A palm based on metamorphic structure can fix axis grabbing

Abstract

The application discloses a palm capable of fixed-axis grabbing based on a metamorphic structure, and the palm is a closed chain structure which is formed by a first rod, a second rod, a third rod, a fourth rod and a fifth rod through a hinge in sequence to form a spherical five-link mechanism; a hinge is used between two adjacent links, and the hinge rotation axis passes through the spherical center of the spherical five-link mechanism; the fifth rod is connected with an external base, and the spherical five-link mechanism contains two degrees of freedom; a rotating finger base is arranged on the second rod, the third rod and the fourth rod, and the rotating axis of the rotating finger base passes through the spherical center of the spherical five-link mechanism; the finger bending direction of all the finger bases always coincides with an axis; the grabbing surface of all the fingers always passes through the spherical center when the palm is deformed, so that the pinch, grab, twist and hold postures are realized, and the action of grabbing columnar objects with different diameters is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of manipulators, in particular to a hand capable of fixed-axis grasping based on a metamorphic structure. Background Art

[0002] Currently, the palms of traditional dexterous hands are mostly non-deformable. Compared with human hands with foldable and flexible palms, traditional robotic hands and anthropomorphic hands do not have more versatility. In particular, the conventional design of fingers has three parallel joints and the fingers usually operate on a flat surface. This is the main limitation of robotic hands, resulting in limited manipulation and difficulty in adapting the hand to the geometry of the manipulated object. This also limits the fine-tuning ability and the subsequent use of robotic hands in prosthetics.

[0003] Metamorphic structure is an adaptive intelligent structure with variable topology, variable degree of freedom and variable structure. On the basis of traditional mechanism, some elements of metamorphic mechanism can be combined to design new metamorphic mechanism. In order to overcome the adverse effects of low palm flexibility on the workspace, operability and dexterity of manipulator, patent document CN102092049B discloses a humanoid dexterous hand with a palm of variable shape, which applies metamorphic mechanism to expand the degree of freedom of palm. The palm of metamorphic hand is based on a closed spherical five-bar mechanism, which can be folded and unfolded. The fingers are mounted on the rods of the spherical mechanism. The deformation of the palm can adjust the position of the root of the finger, thereby greatly increasing the reach of the finger. However, the palm fingers are fixed on the spherical five-bar linkage. When the palm is deformed, the fingers will rotate with the linkage. The rotation between the linkages of the palm directly affects the direction of the finger surface, which will cause the fingers on different linkages to face different directions, so that more than two fingers cannot reach a point at the same time, reaching an enveloping posture, which also limits the grasping ability of the manipulator.

[0004] In addition, current research on robotic arms mainly focuses on the design and drive of fingers, and there is less research on bionic dexterous palms. Summary of the Invention

[0005] The purpose of the present invention is to provide a palm that can grasp with a fixed axis based on a metamorphic structure. The palm can be equipped with four fingers and has the characteristics of variable degrees of freedom, good dexterity, large working space, and strong adaptability. At the same time, it can solve the problem that the fingers of the existing spherical five-link palm can only rotate with the connecting rod, resulting in changes in the direction of the fingers and thus affecting the grasping.

[0006] The present invention is based on the design concept of a five-link anthropomorphic dexterous hand with a morphing closed spherical surface proposed in CN 102092049 B. To address the problem of a change in the gripping surface caused by the fingers rotating with the palm when the palm is deformed, the present invention uses a simulated Hooke's hinge to redirect the rotation of the fingers when the palm is folded, so that the gripping surfaces of all fingers always remain on a single rotation axis passing through the simulated Hooke's hinge when the palm is deformed.

[0007] The technical scheme adopted by the present application is:

[0008] A palm capable of fixed-axis grabbing based on a metamorphic structure, the palm is a closed chain structure, which is composed of a first rod, a second rod, a third rod, a fourth rod and a fifth rod in sequence through hinging to form a spherical five-link mechanism. Hinges are used between two adjacent links, and the hinge rotation axis passes through the spherical center of the spherical five-link mechanism;

[0009] The fifth rod is connected to an external base, and the spherical five-link mechanism has two degrees of freedom, so two driving sources are required. In order to simplify the structure and facilitate driving, the first rod and the fourth rod are used as driving rods in this embodiment.

[0010] Rotary finger bases are arranged on the second, third and fourth rods, and the rotary axis of the rotary finger base passes through the spherical center. The finger bending surface of all finger bases always coincides on a rotation axis.

