Flexible robotic wrist based on parallel drive

Abstract

The invention discloses a flexible mechanical arm wrist based on a parallel driving mode, comprising an upper surface, a lower surface and three artificial muscles; for any artificial muscle, it comprises an upper cover, a lower cover and a silicone body installed between the upper cover and the lower cover; the upper cover is fixed below the upper surface, and the lower cover is fixed above the lower surface; the silicone body is cylindrical, and multiple groups of nickel-titanium memory alloy coils and two fixed plates are coated inside the silicone body; the upper and lower ends of each group of nickel-titanium memory alloy coils respectively pass through coil holes reserved in the upper cover, the upper surface and the lower cover, the lower surface, and are connected to an external circuit; the two fixed plates are both in annular shape, one of the fixed plates is equipped with multiple magnets, and the other fixed plate is equipped with multiple Hall elements, the number of magnets is the same as that of the Hall elements and they correspond one to one; a cylindrical cavity is reserved in the middle of the silicone body, and the cylindrical cavity corresponds to the hollow area of ​​the annular fixed plate, and is used together to set the wires of the Hall elements.

Description

Technical Field

[0001] The present invention relates to the technical field of soft robots, and in particular to a flexible robotic arm wrist based on a parallel driving mode. Background Art

[0002] In recent years, rigid robotic arms with high precision and high repeatability have been widely used in processing and manufacturing, post-disaster rescue, resource exploration and other fields. In order to improve the dexterity of robotic arm operations, researchers have proposed the use of robotic wrists to increase the degrees of freedom of the end effector of the robotic arm. However, traditional rigid robotic wrists are limited by the large inertia and high hardness of rigid materials, and have the pain points of large working space and low interactive safety. These pain points make it difficult for rigid robotic wrists to adapt to unstructured working environments such as agriculture, mining, and underwater (for example, reef environments, coral habitats, etc.). Therefore, it is urgent to develop a compact and interactively safe robotic wrist for unstructured constrained environments.

[0003] At present, domestic and foreign research can classify robotic wrists into the following three categories according to the driving method: (1) motor drive; (2) pneumatic drive; (3) hydraulic drive. Among them, the motor-driven robotic wrist adopts the working principle of motor transmission. Its advantages are high positioning accuracy and fast response speed, but its disadvantages are large mass and poor structural flexibility. The pneumatic / hydraulic driven robotic wrist realizes the basic movement of the robotic wrist by controlling the pneumatic / hydraulic pressure difference in the structural components of the robotic wrist. Its advantage is strong load-bearing capacity, but its disadvantage is that the driver is large in mass and volume, making it difficult to design for portability. Summary of the invention

[0004] In order to solve the problems raised in the above background technology, the technical solution adopted by the present invention is:

[0005] A flexible robotic wrist based on a parallel drive mode comprises an upper surface, a lower surface and three artificial muscles installed between the upper surface and the lower surface;

[0006] The three artificial muscles have the same structure, are parallel to each other, and are evenly distributed between the upper surface and the lower surface;

[0007] For any artificial muscle, it includes an upper cover, a lower cover and a silicone body installed between the upper cover and the lower cover;

[0008] The upper cover is fixed below the upper surface, and the lower cover is fixed above the lower surface;

[0009] The silicone body is cylindrical, and is internally coated with a plurality of groups of nickel-titanium memory alloy coils and two fixing plates;

[0010] The upper and lower ends of each group of nickel-titanium memory alloy coils pass through the coil holes reserved on the upper cover and upper surface and the lower cover and lower surface respectively, and are connected to the external circuit;

[0011] The two fixing plates are both in the shape of a ring, one of the fixing plates is mounted with a plurality of magnets, and the other fixing plate is mounted with a plurality of Hall elements, the number of the magnets is the same as the number of the Hall elements and they correspond one to another;

[0012] A cylindrical cavity is reserved in the middle of the silica gel body, and the cylindrical cavity corresponds to the hollow area of ​​the annular fixing plate, and is used together to set the wire of the Hall element.

[0013] In some embodiments, during operation, one of the upper surface and the lower surface is used to connect to the end of an external robotic arm, and the other surface is used to connect to an external robotic arm.

[0014] In some embodiments, each group of nickel-titanium memory alloy coils is formed by two coils connected in series, and the two coils are connected at the upper ends by a welding point;

[0015] Each coil is formed by winding a nickel-titanium memory alloy wire and a silicone capillary tube, and the nickel-titanium memory alloy wire is arranged inside the silicone capillary tube.

