JP2011206874A - Leg type mobile robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leg type mobile robot, expanding a landing enabling range of an idling leg.SOLUTION: This robot 1 includes: an upper body 4; a hip joint joining the upper body 4 to an upper thigh links 30R (L), 32R (L); a knee joint joining the upper thigh links 30R (L), 32R (L) to a lower thigh link 34R (L); and an ankle joint joining the lower thigh link 34R (L) to a foot 22R (L). Accordingly, the robot 1 has two leg bodies 2R, 2L formed bilaterally symmetric and moves by driving the leg bodies 2R, 2L. The hip joint has a hip joint yawing shaft part 10R (L) rotating in the yawing direction, and when the robot 1 advances linearly, the rotating angle in the yawing direction of a first upper thigh link 30R (L) to the upper body 4 is set in the hip joint yawing shaft part 10R (L) so that the upper thigh links 30R (L), 32R (L) of the leg body 2R (L) serving as a support leg direct ahead obliquely outward with respect to the upper body 4.

Description

  The present invention relates to a legged mobile robot, and more particularly to a legged mobile robot having symmetrical legs.

  A bilaterally symmetric leg having an upper body, a hip joint that connects the upper body and the upper leg link, a knee joint that connects the upper leg link and the lower leg link, and an ankle joint that connects the lower leg link and the foot. There is known a legged mobile robot that moves by driving each leg.

  For example, Patent Document 1 discloses a humanoid robot in which a hip joint has a roll axis, a pitch axis, and a yaw axis, a knee joint has a pitch axis, and an ankle joint has a pitch axis and a roll axis. In this humanoid robot, the roll axis direction of the hip joint yaw axis is offset from the intersection of the hip joint roll axis and the pitch axis. As a result, the center of rotation of the foot is offset from the center of rotation of the ankle, and interference between the left and right foot that occurs when the yaw axis of one hip joint is rotated when the foot changes direction can be reduced. .

Japanese Patent No. 3345666

  However, in the legged mobile robot as disclosed in Patent Document 1, when the knee joint of the leg serving as the support leg is bent, the knee does not shift in the left-right direction. Therefore, when the free leg is moved to the support leg side, interference between the left and right knee portions occurs. Therefore, the cornering radius is large, and the landing possible range of the free leg is narrow. Along with this, there is a problem that the degree of freedom of gait is small.

  In view of the above points, an object of the present invention is to provide a legged mobile robot capable of widening the landing possible range of a free leg.

  The present invention includes an upper body, a hip joint that connects the upper body and the upper leg link, a knee joint that connects the upper leg link and the lower leg link, and an ankle joint that connects the lower leg link and the foot. A legged mobile robot having symmetrical legs and moving by driving each leg, wherein the hip joint has a rotating shaft that rotates in the yaw direction. A rotation angle around the yaw direction of the upper thigh link with respect to the upper body at the rotation shaft portion so that the upper thigh link of the leg serving as a support leg faces obliquely forward and outward with respect to the upper body. Is set.

  According to the present invention, when the knee joint of the leg serving as the support leg is bent, the knee is in the front outer direction (pitch axis direction toward the side where the leg is located with respect to the center of the upper body). Moving. Therefore, as in the legged mobile robot disclosed in the above-mentioned Patent Document 1, when the knee joint of the leg serving as the support leg is bent, the knee part moves straight ahead as compared with the case where the knee moves straight forward. Interference between the knees can be suppressed. Therefore, it is possible to move in the direction approaching the support leg. Therefore, the cornering radius is reduced and the landing possible range of the free leg is expanded. Accordingly, the degree of freedom of gait increases, and the legged mobile robot can perform various operations.

  Furthermore, since there is no need to increase the rotating shaft portion, problems such as an increase in size and weight associated with a complicated configuration and difficulty in control associated with an increase in the degree of freedom do not occur.

  In the present invention, it is preferable that when the legged mobile robot goes straight, the foot of the leg serving as a support leg faces the front.

  In the present invention, a six-axis force sensor is provided between the foot and the ankle joint, and a sensitivity center line in one direction of the six-axis force sensor is parallel to a straight direction of the legged mobile robot. It is preferable.

