Three-degree-of-freedom antagonistic joint driven by biomimetic muscle

Abstract

The application discloses a three-degree-of-freedom antagonistic joint driven by a bionic muscle, which comprises an upper joint base, a locking baffle, a fixed block, a spring, a fixed ring, a straight-pulling bionic muscle, a lower joint base and a cable-stayed bionic muscle; the joint compactly integrates three active degrees of freedom in a spherical hinge joint, and can greatly reduce the volume and mass of the three-degree-of-freedom joint; and the spring and the bionic muscle form an antagonistic driving relationship, so that the restoring force of the spring can ensure that the joint can return to the initial state more quickly when the bionic muscle is elongated, and the problem that elongation cannot generate thrust to ensure that the joint can quickly return to the original position is solved.

Description

Technical Field

[0001] This invention relates to robot joint systems, specifically a three-degree-of-freedom antagonistic joint based on biomimetic muscle actuation. Background Technology

[0002] In recent years, robots have been increasingly used in environmental detection, material transportation, military reconnaissance, and home services. Among them, gecko-inspired adhesive crawling robots, due to the adhesive properties of their feet, have the ability to freely navigate on various surfaces (smooth / rough, hard / soft, flat / curved), and are gradually being applied to tasks such as on-orbit inspection of high-value spacecraft. Ordinary robots have point contact between their feet and the supporting surface, so their legs only need to meet positional requirements; however, the feet of adhesive crawling robots need to ensure that the adhesive surface is parallel to the supporting surface, and their legs have at least six degrees of freedom, three of which are located at the ankle joint, requiring them to meet positional and posture requirements.

[0003] Traditional robot joints consist of motors, reducers, and sensors. To achieve the three degrees of freedom in an ankle joint, these three joints must be connected in series, resulting in a bulky and heavy ankle joint that is unsuitable for smaller adhesive crawling robots. Biomimetic muscles, a novel intelligent actuation material, resemble a rope in shape. They can actively contract and recover by controlling an external electric field. The tension generated during contraction serves as the joint's actuation source, replacing traditional robot joint motors and achieving three degrees of freedom integration in a very small volume and mass. Summary of the Invention

[0004] The present invention aims to solve the problem of how to integrate the three active degrees of freedom of a robot joint in a lightweight and compact manner.

[0005] To address the above problems, this invention provides a three-degree-of-freedom antagonistic joint based on biomimetic muscle actuation, comprising:

[0006] The base assembly includes an upper joint base and a lower joint base. The central area of ​​the opposing surfaces of the two bases is provided with a spherical groove and a spherical body that cooperate to form a ball joint. Four bionic muscle fixation seats are provided between the upper joint base and the lower joint base, distributed around the ball joint and facing the four sides of the base assembly.

[0007] Four sets of straight-pull bionic muscles are located on the four sides of the base assembly, each connected between the upper and lower joint bases. Among them, the first and third straight-pull bionic muscles, which are arranged opposite each other, cooperate in their extension and contraction states to drive the first degree of freedom rotation of the antagonistic joint. The other two sets of second and fourth straight-pull bionic muscles, which are arranged opposite each other, cooperate in their extension and contraction states to drive the second degree of freedom rotation of the antagonistic joint.

[0008] Eight groups of diagonal pull bionic muscles are located between the upper and lower joint bases, each connected from a corner of the base assembly to a corresponding bionic muscle fixation seat. Two corners on each side of the base assembly, corresponding to the bionic muscle fixation seat facing that side, are used to fix two groups of diagonal pull bionic muscles respectively. The eight groups of diagonal pull bionic muscles are divided into two drive groups: one drive group jointly drives one rotational direction of the third degree of freedom of the antagonistic joint, and the other drive group jointly drives another rotational direction of the third degree of freedom. Each group of diagonal pull bionic muscles and its adjacent group are in different drive groups.

[0009] Four springs are located at the four corners of the base assembly, each connected between the upper joint base and the lower joint base. In the initial state, the springs, the straight-pull bionic muscle, and the oblique-pull bionic muscle are all in their original lengths, and the upper joint base and the lower joint base are arranged in parallel. The first degree of freedom and the second degree of freedom are parallel to the upper joint base and the lower joint base, and the third degree of freedom is perpendicular to the upper joint base and the lower joint base.

[0010] Furthermore, the upper base of the joint has four spring mating grooves to fix one end of each spring; the lower base of the joint has four column shafts, each column shaft having a mating groove at its center to fix the other end of each spring.

