Legs for a bipedal robot and bipedal robot

Abstract

The present invention provides a leg for a bipedal robot with a simple structure, enabling the bipedal robot to walk well on two legs. [Solution] The leg for the bipedal robot comprises a base portion 10, a knee portion 50, a foot portion 90, an upper leg portion 30, and a lower leg portion 70. The upper leg portion 30 has a first parallel link mechanism that moves the knee portion 50 relatively parallel to the upper surface of the base portion 10 in the front-rear direction, and a second parallel link mechanism that moves the knee portion 50 relatively parallel to the upper surface of the base portion 10 in the left-right direction. The lower leg portion 70 has a third parallel link mechanism that moves the foot portion 90 relatively parallel to the knee portion 50 in the direction of travel while keeping the lower surface of the foot portion 90 horizontal, and a fourth parallel link mechanism that moves the foot portion 90 relatively parallel to the knee portion 50 in the left-right direction while keeping the lower surface of the foot portion 90 horizontal.

Description

Technical Field

[0001] The present invention relates to a leg for a bipedal robot and a bipedal robot.

Background Art

[0002] Patent Document 1 discloses a conventional bipedal robot. The left and right legs of this bipedal robot include an upper leg portion that constitutes from the base portion connected to the body to the knee, and a lower leg portion that constitutes from the knee to the foot. The upper leg portion is constituted by a first parallel link mechanism that reciprocates the knee in the traveling direction with respect to the base portion. The lower leg portion is constituted by a second parallel link mechanism that reciprocates the foot in the traveling direction with respect to the knee. The left and right legs incorporate a mechanism for tilting the ankle in the left - right direction. When this bipedal robot performs a walking motion with the left and right legs reciprocating in the front - rear direction, it walks on two legs while maintaining the balance of the center of gravity by tilting the ankle in the left - right direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in order for the bipedal robot of Patent Document 1 to walk on two legs while maintaining the balance of the center of gravity, it is necessary to synchronize the reciprocating movement in the front - rear direction of each leg and the tilting angle in the left - right direction of the ankle, or to adjust the tilting angle of the ankle. Therefore, in order to make this bipedal robot walk well on two legs, these adjustments are laborious.

[0005] This invention has been made in view of the above-mentioned conventional circumstances, and aims to solve the problem of providing a bipedal robot capable of bipedal walking with a simple leg structure. [Means for solving the problem]

[0006] The leg portion for the bipedal robot of the present invention is When a bipedal robot is standing upright on a horizontal plane, The base portion, on which the torso is placed, has an upper surface parallel to the horizontal plane, The knee area, A foot portion whose lower surface is parallel to the horizontal plane, The upper leg portion comprising the part from the base to the knee, The lower leg portion comprising the knee portion to the foot portion, A leg for a bipedal robot, equipped with, The aforementioned upper leg portion is, A first parallel link mechanism moves the knee portion in parallel relative to the direction of travel with respect to the upper surface of the base portion, and in a side view taken from a direction perpendicular to the direction of travel, the upper leg portion reciprocates between a state in which it extends vertically from the base portion and a state in which it is inclined diagonally forward from the base portion. A second parallel link mechanism moves the knee portion in a direction perpendicular to the direction of travel relative to the upper surface of the base portion, causing the upper leg portion to reciprocate between a state in which it is tilted diagonally downward to the left from the base portion and a state in which it is tilted diagonally downward to the right from the base portion, in a front view taken from the front in the direction of travel. It has, The aforementioned lower leg portion is, A third parallel link mechanism that, while maintaining the lower surface of the foot horizontal, moves the foot in parallel relative to the knee in the direction of travel, causing the lower leg to reciprocate between a state in which it extends vertically from the knee and a state in which it is inclined diagonally backward from the knee, in a side view. A fourth parallel link mechanism that, while maintaining the lower surface of the foot horizontal, moves the foot in a direction perpendicular to the direction of travel relative to the knee, causing the lower leg to reciprocate between a state in which it is tilted diagonally downward to the left from the knee and a state in which it is tilted diagonally downward to the right from the knee. It has.

[0007] This bipedal robot leg has a second parallel link in the upper leg and a fourth parallel link in the lower leg. Therefore, while maintaining the horizontal position of the underside of the foot, it is possible to change the inclination of the upper and lower legs so that they are the same when viewed from the front, while relatively moving the knee relative to the upper surface of the hip joint in a direction perpendicular to the direction of movement, and moving the foot relative to the knee in a direction perpendicular to the direction of movement. In other words, this bipedal robot leg not only moves the foot in the direction of movement relative to the hip joint while maintaining the horizontal position of the underside of the foot, but also moves the foot from side to side relative to the hip joint when viewed from the front. For this reason, a bipedal robot equipped with a pair of these legs can easily shift its center of gravity to one leg and move the other leg in the direction of movement to walk on two legs effectively. Furthermore, because this bipedal robot leg has a simple structure, it can be miniaturized. Therefore, a bipedal robot equipped with a pair of these bipedal robot legs, one for each leg, can be made compact.

[0008] Therefore, the legs for the bipedal robot of the present invention have a simple structure, and a bipedal robot equipped with a pair of these legs as left and right legs can walk on two legs effectively. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view from the left front, showing the left and right legs and opening / closing drive unit of the bipedal robot of Example 1. [Figure 2] This is a perspective view of the left leg of Example 1, taken from the right rear. [Figure 3](1) to (8) are perspective views seen from the front left, showing the walking motions of the left and right legs step by step. [Figure 4] (1) to (8) are perspective views seen from the front right, showing the walking motions of the left and right legs step by step. [Figure 5] (1) to (8) are front views showing the walking motions of the left and right legs step by step. [Figure 6] (1) to (8) are left side views showing the walking motions of the left and right legs step by step. [Figure 7] (1) to (8) are right side views showing the walking motions of the left and right legs step by step. [Figure 8] (1) to (8) are perspective views seen from the front left, showing the motion of changing the traveling direction of the left and right legs step by step. [Figure 9] (1) to (8) are front views showing the motion of changing the traveling direction of the left and right legs step by step. [Figure 10] (1) to (8) are left side views showing the motion of changing the traveling direction of the left and right legs step by step. [Figure 11] (1) to (8) are right side views showing the motion of changing the traveling direction of the left and right legs step by step.

Best Mode for Carrying Out the Invention

[0010] Preferred embodiments of the present invention will be described.