  In this case, since the 6-axis force sensor can detect each component of the floor reaction force transmitted from the floor to each leg via the foot, it is necessary to convert each detected component. Absent.

  In the present invention, it is preferable that the ankle joint has a pitch rotation shaft portion that rotates in the pitch direction, and the axis of the pitch rotation shaft portion is inclined so that the inner side in the left-right direction is lower than the outer side.

  In this case, when the knee joint of the leg serving as the support leg is bent, the knee moves in the forward outward direction (pitch axis direction toward the side where the leg is located with respect to the center of the upper body). Therefore, as in the legged mobile robot disclosed in the above-mentioned Patent Document 1, when the knee joint of the leg serving as the support leg is bent, the knee part moves straight ahead as compared with the case where the knee moves straight forward. Interference between the knees can be suppressed. Therefore, it becomes possible to move in the direction closer to the support leg.

1 is a perspective view showing a schematic configuration of a biped mobile robot according to a first embodiment of the present invention. The front view of a leg. Side view of the leg. Top view of the foot. Sectional drawing of a foot. The top view of a foot in the state which removed the bearing block. The top view which shows a left-right leg body roughly. The graph which shows the relationship between a knee joint angle and the left-right direction movement distance of a knee part. The front view of the leg body of the biped mobile robot which concerns on 2nd Embodiment of this invention.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described by taking a biped robot as an example of a legged mobile robot.

  As shown in FIG. 1, a bipedal mobile robot 1 (hereinafter simply referred to as “robot 1”) according to the present embodiment includes a pair of left and right legs 2R and 2L. The upper body 4 is connected to the base ends (upper end portions) of both legs 2R, 2L, and the upper body 4 is supported above the floor surface by the legs 2R, 2L contacting the floor.

  Both legs 2R and 2L have the same structure, and each has six joint shafts. The six joint shaft portions are, in order from the upper body 4 side, hip joint yaw shaft portions 10R and 10L for rotation of the hip joint (for rotation in the yaw direction (around the Z axis) with respect to the upper body 4), and the roll direction of the hip joint Hip joint roll shafts 12R, 12L for rotation (around the X axis), hip pitch shaft portions 14R, 14L for rotation in the pitch direction of the hip joint (around the Y axis), and knees for rotation in the pitch direction of the knee joint The joint pitch shaft portions 16R and 16L, the ankle joint pitch shaft portions 18R and 18L for rotation in the pitch direction of the ankle joint, and the ankle joint roll shaft portions 20R and 20L for rotation in the roll direction of the ankle joint are configured. . Further, a foot 22R (L) is provided at the tip (lower end) of each leg 2.

  In the description of this embodiment, the symbols R and L mean that they correspond to the right leg and the left leg, respectively. The X-axis direction corresponds to the front-rear direction (traveling direction, roll axis direction) of the robot 1, and the Y-axis direction corresponds to the left-right direction (pitch axis direction) of the robot 1. The Z-axis direction is the vertical direction (gravity direction) and corresponds to the vertical direction (yaw axis direction) of the robot 1. In this case, in the present embodiment, the positive X-axis direction has the meaning as the straight direction of the robot 1 in the present invention.

  The joint shaft portions 10R (L), 12R (L), and 14R (L) of each leg 2R (L) constitute a three-degree-of-freedom hip joint, and the joint shaft portion 16R (L) forms a one-degree-of-freedom knee joint. An ankle joint having two degrees of freedom is configured by the joint shaft portions 18R (L) and 20R (L). Each leg 2R (L) is connected to the upper body 4 via a hip joint.

  The hip joint connects the upper body 4 and the upper leg links 30R (L), 32R (L), and the knee joint connects the upper leg links 30R (L), 32R (L) and the lower leg links 34R (L), The ankle joint connects the lower leg link 34R (L) and the foot 22R (L).

