Joint structure and humanoid robot

Abstract

To provide a joint structure and a humanoid robot having relatively small torque when moving a simulated foot flat with respect to a simulated lower leg.SOLUTION: The joint structure 1 includes a simulated lower leg 3, a simulated foot 5 having a sole surface 6 facing the ground or a floor surface in a standing position, and a simulated joint 9 connected to the simulated lower leg 3 so as to move the simulated foot 5. The simulated foot 5 is formed with a recessed part 8 recessed toward the sole surface 6 from the opposite side of the sole surface 6, and at least a part of the simulated joint 9 is arranged inside the recessed part 8. The humanoid robot includes two joint structures 1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an articulated structure and a humanoid robot. [Background technology]

[0002] Patent Document 1 discloses a joint structure used in a bipedal robot. This joint structure includes an ankle joint that connects the lower leg and the foot so that they can rotate freely relative to each other, and the ankle joint includes a pitch joint structure having a pitch axis shaft that rotates about a pitch axis and a roll joint structure having a roll axis shaft that rotates about a roll axis. The pitch axis shaft and the roll axis shaft intersect, and the entire pitch joint structure and roll joint structure are located above the foot. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-15119 Summary of the Invention [Problem to be solved by the invention]

[0004] In the joint structure described in Patent Document 1, the entire pitch joint structure and roll joint structure are located above the foot, which allows for a relatively simple design requiring minimal processing man-hours. However, the distance from the ground to the shaft is long, which tends to increase the torque required to move the foot.

[0005] In view of the above-mentioned problems, the present disclosure relates to providing a joint structure and a humanoid robot that can reduce the torque required to move a simulated foot relative to a simulated lower leg. [Means for solving the problem]

[0006] The joint structure of the present disclosure is a joint structure for a humanoid robot, and comprises a simulated lower leg, a simulated sole of the foot that faces the ground or floor surface when standing, and a simulated joint that movably connects the simulated sole of the foot to the simulated lower leg, wherein the simulated sole of the foot has a recess formed therein that is recessed from the opposite side of the sole of the foot toward the sole of the foot, and at least a portion of the simulated joint is positioned inside the recess.

[0007] The humanoid robot according to the present disclosure includes two of the above-described joint structures. [Effects of the Invention]

[0008] According to the present disclosure, at least a portion of the simulated joint is positioned inside the recess, so that the simulated joint is positioned close to the sole of the foot, thereby reducing the torque required to move the simulated sole of the foot relative to the simulated lower leg. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view showing a schematic configuration of a humanoid robot according to a second embodiment of the present disclosure, including a joint structure according to a first embodiment of the present disclosure. [Figure 2] 1A is a partial cross-sectional side view of a joint structure according to a first embodiment of the present disclosure, and FIG. 1B is a partial cross-sectional front view of the joint structure. [Figure 3] FIG. 10 is a partial perspective view of a joint structure according to a modified example of the first embodiment of the present disclosure. [Figure 4] FIG. 1A is a schematic diagram showing a first modified example of the simulated joint, FIG. 1B is a schematic diagram showing a second modified example, and FIG. 1C is a schematic diagram showing a third modified example. [Figure 5] FIG. 10 is a schematic diagram showing the configuration of a fourth modified example of the simulated joint. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, identical or similar reference numerals are used to designate identical or corresponding components, and redundant explanations will be omitted. Furthermore, the dimensions and proportions of the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0011] <Representative example of embodiment> FIG. 1 is a front view showing a schematic configuration of a humanoid robot 100 according to a second embodiment of the present disclosure, including the joint structure 1 according to the first embodiment of the present disclosure. The front view of FIG. 1 shows the humanoid robot 100 in a standing position. The joint structure 1 constitutes the portion of the lower limb of the humanoid robot 100 below the knee. The humanoid robot 100 is equipped with two joint structures 1. These two joint structures 1 correspond to the two legs of a human being. Details of the joint structure 1 will be described below.