[0011] The leg for a biped walking robot of the present invention may include a first drive unit for driving the first parallel link mechanism, a second drive unit for driving the third parallel link mechanism, and a third drive unit for driving the second parallel link mechanism and the fourth parallel link mechanism. In this case, a biped walking robot having a pair of legs for a biped walking robot as left and right legs can walk well by controlling the driving of the first drive unit to the third drive unit.

[0012] In the leg for a bipedal walking robot of the present invention, the first drive unit, the second drive unit, and the third drive unit may be provided at the knee. In this case, for the leg for a bipedal walking robot, by providing each drive unit at the knee, each parallel link can be directly driven with a simple structure, so that miniaturization can be achieved.

[0013] The bipedal walking robot of the present invention may include a pair of legs for a bipedal walking robot as left and right legs, and further may include an opening and closing drive unit that reciprocates between a state where the feet of each leg for a bipedal walking robot are parallel and a state where the front ends of the feet are open. In this case, for the leg for a bipedal walking robot, by means of an opening and closing mechanism, it reciprocates between a state where the left and right feet are arranged in parallel and a state where the front ends of the feet are open, and by each drive unit driving each parallel link mechanism, the direction of the bipedal walking robot can be changed.

[0014] The bipedal walking robot of the present invention may include a pair of legs for a bipedal walking robot as left and right legs. This bipedal walking robot can walk well on two legs. Also, since the left and right legs of this bipedal walking robot are configured with a simple structure, miniaturization can be achieved, and a small-sized robot can be realized.

[0015] Next, Example 1 in which a bipedal walking robot including a pair of legs for a bipedal walking robot of the present invention as left and right legs is embodied will be described while referring to the drawings.

[0016] <Example 1> As shown in FIG. 1, the bipedal walking robot of Example 1 includes a pair of left and right legs 1L and 1R. Each of the left and right legs 1L and 1R corresponds to the leg for a bipedal walking robot. Each of the left and right legs 1L and 1R includes a base portion 10, an upper leg portion 30, a knee portion 50, a lower leg portion 70, a foot portion 90, and first to third motors M1 to M3. The left and right legs 1L and 1R include an opening and closing mechanism 20. The bipedal walking robot mounts a body portion (not shown) on the upper surface of the base portions 10 of the pair of left and right legs 1L and 1R. The body portion is provided with a head (not shown) and left and right arm portions.

[0017] For the sake of explanation, the direction of movement of a bipedal robot is defined as forward, and the opposite direction as backward. The left-right direction is defined as the direction from the perspective of a bipedal robot facing the direction of movement. The up-down direction is defined as the direction of movement of a bipedal robot when it is standing upright on a horizontal plane. In the three-dimensional Cartesian coordinate system shown in Figures 1 and 2, the positive direction of the X axis is "forward," and the negative direction is "backward," the positive direction of the Y axis is "right," and the negative direction is "left," and the positive direction of the Z axis is "up," and the negative direction is "down."

[0018] <Regarding the left and right leg sections 1L and 1R> The left leg 1L of the bipedal robot is described below. The right leg 1R has the same configuration as the left leg 1L, but its components are arranged symmetrically to those of the left leg 1L. In each figure, the symbols assigned to the components of the right leg 1R are the same as the symbols assigned to the corresponding components of the left leg 1L.

[0019] As shown in Figures 1 and 2, the upper surface of the base portion 10 is parallel to the horizontal plane when the bipedal robot is standing upright on a horizontal plane. In a plan view of the bipedal robot from above (hereinafter referred to as "plan view"), the base portion 10 is a roughly flat, square-shaped plate with opposite sides extending in the front-to-back direction. The base portion 10 has a left convex portion 11L and a right convex portion 11R projecting downward from the left and right ends of the central part of the opposite sides extending in the front-to-back direction. Each convex portion 11L, 11R forms a through hole (not shown) that penetrates in the front-to-back direction. The cross-sectional shape perpendicular to the central axis of this through hole is circular.

[0020] As shown in Figures 1 and 2, the upper leg portion 30 has a left upper joint portion 31L, a right upper joint portion 31R, and three upper connecting portions 33. Each upper joint portion 31L, 31R is the same shape. The length of each upper joint portion 31L, 31R in the front-to-back direction is the same as the length of the base portion 10 in the front-to-back direction. The upper surface of each upper joint portion 31L, 31R bulges upward in a semi-circular shape when viewed from the front of the bipedal walking robot (hereinafter referred to as "front view"). The upper part of each upper joint portion 31L, 31R forms a front-to-back through hole 35 that penetrates in the front-to-back direction. The cross-sectional shape perpendicular to the central axis of this front-to-back through hole 35 is circular. The upper part of each upper joint portion 31L, 31R forms a notch 37 in the center in the front-to-back direction into which the convex portion of the base portion 10 fits.

[0021] The upper left joint 31L is attached to the base 10 with the left convex portion 11L of the base 10 fitted into the upper notch 37, and a cylindrical shaft member 39 is inserted into the front and rear through holes 35 formed on the upper part of the upper left joint 31L, as well as the through hole formed in the left convex portion 11L. The upper right joint 31R is attached to the base 10 with the right convex portion 11R of the base 10 fitted into the upper notch 37, and a cylindrical shaft member 39 is inserted into the front and rear through holes 35 formed on the upper part of the upper right joint 31R, as well as the through hole formed in the right convex portion 11R. Each upper joint 31L, 31R is attached to the base 10 so as to be able to swing left and right around the shaft member 39 inserted into the front and rear through holes 35 formed on the upper part.

[0022] Each upper joint portion 31L, 31R has a left wall portion 41L and a right wall portion 41R extending downward from the upper left and right edges. The left wall portion 41L and the right wall portion 41R are rectangular flat plates that are long in the front-to-back direction. The left wall portion 41L and the right wall portion 41R are identical in shape. The left wall portion 41L and the right wall portion 41R are arranged parallel to each other with their back surfaces facing each other and spaced apart to the left and right. The distance between the left wall portion 41L and the right wall portion 41R is slightly wider than the thickness (width) of the upper connecting portion 33.

[0023] The left wall portion 41L and the right wall portion 41R of each upper joint portion 31L and 31R have through holes 43 formed in the left-right direction (thickness direction) at their front and rear ends, respectively. The cross-sectional shape perpendicular to the central axis of these through holes 43 is circular. The central axes of the front left-right through holes 43 of the left wall portion 41L and the right wall portion 41R are located on the same straight line, and the central axes of the rear left-right through holes 43 are located on the same straight line.

[0024] Each upper connecting portion 33 is a flat plate that is elongated in the vertical direction. Each upper connecting portion 33 has through holes (not shown) that penetrate in the thickness direction at its upper and lower ends. The cross-sectional shape perpendicular to the central axis of each through hole is circular.

