranged, and the side walls of the adjacent air cavities can be extruded mutually after being expanded in an inflated state.

Preferably, the thickness of the bottom layer of the soft finger is not less than that of the hollow top layer, so that the bottom layer has higher rigidity.

Preferably, the zigzag hollow top layer and the horizontal bottom layer of the soft finger are made of silica gel materials with different hardness, the horizontal bottom layer is made of silica gel with higher hardness, and the top layer is made of silica gel with lower hardness.

Preferably, each air chamber in the soft body joint is of a structure with a cross section of which the side wall is thinner than the top wall, and the side wall of the air chamber is preferentially expanded when the air chamber is inflated.

Preferably, each zigzag air cavity side surface of the soft joint is a combination of a rectangle and an isosceles trapezoid.

Preferably, the fingertip part and the finger belly part of the soft finger are both designed into circular arcs.

Preferably, two joints of the double-joint soft finger are respectively controlled by different tracheal channels, so that independent joint bending can be realized.

Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:

1. the pneumatic soft prosthetic hand consists of double-joint soft fingers and single-joint soft fingers, and is bent like human fingers by expansion of air cavities in zigzag joints during inflation; meanwhile, mutual extrusion occurs between the side walls of the cross sections of the adjacent air cavities in the expansion process, so that the finger bending speed is remarkably increased, and quick response is realized; in addition, because the thickness of the bottom layer of the finger is larger, the center of mass of the end surface of the air cavity of the finger tip deviates downwards from the air pressure action center, so that an extra end moment is generated at the finger tip part to help the finger tip to realize a larger bending angle; the bottom layer of the soft finger is made of silica gel with higher hardness, so that the soft finger has a supporting effect similar to human finger bones, and the higher rigidity of the soft finger ensures that the soft finger can keep certain uprightness under the condition of no inflation;

2. in the aspect of control, each joint of the double-joint type soft finger can be independently controlled by an independent air passage, and the joint can be independently bent by connecting different air cavities through different air pipes; in the aspect of control, the air pressure driving scheme can realize stepless regulation of air pressure by means of a proportional valve so as to realize stepless regulation of the joint bending angle, and compared with a servo motor driving scheme of a rigid artificial hand, the pneumatic system has the advantages of simpler structure, higher response speed and better stepless regulation effect;

3. compared with the existing scheme, the soft artificial hand related by the invention can realize the bending action similar to human fingers, has higher bending response speed and is easier to meet the real-time target in the field of human-computer interaction.

Drawings

Fig. 1 is a schematic plan view of a double-joint soft finger according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of the double-joint soft finger shown in fig. 1.

Fig. 3 is a schematic structural view of the serrated top layer of the double-jointed soft finger designed by the present invention.

Fig. 4 is a schematic plan view of a single-jointed soft finger according to an embodiment of the present invention.

Fig. 5 is a schematic perspective view of an embodiment of the pneumatic soft prosthetic hand according to the present invention.

Fig. 6 is a schematic perspective view (another angle) of an embodiment of the pneumatic soft prosthetic hand according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following preferred embodiments, which are illustrated in the accompanying drawings. It should be noted that the specific embodiments described herein are only for explaining the present invention and do not limit the present invention. All embodiments that can be obtained by a person skilled in the art without making any inventive step based on the embodiments of the present invention belong to the protection scope of the present invention.

It should be noted that the technical solutions of each embodiment are allowed to be combined with each other, but must be a basis for a person skilled in the art to be able to realize, and when the technical solutions are combined and cannot be realized or contradicted with each other, such solutions should not be considered to exist, and are not within the protection scope of the present invention.

The above-described embodiments are further illustrated below with reference to specific examples, in which preferred embodiments of the invention are detailed below:

the first embodiment is as follows:

in this embodiment, a pneumatic soft prosthetic hand adopts the combination of double-joint soft fingers, single-joint soft fingers and a base, and double-joint soft fingers and single-joint soft fingers;

The pneumatic soft prosthetic hand of the embodiment can realize the bending action similar to human fingers, has higher bending response speed and is easier to meet the real-time target in the field of human-computer interaction.

Example two:

this embodiment is substantially the same as the first embodiment, and is characterized in that:

in this embodiment, in the double-joint soft finger, the two soft joints have different numbers of air cavities; wherein, the metacarpophalangeal joint has fewer soft joint air cavities, and the metacarpophalangeal joint has more soft joint air cavities corresponding to the proximal interphalangeal joint and the distal interphalangeal joint.