[0011] Furthermore, the lower base of the joint has four fixing rings corresponding to four column shafts; the outer side of each column shaft slides into the inner side of a corresponding fixing ring to form a sliding bearing.

[0012] Furthermore, the four bionic muscle fixing seats respectively fix one end of each group of diagonal stretch bionic muscles near the center of the base assembly;

[0013] The outer sides of the four fixing rings are used to fix the end of each group of inclined pull bionic muscles near the corner of the base assembly; each fixing ring connects to two groups of inclined pull bionic muscles corresponding to its corner, and these two groups of inclined pull bionic muscles are respectively connected to two bionic muscle fixing seats near that corner.

[0014] Furthermore, when the first and third straight-pull bionic muscles are electrically energized, the first degree of freedom has two opposite rotational directions, wherein:

[0015] When the first straight-pull bionic muscle contracts due to electrical current, the third straight-pull bionic muscle is stretched, the first and fourth springs on both sides of the first straight-pull bionic muscle are compressed, the second and third springs on the opposite side are stretched, and the antagonistic joint rotates around the first direction of the first degree of freedom.

[0016] When the first straight-pull bionic muscle is de-energized, the restoring force generated by the third straight-pull bionic muscle and the four springs when they return to their original lengths causes the first degree of freedom to return to its initial state.

[0017] When the third straight-pull bionic muscle contracts due to electrical current, the first straight-pull bionic muscle is stretched, the second and third springs on both sides of the third straight-pull bionic muscle are compressed, the first and fourth springs on the opposite side are stretched, and the antagonistic joint rotates in the second direction around the first degree of freedom.

[0018] When the third straight-pull bionic muscle is de-energized, the restoring force generated by the first straight-pull bionic muscle and the four springs as they return to their original lengths causes the first degree of freedom to return to its initial state.

[0019] Furthermore, when the second and fourth straight-pull bionic muscles are energized, the second degree of freedom has two opposite rotational directions, wherein:

[0020] When the second straight-pull bionic muscle contracts due to electrical current, the fourth straight-pull bionic muscle is stretched. The first and second springs on both sides of the second straight-pull bionic muscle are compressed, while the third and fourth springs on the opposite side are stretched. The antagonistic joint rotates around the first direction of the second degree of freedom.

[0021] When the second straight-pull bionic muscle is de-energized, the second degree of freedom returns to its initial state through the restoring force generated by the fourth straight-pull bionic muscle and the four springs when they return to their original length.

[0022] When the fourth straight-pull bionic muscle contracts due to electrical current, the second straight-pull bionic muscle is stretched, the third and fourth springs located on both sides of the fourth straight-pull bionic muscle are compressed, the first and second springs on the opposite side are stretched, and the antagonistic joint rotates in the second direction around the second degree of freedom.

[0023] When the fourth straight-pull bionic muscle is de-energized, the second degree of freedom returns to its initial state through the restoring force generated when the second straight-pull bionic muscle and the four springs return to their original lengths.

[0024] Furthermore, at the first corner of the base assembly, one end of each of the first and eighth oblique stretch bionic muscles is connected.

[0025] The second corner of the base assembly is connected to one end of the second and third oblique pull bionic muscles, respectively.

[0026] The third corner of the base assembly is connected to one end of the fourth and fifth oblique stretch bionic muscles, respectively.

[0027] The fourth corner of the base assembly is connected to one end of the sixth and seventh oblique stretch bionic muscles, respectively.

[0028] The first side of the base assembly is between the first corner and the second corner, and the first bionic muscle fixing seat faces the first side, respectively connecting the other ends of the first oblique stretch bionic muscle and the second oblique stretch bionic muscle;

[0029] The second side of the base assembly is between the second corner and the third corner, and the second bionic muscle fixing seat faces the second side, respectively connecting the other ends of the third oblique stretch bionic muscle and the fourth oblique stretch bionic muscle;

[0030] The third side of the base assembly is between the third corner and the fourth corner, and the third bionic muscle fixing seat faces the third side, respectively connecting to the other end of the fifth oblique stretch bionic muscle and the sixth oblique stretch bionic muscle.

[0031] The fourth side of the base assembly is between the fourth corner and the first corner, and the fourth bionic muscle fixing seat faces the fourth side, respectively connecting the other ends of the seventh oblique stretch bionic muscle and the eighth oblique stretch bionic muscle.

