JP4277671B2 - Walking robot and its foot device - Google Patents

Description

  The present invention relates to a foot device used by being connected to an ankle joint of a walking robot, and a walking robot including the foot device. In the claims and the present specification, the “foot tip” means a portion on the terminal side of the ankle joint.

A robot that walks by changing the relative posture of both legs with respect to the trunk (torso) has been developed (Patent Document 1 discloses an example of this kind of walking robot). Among walking robots of this type, those in which a toe device is composed of a toe front side member and a toe back side member and are connected so as to be swingable have been developed. By using this type of foot device, it is possible to realize a robot that stands on toes. Hereinafter, this type of robot is referred to as a robot having a toe joint.
Japanese Patent Laid-Open No. 3-184781

Just as a human being stands on a toe, the contact surface becomes smaller and the posture becomes unstable. Similarly, a robot having a toe joint has a problem that when a toe stands on the toe, the contact surface becomes smaller and the posture of the robot becomes unstable. Robots with toe joints have faithfully reproduced the structure of humans, and have followed even the weaknesses of humans.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a toe device that can stably support a robot having a toe joint.

The present invention provides a foot tip device that is used by connecting to an ankle joint of a biped robot. The foot tip device of the present invention includes two members that are swingably connected and an actuator that swings the two members. One member is connected to the ankle joint of the biped robot. A ground plane is formed on at least the other member . Swinging axes of the two members noted before, together extend around the front end of the one member in the lateral direction, extends an intermediate position in the longitudinal direction of the other member in the lateral direction. The foot tip device of the present invention is characterized by having the above-described configuration, and third and fourth members may be added.
In this toe device, a toe joint is realized by a swing shaft that swings two members relatively. Even in a posture in which the toes stand, the other member is grounded in a state of extending rearward from the swing shaft, and the grounding is continued on the rear side of the toe joint. It is possible to stand toes at the same time as using the full length of the sole, which cannot be realized by humans, and to maintain a wide contact surface when standing toes. By using this toe device, the biped robot can stand on its toes in a stable state. Alternatively, it is possible to stabilize the robot posture in the ground contact state of the front half of the foot, which is seen when shifting from the ground leg to the free leg.

In the above-described foot device , a ground contact surface is also formed on one member, and the other member is formed in a substantially U shape having a left side, a right side, and a front side connecting the front sides of those sides. The In this case, the left side of the other member extends rearward from the swing shaft on the left side of one member, and the right side of the other member extends rearward from the swing shaft on the right side of the one member.
When configured to enter one of the members to form the other side of the member in a substantially U-shaped recess of the central portion, it is possible to reduce the weight of the toe unit by eliminating the portion that wasteful duplication.

When the toe device of the present invention is used, it is possible not only to continue grounding on the rear side of the toe joint when standing on the toe, but also to detect when the ankle joint is in a state immediately before a grounding load is applied. It becomes.
That is, to the biped walking robot in which the toe device of the present invention is connected to each of the left and right ankle joints, the rear end of the other member of the toe device connected to the ankle joint of the free leg is the other side. A device that controls the actuator so that it is located below the front end of the member and below the connection point of one member to the ankle joint, and the rear end of the other member of each foot tip device If a means for detecting that the ground is touched is added, it becomes possible to detect the time immediately before the ground load is applied to the ankle joint.
In this biped robot, when the ground load is applied to the ankle joint of the free leg, the rear end of the other member of the toe device connected to the ankle joint of the free leg is grounded. Since this ground contact is detected by the detection means, it is possible to detect the time immediately before the ground load is applied to the ankle joint. From the posture of the robot and the posture of the other member at this time, the height of the ground contact surface can be detected before the ground load is applied to the ankle joint of the free leg.

When it is detected that the rear end of the other member of the toe device connected to the ankle joint of the free leg is grounded, it is preferable to reduce the downward moving speed of the ankle joint of the free leg.
If it does in this way, a tip will come to contact | abut slowly and it can prevent that a big grounding impact is applied to a tip.

