CN105619379B - A kind of software imitation human finger and preparation method thereof - Google Patents

Abstract

The invention discloses a soft humanoid finger and a preparation method thereof. One end of the soft humanoid finger is the end of the finger (5A), and the other end is the base of the finger (5B); the airflow duct (2) is installed on the base of the finger On (5B): the bottom panel of the hollow base body (3) is bonded with a strain limiting layer (30) and wound clockwise to form a fiber enveloping layer (4), and then the outer skin layer (1) is injection molded. The middle part of the hollow matrix (3) is an air bag (3A), and the soft humanoid finger can be deformed by filling the air bag (3A) with a certain pressure of gas or liquid. The Young's model of soft humanoid finger material designed by the present invention is 250kPa, which is close to the hardness of human skin. The maximum bending displacement of a single soft humanoid finger can reach 100mm, and the output force can reach 4N.

Description

A soft humanoid finger and its preparation method

technical field

The invention relates to a humanoid finger structure, more particularly, a software humanoid finger with structure pre-programmed.

Background technique

As an effective extension of human limbs, humanoid finger is one of the important topics in the field of robotics research. Compared with the simple and common end effector, the humanoid finger is highly similar to the shape and size of a real finger, and can complete flexible and precise movements. After decades of development, the humanoid finger has become a multidisciplinary system integrating electromechanical, sensing, materials, intelligence and driving. At present, traditional humanoid fingers generally achieve dexterous movements similar to human hands through complex multi-joint structures and exquisite drive systems. However, the design of this bionic finger is difficult, the development cycle is long, and the manufacturing cost is expensive. It requires complex sensor control and sophisticated components to ensure the reliability and safety of the action. At the same time, traditional humanoid fingers are mostly composed of rigid kinematic joints based on hard materials (metal, plastic, etc.), and the difference in texture from real human hands limits their interactive experience with the external environment.

In nature, many organisms, such as octopus tentacles and worms, can complete complex and efficient actions with simple flexible soft body structures. The structure of organisms has co-evolved with the central nervous system, forming a complete integrated neural-mechanical control system. Among them, the soft tissue structure is very important for organisms, which is conducive to adapting to the continuously complex environment: in the process of interaction between organisms and the environment, the contact area between the soft tissue structure and the environmental objects is large, so that it fits more closely with the environment. At the same time, the large-scale deformation and energy absorption characteristics of soft tissue reduce the effect of external force. The reaction force of the environment object on the living body can be widely distributed on the surface of the soft tissue structure, which can reduce the force impact and improve the safety.

Contents of the invention

The invention designs a soft humanoid finger, which is essentially different from the traditional rigid humanoid finger. The soft humanoid fingers are all made of flexible materials to make a layer structure (the layer structure is a hollow matrix layer, a fiber envelope layer and an outer skin layer from the inside to the outside, and the bottom panel of the soft humanoid finger is from the inside to the outside. Hollow matrix layer, strain-limiting bottom layer, fibrous envelope layer and outer skin layer) instead of traditional rigid plastic or metal. The closed cavity (i.e. airbag 3A) at the center of the hollow matrix (3) applied to the soft humanoid finger of the present invention can realize different curvatures by setting the layout and material of the fiber envelope (4) and the strain-limited bottom layer (30) And the bending action of the curve, that is, the under-actuated flexible motion is realized in a structural "pre-programmed" way, thereby reducing the structural complexity of the soft humanoid finger. At the same time, the soft humanoid finger adopts a passive control strategy, which has significant advantages in terms of cost, volume, and system complexity compared with traditional bionic fingers that adopt active control methods. Since the flexible material matrix has little resistance to pressure, the soft humanoid finger can absorb external impact and better adapt to the shape and size of the interactive object. At the same time, the application of flexible soft materials can make the humanoid fingers closer to the shape and texture of real fingers. The rapid and low-cost manufacturing of soft humanoid fingers also makes them suitable for operations in high-risk industries and for the customization of future bionic robots. At the same time, the highly anthropomorphic characteristics and inherent safety of the soft bionic finger can greatly improve its ability to interact with external environmental objects (such as people, animals, fragile objects, etc.).