[0016] In some embodiments, three groups of nickel-titanium memory alloy coils are coated inside the silicone body, and the three groups of nickel-titanium memory alloy coils are evenly distributed.

[0017] In some embodiments, the number of the magnets and the number of the Hall elements are both three, and the three magnets are evenly distributed on the outside of one fixed plate, and the three Hall elements are evenly distributed on the outside of another fixed plate.

[0018] In some embodiments, the upper cover and the lower cover have the same structure;

[0019] The upper cover comprises a disc-shaped cover body and a hollow cylindrical connecting portion fixed at the middle of one end of the cover body, and the end of the silica gel body is arranged on the inner side of the connecting portion.

[0020] In some embodiments, the upper cover is provided with a central hole, a plurality of coil holes and a plurality of threaded holes in sequence from the inside to the outside;

[0021] The central hole corresponds to the cylindrical cavity of the silica gel body and is used for the wire of the Hall element to pass through;

[0022] The coil hole is used for the end of the nickel-titanium memory alloy coil to pass through;

[0023] The threaded hole is located on the outside of the connecting portion and is used to install bolts, thereby connecting the upper cover to the external mechanical structure;

[0024] The upper surface has the same structure as the lower surface, and the upper surface is provided with through holes corresponding to the central hole, the plurality of coil holes and the plurality of threaded holes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The flexible robotic arm wrist based on the parallel driving mode provided by the present invention has a compact structure and safe interaction; the artificial muscle is made of silicone material as the main body and is light in weight; three parallel artificial muscles can be independently controlled and have three degrees of freedom; the artificial muscle adopts a nickel-titanium memory alloy coil, and according to the principle that the length of the nickel-titanium memory alloy changes at different temperatures, the heating of the nickel-titanium memory alloy coil can be controlled by an external circuit to adjust the length of the nickel-titanium memory alloy coil, thereby automatically controlling the movement of the artificial muscle and the movement of the robotic arm wrist as a whole; after heating, the length of the nickel-titanium memory alloy coil changes, thereby causing the distance between the Hall element and the magnet to change, and the magnetic field strength changes, and the output voltage of the Hall element also changes, thereby conveniently calculating the actual length of the artificial muscle, which is conducive to the precise control of the robotic arm wrist. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the flexible robotic arm wrist in an initial state based on the parallel drive mode provided by the present invention;

[0028] Figure 2 A schematic diagram of a flexible robotic arm wrist in a bent state based on a parallel drive mode provided by the present invention;

[0029] Figure 3 This is a schematic diagram of the decomposition of artificial muscle;

[0030] Figure 4 Schematic diagram of the upper cover of the artificial muscle.

[0031] Explanation of the accompanying drawings: 10, artificial muscle; 20, upper surface; 30, lower surface; 1, upper cover; 2, nickel-titanium memory alloy coil; 3, fixing plate; 4, magnet; 5, Hall element; 6, silicone body; 7, lower cover; 8, placement track; 11, cover body; 12, connecting part; 13, threaded hole; 14, center hole; 15, coil hole. DETAILED DESCRIPTION

[0032] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following further describes how the present invention is implemented in conjunction with the accompanying drawings and specific implementation methods.

[0033] Reference Figure 1-Figure 3As shown, the present invention provides a flexible robotic arm wrist based on a parallel drive mode, comprising an upper surface 20, a lower surface 30 and three artificial muscles 10 installed between the upper surface 20 and the lower surface 30; the three artificial muscles 10 have the same structure, and the three artificial muscles 10 are parallel to each other and evenly distributed between the upper surface 20 and the lower surface 30; for any artificial muscle 10, it comprises an upper cover 1, a lower cover 7 and a silicone body 6 installed between the upper cover 1 and the lower cover 7; the upper cover 1 is fixed below the upper surface 20, and the lower cover is fixed above the lower surface 30; the silicone body 6 is cylindrical, and the inside of the silicone body 6 is covered with A plurality of groups of nickel-titanium memory alloy coils 2 and two fixing plates 3; the upper and lower ends of each group of nickel-titanium memory alloy coils 2 respectively pass through the coil holes 15 reserved in the upper cover 1, the upper surface 20 and the lower cover 7, the lower surface 30, and are connected to the external circuit; the two fixing plates 3 are both annular, one of the fixing plates 3 is equipped with a plurality of magnets 4, and the other fixing plate 3 is equipped with a plurality of Hall elements 5, the number of magnets 4 and Hall elements 5 is the same and corresponds to each other; a cylindrical cavity is reserved in the middle of the silicone body 6, and the cylindrical cavity corresponds to the hollow area of ​​the annular fixing plate 3, and is used together to set the wires of the Hall element 5.