[0012] Fig. 2(A) is a partial cross-sectional side view of the joint structure 1, and Fig. 2(B) is a partial cross-sectional front view of the joint structure 1. In Fig. 2(A), the left side of the paper is the front side (or front side) of the humanoid robot 100 (see Fig. 1), and the right side of the paper is the back side (or rear side). The joint structure 1 comprises a simulated lower leg 3, a simulated foot 5, and a simulated joint 9. Figs. 2(A) and 2(B) illustrate the configuration of the simulated joint 9 so that it is easy to understand, and the upper part of the simulated lower leg 3 is omitted. The simulated joint 9 is a component that connects the simulated lower leg 3 and the simulated foot 5.

[0013] The simulated lower leg 3 simulates a human lower leg, that is, the part from the knee to the ankle. The simulated lower leg 3 may be formed in the shape of a hollow cylinder or a half pipe to reduce weight, or in the shape of a solid rod to increase rigidity. The simulated lower leg 3 is typically made of a synthetic resin such as carbon fiber reinforced plastic (CFRP), but may also be made of metal or other materials, taking into consideration the environment, such as the location and application of the humanoid robot 100 (see FIG. 1).

[0014] The simulated foot 5 simulates the portion of a human foot below the ankle. In this embodiment, the simulated foot 5 has a rectangular, thick, planar shape (i.e., a thick plate-like shape) when viewed from above. The simulated foot 5 is used with both longitudinal ends of the rectangle positioned at the front and rear. In the simulated foot 5 shown in FIG. 2(A), the left side of the paper corresponds to the toe portion (or front side), and the right side of the paper corresponds to the heel portion (or rear side). The simulated foot 5 has a thick, planar first surface that serves as the sole 6 that faces or comes into contact with the ground or floor when the humanoid robot 100 (see FIG. 1) is in a standing position. The simulated foot 5 has a second surface, the upper surface 7, opposite the sole 6, that has a recess 8 recessed toward the sole 6. The recess 8 is a recess for accommodating at least a portion of the simulated joint 9. The recessed portion 8 may be formed by cutting out a thick plate-like member, or by providing a sidewall member around a relatively thin plate-like member, one surface of which corresponds to the sole surface 6. The shape and / or size of the recessed portion 8 may be determined taking into consideration the rigidity of the simulated foot 5 and ease of processing. For example, the shape of the recessed portion 8 may be formed as a rectangular parallelepiped as shown in FIGS. 2(A) and 2(B) from the perspective of ease of processing, or may be formed as a curved surface (or a sphere or ellipsoid) from the perspective of suppressing a decrease in the rigidity of the simulated foot 5. The simulated foot 5 is typically formed from a synthetic resin such as CFRP, but may also be formed from metal or other materials taking into consideration the environment, such as the location and purpose of use of the humanoid robot 100 (see FIG. 1).

[0015] The simulated joint 9 connects the simulated foot 5 to the simulated lower leg 3 so that it can move. The simulated joint 9 simulates a human ankle joint. Therefore, the simulated joint 9 connects the simulated foot 5 to the simulated lower leg 3 so that it can rotate about one axis or multiple axes. The operating principle of the simulated joint 9 can be, for example, rotation or various link mechanisms. In this embodiment, the simulated joint 9 includes a first simulated joint 10 (hereinafter simply referred to as the "first joint 10") and a second simulated joint 20 (hereinafter simply referred to as the "second joint 20"). The first joint 10 can move about a first rotation axis 12 (hereinafter simply referred to as the "first axis 12"). The second joint 20 can move about a second rotation axis 22 (hereinafter simply referred to as the "second axis 22"). In this embodiment, the simulated joint 9 is configured such that the first joint 10 and the second joint 20 are interlocked with each other in a state in which the first axis 12 and the second axis 22 are orthogonal in plan view. With this configuration, the simulated lower leg 3 and the simulated foot 5, which are connected via the simulated joint 9, can move relatively in three-dimensional space.

