JP2015123509A - Robot joint structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and extend a life of a joint structure.SOLUTION: A joint structure is equipped with a first rotator 8 which rotates about a first rotary axis S1 intersecting a joint shaft A5 to a base side arm member 4a, and a second rotator 9 which rotates about a second rotary axis A2 intersecting the first rotary axis A1 and tilted to the first rotary axis A1 to the first rotator 8 while rotating with the first rotator 8. The second rotator 9 includes an output portion 10 which extends from an intersection point of the two rotary axes A1 and A2 along an extension shaft A3 tilted to the second rotary axis A2, and engages with a tool side arm member 4b. The second rotator 9 rotates about the second rotary axis A2 to the first rotator 8 while rotating about the first rotary axis A1 to the base side arm member 4a, so that the output portion 10 and the tool side arm member 4b supporting the output portion 10 carry out rotational movement about a joint shaft A5 to the base side arm member 4a.

Description

  The present invention relates to a joint structure of a robot in which a tool-side arm member is rotatably connected to a base-side arm member around a predetermined joint axis.

  In the joint structure of the robot, the rotational driving force generated by the rotational driving source is transmitted to the tool-side arm member via the reduction gear. For example, as shown in Patent Document 1, the speed reducer is interposed between a base end side arm member and a tip end side arm member, and an output element of the speed reducer is coaxial with the tool side arm member and is on the tool side. It rotates by the same rotation angle as the arm member.

JP 2009-166219 A

  When the weight of the tool, the weight and length of the arm member are increased, the torque necessary for maintaining the posture of the arm member and the torque necessary for accelerating the tool side arm member at the time of starting, etc. are naturally increased. If this is not addressed, the life of the reduction gear (for example, the bearing life of the reduction gear) is shortened. If the configuration of the speed reducer described above is maintained, in order to avoid shortening the service life of the speed reducer, the cost of the speed reducer can be increased, as well as increasing the size of the speed reducer. The balance between the life of the reduction gear and the size and cost leads to restrictions on the performance of the robot.

  Accordingly, an object of the present invention is to provide a joint structure that is reduced in size and extended in life.

  A joint structure of a robot according to an aspect of the present invention is a joint structure of a robot that connects a tool-side arm member to a base-side arm member so as to be rotatable around a joint axis, and the base-side arm member A first rotating body that rotates about a first rotation axis that intersects the joint axis, and the first rotating body that intersects the first rotation axis while rotating together with the first rotating body. A second rotating body that rotates around a second rotation axis that is inclined to the first rotation axis. The second rotating body extends along an extending axis inclined from the intersection of the first rotating axis and the second rotating axis to the second rotating axis and engages with the arm member on the tool side. including. The second rotating body rotates around the second rotation axis with respect to the first rotating body while rotating around the first rotation axis with respect to the arm member on the base side, so that the output unit and The arm member on the tool side engaged therewith rotates relative to the arm member on the base side around the joint axis.

  According to the above-described configuration, the first rotating body and the second rotating body operate as described above, so that the tool-side arm member rotates around the joint axis with respect to the base-side arm member as in the conventional joint structure. Can be realized. These first rotating body and second rotating body constitute a mechanical speed reducer. In other words, the second rotating body includes an output portion extending along the extending axis, and this output portion engages with the arm member on the tool side and rotates and moves around the joint axis together with the arm member. The second rotation axis is inclined with respect to the first rotation axis, the extension axis, and the joint axis, and the apparent length (rotation radius) of the arm member on the tool side viewed from the second rotation body according to the inclination. ) Becomes shorter. For this reason, even when the weight of the tool, the actual length of the tool side arm member, the weight, and the inertia ratio are the same as those of the conventional joint structure, the posture of the tool side arm member is maintained as compared with the conventional joint structure. Torque and torque around the second rotation axis of the second rotating body necessary for accelerating the tool side arm member are reduced. Accordingly, the first and second rotating bodies and the components (for example, bearings) provided in the periphery thereof can be made smaller and have a longer life than the speed reducer in the conventional joint structure.

  According to the present invention, it is possible to realize a long life while maintaining a small size.

