JP6705658B2 - Legged mobile robot - Google Patents

Description

The present invention relates to a legged mobile robot including a body and a leg rotatably connected to the body around a pitch axis, a roll axis and a yaw axis.

A legged mobile robot is known that includes a body and a leg that is rotatably connected to the body around a pitch axis, a roll axis, and a yaw axis. Like human hip joints, the pitch axis is the axis when swinging the leg back and forth, the roll axis is the axis when opening the leg left and right, and the yaw axis is the axis when twisting the leg. is there. In order to drive the legs, a rotary motor and a speed reducer are incorporated in each of the pitch axis, the roll axis, and the yaw axis that make up the hip joint. Generally, a load is applied to the hip joint, and high rigidity is required for each axis. The conventional legged mobile robot has a problem that each axis tends to increase in size in order to secure necessary rigidity.

As a legged mobile robot that solves this problem, in Patent Document 1, two linear motion actuators that act like human muscles are used, and the legs are rotated around a pitch axis and a roll axis with respect to the body. What is driven to rotate is disclosed. This legged mobile robot includes a body portion, a swing frame rotatably connected to the body portion around a yaw axis, and a leg portion rotatably connected to the swing frame around a pitch axis and a roll axis. And One linear motion actuator is connected between the body portion and the swivel frame, and the swivel frame is configured to rotate around the yaw axis by expanding and contracting one linear motion actuator. Two linear motion actuators are connected between the swivel frame and the leg portions, and the leg portions are configured to rotate around the pitch axis and the roll axis by simultaneously expanding and contracting the two linear motion actuators. According to this legged mobile robot, a rotary motor and a speed reducer are not incorporated in each of the pitch axis, the roll axis, and the yaw axis, and the hip joint structure of the legged mobile robot can be miniaturized.

International Publication No. 2009/054103

However, in the legged mobile robot described in Patent Document 1, it is difficult to increase the rigidity of the hip joint, and there is a problem that the legs sway. It is presumed that one of the causes is that the rotation about the pitch axis with a large swinging angle range and the rotation around the roll axis with a small swinging angle range are performed using two linear motion actuators. It

Also, when the legged mobile robot crouches, that is, when the forward swing angle around the pitch axis of the thigh of the leg becomes large, the rotation around the roll axis of the thigh of the leg cannot be controlled. There is also the issue that there are cases.

Therefore, an object of the present invention is to provide a legged mobile robot capable of constructing a compact hip joint structure having high rigidity.

In order to solve the above-mentioned problems, the present invention is rotatably connected to a torso portion and a pelvis frame of the torso portion via a universal joint so as to be rotatable around a yaw axis and a roll axis, and protrudes above and below the pelvis frame. A hip joint portion, a leg portion that is rotatably connected to the hip joint portion around a pitch axis, is arranged on the upper side of the pelvic frame, and is connected to the body portion and the hip joint portion on the upper side of the pelvic frame , A first actuator that changes a distance from a connection portion with the body portion to a connection portion with the hip joint portion; and a hip joint portion that is disposed below the pelvis frame and that is below the body portion and the pelvis frame. And a second actuator that changes a distance from a connection portion with the body portion to a connection portion with the hip joint portion, wherein the first and second actuators operate at the same time, A legged mobile robot configured to rotate the hip joint section around the yaw axis and the roll axis with respect to the body section.

According to the present invention, the first and second actuators are used to rotate the hip joint section around the yaw axis and the roll axis, which have a smaller angular range of swing than the pitch axis. Therefore, a compact and highly rigid hip joint structure can be constructed.

It is a perspective view of the legged mobile robot of one embodiment of the present invention. It is a perspective view of a hip joint structure of a leg type mobile robot of this embodiment. It is a top view of the hip joint structure of the leg type mobile robot of this embodiment. It is a front view of a hip joint structure of a legged mobile robot of this embodiment. It is a perspective view of a universal joint of the legged mobile robot of the present embodiment. It is an exploded perspective view of a universal joint of the legged mobile robot of this embodiment. It is a figure of the thigh of the legged mobile robot of this embodiment. It is a perspective view of the ankle joint structure of the legged mobile robot of this embodiment. It is a side view of the ankle joint structure of the legged mobile robot of the present embodiment.