In the present invention, when gas or liquid is pressed in, the closed cavity (i.e., the airbag 3A) at the center of the hollow base (3) expands as much as possible along the axial direction and the radial direction like a balloon. When the fiber envelope layer (4) with a small expansion coefficient is added to the closed cavity in the axial direction, the radial deformation of the closed cavity is limited, and it can only expand along the axial direction, no longer a purposeless extension, Rather, it is equivalent to the telescopic movement of the closed cavity. When a layer of strain-limiting bottom layer (30) with a small expansion coefficient is added on one side of the closed cavity, the expansion deformation in the axial direction of the corresponding side of the closed cavity is restricted. In this way, when the internal pressure of the closed cavity increases, there is a difference in the degree of expansion and deformation on both sides of the axis, which will cause the soft bionic finger to produce a bending movement as a whole.

A soft humanoid finger of the present invention is characterized in that: said soft humanoid finger comprises a hollow base (3), a strain limiting layer (30), a fiber envelope (4), an outer skin layer (1) and Air duct (2). One end of the soft humanoid finger is a finger end (5A), and the other end is a finger root (5B). The airflow conduit (2) is installed on the root of the finger (5B). The bottom panel of the hollow base body (3) is bonded with a strain limiting layer (30) and wound clockwise to form a fiber enveloping layer (4). Between the matrix (3) and the outer skin layer (1) is a fibrous enveloping layer (4). The fiber envelope layer (4) is composed of clockwise winding (4A) and counterclockwise winding (4B) symmetrically wound on the base body (3). The intersection point between the clockwise winding (4A) and the counterclockwise winding (4B) wound on the finger back panel (3B) of the base body (3) is called the upper intersection point (4C); the clockwise winding (4A) The intersection point between the counterclockwise winding thread ( 4B ) and the finger bottom panel ( 3D ) of the base body ( 3 ) is called the lower intersection point ( 4D ). The winding angle between the clockwise winding (4A) and the counterclockwise winding (4B) is denoted as α, that is, α=5～15 degrees, and the interval between two adjacent clockwise windings (4A) is denoted as d, that is, d=5-20mm.

The advantages of the soft bionic finger of the present invention are:

① The soft bionic finger designed by the present invention uses gas or liquid as the pressure medium to fill the airbag (3A) in the center of the hollow base (3), and the fiber envelope layer made of the strain-limited bottom layer (30) and flexible tensile material (4) to limit the bending movement of the fingers. The action mechanism of the soft bionic finger is to confine the high-elastic continuous closed cavity composed of polymeric elastic materials to a certain shape, forming an ultra-redundant structural space, and obtaining unlimited degrees of freedom and continuous deformation capabilities.

②The closed cavity (i.e., the airbag (3A)) designed by the soft bionic finger of the present invention can realize bending actions with different curvatures and curves by setting the layout and material of the fiber envelope layer and the strain-limited bottom layer, which is called the structural "predetermined". programming" mode. The invention realizes under-actuated flexible motion by using the structure "pre-programming", thereby reducing the structural complexity of the soft humanoid finger. At the same time, the soft humanoid finger adopts a passive control strategy, which has significant advantages in terms of cost, volume, and system complexity compared with traditional bionic fingers that adopt active control methods.

③Using 3D printing technology to make the hollow matrix, and using injection molding technology to make the skin outer layer, so that the obtained soft bionic finger of the present invention has a small resistance to pressure due to the flexible material matrix, and the soft humanoid finger can absorb external impact force, And it can better adapt to the shape and size of the interactive object. At the same time, the application of flexible soft materials can make the humanoid fingers closer to the shape and texture of real fingers.

④ The material Young's model of the soft humanoid finger designed by the present invention is 250kPa, the maximum bending displacement of a single soft finger can reach 100mm, and the output force can reach 4N, which is close to the hardness of human skin.

