Structure of robot leg

Abstract

The present invention provides a robot leg structure in which a knee joint for knee bending or knee stretching of the robot leg is connected in the form of a four-fold link assembly including two fixed links and two movable links combined together, so that an external force is distributed to contact points of each link, thereby achieving a more robust structure than a simple rotary joint structure, and the link contacts configuring a rotary axis are movable to enable the structure to secure a wider operating range than the simple rotary joint structure.

Description

Structure of the robot leg

[0001] The present invention relates to the structure of a robot leg, and more particularly, to a structure of a robot leg in which a knee joint in which knee bending or extension of a robot leg occurs is connected in the form of a four-section link by combining two fixed links and two movable links, thereby distributing an external force to the contact points of each link, thereby being more rigid than a simple rotary joint structure, and securing a wider operating range than a simple rotary joint structure as the link contact points forming the rotation axis move.

[0002] Typically, walking robots are equipped with multiple legs and various mechanisms for lifting or lowering each leg and sending or pulling it forward.

[0003] For example, the leg mechanism of a walking robot is composed of three or four rotary joints and linear actuators and rotary actuators that operate them, and allows walking and movement through repeated movements of lifting or lowering the legs and sending them forward or pulling them.

[0004] The lower limb joint structure of a conventional humanoid robot includes a first frame equipped with a first motor, a first link having one end coupled to the first motor, a joint unit having the other end of the first link rotatably coupled, a second link having one end rotatably coupled to the joint unit, and a second frame including a second motor to which the other end of the second link is coupled.

[0005] In the case of conventional humanoid robots, there was a problem that the legs were heavy and rapid movement was limited because electric motors and reducers were built into each joint as the driving sources of the leg mechanism.

[0006] For prior art, please refer to Patent No. 10-2125835 (June 17, 2020).

[0007] The purpose of the present invention is to provide a structure of a robot leg in which a knee joint in which knee bending or extension of a robot leg occurs is connected in a four-section link form by combining two fixed links and two movable links, thereby distributing external force to the contact points of each link, thereby being more rigid than a simple rotary joint structure, and securing a wider operating range than a simple rotary joint structure as the link contact points forming the rotation axis move.

[0008] The structure of a robot leg according to the present invention includes an upper member forming an upper portion above the knee of the robot leg; a lower member forming a lower portion below the knee of the robot leg; a knee joint part rotatably connecting the lower member to a lower end of the upper member; a drive motor provided in the upper member and having a rotational axis that selectively rotates in a forward or reverse direction; a nut member connected to the rotational axis of the drive motor by a bevel gear and rotating in conjunction with the rotational axis of the drive motor; and a ball screw having an upper portion rotatably connected to the nut member about a longitudinal axis and a lower portion connected to the knee joint part, and moving upward or downward depending on the rotational direction of the nut member, so that the lower member connected to the knee joint part rotates clockwise or counterclockwise, thereby causing the knee of the robot leg to bend or extend.

[0009] At this time, the upper member according to the present invention has a first link contact formed at a front edge portion of its lower portion and a second link contact formed at a rear edge portion to form a first fixed link, and its lower surface is formed as an inclined surface so that the second link contact is positioned at a position higher than the height phase of the first link contact.

[0010] And, the lower member according to the present invention has a third link contact formed at a front edge portion of the upper portion and a fourth link contact formed at a rear edge portion to form a second fixed link, and the upper surface thereof is formed as an inclined surface so that the fourth link contact is positioned at a position lower than the height phase of the third link contact.

[0011] In addition, the knee joint part according to the present invention includes an inner link member positioned between the lower end of the upper member and the upper end of the lower member, one end of which is rotatably connected to the lower front side of the upper member and the other end of which is rotatably connected to the upper rear side of the lower member, and a pair of outer link members positioned on an outer surface between the lower end of the upper member and the upper end of the lower member and rotatably connecting the lower member with respect to the lower end of the upper member.

