Robot

Abstract

To provide a robot which enables reduction of influence of noise on a sensor with a simple structure.SOLUTION: A robot includes: a base 4; a first arm A1 which rotates relative to the base 4 through a first rotary shaft 6; a sensor 7 provided at the first rotary shaft 6; a bearing 11 provided at a position separated from the first rotary shaft 6 and the sensor 7 in the base 4; and projections 12 each of which is provided at a position, which faces the bearing 11, of the first arm A1 and contacts with the bearing 11 to cause the base 4 and the first arm A1 to ground.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a robot. [Background technology]

[0002] Articulated robots are used as industrial robots. These robots are equipped with multiple sensors, so there is a demand for improved noise resistance.

[0003] For example, Patent Document 1 discloses that noise generated by a motor, an electromagnetic brake, etc. is removed from the torque signal of a torque sensor by using a full-wave rectifier circuit, a differential amplifier, and a filter circuit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-323930 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, for example, a torque sensor may be provided on a shaft connecting the base and arm of the robot. When a sensor is provided inside the robot, the sensor is susceptible to noise from the motor, etc. For example, noise generated in a motor, etc. at the tip of the robot may escape to the arm, and the noise that escapes to the arm may be grounded to the ground on the base side via the shaft or torque sensor, in which case the torque sensor is susceptible to the noise. In this way, for example, a shaft may become a noise path between the members that make up the robot, so it is necessary to reduce the influence of noise on the sensor provided on the shaft.

[0006] However, the method for reducing noise disclosed in Patent Document 1 may have a complex configuration because it uses a filter circuit or the like.

[0007] In view of the above problems, an object of the present invention is to provide a robot that can reduce the effect of noise on sensors with a simple structure. [Means for solving the problem]

[0008] In order to solve the above problems, the robot of the present invention comprises a first member, a second member that rotates relative to the first member via an axis, a sensor provided on the axis, a first conductive part provided on the first member at a position spaced apart from the axis and the sensor, and a second conductive part provided on the second member at a position facing the first conductive part and contacting the first conductive part to ground the first member and the second member.

[0009] In the robot, the first member is a base and the second member is an arm.

[0010] In addition, in the robot, one of the first conductive part and the second conductive part is a thrust bearing with the axis as a rotation axis, and the other of the first conductive part and the second conductive part is a protrusion that contacts at least a portion of the thrust bearing. Effect of the Invention

[0011] According to the robot of the present invention, the influence of noise on the sensor can be reduced with a simple structure. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating an example of an overall configuration of a robot according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view showing an example of the configuration of a connection portion between a base and a first arm in the robot of FIG. 1. [Diagram 3] FIG. 3 is a diagram showing an example of the bearing of FIG. 2. [Figure 4]4 is a cross-sectional view taken along line IV-IV in FIG. 2 at a connection portion between the base and the first arm in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same reference numerals are used to designate the same components in each drawing, and duplicated description will be omitted as appropriate.

[0014] === Implementation form === <Overall composition> 1 is a diagram illustrating an example of the overall configuration of a robot 1 according to an embodiment of the present invention (hereinafter, referred to as "the present embodiment"). The robot 1 is an industrial robot that performs processes such as machining and transporting a workpiece.

[0015] The robot 1 is an articulated robot and has multiple arms and multiple joints. In the robot 1, a first member and a second member move relatively at the joints. In the robot 1, the first member and the second member, which are connected to each other at the joints, rotate relatively via an axis, and the robot 1 as a whole performs an operation.

[0016] Specifically, the robot 1 includes a base 4, a first arm A1, a second arm A2, a third arm A3, and a fourth arm A4 as a first member or a second member. The base 4, the first arm A1, the second arm A2, the third arm A3, and the fourth arm A4 have housings (exteriors) made of, for example, a conductive member.

[0017] The base 4 is a foundation for the robot 1, and is provided on an installation surface on which the robot 1 is placed. In other words, the base 4 is fixed to the floor surface and supports the robot 1 in its entirety.