[0034] During operation, one of the upper surface 20 and the lower surface 30 is used to connect with the end of an external robot arm, and the other surface is used to connect with an external robot hand.

[0035] Preferably, each group of nickel-titanium memory alloy coils 2 is composed of two coils connected in series, and the two coils are connected at the upper end by a welding point; each coil is formed by winding a nickel-titanium memory alloy wire and a silicone capillary, and the nickel-titanium memory alloy wire is arranged inside the silicone capillary.

[0036] Preferably, each Figure 3 In the illustrated embodiment, three groups of nickel-titanium memory alloy coils 2 are coated inside the silicone body 6 , and the three groups of nickel-titanium memory alloy coils 2 are evenly distributed.

[0037] Furthermore, the number of the magnets 4 and the number of the Hall elements 5 are both three, and the three magnets 4 are evenly distributed on the outside of one fixed plate 3 , and the three Hall elements 5 are evenly distributed on the outside of another fixed plate 3 .

[0038] Further references Figure 4 As shown, preferably, the upper cover 1 has the same structure as the lower cover 7. Taking the upper cover 1 as an example, the upper cover 1 includes a disc-shaped cover body 11 and a hollow cylindrical connecting portion 12 fixed at the middle of one end of the cover body 11, and the end of the silicone body 6 is arranged on the inner side of the connecting portion 12.

[0039] The upper cover 1 is provided with a center hole 14, a plurality of coil holes 15 and a plurality of threaded holes 13 in sequence from the inside to the outside; the center hole 14 corresponds to the cylindrical cavity of the silicone body 6, and is used for the wires of the Hall element 5 to pass through; the coil hole 15 is used for the end of the nickel-titanium memory alloy coil 2 to pass through; the threaded hole 13 is located on the outside of the connecting portion 12, and is used for installing bolts to connect the upper cover 1 to the external mechanical structure; the upper surface 20 has the same structure as the lower surface 30, and the upper surface 20 is provided with through holes corresponding to the center hole 14, the plurality of coil holes 15 and the plurality of threaded holes 13.

[0040] In a specific embodiment:

[0041] The diameter of the upper surface 20 and the lower surface 30 is 150 mm, and the thickness is 4 mm. The three artificial muscles 10 are evenly distributed at 120 degrees on a circle with a diameter of 80 mm.

[0042] For any artificial muscle 10 , the diameter of the silicone body 6 is 26 mm, the height is 80 mm, and a cylindrical cavity with a diameter of 6 mm is reserved in the center for placing the wires connected to the Hall element.

[0043] Each group of nickel-titanium memory alloy coils 1 is composed of two coils connected in series, one coil is formed by winding a nickel-titanium memory alloy wire with an outer diameter of 0.2 mm and a silicone capillary with an outer diameter of 0.8 mm and an inner diameter of 0.3 mm, with a winding diameter of 2.6 mm, a coil pitch of 2.5 mm, a number of turns of 32, and a height of 80 mm. Three groups of nickel-titanium memory alloy coils 1 are arranged in a spiral and evenly distributed at 120° on a circle with a diameter of 17 mm.

[0044] The fixing plate 3 is in the shape of a ring, with an outer diameter of 14mm and an inner diameter of 16mm; three groups of grooves are arranged on the ring of the fixing plate 3, evenly distributed at 120°, and the depth of each group of grooves is 0.3mm. Three cylindrical magnets 4 and three Hall elements 5 are evenly distributed at 120° and pasted in the corresponding grooves of the fixing plate 3; and the magnets 4 and the Hall elements 5 correspond one by one up and down, with a spacing of 4mm, and the magnets 4 and the upper cover 1 are 40mm apart.

[0045] The cover body 11 of the upper cover 1 has a diameter of 58 mm and a thickness of 4 mm. The diameter of the threaded hole 13 is 4 mm, and four threaded holes 13 are evenly distributed at 90° on a circle with a diameter of 44 mm, which are used to install bolts and then connect to the external mechanical structure. The diameter of the center hole 14 is 6 mm, which is used to pass the wire. The diameter of the coil hole 15 is 3 mm, and the two adjacent holes correspond to a group of nickel-titanium memory alloy coils 2. The three groups of coil holes 15 are evenly distributed at 120° on a circle with a diameter of 17 mm. The outer diameter of the connecting part 12 is 33 mm, the inner diameter is 26 mm, and the height is 5 mm.