[0012] Here, the inner link member according to the present invention has a through hole formed on one side thereof that overlaps with the first link contact point of the upper member and is rotatably connected, and a through hole formed on the other side thereof that overlaps with the fourth link contact point of the lower member and is rotatably connected, and optionally forms a first movable link that rotates about the first link contact point as an axis.

[0013] At this time, it is preferable that the inner link member according to the present invention is bent toward the lower member with the other side overlapping and connected to the fourth link contact point of the lower member in the longitudinal direction.

[0014] In addition, it is preferable that the outer link members according to the present invention have a first coupling point formed at one of three corners that overlaps and connects with the second link contact point of the upper member, a second coupling point formed at another corner that overlaps and connects with the third link contact point of the lower member, and a second movable link that selectively rotates about the first coupling point as an axis, and a third coupling point formed at another corner that connects with the left and right ends of a traction member connected to the lower end of the ball screw.

[0015]

[0016] The effects achieved by the structure of the robot leg according to the present invention are as follows.

[0017] Since the knee joint, where knee bending or extension of the robot leg occurs, is connected in the form of a four-section link combining two fixed links and two movable links, the external force is distributed to the contact points of each link, making it more rigid than a simple rotary joint structure, and since the link contact points forming the rotation axis move, a wider operating range can be secured than a simple rotary joint structure.

[0018] The rotation angle, speed, and force of the knee joint can be controlled according to the unit operating length (movement distance) of the BLDC motor and ball screw that make up the linear actuator, and by using a bevel gear to connect the disk-shaped BLDC motor perpendicular to the ball screw whose length is vertical, space efficiency can be increased, so the width of the robot leg can be designed thinly.

[0019] Fig. 1 is an exemplary diagram showing a knee extension state of a robot leg according to an embodiment of the present invention.

[0020] Figure 2 is an exemplary diagram showing a cross-section of a knee extended state according to an embodiment of the present invention.

[0021] Fig. 3 is an exemplary diagram showing a knee bending state of a robot leg according to an embodiment of the present invention.

[0022] Figure 4 is an exemplary diagram showing a state in which knee bending is maximally activated according to an embodiment of the present invention.

[0023] Fig. 5 is an exemplary diagram showing a cross-section of a knee bending state of a robot leg according to an embodiment of the present invention.

[0024] Figure 6 is an exemplary diagram showing a cross-section of a state in which knee bending is maximally activated according to an embodiment of the present invention.

[0025] Figure 7 is an exemplary diagram showing a state in which knee bending is maximally activated according to an embodiment of the present invention.

[0026] The present invention provides a structure of a robot leg, including an upper member forming an upper portion above the knee of a robot leg, a lower member forming a lower portion below the knee of the robot leg, a knee joint part rotatably connecting the lower member to a lower end of the upper member, a drive motor provided in the upper member and having a rotational axis that selectively rotates in a forward or reverse direction, a nut member connected to the rotational axis of the drive motor by a bevel gear and rotating in conjunction with the rotation of the rotational axis of the drive motor, and a ball screw having an upper end rotatably connected to the nut member about a longitudinal axis and a lower end connected to the knee joint part, and moving upward or downward depending on the rotational direction of the nut member, so that the lower member connected to the knee joint part rotates clockwise or counterclockwise, thereby causing the knee of the robot leg to bend or extend.

[0027]

[0028] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention, the terms and concepts should be interpreted in a way that conforms to the technical spirit of the present invention.

[0029] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be equivalent modified examples that can replace them at the time of this application.

[0030] The present invention relates to a structure of a robot leg in which a knee joint in which knee bending or extension of a robot leg occurs is connected in a four-section link form by combining two fixed links and two movable links, thereby distributing external force to the contact points of each link, thereby being more rigid than a simple rotary joint structure, and securing a wider operating range than a simple rotary joint structure as the link contact points forming the rotation axis move. The structure is as follows with reference to the drawings.

