Multi-joint robot

Abstract

To provide an art which enables improvement of location accuracy of a fingertip of a multi-joint robot.SOLUTION: A multi-joint robot of the disclosure includes: a base; a first arm connected to the base and configured to be rotationally driven relative to the base; and a first drive device which causes the first arm to rotate relative to the base. The first drive device has a first motor and a first speed reducer. A rotation axis of the first motor intersects with an output shaft of the first speed reducer.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a multi-joint robot.

Background Art

[0002] Patent Document 1 discloses a painting method using a working robot. In this method, a print head is attached to the hand part of the working robot, and printing is executed while moving the print head while maintaining a constant distance between the printing target and the print head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above prior art, the positional accuracy of the hand part of the working robot is important for improving the painting quality. Not limited to painting, when performing work using a multi-joint robot, positional accuracy is important. Therefore, a technique for improving the positional accuracy of the tip of a multi-joint robot is desired.

Means for Solving the Problems

[0005] According to one aspect of the present disclosure, a multi-joint robot is provided. This multi-joint robot includes a base, a first arm connected to the base and rotatably driven with respect to the base, and a first driving device that rotates the first arm with respect to the base. The first driving device has a first motor and a first speed reducer, and the rotation axis of the first motor and the output axis of the first speed reducer intersect.

Brief Description of the Drawings

[0006]

Figure 1

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Embodiments for Carrying Out the Invention

[0007] A. First Embodiment: FIG. 1 is an explanatory diagram showing the configuration of the scalar robot 101 in the first embodiment, and FIG. 2 is its configuration diagram. The scalar robot 101 includes a base 110, a first arm 121, a second arm 122, and a shaft 130. The shaft 130 is provided at the tip portion of the second arm 122.

[0008] The first arm 121 is connected to the base 110 at the first joint J1 and is configured to be rotatable with respect to the base 110. The second arm 122 is connected to the first arm 121 at the second joint J2 and is configured to be rotatable with respect to the first arm 121. The shaft 130 is connected to the tip portion of the second arm 122 at the third joint J3 and is configured to be vertically movable with respect to the second arm 122. The shaft 130 is further rotatably supported at the fourth joint J4. On the outer periphery of the shaft 130, a helical ball screw groove 133 and a spline groove 134 parallel to the central axis of the shaft 130 are provided. The ball screw groove 133 is used to raise and lower the shaft 130 at the third joint J3. The spline groove 134 is used to rotate the shaft 130 at the fourth joint J4. An end effector is attached to the lower end of the shaft 130. The end effector is not shown in the figure. An electrical wiring 140 is provided between the base 110 and the second arm 122.

[0009] The joints J1, J2, and J4 are rotary joints that rotate horizontally, and the joint J3 is a linear motion joint that moves vertically. However, the third joint J3 may be a rotary joint and the fourth joint J4 may be a linear motion joint. The scalar robot 101 of the first embodiment is a horizontal multi-joint robot. Note that the number of joints can be set to any integer of 2 or more.

[0010] FIG. 3 is an explanatory diagram showing the drive devices of the respective axes of the scalar robot 101 in the first embodiment. The base 110 is provided with a first drive device 151 that drives the first joint J1. The first drive device 151 is configured to rotate the first arm 121 with respect to the base 110. The first drive device 151 includes a first motor M1 and a first speed reducer G1 connected to the first motor M1. The first speed reducer G1 is configured such that the input shaft A1m and the output shaft A1g intersect. The input shaft A1m corresponds to the rotation shaft of the first motor M1. The output shaft A1g corresponds to the rotation shaft of the first joint J1. The output shaft A1g is fixed to the housing of the first arm 121.