[0032] Furthermore, the first, third, fifth, and seventh oblique pull bionic muscles belong to the first drive group;

[0033] The second, fourth, sixth, and eighth oblique pull bionic muscles belong to the second drive group.

[0034] When the two drive groups of the diagonal pull bionic muscle are electrically energized, the upper joint base has two opposite rotational directions relative to the lower joint base, wherein:

[0035] When the first drive group's diagonal pull bionic muscle contracts due to electrical stimulation, the second drive group's diagonal pull bionic muscle and four springs are stretched, and the third degree of freedom of the antagonistic joint rotates in the first direction.

[0036] When the first drive group of inclined pull bionic muscles is de-energized, the third degree of freedom returns to its initial state through the restoring force generated by the second drive group of inclined pull bionic muscles and the four springs when they return to their original length.

[0037] When the second drive group's diagonal pull bionic muscle contracts due to electrical stimulation, the first drive group's diagonal pull bionic muscle and four springs are stretched, and the third degree of freedom of the antagonistic joint rotates in the second direction.

[0038] When the second drive group's diagonal pull bionic muscle is de-energized, the restoring force generated by the first drive group's diagonal pull bionic muscle and the four springs returning to their original lengths causes the third degree of freedom to return to its initial state.

[0039] Furthermore, the joint base has a first set of bionic muscle fixing grooves located on the four sides of the joint base, which are used to cooperate with the four fixing blocks of the first set to fix one end of each straight-pull bionic muscle; the joint base is also equipped with four locking baffles of the first set for locking the four fixing blocks of the first set.

[0040] Furthermore, the joint base has a second set of bionic muscle fixing grooves located on the four sides of the joint base, which are used to cooperate with the four fixing blocks of the second set to fix the other end of each straight-pull bionic muscle; the joint base is also equipped with four locking baffles of the second set for locking the four fixing blocks of the second set.

[0041] Compared with existing technologies, the three-degree-of-freedom antagonistic joint based on biomimetic muscle drive described in this invention has the following advantages:

[0042] (1) Integrating three active degrees of freedom into a single ball joint can significantly reduce the volume and mass of the three-degree-of-freedom joint.

[0043] (2) Since flexible bionic muscles can only contract to generate tension and cannot extend to generate thrust, the spring is used to form an antagonistic driving relationship with the bionic muscle. When the bionic muscle extends, the restoring force of the spring is used to ensure that the joint can return to the initial state more quickly when it is driven. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the composition of a three-degree-of-freedom antagonistic joint based on biomimetic muscle drive.

[0045] Figure 2 This is a schematic diagram showing the arrangement of biomimetic muscles and springs.

[0046] Figure 3 This is a schematic diagram of the base on the joint.

[0047] Figure 4 This is a schematic diagram of the base of the joint.

[0048] Figure label:

[0049] Joint base 1: Spring fitting groove 1-1, bionic muscle fixing seat 1-2, bionic muscle fixing groove 1-3, spherical groove 1-4;

[0050] Locking baffle 2, fixing block 3, fixing ring 5;

[0051] Spring 4: Springs 1 to 4, 4-1, 4-2, 4-3, 4-4;

[0052] Straight-pull bionic muscle 6: The first straight-pull bionic muscle to the fourth straight-pull bionic muscle 6-1, 6-2, 6-3, 6-4;

[0053] 7. Joint base; 7-1. 7-2. 7-3. Bionic muscle fixation groove;

[0054] Oblique pull bionic muscles 8: First oblique pull bionic muscles to eighth oblique pull bionic muscles 8-1, 8-2, 8-3, 8-4, 8-5, 8-6, 8-7, 8-8. Detailed Implementation

[0055] like Figures 1-4 As shown, the present invention provides a three-degree-of-freedom antagonistic joint based on bionic muscle drive, including an upper joint base 1, a locking baffle 2, a fixing block 3, a spring 4, a fixing ring 5, a straight-pull bionic muscle 6, a lower joint base 7, and an oblique-pull bionic muscle 8.

[0056] The upper joint base 1 has a spherical groove 1-4, which can cooperate with the spherical body 7-2 of the lower joint base 7 to form a ball joint. The spherical groove 1-4 and the spherical body 7-2 are respectively arranged in the central region of the opposite surface of the upper joint base 1 and the lower joint base 7.

