JP2020124776A - Joint mechanism - Google Patents

Abstract

To provide a joint mechanism which has a plurality of degrees of freedom, a small size and a light weight, and can be easily installed on an arm.SOLUTION: A joint mechanism 10A comprises: a base end bevel gear 50 which is provided between an arm 14a and an arm 14b, and is rotatable around a shaft J1; an intermediate bevel gear 58 which is rotatable around a shaft J2; and a tip bevel gear 76 which is rotatable around a shaft J3, and further comprises at least two of: a base end motor 38 which rotates the base end bevel gear 50 around the shaft J1; an intermediate motor 54 which rotates the intermediate bevel gear 58 around the shaft J2; and a tip motor 68 which rotates the tip bevel gear 76 around the shaft J3. The arm 14a and the arm 14b are relatively rotatable around a reference axis 60. Power transmission is performed by engagement of the base end bevel gear 50 and the intermediate bevel gear 58. Power transmission is performed by engagement of the intermediate bevel gear 58 and the tip bevel gear 76. The arm 14b can perform a turning operation and an elevating operation.SELECTED DRAWING: Figure 10

Description

The present invention relates to a joint mechanism provided between two arms.

A multi-joint type arm that is often used in industrial robots is generally provided with a rotary joint having one degree of freedom between the arms. Therefore, the multi-joint arm has joints and arms as many as the number of degrees of freedom, and thus is lengthened. In addition, the industrial robot is stationary and heavy.

For example, when shooting a camera with a small flying object such as a drone, it is preferable to be able to adjust the direction of the camera with a multi-joint arm, but a small and lightweight multi-joint arm that can be mounted on a small flying object has been developed. Not not. In order to realize such a compact and lightweight multi-joint arm, it is desirable that one joint can realize a plurality of degrees of freedom. This is because the number of arms can be reduced accordingly.

Patent Document 1 discloses a joint mechanism having two degrees of freedom. In this joint mechanism, a rotary pivot joint and a rotary swivel joint are combined, and each is driven by a wire cable.

JP, 2010-255852, A

The joint mechanism described in Patent Document 1 is considered to be small and lightweight to some extent, but since it is driven by a wire cable, it has poor control accuracy and it is difficult to install the wire cable. In particular, when a joint mechanism is provided between the three or more arms, it is considered that the wire cable is extremely difficult to arrange, and the accuracy of the tip arm is considerably deteriorated due to the influence of elongation and the like.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a joint mechanism that is small and lightweight, easy to install on an arm, and capable of highly accurate operation.

In order to solve the above-mentioned problems and to achieve the object, a joint mechanism according to the present invention is a joint mechanism provided between two arms, and is a first mechanism that extends along one arm with an axis of the first conical surface. A base cone that is rotatable about one axis, an intermediate cone that is rotatable about a second axis on the second cone surface, and a third cone along the other arm on the axis on the third cone surface. A tip cone that is rotatable about an axis, and further rotates the base cone about the first axis to provide a first motor provided on the one arm, and the intermediate cone. A second motor that rotates about the second shaft as a center, and a third motor that rotates the tip cone about the third shaft and that is provided on the other arm. The one arm and the other arm are configured to be relatively rotatable about a reference axis, and the first conical surface and the second conical surface are in contact with each other, whereby the proximal cone and the conical body are connected. Power transmission is performed between the intermediate cone and the second conical surface and the third conical surface are in contact with each other, so that power is transmitted between the intermediate cone and the proximal cone. Is characterized by.

Three of the first motor, the second motor, and the third motor may be provided.

Further, the joint mechanism according to the present invention is a joint mechanism provided between two arms, and is a proximal cone body that is rotatable about a first axis along one arm by an axis of the first conical surface. An intermediate cone that is rotatable about the second axis of the second conical surface, and a tip cone that is rotatable about the third axis along the other arm of the axis of the third conical surface, A first motor that rotates the proximal cone about the first axis and that is provided on the one arm; a second motor that rotates the intermediate cone about the second axis; and the tip. A linear motion mechanism that expands and contracts based on a cone rotating around the third axis, and the one arm and the other arm are configured to be relatively rotatable about a reference axis. When the first conical surface and the second conical surface are in contact with each other, power is transmitted between the proximal conical body and the intermediate conical body, and the second conical surface and the third conical surface are connected. Is abutted against each other to transmit power between the intermediate cone and the base cone.

The linear motion mechanism may include a male screw portion and a female screw portion that are screwed together, and one of the male screw portion and the female screw portion may rotate to move the other forward or backward.

The base cone, the intermediate cone and the tip cone may have the same diameter.

The base cone and the tip cone may have the same diameter, and the intermediate cone may have a larger diameter than the base cone and the tip cone.

At a predetermined timing, the contact position between the base cone and the intermediate cone in the reference posture is shifted, and the contact position between the intermediate cone and the tip cone in the reference posture is shifted. You may have the control part to operate.

Further, the joint mechanism according to the present invention is a joint mechanism provided between two arms, and is a first cone body that is rotatable about a first axis along one arm with an axis of the first cone surface. And a second conical body rotatable about a second axis on the second conical surface, and a first motor provided on the one arm for rotating the first conical body about the first axis. And a second motor for rotating the second cone about the second axis, and the other arm is provided rotatably about the second axis together with the second cone. Power transmission between the first conical body and the second conical body by extending along a third axis orthogonal to the two axes and contacting the first conical surface and the second conical surface. Is done.

The first axis, the second axis, and the third axis may intersect at one point, the first axis and the second axis may intersect at right angles, and the second axis and the third axis may intersect at right angles.