It is a conceptual diagram of the robot to which the joint structure which concerns on embodiment is applied. (A) is a figure which shows the robot arm to which the joint structure which concerns on embodiment is applied. (B) is a figure which shows the robot arm to which the joint structure which concerns on a comparative example is applied. It is operation | movement explanatory drawing of the joint structure which concerns on embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a robot 1 to which the joint structure according to the embodiment is applied. The robot 1 has a base 2 and a movable robot arm 3. The robot arm 3 has a plurality of arm members 4 sequentially connected from the base 2 (note that the number of arm members 4 shown in the figure is merely an example). A tool 50 corresponding to the work required for the robot 1 is detachably attached to the tip of the arm member 4c farthest from the base 2 (that is, the tip of the robot arm 3). Joints 5 are provided between the base 2 and the lower arm member 4a connected to the base 2 and between the two adjacent arm members 4 and 4, respectively. The joint 5 rotatably connects the tool side member to the base side member.

  The joint structure according to the present embodiment is employed in, for example, the joint 5b that connects the upper arm member 4b to the lower arm member 4a. However, the joint structure can be used for the other joints 5a and 5c, and can also be used for joints of robot arms different from those shown in FIG.

  FIG. 2A is a diagram illustrating a joint structure according to the embodiment, and FIG. 2B is a diagram illustrating a joint structure according to a comparative example. In either case, the tool side arm member (arm member 4b or 94b) can swing around the joint axis A5 or 9A5 with respect to the base side arm member (arm member 4a or 94a). Both the joint axes A5 and A95 both extend in the direction intersecting the vertical direction, for example, in the horizontal direction. In the following description, unless otherwise specified, the weight and the inertial performance ratio of the tool and the arm member are the same in the embodiment and the comparative example.

  In the comparative example, the distal end portion of the arm member 94a on the base side overlaps with the proximal end portion of the arm member 94b on the tool side in the joint axis direction. The rotational driving force of the motor 96 is transmitted to the arm member 94b via the input element and the output element of the speed reducer 97. The output element of the speed reducer 97 is coaxial with the arm member 94b (that is, around the joint axis A95) and rotates by the same rotation angle as the arm member 94b.

  The joint structure according to the embodiment includes a rotation mechanism 7 and a rotation drive source 6 that drives the rotation mechanism 7. The rotation drive source 6 may be configured in any way as long as it can drive the rotation mechanism 7, and is configured by an electric motor as an example.

  The rotating mechanism 7 rotates with the first rotating body 8 around the first rotating axis A1 intersecting the joint axis A5 with respect to the base side arm member 4a, and rotates together with the first rotating body 8 for the first rotation. And a second rotating body 9 that rotates around a second rotating axis A2 that intersects the first rotating axis A1 and is inclined to the first rotating axis A1 with respect to the body 8. The first rotating body 8 includes a rotating shaft portion 10 that is rotatably supported around the first rotating axis A1 by the base side arm member 4a. The 2nd rotary body 9 contains the output part 11 engaged with the arm member 4b of the front end side. The output unit 11 extends along an extending axis A3 inclined from the intersection of the first rotation axis A1 and the second rotation axis A2 to the second rotation axis A2. The output portion 11 is rotatably supported around the extending axis A3 by the arm member 4b on the distal end side.

  When the first rotating body 8 rotates around the first rotation axis A1 with respect to the arm member 4a on the base side, the second rotating body 9 is first moved with respect to the arm member 4a on the base side. It rotates by the same rotation angle as the first rotating body 8 around the rotation axis A1. At the same time, the second rotating body 9 is configured to rotate relative to the first rotating body 8 around the second rotation axis A2. Thereby, the output part 11 and the arm member 4b on the tool side engaged with the output unit 11 can perform a rotational movement around the joint axis A5 with respect to the arm member 4a on the base side.

  The first rotation axis A1, the second rotation axis A2, the extension axis A3, and the joint axis A5 intersect at one point, and this intersection point forms the center of the rotation mechanism 7. Regardless of the rotation angle of the first and second rotating bodies 8 and 9, the center position of the rotating mechanism 7 does not change with respect to the arm members 4a and 4b. In the present embodiment, the first rotation axis A1 is orthogonal to the joint axis A5. The second rotation axis A2 is inclined 135 degrees with respect to the first rotation axis A1. The extending axis A3 is inclined 45 degrees with respect to the second rotation axis A2.

  FIG. 3 is an operation explanatory diagram of the joint structure according to the embodiment. In the following description, an XYZ coordinate system in which the origin is placed on the arm member 4a is assumed. For convenience of illustrating the operations of the first and second rotating bodies 8 and 9, notches 8 n and 9 n are provided on the side surfaces of the first and second rotating bodies 8 and 9.