Hereinafter, a legged mobile robot according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention can be embodied in various forms and is not limited to the embodiments described herein. This embodiment is provided with the intention of making it possible for those skilled in the art to fully understand the scope of the invention by sufficiently disclosing the specification. In addition, in the accompanying drawings, the same components are denoted by the same reference numerals.
(Overall structure of legged mobile robot)

FIG. 1 shows a perspective view of a legged mobile robot according to an embodiment of the present invention. The legged mobile robot includes a body portion 1, two leg portions 2 arranged below the body portion 1, two arm portions 3 installed on both left and right side surfaces of the body portion 1, and a body portion 1. One head 4 (actually, the head mounted with the CCD camera is fixed to the member of reference numeral 4) installed above the. In the following description, front-rear, top-bottom, left-right refer to front-back, top-bottom, left-right when viewed from a legged mobile robot. The front-back direction is the x-axis direction, the left-right direction is the y-axis direction, and the up-down direction is the z-axis direction. The x axis is the roll axis, the y axis is the pitch axis, and the z axis is the yaw axis. Further, the legged mobile robot is viewed from the front when viewed from the front, and the legged mobile robot is viewed from above when viewed from above.

The legged mobile robot is also called a bipedal walking robot, and walks while balancing with two legs 2 like a human. The leg portion 2 includes a thigh portion 6, a shin portion 8 rotatably connected to the lower portion of the thigh portion 6 via a knee joint 7 around a pitch axis (y axis), and below the shin portion 8. A foot portion 10 rotatably connected around a pitch axis (y axis) and a roll axis (x axis) via a universal joint 9.

The two arm portions 3 are configured to be freely movable around the body portion 1. The arm portion 3 includes an upper arm portion 11 closer to the shoulder, a lower arm portion 12 closer to the hand portion (not shown), and a wrist joint 13 provided at the tip of the lower arm portion 12. A hand part (not shown) is connected to the wrist joint 13.

A head 4 is connected above the body 1 via a neck joint 14 so as to be swingable around a yaw axis (z axis) and a pitch axis (y axis).
(Hip joint structure of legged mobile robot)

2 and 3 are detailed views of the hip joint structure of the legged mobile robot of this embodiment. 2 shows a perspective view of the hip joint structure, and FIG. 3 shows a plan view of the hip joint structure. 2 and 3, the cover shown in FIG. 1 is removed to show the inside of the hip joint structure.

The body part 1 is provided with a substantially quadrangular plate-like pelvic frame 16 at its lower part. The pelvis frame 16 is configured such that two legs 2 are rotatable via a hip joint 21 around a yaw axis (z axis), a roll axis (x axis), and a pitch axis (y axis). The two legs 2 are bilaterally symmetrical.

The hip joint portion 21 projects above and below the pelvic frame 16. The hip joint portion 21 is rotatably connected to the pelvis frame 16 via a universal joint 17 about a yaw axis (z axis) and a roll axis (x axis). To the lower part of the hip joint 21, the thigh 6 of the leg 2 is rotatably connected around the pitch axis (y-axis, see axis 22).

The two hip joints 21 are driven by two sets of first and second actuators 23 and 24. The two sets of first and second actuators 23 and 24 are symmetrically arranged on the pelvic frame 16. The first actuator 23 includes a linear motion actuator 31 as a drive source, a link 32, and an arm 33. The second actuator 24 includes a linear actuator 34 as a drive source, a link 35, and an arm 36. The first actuator 23 is arranged above the pelvic frame 16. The second actuator 24 is arranged below the pelvic frame 16.