Here, the main features of the techniques described in the following examples are summarized.
In the following, it is assumed that the traveling direction of the walking robot is the x-axis, the left-right direction is the y-axis, and the height direction is the z-axis.
(Mode 1) The first foot (one member) is connected to the lower leg via an ankle joint. The first foot can swing around the x-axis and swing around the y-axis with respect to the crus by the ankle joint.
(Mode 2) The first foot portion is a substantially quadrangular plate-like member when viewed from above in a grounded state. The second foot portion (the other member) is a substantially U-shaped plate-like member when viewed in plan in a grounded state. In the grounding state, the front surface and the left and right side surfaces of the first foot portion are surrounded by the second foot portion. The lower surface of the first foot is also grounded.
(Embodiment 3) Unlike Embodiment 2, the first foot portion and the second foot portion are substantially rectangular plate-like members when viewed in plan. In this case, the first foot is not grounded.
(Mode 4) The first foot portion and the second foot portion are swung around the toe joint by a motor. A reduction mechanism (for example, a harmonic gear) is connected to the motor.
(Mode 5) An encoder is incorporated in a motor that relatively swings the first foot portion and the second foot portion.

First Embodiment An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a skeleton diagram of a robot 50 according to the present embodiment. Also in this embodiment, the walking direction of the robot 50 is the X axis, the left and right direction of the robot 50 is the Y axis, and the height direction of the robot 50 is the Z axis.
The robot 50 includes a body portion 20 and a left foot 21 and a right foot 22 connected to the body portion 20 by a hip joint. The robot 50 is a biped walking robot.
The left foot 21 includes a left upper thigh 23 connected to the body 20 via the left hip joints 1 and 3, a left lower thigh 25 connected to the left upper thigh 23 via the left knee joint 5, and the left lower thigh The left foot tip portion 27 is connected to the portion 25 via the left ankle joints 7 and 9. The left hip joints 1 and 3 swing around the Y axis and swing around the X axis. The left knee joint 5 swings around the Y axis. The left ankle joints 7 and 9 swing around the Y axis and swing around the X axis.
Similarly, the right foot 22 also has an upper right thigh 24 connected to the body 20 via the right hip joints 2 and 4 and a right lower thigh 26 connected to the upper right thigh 24 via the right knee joint 6. And a right foot tip portion 28 connected to the right lower leg portion 26 via the right ankle joints 8 and 10. The right hip joints 2 and 4 swing around the Y axis and swing around the X axis. The right knee joint 6 swings around the Y axis. The right ankle joints 8 and 10 swing around the Y axis and swing around the X axis.
The left foot tip portion 27 has a first foot portion 27a and a second foot portion 27b. The first foot portion 27a and the second foot portion 27b are relatively swingable with the shaft 11 extending in the y-axis direction (that is, the left-right direction) as a swing axis. Similarly, the right foot portion 28 has a first foot portion 28a and a second foot portion 28b. The first foot portion 28a and the second foot portion 28b can relatively swing about the shaft 12 extending in the y-axis direction as a swing axis. Hereinafter, the shaft 11 and the shaft 12 may be referred to as a toe joint.
The robot 50 includes a motor with an encoder in each of the joints 1 to 12, can adjust the joint angle, and can measure the joint angle.

Next, the structure of the left foot tip portion 27 will be briefly described. Since the right foot tip portion 28 has the same structure as the left foot tip portion 27, description thereof is omitted.
The first foot part 27 a is a substantially rectangular parallelepiped plate-like member, and is connected to the left lower leg part 25 via the shaft 7 and the shaft 9. The first foot 27a can swing around the x-axis and the y-axis with respect to the left lower leg 25.
The second foot portion 27b includes a front portion 100 extending in the left-right direction on the front side of the first foot portion 27a, and a rear portion 102 (right side) extending rearward from both ends of the front portion 100 along the side surface of the first foot portion 27a. ) And the rear portion 104 (left side). The second foot portion 27b includes a front portion 100, a right side 102, and a right side 104, and has a substantially U shape or a substantially U shape when seen in a plan view. The lower surface of the second foot 27b is finished on the same plane, and the entire surface can be grounded. The second foot portion 27b is swingably connected to the first foot portion 27a by a swing shaft 11 extending along the rear edge of the front portion 100. The swing angle of the second foot portion 27b is a motor (in FIG. 1). The reference numeral is omitted, but it can be adjusted by reference numeral 40 in FIG. The front portion 100 of the second foot portion 27b extends to the front side of the swing shaft 11, the right side 102 and the right side 104 extend to the rear side of the swing shaft 11, and the entire second foot portion 27b is the swing shaft. 11 extends in the front-rear direction.
In the state of FIG. 1 (that is, the grounded state), the lower surface of the first foot portion 27a is also grounded. When the first foot portion 27a and the second foot portion 27b are aligned in the same plane, their lower surfaces are adjusted to the same plane, and the entire surface can be grounded.
From the state where the entire lower surfaces of the first foot portion 27a and the second foot portion 27b are in contact with the ground, the first foot portion 27a is swung around the swing shaft 11 so that the first foot portion 27a You can lift the heel side. In other words, the heel side of the first foot portion 27a can be lifted to stand up. Even when the toes stand, the entire lower surface of the second foot 27b continues to be grounded. Even when the toes stand, the ground contact surfaces can be secured on both the front and rear sides of the toe joint 11.