[0057] The straight-pull bionic muscle 6 drives two degrees of freedom parallel to the base, while the oblique-pull bionic muscle 8 drives one degree of freedom perpendicular to the base. When an electric current is applied to the bionic muscle, it contracts and generates tension; after the power is turned off, the bionic muscle returns to its original length, but its flexibility prevents it from generating thrust. Therefore, to enable the ball joint structure to return to its original position, an additional spring 4 is needed. Springs 4 are initially all in their original length state; when a bionic muscle contracts (or stretches), springs 4 at different positions are either compressed or stretched, but all generate a restoring force towards their original length. This restoring force becomes a reaction force resisting the deformation of the bionic muscle, producing an antagonistic effect that allows the ball joint structure to return to its original position.

[0058] The upper base 1 of the joint has a spring mating groove 1-1 for fixing one end of the spring 4; the lower base 7 of the joint has a column shaft 7-1, and the center of the column shaft 7-1 has a mating groove for fixing the other end of the spring 4; the outer side of the column shaft 7-1 slides with the inner side of the fixing ring 5 to form a sliding bearing to reduce friction.

[0059] There are four springs 4 in total, specifically the first spring 4-1, the second spring 4-2, the third spring 4-3, and the fourth spring 4-4. The four spring fitting grooves 1-1 and the four column shafts 7-1 that cooperate to fix the springs 4 are respectively set at the four corners of the upper joint base 1 and the lower joint base 7.

[0060] The upper joint base 1 has a bionic muscle fixing groove 1-3, which cooperates with a set of fixing blocks 3 to fix one end of the straight-pull bionic muscle 6, so that one end of the straight-pull bionic muscle 6 is clamped between the bionic muscle fixing groove 1-3 of the upper joint base 1 and its corresponding fixing block 3. A corresponding set of locking baffles 2 is used to lock these fixing blocks 3. The lower joint base 7 has a bionic muscle fixing groove 7-3, which cooperates with another set of fixing blocks 3 to fix the other end of the straight-pull bionic muscle 6, so that the other end of the straight-pull bionic muscle 6 is clamped between the bionic muscle fixing groove 7-3 of the lower joint base 7 and its corresponding fixing block 3. A corresponding set of locking baffles 2 is used to lock these fixing blocks 3.

[0061] There are four sets of straight-pull bionic muscles 6, specifically the first straight-pull bionic muscle 6-1, the second straight-pull bionic muscle 6-2, the third straight-pull bionic muscle 6-3, and the fourth straight-pull bionic muscle 6-4. Four bionic muscle fixing grooves 1-3 are arranged on the four sides of the upper joint base 1, and four bionic muscle fixing grooves 7-3 are arranged opposite each other on the four sides of the lower joint base 7. Specifically, the first straight-pull bionic muscle 6-1 and the third straight-pull bionic muscle 6-3 are arranged opposite each other, and their extension and contraction cooperate to drive the two rotational directions of the first degree of freedom; the second straight-pull bionic muscle 6-2 and the fourth straight-pull bionic muscle 6-4 are arranged opposite each other, and their extension and contraction cooperate to drive the two rotational directions of the second degree of freedom (detailed below).

[0062] The joint base 1 has a bionic muscle fixing seat 1-2 for fixing one end of the oblique pull bionic muscle 8; the outer side of the fixing ring 5 is used to fix the other end of the oblique pull bionic muscle 8. There are a total of 8 groups of oblique pull bionic muscles 8, specifically the first oblique pull bionic muscle 8-1, the second oblique pull bionic muscle 8-2, the third oblique pull bionic muscle 8-3, the fourth oblique pull bionic muscle 8-4, the fifth oblique pull bionic muscle 8-5, the sixth oblique pull bionic muscle 8-6, the seventh oblique pull bionic muscle 8-7 and the eighth oblique pull bionic muscle 8-8.

[0063] The ball joint is surrounded by four bionic muscle fixation seats 1-2 facing four directions. In this example, the upper joint base 1 has an annular protrusion surrounding the spherical groove 1-4; the four bionic muscle fixation seats 1-2 extend further outward in the four directions of the annular protrusion, respectively facing the directions of the four bionic muscle fixing grooves 1-3. The annular protrusion and the four bionic muscle fixation seats 1-2 have a certain height. After the spherical body 7-2 enters the spherical groove 1-4 to form a ball joint, the annular protrusion and the four bionic muscle fixation seats 1-2 are located between the opposing surfaces of the upper joint base 1 and the lower joint base 7. Four fixing posts 5 are located at the four corners of the lower joint base 7; each bionic muscle fixation seat 1-2 corresponds to two adjacent fixing posts 5 and faces the position between these two fixing posts 5, used to fix two sets of diagonal pull bionic muscles 8.