[0025] One of the three upper connecting parts 33 is connected to the left upper joint part 31L. The upper end of this upper connecting part 33 is inserted between the left wall part 41L and the right wall part 41R of the left upper joint part 31L, and a cylindrical shaft member 45 is inserted into a through hole formed at the upper end, along with the left and right through holes 43 formed at the rear ends of the left wall part 41L and the right wall part 41R of the left upper joint part 31L. This upper connecting part 33 extends downward from the rear end of the left upper joint part 31L and is swingable in the front-rear direction around the shaft member 45 inserted into the through hole formed at the upper end.

[0026] The remaining two of the three upper connecting parts 33 are connected to the upper right joint part 31R, as shown in Figure 2. One of the upper connecting parts 33 connected to the upper right joint part 31R has its upper end inserted between the left wall part 41L and the right wall part 41R of the upper right joint part 31R, and a cylindrical shaft member 45 is inserted into the through hole formed at its upper end, along with the left and right through holes 43 formed at the front ends of the left wall part 41L and the right wall part 41R of the upper right joint part 31R. The other upper connecting part 33 connected to the upper right joint part 31R has its upper end inserted between the left wall part 41L and the right wall part 41R of the upper right joint part 31R, and a cylindrical shaft member 45 is inserted into the through hole formed at its upper end, along with the left and right through holes 43 formed at the rear ends of the left wall part 41L and the right wall part 41R of the upper right joint part 31R. These two upper connecting portions 33 extend downward from the front and rear ends of the upper right joint portion 31R, and are freely pivotable in the front-rear direction around the shaft member 45 inserted into the through holes formed in the upper ends of each portion.

[0027] As shown in Figures 1 and 2, the knee portion 50 has a left knee joint portion 51, a right knee joint portion 52, a front connecting portion 53, and a rear connecting portion 54. Each knee joint portion 51, 52 has a left wall portion 55L, a right wall portion 55R, a front wall portion 55F, and a rear wall portion 55B. The left wall portion 55L and the right wall portion 55R are rectangular flat plates that are long in the front-rear direction. The left wall portion 55L and the right wall portion 55R are identical in shape. The left wall portion 55L and the right wall portion 55R are arranged parallel to each other with their back surfaces facing each other and separated to the left and right. The distance between the left wall portion 55L and the right wall portion 55R is slightly wider than the thickness (width from left to right) of the upper connecting portion 33. The front ends of the left wall portion 55L and the right wall portion 55R are connected by the front wall portion 55F. The rear ends of the left wall portion 55L and the right wall portion 55R are connected by the rear wall portion 55B.

[0028] The left wall portion 55L and the right wall portion 55R of each knee joint portion 51, 52 have left and right through holes 57 formed at positions separated in the front-rear direction, respectively, that penetrate in the left-right direction (thickness direction). The cross-sectional shape perpendicular to the central axis of these left and right through holes 57 is circular. The central axes of the left and right through holes 57 on the front side of the left wall portion 55L and the right wall portion 55R are located on the same straight line, and the central axes of the left and right through holes 57 on the rear side are also located on the same straight line. The distance between the central axes of the left and right through holes 57 formed on the front side of the left wall portion 55L and the right wall portion 55R and the central axes of the left and right through holes 57 formed on the rear side is equal to the distance between the central axes of the left and right through holes 43 formed at the front end of the left wall portion 41L and the right wall portion 41R of each upper joint portion 31L, 31R and the central axes of the left and right through holes 43 formed at the rear end.

[0029] The left knee joint portion 51 has an upper connecting portion 33 connected to the left upper joint portion 31L and the upper end of a lower connecting portion 71 of the lower leg portion 70 (described later) inserted between the left wall portion 55L and the right wall portion 55R. The left knee joint portion 51 has a cylindrical first drive shaft member 61 inserted into left and right through holes 57 formed on the rear sides of the left wall portion 55L and the right wall portion 55R, along with a through hole formed at the lower end of the upper connecting portion 33 inserted between the left wall portion 55L and the right wall portion 55R. The first drive shaft member 61 is connected to a through hole formed at the lower end of the upper connecting portion 33. The first drive shaft member 61 is rotatable with respect to the left and right through holes 57 formed on the rear sides of the left wall portion 55L and the right wall portion 55R of the left knee joint portion 51.

[0030] The upper connecting portion 33, which is connected to the first drive shaft member 61, swings in the front-to-back direction around the first drive shaft member 61 as the first drive shaft member 61 rotates. More specifically, in a left-side view of the bipedal robot (hereinafter referred to as "left-side view"), the upper connecting portion 33, which is connected to the first drive shaft member 61 and extends in the vertical direction, changes to a state where it is tilted diagonally forward from the upper end to the lower end when the first drive shaft member 61 is rotated clockwise. In other words, the knee portion 50 moves upward so that it is in front of the base portion 10.

[0031] In a left side view, the upper connecting portion 33, which is connected to the first drive shaft member 61 and is inclined diagonally forward from its upper end to its lower end, changes to an extended state in the vertical direction when the first drive shaft member 61 is rotated counterclockwise. In other words, the knee portion 50 moves below the base portion 10.

[0032] As shown in Figure 2, the right knee joint portion 52 is inserted between the left wall portion 55L and the right wall portion 55R, with the lower ends of two upper connecting portions 33 connected to the right upper joint portion 31R and the upper ends of two lower connecting portions 71 of the lower leg portion 70, which will be described later, overlapping. The right knee joint portion 52 inserts a cylindrical shaft member 59 into left and right through holes 57 formed on the front side of the left wall portion 55L and the right wall portion 55R, along with a through hole formed in the lower end of an upper connecting portion 33 extending downward from the front end of the right upper joint portion 31R and a through hole formed in the upper end of one of the lower connecting portions 71. The right knee joint portion 52 inserts a cylindrical shaft member 59 into left and right through holes 57 formed on the rear side of the left wall portion 55L and the right wall portion 55R, along with a through hole formed in the lower end of an upper connecting portion 33 extending downward from the rear end of the right upper joint portion 31R and a through hole formed in the upper end of the other lower connecting portion 71. These two upper connecting portions 33 are pivotable in the front-rear direction around a shaft member 59 inserted into a through hole formed at their lower end relative to the right knee joint portion 52. These two lower connecting portions 71 are pivotable in the front-rear direction around a shaft member 59 inserted into a through hole formed at their upper end.