[0011] As the first speed reducer G1, various speed reducers in which the input shaft A1m and the output shaft A1g intersect can be used. For example, a roller gear cam speed reducer, a worm gear speed reducer, a bevel gear speed reducer, etc. may be used as the first speed reducer G1. In the first embodiment, it is preferable that the first speed reducer G1 uses a rolling contact transmission mechanism such as a roller gear cam speed reducer. Since the rolling contact transmission mechanism has less backlash than a general harmonic gear speed reducer, the positional accuracy of the joint can be improved.

[0012] If a speed reducer in which the input shaft A1m and the output shaft A1g intersect is used as the first speed reducer G1, the height of the base 110 can be made smaller compared to the case of using a general harmonic gear speed reducer, and the positional accuracy of the hand can be improved. The height of the base 110 when a speed reducer in which the input shaft A1m and the output shaft A1g intersect is used will be described later in more detail.

[0013] Inside the first arm 121, a second drive device 152 for driving the second joint J2 is provided. The second drive device 152 is configured to rotate the second arm 122 with respect to the first arm 121. The second drive device 152 includes a second motor M2 and a second speed reducer G2 connected to the second motor M2. The second speed reducer G2 preferably has the same configuration as the first speed reducer G1. That is, the second speed reducer G2 is preferably configured such that the input shaft A2m and the output shaft A2g intersect. The input shaft A2m corresponds to the rotation shaft of the second motor M2. The output shaft A2g corresponds to the rotation shaft of the second joint J2. The output shaft A2g is fixed to the housing of the second arm 122.

[0014] In the first embodiment, since the second drive device 152 is provided on the first arm 121, the center of gravity of the robot is lower than when the second drive device 152 is provided on the second arm 122. If the center of gravity of the robot is lowered, there is an advantage that the sway of the robot is reduced and the positional accuracy can be further improved.

[0015] As the second speed reducer G2, it is also possible to use a speed reducer in which the input shaft A2m and the output shaft A2g are parallel. As the speed reducer in which the input shaft A2m and the output shaft A2g are parallel, it is possible to use a harmonic gear speed reducer, a traction drive unit, a spur gear speed reducer, or the like. The harmonic gear speed reducer and the traction drive unit are preferable in that they have little backlash. Further, the harmonic gear speed reducer is preferable in that it is lightweight and can improve energy saving performance.

[0016] Inside the second arm 122, a third drive device 153 that drives the third joint J3 and a fourth drive device 154 that drives the fourth joint J4 are provided.

[0017] The third drive device 153 is configured to move the shaft 130 up and down with respect to the second arm 122, that is, to raise and lower it. The third drive device 153 includes a third motor M3, a third speed reducer G3 connected to the third motor M3, and a rotation transmission mechanism T3 connected to the third speed reducer G3. The third speed reducer G3 preferably has the same configuration as the first speed reducer G1. That is, the third speed reducer G3 is preferably configured such that the input shaft A3m and the output shaft A3g intersect. The input shaft A3m corresponds to the rotation shaft of the third motor M3. The output shaft A3g is parallel to the central axis of the shaft 130. The rotation transmission mechanism T3 has, for example, a pulley fixed to the output shaft A3g of the third speed reducer G3, a ball screw nut engaged with the ball screw groove 133 of the shaft 130, and a transmission belt connecting the pulley and the ball screw nut. When the third motor M3 rotates, the ball screw nut rotates around the central axis of the shaft 130, and the shaft 130 moves up and down in response to this rotation.

[0018] As the third speed reducer G3, it is also possible to use a speed reducer in which the input shaft A3m and the output shaft A3g are parallel. As the speed reducer in which the input shaft A3m and the output shaft A3g are parallel, it is possible to use a harmonic gear speed reducer, a traction drive unit, a spur gear speed reducer, or the like.

