Joint structure, robot and robot joint structure

Abstract

Provided is a joint structure comprising: a first link; a second link that is supported by the first link in a manner allowing rotation around a first axis, and bends relative to the first link; a third link that is supported by the second link in a manner allowing rotation around a second axis substantially perpendicular to or parallel to the first axis, and pivots relative to the second link; a first motor that is provided to the first link, and causes the rotation of the second link around the first axis; and a second motor that is provided to the second link, and causes the rotation of the third link around the second axis, wherein the drive axis of the second motor substantially matches the first axis.

Description

Technical Field

[0001] This invention relates to a joint structure or a robot having a joint structure.

Background Art

[0002] A robot arm or the like having a joint structure that rotates about an axis orthogonal or substantially orthogonal to the longitudinal axis of the link or the axis extending from the base to the tip of the link (hereinafter, this rotation may be simply referred to as bending), and rotates about the longitudinal axis of the link or the axis extending from the base to the tip of the link or an axis parallel thereto (hereinafter, this rotation may be simply referred to as turning) is known. According to this type of robot, various operations can be performed by taking advantage of its degrees of freedom.

[0003] For example, Patent Document 1 discloses a wrist drive structure of an industrial robot capable of performing bending (pivoting about the second axis b) and turning (pivoting about the third axis c).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional joint structure exemplified in Patent Document 1, the motor that causes bending and the motor that causes turning are arranged within a single link on the arm base side. As a result, it has been difficult to reduce the diameter and length of the link. That is, considering the arrangement of actuators such as motors, it is still hard to say that the miniaturization of the joint structure has been sufficiently achieved.

[0006] This invention has been made in view of the above technical background, and its object is to miniaturize a joint structure capable of bending and turning. [Means for solving the problem]

[0007] The technical problems described above can be solved by a joint structure having the following configuration.

[0008] In other words, the joint structure according to the present invention comprises a first link, a second link supported by the first link so as to be rotatable around a first axis and bending relative to the first link, a third link supported by the second link so as to be rotatable around a second axis which is substantially perpendicular to or parallel to the first axis and pivoting relative to the second link, a first motor provided on the first link that causes the second link to rotate around the first axis, and a second motor provided on the second link that causes the third link to rotate around the second axis, wherein the drive shaft of the second motor substantially coincides with the first axis.

[0009] With this configuration, the second motor, which is part of the mechanism that brings about pivoting motion between the second and third links, is positioned approximately on the axis that brings about bending motion between the first and second links. This optimizes the arrangement, including the motor. In other words, the joint structure capable of bending and pivoting can be miniaturized.

[0010] The system further includes a second reduction gear provided on the power transmission path between the second motor and the third link, which reduces the output of the second motor, and the second reduction gear may include a three-stage orthogonal reduction gear.

[0011] With this configuration, the second reduction gear can convert the output of the second motor into rotation around the second axis that causes turning in the shortest possible time, and the structure can be made smaller by reducing the number of protrusions.

[0012] The orthogonal reduction gear may include at least a second hypoid mechanism comprising a second pinion gear and a second ring gear.

[0013] This configuration provides a joint structure that ensures backdrivability, high torsional rigidity, and stable operation over a wide temperature range.

[0014] The shortest distance between the extension of the first axis and the extension of the second axis may coincide with the offset amount of the second pinion gear from the center of the second ring gear.

[0015] With this configuration, the range of motion of the joint structure can be ensured by the offset.

[0016] The orthogonal reducer may include, in order, a first bevel gear mechanism including a pair of bevel gears, a second hypoid gear mechanism consisting of a second pinion gear and a second ring gear, and a second bevel gear mechanism including a pair of bevel gears, in the power transmission path from the second motor to the third link.

[0017] With this configuration, the second reduction gear can convert the output of the second motor into rotation around the second axis in the shortest possible time, and a structure with fewer protrusions can be achieved, thus enabling miniaturization of the joint structure. Furthermore, it is possible to provide a joint structure that ensures backdrivability, high torsional rigidity, and stable operation over a wide temperature range.

[0018] The system further includes a first reduction gear provided on the power transmission path between the first motor and the second link, which reduces the output of the first motor, and the first reduction gear may include a first hypoid mechanism comprising a first pinion gear and a first ring gear.

[0019] This configuration provides a joint structure that ensures backdrivability, high torsional rigidity, and stable operation over a wide temperature range.