[0064] by Figure 2 In terms of direction, in the first drive group, the first oblique pull bionic muscle 8-1, the third oblique pull bionic muscle 8-3, the fifth oblique pull bionic muscle 8-5, and the seventh oblique pull bionic muscle 8-7 are fixed to the left side of each fixed post 5 (which is also the left side of each bionic muscle fixing seat 1-2), and are used to jointly drive one rotation direction of the third degree of freedom (counterclockwise in this example); in the second drive group, the second oblique pull bionic muscle 8-2, the fourth oblique pull bionic muscle 8-4, the sixth oblique pull bionic muscle 8-6, and the eighth oblique pull bionic muscle 8-8 are fixed to the right side of each fixed post 5 (which is also the right side of each bionic muscle fixing seat 1-2), and are used to jointly drive another rotation direction of the third degree of freedom (clockwise in this example).

[0065] The three-degree-of-freedom antagonistic joint based on bionic muscle drive provided by the present invention has the spring 4, the straight-pull bionic muscle 6, and the oblique-pull bionic muscle 8 all in their original length state in the initial state, and are not subject to tension or pressure. The upper base 1 and the lower base 7 of the joint remain parallel.

[0066] When the straight-pull bionic muscle 6 on one side contracts, the two springs 4 closest to that side are compressed, while the other two springs 4 on the opposite side are stretched (for example, when the second straight-pull bionic muscle 6-2 contracts, the first and second springs 4-1 and 4-2 closest to that side are compressed, while the third and fourth springs 4-3 and 4-4 furthest from that side are stretched). When the two springs 4 on one side are compressed, such as when the first and second springs 4-1 and 4-2 are compressed, the second, third, fourth, and fifth oblique-pull bionic muscles 8-2, 8-3, 8-4, and 8-5 connected to these two springs 4 (4-1 and 4-2) are all in a relaxed state (hanging down), while the first, sixth, seventh, and eighth oblique-pull bionic muscles 8-1, 8-6, 8-7, and 8-8 on the opposite side are all in a stretched state.

[0067] When the lower joint base 7 is fixed, when one of the oblique pull bionic muscles 8 of a certain drive group (such as the second, fourth, sixth, and eighth oblique pull bionic muscles 8-2, 8-4, 8-6, and 8-8) is energized and contracts, the upper joint base 1 can rotate in one direction relative to the lower joint base 7. At this time, the four springs 4 (4-1, 4-2, 4-3, and 4-4) will be in a stretched state. After the oblique pull bionic muscle 8 of this drive group is de-energized, the four springs 4 are released, return to their original length, and drive the ball joint structure back to its original position. When the oblique pull bionic muscle 8 of another drive group (such as the first, third, fifth, and seventh oblique pull bionic muscles 8-1, 8-3, 8-5, and 8-7) is energized and contracts, the upper joint base 1 can rotate in the opposite direction to the lower joint base 7; at this time, the four springs 4 (4-1, 4-2, 4-3, and 4-4) will also be in a stretched state; after the oblique pull bionic muscle 8 of this drive group is de-energized, the four springs 4 are released, return to their original length, and drive the ball joint structure back to its original position.

[0068] Specifically, when driving the first degree of freedom of the three-degree-of-freedom antagonistic joint to rotate, the first straight-pull bionic muscle 6-1 needs to be energized, causing it to contract and the antagonistic joint to rotate in one direction around the first degree of freedom. At this time, the first and fourth springs 4-1 and 4-4 on both sides of the first straight-pull bionic muscle 6-1 are compressed, while the second and third springs 4-2 and 4-3 on the opposite side are stretched. The other three straight-pull bionic muscles 6-2, 6-3, and 6-4 are not energized and do not move (they are all passive): the opposite third straight-pull bionic muscle 6-3 is stretched; while the parts of the second and fourth straight-pull bionic muscles 6-2 and 6-4 that are close to the first straight-pull bionic muscle 6-1 are relaxed, and the parts that are far away from the first straight-pull bionic muscle 6-1 are stretched. When it is necessary to return to the original state, the power is cut off to the first straight-pull bionic muscle 6-1 and it is restored to its original length. Under the restoring force of the previously stretched third straight-pull bionic muscle 6-3 and the four springs 4 (the previously compressed first and fourth springs 4-1 and 4-4, and the previously stretched second and third springs 4-2 and 4-3), the first degree of freedom returns to the initial zero position.