[0018] The first arm A1 is connected to the base 4 at a first joint J1 via a first rotation shaft (rotation shaft) 6. The first arm A1 is rotatable relative to the base 4 via the first rotation shaft 6. A first motor 8 (described later) is provided inside the base 4 and rotates the first rotation shaft 6. The first motor 8 and the first rotation shaft 6 are connected via a reducer or the like. When the first motor 8 rotates the first rotation shaft 6, the first arm A1 rotates around the first rotation shaft 6 relative to the base 4. The first motor 8 may generate noise, but the generated noise is dissipated to, for example, the housing of the base 4.

[0019] The second arm A2 is connected to the first arm A1 via a second rotation shaft at the second joint J2, and is rotatable about the second rotation shaft relative to the first arm A1 by a second motor connected to the second rotation shaft. The second motor may generate noise, but the generated noise is dissipated, for example, to the housing of the first arm A1.

[0020] The third arm A3 is connected to the second arm A2 via a third rotation shaft at the third joint J3, and is rotatable about the third rotation shaft relative to the second arm A2 by a third motor connected to the third rotation shaft. The third motor may generate noise, but the generated noise is dissipated to, for example, the housing of the second arm A2.

[0021] The fourth arm A4 is connected to the third arm A3 via a fourth rotation shaft at a fourth joint J4, and is rotatable about the fourth rotation shaft relative to the third arm A3 by a fourth motor connected to the fourth rotation shaft. The fourth motor may generate noise, but the generated noise is dissipated to, for example, the housing of the third arm A3.

[0022] <Detailed configuration> Fig. 2 is a diagram showing an example of a first joint J1 between the base 4 and the first arm A1. As shown in Fig. 2, the robot 1 includes the first motor 8 and the first rotating shaft 6 driven by the first motor 8 as described above, and the base 4 and the first arm A1 are connected via the first rotating shaft 6.

[0023] Further, a sensor 7 is provided on the first rotating shaft 6. The sensor 7 is, for example, a torque sensor. The sensor 7 detects the torque applied to the first rotating shaft 6. For example, the sensor 7 detects torsion by attaching a strain gauge to the first rotating shaft 6.

[0024] The robot 1 also includes a grounding arrangement 10 at the first joint J1 as a connection portion. The grounding arrangement 10 is configured to ground the base 4 and the first arm A1. Grounding refers to a connection state in which the base 4 and the first arm A1 are at the same reference potential. The reference potential point is, for example, 0V.

[0025] The grounding structure 10 is mainly composed of a bearing 11 as a first conductive part and a protrusion 12 as a second conductive part.

[0026] The bearing 11 is a conductive portion provided on the base 4. Specifically, the bearing 11 is a thrust bearing. A thrust bearing is a bearing that can support a load applied in the axial direction of a rotating shaft (rotating shaft).

[0027] FIG. 3 is a diagram showing an example of the bearing 11. As shown in FIG. 3, in this embodiment, the bearing 11 will be described as a thrust roller bearing. The bearing 11 has a rotation axis serving as a central axis and a plurality of rollers 15 serving as rotating members arranged in the circumferential direction. The rotation axis of the bearing 11 is the same as the first rotation axis 6. In other words, the center of rotation of the bearing 11 and the center of rotation by the first rotation axis 6 are the same. Therefore, the rotation by the bearing 11 does not hinder the rotation of the base 4 and the first arm A1 on the first rotation axis 6.

[0028] The bearing 11 is provided at a position on the base 4 away from the first rotation shaft 6 and the sensor 7. Specifically, the bearing 11 is provided around the first rotation shaft 6 and the sensor 7 on the base 4 and away from them. In other words, the bearing 11 does not contact the first rotation shaft 6 or the sensor 7. In particular, it is preferable that the bearing 11 is provided at a position as far away as possible from the first rotation shaft 6 and the sensor 7.

[0029] The bearing 11 is grounded to the earth, i.e., the bearing 11 is earth-connected.