[0016] In this embodiment, the first joint 10 has a first shaft 11, two bearings 13, and a support member 14. The first shaft 11 is typically a round bar-shaped (or cylindrical) member and is arranged to extend in the longitudinal direction of the simulated foot 5. A first end of the first shaft 11 is connected to the second joint 20. The first shaft 11 is supported by one of the bearings 13 so as to be rotatable about its axis. The axis of the first shaft 11 coincides with the first axis 12. Therefore, the first shaft 11 can rotate about the first axis 12. The support member 14 is a member that cooperates with the first shaft 11 to support the second joint 20 from the opposite side of the first shaft 11. The support member 14 is typically formed of a round bar-shaped member similar to the first shaft 11. The support member 14 is rotatably supported by another bearing 13 with its axis positioned on the same imaginary straight line as the first axis 12. The bearing 13 supporting the first shaft 11 and the bearing 13 supporting the support member 14 are each attached to the upper surface 7 of the simulated foot 5. The two bearings 13 are spaced apart in the longitudinal direction of the simulated foot 5 and attached to the upper surface 7 across the recessed portion 8.

[0017] In the present embodiment, the first joint 10 is provided with a motor 17 and a reducer 18 on the first axis 12. The motor 17 is typically an electric motor that inputs electrical energy and outputs mechanical work. The motor 17 can rotate its output shaft in either forward or reverse direction depending on the situation. The motor 17 may be a stepping motor or a servo motor. The reducer 18 is a device that reduces the rotational speed of the output shaft of the motor 17. The reducer 18 is typically configured to reduce the rotational speed of the output shaft of the motor 17 to a desired rotational speed using multiple gears. The reducer 18 may be a harmonic reducer. The motor 17 and the reducer 18 together constitute a first actuator 16. In the present embodiment, the first joint 10 and the first actuator 16 are integrally arranged. In the present embodiment, the output shaft of the first actuator 16 is directly connected to the second end of the first shaft 11. With this configuration, the first joint 10 allows the first shaft 11 to rotate forward and backward around the first axis 12 by the output of the motor 17. For convenience of explanation, the output shaft of the first actuator 16 and the first shaft 11 are configured separately, but the output shaft of the first actuator 16 may have a desired length and serve as the first shaft 11.

[0018] In this embodiment, the second joint 20 has a second shaft 21, a bearing 23, and a case 24. The second shaft 21 is typically a round bar-shaped (or cylindrical) member and is disposed so as to extend in a direction perpendicular to the longitudinal direction of the simulated foot 5. The second shaft 21 penetrates the side surface of the cylindrical simulated foot 3, which is closer to the simulated foot 5. The second shaft 21 is rotatably supported by a bearing 23 on one outer side of the side surface of the simulated lower leg 3 through which it penetrates. The axis of the second shaft 21 coincides with the second axis 22. Therefore, the second shaft 21 can rotate about the second axis 22. In this embodiment, the second axis 22 and the first axis 12 exist on the same imaginary plane. The bearing 23 is attached to the side surface of the simulated lower leg 3. Typically, a portion of the case 24 is embedded inside the simulated lower leg 3. The case 24 covers the second shaft 21 inside the simulated lower leg 3. The case 24 is a member formed in a cylindrical shape and is disposed with the cylindrical axis coinciding with the second axis 22. The case 24 is fixed to the second shaft 21. As shown in FIG. 2(A) , the first end of the first shaft 11 and the support member 14 are connected to the cylindrical side surface of the case 24. In other words, in this embodiment, the second joint 20 is supported at both ends by the first shaft 11 and the support member 14 via the case 24. In this way, the case 24 is a member of the second joint 20 to which the first joint 10 is connected.

[0019] In the present embodiment, the second joint 20 is provided with a motor 27 and a reducer 28 on the second axis 22. The motor 27 has a configuration similar to that of the motor 17 of the first joint 10. The reducer 28 has a configuration similar to that of the reducer 18 of the first joint 10. In the present embodiment, the casing of the motor 27 is fixed to the side of the simulated lower leg 3 outside the case 24, and the reducer 28 is disposed inside the case 24. The motor 27 and the reducer 28 together constitute a second actuator 26. In the present embodiment, the output shaft of the second actuator 26 is directly connected to the end of the second shaft 21. That is, in the present embodiment, the second shaft 21 is supported at both ends by the bearing 23 and the second actuator 26. With this configuration, the second joint 20 allows the second shaft 21 to rotate forward and backward around the second axis 22 by the output of the motor 27. For ease of explanation, the output shaft of the second actuator 26 and the second shaft 21 are described as being separate structures, but the output shaft of the second actuator 26 may have a desired length and serve as the second shaft 21 as well.