[0011] Further, the palm can be equipped with four fingers. A thumb rotary finger base is mounted on the second rod, an index finger rotary finger base is mounted on the third rod, a middle finger rotary finger base and a ring finger rotary finger base are mounted on the fourth rod. Except for the middle finger rotary finger base, the other three rotary finger bases are connected to the spherical center of the fifth rod through Z-shaped links, U-shaped shafts and pin shafts. The spherical center of the fifth rod is the same as the spherical center of the spherical five-link mechanism, and all the spherical centers below are the spherical center of the spherical five-link mechanism. Preferably, when the axis of the middle finger rotary finger base is mounted on the fourth rod, it is 90° to the rotation axis of the hinge between the fourth rod and the fifth rod.

[0012] Further, a U-shaped support is arranged at the spherical center of the fifth rod, and the upper part of the U-shaped support is a U-shaped end.

[0013] The shaft end of each rotary finger base is fixed to one end of the Z-shaped link, the other end of the Z-shaped link is connected to the middle part of the U-shaped shaft through a pin, and the two ends of the U-shaped shaft are assembled to the U-shaped end of the fifth rod through a pin shaft. The U-shaped shaft, the Z-shaped link, the pin shaft and the U-shaped end of the fifth rod connected by the three rotary finger bases form three pseudo-Hurker hinge structures, and the axes of the three pseudo-Hurker hinges are concentric with the spherical center of the spherical five-link mechanism. The sizes of the U-shaped shafts connected by the three rotary finger bases are different, and they do not interfere with each other during the deformation of the palm. The axes of the three pseudo-Hurker hinge structures coincide with each other.

[0014] When the axis of the middle finger rotary finger base is mounted on the fourth rod, it is 90° to the rotation axis of the hinge between the fourth rod and the fifth rod, so that when the fourth rod rotates, the finger bending surface of the middle finger rotary finger base always passes through the rotation axis of the pseudo-Hurker hinge. Therefore, the middle finger rotary finger base does not need to rotate and is fixed on the fourth rod.

[0015] The palm of the present application rotates through the cooperation of two driving rods, the rotation of the spherical connecting rod drives the rotation finger base to move, and the rotation finger base is connected to the spherical center through the pseudo-Hooke joint, so that the face of the rotation finger base in the bending direction always passes through the rotation axis of the pseudo-Hooke joint.

[0016] The two driving rods are connected with the two driving motors through a rope; the first rod (101) and the fourth rod (104) are provided with disc structures for winding the rope at the hinged position with the fifth rod; the fifth rod is provided with a hollow slot for the rope wiring, and the rope is connected with the driving motor through the hollow slot, so as to control the deformation of the palm.

[0017] The present application also protects a humanoid dexterous hand which uses the palm to make all the fingers keep passing through the axis of the spherical center when the palm deforms, realizes the pinch, grab, twist and grip postures, and can realize the action of grabbing different diameter columnar objects.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1. The present application has the characteristics of reconfigurable topology and variable motion characteristics of the metamorphic structure, multifunctionality, adaptability and low cost.

[0020] 2. The present application can make each finger bend towards the axis passing through the spherical center, so that all the fingers can reach the same grabbing point at the same time when the palm deforms at any position, and the enveloping property of grabbing is enhanced.

[0021] 3. The present application adopts the rope driving scheme, the driving motor can be arranged outside the palm, which greatly reduces the size of the palm and makes the integration degree of the palm higher.

[0022] 4. The present application can be matched with different types of fingers, and has good universality. DETAILED DESCRIPTION

[0023] Figure 1 It is a structural schematic view of the palm of the present application.

[0024] Figure 2 It is a single rotation finger base connection diagram of the palm of the present application.

[0025] Figure 3 It is a back view of the present application.

[0026] Figure 4 It is a schematic view of the multiple pseudo-Hooke joint fusion structure of the finger base connection of the present application.

[0027] Figure 5 It is a deformation schematic view of the present application.

[0028] Figure 6This is another variant schematic diagram of the present invention.

[0029] Figure 7 Schematic diagram of the structure of the fourth rod and the first rod in the present invention.

[0030] Figure 8 This is a schematic diagram of the fifth rod structure of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention are further described below with reference to specific embodiments.

[0032] The palm of the present invention comprises a spherical closed loop of 5 connecting rods and 3 finger directional connection chains. Figure 1 and Figure 2 As shown, the spherical five-link consists of a first rod (101), a second rod (102), a third rod (103), a fourth rod (104) and a fifth rod (105). The first rod (101) and the second rod (102) are connected by a rotating hinge (111); the second rod (102) and the third rod (103) are connected by a rotating hinge (112); the third rod (103) and the fourth rod (104) are connected by a rotating hinge (113); the fourth rod (104) and the fifth rod 105 are connected by a rotating hinge (114); and the fifth rod (105) and the first rod 101 are connected by a rotating hinge (110), thereby forming a closed chain. The axis of each hinge of the five connecting rods passes through the same sphere center. When the five connecting rods are in a plane position, the sum of the angles occupied by the third rod (103) and the fourth rod (104) is equal to the sum of the angles occupied by the first rod (101), the second rod (102) and the fifth rod, and is equal to 180 degrees. Thus, the palm can complete a folding action, thereby increasing dexterity.