[0030] The protrusion 12 is a conductive portion provided on the first arm A1. The protrusion 12 is a convex portion that protrudes from the first arm A1 towards the base 4. The protrusion 12 may be provided on the first arm A1 as, for example, a conductive member, or may be provided integrally with the conductive housing of the first arm A1. The protrusion 12 is connected to the housing of the first arm A1. That is, noise flowing in the first arm A1 can be conducted to the protrusion 12.

[0031] The protrusion 12 is provided at a position on the first arm A1 spaced apart from the first rotation shaft 6 and the sensor 7. Specifically, the protrusion 12 is provided around the first rotation shaft 6 and the sensor 7 on the first arm A1 and spaced apart from them. In other words, the protrusion 12 does not contact the first rotation shaft 6 or the sensor 7. In particular, it is preferable that the protrusion 12 is provided at a position as far away from the first rotation shaft 6 and the sensor 7 as possible.

[0032] The protrusion 12 then comes into contact with the bearing 11 on the base 4. Specifically, the protrusion 12 comes into contact with a part of the bearing 11, i.e., the roller 15. This allows the protrusion 12 and the bearing 11 to form a conductive path. As described above, since the bearing 11 is provided with a plurality of rollers 15 in the circumferential direction, it is preferable that the protrusion 12 has a length in the circumferential direction with respect to the rotation axis so as to come into contact with the plurality of rollers 15. In this way, even if the protrusion 12 moves in the rotation direction due to the rotation of the first arm A1, it can come into contact with at least one roller 15.

[0033] Moreover, a plurality of protrusions 12 are provided in the circumferential direction of the rotation shaft, and each of the protrusions 12 contacts the bearing 11. FIG. 4 is a cross-sectional view taken along line IV-IV at the first joint J1 between the base 4 and the first arm A1 in FIG. 2. As shown in FIG. 4, the bearing 11 is provided on the base 4, and the protrusions 12 are provided on the first arm A1 so as to contact the bearing 11. For example, three protrusions 12 are provided in the circumferential direction of the first rotation shaft 6. The centers of the respective protrusions 12 are shifted by 120 degrees in the circumferential direction of the first rotation shaft 6. In this way, by providing a plurality of protrusions 12 in the circumferential direction, the load of the first arm A1, etc. can be applied to the bearing 11 approximately evenly. Also, the load on the first rotation shaft 6 can be suppressed.

[0034] In this way, the base 4 as the first member and the first arm A1 as the second member are grounded by contacting the bearing 11 as the first conductive part and the protrusion 12 as the second conductive part at the first joint J1 between the base 4 and the first arm A1. In the robot 1, a noise generating configuration such as a second motor, a third motor, and an electromagnetic brake is provided on the tip side of the arm from the first joint J1 between the base 4 and the first arm A1. If these noise generating configurations are considered as noise sources, for example, the noise generated by the noise source is released to the housing of the arm in which the noise source is provided. For example, if the second motor is considered as the noise source, the noise generated by the second motor is released to the housing of the first arm A1. Then, in order to release the noise generated in this way from the base 4 of the robot 1 to the ground, the noise flows from the protrusion 12 to the bearing 11 at the first joint J1 between the base 4 and the first arm A1 and then to the ground.

[0035] <Action and effect> As described above, in the present embodiment, the robot 1 is configured to ground the base 4 and the first arm A1 by contacting the bearing 11 provided at a position on the base 4 away from the first rotation shaft 6 and the sensor 7 with the protrusion 12 provided at a position on the first arm A1 facing the bearing 11, so that the bearing 11 and the protrusion 12 form a path through which noise flows, thereby suppressing the effect of noise on the sensor 7 provided on the first rotation shaft 6. For example, a collaborative robot tends to be provided with a large number of sensors, but even in such a case, the noise resistance performance can be improved. In addition, since the path through which noise flows can be formed with a simple configuration, the configuration can be prevented from becoming complicated.