[0020] The first speed reducer may include, in the power transmission path from the first motor to the second link, in order, a first transmission mechanism that transmits the output of the first speed reducer, and the first hypoid mechanism, and the drive shaft of the first motor may be parallel to the rotation center axis of the first pinion gear.

[0021] According to such a configuration, since the drive shaft of the first motor, which is a part of the mechanism that causes a bending operation between the first link and the second link, is parallel to the rotation center axis of the first pinion gear, the cross-section orthogonal to the first drive shaft or the rotation center axis can be reduced, and the joint can be miniaturized.

[0022] The first transmission mechanism may be a pulley mechanism composed of a pair of pulleys and a belt.

[0023] According to such a configuration, the drive shaft of the first motor can be converted to be parallel to the rotation center axis of the first pinion gear, and power can be transmitted smoothly.

[0024] The first transmission mechanism may be a spur gear mechanism composed of a plurality of spur gears.

[0025] According to such a configuration, the drive shaft of the first motor can be converted to be parallel to the rotation center axis of the first pinion gear, and power can be transmitted without concerns such as slipping.

[0026] The encoder may further include an encoder disk and a reading board that reads the encoder disk, and one of the encoder disk and the reading board may be provided on the second motor, and the other may be provided on the first link.

[0027] According to such a configuration, by utilizing the fact that the drive shaft of the second motor substantially coincides with the first axis, the encoder can be arranged compactly with a simple configuration.

[0028] The second link may be supported to the first link via two pivot support members, the first pivot support member and the second pivot support member, which are arranged parallel to each other so as to share a common central axis.

[0029] This configuration allows for increased rigidity of the joint structure.

[0030] The second motor may be positioned between the first and second rotational support members, with a first space provided on the drive shaft of the second motor on the output shaft side of the second motor and on the rear side of the first rotational support member as viewed from the second motor, while a second space provided on the drive shaft of the second motor on the opposite side of the output shaft of the second motor and on the rear side of the second rotational support member as viewed from the second motor, with a part of the mechanism for transmitting driving force from the second motor to the third link provided in the first space, and a drive board for driving the first motor and / or the second motor provided in the second space.

[0031] With this configuration, the necessary components can be compactly arranged in the front-to-rear space above the drive shaft of the second motor. This makes it possible to miniaturize the joint structure.

[0032] The appearance of the first link, the second link, and the third link may be configured to be symmetrical.

[0033] With this configuration, the joint structure can be applied to either of the left and right pair of joint structures.

[0034] Viewed from a different angle, the present invention is an articulated structure comprising: a first link; a second link supported by the first link so as to be rotatable around a first axis and bending relative to the first link; a third link supported by the second link so as to be rotatable around a second axis which is substantially perpendicular to or parallel to the first axis and pivoting relative to the second link; a first motor provided on the first link to cause the second link to rotate around the first axis; a second motor provided on the second link to cause the third link to rotate around the second axis; and the first motor and the The system includes a first reduction gear provided on the power transmission path between the second link and the third link, which reduces the output of the first motor, and a second reduction gear provided on the power transmission path between the second motor and the third link, which reduces the output of the second motor, wherein the drive shaft of the second motor substantially coincides with the first shaft, the first reduction gear includes a first hypoid mechanism consisting of a first pinion gear and a first ring gear, and the second reduction gear includes a three-stage orthogonal reduction gear, which includes a second hypoid mechanism consisting of at least a second pinion gear and a second ring gear.

[0035] This configuration provides a compact joint structure that ensures backdrivability, high torsional rigidity, and stable operation over a wide temperature range.

[0036] Viewed from a different angle, the present invention is a robot comprising a joint structure including a first link, a second link supported by the first link so as to be rotatable around a first axis and bending relative to the first link, a third link supported by the second link so as to be rotatable around a second axis which is substantially perpendicular to or parallel to the first axis and pivoting relative to the second link, a first motor provided on the first link that causes the second link to rotate around the first axis, and a second motor provided on the second link that causes the third link to rotate around the second axis, wherein the drive axis of the second motor substantially coincides with the first axis.