[0020] The simulated joint 9, including the first joint 10 and second joint 20 described above, can rotate the simulated foot 5 in both directions relative to the simulated lower leg 3 about a first axis 12 by actuation of the first actuator 16. This rotational movement in both directions about the first axis 12 results in the simulated foot 5 supinating and pronating (a so-called roll movement), so the first axis 12 can be seen as a roll axis. Furthermore, the simulated joint 9 can rotate the simulated foot 5 in both directions relative to the simulated lower leg 3 about a second axis 22 by actuation of the second actuator 26. This rotational movement in both directions about the second axis 22 results in the simulated foot 5 dorsiflexing and plantarflexing (a so-called pitch movement), so the second axis 22 can be seen as a pitch axis.

[0021] In this embodiment, the joint structure 1 has a portion of the second joint 20 disposed inside the recessed portion 8 of the simulated foot 5. Here, the inside of the recessed portion 8 refers to the space on the sole 6 side of the hypothetical upper surface 7, assuming that there is also an upper surface 7 above the recessed portion 8 if the upper surface 7 is flat (this will be referred to as the "hypothetical upper surface"). From another perspective, disposing a portion of the second joint 20 inside the recessed portion 8 can be said to be sized and positioned so that a portion of the second joint 20 can be disposed inside the recessed portion 8. In the joint structure 1, the simulated foot 5 moves relative to the simulated lower leg 3 about the first axis 12 and the second axis 22, so it is preferable that the recessed portion 8 be sized and positioned so that the simulated lower leg 3 does not interfere with the simulated foot 5 due to such movement. Here, "the simulated lower leg 3 does not interfere with the simulated foot 5" typically means that the two do not come into contact due to such movement. The recessed portion 8 is formed to a size and position that prevents the simulated lower leg 3 from interfering with the simulated foot 5, thereby increasing the range of motion of the simulated foot 5 relative to the simulated lower leg 3.

[0022] In the joint structure 1, a portion of the second joint 20 is disposed inside the recess 8 of the simulated foot 5, so that the simulated joint 9 is disposed close to the sole surface 6, and therefore the first axis 12 and the second axis 22 are disposed close to the simulated foot 5. This configuration reduces the torque required to rotate the simulated foot 5 about the first axis 12 and the second axis 22 relative to the simulated lower leg 3. Reducing the torque required to rotate the first shaft 11 and the second shaft 21 allows the motor 17 and the reducer 18, as well as the motor 27 and the reducer 28, to be made smaller, thereby reducing the weight of the simulated joint 9 and increasing its range of motion. Reducing the weight of the simulated joint 9 reduces the inertial force of the movement of the joint structure 1, allowing the simulated foot 5 to move more quickly relative to the simulated lower leg 3, thereby improving the athletic performance of the joint structure 1. In this embodiment, no part of the first joint 10 is disposed inside the recessed portion 8, but the first axis 12 is disposed on the same plane as the second axis 22, so that when the second axis 22 approaches the sole surface 6, the first axis 12 also approaches the sole surface 6. In this way, from the viewpoint of reducing the rotational torque of the first shaft 11 and miniaturizing the motor 17 and the reducer 18, it is preferable to dispose the first axis 12 as close to the simulated foot 5 as possible.

[0023] The humanoid robot 100 including the above-described joint structure 1 can perform various movements that mimic human movements, including walking, by appropriately moving the parts corresponding to each joint. The joint structure 1 allows the simulated foot 5 to rotate back and forth about the first axis 12 and the second axis 22 relative to the simulated lower leg 3, enabling timely roll and pitch movements. This allows the humanoid robot 100 including the joint structure 1 to walk while adapting to unsteady environments, such as uneven terrain. By moving the second axis 22 and the first axis 12 closer to the simulated foot 5, the weight of the first actuator 16 and the second actuator 26 can be reduced, reducing the weight of the joint structure 1 and the inertial force, enabling faster walking. Thus, the inclusion of the joint structure 1 improves the movement performance of the humanoid robot 100.