Description of drawings

Fig. 1 is the external structure diagram of the soft humanoid finger designed by the present invention.

Fig. 1A is an external physical diagram of the soft humanoid finger designed by the present invention.

Fig. 1B is an A-A sectional view of the soft humanoid finger designed by the present invention.

Fig. 1C is an exploded view of the soft humanoid finger designed by the present invention.

Fig. 1D is a schematic diagram of the winding of the fiber envelope layer of the soft humanoid finger designed by the present invention.

Fig. 2A is a front view of the combination of the base body and the fiber envelope layer of the soft humanoid finger designed by the present invention.

Fig. 2B is a rear view of the combination of the base body and the fiber envelope layer of the soft humanoid finger designed by the present invention.

Fig. 2C is a top view of the combination of the matrix and the fiber envelope layer of the soft humanoid finger designed by the present invention.

Fig. 2D is a bottom view of the combination of the matrix and the fiber envelope layer of the soft humanoid finger designed by the present invention.

Fig. 3 is a mold structure diagram for making the soft humanoid finger designed by the present invention.

1. Outer layer of skin 1A.A through hole 2. Air duct 3. Matrix 3A. Airbag 3B. Finger upper panel 3C. Finger left panel 3D. Finger lower panel 3E. Finger right panel 30. Strain limiting layer 4. Fiber envelope 4A. Clockwise winding 4B. Counterclockwise winding 4C. Turn-in point 4D. Lower node 5A. End of finger 5B. Root of finger 6A. Upper mold 6B. Lower mold 6C. Injection parts 6C1. Injection hole 6D. End piece

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Referring to Figure 3, a multi-step molding process is used to manufacture a soft humanoid finger with structural pre-programming, including the following steps:

Step 1, making a hollow matrix;

The hollow matrix 3 is obtained by 3D printing rapid prototyping;

In the present invention, the material selected for the hollow matrix 3 is the high-performance platinum-cured silicone rubber produced by Smooth-on Company, the model is Dragon skin20 or Dragon skin10, which has good strength and elasticity and can be stretched to several digits of its original size. times without being torn, and will bounce back to its pre-stretched form without deformation.

In the present invention, the thickness of the hollow base body 3 is recorded as h3, that is, h3=1.5-5 mm.

Step 2, making the upper mold 6A;

Using 3D printing rapid prototyping to get the upper mold 6A;

In the present invention, the material selected for the upper mold is PLA (polylactic acid) material, which meets the requirements of rapid prototyping.

Step 3, making the lower mold 6B;

The lower mold 6B was obtained by 3D printing rapid prototyping;

In the present invention, the material selected for the lower mold is PLA (polylactic acid) material, which meets the requirements of rapid prototyping.

Step 4, left-handed and right-handed symmetrical winding to make fiber envelope layer;

Bond the strain-limiting layer 30 on the bottom panel of the hollow matrix 3 prepared in step 1, and then use clockwise and counterclockwise to wind the flexible and tensile Kevlar wire symmetrically to obtain fibers enveloped in the hollow matrix 3 and the strain-limiting layer 30 Above, called the preform. The fiber envelope formed by winding the Kevlar wire constitutes the fiber envelope layer 4 .

Referring to Fig. 2D, the winding angle between the clockwise winding 4A and the counterclockwise winding 4B is marked as α (that is, α = 5-15 degrees), and the interval between two adjacent clockwise windings 4A is marked as d (ie d=5-20mm), or the interval between two adjacent counterclockwise windings 4B is denoted as d (ie d=5-20mm). The clockwise winding 4A and the counterclockwise winding 4B use flexible and tensile Kevlar wires with a diameter of 0.5-1.5 mm.

Step 5: Injection molding to make a soft humanoid finger;

Install the preform obtained in Step 4 into the upper and lower molds prepared in Step 2 and Step 3, and inject the platinum-cured silicone rubber through the injection hole 6C1 of the injection part 6C; remove the mold after curing at normal temperature, and obtain the soft body Humanoid fingers.