According to the joint mechanism according to the present invention, one joint can realize two or three degrees of freedom, so that the applied system can be configured with a small total number of joints, and the system can be made compact and lightweight. Becomes Further, since the number of joints can be suppressed, the number of arms between joints can be reduced, and the structure can be further simplified. In the joint mechanism, power is transmitted between the base cone (for example, a bevel gear), the intermediate cone and the tip cone, or power is transmitted between the first cone and the second cone, so that the joint mechanism is small and lightweight. is there. In addition, in the joint mechanism, since rotational power is directly transmitted between the base cone, the intermediate cone, and the tip cone, or between the first cone and the second cone, a transmission delay or the like occurs. It has excellent controllability and can operate with high precision. The motors in the joint mechanism need only electric wiring, and no wires or the like are required, so that they can be easily attached to the arm.

FIG. 1 is a schematic perspective view of a robot having a joint mechanism according to an embodiment of the present invention. FIG. 2 is a perspective view of the joint mechanism and its periphery according to the first embodiment. FIG. 3 is a side view of the joint mechanism and its periphery according to the first embodiment as viewed from a first direction. FIG. 4 is a side view of the joint mechanism according to the first embodiment and its periphery when viewed from a second direction. FIG. 5 is a cross-sectional view taken along the line V-V in FIG. FIG. 6 is an exploded perspective view of the joint mechanism according to the first embodiment. FIG. 7 is an exploded perspective view of the case, the base housing, the base board, and the tip housing. FIG. 8 is a perspective view showing the relative positional relationship between the tip housing and the case half. FIG. 9 is a perspective view showing a portion related to power transmission in the joint mechanism according to the first embodiment when the first axis and the third axis coincide with each other. FIG. 10 is a perspective view showing a part related to power transmission when the first axis and the third axis form an angle in the joint mechanism according to the first embodiment. FIG. 11 is a perspective view of the joint mechanism according to the second embodiment and its peripheral portion. FIG. 12 is a partially exploded perspective view of the joint mechanism according to the second embodiment. FIG. 13 is a side view of a portion related to power transmission in the joint mechanism according to the first modified example. FIG. 14 is a perspective view of a portion related to power transmission in the joint mechanism according to the first modified example. 15A is a skeleton diagram of a portion related to power transmission in the joint mechanism according to the second modification, and FIG. 15B is a skeleton portion of a portion related to power transmission in the joint mechanism according to the third modification. FIG. 15C is a skeleton diagram of a portion related to power transmission in the joint mechanism according to the fourth modification. FIG. 16 is a perspective view showing a portion related to power transmission in the joint mechanism according to the fifth modification when the first axis and the third axis form an angle.

Embodiments of a joint mechanism according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to this embodiment.

FIG. 1 is a schematic perspective view of a robot 12 including a joint mechanism 10A that is the first embodiment of the present invention and a joint mechanism 10B that is the second embodiment. The robot 12 is small and lightweight, and can be mounted on a small flying object such as a drone. The robot 12 may be a stationary type.

The robot 12 includes joint mechanisms 10A and 10B, three arms 14a, 14b and 14c, and a rod 16, and is controlled by the control unit 18. The arms 14a and 14b are cylindrical bodies. Although the arm 14c is also a cylinder, the inner cross section thereof has the same shape as the cross section of the rod 16, and has a rotation preventing function for the rod 16 and a retractable displacement guide function. The arm 14a is fixed to a predetermined pedestal portion. The length of the arms 14a to 14c does not matter.

A joint mechanism 10A is provided between the arms 14a and 14b. The joint mechanism 10A has a two-degree-of-freedom structure of turning and elevation as shown by arrows θα and θβ. A joint mechanism 10B is provided between the arms 14b and 14c. The joint mechanism 10B has a three-degree-of-freedom structure for turning, raising and lowering, and expanding and contracting the rod 16, as indicated by arrows θα, θβ, and Z. The rod 16 implements a linear motion mechanism by protruding and retracting from the tip of the arm 14c. An end effector 24 is provided at the tip of the rod 16. The end effector 24 is, for example, a camera. Next, the joint mechanism 10A according to the first embodiment will be described.

(First embodiment)
2 is a perspective view of the joint mechanism 10A and its periphery, FIG. 3 is a side view of the joint mechanism 10A and its periphery seen from a first direction, and FIG. 4 is a side view of the joint mechanism 10A and its periphery. It is the side view seen from 2 directions. Here, the first direction and the second direction are orthogonal to each other.

As shown in FIGS. 2 to 4, the joint mechanism 10A is covered with a case 26, a motor case 28, and a sensor cover 30. Further, a part of the joint mechanism 10A also enters the arms 14a and 14b. In the case 26, two case halves 26a and 26b are assembled face-to-face and substantially cover a portion between the arms 14a and 14b. The case half 26a and the case half 26b have substantially the same shape.

The motor case 28 has a cylindrical shape and slightly protrudes laterally. The sensor cover 30 has, for example, a dome shape having a spherical surface and slightly protrudes laterally. The motor case 28 and the sensor cover 30 are provided in opposite directions.

FIG. 5 is a cross-sectional view taken along the line V-V in FIG. FIG. 6 is an exploded perspective view of the joint mechanism 10A.

As shown in FIGS. 5 and 6, the joint mechanism 10A is roughly divided into a proximal end mechanism 32, an intermediate mechanism 34, and a distal end mechanism 36. The proximal end mechanism 32, the intermediate mechanism 34, and the distal end mechanism 36 are convenient divisions for easy understanding. For convenience of illustration, the intermediate mechanism 34 is shown separately in the upper and lower parts. Regarding the joint mechanism 10A, the direction of the arm 14a is the proximal end side, and the direction of the arm 14b is the distal end side. However, as will be described later, the names "tip" and "base" are for convenience.