  In FIG. 3A, the joint axis A5 is oriented in the Y direction, and the first rotation axis A1 is oriented in the Z direction perpendicular to the Y direction. The directions of the joint axis A5 and the first rotation axis A1 do not change regardless of the rotation angles of the first and second rotating bodies 8 and 9. The second rotation axis A2 is inclined so as to extend from the intersection to the upper side in the Z direction and one side in the X direction, and is not directed in the Y direction. The extending axis A3 extends from the intersection to one side in the X direction that is orthogonal to both the Y direction and the Z direction.

  In order to rotationally move the tool side arm member 4b around the joint axis A5 with respect to the base side arm member 4a, the first rotating body 8 is moved from the state shown in FIG. Rotate clockwise.

  FIG. 3B shows a state after the first and second rotating bodies 8 and 9 have rotated the first rotation axis A1 by 90 degrees clockwise from the state shown in FIG. Due to this rotation, the second rotation axis A2 rotates 90 degrees clockwise with respect to the first rotation axis A1, and extends from the intersection to the upper side in the Z direction and one side in the Y direction. If it is assumed that the second rotating body 9 is not rotatable with respect to the first rotating body 8, the extending axis A3 rotates 90 degrees horizontally around the first rotating axis A1 from the state shown in FIG. Will be. The notch 9n of the second rotating body 9 is located on the upper right side (the other side in the Y direction and the upper side in the Z direction) similarly to the notch 8n of the first rotating body 8, and the output unit 11 is the center of the rotating mechanism 7. Extends to one side in the Y direction.

  However, in reality, the output unit 11 extends upward in the Z direction from the center of the rotation mechanism 7 in the state shown in FIG. 3B, and from the state shown in FIG. 3A to the state shown in FIG. The arm member 4a on the base side has been rotated 90 degrees counterclockwise about the joint axis A5. The arm member 4b on the tool side that engages with the output unit 11 also performs the same rotational movement. In order to realize the rotational movement of the output unit 11 and the arm member 4b, the second rotating body 9 rotates 90 degrees around the first rotation axis A1 with respect to the arm member 4a from the state shown in FIG. However, it rotates 180 degrees around the second rotation axis A2 with respect to the first rotating body 8 (the notch 9n of the second rotating body 9 is located on the lower left side (one side in the Y direction and the lower side in the Z direction). Point).

  FIG. 3C shows a state after the first and second rotating bodies 8 and 9 have rotated the first rotation axis A1 by 90 degrees clockwise from the state shown in FIG. 3B. By this rotation, the second rotation axis A2 rotates 90 degrees clockwise with respect to the first rotation axis A1, and extends from the intersection to the upper side in the Z direction and the other side in the X direction. In the state shown in FIG. 3B, since the extending axis A3 is coaxial with the first rotation axis A1, if the second rotating body 9 cannot rotate with respect to the first rotating body 8, the output unit 11 is The notch 9n of the second rotating body 9 is maintained in a state of extending upward in the Z direction, and is located on the lower left side (the other side in the X direction and the lower side in the Z direction).

  However, actually, the output unit 11 extends from the center of the rotation mechanism 7 to the other side in the X direction in the state shown in FIG. 3C, and the state shown in FIG. 3B is shown in FIG. Before reaching the state, it is rotated 90 degrees counterclockwise about the joint axis A5 with respect to the arm member 4a on the base side. The arm member 4b on the tool side that engages with the output unit 11 also performs the same rotational movement. In order to realize the rotational movement of the output unit 11 and the arm member 4b, the second rotating body 9 rotates 90 degrees around the first rotation axis A1 with respect to the arm member 4a from the state shown in FIG. However, it rotates 180 degrees around the second rotation axis A2 with respect to the first rotating body 8 (the notch 9n of the second rotating body 9 is located on the upper right side (one side in the X direction and the upper side in the Z direction)). See).

  From the state shown in FIG. 3A to the state shown in FIG. 3C, the first rotating body 8 rotates the first rotation axis A1 180 degrees clockwise with respect to the arm member 4a. The second rotator 9 rotates together with the first rotator 8 180 degrees around the first rotation axis A1 with respect to the arm member 4a, and 360 degrees around the second rotation axis A2 with respect to the first rotator 8. Rotate. Thereby, the output part 11 and the arm member 4b engaged therewith can rotate and move 180 degrees around the joint axis A5 with respect to the arm member 4a. When the state shown in FIG. 3C is changed from the state shown in FIG. 3C to the state shown in FIG. 3A through the state shown in FIG.