[0031] The structure of a robot leg according to an embodiment of the present invention with reference to FIGS. 1 to 7 includes an upper member (100), a lower member (200), a knee joint part (300), a driving motor (400), and a ball screw (410). First, the upper member (100) forms an upper part above the knee of the robot leg, has a length in the vertical direction, and first and second link contact points (101, 102) connected to the knee joint part (300) are formed at the lower end thereof.

[0032] At this time, the first link contact (101) is positioned at a front edge portion of the lower portion of the upper member (100), and the second link contact (102) is positioned at a rear edge portion of the lower portion of the upper member (100), and it is preferable that the height phase of the second link contact (102) be positioned at a higher position than the height phase of the first link contact (101).

[0033] Accordingly, the first link contact point (101) and the second link contact point (102) are formed at the lower edge portion of the upper member (100) to form the first fixed link (rocker) of the four-section link, and the lower surface of the upper member (100) is formed as an inclined surface in which the height phase of the rear side is higher than the height phase of the front side so that the height phase of the second link contact point (102) can be positioned at a higher position than the height phase of the first link contact point (101).

[0034] In addition, a driving motor (400) is provided on the upper side of the upper member (100), and the driving motor (400) provides the necessary rotational force when the lower member (200) rotates based on the lower end of the upper member (100). (Rotation that causes knee bending or knee extension)

[0035] Here, it is preferable that the first and second link contact points (101, 102) of the upper member (100) are formed as through holes so that the shaft member can penetrate and be coupled laterally.

[0036] And, the lower member (200) is connected to the lower side of the upper member (100) by the knee joint part (300). The lower member (200) forms the lower part below the knee of the robot leg, has a length in the vertical direction, and third and fourth link contact points (201, 202) connected to the knee joint part (300) are formed at the upper end thereof.

[0037] At this time, the third link contact (201) is positioned at a front corner of the lower part of the lower member (200), and the fourth link contact (202) is positioned at a rear corner of the lower part of the lower member (200), and it is preferable that the height phase of the third link contact (201) is positioned at a higher position than the height phase of the fourth link contact (202).

[0038] Accordingly, the third link contact point (201) and the fourth link contact point (202) are formed on the upper end of the lower member (200), thereby forming the second fixed link (rocker) of the four-section link, and the upper surface of the lower member (200) is formed as an inclined surface in which the height phase of the rear side is lower than the height phase of the front side so that the height phase of the third link contact point (201) is positioned higher than the height phase of the fourth link contact point (202).

[0039] Here, it is preferable that the third and fourth link contact points (201, 202) of the lower member (200) are formed as through holes so that the shaft member can penetrate and be coupled laterally.

[0040] And the knee joint part (300) that rotatably connects the lower member (200) to the lower end of the upper member (100) includes an inner link member (310) and an outer link member (320).

[0041] The inner link member (310) is connected to the shaft member so that the through hole formed at one end thereof overlaps with the first link contact point (101) of the upper member (100) and can rotate (rotate around the first link contact point (101) as an axis), and the through hole formed at the opposite end thereof also overlaps with the fourth link contact point (202) of the lower member (200) and can rotate (rotate around the fourth link contact point (202) as an axis.

[0042] At this time, one end of the inner link member (310) is accommodated inside the lower end of the upper member (100), and the other end of the inner link member (310) is accommodated inside the upper end of the lower member (200).

[0043] Therefore, it is preferable to form a receiving groove in which the inner link member (310) can be received on the lower side of the upper member (100) and the upper side of the lower member (200).

[0044] In addition, it is preferable that the other side of the inner link member (310) is bent downward at a certain angle based on the length so as to be connected to the fourth link contact point (202) of the lower member (200).

[0045] Here, the inner link member (310) forms the first movable link (crank) among the four-section links as one end thereof overlaps with the first link contact point (101) of the upper member (100) and the other end thereof overlaps with the fourth link contact point (202) of the lower member (200).

[0046] In addition, it is preferable that the inner link member (310) is in a state where its lower surface contacts the upper surface of the lower member (200) when the knee is in an extended state.