[0069] To drive the first degree of freedom to rotate in the opposite direction, the third straight-pull bionic muscle 6-3 needs to be energized to contract; then the state of each spring 4 is reversed; the opposing first straight-pull bionic muscle 6-1 is stretched. After the third straight-pull bionic muscle 6-3 is de-energized, under the restoring force of the first straight-pull bionic muscle 6-1 and each spring 4, the degree of freedom returns to its initial zero position.

[0070] Similarly, to drive the rotation of the second degree of freedom of the three-degree-of-freedom antagonistic joint, if the second straight-pull bionic muscle 6-2 is energized to contract, the opposing fourth straight-pull bionic muscle 6-4 is stretched; the first and second springs 4-1 and 4-2 on both sides of the second straight-pull bionic muscle 6-2 are compressed, and the third and fourth springs 4-3 and 4-4 on the opposite side are stretched, causing the antagonistic joint to rotate around one direction of the second degree of freedom; when it is necessary to return to the original state, the second straight-pull bionic muscle 6-2 is de-energized to restore it to its original length; then, the previously stretched fourth straight-pull bionic muscle 6-4, the previously compressed first and second springs 4-1 and 4-2, and the previously stretched third and fourth springs 4-3 and 4-4 all generate restoring forces, causing the second degree of freedom of the antagonistic joint to return to its initial state.

[0071] Conversely, if the second degree of freedom is to be driven to rotate in the opposite direction, an electric current is applied to the fourth straight-pull bionic muscle 6-4 to cause it to contract. The state of each spring 4 is then opposite to the state of the spring 4 when the second straight-pull bionic muscle 6-2 is contracted. When the fourth straight-pull bionic muscle 6-4 contracts, the opposing second straight-pull bionic muscle 6-2 is stretched. After the fourth straight-pull bionic muscle 6-4 is de-energized, the second degree of freedom returns to its initial zero position under the restoring force of the second straight-pull bionic muscle 6-2 and each spring 4.

[0072] To drive the third degree of freedom perpendicular to the joint base in this three-degree-of-freedom antagonistic joint, if the second, fourth, sixth, and eighth oblique stretching bionic muscles 8-2, 8-4, 8-6, and 8-8 are energized and contracted, then the other first, third, fifth, and seventh oblique stretching bionic muscles 8-1, 8-3, 8-5, and 8-7 are stretched, and each of the springs 4 (4-1, 4-2, 4-3, and 4-4) is also stretched, causing the third degree of freedom perpendicular to the joint base to rotate in one direction (as shown in the attached diagram). Figure 2 From the perspective of rotation, it is clockwise at this point. When it is necessary to return to the original state, the second, fourth, sixth, and eighth oblique stretch bionic muscles 8-2, 8-4, 8-6, and 8-8 are de-energized, and they return to their original length. The first, third, fifth, and seventh oblique stretch bionic muscles 8-1, 8-3, 8-5, and 8-7, which were previously stretched, as well as the various stretched springs 4, are released. The resulting restoring force causes the third degree of freedom to return to the initial state.

[0073] Conversely, to drive the third degree of freedom to rotate in the opposite direction, the first, third, fifth, and seventh oblique pull bionic muscles 8-1, 8-3, 8-5, and 8-7 are energized and contracted, while the second, fourth, sixth, and eighth oblique pull bionic muscles 8-2, 8-4, 8-6, and 8-8 are stretched; the four springs 4 (4-1, 4-2, 4-3, and 4-4) are also stretched. When the first, third, fifth, and seventh oblique pull bionic muscles 8-1, 8-3, 8-5, and 8-7 are de-energized, the previously stretched second, fourth, sixth, and eighth oblique pull bionic muscles 8-2, 8-4, 8-6, and 8-8, as well as the four stretched springs 4, are released, and the resulting restoring force causes the third degree of freedom to return to its initial state.

[0074] In summary, this joint can compactly integrate three active degrees of freedom into a single ball joint, significantly reducing the volume and mass of a three-degree-of-freedom joint. Furthermore, by utilizing a spring to form an antagonistic driving relationship with the bionic muscle, the restoring force of the spring ensures that the joint can return to its initial state more quickly when driven by the bionic muscle during extension, thus solving the problem that extension cannot generate thrust and therefore cannot guarantee the joint's rapid return to its original position.