The base end mechanism 32 includes a base end motor (first motor) 38, a base end gear head 40, a base end housing 42, a base end plate 44, and a base end gear body 46. Each of these members of the base end mechanism 32 is provided coaxially with the axis J1 (first axis) that is the center of the arm 14a. The base gear body 46 includes a base bevel gear (base cone) 50 and a pair of bearing posts 52. The tooth flank inclination of the base end bevel gear 50 is such that the diameter is reduced toward the tip end side. The pair of bearing posts 52 further protrude from the tip end surface of the base bevel gear 50 toward the tip.

The axis J1 is an axis along the extending direction of the arm 14a, but it does not need to be exactly coincident with the central axis of the arm 14a. The axis J3 described later is an axis along the extending direction of the arm 14b, but it does not have to be exactly coincident with the central axis of the arm 14b. It should be noted that the axis J1 is a solid reference line as shown as the center line, is not like the solid reference axis 60, and does not show one mechanical degree of freedom. The same applies to axes J2 and J3 described later.

The tip end surface of the base end plate 44 is fixed to the base end gear body 46. The base plate 44 has an annular groove 44a on its peripheral surface. The base end motor 38 rotates the base end plate 44 and the base end gear body 46 around the axis J1 via the base end gear head 40. An angle sensor (for example, a rotary encoder; the same applies hereinafter) is built in the base end motor 38, and the rotation angle of the base end bevel gear 50 can be detected. The base gear head 40 decelerates the rotation of the base motor 38 to rotate the base gear body 46. The base housing 42 has a bottomed cylindrical shape in which the tip surface other than the shaft hole is closed, and an annular groove 42a is provided on the peripheral surface. The proximal housing 42 is housed inside the arm 14a on the proximal side of the annular groove 42a, and is covered by the case 26 on the distal side of the annular groove 42a. The base motor 38 and the base gear head 40 are housed and fixed inside a base housing 42. The base housing 42 is fixed to the arm 14a.

The intermediate mechanism 34 is a relay portion between the base end mechanism 32 and the tip end mechanism 36, and includes an intermediate motor (second motor) 54, an intermediate plate 56, an intermediate bevel gear (intermediate conical body) 58, and a reference shaft 60. , A plate 62, an angle sensor 64, and a circuit board 66. Each of these members in the intermediate mechanism 34 is provided coaxially with the axis J2 (second axis). The axis J2 is orthogonal to the axis J1 and passes through the bearing holes of the pair of bearing posts 52 and 78. The arm 14a and the arm 14b are relatively rotatable around the reference shaft 60.

The intermediate motor 54, the intermediate disk 56, and the intermediate bevel gear 58 are provided above the shaft J1 and the shaft J3 in FIGS. 5 and 6, and the plate 62, the angle sensor 64, and the circuit board 66 are located above the shaft J1 and the shaft J3. It is provided on the lower side.

The inclination of the tooth flank of the intermediate bevel gear 58 is such that the diameter decreases as it approaches the axis J1 and the axis J3. The end face of the intermediate plate 56 is fixed to the intermediate bevel gear 58. The intermediate motor 54 rotates the intermediate plate 56 and the intermediate bevel gear 58 around the axis J2. The intermediate motor 54 has a speed reduction mechanism built therein. The intermediate motor 54 may rotate the intermediate bevel gear 58 without a reduction mechanism as long as it is of a large output type. The intermediate motor 54 is housed and fixed in the motor case 28, and only the rotating shaft projects and is connected to the intermediate plate 56. The motor case 28 covers the intermediate motor 54 with a main body of a bottomed cylinder and a lid 28a provided on the outside.

The reference shaft 60 is rotatably supported by a pair of bearing posts 52, and non-rotatably connects the upper intermediate bevel gear 58 and the lower angle sensor 64. A plate 62 is interposed between the bearing post 52 and the angle sensor 64. An electric circuit for the angle sensor 64 is formed on the circuit board 66. The angle sensor 64 and the circuit board 66 are covered with the sensor cover 30 on the outside.

The tip mechanism 36 includes a tip motor (third motor) 68, a tip gear head 70, an O-ring 72, a tip housing 74, a tip bevel gear (tip cone) 76, and a bearing post 78. Each of these members in the tip mechanism 36 is provided coaxially with the axis J3 (third axis) that is the center of the arm 14b. The axis J3 and the axis J2 are orthogonal to each other. The angle θβ formed by the axis J1 and the axis J3 (see FIG. 10) is variable.

The tooth flank inclination of the tip bevel gear 76 is such that the diameter is reduced toward the base end side. A bearing post 78 is fixed to the base end side surface of the tip bevel gear 76. The bearing post 78 projects toward the base end side, and is interposed between the pair of bearing posts 52 to pivotally support the reference shaft 60.

The base end surface of the tip bevel gear 76 is fixed to the tip surface of the bearing post 78. The tip motor 68 rotates the tip bevel gear 76 about the axis J3 via the tip gear head 70. Further, as will be described later, any one of the base end motor 38, the intermediate motor 54 and the tip end motor 68 may be omitted. The tip motor 68 has a built-in angle sensor and can detect the rotation angle of the tip bevel gear 76.