[0019] The fourth drive device 154 is configured to rotate the shaft 130. The fourth drive device 154 includes a fourth motor M4, a fourth speed reducer G4 connected to the fourth motor M4, and a rotation transmission mechanism T4 connected to the fourth speed reducer G4. The fourth speed reducer G4 preferably has the same configuration as the first speed reducer G1. That is, the fourth speed reducer G4 is preferably configured such that the input shaft A4m and the output shaft A4g intersect. The input shaft A4m corresponds to the rotation shaft of the fourth motor M4. The output shaft A4g is parallel to the central axis of the shaft 130. The rotation transmission mechanism T4 includes, for example, a pulley fixed to the output shaft A4g of the fourth speed reducer G4, a spline nut engaged with the spline groove 134 of the shaft 130, and a transmission belt connecting the pulley and the spline nut. When the fourth motor M4 rotates, the spline nut rotates around the central axis of the shaft 130, and the shaft 130 rotates accordingly.

[0020] As the fourth speed reducer G4, it is also possible to use a speed reducer in which the input shaft A4m and the output shaft A4g are parallel. As the speed reducer in which the input shaft A4m and the output shaft A4g are parallel, it is possible to use a harmonic gear speed reducer, a traction drive unit, a spur gear speed reducer, or the like.

[0021] Note that since the third drive device 153 and the fourth drive device 154 are provided in the second arm 122, it is preferable in that the overall height of the robot can be reduced by reducing the heights of the third drive device 153 and the fourth drive device 154. For this purpose, it is preferable to arrange the third motor M3 and the fourth motor M4 in a lying state. When the output shaft A3g of the third speed reducer G3 is parallel to the vertical direction as in the example of FIG. 3, if a speed reducer in which the input shaft A3m and the output shaft A3g intersect is used, the input shaft A3m becomes horizontal. In this case, since the output shaft of the third motor M3 is parallel to the horizontal direction, the third motor M3 can be arranged in a lying state. If the third motor M3 is installed in a lying state when the third motor M3 has a shape in which the total length along its output shaft is larger than the total width, the overall height of the robot can be reduced. The same applies to the fourth motor M4.

[0022] FIG. 4 is an explanatory diagram showing a comparison of the height of the base 110 due to the difference in the first speed reducer G1. In FIG. 4, the shapes of the respective parts are drawn in a size close to the actual size. As described with reference to FIG. 3, the first speed reducer G1 of the scalar robot 101 of the first embodiment is configured such that the input shaft A1m and the output shaft A1g intersect. On the other hand, the first speed reducer G1c of the scalar robot 101c of the comparative example is configured such that the input shaft A1m and the output shaft A1g are parallel. A typical motor generally has a shape in which the total length along its output shaft is larger than the total width.

[0023] In the scalar robot 101 of the first embodiment, since the first motor M1 can be horizontally placed inside the base 110, the height H1 of the base 110 can be reduced. On the other hand, in the scalar robot 101c of the comparative example, since the first motor M1 is vertically placed inside the base 110c, the height H1c of the base 110c becomes larger than the height H1 of the base 110 of the first embodiment. As a result, the overall height of the scalar robot 101c of the comparative example becomes larger than that of the scalar robot 101 of the first embodiment. Assuming that the same vibration is received from the installation surface FL, in the scalar robot 101c of the comparative example with a larger overall height, the vibration of the portion located at a higher position becomes larger, resulting in a larger vibration at the tip and a decrease in the position accuracy of the tip. Conversely, in the scalar robot 101 of the first embodiment, since the overall height can be reduced, the vibration of the portion located at a higher position is smaller than that of the comparative example. Therefore, the position accuracy of the tip can be improved. Note that "horizontally placed" means an arrangement in which the longitudinal direction of the motor is oriented in the horizontal direction. "Vertically placed" means an arrangement in which the longitudinal direction of the motor is oriented in the vertical direction. Also, as an example of the "portion located at a higher position", the second arm 122 can be cited.

[0024] In the scalar robot 101 of the first embodiment, since the height H1 of the base 110 is lower than that of the comparative example, the length L3 of the shaft 130 is also smaller than the length L3c of the shaft 130c of the comparative example. In the scalar robot 101 of the first embodiment, since the shaft 130 is short, the deformation of the shaft 130 is small, and the position accuracy of the tip is further improved.