[0024] As described above, in the joint structure 1 according to this embodiment, a portion of the second joint 20 is disposed inside the recessed portion 8, so that the second axis 22 and the first axis 12 intersecting therewith can be brought closer to the simulated foot 5, thereby reducing the torque required for rotation. Furthermore, because the first axis 12 and the second axis 22 are orthogonal to each other and exist on the same imaginary plane, the simulated foot 5 can move appropriately in three-dimensional space with a relatively small torque relative to the simulated lower leg 3. Furthermore, because the torque required to move the simulated foot 5 with respect to the simulated lower leg 3 is relatively small, the first actuator 16 and the second actuator 26 can be made smaller. Furthermore, because the first actuator 16 is disposed on the same axis as the first axis 12, the clearance structure for arranging the motor 17 (for example, a structure in which the simulated lower leg 3 is notched) can be made smaller. Therefore, if the amount of movement (or the angle of movement) of the simulated foot 5 with respect to the simulated lower leg 3 is the same, the rigidity of a member with a smaller clearance structure can be increased, and if the rigidity is the same, the amount of movement (or the angle of movement) can be increased. The same applies to the second actuator 26. Furthermore, the recessed portion 8 is formed to a size and position that prevents interference between the simulated lower leg 3 and the simulated foot 5 when the simulated foot 5 moves about the first axis 12 and the second axis 22 relative to the simulated lower leg 3, thereby increasing the range of motion of the simulated foot 5 relative to the simulated lower leg 3.

[0025] <Modification> Next, with reference to FIG. 3, an articulated structure 1A according to a modified example of the first embodiment of the present disclosure will be described. FIG. 3 is a partial perspective view of the articulated structure 1A. The articulated structure 1A has a simulated foot 5A in which a recess 8 penetrates the sole 6, forming a through-hole 8A. The formation of the through-hole 8A in the simulated foot 5A allows the ground or floor surface facing the sole 6 to be seen when viewing the sole 6 from the top surface 7 side. The formation of the through-hole 8A in the recess 8 of the simulated foot 5A in the articulated structure 1A allows the simulated joint 9 (e.g., the second joint 20) located inside the recess 8 to be closer to the ground or floor surface. This allows the second axis 22 to be closer to the sole 6, further reducing the torque required by the second actuator 26 to rotate the second shaft 21. If the first axis 12 could also be closer to the sole 6, the torque required by the first actuator 16 to rotate the first shaft 11 could be further reduced. In the example shown in Figure 3, the entire recess 8 penetrates the sole of the foot 6, but it is also possible for a portion of the recess 8 to penetrate the sole of the foot 6 so that a penetration portion 8A is provided in the recess 8 at a portion where the simulated lower leg 3 may interfere.

[0026] The joint structure 1A shown in FIG. 3 is also provided with force sensors 51 attached to the sole 6. The force sensors 51 detect the load acting on the sole 6 when the simulated foot 5A comes into contact with the ground or floor while attached to the sole 6, and are sometimes referred to as force sensors. The provision of the force sensors 51 makes it possible to detect the force acting when the simulated foot 5A comes into contact with the ground or floor, which contributes to the analysis of the motion of the joint structure 1A. In this modified example, a total of three force sensors 51 are provided: two on the sole 6 of the toe portion and one on the sole 6 of the heel portion (not shown in FIG. 3). The two force sensors 51 attached to the sole 6 of the toe portion are spaced apart in a direction intersecting the longitudinal direction of the simulated foot 5A (typically a direction perpendicular to the longitudinal direction), and are typically located at each of the two corners of the toe portion of the simulated foot 5A. One force sensor (not shown) attached to the sole 6 of the heel is typically located midway between the two corners of the heel of the simulated foot 5. This arrangement of the force sensors 51 allows the minimum number of force sensors 51 to grasp not only the load applied when the humanoid robot 100 is walking, but also the force distribution when the joint structure 1A stands on its tiptoes due to a pitch motion or tilts laterally due to a roll motion. The force sensors 51 can be any one of 1- to 6-axis sensors depending on the purpose and location. The number and location of the force sensors 51 are not limited to the above example and can be changed as appropriate depending on the requirements and uses of the joint structure 1A. For example, instead of providing a force sensor 51 in the toe area, a 6-axis force sensor can be installed in the area corresponding to the ankle to simulate the force acting on the toe area. Of course, a 6-axis force sensor may also be used as the force sensor 51 attached to the sole 6.