FIG. 2 shows the structure of the left foot tip portion 27 in detail. FIG. 2 is a partial cross-sectional view of the left foot tip portion 27. 3 shows a side view of the left foot tip portion 27 as seen from the direction III in FIG. Here, with reference to FIG.2 and FIG.3, the structure of the left foot tip part 27 is demonstrated in detail.
The first foot portion 27a has a flange 60 that extends forward (X direction in FIG. 2; right direction in the drawing). The flange 60 has a portion 60a extending leftward from the lower side of FIG. 2 and a portion 60b extending leftward from the upper side of FIG. In addition, when FIG. 3 is seen, the part 60a of the flange 60 is understood well.
The motor 40 is fixed to the portion 60 b of the flange 60. The rotating shaft 11 of the motor 40 is connected to the harmonic gear 120.
The harmonic gear 120 includes a wave generator 72, a flex spline 74, and a circular spline 76. Since the harmonic gear 120 is a known speed reduction mechanism, further description is omitted. The circular spline 76 is fixed to the portion 60b of the flange 60 by bolts 78a and 78b. The cylindrical member 80 is also fixed to the portion 60b of the flange 60 by bolts 78a and 78b. That is, the first foot 27a, the flange 60, the circular spline 76, and the member 80 are assembled.
The flex spline 74 of the harmonic gear 120 is fixed to a disk-shaped member 82. The member 82 is fixed to the member 84. The member 84 is rotatably supported by a member 80 that is an assembly through a bearing 86. The member 84 is fixed to a flange 88 provided on the second foot portion 27b.
A portion 60 a of the flange 60 is fixed to a cylindrical member 64 by a bolt 62. A bearing 66 is inserted between the flange 68 provided on the second foot portion 27b and the member 64 described above.
When the rotating shaft 11 is rotated in a predetermined direction, the first foot portion 27a swings with respect to the second foot portion 27b at a speed reduced from the rotational speed. That is, the heel side of the first foot portion 27a floats and stands on the toe.

The robot 50 has an actuator for driving each joint 1 to 12. For example, the motor 40 described above is provided corresponding to the joint 11. The robot 50 includes a control device 200 that drives and controls each actuator. The configuration of the control system of the robot 50 will be described with reference to FIG. FIG. 4 is a block diagram showing the control system of the robot 50 in a very simplified manner.
The control device 200 is connected to the gait data storage device 202. Here, the gait data will be described. The gait data indicates the positions of the trunk 20 (torso) and the toes 27 and 28 in a global coordinate system that defines the coordinates of the space in which the robot 50 is active. In order to indicate the positions of the trunk 20 and both toes 27 and 28, reference points are defined on the trunk 20, the left toe 27 and the right toe 28, respectively. The gait data includes coordinate data (x, y, z) in the global coordinate system that indicates the position of the reference point of the trunk 20, the reference point of the left foot tip 27, and the reference point of the right foot tip 28 over time. ing. The coordinate data of (x, y, z) changes with respect to the elapsed time t from the start of the operation of the robot 50. By changing the relative postures of the trunk 20 and both feet 21 and 22 over time according to the gait data indicating the positions of the trunk 20, the left toe 27, and the right toe 28 that change over time, the robot 50 Walk.
The gait data storage device 202 stores gait data that indicates the positions of the trunk 20, the left toe 27, and the right toe 28 that change over time.