Referring to Fig. 1, Fig. 1A, Fig. 1B, and Fig. 1C, a soft humanoid finger with structural pre-programming designed by the present invention includes a hollow matrix 3, a strain limiting layer 30, a fiber package Cortex 4, outer layer of skin 1 and airflow conduit 2.

One end of the soft humanoid finger is the finger end 5A, and the other end is the finger root 5B. The airflow conduit 2 is installed on the base of the finger 5B.

The bottom panel of the hollow matrix 3 is bonded with a strain limiting layer 30 and wound clockwise to form a fiber enveloping layer 4 . The fiber enveloping layer 4 is made between the hollow matrix 3 , the strain limiting layer 30 and the outer skin layer 1 .

Referring to Fig. 1A, in order to describe in detail the present invention, a soft humanoid finger with pre-programmed structure is designed. method to obtain the rest of the finger morphology. The length of the soft humanoid finger is recorded as b (ie b=25(h1+h3)~50(h1+h3)). The outer skin layer 1 and the hollow matrix 3 are made of the same material, such as the high-performance platinum-cured silicone rubber produced by Smooth-on Company, the model is Dragon skin20 or Dragon skin10, which has good strength and elasticity and can be stretched to its original Multiple times its size without being torn, and will bounce back to its pre-stretched form without deformation. The thickness of the outer skin layer 1 is recorded as h1, that is, h1=1.5-5mm. The thickness of the hollow matrix 3 is recorded as h3, that is, h3=1.5-5mm. Since the thickness of the strain limiting layer 30 is 0.5-1 mm, it can be ignored when calculating the bending deformation of the finger.

Referring to FIG. 1B , the base body 3 is a hollow structure, that is, the middle part of the base body 3 is an air bag 3A (or a sealed cavity), and the air bag 3A is used to store gas with a constant pressure, and the gas enters through the gas flow conduit 2 . Referring to Fig. 2A, Fig. 2B, Fig. 2C, shown in Fig. 2D, the top of base body 3 is finger back panel 3B, the bottom of base body 3 is finger bottom panel 3D, one side of base body 3 is finger left panel 3C, the other side of base body 3 One side is finger right panel 3E. The strain limiting layer 30 is glued on the finger bottom panel 3D, the thickness of the strain limiting layer 30 is 0.5-1 mm, and the strain limiting layer 30 is made of glass fiber. In the present invention, the material selected for the matrix 3 is high-performance platinum-cured silicone rubber produced by Smooth-on Company, the model is Dragon skin20 or Dragon skin10, which has good strength and elasticity and can be stretched to several times its original size without being torn, and will bounce back to its pre-stretched form without deformation.

Referring to FIG. 1C , FIG. 2A , FIG. 2B , FIG. 2C and FIG. 2D , the fiber envelope layer 4 is composed of a clockwise winding 4A and a counterclockwise winding 4B symmetrically wound on the base 3 . The intersection point between the clockwise winding 4A and the counterclockwise winding 4B wound on the finger back panel 3B of the base 3 is called the upper intersection point 4C; the clockwise winding 4A and the counterclockwise winding 4B are wound on the base 3 The junction point on the bottom panel 3D of the fingers is called the lower node 4D. Referring to Fig. 2D, the winding angle between the clockwise winding 4A and the counterclockwise winding 4B is marked as α (that is, α = 5-15 degrees), and the interval between two adjacent clockwise windings 4A is marked as d (ie d=5-20mm), or the interval between two adjacent counterclockwise windings 4B is denoted as d (ie d=5-20mm). The clockwise winding 4A and the counterclockwise winding 4B use flexible and tensile Kevlar wires with a diameter of 0.5-1.5 mm.