The linear actuator 31 of the first actuator 23 includes a rotary motor 27, a ball screw nut 28 that is rotationally driven by the rotary motor 27, and a screw shaft 29 that is screwed into the ball screw nut 28. The linear actuator 31 is configured such that when the rotary motor 27 rotationally drives the ball screw nut 28, the screw shaft 29 moves in the axial direction. The rotation motor 27 is rotatably connected to the pelvis frame 16 about a yaw axis (z axis). The tip end of the screw shaft 29 is rotatably connected to the link 32 about the yaw axis (z axis).

The link 32 of the first actuator 23 is U-shaped. The screw shaft 29 is rotatably connected to the bifurcated end portion of the link 32 about the yaw axis (z axis). An arm 33 is rotatably connected to the other end of the link 32 via a ball joint. An intermediate shaft 38 is provided between one end and the other end of the link 32. The link 32 is connected to the pelvis frame 16 by an intermediate shaft 38 so as to be rotatable about a yaw axis (z axis). The lever ratio of the link 32 is set such that the length of the link 32 from the intermediate shaft 38 to one end is longer than the length from the intermediate shaft 38 to the other end. The intermediate shaft 38 of the link 32 is a connecting point P1 between the first actuator 23 and the body portion 1.

The arm 33 has a rod shape. One end of the arm 33 is rotatably connected to the link 32 via a ball joint. The other end of the arm 33 is rotatably connected to the hip joint 21 via a ball joint. The other end of the arm 33 is a connection point P2 between the first actuator 23 and the hip joint 21.

The second actuator 24 also includes a linear motion actuator 34 as a drive source, a link 35, and an arm 36. The first actuator 23 and the second actuator 24 are vertically symmetrical with respect to the pelvic frame 16. The configurations of the linear motion actuator 34, the link 35, and the arm 36 of the second actuator 24 are the same as those of the linear motion actuator 31, the link 32, and the arm 33 of the first actuator 23, and thus detailed description thereof will be omitted. The rotation center of the linear motion actuator 31 of the first actuator 23 and the rotation center of the linear motion actuator 34 of the second actuator 24 coincide with each other. Further, the center of the intermediate shaft 38 of the link 32 and the center of the intermediate shaft 39 of the link 35 coincide with each other.

When the linear motion actuator 31 of the first actuator 23 expands and contracts, the link 32 rotates around the intermediate shaft 38. With the rotation of the link 32, the distance from the connection point P1 between the first actuator 23 and the body portion 1 to the connection point P2 between the first actuator 23 and the hip joint portion 21 changes.

Even if the linear actuator 34 of the second actuator 24 expands and contracts, the link 35 rotates around the intermediate shaft 39. With the rotation of the link 35, the distance from the connection point P3 between the second actuator 24 and the body portion 1 to the connection point P4 between the second actuator 24 and the hip joint portion 21 changes.

When the linear actuators 31 and 34 of the first and second actuators 23 and 24 expand or contract at the same time, the links 32 and 35 simultaneously rotate around the intermediate shafts 38 and 39 in the clockwise direction or the counterclockwise direction, and the hip joint portion 21. Rotates around the yaw axis (z axis). When one of the first and second actuators 23 and 24 extends and the other contracts, the link 32 and the link 35 rotate about the intermediate shafts 38 and 39 in opposite directions. Then, the hip joint 21 rotates around the roll axis (x axis). When the expansion/contraction amounts of the linear motion actuators 31, 34 of the first and second actuators 23, 24 are made different, the hip joint portion 21 rotates around both the yaw axis (z axis) and the roll axis (x axis).

As shown in FIG. 3, in a plan view, the linear motion actuator 31, the link 32, and the arm 33 of the first actuator 23 are arranged so as to be folded back from the center of the pelvic frame 16 in the left-right direction. That is, the linear motion actuator 31, the link 32, and the arm 33 are arranged in a U shape. The linear actuator 31, the link 32, and the arm 33 may be arranged so as to be folded back from the end portion in the left-right direction of the pelvis frame 16, instead of the center in the left-right direction. The arrangement of the linear actuator 34, the link 35, and the arm 36 of the second actuator 24 is also the same.