[0033] As shown in Figures 1 and 2, the front connecting portion 53 and the rear connecting portion 54 are rectangular flat plates that are elongated in the left-right direction. The front connecting portion 53 and the rear connecting portion 54 are connected by a cylindrical central connecting portion 65 that extends from the left-right center of the rear surface of the front connecting portion 53 to the left-right center of the front surface of the rear connecting portion 54. The central connecting portion 65 is positioned between the left knee joint portion 51 and the right knee joint portion 52. The front connecting portion 53 and the rear connecting portion 54 have through holes 66 that penetrate in the thickness direction at both the left and right ends. The cross-sectional shape perpendicular to the central axis of each through hole 66 is circular. The distance between the central axes of the through holes 66 formed at both the left and right ends of the front connecting portion 53 and the rear connecting portion 54 is equal to the distance between the central axis of the front-rear through hole 35 formed in the left upper joint portion 31L and the central axis of the front-rear through hole 35 formed in the right upper joint portion 31R.

[0034] The through-hole 66 on the left side of the front connecting portion 53 is into which a third drive shaft member 63, which is connected to the front wall portion 55F of the left knee joint portion 51, is inserted. The third drive shaft member 63 is rotatable relative to the through-hole 66 on the left side of the front connecting portion 53. The through-hole 66 on the right side of the front connecting portion 53 is into which a shaft member 67, which is connected to the front wall portion 55F of the right knee joint portion 52, is inserted. This shaft member 67 is rotatable relative to the through-hole 66 on the right side of the front connecting portion 53. The left knee joint portion 51, which is connected to the third drive shaft member 63, swings from side to side around the third drive shaft member 63 due to the rotation of the third drive shaft member 63.

[0035] The through-hole 66 on the left side of the rear connecting portion 54 is into which a shaft member 67 connected to the rear wall portion 55B of the left knee joint portion 51 is inserted. This shaft member 67 is rotatable relative to the through-hole 66 on the left side of the rear connecting portion 54. The through-hole 66 on the right side of the rear connecting portion 54 is into which a shaft member 67 connected to the rear wall portion 55B of the right knee joint portion 52 is inserted. This shaft member 67 is rotatable relative to the through-hole 66 on the right side of the rear connecting portion 54.

[0036] As shown in Figures 1 and 2, the lower leg portion 70 has three lower connecting portions 71, a left lower joint portion 73L, and a right lower joint portion 73R. Each lower connecting portion 71 has the same shape as the upper connecting portion 33. One of the three lower connecting portions 71 is connected to the left knee joint portion 51. The upper end of this lower connecting portion 71 is inserted between the left wall portion 55L and the right wall portion 55R of the left knee joint portion 51, and the second drive shaft member 62 is inserted into a through hole formed at the upper end, along with the left and right through holes 57 formed on the front sides of the left wall portion 55L and the right wall portion 55R of the left knee joint portion 51. The second drive shaft member 62 is connected to a through hole formed at the upper end of the lower connecting portion 71. The second drive shaft member 62 is rotatable with respect to the left and right through holes 57 formed on the front sides of the left wall portion 55L and the right wall portion 55R of the left knee joint portion 51.

[0037] The lower connecting portion 71, which is connected to the second drive shaft member 62, swings in the front-to-back direction around the second drive shaft member 62 as the second drive shaft member 62 rotates. Specifically, in a left side view of the bipedal robot, the lower connecting portion 71, which is connected to the second drive shaft member 62 and extends in the vertical direction, changes to a state where it is tilted diagonally backward from the upper end to the lower end when the second drive shaft member 62 is rotated counterclockwise. In other words, the foot portion 90 moves upward so as to approach the rear side of the knee portion 50.

[0038] In a left side view, the lower connecting portion 71, which is connected to the second drive shaft member 62 and is inclined diagonally backward from its upper end to its lower end, changes to an extended state in the vertical direction when the second drive shaft member 62 is rotated clockwise. In other words, the foot portion 90 moves below the knee portion 50.

[0039] The remaining two of the three lower connecting parts 71 are connected to the right knee joint 52, as shown in Figure 2. One of the lower connecting parts 71 connected to the right knee joint 52 has its upper end inserted between the left wall 55L and the right wall 55R of the right knee joint 52, and a cylindrical shaft member 59 is inserted into a through hole formed at its upper end, along with left and right through holes 57 formed on the front side of the left wall 55L and the right wall 55R of the right knee joint 52. The other lower connecting part 71 connected to the right knee joint 52 has its upper end inserted between the left wall 55L and the right wall 55R of the right knee joint 52, and a cylindrical shaft member 59 is inserted into a through hole formed at its upper end, along with left and right through holes 57 formed on the rear side of the left wall 55L and the right wall 55R of the right knee joint 52. These two lower connecting portions 71 extend downward from positions separated in the front-rear direction of the right knee joint portion 52, and are freely pivotable in the front-rear direction around a shaft member 59 inserted into a through hole formed at the upper end of each.

[0040] Each lower joint portion 73L, 73R has the same shape as each upper joint portion 31L, 31R, and is attached to the left and right ends of the foot portion 90, respectively, inverted vertically. The left lower joint portion 73L is inserted between the left wall portion 74L and the right wall portion 74R by inserting a single lower connecting portion 71 connected to the left knee joint portion 51. A cylindrical shaft member 76 is inserted into the left and right through holes 75 formed at the front ends of the left wall portion 74L and the right wall portion 74R, along with a through hole formed at the lower end of the lower connecting portion 71 inserted between the left wall portion 74L and the right wall portion 74R. This lower connecting portion 71 is swingable in the front-rear direction relative to the left lower joint portion 73L, around the shaft member 76 inserted into the through hole formed at its lower end.

[0041] As shown in Figure 2, the right lower joint portion 73R has the lower ends of two lower connecting portions 71 connected to the right knee joint portion 52 inserted between the left wall portion 74L and the right wall portion 74R. The right lower joint portion 73R has a cylindrical shaft member 76 inserted into left and right through holes 75 formed at the front ends of the left wall portion 74L and the right wall portion 74R, along with a through hole formed at the lower end of the front lower connecting portion 71 that extends downward from the right knee joint portion 52. The right lower joint portion 73R also has a cylindrical shaft member 76 inserted into left and right through holes 75 formed at the front ends of the left wall portion 74L and the right wall portion 74R, along with a through hole formed at the lower end of the rear lower connecting portion 71 that extends downward from the right knee joint portion 52. These two lower connecting portions 71 are swingable in the front-rear direction relative to the right lower joint portion 73R around the shaft member 76 inserted into the through holes formed at their lower ends.