Deformation conditions of the soft bionic finger:

In the present invention, the action mechanism of the soft bionic finger: Confining the high-elastic continuous closed cavity composed of polymeric elastic materials to a certain shape, forming a super-redundant structural space, that is, the airbag 3A, to obtain unlimited degrees of freedom and continuous Shapeshifting ability. When gas or liquid is injected, the airbag 3A expands as much as possible along the axial direction and the radial direction like a balloon. When the airbag 3A is added with a fiber envelope with a small expansion coefficient along the axial direction, the radial deformation of the airbag 3A is limited, and it can only expand along the axial direction, which is no longer a purposeless extension equivalent to the expansion and contraction of the airbag 3A sports. When a layer of strain limiting bottom layer (finger bottom panel 3D) with a small expansion coefficient is added on one side of the airbag 3A, the axial expansion deformation of the corresponding side of the airbag 3A is restricted. In this way, when the internal pressure of the airbag 3A rises, there is a difference in the degree of expansion and deformation on both sides of the axis, which will cause the airbag 3A to produce a bending movement as a whole. Thus, the airbag 3A can achieve bending actions with different curvatures and curves by setting the layout and materials of the fiber envelope layer and the strain-limiting bottom layer, that is, the underactuated flexible motion is realized in a structural "preprogrammed" manner, thereby reducing the structural complexity. At the same time, the soft humanoid finger adopts a passive control strategy, which has significant advantages in terms of cost, volume, and system complexity compared with traditional bionic fingers that adopt active control methods. Since the flexible material matrix has little resistance to pressure, the soft humanoid finger can absorb external impact and better adapt to the shape and size of the interactive object. At the same time, the application of flexible soft materials can make the humanoid finger closer to the shape and texture of the real finger, greatly improving its interaction experience with the external environment.

In the present invention, in order to realize the deformation of the soft bionic finger, the pressure of the gas or liquid filled in the air bag 3A of the hollow base body 3 is 20-200kPa, and the length b of the finger is 25-50 times of the thickness h1+h3 (i.e. b=25(h1+h3)˜50(h1+h3)).

Example 1

Designed the right index finger as shown in Figure 1A, the length of the right index finger is b=112mm, the thickness of the right index finger is 4mm (i.e. h1+h3=4mm, matrix wall thickness 2mm, skin glue layer wall thickness 2mm), α=6 degree, the interval between two adjacent clockwise winding wires 4A is d=5mm.

Install the base 5B of the soft humanoid right finger on a bracket, and the axis in the length direction of the finger is parallel to the Y-axis of the six-axis force sensor (Mini 40F/T sensor, ATI, USA), and the end of the finger 5A is located on the force sensor The origin is directly above. The pressure sensor (ISE40-C6-22L-M, SMC, Japan) can measure and display the pressure in the closed cavity of the finger matrix core in real time. The force data of the finger acting on the force sensor will be collected by a computer data board (PCI-6284, National Instruments, USA), and processed and recorded by the compiled LabVIEW host computer software program. The dynamic performance test was carried out under the condition of applying different constant pressures (60KPa, 120KPa, 180KPa), and the deformation of the bionic right finger was satisfied.

By relying on the design of the real human index finger for the soft humanoid right finger obtained in Example 1, the feasibility of its bending motion mechanism is verified under the pressure medium of gas, and the bending motion performance and dynamic performance of the finger are compared with each other through experiments. The relationship between the control gas pressure was explored. Experimental results show that the Young's model of the soft finger material is 250kPa, which is close to the hardness of human skin. The maximum bending displacement of a single soft finger can reach 100mm, and the output force can reach 4N.

The soft humanoid finger designed by the present invention is based on the research on the structural properties, action mechanism and motion performance of biological soft tissue, and a new type of pneumatic soft humanoid finger is designed. Compared with the traditional rigid humanoid finger, the humanoid finger has the appearance size and texture similar to that of a real human finger, and also has the advantages of simple structure, fast manufacturing, low cost, impact cushioning, safe interaction and easy control. These advantages benefit from the use of flexible materials and structures throughout the entire finger, rather than traditional hard plastics and metals. The rapid and low-cost manufacturing of soft humanoid fingers makes them suitable for the operation of high-risk industries and the personal customization of future bionic robots. At the same time, the inherent safety of the soft bionic finger greatly improves its interaction experience with external environmental objects (such as people, animals, fragile objects, etc.).