[0037] Viewed from a different perspective, the present invention is a robot joint structure comprising: a first link; a second link supported by the first link so as to be rotatable around a first axis and bending relative to the first link; a third link supported by the second link so as to be rotatable around a second axis which is substantially perpendicular to or parallel to the first axis and pivoting relative to the second link; a first motor provided on the first link that causes the second link to rotate around the first axis; and a second motor provided on the second link that causes the third link to rotate around the second axis, wherein the drive axis of the second motor substantially coincides with the first axis. [Effects of the Invention]

[0038] According to the present invention, a joint structure capable of bending and rotating can be miniaturized. [Brief explanation of the drawing]

[0039] [Figure 1] Figure 1 is a perspective view of the elbow joint of a robotic arm. [Figure 2] Figure 2 is a transparent perspective view showing the internal structure of the upper arm linkage. [Figure 3] Figure 3 is a perspective view showing the internal structure of the upper arm linkage. [Figure 4] Figure 4 is a schematic diagram illustrating the principle of transmission of rotational driving force from the first motor. [Figure 5] Figure 5 is a transparent perspective view showing the internal structure of the first forearm linkage. [Figure 6] Figure 6 is a perspective view showing the internal structure of the first forearm linkage. [Figure 7] Figure 7 is a schematic diagram illustrating the principle of transmission of rotational driving force from the second motor. [Figure 8] Figure 8 is a schematic diagram illustrating the principle of the joint structure that provides flexion and rotation. [Figure 9] Figure 9 is a front view of the robot arm. [Figure 10] Figure 10 is a perspective view of the robot arm as seen from the front. [Figure 11]Figure 11 is a conceptual diagram showing a side view of a portion of the internal structure related to the elbow of a robot arm. [Figure 12] Figure 12 shows a modified example of the configuration for transmitting the rotational driving force of the second motor. [Modes for carrying out the invention]

[0040] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0041] (1. First Embodiment) As a first embodiment, an example in which the joint structure according to the present invention is applied to the elbow joints of a pair of left and right arms of a humanoid robot will be described. Note that the joint structure according to the present invention can be applied to any joint that requires flexion and rotation. Therefore, it can also be applied to joints other than the elbow joint, such as the shoulders and waist of a robot.

[0042] In this embodiment, bending refers to rotation around an axis (bending axis) that is perpendicular or nearly perpendicular to the longitudinal axis of the link or the axis extending from the base to the tip of the link. Swivel refers to rotation around the longitudinal axis of the link or the axis extending from the base to the tip of the link, or an axis parallel thereto.

[0043] Figure 1 is an external perspective view of the elbow joint of a robot arm. As is clear from the figure, in this embodiment, the elbow joint of the robot arm comprises an upper arm link 1 (or first link) that constitutes the portion from the upper arm to the center of the elbow, a first forearm link 3 (or second link) that constitutes the portion from the sides of the elbow to the forearm, and a second forearm link 5 (or third link) that is positioned near the tip of the first forearm link 3 and provides a connection to other members at its tip. By the relative rotation of these links, bending or swiveling motions are achieved.

[0044] More specifically, the lower end of the upper arm link 1 is provided with a first forearm link 3 connected to both sides of it in a double-support manner. The bending motion of the robot arm is achieved by the rotation of these upper arm link 1 and first forearm link 3 around the A1 axis, which is depicted horizontally in the figure.

[0045] A second forearm link 5 is provided at the lower end of the first forearm link 3, which rotates around an axis parallel to the longitudinal axis of the robot arm. By rotating these first forearm link 3 and second forearm link 5 around the A2 axis, which is drawn vertically in the figure, the robot arm can perform a rotational motion.

[0046] Figures 2 and 3 illustrate the configuration related to rotation around the A1 axis, i.e., flexion. Figure 2 is a transmissive perspective view showing the internal configuration of the upper arm link 1, and Figure 3 is a perspective view of the internal configuration of the upper arm link 1.

[0047] As is clear from these figures, a cylindrical motor cover 11 is positioned at the upper center of the upper arm link 1, its position fixed by a motor support member 12. Inside the motor cover 11 are a first motor 111 (not shown) and an encoder 112 (not shown) for detecting the rotation angle of the first motor 111. The output shaft of the first motor 111 protrudes from the lower end of the motor cover 11.

[0048] On the side of the motor cover 11 opposite to the side from which the output shaft of the first motor 111 protrudes, a first brake mechanism 14 is positioned to brake the rotation of the first motor 111.

[0049] The output shaft of the first motor 111 is coupled to the center of the first pulley 131. The first pulley 131 is coupled to the second pulley 133 via a belt 132, and the rotation of the first pulley 131 is transmitted to the second pulley.