[0042] The foot portion 90 is a roughly flat rectangular plate with opposite sides extending in the front-to-back direction in a plan view. The width of the foot portion 90 is equal to the width of the base portion 10. The length of the foot portion 90 in the front-to-back direction is longer than the length of the base portion 10 in the front-to-back direction. The lower surface of the foot portion 90 is parallel to and in contact with the horizontal plane when the bipedal robot is standing upright on a horizontal plane. The foot portion 90 has a left convex portion 91L and a right convex portion 91R projecting upward from the left and right ends at the center of the opposite sides extending in the front-to-back direction. Each convex portion 91L, 91R forms a through hole (not shown) that penetrates in the front-to-back direction. The cross-sectional shape perpendicular to the central axis of this through hole is circular.

[0043] The foot portion 90 has its left convex portion 91L fitted into the notch 77 at the bottom of the left lower joint portion 73L, and the shaft member 79 is inserted into the through hole formed in the left convex portion 91L along with the front and rear through hole 78 formed at the bottom of the left lower joint portion 73L. The foot portion 90 has its right convex portion 91R fitted into the notch 77 at the bottom of the right lower joint portion 73R, and the shaft member 79 is inserted into the through hole formed in the right convex portion 91R along with the front and rear through hole 78 formed at the bottom of the right lower joint portion 73R. Each lower joint portion 73L, 73R is attached to the foot portion 90 so as to be able to swing from side to side around the shaft member 79 inserted into the front and rear through hole 78 formed at the bottom.

[0044] The first motor M1 to the third motor M3 are located in the left knee joint 51 of the knee portion 50. The first motor M1 to the third motor M3 correspond to the first drive unit to the third drive unit. The first motor M1 to the third motor M3 are DC motors. The first motor M1 has its rotating shaft connected to the first drive shaft member 61 and is attached to the left wall portion 55L of the left knee joint 51 of the left knee portion 50. The second motor M2 has its rotating shaft connected to the second drive shaft member 62 and is attached to the left wall portion 55L of the left knee joint 51 of the left knee portion 50. The third motor M3 has its rotating shaft connected to the third drive shaft member 63 and is attached to the front connecting portion 53 of the left knee portion 50.

[0045] The two upper connecting parts 33 connected between the upper right joint 31R and the right knee joint 52 change their inclination angle in the front-rear direction in synchronization with the upper connecting parts 33 connected to the first drive shaft member 61, which is rotated by the first motor M1. In other words, in a side view from either the left or right direction (hereinafter referred to as "side view"), when the first drive shaft member 61 is rotated by the first motor M1, and the upper connecting parts 33 connected to the first drive shaft member 61 are changed between a state where they are extended vertically and a state where they are inclined diagonally forward from the upper end to the lower end, the two upper connecting parts 33 connected between the upper right joint 31R and the right knee joint 52 also change between a state where they are extended vertically and a state where they are inclined diagonally forward from the upper end to the lower end in a side view, in accordance with this change. More specifically, the three upper connecting parts 33 that make up the upper leg part 30 move synchronously back and forth between a state in which they extend vertically from the base part 10 and a state in which they are tilted diagonally forward from the base part 10, as seen from the side.

[0046] The right upper joint portion 31R, the two upper connecting portions 33 extending downward from the front and rear ends of the right upper joint portion 31R, and the right knee joint portion 52 connecting the lower ends of these two upper connecting portions 33 constitute a first parallel link mechanism. Therefore, the knee portion 50 can be moved in parallel in the front-rear direction relative to the upper surface of the base portion 10 which is parallel to the horizontal plane. The first parallel link mechanism is driven by the first motor M1.

[0047] The two lower connecting parts 71 connected between the right knee joint 52 and the right lower joint 73R change their inclination angle in the front-rear direction in synchronization with the lower connecting parts 71 connected to the second drive shaft member 62, which is rotated by the second motor M2. In other words, in a side view, when the second drive shaft member 62 is rotated by the second motor M2, and the lower connecting parts 71 connected to the second drive shaft member 62 are changed between a state where they are extended vertically and a state where they are inclined diagonally backward from the upper end to the lower end, the two lower connecting parts 71 connected between the right knee joint 52 and the right lower joint 73R also change in a side view between a state where they are extended vertically and a state where they are inclined diagonally backward from the upper end to the lower end. Specifically, the three lower connecting parts 71 constituting the lower leg 70 move back and forth in synchronization in a side view between a state where they are extended vertically from the knee 50 and a state where they are inclined diagonally backward from the knee 50.

[0048] The right knee joint 52, two lower connecting parts 71 extending downward from the right knee joint 52 in the anterior-posterior direction, and the right lower joint 73R connecting the lower ends of these two lower connecting parts 71 constitute a third parallel link mechanism. As a result, the foot 90 can be moved in parallel relative to the knee 50 in the anterior-posterior direction. In this case, the bottom surface of the foot 90 moves parallel to the horizontal plane in a side view. The third parallel link mechanism is driven by the second motor M2.

[0049] Each upper connecting portion 33 and each lower connecting portion 71 changes its tilt angle in the left-right direction in synchronization with the left-right rotation of the left knee joint portion 51 connected to the third drive shaft member 63, which is rotated by the third motor M3. In other words, when the third drive shaft member 63 is rotated by the third motor M3, and the left knee joint portion 51 connected to the third drive shaft member 63 is rotated left or right, each upper connecting portion 33 and each lower connecting portion 71 changes between a state inclined diagonally downward to the left from the upper end and a state inclined diagonally downward to the right from the upper end. Specifically, the three upper connecting portions 33 constituting the upper leg portion 30 move back and forth in synchronization between a state inclined diagonally downward to the left from the base portion 10 and a state inclined diagonally downward to the right from the base portion 10 when viewed from the front. Furthermore, the three lower connecting parts 71 that make up the lower leg portion 70 move synchronously back and forth between a state inclined diagonally downward to the left from the knee portion 50 and a state inclined diagonally downward to the right from the knee portion 50 when viewed from the front.

[0050] The base portion 10, each upper joint portion 31L, 31R, each upper connecting portion 33, and the knee portion 50 constitute a second parallel link mechanism. The knee portion 50, each lower connecting portion 71, each lower joint portion 73L, 73R, and the foot portion 90 constitute a fourth parallel link mechanism. As a result, the knee portion 50 can be moved in a parallel direction relative to the upper surface of the base portion 10 in the left-right direction, and the foot portion 90 can be moved in a parallel direction relative to the knee portion 50 in the left-right direction. In this case, the bottom surface of the foot portion 90 moves parallel to the horizontal plane when viewed from the front. The second and fourth parallel link mechanisms are driven by the third motor M3.