  Specifically, the hip joint yaw shaft portion 10R (L), the hip joint roll shaft portion 12R (L), and the hip joint pitch shaft portion 14R (L) are connected by the first upper leg link 30R (L), and the hip joint roll shaft portion 12R. (L) and the hip joint pitch shaft portion 14R (L) and the knee joint pitch shaft portion 16R (L) are connected by the second upper leg link 32R (L), and the knee joint pitch shaft portion 16R (L) and the ankle joint roll. The shaft portion 18R (L) and the ankle joint pitch shaft portion 20R (L) are connected by a crus link 34R (L).

  With the above-described configuration of each leg 2R (L), the foot 22R (L) of each leg 2R (L) has six degrees of freedom with respect to the upper body 4. Then, when the robot 1 moves, both legs 2R and 2L are combined and 6 × 2 = 12 joints are driven at appropriate angles, whereby the desired motion of both legs 2R and 2L can be performed. Thereby, the robot 1 can perform a movement that moves in a three-dimensional space, such as a walking action and a running action.

  In addition, although illustration is abbreviate | omitted, in this embodiment, while a pair of right and left arm bodies are attached to the both sides of the upper part of the upper body 4, a head is mounted on the upper end part of the upper body 4. Each arm body can perform a motion such as swinging the arm body back and forth with respect to the upper body 4 by a plurality of joints (shoulder joint, elbow joint, wrist joint, etc.) provided therein. . However, these arms and heads may be omitted.

  A 6-axis force sensor 36R (L) is interposed between the ankle joint of each leg 2R (L) and the foot 22R (L). The six-axis force sensor 36R (L) is a force component in the three axial directions and a moment component around the three axes of the floor reaction force transmitted from the floor to each leg 2R (L) via the foot 22R (L). And a detection signal is output to a control unit (not shown).

  Next, the configuration of the leg 2R (L) will be described. Note that the leg 2R (L) is bilaterally symmetric, and here, the right leg 2R will be described. FIG. 3 omits some of the constituent members.

  As shown in FIGS. 2 and 3, an electric motor 40 that drives the hip joint yaw shaft portion 10 </ b> R is disposed in the lower portion of the upper body 4. The output of the electric motor 40 is decelerated by the speed reducer 42 connected to the output shaft of the electric motor 40, and is transmitted to the yaw axis of the first upper leg link 30R connected to the output shaft of the speed reducer 42. The upper thigh link 30R is rotated relative to the upper body 4. The output shaft of the electric motor 40, the output shaft of the speed reducer 42, and the yaw axis of the first upper leg link 30R are configured to be coaxial.

  An electric motor 44 that drives the hip joint roll shaft portion 12R is disposed on the first upper leg link 30R. The output of the electric motor 44 is transmitted to the speed reducer 48 via the belt 46, and is transmitted to the roll shaft of the second upper leg link 32R connected to the output shaft of the speed reducer 48, so that the second upper leg link 32R is transmitted. Rotate relative to the first upper leg link 30R about the roll axis. The roll axis of the second upper leg link 32R is configured to intersect perpendicularly with the yaw axis of the first upper leg link 30R.

  An electric motor 50 that drives the hip joint pitch shaft portion 14R is disposed above the second upper thigh link 32R. The output of the electric motor 50 is transmitted to the speed reducer 54 via the belt 52, and is transmitted to the pitch axis of the second upper leg link 32R connected to the output shaft of the speed reducer 54, so that the second upper leg link 32R is transmitted. Rotate relative to the first upper leg link 30R about the pitch axis. Note that the pitch axis of the second upper thigh link 32R is configured to intersect perpendicularly with the yaw axis of the first upper thigh link 30R.

  An electric motor 56 that drives the knee joint pitch shaft portion 16R is disposed below the second upper thigh link 32R. The output of the electric motor 56 is transmitted to the speed reducer 60 via the belt 58, and is transmitted to the pitch axis of the crus link 34R connected to the output shaft of the speed reducer 60, so that the crus link 34R is connected to the second upper leg link 32R. Relative to the pitch axis. Note that the pitch axis of the lower leg link 34R is configured to intersect perpendicularly with the yaw axis of the first upper leg link 30R.