[0027] 3, the sole 6 at the portion where the force sensor 51 is attached is recessed (or curved) toward the opposite side of the sole 6, i.e., toward the top surface 7. In this modification, the sole 6 at the toe and heel portions of the simulated foot 5A is recessed toward the top surface 7. In other words, when each force sensor 51 is in contact with the ground or floor, the sole 6 at the toe and heel portions is away from the ground or floor, and the sole 6 between the toe and heel portions is closer to the ground or floor. When the top surface 7 is not flat in this way, the recess 8 is defined as a space formed on the top surface 7 toward the sole 6 from an imaginary plane where the highest point on the front end side (or toe side) and the highest point on the rear end side (or heel side) meet. If the part of the sole 6 where the force sensor 51 is attached is set back toward the top surface 7, when the force sensor 51 is attached to that location, the simulated joint 9 (the second joint 20 in this modification), at least a part of which is located inside the recessed portion 8, can be positioned closer to the ground or floor surface. This makes it possible to stabilize the movement of the joint structure 1A.

[0028] The joint structure 1A shown in FIG. 3 has three main features that are different from the joint structure 1 (see FIGS. 2(A) and 2(B)): the "through-hole 8A," the "force sensor 51," and the "retraction of the sole 6 at the portion where the force sensor 51 is attached." These three features do not have to be applied simultaneously, and can be applied singly or in any combination of multiple features. For example, a modified version of the joint structure 1 (see FIGS. 2(A) and 2(B)) may be applied with only the through-hole 8A, or a modified version may be applied with two features, the force sensor 51 and the retraction of the sole 6.

[0029] <Other> In the above description, the second joint 20 is supported at both ends by the first shaft 11 and the support member 14. However, the support member 14 and the single bearing 13 supporting it may not be provided (omitted), and the second joint 20 may be supported at one end by the first shaft 11. In this case, a cross roller bearing may be used for the bearing 13 of the first shaft 11. Furthermore, although the second shaft 21 is supported at both ends by the bearing 23 and the second actuator 26, the second shaft 21 may be supported at one end by the second actuator 26 without providing (omitting) the bearing 23.

[0030] In the above explanation, the first joint 10 and the second joint are related in a state where the first axis 12 and the second axis 22 are perpendicular to each other in a plan view. However, the first axis 12 and the second axis 22 may be arranged so that they intersect at an angle other than a right angle. By making the first axis 12 and the second axis 22 intersect at an angle other than a right angle, the two joint structures 1 of the humanoid robot 100 can be constructed in a bow-legged or knock-kneed style.

[0031] In the above description, the first axis 12 and the second axis 22 are assumed to exist on the same imaginary plane. However, depending on the application of the joint structure 1 and the required performance, the first axis 12 and the second axis 22 may be arranged to exist on different imaginary planes.

[0032] In the above explanation, a portion of the second joint 20 is disposed inside the recessed portion 8 of the simulated foot 5, and no portion of the first joint 10 is disposed inside the recessed portion 8. However, not only at least a portion of the second joint 20 but also at least a portion of the first joint 10 may be disposed inside the recessed portion 8.

[0033] In the above description, the simulated joint 9 includes the first joint 10 and the second joint 20, but it may be configured with either the first joint 10 or the second joint 20 depending on the functions required of the humanoid robot 100. In other words, the simulated joint 9 may be configured to be able to rotate either around the first axis 12 or around the second axis 22. Alternatively, the simulated joint 9 may include three or more joints (i.e., three or more mechanisms that rotate around rotation axes).

[0034] In the above description, the first actuator 16 has the motor 17 and the reducer 18. However, if the first actuator 16 can be used without changing the rotation speed of the output shaft of the motor 17 and there is no need to reduce the rotation speed, the reducer 18 does not have to be provided (can be omitted). Similarly, the second actuator 26 has the motor 27 and the reducer 28, but if the first actuator 16 can be used without changing the rotation speed of the output shaft of the motor 27 and there is no need to reduce the rotation speed, the reducer 28 does not have to be provided (can be omitted).