[0051] <About the opening / closing mechanism 20> The opening / closing mechanism 20 is located on the upper side of the left and right legs 1L and 1R, as shown in Figure 1. The opening / closing mechanism 20 has one worm gear 21 and two worm wheels 23. The rotational center hole of each worm wheel 23 is connected by inserting a shaft portion 13 that extends from the center of the upper surface of the respective base portions 10 of the left and right legs 1L and 1R. The worm gear 21 is positioned between the worm wheels 23. The worm gear 21 rotates in both directions by a DC motor (not shown).

[0052] When the left and right foot portions 90 of the left and right legs 1L and 1R are positioned parallel to each other, and one leg is raised from the horizontal plane and the worm gear 21 is rotated in one direction, one leg rotates with the worm wheel 23 relative to the other leg, and the front end of the foot portion 90 of one leg opens relative to the front end of the foot portion 90 of the other leg. When the worm gear 21 is rotated in the opposite direction from this state, one leg rotates in the opposite direction with the worm wheel 23 relative to the other leg, and the left and right foot portions 90 are positioned parallel to each other, and the front ends of the left and right foot portions 90 close together.

[0053] <About bipedal locomotion> Figures 3 to 7 show the walking motion in stages, in the order of (1) to (8). In each of Figures 3 to 7, (1) shows the initial state. In this initial state, the upper leg portions 30 of the left and right legs 1L and 1R extend vertically from the hip joint 10 in a lateral view, and the lower leg portions 70 extend vertically from the knee joint 50 in a lateral view. In a frontal view, the left leg portion 1L is tilted diagonally downward to the left from the hip joint 10, and the right leg portion 1R is tilted diagonally downward to the right from the hip joint 10.

[0054] In Figures 3 to 7, (2) shows the first stage, in which the left foot 90 is brought closer to the right foot 90 and the left foot 90 is used as the center of gravity while standing. To change the left and right legs 1L and 1R to the first stage, the third motor M3 of the left leg 1L is driven, and the third drive shaft member 63 is rotated clockwise in a front view. As a result, in a front view, the upper leg portion 30 of the left leg 1L is tilted diagonally downward to the right from the base portion 10, and the lower leg portion 70 of the left leg 1L is tilted diagonally downward to the right from the knee portion 50. In this way, the left and right legs 1L and 1R change to the first stage, in which the left foot 90 is brought closer to the right foot 90 and the left foot 90 is used as the center of gravity while standing.

[0055] In Figures 3 to 7, (3) shows the second stage, in which the right leg 1R is bent and the right foot 90 is raised. To change the left and right legs 1L and 1R to the second stage, the first motor M1 and second motor M2 of the right leg 1R are driven to rotate the first drive shaft member 61 counterclockwise and the second drive shaft member 62 clockwise in a right side view. As a result, in a right side view, the upper leg portion 30 of the right leg 1R is tilted diagonally forward from the base portion 10, and the lower leg portion 70 is tilted diagonally backward from the knee portion 50. In this way, the left and right legs 1L and 1R change to the second stage, in which the right leg 1R is bent and the right foot is raised.

[0056] In Figures 3 to 7, (4) shows the third stage with the right foot extended forward. To change the left and right legs 1L and 1R to the third stage, the second motor M2 of the right leg 1R is driven to rotate the second drive shaft member 62 counterclockwise in a right side view. As a result, in a right side view, the lower leg portion 70 of the right leg 1R extends vertically from the knee portion 50. In this way, the left and right legs 1L and 1R change to the third stage with the right foot extended forward.

[0057] In Figures 3 to 7, (5) shows the fourth stage, in which the left leg 1L is bent and the right foot 90 is on the ground. To change the left and right legs 1L and 1R to the fourth stage, the second motor M2 of the left leg 1L is driven to rotate the second drive shaft member 62 counterclockwise in a left side view. As a result, in a left side view, the lower leg portion 70 of the left leg 1L is tilted diagonally backward from the knee portion 50. In this way, the left and right legs 1L and 1R change to the fourth stage, in which the left leg 1L is bent and the right foot 90 is on the ground.

[0058] In Figures 3 to 7, (6) indicates the fifth stage with the right foot 90 as the center of gravity. To change the left and right legs 1L and 1R to the fifth stage, the third motor M3 of the left leg 1L and the third motor M3 of the right leg 1R are driven, and in a front view, the third drive shaft members 63 of the left leg 1L and the right leg 1R are rotated counterclockwise. As a result, in a front view, the upper leg portion 30 of the left and right legs 1L and 1R is tilted diagonally downward to the left from the base portion 10, and the lower leg portion 70 of the left and right legs 1L and 1R is tilted diagonally downward to the left from the knee portion 50. In this way, the left and right legs 1L and 1R change to the fifth stage with the right foot 90 as the center of gravity.

[0059] In Figures 3 to 7, (7) indicates the sixth stage, in which the right leg 1R is extended and the left foot 90 is raised. To change the left and right legs 1L and 1R to the sixth stage, the first motor M1 of the right leg 1R is driven to rotate the first drive shaft member 61 clockwise in a right side view. As a result, in a right side view, the upper leg portion 30 of the right leg 1R extends vertically from the base portion 10. In this way, the left and right legs 1L and 1R change to the sixth stage, in which the right leg 1R is extended and the left foot 90 is raised.

[0060] (8) in Figures 3 to 7 shows the seventh stage, where the left leg 1L is extended and the left foot 90 is placed on the ground. To change the left and right legs 1L and 1R to the seventh stage, the second motor M2 of the left leg 1L is driven to rotate the second drive shaft member 62 clockwise in the left side view. As a result, in the left side view, the lower leg portion 70 of the left leg 1L extends vertically from the knee portion 50. In this way, the left and right legs 1L and 1R change to the seventh stage, where the left leg 1L is extended and the left foot 90 is placed on the ground. (1) to (8) in Figures 3 to 7 show the movement from taking a step with the right foot 90 to bringing the left foot 90 to match the right foot 90, but similarly, the left and right feet 90 can be moved continuously to enable bipedal walking.