  Electric motors 62a and 62b for driving the ankle joint pitch shaft portion 18R and the ankle roll shaft portion 20R are disposed on the crus link 34R. The outputs of the electric motors 62a and 62b are transmitted to the speed reducers 66a and 66b via the belts 64a and 64b, respectively, and input to the input shafts of the crank arms 68a and 68b connected to the output shafts of the speed reducers 66a and 66b, respectively. Communicated. The drive of each crank arm 68a, 68b is transmitted to the connecting pins 72a, 72b provided on the foot 22R via connecting rods 70a, 70b pivotally attached to one ends of the crank arms 68a, 68b, respectively. .

  A pitch shaft 74 is supported at the lower part of the crus link 34, and a roll shaft 76 is supported at the upper part of the foot 22R. The roll shaft 76 is rotatably inserted in the center of the pitch shaft 74 in the roll axis direction. Yes.

  The electric motors 62a and 62b are independently driven, and the rotational driving of the electric motors 62a and 62b is performed by the connecting pins 72a and 72b via the speed reducers 66a and 66b, the crank arms 68a and 68b, and the connecting rods 70a and 70b, respectively. By moving these connecting pins 72a and 72b, the foot 22R is rotated relative to the lower leg link 34R around the pitch axis and the roll axis.

  Specifically, the foot 22R rotates relative to the lower leg link 34R around the pitch axis according to the rotation direction of the crank arms 68a and 68b, and the foot 22R rotates according to the difference in rotation between the crank arms 68a and 68b. The flat 22R rotates relative to the lower leg link 34R around the roll axis. The pitch axis and roll axis of the foot 22R are configured to intersect perpendicularly with the yaw axis of the first upper leg link 30R.

  As shown in FIGS. 4 and 5, the foot 22 </ b> R includes a sole frame 82 formed in a substantially egg shape when viewed from above. A soft plate body such as a sole may be provided on the lower surface of the sole frame 82. A box-shaped housing 84 having an open upper surface is fixed to the upper surface of the substantially central portion of the sole frame 82. Between the bottom plate of the housing 84 and the mounting plate 86 of the six-axis force sensor 36, rubber is provided. A bush 88 made of metal is inserted. Here, bushes 88 are respectively fixed to the bottom surfaces of the four corners of the mounting plate 86 by bolts.

  The six-axis force sensor 36R measures force and moment components in the X-axis direction, the Y-axis direction, and the Z-axis direction, and determines whether the foot 22R has landed (grounded) or the floor reaction force (grounding) acting from the floor surface. Load). The six-axis force sensor 36 </ b> R includes a sensor main body 90 and an external force application plate 92 that is attached to the upper portion of the sensor main body 90 and functions as an external force application unit that applies an external force to the sensor main body 90. The sensor main body 90 is disposed in the recessed portion of the mounting plate 86 and is fixed to the mounting plate 86. A bearing block 94 that supports the roll shaft 76 is fixed to the upper surface of the external force application plate 92 by bolts. In addition to the bearing portion 96 that supports the roll shaft 76, the bearing block 94 is also provided with a bearing portion 98 that supports the connecting pins 72a and 72b.

  Here, when the robot 1 goes straight (moves in the X-axis positive direction), when the leg 2R becomes a support leg, the foot 22R faces the front, that is, a line from the center of the foot 22R toward the toes. L is parallel to the X axis.

  As shown in FIG. 6, the sensor main body 90 is disposed on the foot 22R so that the sensor sensitivity center line in one direction (X-axis direction) of the six-axis force sensor 36R is coaxial with the line L. . On the other hand, the external force application plate 92 is attached to the sensor main body 90 so as to be inclined with respect to the line L outward (Y-axis negative direction) by an angle θ.

  Since it is configured as described above, the first upper leg link 30R, the second upper leg link 32R, and the lower leg link 34R are coupled to the foot 22R via the external force application plate 92. Thereby, when the robot 1 goes straight, when the leg 2R becomes a support leg, the front surface of the first upper leg link 30R, the second upper leg link 32R, and the lower leg link 34R is angled outward from the positive X-axis direction. That is, with reference to FIG. 7, the roll axes of the hip joint roll shaft portion 12R and the ankle joint roll shaft portion 20R (L) are each tilted by an angle θ from the X-axis positive direction, and the hip joint pitch shaft portion. 14R (L), the pitch axes of the knee joint pitch shaft portion 16R (L) and the ankle joint pitch shaft portion 18R (L) are each inclined at an angle θ from the Y axis positive direction to the X axis negative direction.