[0050] The first pinion gear 15 is coupled to the center of the second pulley 133, parallel to the output shaft of the first motor 111 and perpendicular to the second pulley 133.

[0051] With this configuration, the drive shaft of the first motor is parallel to the pivot axis of the first pinion gear, so the cross-section perpendicular to the first drive shaft or pivot axis can be reduced, and the joint can be miniaturized.

[0052] In this embodiment, the output of the first motor 111 is transmitted by a pulley mechanism, but the present invention is not limited to this configuration. Therefore, other configurations can be adopted, such as a spur gear mechanism consisting of multiple spur gears. With spur gears, power can be transmitted without concerns about slippage.

[0053] The first pinion gear 15 is covered by a first pinion gear cover 161 and a second pinion gear cover 163, starting from the side closest to the second pulley 133. These cover members are fixed to the retaining member 162.

[0054] Bearings 1611 and 1631 are located inside the first pinion gear cover and the second pinion gear cover 163, respectively, supporting the rotation of the first pinion gear at two points.

[0055] The tip of the first pinion gear meshes with the first ring gear 17, which constitutes the first hypoid gear, such that their respective pivot axes are in a twisted position. The ring gear can also be called, for example, a bevel gear. The rotation of this first ring gear 17 causes the first forearm link 3 to rotate relative to the upper arm link 1, that is, the robot arm to bend.

[0056] With this configuration, since hypoid gears are used, it is possible to provide a joint structure that ensures backdrivability, high torsional rigidity, and stable operation over a wide temperature range.

[0057] The first ring gear 17 is rotatably held on the inner circumference side of a cross roller bearing 18, which is held by a ring-shaped bearing holding member 22 fixed to the upper arm link 1.

[0058] Furthermore, an annular bearing 19 is positioned on the opposite side of the cross roller bearing 18, across from the first pinion gear. These cross roller bearings 18 and 19 support the rotation of the first forearm link 3 relative to the upper arm link 1 by the hypoid gear, thereby enabling flexion.

[0059] Furthermore, the encoder reading board 20 is fixed to the upper arm link 1 via a columnar member 21. As will be described later, the bending angle is detected using this encoder reading board 20.

[0060] Figure 4 is a schematic diagram illustrating the principle of how the rotational driving force from the first motor 111 is transmitted to the first ring gear 17, which constitutes the first hypoid gear. As this is a schematic diagram, each component is shown in a simplified manner.

[0061] As is clear from the figure, the tip of the output shaft of the first motor 111 is perpendicularly connected to the center of the first pulley 131.

[0062] Next to the first pulley 131, a second pulley 133 is positioned parallel to the first pulley 131. The first pulley 131 and the second pulley 133 are connected via a belt 132, and rotational power is transmitted from the first pulley 131 to the second pulley 133.

[0063] A first pinion gear 15, which constitutes the first hypoid gear, is coupled to the center of the second pulley 133 perpendicular to the second pulley 133. The rotation of the first pinion gear 15 is supported by two bearings 1611 and 1631.

[0064] The tip of the first pinion gear 15 meshes with the first ring gear 17, which constitutes the first hypoid gear. The first ring gear 17 is supported by a cross roller bearing 18 so as to rotate around the A1 axis (bending axis). The first ring gear 17 is coupled to the first annular member 31, which will be described later.

[0065] In other words, with the above configuration, the first annular member 31 can be rotated around the A1 axis by driving the first motor 111 via the reduction mechanism, or in other words, via two orthogonal conversion mechanisms consisting of a pair of pulley mechanisms 131-133 and the first hypoid gear.

[0066] Figures 5 and 6 are explanatory diagrams illustrating the configuration related to the rotational movement caused by rotation around the A2 axis. Figure 5 is a transmission perspective view showing the internal configuration of the first forearm link 3, and Figure 6 is a perspective view showing the internal configuration of the first forearm link 3.

[0067] As is clear from these figures, the first annular member 31 and the second annular member 32 are arranged opposite each other with a common central axis, along the inner circumference of a pair of cylindrical portions provided on the upper side surface of the first forearm link 3. As mentioned above, the first annular member 31 is connected to the first ring gear 17.

[0068] A second motor cover 35 is positioned between the first annular member 31 and the second annular member 32 such that its output shaft coincides with the annular centers of the first annular member 31 and the second annular member 32. The second motor cover 35 is fixed to the first annular member 31 and rotates together with the first annular member about the A1 axis. The first annular member and the second annular member 32 are both fixed to the first forearm link 3 and rotate together about the A1 axis.