The tip gear head 70 decelerates the rotation of the tip motor 68 to rotate the tip bevel gear 76. The tip housing 74 has a bottomed cylindrical shape in which the base end side surface other than the shaft hole is closed, and an annular groove 74a is provided on the peripheral surface. Further, the tip housing 74 has a short cylinder portion 74b at the base end portion, and an arc plate 74c provided at the base end of the short cylinder portion 74b via a short connecting portion 74d. The annular groove 74a is provided adjacent to the short tubular portion 74b. The tip housing 74 is housed inside the arm 14b on the tip side of the annular groove 74a. The tip motor 68 and the tip gear head 70 are housed and fixed inside the tip housing 74. The O-ring 72 is fitted in the annular groove 74a and pressed by the inner peripheral surface of the arm 14b to be elastically deformed, and has a sealing action. The tip housing 74 is fixed to the arm 14b.

FIG. 7 is an exploded perspective view of the case 26, the base housing 42, the base board 44, and the front housing 74. FIG. 8 is a perspective view showing a relative positional relationship between the tip housing 74 and the case half body 26a.

As shown in FIG. 7, the case half 26a of the case 26 includes a tubular body 80 centered on the axis J2, a side plate 82 that substantially covers the lateral side of the tubular body 80, and a direction along the axis J1 direction from the tubular body 80. And a half cylinder 84 protruding toward the base end side. Two semi-annular protrusions 84 a and 84 b are provided on the inner peripheral surface of the half cylinder 84. The semi-annular protrusion 84a is provided at a position close to the tubular body 80, and the semi-annular protrusion 84b is provided at the base end portion.

As described above, the case halves 26a and the case halves 26b have substantially the same shape, and by being combined with each other, the pair of cylindrical bodies 80 form the slit 85 (see FIGS. 2 and 3) therebetween. The width of the slit 85 is substantially equal to the width of the connecting portion 74d of the tip housing 74. Further, the pair of half cylinders 84 forms one cylinder, and the pair of semi-annular projections 84a and the pair of semi-annular projections 84b form continuous inward annular projections. The base plate 44 is positioned by fitting the pair of semi-annular projections 84a into the annular groove 44a. The pair of semi-annular projections 84b are fitted into the annular groove 42a to be positioned and slidable with respect to the proximal housing 42, and the pair of semi-cylindrical 84 combined is rotatable about the axis J1. ..

As shown in FIG. 8, the circular arc plate 74c of the distal housing 74 extends parallel to the axis J2, and the proximal end side forms a flat surface and the distal end side forms an arcuate surface 74ca. The arc surface 74ca has a convex shape toward the tip side. An arc surface 74ba facing the arc surface 74ca is formed on the base end side of the short tubular portion 74b. The arc surface 74ba has a concave shape. The arcuate surface 74ba and the arcuate surface 74ca form a gap 74e. The gap 74e is provided on both sides of the connecting portion 74d as a center. The width of the gap 74e is substantially equal to the thickness of the tubular body 80.

The case half 26a becomes slidable around the axis J2 by fitting a part of the tubular body 80 into the one gap 74e. The same applies to the case half 26b. The connection portion 74d is sandwiched by a slit 85 (see FIGS. 2 and 3) formed between the pair of cylindrical bodies 80 and is stabilized.

As shown in FIG. 9, the axis J1 and the axis J2 are orthogonal to each other, and the axis J2 and the axis J3 are orthogonal to each other. The axis J1, the axis J2, and the axis J3 intersect at one point of the joint center O. In the present application, a state in which the axis J1 and the axis J3 coincide with each other as shown in FIG.

The teeth of the base bevel gear 50 are formed along a conical surface with the axis J1 as a reference. The teeth of the intermediate bevel gear 58 are formed along a conical surface with the axis J2 as a reference. The teeth of the tip bevel gear 76 are formed along a conical surface with the axis J3 as a reference. The three base-end bevel gears 50, the intermediate bevel gear 58, and the tip bevel gear 76 have the same shape. Therefore, the diameter (for example, the reference circle diameter, the same applies hereinafter), the number of teeth, and the modules are the same. Since the base bevel gear 50, the intermediate bevel gear 58, and the tip bevel gear 76 have the same shape, they can be arranged compactly around the joint center O without waste.

The base bevel gear 50 and the intermediate bevel gear 58 mesh with each other, and the intermediate bevel gear 58 and the tip bevel gear 76 mesh with each other. In FIG. 9, the base bevel gear 50 and the intermediate bevel gear 58 mesh with each other at a meshing portion 86 shown by a broken line frame, and the intermediate bevel gear 58 and the tip bevel gear 76 mesh with each other at a meshing portion 88.

In the description here, the side on which the base motor 38 is provided is the base side (that is, the arm 14a side), and the side on which the tip motor 68 is provided is the tip side (that is, the arm 14b side). As is clear from FIG. 9, the joint mechanism 10A can be applied even if the front end side and the base end side are reversed. That is, the names “tip” and “base” in the joint mechanism 10A are for convenience of specifying the direction. The same applies to the joint mechanism 10B.

When the joint mechanism 10A starts to operate from the reference posture, the teeth near the meshing portions 86 and 88 tend to be used frequently, which is a heavy burden, although it depends on the operation mode. Therefore, in the joint mechanism 10A, under the action of the control unit 18, the teeth of the meshing portions 86 and 88 are shifted at a predetermined timing (every time at startup, every fixed time period, or timing included in normal operation) that has little influence on the operation. It is processing. For example, when the base end motor 38 rotates the base end bevel gear 50 by 90° in the predetermined direction and the intermediate motor 54 rotates the intermediate bevel gear 58 by 90° in the predetermined direction, the broken line frame 90 and the broken line frame 92 are newly added. It becomes the meshing portion 88. When the tip motor 68 rotates the tip bevel gear 76 by 90° in a predetermined direction, some of the teeth of the intermediate bevel gear 58 and the tip bevel gear 76 in the depth direction of the paper in FIG. 9 become new meshing portions 88. .. At this time, the relative positions of the base motor 38, the intermediate motor 54, and the tip motor 68 do not change, and the relative positions of the arms 14a and 14b do not change and the reference posture is maintained. In the process of shifting the teeth of the meshing portions 86 and 88, the rotation angle of each bevel gear is not limited to 90°, but may be shifted by one tooth, for example.