[0061] <Regarding the operation of changing orientation> Figures 8 to 11 show the directional change operation in stages, from (1) to (8). In each of Figures 8 to 11, (1) shows the initial state. In this initial state, the upper leg portion 30 of the left and right legs 1L and 1R extends vertically from the base portion 10 in a side view, and the lower leg portion 70 extends vertically from the knee portion 50 in a side view. Also, in a front view, the left and right legs 1L and 1R are inclined diagonally downward to the right from the base portion 10. In the initial state, the left and right legs 1L and 1R are standing with the left foot portion 90 as the center of gravity.

[0062] In Figures 8 to 11, (2) indicates the first stage in which the right leg 1R is bent and the right foot 90 is raised. To change the left and right legs 1L and 1R to the first stage, the first motor M1 and second motor M2 of the right leg 1R are driven to rotate the first drive shaft member 61 counterclockwise and the second drive shaft member 62 clockwise in a right side view. As a result, in a right side view, the upper leg portion 30 of the right leg 1R is tilted diagonally forward from the base portion 10, and the lower leg portion 70 is tilted diagonally backward from the knee portion 50. In this way, the left and right legs 1L and 1R change to the first stage in which the right leg 1R is bent and the right foot 90 is raised.

[0063] In Figures 8 to 11, (3) shows the second stage, in which the right leg 1R is rotated clockwise, causing the front end of the right foot 90 to open relative to the front end of the left foot 90. To change the left and right legs 1L and 1R to the second stage, the worm gear 21 is rotated counterclockwise in a front view, and the worm wheel 23, located on the upper surface of the base 10 of the right leg 1R, is rotated clockwise in a plan view. As a result, the right leg 1R rotates clockwise together with the worm wheel 23, changing to the second stage, in which the front end of the right foot 90 opens relative to the front end of the left foot 90.

[0064] In Figures 8 to 11, (4) shows the third stage, in which the right leg 1R is extended and the right foot 90 is on the ground. To change the left and right legs 1L and 1R to the third stage, the first motor M1 and second motor M2 of the right leg 1R are driven to rotate the first drive shaft member 61 clockwise and the second drive shaft member 62 counterclockwise in a right side view. As a result, in a right side view, the upper leg portion 30 of the right leg 1R extends vertically from the base portion 10, and the lower leg portion 70 extends vertically from the knee portion 50. In this way, the left and right legs 1L and 1R change to the third stage, in which the right leg 1R is extended and the right leg 1R is on the ground.

[0065] (5) in each of Figures 8 to 11 shows the fourth stage with the right foot 90 as the center of gravity. To change the left and right legs 1L and 1R to the fourth stage, the third motor M3 of the left leg 1L and the third motor M3 of the right leg 1R are driven, and in a front view, the third drive shaft members 63 of the left leg 1L and the right leg 1R are rotated counterclockwise. As a result, in a front view, the upper leg portion 30 of the left and right legs 1L and 1R is tilted diagonally downward to the left from the base portion 10, and the lower leg portion 70 of the left and right legs 1L and 1R is tilted diagonally downward to the left from the knee portion 50. In this way, the left and right legs 1L and 1R change to the fifth stage with the right foot 90 as the center of gravity.

[0066] In Figures 8 to 11, (6) shows the fourth stage, in which the left leg 1L is bent and the left foot 90 is raised. To change the left and right legs 1L and 1R to the fourth stage, the first motor M1 and second motor M2 of the left leg 1L are driven to rotate the first drive shaft member 61 clockwise and the second drive shaft member 62 counterclockwise in a left side view. As a result, in a left side view, the upper leg portion 30 of the left leg 1L is tilted diagonally forward from the base portion 10, and the lower leg portion 70 is tilted diagonally backward from the knee portion 50. In this way, the left and right legs 1L and 1R change to the fourth stage, in which the left leg 1L is bent and the left foot 90 is raised.

[0067] In Figures 8 to 11, (7) shows the fifth stage, in which the left leg 1L is rotated clockwise so that the left foot 90 is positioned parallel to the right foot 90 and the front end of the left foot 90 is closed relative to the front end of the right foot 90. To change the left and right legs 1L and 1R to the fifth stage, the worm gear 21 is rotated clockwise in a front view, and the worm wheel 23, which is provided on the upper surface of the base 10 of the left leg 1L, is rotated clockwise in a plan view. As a result, the left leg 1L rotates clockwise together with the worm wheel 23, and the left foot 90 is positioned parallel to the right leg 1R, and the front end of the left foot 90 is closed relative to the front end of the right foot 90, resulting in the fifth stage.

[0068] In Figures 8 to 11, (8) indicates the seventh stage, in which the left leg 1L is extended and the left foot 90 is on the ground. To change the left and right legs 1L and 1R to the seventh stage, the first motor M1 and second motor M2 of the left leg 1L are driven to rotate the first drive shaft member 61 counterclockwise and the second drive shaft member 62 clockwise in a left side view. As a result, in a left side view, the upper leg portion 30 of the left leg 1L extends vertically from the base portion 10, and the lower leg portion 70 extends vertically from the knee portion 50. In this way, the left and right legs 1L and 1R change to the seventh stage, in which the left leg 1L is extended and the left foot 90 is on the ground. Figures 8 to 11, (1) to (8), show the movement of changing the orientation of the left and right legs 1L and 1R diagonally to the right in a plan view. Similarly, the orientation of the left and right legs 1L and 1R can be changed diagonally to the left in a plan view.

[0069] As described above, the left and right legs 1L and 1R of Embodiment 1 include a base portion 10 on which the torso rests when the bipedal robot is standing upright on a horizontal plane, a knee portion 50, a foot portion 90 on which the lower surface is parallel to the horizontal plane, an upper leg portion 30 that extends from the base portion 10 to the knee portion 50, and a lower leg portion 70 that extends from the knee portion 50 to the foot portion 90. The upper leg portion 30 has a first parallel link mechanism that moves the knee portion 50 relatively parallel to the upper surface of the base portion 10 in the front-rear direction, and in a side view, moves the upper leg portion 30 back and forth between a state in which it extends vertically from the base portion 10 and a state in which it is tilted diagonally forward from the base portion 10, and a second parallel link mechanism that moves the knee portion 50 relatively parallel to the upper surface of the base portion 10 in the left-right direction, and in a front view, moves the upper leg portion 30 back and forth between a state in which it is tilted diagonally downward to the left from the base portion 10 and a state in which it is tilted diagonally downward to the right from the base portion 10. The lower leg portion 70 has a third parallel link mechanism that, while keeping the lower surface of the foot portion 90 horizontal, moves the foot portion 90 in parallel relative to the knee portion 50 in the direction of travel, causing the lower leg portion 70 to reciprocate between a state in which it extends vertically from the knee portion 50 and a state in which it is inclined diagonally backward from the knee portion 50 in a side view, and a fourth parallel link mechanism that, while keeping the lower surface of the foot portion 90 horizontal, moves the foot portion 90 in parallel relative to the knee portion 50 in the left-right direction, causing the lower leg portion 70 to reciprocate between a state in which it is inclined diagonally downward to the left from the knee portion 50 and a state in which it is inclined diagonally downward to the right from the knee portion 50 in a front view.