In addition, when the two legs 2 are in the vertical direction in a front view, the connection point P2 between the arm 33 of the first actuator 23 on the upper side and the hip joint portion 21, the second actuator 24 on the lower side, and the hip joint portion 21. And a connection point P4 with respect to the vertical line L1 are displaced from each other so that the opening angle of the two legs 2 can be increased. In this embodiment, the connection point P2 is arranged outside the vertical line L1, and the connection point P4 is arranged inside the vertical line L1 (see also FIG. 4 when the hip joint portion 21 is viewed from the front). The angle at which the two legs 2 rotate in the opening direction around the roll axis (x axis) is larger than the angle at which the two legs 2 rotate in the closing direction around the roll axis (x axis). This is because when the two legs 2 rotate in the closing direction around the roll axis (x axis), the two legs 2 come into contact with each other. By arranging the connecting portion P2 and the connecting portion P4 so as to be laterally offset with respect to the vertical line L1, the opening angle of the two leg portions 2 can be increased.
(Structure of universal joint)

FIG. 5 shows a perspective view of a universal joint 17 that rotatably connects the pelvis frame 16 and the leg 2 about a roll axis (x axis) and a yaw axis (z axis). FIG. 6 shows an exploded perspective view of the universal joint 17.

The universal joint 17 is fixed to the pelvic frame 16, an outer ring 41, an inner ring 42 that is rotatable around a yaw axis (z axis, see reference numeral 44) with respect to the outer ring 41, and is fixed to the inner ring 42. And a shaft 43 that rotatably supports the shaft. A large number of rolling elements are interposed between the outer ring 41 and the inner ring 42 so that they can roll. The outer ring 41 and the inner ring 42 form, for example, a cross roller bearing 40.

The block 45 is fixed to the inner side of the inner ring 42 by a fastening member 48. The block 45 has an opening 45a having a quadrangular cross section that penetrates in the direction of the yaw axis (z axis, see reference numeral 44). The shaft 43 is fixed to the block 45. The shaft 43 faces the direction of the roll shaft (x-axis, see reference numeral 49). The hip joint 21 is supported on the shaft 43 via bearings 47a and 47b so as to be rotatable around a roll shaft (x-axis, see reference numeral 49).
(Thigh structure of legged mobile robot)

FIG. 7 shows the third and fourth linear motion actuators 61 and 62 for rotating the thigh 6 around the pitch axis (y axis) with respect to the hip joint 21. Each of the third and fourth linear motion actuators 61 and 62 includes a rotary motor 63, a ball screw nut 64 that is rotationally driven by the rotary motor 63, and a screw shaft 65 that is screwed into the ball screw nut 64, and is configured to rotate. When the motor 63 rotationally drives the ball screw nut 64, the screw shaft 65 is configured to move in the axial direction. The rotary motors 63 of the third and fourth linear motion actuators 61, 62 are rotatably connected to the thigh 6 around the pitch axis P5 (y axis), and the screw shaft 65 is attached to the hip joint 21 at the pitch axis P6 (y. ) Is rotatably connected about a shaft. By simultaneously expanding and contracting the third linear motion actuator 61 and the fourth linear motion actuator 62, the thigh 6 can be rotationally driven around the pitch axis (y axis) with respect to the hip joint portion 21.
(Knee joint structure of legged mobile robot)

The knee joint 7 shown in FIG. 1 is provided with a drive device that rotationally drives the shin 8 with respect to the thigh 6 around the pitch axis (y axis). The drive device may be composed of a rotary motor and a speed reducer, or may be composed of a linear actuator.
(Ankle joint structure of legged mobile robot)

8 shows a perspective view of the ankle joint structure, and FIG. 9 shows a side view of the ankle joint structure. A foot 10 is connected to the shin 8 via a universal joint 9 so as to be rotatable around a pitch axis (y axis) and a roll axis (x axis). The structure of the universal joint 9 is the same as that of the universal joint 17 shown in FIGS.