In this way, in the joint mechanism 10A, it is possible to prevent only certain teeth from being biased and used excessively, and the reliability of the base bevel gear 50, the intermediate bevel gear 58, and the tip bevel gear 76 is enhanced, and the life is extended. Since the tooth load of the base bevel gear 50, the intermediate bevel gear 58, and the tip bevel gear 76 is reduced, these may be made of resin.

As shown in FIG. 10, the arm 14b is capable of elevation motion by rotating around the axis J2. In FIG. 10, the elevation motion is indicated by an angle θβ formed by the axis J1 and the axis J3. In the elevation motion, when the intermediate motor 54 rotates the intermediate bevel gear 58, the tip bevel gear 76 and the arm 14b are rotationally displaced about the axis J2 while the meshing of the meshing portion 88 (see FIG. 9) is maintained. Since the rotation of the intermediate bevel gear 58 is also transmitted to the base bevel gear 50, the intermediate bevel gear 58 rotates about the axis J1 when the base bevel gear 50 is stopped. In other words, the arm 14b turns with the intermediate bevel gear 58 about the axis J1 by the angle θα.

When only the elevation motion is performed without performing the turning motion, the base bevel gear 50 may be rotated by the base motor 38 so as to cancel the rotation of the intermediate bevel gear 58. When only the turning motion is performed without performing the elevation motion, if only the base bevel gear 50 is rotated while the intermediate bevel gear 58 is stopped, the arm 14b is rotationally displaced about the axis J1. When the turning motion and the elevation motion are performed simultaneously, the base bevel gear 50 and the intermediate bevel gear 58 may be cooperatively rotated.

In the elevation motion indicated by the angle θβ, the tip bevel gear 76 rotates about the axis J2 while keeping the mesh state with the intermediate bevel gear 58. In this case, since the tip bevel gear 76 can be rotationally displaced until it comes into contact with the base bevel gear 50, the operating range of the angle θβ is ±90° with reference to the axis J1. The angle θα can be rotated endlessly.

As described above, basically, the turning motion and the elevation motion can be realized only by the two of the base end motor 38 and the intermediate motor 54, but either one of them can be replaced by the tip end motor 68.

That is, when the tip end motor 68 replaces the intermediate motor 54, the tip end motor 68 causes the tip end bevel gear 76 to rotate, whereby the elevation motion can be realized. The turning operation can be realized by rotating the base bevel gear 50 by the base motor 38 as described above.

Further, when the tip end motor 68 replaces the base end motor 38, the elevation motion can be realized by rotating the tip bevel gear 76 by the tip motor 68 as described immediately above. Regarding the turning operation, if the intermediate bevel gear 58 is rotated by the intermediate motor 54, the base bevel gear 50 is stopped, so that the intermediate bevel gear 58 rotates with the arm 14b about the axis J1 at an angle θα. Since the intermediate bevel gear 58 is also meshed with the tip bevel gear 76, if the tip bevel gear 76 is stopped, the arm 14b also performs the elevation motion about the axis J2, but the pivot motion does not occur. In the case of performing only the above, the tip bevel gear 76 may be rotated by the tip motor 68 so as to cancel the rotation of the intermediate bevel gear 58.

As described above, in the joint mechanism 10A, since only two of the proximal end motor 38, the intermediate motor 54, and the distal end motor 68 can realize the turning motion and the elevation motion, if any one of them fails. The remaining two motors can continue to operate. Further, the load can be reduced by performing the rotation operation in which one of the three motors is regularly stopped. Further, all of the base end motor 38, the intermediate motor 54, and the tip end motor 68 may be used to cooperatively realize the turning motion and the elevation motion.

(Second embodiment)
Next, the joint mechanism 10B according to the second embodiment will be described. In the joint mechanism 10B, the same parts as those in the joint mechanism 10A are designated by the same reference numerals, and detailed description thereof will be omitted.

11 is a perspective view of the joint mechanism 10B and its peripheral portion, and FIG. 12 is a partially exploded perspective view of the joint mechanism 10B. In FIGS. 11 and 12, the case 26 and the tip housing 74 are omitted so that the internal mechanism of the joint mechanism 10B can be visually recognized.

In the description of the joint mechanism 10B, the direction of the arm 14b is the proximal end side, and the direction of the arm 14c is the distal end side. Further, the center of the arm 14b and the base end motor 38 is the axis J1, the center of the intermediate motor 54 and the reference shaft 60 is the axis J2, and the center of the arm 14c and the rod 16 is the axis J3. Further, the rotation of the arm 14c about the axis J1 is referred to as a turning operation, and the rotation about the axis J2 is referred to as a elevation operation. As described above, the joint mechanism 10B has a three-degree-of-freedom structure for turning, raising and lowering, and expanding and contracting the rod 16 as shown by arrows θα, θβ, and Z.