[0035] In the above description, the motor 17 and the reducer 18 in the first actuator 16 are provided on the first axis 12 (i.e., on the same axis as the first axis 12), but they may be provided at a position away from the first axis 12. Similarly, in the second actuator 26, the motor 27 and the reducer 28 are provided on the second axis 22 (i.e., on the same axis as the second axis 22), but they may be provided at a position away from the second axis 22.

[0036] 4(A), a second joint 20A may be constructed in which a gear 25A is attached to the second shaft 21, a second actuator 26 may be provided at a position away from the second shaft 21, and the second actuator 26 and the gear 25A may be meshed and joined together. In the second joint 20A, the rotational motion of the second actuator 26 is transmitted to the second shaft 21 via the gear 25A.

[0037] 4(B), a second joint 20B may be constructed in which a pulley 25B is attached to the second shaft 21, a second actuator 26 may be provided at a position away from the second shaft 21, and the second actuator 26 and the pulley 25B may be connected by a belt 125B. In the second joint 20B, the rotational motion of the second actuator 26 is transmitted to the second shaft 21 via the belt 125B and the pulley 25B.

[0038] 4(C), a second joint 20C may be constructed in which a crank disk 25C is attached to the second shaft 21, a second actuator 26 may be provided at a position away from the second shaft 21, and the second actuator 26 and crank disk 25C may be connected by a rod 125C. In the second joint 20C, the rotational motion of the second actuator 26 is transmitted to the second shaft 21 via the rod 125C and the crank disk 25C.

[0039] In each of the second joints 20A, 20B, and 20C, the second actuator 26 is provided at a position distant from the second shaft 21, but at least a portion of the structure of each of the second joints 20A, 20B, and 20C, including the second shaft 21, is disposed inside the recessed portion 8. With this configuration, the torque required to rotate the second shaft 21 can be reduced, similar to the second joint 20 (see FIG. 2(A)). Furthermore, the weight on the side of the simulated foot 5 relative to the second shaft 21 can be reduced, reducing the inertial force when moving the simulated foot 5 and allowing the simulated foot 5 to move quickly. Note that the configuration in which the second actuator 26 is provided at a position distant from the second shaft 21, as in each of the second joints 20A, 20B, and 20C, can also be similarly applied to the first joint 10 (see FIG. 2(A)). That is, the first actuator 16 can be provided at a position separate from the first shaft 11, and the first actuator 16 and the first shaft 11 can be connected via gears, belts and pulleys, or rods and crank discs.

[0040] 5, a second actuator 26E that moves in a linear direction using, for example, fluid pressure or electricity may be employed, and this second actuator 26E may be provided at a position away from the second shaft 21. In the example shown in FIG. 5, a pair of rods 125E are provided on the side surfaces of the second shaft 21 with the second shaft 21 sandwiched therebetween, and a second actuator 26E is provided at the end of each rod 125E. In this configuration, when each of the second actuators 26E is appropriately operated, the connected rods 125E move linearly back and forth in their longitudinal directions, causing the second shaft 21 to rotate back and forth about the second axis 22.

[0041] The gears, pulleys and belts, crank discs and rods, and linearly moving actuators and rods described above with reference to FIGS. 4(A) to 5 can be collectively referred to as power transmission members. Considering that an actuator is provided with an output shaft, it can also be referred to as a power transmission member. Furthermore, the first shaft 11 and second shaft 21 and their associated bearings, support members, and case in the embodiment shown in FIGS. 2(A) and 2(B) and the modified example shown in FIG. 3 can also be referred to as power transmission members. The power transmission member can be considered a member that transmits power for moving the simulated foot relative to the simulated lower leg. In the present disclosure, one embodiment in which at least a portion of the simulated joint is disposed within a recessed portion may be one in which at least a portion of the power transmission member is disposed within a recessed portion.

[0042] <Additional Notes> The following are additional notes regarding this disclosure.

[0043] (Appendix 1) A joint structure of a humanoid robot, A simulated lower leg, A simulated foot having a sole that faces the ground or floor in a standing position; a simulated joint that movably connects the simulated foot to the simulated lower leg; The simulated foot has a recess formed therein that is recessed from the opposite side of the sole toward the sole, At least a portion of the simulated joint is disposed inside the recess. Articulated structure.