In this embodiment, the soft joints of the double-joint soft finger and the single-joint soft finger are formed by connecting a horizontal bottom layer and a zigzag hollow top layer, which are communicated to form a zigzag air cavity. The zigzag air cavities are tightly arranged, and the side walls of the adjacent air cavities can be extruded mutually after being expanded in an inflated state. The thickness of the bottom layer of the soft finger is not less than that of the hollow top layer, so that the bottom layer is guaranteed to have higher rigidity. The hollow top layer of cockscomb structure and the horizontal bottom layer of software finger are the silica gel material that hardness is different respectively, and horizontal bottom surface is made by the great silica gel of hardness, and the top layer is then made by the silica gel of hardness less. Each air cavity in the soft body joint is of a structure that the cross section side wall is thinner than the top wall, and the side wall of the air cavity can expand preferentially when the air cavity is inflated.

In this embodiment, each zigzag air cavity side of the soft joint is a combination of a rectangle and an isosceles trapezoid.

In this embodiment, the tip portion and the finger-belly portion of the soft finger are both designed to be circular arcs.

In this embodiment, the two joints of the double-joint soft finger are controlled by different tracheal channels.

The pneumatic soft prosthetic hand of this embodiment is a pneumatic soft prosthetic hand who possesses quick deformation characteristic, and the bending angle of increase finger realizes stronger gripping performance, because can take place mutual extrusion between the adjacent air cavity lateral wall when the air cavity inflation to make the crooked response of finger faster, change and satisfy the target to the real-time in the human-computer interaction field.

Example three:

this embodiment is substantially the same as the above embodiment, and is characterized in that:

in this embodiment, referring to the embodiment of the double-joint type soft finger shown in fig. 1 to 2, the finger includes a fingertip portion 3, a knuckle portion 6, a base portion 7, and a soft joint 1 and a soft joint 2 connected to the three portions. The air cavities of the soft joints 1 and the soft joints 2 are both of zigzag structures with cross section side walls 8 thinner than top walls 9, the side surfaces of the soft joints are in a combination of a rectangle and an isosceles trapezoid, and sectional zigzag hollow top layers of the soft joints are connected with a horizontal bottom layer 5 to form a closed air cavity. The soft body joint 1 and the soft body joint 2 have different numbers of zigzag air cavities, the soft body joint 1 corresponds to a metacarpophalangeal joint, the number of the air cavities is less, the soft body joint 2 simultaneously corresponds to a near side interphalangeal joint and a far side interphalangeal joint, and the number of the air cavities is more. The thickness of the bottom layer 5 of the double-joint type soft finger is larger than that of the top wall 9, and the hardness of the silica gel material used by the bottom layer 5 is larger than that of the sawtooth-shaped hollow top layer. The fingertip part 3 and the finger belly part 4 of the soft finger are both designed into circular arc shapes.

The whole double-joint soft finger designed in this embodiment is made of two types of silica gel with different hardness, wherein the top layer of the saw-tooth shape is made of low-hardness silica gel, and the bottom layer is made of silica gel with higher hardness. The finger tip part 3, the knuckle part 6 and the finger root part 7 are connected through the soft joint 1 and the soft joint 2, and the finger is driven to bend more quickly by utilizing the mutual extrusion phenomenon generated when the air cavities at the soft joint are inflated and the side walls 8 of the adjacent air cavities are inflated. The bending angles of the fingers caused by different numbers of the air cavities of the soft joints 1 and the soft joints 2 correspond to different bending angles which can be achieved by the joints of the human hand in the gripping process, for example, in the gripping action, the bending angle of the metacarpophalangeal joint is usually within 90 degrees, and the sum of the bending angles of the other two joints is far greater than 90 degrees, so that the bionic effect which is more similar to the fingers of the human body is realized. In addition, for the double-joint type soft finger designed by the invention, the

soft joints

1 and 2 are respectively controlled by the

independent air passages

12 and 13, different air pipes are respectively fixed on the

air passages

12 and 13 and are connected with the soft joint 1 and the soft joint 2, so that the bending of the joints of the finger part is realized, and the soft finger is endowed with richer deformation postures.

In this embodiment, the hollow top layer of cockscomb structure is connected with horizontal bottom, forms continuous cockscomb

structure air cavity

10 and 11 in the joint position, the cross section of cockscomb structure is rectangle and semicircular combination, and the side of every air cavity is isosceles trapezoid and rectangular combination, can effectively avoid aerifing the too big phenomenon of local stress that produces, improves the aesthetic measure of whole finger simultaneously. Because the silica gel hardness that the software finger bottom surface chose for use is great, the bottom layer that hardness is bigger can play the effect of "skeleton" to improve the rigidity of whole finger, guarantee that the finger also can keep certain upright nature under the condition of not aerifing, avoid taking place unnecessary deformation because silica gel is too soft. In addition, because the rigidity of the silica gel is in direct proportion to the thickness, in actual work, when the