[0069] With this configuration, the first forearm link 3 is connected to the upper arm link 1 in a so-called double-supported manner, with the lower end of the upper arm link 1 supported from both sides by the first annular member 31 and the second annular member 2, thereby increasing the rigidity of the joint structure.

[0070] In this embodiment, a link refers to a member that connects joints. Therefore, the structural members including the first annular member 31 and the second annular member 32 may be collectively referred to as the first forearm link 3.

[0071] Inside the second motor cover 35, the second motor 351 is positioned. The output shaft of the second motor 351 protrudes from the side of the first annular member 31, and on the side opposite to the surface from which the output shaft protrudes, a second brake mechanism 36 is positioned to brake the rotation of the second motor 351.

[0072] A first bevel gear 39 is coupled to the tip of the output shaft of the second motor 351. The first bevel gear 39 meshes with a second bevel gear 40, whose rotational axis is perpendicular to that of the first bevel gear 39. The second bevel gear 40 is coupled concentrically with the second pinion gear 41, which constitutes the second hypoid gear.

[0073] The upper end of the second pinion gear 41 is rotatably supported by a bearing 381, which is fixed to the first annular member 31 using a fixing device 38.

[0074] Directly below the second bevel gear 40, a stepped portion 441 is provided as part of the shaft of the second pinion gear 41. The second pinion gear passes through the first annular member 31 from its inner circumference as an extension of the stepped portion 441. A bearing 382 (not shown) is positioned on the inner circumference of the through-hole in the first annular member 31, supporting the rotation of the second pinion gear 41. In other words, the second pinion gear 41 is rotatably supported at two points by the two bearings 381 and 382.

[0075] The tip of the second pinion gear 41, which protrudes from the outer circumference of the first annular member 31, meshes with the second ring gear 42, which constitutes the second hypoid gear, such that their respective pivot axes are in a twisted positional relationship. The ring gear can also be referred to as a bevel gear, for example.

[0076] With this configuration, since hypoid gears are used, it is possible to provide a joint structure that ensures backdrivability, high torsional rigidity, and stable operation over a wide temperature range.

[0077] A concentric cylindrical member 47 (not shown in the figure) is coupled to the side of the second ring gear 42 opposite to the side that engages with the second pinion gear 41. The rotation of the cylindrical member 47 is supported by two bearings 471 and 472. A third bevel gear 43 is coupled to the end of the cylindrical member 47 opposite to the end that engages with the second ring gear 42.

[0078] The third bevel gear 43 meshes with the fourth bevel gear 45, whose rotational axis is perpendicular to that of the fourth bevel gear 45 and whose meshing surface is oriented upward.

[0079] A cylindrical member 48 is concentrically coupled to the face of the fourth bevel gear 45 opposite to the meshing face. The cylindrical member 48 is rotatably supported by a cross roller bearing 46 fixed to the first forearm link 3.

[0080] The end of the cylindrical member opposite to the end connected to the fourth bevel gear 45 is connected to the second forearm link 5.

[0081] Although not shown in the figure, an encoder is positioned between the first forearm link 3 and the second forearm link 5 to detect the rotation angle around the A2 axis.

[0082] Figure 7 is a schematic diagram illustrating the principle of how the rotational driving force from the second motor 351 is transmitted to the second forearm link 5. As this is a schematic diagram, each component is shown in a simplified manner.

[0083] As is clear from the figure, the tip of the output shaft of the second motor 351 is coupled to the first bevel gear 39. The first bevel gear 39 meshes with the second bevel gear, which is positioned perpendicular to it in axis of rotation. The second bevel gear 40 is annular in shape and fixed at an appropriate position near the center of the rod-shaped second pinion gear 41. In other words, the rotation of the second bevel gear 40 causes the second pinion gear 41 to rotate as well.

[0084] The second pinion gear 41 is supported by two bearings 381 and 382 that sandwich the second bevel gear 40, allowing it to rotate at two points. The tip of the second pinion gear 41 meshes with the second ring gear 42, which constitutes the second hypoid gear, such that their respective rotational axes are in a twisted positional relationship.