[0047] And the outer link member (320) is provided as a pair of triangular pieces, and a pair of the outer link members (320) are provided on the lower left outer surface and the right outer surface of the upper member (100), respectively.

[0048] At this time, connecting points (321, 322, 323) are formed at the corners of the outer link members (320) forming a triangle, and the connecting points (321, 322, 323) are connected to the lower side of the upper member (100), the upper side of the lower member (200), and the traction member (430).

[0049] Here, it is preferable that the lower side of the outer link members (320) forming the base of the triangle is directed toward the lower member (200), and the upper corners of the outer link members (320) forming the upper side of the triangle are directed toward the upper member (100), and are connected to the lower side of the upper member (100), the upper side of the lower member (200), and the traction member (430).

[0050] And the first to third connecting points (321, 322, 323) of the outer link members (320) are also formed as through holes through which the shaft member passes, and the first connecting point (321) located at the upper end of the outer link members (320) overlaps with the second link contact point (102) of the upper member (100) and is rotatably connected to the shaft member, and the second connecting point (322) located at the front side overlaps with the third link contact point (201) of the lower member (200) and is rotatably connected to the shaft member.

[0051] At this time, the first connection point (321) of the outer link members (320) overlaps and is connected to the second link contact point (102) of the upper member (100), and the second connection point (322) of the outer link members (320) overlaps and is connected to the third link contact point (201) of the lower member (200), thereby forming the second movable link (crank) among the four-section links.

[0052] In addition, the first connection point (321) of the outer link members (320) overlaps and is connected to the second link contact point (102) of the upper member (100), and the second connection point (322) of the outer link members (320) overlaps and is connected to the third link contact point (201) of the lower member (200), so that the uppermost end of the lower member (200) where the fourth link contact point (202) is formed and the lowermost end of the upper member (100) where the first link contact point (101) is formed are in close contact with each other, thereby preventing the lower member (200) from rotating forward.

[0053] The third connection point (323) of the above outer link members (320) is rotatably connected to the left and right ends of the traction member (430).

[0054] At this time, the traction member (430) is in the shape of a '┴' with left and right ends and an upper end formed, and the left and right ends are rotatably connected to the third connection point (323) of the outer link members (320) between a pair of outer link members (320).

[0055] And the upper end of the above-mentioned traction member (430) is rotatably connected to the lower end of the ball screw (410).

[0056] Here, the ball screw (410) has a length in a vertical direction and is provided by being screw-connected to a nut member (420).

[0057] And the above nut member (420) is connected to the rotation axis of the driving motor (400) by a bevel gear.

[0058] The rotation axis of the above nut member (420) and the driving motor (400) are arranged orthogonally through a bevel gear, so that the driving motor (400) can be arranged on the side of the bevel gear, thereby having the advantage of miniaturizing the length of the robot leg.

[0059] When the rotation axis of the above driving motor (400) rotates in the horizontal direction, the nut member (420) connected to the bevel gear rotates in the vertical direction, causing the ball screw (410) to move upward or downward along the vertical direction, thereby causing the length of the ball screw (410) connected to the upper end of the traction member (430) to be expanded or contracted based on the nut member (420).

[0060] At this time, the above driving motor (400) is a disk-shaped BLDC motor, and the area is provided in a vertical line on the upper side of the upper member (100), so that the width of the robot leg can be configured to be relatively thin.

[0061] Additionally, the direction of movement of the ball screw (410) is determined according to the rotational direction of the nut member (420).

[0062] When the above driving motor (400) rotates and the nut member (420) rotates, the ball screw (410) can move upward according to the rotation of the nut member (420).

[0063] In this case, the ball screw (410) pulls the traction member (430) upward, and accordingly, the traction member (430) pulls the third connection point (323) of the outer link members (320) upward, so that a pair of the outer link members (320) simultaneously rotate clockwise about the first connection point (321) as an axis.