Claims (7)

1. A soft humanoid finger, comprising a hollow base (3), an outer layer of skin (1) and an airflow duct (2); one end of the soft humanoid finger is a finger end (5A), and the other end is a finger tip (5A). root (5B); the airflow conduit (2) is installed on the root of the finger (5B); it is characterized in that: it also includes a strain limiting layer (30) and a fiber envelope layer (4); the bottom panel of the hollow matrix (3) After the strain-limiting layer (30) is bonded on the top, the fiber enveloping layer (4) is formed by winding clockwise and counterclockwise; the fiber enveloping layer (4) is between the matrix (3) and the outer skin layer (1); The network layer (4) is composed of a clockwise winding (4A) and a counterclockwise winding (4B) symmetrically wound on the base (3); between the clockwise winding (4A) and the counterclockwise winding (4B) The intersecting point wound on the finger back plate (3B) of the base body (3) is called the upper intersection point (4C); the clockwise winding (4A) and the counterclockwise winding (4B) are wound on the base (3) The intersection point on the bottom panel of the finger (3D) is called the lower node (4D); the winding angle between the clockwise winding (4A) and the counterclockwise winding (4B) is recorded as α, that is, α=5～15 degree, the interval between two adjacent clockwise windings (4A) is recorded as d, that is, d=5-20mm. 2. The soft humanoid finger according to claim 1, characterized in that: the thickness of the skin outer layer (1) is recorded as h1, i.e. h1=1.5～5mm, and the thickness of the hollow matrix (3) is recorded as h3, i.e. h3 = 1.5-5mm, the thickness of the strain-limiting layer (30) is 0.5-1mm, and the length of the soft humanoid finger is denoted as b, that is, b=25(h1+h3)-50(h1+h3). 3 . The soft humanoid finger according to claim 1 , characterized in that: the clockwise winding ( 4A ) and the counterclockwise winding ( 4B ) use flexible tensile Kevlar wires with a diameter of 0.5-1.5 mm. 4. The soft humanoid finger according to claim 1, characterized in that: the material selected for the skin outer layer (1) and the hollow matrix (3) is platinum-cured silicone rubber. 5. The soft humanoid finger according to claim 1, characterized in that: the Young's modulus of the soft finger material is 250kPa, which is close to the hardness of human skin; the maximum bending displacement of a single soft finger is 100mm, and the output force is 4N. 6. A method for preparing the soft humanoid finger according to claim 1, characterized in that it comprises the following steps: Step 1, making a hollow matrix; The hollow matrix (3) is obtained by 3D printing rapid prototyping; Step 2, making the upper mold (6A); The upper mold (6A) is obtained by 3D printing rapid prototyping; Step 3, making the lower mold (6B); 3D printing rapid prototyping is used to obtain the lower mold (6B); Step 4, left-handed and right-handed symmetrical winding to make fiber envelope layer; Bond the strain-limiting layer (30) on the bottom panel of the hollow matrix (3) obtained in step 1, and then use clockwise and counterclockwise to wind the flexible and tensile Kevlar wire symmetrically to obtain fibers enveloped in the hollow matrix (3 ), called a preform; The winding angle between the clockwise winding (4A) and the counterclockwise winding (4B) is marked as α, that is, α=5～15 degrees, two adjacent clockwise windings (4A) or counterclockwise windings ( 4B) The interval between them is recorded as d, that is, d=5~20mm; Step 5: Injection molding to make a soft humanoid finger; Install the preform obtained in Step 4 into the upper and lower molds prepared in Step 2 and Step 3, and inject the platinum-cured silicone rubber through the injection hole (6C1) of the injection part (6C); model to obtain soft humanoid fingers. 7. The soft humanoid finger made by the method according to claim 6 is characterized in that: the Young's modulus of the soft finger material is 250kPa, which is close to the hardness of human skin; the maximum bending displacement of a single soft finger is 100mm, and the output force is 4N .