[0033] The five spherical rods of the embodiment of the present invention are all fan-shaped, as shown in the following order: Figure 1 The staggered installation is shown, and the maximum outer diameter of the spherical connecting rod is 50mm. The fifth rod (105) is also the base of the palm. Since it needs to be connected to two driving rods (the first rod (101) and the fourth rod (104)), the connection is subject to greater force. Therefore, a double support is designed for the two driving rods on the fifth rod. A U-shaped support is set on the fifth rod (105). The upper part of the U-shaped support is a U-shaped end for mounting the U-shaped shaft through a pin, and the pin passes through the center of the ball of the spherical five-bar linkage.

[0034] In this embodiment, the specific angle distribution of each of the five spherical rods is as follows: the first rod (101) is 25°; the second rod (102) is 42°; the third rod (103) is 68°; the fourth rod (104) is 112°; and the fifth rod (105) is 113°. The angle distribution and size of the five rods can be adjusted according to actual conditions without much influence on the effect.

[0035] The thumb rotating finger base (106) is arranged on the second rod (102); the index finger rotating finger base (107) is arranged on the third rod (103); the middle finger base (108) and the ring finger rotating finger base (109) are arranged on the fourth rod (104). Among them, the axis of the middle finger base (108) is 90° with the axis of the hinge (114), so this middle finger base always passes through the fixed axis of the hinge, so it is fixed on the fourth rod (104) and does not need to be reoriented, so it does not need to be rotated. In addition, the axes of all finger bases pass through the ball center of the spherical five-bar linkage.

[0036] As shown in Figure 1 , the connection structures of the three (thumb rotating finger base (106), index finger rotating finger base (107), and ring finger rotating finger base (109)) finger bases that need to be rotated and the ball center of the spherical five-bar linkage are the same. Taking the connection structure of the thumb rotating finger base (109) as an example, as shown in Figure 2 , the Z-shaped connecting rod (202) and the thumb rotating finger base (106) are fixed together through two pins (201), the Z-shaped connecting rod (202) and the U-shaped shaft (203) are connected through the pin (205), and the U-shaped shaft (203) and the fifth rod (105) are assembled together through the pin shaft (204). The U-shaped shaft (203), the Z-shaped connecting rod (202), the pin shaft (204), and the fifth rod (105) constitute a pseudo-Hooke joint structure, and the axis of the pseudo-Hooke joint is concentric with the ball center of the spherical five-bar linkage.

[0037] The two required driving motors can be connected to the disc structure (701) (as shown in Figure 7 ) of the first rod (101) and the fourth rod (104) that are hinged to the fifth rod (105) through ropes, and the disc structure is provided with a circular groove for winding the ropes. The transmission ropes are transmitted to the outside through the empty slot (801) of the fifth rod and connected to the driving motor, so as to control the deformation of the palm. The driving motor is not embodied in the present application, and others can install it externally according to actual needs. Two round holes in the empty slot can be inserted into the pin shaft to enhance the wear resistance between the rope and the rod.

[0038] Similarly, the Z-shaped connecting rod, the U-shaped shaft, the pin shaft on the index finger rotating finger base (107) and the fifth connecting rod (105) constitute a pseudo-Hooke joint structure, and the Z-shaped connecting rod, the U-shaped shaft, the pin shaft on the ring finger rotating finger base (109) and the fifth connecting rod (105) constitute a pseudo-Hooke joint structure, as shown in Figure 4As shown, this structure is a fusion form of multiple Hooke's hinges, wherein the U-shaped axis (403) of the ring finger rotating finger base is located inside the U-shaped end (402) of the fifth connecting rod, the U-shaped axis (401) of the index finger rotating finger base (107) is located inside the U-shaped axis (403) of the ring finger rotating finger base, and the U-shaped axis (203) of the thumb rotating finger base (106) is located inside the U-shaped axis (401) of the index finger rotating finger base, so that the three rods can rotate around the same axis at the same time. Alternatively, the U-shaped axis of the thumb rotating finger base (106) can be set inside the U-shaped end of the fifth connecting rod, and then the index finger rotating finger base (107) and the ring finger rotating finger base (109) are set inward in sequence. The three U-shaped axes are of different sizes and do not interfere with each other during the palm deformation process.