  In the joint structure according to the embodiment, the rotation around the joint axis A5 with respect to the arm member 4a on the base side of the arm member 4b on the tool side is realized as in the comparative example. The first rotating body 8 and the second rotating body 9 constitute a mechanical speed reducer. That is, the second rotating body 8 includes an output portion 11 extending along the extending axis A3. The output portion 11 engages with the arm member 4b on the tool side and rotates around the joint axis A5 together with the arm member 4b. Moving. The second rotation axis A2 is inclined with respect to the first rotation axis A1, the extending axis A3, and the joint axis A5, and the apparent length of the arm member 4b on the tool side viewed from the second rotating body 9 according to the inclination. (Turning radius) becomes shorter. For this reason, even when the weight of the tool, the actual length of the arm member 4b on the tool side, the weight, and the inertia ratio are the same as those of the conventional joint structure, the tool-side arm member 4b is compared with the conventional joint structure. The torque for maintaining the posture and the torque around the second rotation axis A2 of the second rotating body 9 necessary for accelerating the arm member 4b on the tool side are reduced. Accordingly, the first and second rotating bodies 8 and 9 and the components (for example, bearings) provided around the first and second rotating bodies 8 and 9 can be made smaller or have a longer life than a reduction gear in a conventional joint structure.

  The rotational speed of the output unit 11 around the joint axis A5 is smaller than the rotational speed of the second rotating body 9 around the second rotational axis A2. When the rotational speed of the rotary drive source 6 is increased to increase the rotational speed of the second rotating body 9, the arm member 4b rotates around the joint axis A5 at the same speed as before. The influence of the rotation speed on the life of the rotation mechanism 7 is smaller than that of the torque. For this reason, even if the rotational speed of the second rotating body 9 is made higher than that of the output element of the reduction gear 97 of the comparative example, and the arm member 4b is rotated at the same speed as that of the comparative example, the advantage of torque reduction is great. Thus, the rotation mechanism 7 can be reduced in size and extended in life.

  In the present embodiment, the inclination angle of the second rotation axis A2 with respect to the first rotation axis A1 is 135 degrees. The greater the inclination angle, the greater the torque-up effect in the rotating mechanism 7 (the effect of reducing the torque required for posture maintenance and acceleration), but the corresponding decrease in the rotational speed of the arm member 4b increases and the arm member increases. The movable range of 4b becomes narrow. If the inclination angle is small, the movable range of the arm member 4b can be widened, but the effect of increasing torque is reduced. In this embodiment, since the degree of inclination is set in the middle, securing the movable range and obtaining the torque increase effect are compatible.

  As shown in FIGS. 3A to 3C, if the inclination angle is 135 degrees, the movable range of the arm member 4b can be 180 degrees. Many joints of the robot arm have a sufficient movable range of 180 degrees, and it is beneficial to apply the joint structure according to the present embodiment to such a joint. It is only a preferable example that the inclination angle is set to 135 degrees, and the inclination angle can be appropriately changed according to the movable range required for the joint to be applied and the design specifications of the rotation mechanism and the rotation drive source. .

  Embodiment is an example and can be changed suitably in the range which does not deviate from the meaning of the present invention. For example, in FIGS. 2A and 3A to 3C, the first and second rotating bodies 8 and 9 are illustrated in a disk shape, but this is merely an example, and the axes A1 to A3 are If the first and second rotating bodies 8 and 9 are arranged as described above and rotate at a rotational speed necessary to rotate the output unit 11 and the arm member 4b around the joint axis A5, The first and second rotating bodies 8 and 9 may have any shape.

  The present invention can be applied to a joint of a robot arm.

A1 First rotation axis A2 Second rotation axis A3 Extension axis A5 Joint axis 1 Robot 2 Base 3 Robot arm 4 (4a to 4c) Arm member 5 (5a to 5c) Joint 6 Rotation drive source 7 Rotation mechanism 8 First Rotating body 9 Second rotating body 11 Output unit 50 Tool

Claims (1)

A joint structure of a robot that connects a tool side arm member to a base side arm member so as to be rotatable around a joint axis,
A first rotating body that rotates about a first rotation axis that intersects the joint axis with respect to the arm member on the base side;
A second rotating body that rotates around the second rotating axis that intersects with the first rotating axis and is inclined to the first rotating axis while rotating together with the first rotating body. ,
The second rotating body extends along an extending axis inclined from the intersection of the first rotating axis and the second rotating axis to the second rotating axis and engages with the arm member on the tool side. Including
The second rotating body rotates around the second rotation axis with respect to the first rotating body while rotating around the first rotation axis with respect to the arm member on the base side, so that the output unit and The joint structure of the robot, wherein the tool-side arm member that supports this rotates and moves around the joint axis with respect to the base-side arm member.

Images