[0085] A cylindrical member 47 is concentrically coupled to the side of the second ring gear 42 opposite to the side that engages with the second pinion gear 41. The rotation of the cylindrical member 47 is supported by two bearings. A third bevel gear 43 is coupled to the end of the cylindrical member 47 opposite to the end that is coupled to the second ring gear 42.

[0086] The third bevel gear 43 meshes with the fourth bevel gear 45, whose rotational axis is perpendicular to that of the fourth bevel gear 45 and whose meshing surface is oriented upward in the figure.

[0087] A cylindrical member 48 is concentrically coupled to the face of the fourth bevel gear 45 opposite to the meshing face. The cylindrical member 48 is rotatably supported by a cross roller bearing 46 fixed to the first forearm link 3.

[0088] The end of the cylindrical member opposite to the end connected to the fourth bevel gear 45 is connected to the second forearm link 5.

[0089] In other words, with the above configuration, the second forearm link 5 can be rotated around the A2 axis, which is perpendicular to the output shaft of the second motor 351, via a three-stage orthogonal reduction mechanism consisting of the meshing of the first bevel gear 39 and the second bevel gear 40, the meshing of the second pinion gear 41 and the second ring gear 42, and the meshing of the third bevel gear 43 and the fourth bevel gear 45, by the drive of the second motor 351.

[0090] Furthermore, this reduction mechanism allows the output of the second motor to be converted into rotation around the second axis in the shortest possible time, and also enables a structure with fewer protrusions, thus allowing for miniaturization of the joint structure.

[0091] Figure 8 is a schematic diagram illustrating the configuration that provides bending and rotation to a robot arm. As this is a schematic diagram, each component is shown in a simplified manner.

[0092] The power transmission paths from each motor 111 and 351 to each component have already been explained in Figures 1 to 7, so a detailed explanation will be omitted here.

[0093] As is clear from the figure, the drive axis of the second motor 351 coincides with the rotation axis of the first forearm link 3 relative to the upper arm link 1, i.e., the A1 axis.

[0094] With this configuration, the second motor 351, which is part of the mechanism that brings about rotational movement between the first forearm link 3 and the second forearm link 5, is positioned approximately on the axis that brings about flexion movement between the upper arm link 1 and the first forearm link 3. As a result, the arrangement, including the motor, is optimized. This makes it possible to miniaturize the joint structure that is capable of both flexion and rotation.

[0095] An annular disk 202, which constitutes an encoder, is attached to the side of the output shaft of the second motor 351 opposite to the protruding side. Meanwhile, an encoder reading board 20 is attached near the tip of the upper arm link 1. A reading element 201 is positioned on the encoder reading board 20 so as to face the disk 202. By reading the pattern on the disk 202, i.e., the encoded information, the rotation angle of the second motor 351, i.e., the bending angle, is detected.

[0096] With this configuration, the fact that the drive shaft of the second motor substantially coincides with the first shaft allows for a compact arrangement of the encoder in a simple configuration.

[0097] An annular disk 302, which constitutes an encoder, is fixed to the lower end of the first forearm link 3. An encoder reading board 501, which also constitutes an encoder, is attached to the lower end of the second forearm link 5. A reading element 502 is positioned on the encoder reading board 20 so as to face the disk 302. By reading the pattern, i.e., the encoded information, on the disk 302, the reading element 502 detects the rotation angle, i.e., the swivel angle, relative to the second forearm link 5 relative to the first forearm link 3.

[0098] Furthermore, a drive board 37 for driving the second motor 351 is positioned on the back side of the second annular member 32, on the extension of the center line (A1 axis) on the side opposite to the side from which the output shaft of the second motor 351 protrudes.

[0099] Figures 9 and 10 show the robot arm as viewed from the front. Figure 9 is a front view of the robot arm, and Figure 10 is a perspective view of the robot arm as viewed from the front.

[0100] As is clear from these diagrams, the robot arm housing is constructed symmetrically.

[0101] With this configuration, the joint structure can be applied to either of the left and right pair of joint structures.

[0102] Furthermore, as is clear from the figure, a first space 481, surrounded by the first annular member 31 and the inner circumferential surface of the first forearm link 3, and a second space 482, surrounded by the second annular member 32 and the inner circumferential surface of the first forearm link 3, are provided symmetrically on the front and rear sides of the drive axis of the second motor 351 of the robot arm.

[0103] The first space 481 contains the components extending from the output shaft of the second motor 351 to the second pinion gear 41. The second space 482 contains the drive board 37 for driving the second motor.