[0075] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A three-degree-of-freedom antagonistic joint based on biomimetic muscle drive, characterized in that, Include: The base assembly includes an upper joint base and a lower joint base. The central area of ​​the opposing surfaces of the two bases is provided with a spherical groove and a spherical body that cooperate to form a ball joint. Four bionic muscle fixation seats are provided between the upper joint base and the lower joint base, distributed around the ball joint and facing the four sides of the base assembly. Four sets of straight-pull bionic muscles are located on the four sides of the base assembly, each connected between the upper and lower joint bases. Among them, the first and third straight-pull bionic muscles, which are arranged opposite each other, cooperate in their extension and contraction states to drive the first degree of freedom rotation of the antagonistic joint. The other two sets of second and fourth straight-pull bionic muscles, which are arranged opposite each other, cooperate in their extension and contraction states to drive the second degree of freedom rotation of the antagonistic joint. Eight groups of diagonal pull bionic muscles are located between the upper and lower joint bases, each connected from a corner of the base assembly to a corresponding bionic muscle fixation seat. Two corners on each side of the base assembly, corresponding to the bionic muscle fixation seat facing that side, are used to fix two groups of diagonal pull bionic muscles respectively. The eight groups of diagonal pull bionic muscles are divided into two drive groups: one drive group jointly drives one rotational direction of the third degree of freedom of the antagonistic joint, and the other drive group jointly drives another rotational direction of the third degree of freedom. Each group of diagonal pull bionic muscles and its adjacent group are in different drive groups. Four springs are located at the four corners of the base assembly, each connected between the upper joint base and the lower joint base. In the initial state, the springs, the straight-pull bionic muscle, and the oblique-pull bionic muscle are all in their original lengths, and the upper joint base and the lower joint base are arranged in parallel. The first degree of freedom and the second degree of freedom are parallel to the upper joint base and the lower joint base, and the third degree of freedom is perpendicular to the upper joint base and the lower joint base.

2. The three-degree-of-freedom antagonistic joint as described in claim 1, characterized in that, The upper base of the joint has four spring-fitting grooves to fix one end of each spring; the lower base of the joint has four column shafts, each column shaft having a fitting groove at its center to fix the other end of each spring.

3. The three-degree-of-freedom antagonistic joint as described in claim 2, characterized in that, The joint base has four fixing rings, corresponding to four column shafts; the outer side of each column shaft slides into the inner side of a corresponding fixing ring to form a sliding bearing.

4. The three-degree-of-freedom antagonistic joint as described in claim 3, characterized in that, The four bionic muscle fixation seats fix one end of each group of diagonal stretch bionic muscles near the center of the base assembly. The outer sides of the four fixing rings are used to fix the end of each group of inclined pull bionic muscles near the corner of the base assembly; each fixing ring connects to two groups of inclined pull bionic muscles corresponding to its corner, and these two groups of inclined pull bionic muscles are respectively connected to two bionic muscle fixing seats near that corner.

5. The three-degree-of-freedom antagonistic joint as described in claim 1, characterized in that, When the first and third straight-pull bionic muscles are electrically powered, the first degree of freedom has two opposite rotational directions, among which: When the first straight-pull bionic muscle contracts due to electrical current, the third straight-pull bionic muscle is stretched, the first and fourth springs on both sides of the first straight-pull bionic muscle are compressed, the second and third springs on the opposite side are stretched, and the antagonistic joint rotates around the first direction of the first degree of freedom. When the first straight-pull bionic muscle is de-energized, the restoring force generated by the third straight-pull bionic muscle and the four springs when they return to their original lengths causes the first degree of freedom to return to its initial state. When the third straight-pull bionic muscle contracts due to electrical current, the first straight-pull bionic muscle is stretched, the second and third springs on both sides of the third straight-pull bionic muscle are compressed, the first and fourth springs on the opposite side are stretched, and the antagonistic joint rotates in the second direction around the first degree of freedom. When the third straight-pull bionic muscle is de-energized, the restoring force generated by the first straight-pull bionic muscle and the four springs as they return to their original lengths causes the first degree of freedom to return to its initial state.