The foot portion 10 is rotationally driven about the pitch axis (y axis) and the roll axis (x axis) with respect to the shin portion 8 by the fifth and sixth actuators 51 and 52. The fifth actuator 51 and the sixth actuator 52 are bilaterally symmetrical. The fifth actuator 51 includes a direct acting actuator (not shown) as a drive source (see the direct acting actuator 56 in FIG. 9 ), a link 54, and an arm 55.

The structure of the linear motion actuator of the fifth actuator 51 is substantially the same as that of the linear motion actuator 31 of the first actuator 23. The rotation motor of the linear motion actuator is rotatably connected to the shin 8 about a pitch axis (y axis). The screw shaft of the linear actuator is rotatably connected to one end of the link 54.

One end of an arm 55 is rotatably connected to the other end of the link 54 via a ball joint. An intermediate shaft (see intermediate shaft 59 in FIG. 9) is provided between one end and the other end of the link 54. The link 54 is rotatably connected to the shin 8 about the pitch axis (y axis) by an intermediate shaft 59. The other end of the arm 55 is rotatably connected to the foot portion 10 via a ball joint.

Like the fifth actuator 51, the sixth actuator 52 also includes a linear actuator 56 as a drive source, a link 57, and an arm 58. The configurations of the linear actuator 56, the link 57, and the arm 58 of the sixth actuator 52 are the same as those of the linear actuator, the link 54, and the arm 55 of the fifth actuator 51, and thus detailed description thereof will be omitted.

By simultaneously expanding and contracting the fifth and sixth actuators 51, 52, the foot 10 can be rotationally driven about the pitch axis (y axis) and the roll axis (x axis) with respect to the shin 8.

The structure of the legged mobile robot of this embodiment has been described above. The legged mobile robot of this embodiment has the following effects.

Using the first and second actuators 23 and 24, rotate the hip joint portion 21 around the yaw axis (z axis) and the roll axis (x axis) whose swing range is smaller than that of the pitch axis (y axis). Let Therefore, a compact and highly rigid hip joint structure can be constructed.

Since the first and second actuators 23 and 24 include the linear motion actuators 31 and 34, the links 32 and 35, and the arms 33 and 36, the reaction force acting on the leg portion 2 can be temporarily received by the links 32 and 35. .. Since it is possible to prevent the reaction force acting on the leg portion 2 from directly acting on the linear actuators 31 and 34, it is possible to prevent a twist, a moment or the like from acting on the linear actuators 31 and 34.

In a plan view, the linear motion actuators 31 and 34 of the first and second actuators 23 and 24, the links 32 and 35, and the arms 33 and 36 are arranged so as to be folded back. And the second actuators 23, 24 can be arranged.

Since the first and second actuators 23 and 24 are arranged vertically, it is possible to construct a small hip joint structure that rotates the hip joint portion 21 around the yaw axis (z axis) and the roll axis (x axis).

In a front view, the connection point P2 between the upper first actuator 23 and the hip joint portion 21 and the connection point P4 between the lower second actuator 24 and the hip joint portion 21 are displaced left and right with respect to the vertical line L1. Therefore, the opening angle of the two legs 2 can be increased.

Since the leg portion 2 is rotationally driven about the pitch axis (y axis) with respect to the hip joint portion 21 using the third and fourth linear motion actuators 61 and 62, the leg portion 2 is rotated about the pitch axis (y axis). The torque can be increased, and rattling between the hip joint portion 21 and the leg portion 2 can be eliminated.