[0039] like Figure 5 As shown, the first rod (101) and the fourth rod (104) of the driving rod rotate simultaneously, which will drive the ring finger rotating finger base (109), the index finger rotating finger base (107), and the thumb rotating finger base 106 connected thereto to rotate. A corresponding finger is installed on each finger base. By adjusting the rotation angle of the two driving rods, the structure of the palm can be changed to adapt to various operating tasks, so that the four fingers can achieve pinching, grasping, twisting, holding and other postures.

[0040] like Figure 6 As shown, if only the third rod (103) and the fourth rod (104) rotate simultaneously around the hinge axis (114) and the hinge axis (112), while the other rods remain stationary, the ring finger rotates the finger base (109), the index finger rotates the finger base (107), and the middle finger finger base (108) flips, so that the four fingers can grasp the package or object. In this position, only the rotation angle of the fourth rod is adjusted to grasp cylindrical objects of different diameters, such as bottles and cups.

[0041] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A hand capable of fixed-axis grasping based on a metamorphic structure. The hand is a closed chain structure, wherein a first link, a second link, a third link, a fourth link, and a fifth link are sequentially hinged to form a spherical five-bar linkage. Adjacent links are hinged, and the axis of rotation of the hinged links passes through the center of the sphere of the spherical five-bar linkage. The present invention is characterized by: The fifth rod is connected to the external base, and the spherical five-link includes two degrees of freedom; The second, third and fourth rods are provided with rotating finger bases, and the rotation axis of the rotating finger bases passes through the center of the spherical five-bar linkage; the surfaces of all finger bases in the finger bending direction always coincide with one axis; The palm can be equipped with four fingers, with a thumb rotating finger base mounted on the second rod, an index finger rotating finger base mounted on the third rod, and a middle finger base and a ring finger rotating finger base mounted on the fourth rod; except for the middle finger base, the other three rotating finger bases are connected to the center of the fifth rod via a Z-shaped connecting rod, a U-shaped shaft, and a pin, and this center of the ball is the same as the center of the spherical five-link rod; when the axis of the middle finger base is mounted on the fourth rod, it forms a 90-degree angle with the rotation axis of the hinge between the fourth and fifth rods; A U-shaped support is provided at the center of the fifth rod, and the upper portion of the U-shaped support is a U-shaped end; The shaft end of each rotating finger base is fixed to one end of the Z-shaped connecting rod, the other end of the Z-shaped connecting rod is connected to the middle part of the U-shaped shaft through a pin, and the two ends of the U-shaped shaft are assembled with the U-shaped end of the fifth rod through a pin shaft; the U-shaped shaft, Z-shaped connecting rod, pin shaft and U-shaped end of the fifth rod connected by the three rotating finger bases form three imitation Hooke's hinge structures, and the axis centers of the three imitation Hooke's hinges are concentric with the center of the spherical five-link; the U-shaped shafts connected by the three rotating finger bases are of different sizes, and do not interfere with each other during the deformation of the palm.

2. The palm according to claim 1, characterized in that A finger can be mounted on each finger base.

3. The palm according to claim 1, wherein: The palm can drive the fingers mounted thereon to rotate, and the bending of each finger is always toward an axis passing through the center of the ball, so that all fingers can reach the same grasping point at the same time when the palm is deformed at any position.

4. The palm according to claim 1, wherein: When the five rods are in a plane position, the sum of the angles occupied by the third rod (103) and the fourth rod (104) is equal to the sum of the angles occupied by the first rod (101), the second rod (102) and the fifth rod, and all are equal to 180°.

5. The palm according to claim 1, wherein: The five rods on the spherical surface are all fan-shaped, and the specific angle distribution of each rod on the spherical surface is as follows: the first rod (101) is 25°; the second rod (102) is 42°; the third rod (103) is 68°; the fourth rod (104) is 112°; the fifth rod (105) is 113°; the first rod (101) and the fourth rod (104) are two driving rods.

6. The palm according to claim 5, characterized in that The two driving rods are connected to the two driving motors via ropes; a disc structure for winding and installing the rope is provided at the hinged position of the first rod (101) and the fourth rod (104) with the fifth rod; an empty slot for routing the rope is provided on the fifth rod, and the rope passes through the empty slot and is connected to the driving motor, thereby controlling the deformation of the palm.

7. The palm according to claim 6, characterized in that The drive motor is arranged outside the palm.

8. A humanoid dexterous hand, characterized in that: The anthropomorphic dexterous hand uses the palm described in any one of claims 1-7, so that the grasping surfaces of all fingers always maintain an axis passing through the center of the ball when the palm is deformed, realizing pinching, grasping, twisting and holding postures, and can also realize the action of grasping cylindrical objects of different diameters.

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