closed air cavities

10 and 11 at the joint positions are inflated through the air

pressure input channels

12 and 13, the cross section side walls 8 thinner than the top wall 9 and the bottom surface 5 can be preferentially expanded, so that the structure of the serrated top layer is stretched, the elastic modulus of the horizontal bottom surface is far larger than that of the serrated structure, and the deformation is far smaller than that of the serrated structure, so that the whole finger can be bent by means of the deformation difference between the top layer and the bottom surface. Meanwhile, because each air cavity of the sawtooth-shaped structure is closely arranged, the expanded cross section side walls 8 can be mutually extruded, and the extrusion force between the side walls further accelerates the bending change of the fingers. In the aspect of finger bending angle, because the bottom layer 5 is thick, the mass center of the end surface of the finger air cavity deviates downwards compared with the air pressure action point, and the deviation of the mass center enables the end surface of the finger air cavity to be subjected to an end moment pointing to the direction of the bottom layer. Therefore, the tip portion 3 of the soft finger will be bent additionally under the action of the end moment. And finally, the side surface of each air cavity is designed to be a combination of a rectangle and an isosceles trapezoid, so that a certain space is reserved for the reverse bending of the soft finger. When applying vacuum negative pressure for soft body joint 1 and soft body joint 2, the air cavity shrink drives the reverse bending of soft body finger, and at this moment, the isosceles trapezoid air cavity structure at air cavity top can contract for approximate triangle-shaped structure under the negative pressure effect for the contact is inseparabler after the air cavity shrink of adjacent arranging, guarantees that the soft body finger can reverse bending to bigger angle, is favorable to snatching the bigger target of volume.

In the double-joint soft finger designed in this embodiment, the number of the air cavities of the soft joints 1 and the soft joints 2 is different, which respectively corresponds to the bending degree of different joints of the human finger in the gripping process. The metacarpophalangeal joints of the human hand correspond to the soft joints 1 with a small number of air cavities, and the proximal interphalangeal joints and the distal interphalangeal joints of the human hand are considered to have a cooperative relationship in most scenes, so that the proximal interphalangeal joints and the distal interphalangeal joints are integrated into one joint corresponding to the soft joints 2, and the control of the artificial hand is simplified. In the actual gripping work, the sum of the bending angles of the proximal interphalangeal joint and the distal interphalangeal joint is larger than the bending angle of the metacarpophalangeal joint, while the number of the air cavities of the soft joints 2 in the double-joint type soft finger designed by the invention is larger than that of the air cavities of the soft joints 1, and the bending angle of the soft joints 2 is larger than that of the soft joints 1 under the action of air pressure, so that the bending action similar to a human finger is realized, and the angle and the posture of the bent fingertip part 3 are similar to those of the bent fingertip of the human finger. Meanwhile, in order to improve the bionic performance, the finger is more similar to a human finger, and the finger tip part and the finger belly part of the finger are both designed into circular arcs, so that the gripped target object is protected, and the advantage of safer gripping of a soft hand is fully exerted.

In the present embodiment, a single-joint soft finger as shown in fig. 3 is also designed, the design principle is the same as that of a double-joint soft finger, and the only difference is that the single-joint soft finger only comprises a continuous sawtooth-shaped joint structure 14, and the reason for such design is that: the thumb and little finger of the human finger are obviously shorter than the rest three fingers, and in order to ensure the bionic property of the artificial hand, the thumb and little finger of the artificial hand are designed to be shorter in length; meanwhile, the number of the air chambers is positively correlated with the bending angle, and the continuously distributed saw teeth are beneficial to arranging more air chambers in a limited length, so that a larger bending angle is realized.

Based on the double-joint soft finger and the single-joint soft finger designed in this embodiment, this embodiment provides a soft prosthetic hand, which includes: a base 17, and the double-jointed soft finger 15 and the single-jointed soft finger 16 provided on the base. The base can be designed in a mode of imitating a palm of a human body according to actual needs; the double-joint soft fingers form the index finger, middle finger and ring finger of the soft artificial hand; the single-joint soft fingers form the thumb and the little finger of the soft artificial hand. The soft fingers are also arranged on the base 17 in a manner imitating the palm of a human body, as shown in fig. 5 and 6. The air pressure is input through the air pressure input port 18 on the base and distributed to the air pressure input channel of each soft finger, so that the bending control of different soft fingers is realized.

The soft artificial limb hand designed in this embodiment selects a scheme of mutually matching double-joint soft fingers and single-joint soft fingers. Considering that the length of the thumb and the little finger of the palm of the human body is short, and all joints on the thumb are required to rotate simultaneously when the grabbing action is completed, the invention selects the single-joint type soft finger as the thumb and the little finger of the soft artificial hand, and integrates all joints on the thumb and the little finger into one soft joint. On the premise of short length of the thumb and the little finger, the single-joint soft finger can arrange a large number of zigzag air cavities in short length, so that the bending angle of the little finger and the thumb of the soft prosthetic hand is not affected. Therefore, the designed soft artificial hand not only better conforms to the actual palm of a human body in the aspects of size and appearance, but also ensures that each finger can realize the bending angle similar to that of the finger of the human body.