In the joint mechanism 10B, the base end mechanism 32 (see FIG. 6) and the intermediate mechanism 34 (see FIG. 6) in the joint mechanism 10A described above have the same configuration. In the joint mechanism 10B, an O-ring 72, a tip housing 74, a tip bevel gear 76, and a bearing post 78 are provided among the components of the tip mechanism 36 in the joint mechanism 10A, and the tip motor 68 and the tip gear head 70 are omitted. There is.

As shown in FIG. 11, the joint mechanism 10B is provided with a linear motion mechanism 93. The linear motion mechanism 93 is a mechanism that moves the rod 16 in and out of the arm 14c to move the rod 16 back and forth in the Z direction. The Z direction coincides with the direction of the axis J3.

As shown in FIG. 12, the linear motion mechanism 93 has a screw (male screw portion) 94 and a rod (female screw portion) 16. The arm 14c is also a part of the linear motion mechanism 93. The screw 94 and the rod 16 have substantially the same length as the arm 14c, for example. The screw 94 is a long screw member, and the base end side is fixed to the tip side surface of the tip bevel gear 76 by a fixing tool 96. The screw 94 extends along the axis J3.

The rod 16 is a long member having an internal thread formed on its inner surface, and has a cylindrical surface and a pair of upper and lower flat surfaces 16a. The flat surface 16a is formed over the entire length of the rod 16 along the direction of the axis J3. The rod 16 is screwed onto the screw 94.

A pair of upper and lower flat surfaces 14ac are provided on the inner surface of the arm 14c. The plane 14ac is formed over the entire length of the arm 14c along the direction of the axis J3. The rod 16 is fitted inside the arm 14c, and the pair of flat surfaces 16a and the pair of flat surfaces 14ac contact each other. This restricts the rod 16 from rotating around the axis J3 and enables smooth displacement in the direction of the axis J3. The end portion of the arm 14c is fixed to a part of the tip housing 74 (see FIG. 6).

In such a joint mechanism 10B, similar to the joint mechanism 10A described above, the rotation of the base bevel gear 50 by the base motor 38 and the rotation of the intermediate bevel gear 58 by the intermediate motor 54 cause the arm 14c to pivot and lift. Can be realized. That is, the turning angle θα can be freely set, and the elevation angle θβ can be freely set within a range of ±90°.

On the other hand, when the base bevel gear 50 and the intermediate bevel gear 58 are respectively rotated in the predetermined directions by the same angle in any posture, the tip bevel gear 76 can be rotated while maintaining the angles θα and θβ. .. Then, the screw 94 rotates integrally with the tip bevel gear 76 around the axis J3, so that the rod 16 screwed into the screw 94 advances and retreats along the axis J3. In this way, the linear motion of the linear motion mechanism 93 is realized. Of course, two or more of the angle θα, the angle θβ, and the displacement Z may be simultaneously operated. In the linear motion mechanism 93, a female screw portion corresponding to the rod 16 may be rotated and a male screw portion corresponding to the screw 94 may be advanced and retracted. That is, the linear motion mechanism 93 is composed of a male screw portion and a female screw portion that are screwed together, and the rotation of one moves the other forward or backward.

According to the joint mechanisms 10A and 10B described above, one joint can realize two or three degrees of freedom, and therefore the applicable robot 12 can be configured with a small total number of joints. It is small and lightweight. Further, since the number of joints can be suppressed, the number of arms between joints can be reduced, and the structure can be further simplified.

The joint mechanisms 10A and 10B have excellent controllability and high-precision operation without transmission delay because the rotational power is directly transmitted between the base bevel gear 50, the intermediate bevel gear 58, and the tip bevel gear 76. Is possible. The motors in the joint mechanisms 10A and 10B need only electric wiring, and no wires or the like are required, so that they can be easily attached to the arms 14a to 14c. The joint mechanisms 10A and 10B have a simple structure and low cost. By using MEMS (Micro Electro Mechanical Systems) for the joint mechanisms 10A and 10B, it is possible to further reduce the size.

Since the base bevel gear 50, the intermediate bevel gear 58, and the tip bevel gear 76 are bevel gears, teeth are formed along the respective conical surfaces, but in a broad sense, the conical surfaces abut each other. It can be said that power is being transmitted. This is because, for example, the same power transmission is possible even with a conical friction plate having no teeth. Therefore, it can be said that the base bevel gear 50, the intermediate bevel gear 58, and the tip bevel gear 76 in the present application are examples of a conical body (including a truncated cone; the same applies hereinafter).

In addition, the base bevel gear 50, the intermediate bevel gear 58, and the tip bevel gear 76 do not necessarily need to have teeth formed on the entire circumference, and depending on the specifications and conditions, teeth are formed only in a limited range of motion. May be. As described above, the base bevel gear 50, the intermediate bevel gear 58, and the tip bevel gear 76 can be regarded as an example of a conical body even when the teeth are formed only at a predetermined angle.

(Modification)
Next, joint mechanisms 10C, 10D, 10E, 10F and 10G according to modified examples of the joint mechanisms 10A and 10B will be described. In the description of the joint mechanisms 10C to 10G, the same parts as those of the joint mechanisms 10A and 10B are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 13 is a side view of a portion related to power transmission in the joint mechanism 10C according to the first modification, and FIG. 14 is a perspective view of a portion related to power transmission in the joint mechanism 10C.

As shown in FIGS. 13 and 14, the base bevel gear 50 and the tip bevel gear 76 in the joint mechanism 10C are the same as those in the joint mechanisms 10A and 10B, but the intermediate bevel gear 58 is different. In the joint mechanisms 10A and 10B, the three bevel gears 50, the tip bevel gears 76, and the intermediate bevel gears 58 have the same diameter and the same number of teeth, but the intermediate bevel gears 58 in the joint mechanism 10C have the proximal bevel gears 50. The diameter and the number of teeth are set to be twice as large as those of the tip bevel gear 76.