[0064] And as the outer link members (320) rotate clockwise around the first connection point (321) as an axis, the lower member (200) connected to the second connection point (322) rotates clockwise around the second connection point (322) as an axis, and also the inner link member (310) whose one end is rotatably overlapped with the first link contact point (101) of the upper member (100) rotates clockwise around the first link contact point (101) as an axis, thereby causing the knee to bend.

[0065] Here, the inner link member (310) rotates clockwise around the first link contact point (101) as an axis and when it comes into contact with the lower surface of the upper member (100), the rotation of the inner link member (310) is interrupted, but when a pulling force (further upward movement of the ball screw (410) occurs in this state), the lower member (200) rotates further around the fourth link contact point (202) that is connected to the other end of the inner link member (310) and overlaps with it.

[0066] Therefore, the structure of the robot leg according to the present invention can secure a wider operating range than a simple rotary joint structure through the above-described structure.

[0067] In addition, when the movement direction of the ball screw (410) is downward in the knee-bent state, the traction member (430) pushes the third connection point (323) of the outer link members (320), so that a pair of the outer link members (320) simultaneously rotate counterclockwise about the first connection point (321) as an axis.

[0068] And as the outer link members (320) rotate counterclockwise about the first connection point (321) as an axis, the lower member (200) connected to the second connection point (322) and the inner link member (310) whose one end is rotatably overlapped with the first link contact point (101) of the upper member (100) rotate counterclockwise about the second connection point (322) and the first link contact point (101) as an axis, thereby causing the knee to be extended.

[0069] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent alternative embodiments are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. Upper member forming the upper part above the knee of the robot leg; Lower member forming the lower part below the knee of the robot leg; A knee joint portion that rotatably connects the lower member to the lower end of the upper member; A driving motor provided on the upper member, optionally having a rotation axis that rotates in the forward or reverse direction; A nut member connected to the rotational axis of the above driving motor by a bevel gear and rotating in conjunction with the rotation of the rotational axis of the above driving motor; and A robot leg structure including a ball screw, the upper side being rotatably connected to the nut member about the length axis, the lower side being connected to the knee joint part, and moving upward or downward according to the rotational direction of the nut member, so that the lower side member connected to the knee joint part rotates clockwise or counterclockwise, thereby causing the knee of the robot leg to bend or extend.

2. In claim 1, The above upper member A first link contact is formed at the front edge of the lower part, and a second link contact is formed at the rear edge to form a first fixed link. The lower surface is a structure of a robot leg formed as an inclined surface so that the second link contact is positioned at a higher height phase than the first link contact.

3. In claim 2, The above lower part A third link contact is formed at the front edge of the upper part, and a fourth link contact is formed at the rear edge to form a second fixed link. The upper side is a structure of a robot leg formed as an inclined surface so that the fourth link contact is positioned at a position lower than the height phase of the third link contact.

4. In claim 3, The above knee joint An inner link member positioned between the lower end of the upper member and the upper end of the lower member, one end of which is rotatably connected to the lower front side of the upper member and the other end of which is rotatably connected to the upper rear side of the lower member; A robot leg structure including a pair of outer link members positioned on an outer surface between the lower end of the upper member and the upper end of the lower member and rotatably connecting the lower member with respect to the lower end of the upper member.

5. In claim 4, The above inner link member A robot leg structure in which a through hole formed on one side overlaps with a first link contact of the upper member and is rotatably connected, and a through hole formed on the other side overlaps with a fourth link contact of the lower member and is rotatably connected, and optionally forms a first movable link that rotates about the first link contact as an axis.

6. In claim 5, The above inner link member A robot leg structure in which the other side, which is overlapped with the fourth link contact point of the lower member, is bent toward the lower member based on the longitudinal direction.

7. In claim 4, The above outer link members A first coupling point is formed at one of the three corners to overlap and connect with the second link contact of the upper member, and a second coupling point is formed at the other corner to overlap and connect with the third link contact of the lower member, thereby forming a second movable link that selectively rotates about the first coupling point as an axis. A robot leg structure in which a third connection point is formed that is connected to the left and right ends of a traction member connected to the lower end of the ball screw at another corner.

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