In addition, in the aspect of control, the pneumatic soft prosthetic hand designed in the embodiment can steplessly adjust the bending angle of each joint according to the air pressure under the control of the proportional valve, so as to control the soft prosthetic hand to realize different action combinations.

In summary, the pneumatic soft prosthetic hand of the above embodiment comprises a double-joint soft bionic finger, a single-joint soft bionic finger and a base; the soft finger is in a hollow design with different thicknesses of an upper layer and a lower layer, and the top layer and the bottom layer of the soft finger are respectively composed of two types of silica gel with different hardness; the joint of the soft finger is in a hollow sawtooth pipe structure with a thinner side wall; the joint comprises a horizontal bottom layer and a segmented zigzag hollow top layer, wherein the bottom layer is made of silica gel with high hardness, the top layer is made of silica gel with low hardness, and the bottom layer and the top layer form a zigzag air cavity in a surrounding mode; two joints of the double-joint type soft finger are respectively controlled by different trachea channels, so that independent bending of the joints is realized. The index finger, the middle finger and the ring finger of the soft artificial hand are composed of double-joint bionic fingers, and the thumb and the little finger are composed of single-joint fingers with the same joint structure. According to the embodiment of the invention, the knuckle is communicated through the zigzag hollow joint, the fingers are driven to bend like a human hand by utilizing the preferential expansion of the side wall of the zigzag air cavity at the joint during inflation, and meanwhile, the center of mass shift phenomenon caused by the difference of the thicknesses of the upper layer and the lower layer enables the air pressure to form end moment at the end part of the fingers, so that the bending angle of the fingers is further increased, and the stronger gripping performance is realized. In addition, the finger can bend and respond more quickly because the adjacent air cavity side walls can be squeezed mutually when the air cavities expand.

The embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the embodiments, and various changes and modifications can be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be equivalent substitutions, as long as the purpose of the present invention is met, and the present invention shall fall within the protection scope of the present invention without departing from the technical principle and inventive concept of the present invention.

Claims

1. A pneumatic soft prosthetic hand is characterized in that: adopting the matching combination of double-joint soft fingers, single-joint soft fingers and a base, and double-joint soft fingers and single-joint soft fingers;

the double-joint type soft finger integrates a proximal interphalangeal joint and a distal interphalangeal joint in each finger into one soft joint, and takes a metacarpophalangeal joint as a second soft joint as an index finger, a middle finger and a ring finger of the prosthetic hand;

2. The pneumatic soft prosthetic hand of claim 1, wherein: in the double-joint type soft finger, the two soft joints have different air cavities; wherein, the metacarpophalangeal joint has fewer soft joint air cavities, and the metacarpophalangeal joint has more soft joint air cavities corresponding to the proximal interphalangeal joint and the distal interphalangeal joint.

3. The pneumatic soft prosthetic hand of claim 1, wherein: the soft joints in the double-joint soft fingers and the single-joint soft fingers are formed by connecting a horizontal bottom layer and a sawtooth-shaped hollow top layer, and the inside of the soft joints are communicated to form a sawtooth-shaped air cavity.

4. The pneumatic soft prosthetic hand of claim 3, wherein: the zigzag air cavities are tightly arranged, and the side walls of the adjacent air cavities can be extruded mutually after being expanded in an inflated state.

5. The pneumatic soft prosthetic hand of claim 3, wherein: the thickness of the bottom layer of the soft finger is not less than that of the hollow top layer, so that the bottom layer is guaranteed to have higher rigidity.

6. The pneumatic soft prosthetic hand of claim 3, wherein: the hollow top layer of cockscomb structure and the horizontal bottom layer of software finger are the silica gel material that hardness is different respectively, and horizontal bottom surface is made by the great silica gel of hardness, and the top layer is then made by the silica gel of hardness less.

7. The pneumatic soft prosthetic hand of claim 3, wherein: each air cavity in the soft joint is of a structure with a cross section side wall thinner than a top wall, and the side wall of each air cavity can be expanded preferentially when the air cavity is inflated.

8. The pneumatic soft prosthetic hand of any one of claims 3 to 7, wherein: the side surface of each zigzag air cavity of the soft joint is a combination of a rectangle and an isosceles trapezoid.

9. The pneumatic soft prosthetic hand of claim 3, wherein: the finger tip part and the finger belly part of the soft finger are both designed into circular arc shapes.

10. The bi-articular soft hand of claim 2, wherein: the two joints of the double-joint soft finger are respectively controlled by different trachea channels.