Therefore, as shown in FIG. 13, the distance between the base bevel gear 50 and the tip bevel gear 76 is slightly long, but the side surface area of the intermediate bevel gear 58 is large, and the intermediate motor 54 is flattened accordingly. be able to. Therefore, the intermediate motor 54 can suppress the amount of protrusion in the direction of the axis J2 while having a volume required to secure a predetermined output.

Further, as shown in FIG. 14, the arm 14b performs the elevation motion about the reference shaft 60, but the operating range of the angle θβ is limited to the position where the tip bevel gear 76 contacts the base bevel gear 50. In the joint mechanism 10C, since the intermediate bevel gear 58 has a larger diameter than the base bevel gear 50 and the tip bevel gear 76, a wide operating range is secured, and the operating range of the angle θβ is approximately ±130°.

FIG. 15A is a skeleton diagram of a portion related to power transmission in the joint mechanism 10D according to the second modification. In the joint mechanism 10D, the axis J1, the axis J2, and the axis J3 intersect at one point of the joint center O, but the angle between the axis J1 and the axis J2 and the angle between the axis J2 and the axis J3 are not 90°. Depending on the specifications and design conditions, the intersection angle between the axes may be an acute angle or an obtuse angle, as in the joint mechanism 10D.

FIG. 15B is a skeleton diagram of a portion related to power transmission in the joint mechanism 10E which is the third modified example. In the joint mechanism 10E, the angle between the axis J1 and the axis J2 and the angle between the axis J2 and the axis J3 are 90°, respectively. Does not match O2. Depending on the specifications and design conditions, like the joint mechanism 10E, the axis J1, the axis J2, and the axis J3 do not necessarily have to intersect at one point.

Like the joint mechanisms 10A and 10B, the above-described joint mechanisms 10C to 10E can achieve two degrees of freedom if two or more of the base motor 38, the intermediate motor 54, and the tip motor 68 are provided, If three are provided, any one can be used for backup. Further, as in the joint mechanism 10B, the joint mechanisms 10C to 10E can realize three degrees of freedom by providing the linear motion mechanism 93 instead of the tip motor 68.

FIG. 15C is a skeleton diagram of a portion related to power transmission in the joint mechanism 10F according to the fourth modified example. In the joint mechanism 10F, two intermediate bevel gears 58a and 58b are provided between the base end bevel gear 50 and the tip bevel gear 76. The intermediate bevel gear 58a has a conical surface with the axis J2a as a reference, and is rotated by the intermediate motor 54a. The intermediate bevel gear 58b has a conical surface with the axis J2b as a reference, and is rotated by the intermediate motor 54b. The axis J1, the axis J2a, the axis J2b, and the axis J3 intersect at one point of the joint center O. The axis J1 and the axis J2 are arranged in a straight line in a standard posture.

Similar to the joint mechanisms 10A and 10B, the joint mechanism 10F can achieve two degrees of freedom if two or more of the base end motor 38, the intermediate motors 54a and 54b, and the tip end motor 68 are provided, and three joints are provided. Alternatively, if four are provided, either one or two can be used for backup. Further, the joint mechanism 10F can realize three degrees of freedom by providing the linear motion mechanism 93 instead of the distal end motor 68 or the proximal end motor 38, similarly to the joint mechanism 10B. Further, if three or more of the base end motor 38, the intermediate motors 54a and 54b, and the tip end motor 68 are provided, the arm 14b along the axis J2b is provided in addition to the arm 14b along the axis J3. 'Can be operated semi-independently with respect to the arm 14b.

FIG. 16 is a perspective view showing a portion related to power transmission in the joint mechanism 10G according to the fifth modification when the first axis and the third axis form an angle. In FIG. 16, the bearing post 52 and a part of the reference shaft 60 are omitted. The joint mechanism 10G has a two-degree-of-freedom structure capable of turning and raising/lowering motions as indicated by arrows θα and θβ.

In the joint mechanism 10G, the proximal end mechanism 32 (see FIG. 6) in the above-mentioned joint mechanism 10A has the same configuration. In the joint mechanism 10G, the intermediate mechanism 34 in the joint mechanism 10A has the same configuration, but the reference shaft 60 has a detent portion 60a having a non-circular cross section formed in the intermediate portion (a position including the joint center O). Has been done.

In the joint mechanism 10G, a post 98 is provided at a position corresponding to the bearing post 78 in the tip mechanism 36 of the joint mechanism 10A, and the rest is omitted. The post 98 is interposed between the pair of bearing posts 52 similarly to the bearing post 78 described above, but since the detent portion 60a is fitted into the detent hole 98a having a non-circular cross section, the bearing function is achieved. Instead, it rotates integrally with the reference shaft 60 and the intermediate bevel gear (second conical body) 58. The rotation stopping portion 60a and the rotation stopping hole 98a have the same shape in cross section, and cannot rotate relative to each other due to a pair of parallel surfaces contacting each other like the rod 16 and the arm 14c (see FIG. 12). The post 98 is fixed to the arm 14b. In this case, a pair of auxiliary arc pieces 100 may be attached to the flat surface portion of the reference shaft 60 at a portion fitted into the shaft hole of the bearing post 52. The pair of auxiliary arc pieces 100 has a circular shape that complements the cross-sectional shape of the reference shaft 60, and is easily supported by the bearing post 52.