Since the universal joint 17 that connects the body portion 1 and the hip joint portion 21 includes the outer race 41, the inner race 42, and the shaft 43 fixed to the inner race 42, a compact and highly rigid universal joint can be constructed.

The present invention is not limited to being embodied in the above-described embodiment, and can be changed to other embodiments without changing the gist of the present invention.

The configurations and arrangements of the first and second actuators are examples, and other configurations and arrangements can be adopted.

For example, in the above embodiment, the linear actuator is used to rotationally drive the links of the first and second actuators, but a rotary motor can also be used.

In the above embodiment, the first and second actuators are composed of the linear motion actuator, the link, and the arm, but the first and second actuators may be composed of only the linear motion actuator. In this case, both ends of the linear motion actuator are connected to the pelvis frame and the thigh via the universal joint.

In the above embodiment, an example in which the legged mobile robot has two legs has been described, but it is also possible to have four legs like a quadruped robot.

DESCRIPTION OF SYMBOLS 1... Body part, 2... Leg part, 6... Thigh part, 16... Pelvic frame (body part), 17... Universal joint, 21... Hip joint part, 23... 1st actuator, 24... 2nd actuator, 31... Straight Dynamic actuator, 32... Link, 33... Arm, 34... Linear actuator, 35... Link, 36... Arm, 40... Cross roller bearing, 41... Outer ring, 42... Inner ring, 43... Shaft, 61... Third linear motion actuator , 62... Fourth linear motion actuator, L1... Vertical line, P1... Connection portion between first actuator and body portion, P2... Connection portion between first actuator and hip joint portion, P3... Connection between second actuator and body portion Connection point, P4... Connection point between second actuator and hip joint

Claims (6)

Body part,
A hip joint portion that is rotatably connected to the pelvic frame of the body portion via a universal joint around a yaw axis and a roll axis , and that projects vertically from the pelvic frame .
A leg portion rotatably connected to the hip joint portion about a pitch axis;
First arranged on the upper side of the pelvis frame , connected to the body and the hip joint on the upper side of the pelvis frame, and changing a distance from a connection point with the body section to a connection point with the hip joint An actuator,
It is arranged on the lower side of the pelvic frame and is connected to the body and the hip joint on the lower side of the pelvis frame, and changes the distance from the connection point with the body section to the connection point with the hip joint section. A second actuator,
The legged mobile robot configured to rotate the hip joint section around the yaw axis and the roll axis with respect to the body section by simultaneously operating the first and second actuators. Each of the first and second actuators is
A link rotatably connected to the body,
A linear motion actuator rotatably connected to the body portion and rotatably connected to the link;
The legged mobile robot according to claim 1, further comprising an arm rotatably connected to the hip joint and rotatably connected to the link. The legged mobile robot includes two legs,
In a plan view, the linear actuator, the link, and the arm are folded back so that two sets of the first and second actuators that drive the two leg portions can be arranged on the left and right of the body portion. The legged mobile robot according to claim 2, wherein the legged mobile robot is arranged in the. The legged mobile robot includes two legs,
In a front view, when the two legs are in the vertical direction, an upper connection point between the first actuator and the hip joint section and a lower connection point between the second actuator and the hip joint section are The legged mobile robot according to any one of claims 1 to 3, wherein the legged mobile robot is shifted to the left and right with respect to the vertical line so that the opening angle of the two legs can be increased. The legged mobile robot,
A third and a fourth linear motion actuator connected to the hip joint and the leg,
2. The third and fourth linear motion actuators are configured to rotate the leg portions around the pitch axis with respect to the hip joint portion by operating at the same time. The legged mobile robot according to any one of items 1 to 4 . The joint structure of the legged mobile robot is
An outer ring fixed to one of the body portion and the hip joint portion,
An inner ring rotatable with respect to the outer ring,
It is fixed to the inner ring, the body portion and the leg type according to any one of claims 1 to 5, characterized in that it comprises a universal joint having a shaft for rotatably supporting the other of said hip portion Mobile robot.

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