  Since the robot 1 is configured as described above, it is possible to widen the landing possible range of the free leg. Hereinafter, this will be described. Although the case where the leg 2R is a support leg and the leg 2L is a free leg is described, the same applies to the case where the leg 2L is a support leg and the leg 2R is a free leg.

  When the leg 2R is a support leg, the yaw axis of the hip joint yaw shaft portion 10R is inclined outward from the positive X-axis direction by an angle θ. For this reason, when the knee joint of the leg 2R is bent, the knee portion moves forward and obliquely outward (in the direction from the positive X-axis direction toward the negative Y-axis direction). As shown in FIG. 8, the amount of movement increases as the knee joint angle increases.

  As described above, when the knee joint of the support leg is bent, the knee moves in the outward direction, so that interference between the left and right knees can be suppressed. Therefore, the free leg can be rotated in the direction approaching the support leg, the cornering radius is reduced, and the landing possible range of the free leg is expanded. Accordingly, the degree of freedom of gait increases, and the robot 1 can perform various operations.

  If a joint shaft portion for rotation in the yaw direction is added to the biped mobile robot as disclosed in Patent Document 1, the knee portion of the support leg can be moved outward. However, when the joint shaft portion is added, there is a problem that the configuration becomes complicated and the size and weight increase, and the degree of freedom increases and control becomes difficult. The robot 1 according to the present embodiment, like the legged mobile robot disclosed in the above-mentioned Patent Document 1, each leg 2R, 2L has only 6 degrees of freedom joint shafts, such a problem. Does not occur.

  Furthermore, the above-described effect can be realized by inclining the mounting direction of the external force application plate 92 with respect to the sensor main body 90 by an angle θ. A main part of the leg 2R (L) including the first upper leg link 30R (L), the second upper leg link 32R (L), the lower leg link 34R (L), and the like is attached to the external force application plate 92. Therefore, the above-described effect can be realized without changing the configuration of the main part of the leg 2R (L).

  Further, the sensor sensitivity center line in the X-axis direction of the six-axis force sensor 36R (L) is parallel to the straight traveling direction of the robot 1. Therefore, the 6-axis force sensor 36R (L) can detect each component of the floor reaction force transmitted from the floor to each leg 2R (L) via the foot 22 (L) as in the conventional case. There is no need to convert each detected component.

[Second Embodiment]
Hereinafter, a bipedal mobile robot 1A which is a legged mobile robot according to a second embodiment of the present invention will be described with reference to the drawings. Since the biped mobile robot 1A is similar to the biped mobile robot 1 according to the first embodiment described above, only the differences will be described. Note that the leg 2AR (L) of the biped mobile robot 1A is bilaterally symmetric. Here, the right leg 2AR will be described.

  As shown in FIG. 9, the axis 74A of the ankle joint pitch shaft portion 18AR constituting the ankle joint of the leg 2AR is inclined so that the inner side in the left-right direction (Y-axis direction) is lower than the outer side. Specifically, the axis of the pitch axis 74A of the foot 22AR is inclined by an angle θ from the positive Y-axis direction to the negative Z-axis direction. The pitch shaft 74A is pivotally supported by a pair of spherical plain bearings 77a and 77b attached to the lower part of the lower leg link 34A.

  Since the robot 1A is configured as described above, it is possible to further widen the landing possible range of the free leg as compared to the robot 1. Hereinafter, this will be described. Although the case where the leg 2AR is a support leg and the leg 2AL is a free leg is described, the same applies to the case where the leg 2AL is a support leg and the leg 2RA is a free leg.

  The pitch axis 74A of the foot 22AR of the leg 2AR serving as the support leg is inclined at an angle θ so that the inner side in the left-right direction is lower than the outer side. For this reason, when the knee joint of the leg 2AR is bent, the knee portion moves forward and obliquely outward (in the direction from the X-axis positive direction to the Y-axis negative direction). This movement amount increases as the knee joint angle increases.