[0104] This configuration allows for the provision of a symmetrical joint structure while accommodating the necessary mechanisms.

[0105] Figure 11 is a conceptual diagram showing a side view of part of the internal structure of the elbow portion of the robot arm. The upper half of the figure shows the second pinion gear 41 connected to the output shaft of the second motor 351 via the first bevel gear 39 and the second bevel gear 40. The lower half shows part of the structure from the second ring gear 42 to the second forearm link 5.

[0106] As is clear from the figure, the second pinion gear 41, which constitutes the second hypoid gear, meshes with the second ring gear 42, which also constitutes the second hypoid gear, at an offset of distance d from the center of the second ring gear, when the robot arm is observed from the side. This distance d is the same as the offset of the pinion gear axis relative to the ring gear center in the hypoid gear. As a result, when the robot arm is observed from the side, the A1 axis, which is the bending axis, and the A2 axis, which is the pivot axis, are also positioned at an offset of distance d.

[0107] With this configuration, a greater range of motion can be secured compared to a configuration in which there is no offset between the bending axis and the pivot axis.

[0108] (2. Variant) The present invention is not limited to the embodiments described above and can be implemented in various modified forms.

[0109] In the embodiments described above, a mechanism for transmitting the output of the second motor 351 on the bending axis to a pivot axis perpendicular to the bending axis was described using three orthogonal conversion mechanisms: an orthogonal conversion using the first bevel gear 39 and the second bevel gear 40, an orthogonal conversion using the second pinion gear 41 and the second ring gear 42, and an orthogonal conversion using the third bevel gear 43 and the fourth bevel gear 45. However, the present invention is not limited to such a configuration, and other configurations can be adopted.

[0110] Figure 12 shows a modified example of a mechanism for transmitting the output of the second motor 351 to the second forearm link 5. As is clear from the figure, a third pulley 61 is provided at the tip of the output shaft of the second motor 351. The third pulley is coupled to a fourth pulley 62, whose rotation axis is orthogonal to it, via a belt 63, and the fourth pulley is coupled to a fifth pulley 64, whose rotation axis is orthogonal to it, via a belt 65. In other words, rotation around the A1 axis is converted to rotation around the A2 axis via the three pulleys from the third pulley 61 to the fifth pulley 64.

[0111] After this conversion, a reduction gear 66 is positioned between the fifth pulley 64 and the second forearm link 5. The reduction gear 66 can be, for example, a harmonic drive gear, a planetary gear, or a combination thereof. This reduction gear 66 performs the necessary reduction.

[0112] With this configuration, the direction of the pivot axis can be changed in advance, and then deceleration can be performed all at once.

[0113] Although embodiments of the present invention have been described above, these embodiments represent only a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. Furthermore, the above embodiments can be combined as appropriate, as long as no contradictions arise. [Industrial applicability]

[0114] This invention can be used in industries that manufacture robots and the like. [Explanation of symbols]

[0115] 1. Upper arm link 11. First motor cover 131 First Pulley 132 belts 133 Second Pulley 15. First pinion gear 17. First Ring Gear 3. First forearm link 31 First annular member 32 Second annular member 35. Second motor cover 39. First bevel gear 40 Second Umbrella Gear 41. Second pinion gear 42. Second Ring Gear 43 Third bevel gear 45 Fourth bevel gear 5. Second forearm link

Claims

1. The first link, A second link is supported by the first link so as to be rotatable around a first axis and bends relative to the first link, A third link is supported by the second link so as to be rotatable around a second axis which is substantially perpendicular to or parallel to the first axis, and pivots relative to the second link, A first motor is provided on the first link and causes the second link to rotate around the first axis, The system includes a second motor provided on the second link, which causes the third link to rotate around the second axis, The drive shaft of the second motor is substantially aligned with the first shaft. The second link is supported to the first link via two pivot support members, the first and second pivot support members being arranged parallel to each other so as to share a common central axis, forming an articulated structure.

2. The system further includes a second reduction gear provided on the power transmission path between the second motor and the third link, which reduces the output of the second motor. The articulated structure according to claim 1, wherein the second reduction gear includes a three-stage orthogonal reduction gear.

3. The articulated structure according to claim 2, wherein the orthogonal reducer includes at least a second hypoid mechanism comprising a second pinion gear and a second ring gear.

4. The joint structure according to claim 3, wherein the shortest distance between the extension line of the first axis and the extension line of the second axis coincides with the amount of offset of the second pinion gear from the center of the second ring gear.