The control device 200 calculates the joint angles of the joints 1 to 12 necessary for realizing the posture according to the gait data stored in the gait data storage device 202, and rotates the joints 1 to 12. To adjust the calculated joint angle. Thereby, each joint angle calculated according to the gait data which changes with time changes with time. As the control device 200 changes the joint angle over time, the relative positional relationship between the trunk 20 and both feet 27 and 28 changes over time, and as a result, the robot 50 walks.
A more detailed explanation for controlling the robot 50 according to the gait data is described in Japanese Patent Application No. 2003-354866 already filed by the present applicant.

Next, how the joints 11 and 12 are adjusted in the process of walking the robot 50 will be described. In the control device 200, the rear end of the second foot portion 27b (28b) of the foot portion 27 (28) of the free leg is located below the front end, and the rear end of the first foot portion 27a. A program (hereinafter referred to as a swing leg program) for maintaining a state of being lower (or coincident) is set.
With reference to FIG. 5, how the joint 11 is controlled by the above-described swing leg program will be described. FIG. 5 shows the posture of the left foot tip portion 27 in time series when the joint 11 is controlled by the free leg program.
FIG. 5A illustrates the left foot tip portion 27 that is completely in contact with the ground G. In this case, both the first foot portion 27a and the second foot portion 27b are grounded.
From the state of FIG. 5A, the control device 200 swings the heel side of the grounded first foot portion 27a upward with respect to the second foot portion 28a. In other words, the toes stand. This is done by controlling the motor 40 so that torque is applied in the direction of standing toes. FIG. 5B shows the toe 27 when standing on the toes.
Subsequently, the control device 200 lifts the left foot tip portion 27. That is, the left foot 21 is a free leg. This is done by adjusting the joint angles of each joint 1-10. FIG. 5C illustrates the free leg foot 27. In this case, the rear end of the second foot portion 27b is located below the front end and located below the rear end of the first foot portion 27a (of course, than the ankle joints 7 and 9). Located below). While the left foot 21 is a free leg, the posture of FIG. 5C is maintained (the angle α between the first foot portion 27a and the second foot portion 28b is maintained).
FIG. 5 (d) shows a moment when the left foot tip portion 27 of the free leg contacts the ground. Since the rear end of the second foot 27b is located below the first foot 27a, the rear end of the second foot 27b is first grounded. When the left foot portion 27 further moves downward from the state shown in FIG. 5D, the second foot portion 27b is gradually grounded and finally completely grounded as shown in FIG. 5A. The control performed by the control device 200 after the free leg starts to be grounded until it is completely grounded will be described later.

The swinging angle α (shown in FIG. 5 (c)) between the first foot 27a (28a) and the second foot 27b (28b) of the free leg is the angle until contact with the ground. Is maintained. When the second foot 27b (28b) comes into contact with the ground, the swing angle α decreases.
The encoder 211 (212) shown in FIG. 4 outputs the swing angle between the first foot 27a (28a) and the second foot 27b (28b) to the control device 200. The control device 200 can detect that the free leg has started to contact ground by monitoring that the swing angle of the free leg output from the encoder 211 (212) is smaller than α. The control device 200 controls the actuators that drive the joints 1 to 12 so that the swing angle of the free leg gradually decreases when the free leg starts to contact the ground. Specifically, when the rear end of the second leg portion 27b (28b) of the free leg contacts the joint 1 so that the speed of moving the ankle joint of the free leg downward is lower than before the ground contact. The actuator that drives -12 is controlled (this control will be referred to as ground control). By doing so, the free leg can be grounded slowly. This grounding control is performed until the swing angle of the first foot portion 27a (28a) and the second foot portion 27b (28b) of the toe portion 27 (28) of the free leg becomes smaller than α and becomes zero. (Ie until fully grounded).

FIG. 6 illustrates a change with time in the z direction (height direction) of the ankle joints 7 and 9 of the left foot tip portion 27. A state is shown in which the left foot 21 is raised from the reference height (shown by a broken line) (the left foot 21 is a free leg) and the left foot 21 of the free leg is grounded. In the figure, t1 and t2 are times when the second foot 27b starts to be grounded (state of FIG. 5D), and t1 ′ and t2 ′ are completely grounded (FIG. 5A). It shows the time when
From t1 to t1 ′ and t2 to t2 ′ in FIG. 6, it can be seen that the change in the height of the left toe portion 27 is gentle. This is because, after the rear end of the second foot portion 27b is grounded, the ground control is performed so that the left foot tip portion 27 is grounded slowly.
At t2, the grounding is performed at a position higher than the grounding height at t1. Even in this case, the ground control is performed after t2. The time between t1 and t1 ′ and the time between t2 and t2 ′ are the same. In the present embodiment, even if the walking surface height of the robot 50 changes, it can be detected that the rear end of the second foot portion 27b (28b) is grounded, so that the ground control can be performed accurately. .