  Thus, when the knee joint of the support leg is bent, the knee moves in the outward direction, so that interference between the left and right knees can be further suppressed. Therefore, the free leg can be rotated in the direction approaching the support leg, the cornering radius is reduced, and the landing possible range of the free leg is expanded. Accordingly, compared to the robot 1, the degree of freedom of gait is further increased, the movement stability is increased, and the robot 1A can perform various operations.

  In addition, although embodiment of this invention was described above, this invention is not limited to this. For example, in the embodiment, the case where the sensor sensitivity center line in the X-axis direction of the six-axis force sensor 36R (L) is parallel to the straight traveling direction of the robot 1 or 1A is described, but the present invention is not limited to this. The sensor sensitivity center line of the six-axis force sensor 36R (L) in the X-axis direction may be inclined by an angle θ outward from the positive X-axis direction. However, in this case, it is necessary to convert each component detected by the six-axis force sensor 36R (L).

  In accordance with this, when the robot 1, 1 </ b> A goes straight, the feet 22 </ b> R (L) and 22 </ b> AR (L) of the support legs may be directed outward from the front. However, in this case, since the heels of the feet 22R (L) and 22AR (L) land at the beginning and the toes do not leave at the end, it is necessary to make the sole into the shape of the bottom of the ship.

  Furthermore, as long as the knee joint rotates in the pitch direction, the configuration of each joint and the arrangement of the joint shaft portions are not limited to the embodiment. For example, the joint shaft portion may be configured to have a degree of freedom of 7 degrees of freedom or more and 5 degrees of freedom or less.

  Furthermore, if a leg is bilaterally symmetrical, it will not be limited to a bipedal mobile robot. For example, a 4-legged mobile robot or a 6-legged mobile robot imitating a beast or an insect may be used.

  DESCRIPTION OF SYMBOLS 1,1A ... Biped mobile robot (leg type mobile robot), 2R, 2L, 2AR, 2AL ... Leg, 4 ... Upper body, 10R, 10L ... Hip joint yaw axis (rotating shaft), 12R, 12L ... Hip joint Roll shaft portion, 14R, 14L ... Hip joint pitch shaft portion, 16R, 16L ... Knee joint pitch shaft portion, 18R, 18L, 18AR, 18AL ... Ankle joint pitch shaft portion, 20R, 20L ... Ankle joint roll shaft portion, 22R, 22L , 22AR, 22AL ... foot, 30R, 30L ... first upper thigh link (upper thigh link), 32R, 32L ... second upper thigh link (upper thigh link), 34R, 34L, 34AR, 34AL ... lower thigh link, 36R 36L ... 6-axis force sensor, 74, 74A ... Pitch axis, 90 ... Sensor body, 92 ... External force application plate.

Claims (4)

The upper body, a hip joint that connects the upper body and the upper leg link, a knee joint that connects the upper leg link and the lower leg link, and an ankle joint that connects the lower leg link and the foot, and is bilaterally symmetric A legged mobile robot that moves by driving each leg,
The hip joint has a rotating shaft that rotates in the yaw direction, and when the legged mobile robot goes straight, the upper leg link of the leg serving as a support leg faces obliquely forward and outward with respect to the upper body. In addition, a rotation angle in a yaw direction of the upper thigh link with respect to the upper body is set in the rotation shaft portion.   The legged mobile robot according to claim 1, wherein when the legged mobile robot goes straight, the foot of the leg serving as a support leg faces the front.   6. A six-axis force sensor is provided between the foot and the ankle joint, and a sensitivity center line in one direction of the six-axis force sensor is parallel to a rectilinear direction of the legged mobile robot. Item 3. The legged mobile robot according to item 1 or 2.   The ankle joint has a pitch rotation shaft portion that rotates in the pitch direction, and the axis of the pitch rotation shaft portion is inclined so that the inner side in the left-right direction is lower than the outer side. The legged mobile robot according to item 1.