5. The articulated structure according to claim 2, wherein the orthogonal reducer includes, in order, a first bevel gear mechanism including a pair of bevel gears, a second hypoid gear mechanism consisting of a second pinion gear and a second ring gear, and a second bevel gear mechanism including a pair of bevel gears, in the power transmission path from the second motor to the third link.

6. The system further includes a first reduction gear provided on the power transmission path between the first motor and the second link, which reduces the output of the first motor. The articulated structure according to any one of claims 1 to 5, wherein the first reduction gear includes a first hypoid mechanism comprising a first pinion gear and a first ring gear.

7. The first reduction gear includes, in order, a first transmission mechanism that transmits the output of the first reduction gear and a first hypoid mechanism along a power transmission path from the first motor to the second link. The joint structure according to claim 6, wherein the drive shaft of the first motor is parallel to the rotational center axis of the first pinion gear.

8. The joint structure according to claim 7, wherein the first transmission mechanism is a pulley mechanism consisting of a pair of pulleys and a belt.

9. The joint structure according to claim 7, wherein the first transmission mechanism is a spur gear mechanism consisting of a plurality of spur gears.

10. The encoder further comprises an encoder disk and a reading board for reading the encoder disk, The joint structure according to any one of claims 1 to 9, wherein one of the encoder disk and the reading board is provided on the second motor, and the other is provided on the first link.

11. The second motor is positioned between the first rotation support member and the second rotation support member. A first space is located on the drive shaft of the second motor, on the output shaft side of the second motor and on the rear side of the first pivot support member as viewed from the second motor; on the other hand, a second space is located on the drive shaft of the second motor, on the opposite side of the output shaft of the second motor and on the rear side of the second pivot support member as viewed from the second motor. The joint structure according to claim 1, wherein a part of a mechanism for transmitting driving force from the second motor to the third link is arranged in the first space, and a drive board for driving the first motor and / or the second motor is arranged in the second space.

12. The joint structure according to claim 11, wherein the appearance of the first link, the second link, and the third link is configured to be symmetrical.

13. The first link, A second link is supported by the first link so as to be rotatable around a first axis and bends relative to the first link, A third link is supported by the second link so as to be rotatable around a second axis which is substantially perpendicular to or parallel to the first axis, and pivots relative to the second link, A first motor is provided on the first link and causes the second link to rotate around the first axis, A second motor is provided on the second link, which causes the third link to rotate around the second axis, A first reduction gear is provided on the power transmission path between the first motor and the second link, and reduces the output of the first motor. The system includes a second reduction gear, which is provided on the power transmission path between the second motor and the third link and reduces the output of the second motor, The drive shaft of the second motor is substantially aligned with the first shaft. The first reduction gear includes a first hypoid mechanism consisting of a first pinion gear and a first ring gear. The second reduction gear includes a three-stage orthogonal reduction gear, The orthogonal reduction gear includes at least a second hypoid mechanism consisting of a second pinion gear and a second ring gear. The second link is supported to the first link via two pivot support members, the first and second pivot support members being arranged parallel to each other so as to share a common central axis, forming an articulated structure.

14. The first link, A second link is supported by the first link so as to be rotatable around a first axis and bends relative to the first link, A third link is supported by the second link so as to be rotatable around a second axis which is substantially perpendicular to or parallel to the first axis, and pivots relative to the second link, A first motor is provided on the first link and causes the second link to rotate around the first axis, The system includes a second motor provided on the second link, which causes the third link to rotate around the second axis, The drive shaft of the second motor is substantially aligned with the first shaft. A robot with an articulated structure, wherein the second link is supported to the first link via two rotational support members, the first rotational support member and the second rotational support member being arranged parallel to each other so as to share a common central axis.

15. The first link, A second link is supported by the first link so as to be rotatable around a first axis and bends relative to the first link, A third link is supported by the second link so as to be rotatable around a second axis which is substantially perpendicular to or parallel to the first axis, and pivots relative to the second link, A first motor is provided on the first link and causes the second link to rotate around the first axis, The system includes a second motor provided on the second link, which causes the third link to rotate around the second axis, The drive shaft of the second motor is substantially aligned with the first shaft. A robot joint structure in which the second link is supported to the first link via two rotational support members, the first rotational support member and the second rotational support member being arranged parallel to each other so as to share a common central axis.

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