[0070] These left and right legs 1L and 1R have a second parallel link in the upper leg 30 and a fourth parallel link in the lower leg 70. Therefore, while maintaining the lower surface of the foot 90 horizontally, the inclination of the upper leg 30 and the inclination of the lower leg 70 can be changed to be the same in a front view, while the knee 50 can be moved relatively parallel to the upper surface of the hip joint 10 in the left-right direction, and the foot 90 can be moved relatively parallel to the knee 50 in the left-right direction. In other words, these left and right legs 1L and 1R can not only move the foot 90 in the front-back direction relative to the hip joint 10 while maintaining the lower surface of the foot 90 horizontally, but can also move the foot 90 in the left-right direction relative to the hip joint 10 in a front view. For this reason, a bipedal walking robot equipped with these left and right legs 1L and 1R can easily shift its center of gravity to one of the left and right legs 1L and 1R, and move the other of the left and right legs 1L and 1R in the direction of travel, enabling it to walk on two legs smoothly. Furthermore, since the left and right legs 1L and 1R have a simple structure, they can be miniaturized. Therefore, a bipedal robot equipped with these left and right legs 1L and 1R can be made into a small robot.

[0071] Therefore, the left and right legs 1L and 1R of Example 1 have a simple structure, and a bipedal robot equipped with these left and right legs 1L and 1R can walk on two legs well.

[0072] The left and right legs 1L and 1R of Embodiment 1 are equipped with a first motor M1 that drives the first parallel link mechanism, a second motor M2 that drives the third parallel link mechanism, and a third motor M3 that drives the second and fourth parallel link mechanisms. Therefore, a bipedal walking robot equipped with these left and right legs 1L and 1R can walk well by controlling the driving of the first motor M1 to the third motor M3.

[0073] In the left and right leg sections 1L and 1R of Embodiment 1, the first motor M1, the second motor M2, and the third motor M3 are provided in the knee section 50. Therefore, by providing each motor in the knee section 50, the left and right leg sections 1L and 1R can directly drive each parallel link with a simple structure, thus enabling miniaturization.

[0074] The robot is equipped with left and right legs 1L and 1R as in Embodiment 1, and further includes an opening / closing drive unit that moves the feet 90 of the left and right legs 1L and 1R back and forth between a parallel position and a position with the front ends of the feet 90 open. As a result, the opening / closing mechanism 20 moves the left and right legs 1L and 1R back and forth between a position where the left and right feet 90 are arranged in parallel and a position where the front ends of the feet 90 are open, and each motor drives each parallel link mechanism, thereby changing the orientation of the bipedal walking robot.

[0075] The bipedal robot of Example 1 is equipped with left and right legs 1L and 1R. This bipedal robot can walk on two legs well. Furthermore, because the left and right legs 1L and 1R of this bipedal robot are constructed with a simple structure, miniaturization can be achieved, resulting in a compact robot.

[0076] The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments, for example, are also included in the technical scope of the present invention. (1) In Embodiment 1, the first drive shaft member to the third drive shaft member were rotated by the first motor to the third motor provided at the knee portion, but the first drive shaft member to the third drive shaft member may be rotated by other means. (2) Although the first embodiment included an opening and closing mechanism, it is not necessary to include such a mechanism. (3) The components that make up the left and right legs may be of other shapes. [Explanation of symbols]

[0077] 1L, 1R…Left and right legs (legs for biped robots) (1L…Left leg, 1R…Right leg) 10... Base 20…Opening and closing mechanism 30...Upper leg 50...knee area 70...lower leg 90...foot M1…First motor (first drive unit) M2…Second motor (second drive unit) M3…Third motor (third drive unit)

Claims

1. When a bipedal robot is standing upright on a horizontal plane, The base portion, on which the torso is placed, has an upper surface parallel to the horizontal plane, The knee area, A foot portion whose lower surface is in contact with the horizontal surface parallel to the horizontal surface, The upper leg portion comprising the part from the base to the knee, The lower leg portion comprising the knee portion to the foot portion, A leg for a bipedal robot, comprising: The aforementioned upper leg portion is, A first parallel link mechanism moves the knee portion in parallel relative to the direction of travel with respect to the upper surface of the base portion, and in a side view taken from a direction perpendicular to the direction of travel, the upper leg portion reciprocates between a state in which it extends vertically from the base portion and a state in which it is inclined diagonally forward from the base portion. A second parallel link mechanism moves the knee portion relative to the upper surface of the base portion in a direction perpendicular to the direction of travel, and in a front view from the front in the direction of travel, the upper leg portion reciprocates between a state in which it is tilted diagonally downward to the left from the base portion and a state in which it is tilted diagonally downward to the right from the base portion. It has, The aforementioned lower leg portion is, A third parallel link mechanism that, while maintaining the lower surface of the foot horizontal, moves the foot in parallel relative to the knee in the direction of travel, causing the lower leg to reciprocate between a state in which it extends vertically from the knee and a state in which it is inclined diagonally backward from the knee, in a side view. A fourth parallel link mechanism that, while maintaining the lower surface of the foot horizontal, moves the foot in a direction perpendicular to the direction of travel relative to the knee, causing the lower leg to reciprocate between a state in which it is tilted diagonally downward to the left from the knee and a state in which it is tilted diagonally downward to the right from the knee, in a front view. A leg for a bipedal robot.

2. The first drive unit drives the first parallel link mechanism, The second drive unit drives the third parallel link mechanism, A third drive unit that drives the second parallel link mechanism and the fourth parallel link mechanism, A leg for a bipedal robot according to claim 1, comprising:

3. The leg for a bipedal walking robot according to claim 2, wherein the first drive unit, the second drive unit, and the third drive unit are provided in the knee portion.

4. The robot is provided with a pair of bipedal robot legs as left and right legs, according to any one of claims 1 to 3. Furthermore, the legs of the bipedal robot are equipped with an opening and closing mechanism that moves the foot of each leg of the bipedal robot back and forth between a parallel position and a position with the front end of the foot open.

5. A bipedal robot having a pair of bipedal robot legs as left and right legs, as described in any one of claims 1 to 3.

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