[0036] In addition, by using the first member as the base 4 and the second member as the first arm A1, and forming a path for noise to flow at the base 4 and the first joint J1 of the first arm A1 by the bearing 11 and the protrusion 12, the effect of noise on the sensor 7 provided on the first rotating shaft 6 can be suppressed at the first joint J1 of the base 4 and the first arm A1, where particularly large noise is likely to flow.

[0037] Furthermore, by using the bearing 11 and the protrusion 12 as the first conductive portion and the second conductive portion, a path through which noise flows can be formed and the first arm A1 can be supported relative to the base 4.

[0038] === Variations === The present invention is not limited to the above-described embodiment. In other words, the above-described specific example may be modified by a person skilled in the art as appropriate, and the modifications may be included in the scope of the present invention as long as they include the features of the present invention. In addition, the elements of the above-described embodiment and the following modifications may be combined to the extent technically possible, and the combinations of these may be included in the scope of the present invention as long as they include the features of the present invention.

[0039] For example, in the above embodiment, the case where the base 4 as the first member and the first arm A1 as the second member are connected by the first rotating shaft 6 as an axis has been described as an example, but the connection parts related to other joints may be configured in a similar manner. For example, the first arm A1 may be the first member, the second arm A2 may be the second member, and the second joint J2 may be configured in the same manner as the base 4 and the first arm A1, or the second arm A2 may be the first member, the third arm A3 may be the second member, and the connection parts may be configured in the same manner as the base 4 and the first arm A1. Note that, regardless of the configuration of the robot 1 in FIG. 1, the first member and the second member connected by an axis may be configured in the same manner as in FIG. 2.

[0040] In the above embodiment, the bearing 11 as the first conductive part is a thrust roller bearing, but the present invention is not limited to the thrust roller bearing. For example, a thrust bearing other than the roller 15 may be used, or a bearing other than a thrust bearing may be used.

[0041] In the above embodiment, the base 4 as the first member is provided with the bearing 11 as the first conductive part, and the first arm A1 as the second member is provided with the protrusion 12 as the second conductive part. However, the protrusion 12 may be provided on the first member, and the bearing 11 may be provided on the second member. In other words, one of the first conductive part and the second conductive part may be the bearing 11, and the other of the first conductive part and the second conductive part may be the protrusion 12.

[0042] In addition, in this embodiment, the case where three protrusions 12 are provided in the circumferential direction of the first rotating shaft 6 has been described, but the number and shape of the protrusions 12 are not limited. For example, the number of protrusions 12 may be one or more. When there is one protrusion 12, the protrusion 12 may be configured around the entire circumference, or may be configured around a portion of the circumference.

[0043] In addition, in this embodiment, the bearing 11 is used as the first conductive part, and the protrusion 12 is used as the second conductive part, but it is possible to use a conductive part other than the bearing 11 and the protrusion 12 as long as it can be grounded at a position separated from the first rotating shaft 6 and the sensor 7. For example, the conductive part may be formed using a gear. In other words, as long as the first member and the second member are rotatable and can be grounded at a position separated from the first rotating shaft 6 and the sensor 7, various shapes can be used as the conductive part. [Explanation of symbols]

[0044] 1:Robot 4: Base (first component) 6: First rotating shaft (axis) 7: Sensor 11: Bearing (first conductive part) 12: Protrusion (second conductive part) 15: Roller (rotating member) A1: First arm (second member)

Claims

1. A first member; A second member that rotates relative to the first member via a shaft; A sensor provided on the shaft; a first conductive portion provided in the first member at a position spaced apart from the shaft and the sensor; a second conductive portion provided at a position facing the first conductive portion on the second member and contacting the first conductive portion to ground the first member and the second member; A robot comprising:

2. the first member is a base, The robot according to claim 1 , wherein the second member is an arm.

3. one of the first conductive portion and the second conductive portion is a thrust bearing that rotates around the shaft, 3. The robot according to claim 1, wherein the other of the first conductive portion and the second conductive portion is a protrusion that contacts at least a portion of the thrust bearing.

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