According to the above embodiment, the toe joint 11 (12) is realized by relatively swinging the two foot portions 27a (28a) and 27b (28b). The second foot 27b (28b) extends across the shaft 11 (12) in the grounded state. A ground plane is widely secured. Even if the first foot 27a (28a) is swung to make the robot 50 stand on the toes, the robot 50 can continue to stand in a stable state.
In the walking robot 50, when the free leg is grounded, the rear end of the second foot 27b (28b) is first grounded. The joint 11 (12) is provided with an encoder. For this reason, it can be detected that the free leg has started to contact the ground. The walking robot can detect the height of the walking surface before the toes are completely grounded. And when a free leg begins to ground, in order to make the free leg ground slowly, it can prevent that a big impact is applied to the foot tip part 27 (28).

( Reference example)
Here, a description will be given with the reference example. This reference example is different from the first embodiment in the structure of the first toe portion and the second toe portion. FIG. 7 simply shows a side view (a) and a plan view (b) of the left foot tip portion 327 of the reference example.
The first toe portion 327a and the second toe portion 327b of the reference example are both substantially rectangular parallelepiped shapes. The first toe portion 327a and the second toe portion 327b can swing relatively with a shaft 311 extending in the y direction as a fulcrum.
Even if the toe portion 327 as in this reference example is used, the same effect as in the first embodiment can be obtained.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, you may make it drive the toe joints 11 and 12 in an above-described Example via a pulley. An actuator other than a motor may be used.
In the above-described embodiment, it is detected that grounding has started by monitoring the output of the encoder, but it may be detected using other methods. For example, a contact sensor may be provided on the ground plane. Moreover, you may make it detect using a force sensor and a torque sensor.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

A skeleton diagram of the robot is shown. A partial sectional view of a foot tip part is shown. The foot tip part seen from the III line of FIG. 2 is shown. The configuration of the robot control system is shown briefly. A time series from the state in which the toe portion is in contact to the start of contact with the free leg is shown. The time-dependent change of the height of a foot part is shown. The side view and top view of the foot part of a reference example are simply shown.

Explanation of symbols

1-12: Axis 21: Left foot 22: Right foot 23, 24: Upper thigh 25, 26: Lower thigh 27, 28: Toe 27a: First foot 27b: Second foot 40: Motor 50 : Robot 150: Front end 152 of the first foot part: Rear end 200 of the center part of the second foot part 200: Control device

Claims (3)

It is a toe device used by connecting to the ankle joint of a biped walking robot,
Two members connected to be swingable, and an actuator for swinging the two members;
One member is connected to the ankle joint of a biped robot,
A ground plane is formed on at least the other member,
The swing shafts of the two members extend in the left-right direction near the front end of the one member, and extend in the left-right direction at an intermediate position in the front-rear direction of the other member .
The other member has a substantially U shape having a left side, a right side, and a front side connecting the front sides thereof, and the left side and the right side extend rearward from the swinging shaft on the left side and the right side of the one member. And
A ground plane is formed on each of the left side, right side, and front side of the other member,
A grounding surface is also formed on the one member,
In a state where both the one member and the other member are grounded, the left side of the other member extends rearwardly beyond the front end of the one member on the left side of the one member, The toe device characterized in that the right side of the member extends rearward on the right side of the one member beyond the front end of the one member . A biped walking robot in which the toe device of claim 1 is connected to each of the left and right ankle joints,
The rear end of the other member of the ankle device connected to the ankle joint of the free leg is positioned below the front end of the other member, and the connection point of the one member to the ankle joint is A device for controlling the actuator so that the
Means for detecting that the rear end of the other member of each foot tip device is grounded is added. The downward movement speed of the ankle joint of the free leg is reduced when it is detected that the rear end of the other member of the toe device connected to the ankle joint of the free leg is grounded. Two biped robots.

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