In such a joint mechanism 10G, by rotating the intermediate bevel gear 58 and the reference shaft 60 around the axis J2 under the action of the intermediate motor 54, the arm 14b rotates integrally with them. That is, the elevation motion is performed as indicated by the angle θβ. Since the rotation of the intermediate bevel gear 58 is also transmitted to the base bevel gear (first conical body) 50, the intermediate bevel gear 58 rotates about the axis J1 when the base bevel gear 50 is stopped. .. In other words, the arm 14b turns with the intermediate bevel gear 58 about the axis J1 by the angle θα.

When only the elevation motion is performed without performing the turning motion, the base bevel gear 50 may be rotated by the base motor 38 so as to cancel the rotation of the intermediate bevel gear 58. When only the turning motion is performed without performing the elevation motion, if only the base bevel gear 50 is rotated while the intermediate bevel gear 58 is stopped, the arm 14b is rotationally displaced about the axis J1. When the turning motion and the elevation motion are performed simultaneously, the base bevel gear 50 and the intermediate bevel gear 58 may be cooperatively rotated. In the joint mechanism 10G, as in the joint mechanism 10C (see FIG. 13), the intermediate bevel gear 58 may have a larger diameter and a larger number of teeth than the base bevel gear 50.

The present invention is not limited to the above-described embodiments, and it goes without saying that the present invention can be freely modified without departing from the gist of the present invention.

10A, 10B, 10C, 10D, 10E, 10F, 10G Joint mechanism 12 Robots 14a, 14b, 14b', 14c Arm 16 Rod (female screw part)
18 Control Unit 24 End Effector 26 Case 32 Base End Mechanism 34 Intermediate Mechanism 36 Tip End Mechanism 38 Base End Motor (First Motor)
46 base end gear body 50 base end bevel gear (base end conical body, first conical body)
54 Intermediate motor (second motor)
58 Intermediate bevel gear (intermediate conical body, second conical body)
60 Reference shaft 68 Tip motor (third motor)
76 Tip bevel gear (tip cone)
93 Direct Acting Mechanism 94 Screw (Male Thread)
J1 axis (1st axis)
J2 axis (second axis)
J3 axis (3rd axis)
O Joint center Z displacement θα, θβ angle

Claims (9)

A joint mechanism provided between two arms,
A base conical body rotatable about a first axis along one arm with an axis applied to the first conical surface;
An intermediate cone that is rotatable about a second axis on the second conical surface;
A tip cone that is rotatable about a third axis along the other arm with the axis of the third conical surface;
And further,
A first motor provided on the one arm, wherein the base cone is rotated about the first axis;
A second motor for rotating the intermediate cone about the second axis;
A third motor provided on the other arm, which rotates the tip cone about the third axis;
With two of them,
The one arm and the other arm are configured to be relatively rotatable about a reference axis,
When the first conical surface and the second conical surface are in contact with each other, power is transmitted between the base conical body and the intermediate conical body,
A joint mechanism characterized in that power is transmitted between the intermediate cone and the base cone by contact between the second cone surface and the third cone surface. The joint mechanism according to claim 1,
A joint mechanism comprising three of the first motor, the second motor, and the third motor. A joint mechanism provided between two arms,
A base conical body rotatable about a first axis along one arm with an axis applied to the first conical surface;
An intermediate cone that is rotatable about a second axis on the second conical surface;
A tip cone that is rotatable about a third axis along the other arm with the axis of the third conical surface;
A first motor provided on the one arm, wherein the base cone is rotated about the first axis;
A second motor that rotates the intermediate cone about the second axis;
A linear motion mechanism that expands and contracts based on the tip cone rotating around the third axis,
Equipped with
The one arm and the other arm are configured to be relatively rotatable around a reference axis,
When the first conical surface and the second conical surface are in contact with each other, power is transmitted between the base conical body and the intermediate conical body,
A joint mechanism characterized in that power is transmitted between the intermediate cone and the base cone by contact between the second cone surface and the third cone surface. The joint mechanism according to claim 3,
The joint mechanism, wherein the linear motion mechanism includes a male screw portion and a female screw portion that are screwed together, and one of the male screw portion and the female screw portion is rotated to move the other forward or backward. The joint mechanism according to any one of claims 1 to 4,
The joint mechanism, wherein the base cone, the intermediate cone, and the tip cone have the same diameter. The joint mechanism according to any one of claims 1 to 4,
The proximal cone and the distal cone have the same diameter,
The joint mechanism, wherein the intermediate cone has a larger diameter than the proximal cone and the distal cone. The joint mechanism according to any one of claims 1 to 6,
At a predetermined timing, the contact position between the base cone and the intermediate cone in the reference posture is shifted, and the contact position between the intermediate cone and the tip cone in the reference posture is shifted. A joint mechanism having a control unit for controlling. A joint mechanism provided between two arms,
A first conical body rotatable about a first axis along one arm with an axis applied to the first conical surface;
A second conical body rotatable about a second axis applied to the second conical surface;
A first motor provided on the one arm, wherein the first cone is rotated about the first axis;
A second motor for rotating the second cone about the second axis;
Equipped with
The other arm is provided rotatably around the second axis together with the second cone, and extends along a third axis orthogonal to the second axis,
A joint mechanism characterized in that power is transmitted between the first conical body and the second conical body by contact between the first conical surface and the second conical surface. The joint mechanism according to any one of claims 1 to 4,
The first axis, the second axis and the third axis intersect at one point,
The first axis and the second axis are orthogonal to each other,
The joint mechanism, wherein the second axis and the third axis are orthogonal to each other.

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