[0044] (Appendix 2) The simulated joint is a first simulated joint that connects the simulated foot to the simulated lower leg so that the simulated foot can move around a first rotation axis; a second simulated joint that connects the simulated foot to the simulated lower leg so that the simulated foot can move around a second rotation axis that extends in a direction different from the first rotation axis; Including, At least a portion of at least one of the first simulated joint and the second simulated joint is disposed inside the recessed portion. 10. The articulated structure of claim 1.

[0045] (Appendix 3) a first actuator that rotates the imitation foot back and forth relative to the imitation lower leg around the first rotation axis; a second actuator that rotates the imitation foot back and forth around the second rotation axis relative to the imitation lower leg; 1. The articulated structure described in Appendix 2.

[0046] (Appendix 4) The recessed portion of the simulated foot is formed in a size and position such that the simulated lower leg does not interfere with the simulated foot during the reciprocating rotational movement by the first actuator and the reciprocating rotational movement by the second actuator. 10. The articulated structure of claim 3.

[0047] (Appendix 5) At least one of the first actuator and the second actuator has a motor and a reducer combined on the same axis as the first rotation axis or the second rotation axis. 5. The articulated structure of claim 3 or 4.

[0048] (Appendix 6) At least a part of the recessed portion of the simulated foot penetrates the sole of the foot. 6. The joint structure according to any one of claims 1 to 5.

[0049] (Appendix 7) a force sensor attached to the sole of at least one of the toe and heel of the simulated foot; 7. The joint structure according to any one of claims 1 to 6.

[0050] (Appendix 8) The simulated foot has a sole surface where the force sensor is attached receding to the opposite side of the sole surface. 10. The articulated structure of claim 7.

[0051] (Appendix 9) The joint structure according to any one of claims 1 to 8 is provided with two. Humanoid robot. [Explanation of symbols]

[0052] 1. Joint structure 3 Simulated lower leg 5 Simulated foot 6 Sole of the foot 8 Recessed part 8A penetration part 9. Imitation joints 10 First joint (first simulated joint) 12 First axis (first rotation axis) 16 First Actuator 17, 27 Motor 18, 28 reducer 20 Second joint (second simulated joint) 22 Second axis (second rotation axis) 26 Second Actuator 51 Force sensor 100 Humanoid Robots

Claims

1. A joint structure of a humanoid robot, A simulated lower leg, A simulated foot having a sole that faces the ground or floor in a standing position; a simulated joint that movably connects the simulated foot to the simulated lower leg; The simulated foot has a recess formed therein that is recessed from the opposite side of the sole toward the sole, At least a portion of the simulated joint is disposed inside the recess. Articulated structure.

2. The simulated joint is a first simulated joint that connects the simulated foot to the simulated lower leg so that the simulated foot can move around a first rotation axis; a second simulated joint that connects the simulated foot to the simulated lower leg so that the simulated foot can move around a second rotation axis that extends in a direction different from the first rotation axis; Including, At least a portion of at least one of the first simulated joint and the second simulated joint is disposed inside the recessed portion. The articulated structure according to claim 1 .

3. a first actuator that rotates the simulated foot back and forth relative to the simulated lower leg around the first rotation axis; a second actuator that causes the simulated foot to rotate back and forth around the second rotation axis relative to the simulated lower leg, The joint structure according to claim 2 .

4. The recessed portion of the simulated foot is formed to have a size and a position such that the simulated lower leg does not interfere with the simulated foot during the reciprocating rotational movement by the first actuator and the reciprocating rotational movement by the second actuator. The joint structure according to claim 3 .

5. At least one of the first actuator and the second actuator has a motor and a reducer combined on the same axis as the first rotation axis or the second rotation axis. The joint structure according to claim 3 .

6. At least a part of the recessed portion of the simulated foot penetrates the sole of the foot. The articulated structure according to claim 1 .

7. a force sensor attached to the sole of at least one of the toe and heel of the simulated foot; The articulated structure according to claim 1 .

8. The simulated foot has a sole surface where the force sensor is attached receding to the opposite side of the sole surface. The articulated structure according to claim 7.

9. A robot comprising two joint structures according to any one of claims 1 to 8. Humanoid robot.

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