[0046] The flexible robotic arm wrist based on parallel driving mode provided by the present invention has a compact structure and safe interaction; the artificial muscle 10 made of silicone material as the main body is light in weight; three parallel artificial muscles 10 can be independently controlled and have three degrees of freedom; the artificial muscle 10 adopts a nickel-titanium memory alloy coil 2, and according to the principle that the length of nickel-titanium memory alloy changes at different temperatures, the nickel-titanium memory alloy coil 2 can be heated by an external circuit to adjust the length of the nickel-titanium memory alloy coil 2, thereby automatically controlling the movement of the artificial muscle 10 and the movement of the robotic arm wrist as a whole; after heating, the length of the nickel-titanium memory alloy coil 2 changes, thereby causing the distance between the Hall element 5 and the magnet 4 to change, and the magnetic field strength changes, and the output voltage of the Hall element 5 also changes, so that the actual length of the artificial muscle 10 can be conveniently calculated, which is conducive to the precise control of the robotic arm wrist.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A flexible robotic arm based on parallel drive, characterized in that: It comprises an upper surface (20), a lower surface (30), and three artificial muscles (10) installed between the upper surface (20) and the lower surface (30); The three artificial muscles (10) have the same structure, are parallel to each other, and are evenly distributed between the upper surface (20) and the lower surface (30); Any artificial muscle (10) comprises an upper cover (1), a lower cover (7), and a silicone body (6) installed between the upper cover (1) and the lower cover (7); The upper cover (1) is fixed below the upper surface (20), and the lower cover is fixed above the lower surface (30); The silicone body (6) is cylindrical, and is internally coated with a plurality of groups of nickel-titanium memory alloy coils (2) and two fixing plates (3); The upper and lower ends of each group of nickel-titanium memory alloy coils (2) are respectively passed through coil holes (15) reserved in the upper cover (1) and the upper surface (20) and the lower cover (7) and the lower surface (30), and are connected to an external circuit; The two fixing plates (3) are both annular, a plurality of magnets (4) are mounted on one of the fixing plates (3), and a plurality of Hall elements (5) are mounted on the other fixing plate (3), wherein the number of the magnets (4) and the Hall elements (5) are the same and correspond one to another; A cylindrical cavity is reserved in the middle of the silica gel body (6), and the cylindrical cavity corresponds to the hollow area of ​​the annular fixing plate (3), and is used together to set the wire of the Hall element (5); Each group of nickel-titanium memory alloy coils (2) is composed of two coils connected in series, and the two coils are connected at the upper ends by a welding point; Each coil is formed by winding a nickel-titanium memory alloy wire and a silicone capillary tube, and the nickel-titanium memory alloy wire is arranged inside the silicone capillary tube; Three groups of nickel-titanium memory alloy coils (2) are coated inside the silicone body (6), and the three groups of nickel-titanium memory alloy coils (2) are evenly distributed and arranged in a spiral shape.

2. The flexible robotic arm based on parallel drive mode according to claim 1 is characterized in that: When in operation, one of the upper surface (20) and the lower surface (30) is used to connect to the end of an external robot arm, and the other surface is used to connect to an external robot hand.

3. The flexible robotic arm based on parallel drive mode according to claim 2 is characterized in that: The number of the magnets (4) and the number of the Hall elements (5) are both three, and the three magnets (4) are evenly distributed on the outside of one fixed plate (3), and the three Hall elements (5) are evenly distributed on the outside of another fixed plate (3).

4. The flexible robotic arm wrist based on parallel drive mode according to claim 1 is characterized in that: The upper cover (1) and the lower cover (7) have the same structure; The upper cover (1) comprises a disc-shaped cover body (11) and a hollow cylindrical connecting portion (12) fixed to the middle of one end of the cover body (11), and the end of the silicone body (6) is arranged on the inner side of the connecting portion (12).

5. The flexible robotic arm wrist based on parallel drive mode according to claim 4 is characterized in that: The upper cover (1) is provided with a central hole (14), a plurality of coil holes (15) and a plurality of threaded holes (13) in sequence from the inside to the outside; The central hole (14) corresponds to the cylindrical cavity of the silica gel body (6) and is used for allowing the wire of the Hall element (5) to pass through; The coil hole (15) is used for allowing the end of the nickel-titanium memory alloy coil (2) to pass through; The threaded hole (13) is located outside the connecting portion (12) and is used for installing bolts, thereby connecting the upper cover (1) to an external mechanical structure; The upper surface (20) and the lower surface (30) have the same structure, and the upper surface (20) is provided with through holes corresponding to the central hole (14), the plurality of coil holes (15) and the plurality of threaded holes (13).

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