6. The three-degree-of-freedom antagonistic joint as described in claim 1, characterized in that, When the second and fourth straight-pull bionic muscles are energized, the second degree of freedom has two opposite rotational directions, among which: When the second straight-pull bionic muscle contracts due to electrical current, the fourth straight-pull bionic muscle is stretched. The first and second springs on both sides of the second straight-pull bionic muscle are compressed, while the third and fourth springs on the opposite side are stretched. The antagonistic joint rotates around the first direction of the second degree of freedom. When the second straight-pull bionic muscle is de-energized, the second degree of freedom returns to its initial state through the restoring force generated by the fourth straight-pull bionic muscle and the four springs when they return to their original length. When the fourth straight-pull bionic muscle contracts due to electrical current, the second straight-pull bionic muscle is stretched, the third and fourth springs located on both sides of the fourth straight-pull bionic muscle are compressed, the first and second springs on the opposite side are stretched, and the antagonistic joint rotates in the second direction around the second degree of freedom. When the fourth straight-pull bionic muscle is de-energized, the second degree of freedom returns to its initial state through the restoring force generated when the second straight-pull bionic muscle and the four springs return to their original lengths.

7. The three-degree-of-freedom antagonistic joint as described in any one of claims 1 to 6, characterized in that, The first corner of the base assembly is connected to one end of the first inclined bionic muscle and the eighth inclined bionic muscle, respectively. The second corner of the base assembly is connected to one end of the second and third oblique pull bionic muscles, respectively. The third corner of the base assembly is connected to one end of the fourth and fifth oblique stretch bionic muscles, respectively. The fourth corner of the base assembly is connected to one end of the sixth and seventh oblique stretch bionic muscles, respectively. The first side of the base assembly is between the first corner and the second corner, and the first bionic muscle fixing seat faces the first side, respectively connecting the other ends of the first oblique stretch bionic muscle and the second oblique stretch bionic muscle; The second side of the base assembly is between the second corner and the third corner, and the second bionic muscle fixing seat faces the second side, respectively connecting the other ends of the third oblique stretch bionic muscle and the fourth oblique stretch bionic muscle; The third side of the base assembly is between the third corner and the fourth corner, and the third bionic muscle fixing seat faces the third side, respectively connecting the other ends of the fifth oblique stretch bionic muscle and the sixth oblique stretch bionic muscle. The fourth side of the base assembly is between the fourth corner and the first corner, and the fourth bionic muscle fixing seat faces the fourth side, respectively connecting the other ends of the seventh oblique stretch bionic muscle and the eighth oblique stretch bionic muscle.

8. The three-degree-of-freedom antagonistic joint as described in claim 7, characterized in that, The first, third, fifth, and seventh oblique pull bionic muscles belong to the first drive group. The second, fourth, sixth, and eighth oblique pull bionic muscles belong to the second drive group. When the two drive groups of the diagonal pull bionic muscle are electrically energized, the upper joint base has two opposite rotational directions relative to the lower joint base, wherein: When the first drive group's diagonal pull bionic muscle contracts due to electrical stimulation, the second drive group's diagonal pull bionic muscle and four springs are stretched, and the third degree of freedom of the antagonistic joint rotates in the first direction. When the first drive group's diagonal pull bionic muscle is de-energized, the third degree of freedom returns to its initial state through the restoring force generated by the second drive group's diagonal pull bionic muscle and the four springs when they return to their original length. When the second drive group's diagonal pull bionic muscle contracts due to electrical stimulation, the first drive group's diagonal pull bionic muscle and four springs are stretched, and the third degree of freedom of the antagonistic joint rotates in the second direction. When the second drive group's diagonal pull bionic muscle is de-energized, the restoring force generated by the first drive group's diagonal pull bionic muscle and the four springs returning to their original lengths causes the third degree of freedom to return to its initial state.

9. The three-degree-of-freedom antagonistic joint as described in claim 1, characterized in that, The joint base has a first set of bionic muscle fixing grooves located on the four sides of the joint base, which are used to cooperate with the four fixing blocks of the first set to fix one end of each straight-pull bionic muscle. The joint base is also equipped with four locking baffles in the first group for locking the four fixing blocks in the first group.

10. The three-degree-of-freedom antagonistic joint as described in claim 9, characterized in that, The joint base has a second set of bionic muscle fixing grooves located on the four sides of the joint base, which are used to cooperate with the four fixing blocks of the second set to fix the other end of each straight-pull bionic muscle. The lower base of the joint is also equipped with a second set of four locking baffles for locking the second set of four fixing blocks.

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