[0025] Thus, if a speed reducer in which the input shaft A1m and the output shaft A1g intersect is used as the first speed reducer G1, the height of the base 110 can be reduced, and the position accuracy of the tip can be improved. Further, in the scalar robot of the first embodiment, since the height of the base 110 is small, the shaft 130 can be shortened, the deformation of the shaft 130 is reduced, and the position accuracy of the tip can be further improved.

[0026] FIG. 5 is an explanatory diagram showing the configuration of a roller gear cam speed reducer 10 which is an example of a rolling contact transmission mechanism. The roller gear cam speed reducer 10 has a substantially rod-shaped roller gear cam 11 and a substantially ring-shaped turret 12. A gear cam which is a spiral protrusion is formed around the roller gear cam 11. A cam follower that engages with the roller gear cam 11 is formed on the outer peripheral portion of the turret 12. A hollow portion 13 is formed at the center of the turret 12. The axis of the roller gear cam 11 corresponds to the input shaft Am of the roller gear cam speed reducer 10. The center line of the turret 12 corresponds to the output shaft Ag of the roller gear cam speed reducer 10. The input shaft Am and the output shaft Ag intersect each other. Further, the input shaft Am and the output shaft Ag are arranged such that the input shaft Am and the output shaft Ag are orthogonal to each other when observed from the direction D1 perpendicular to both the input shaft Am and the output shaft Ag.

[0027] Mathematically speaking precisely, the input shaft Am and the output shaft Ag of the roller gear cam speed reducer 10 are in a "twisted position". In the present disclosure, the term "intersect" for two shafts is used in a meaning that also includes the relationship that they are in a "twisted position".

[0028] The roller gear cam reducer 10 is a type of rolling contact transmission mechanism that transmits power by frictional force through rolling contact of multiple members. Since the roller gear cam reducer 10 has almost no backlash, it can achieve higher position accuracy and trajectory accuracy compared to ordinary harmonic gear reducers and bevel gear reducers.

[0029] In the scalar robot 101 of the first embodiment, it is preferable to configure one or more of the four reducers G1 to G4 using the roller gear cam reducer 10. By doing so, the position accuracy and trajectory accuracy of the end effector can be improved. Also, the more the number of reducers using the roller gear cam reducer 10, the higher the position accuracy and trajectory accuracy of the end effector can be. However, the roller gear cam reducer 10 tends to be larger in size compared to the harmonic gear reducer. Considering this point, it is preferable not to use the roller gear cam reducer 10 near the end effector of the robot, and it is preferable to use it at a position closer to the base 110.

[0030] FIG. 6 is an explanatory diagram showing the configuration of a traction drive unit 20, which is another example of a rolling contact transmission mechanism. The traction drive unit 20 has a ring-shaped fixed wheel 21, a plurality of planetary rollers 22 housed inside the fixed wheel 21, and a sun shaft 23 installed at the center of the plurality of planetary rollers 22. The plurality of planetary rollers 22 are connected to a planetary carrier (not shown). The traction drive unit 20 is a type of rolling contact transmission mechanism that transmits power by frictional force through rolling contact of the sun shaft 23 and the plurality of planetary rollers 22. The sun shaft 23 corresponds to the input shaft Am of the traction drive unit 20. The central axis of the planetary carrier corresponds to the output shaft Ag of the traction drive unit 20. The input shaft Am and the output shaft Ag of the traction drive unit 20 are parallel to each other. More specifically, the input shaft Am and the output shaft Ag of the traction drive unit 20 are on the same straight line.

[0031] The traction drive unit 20 is also a type of rolling contact transmission mechanism that transmits power by frictional force through rolling contact of a plurality of members. Since the traction drive unit 20 has no backlash, it can achieve higher position accuracy and trajectory accuracy compared to ordinary harmonic gear reducers and bevel gear reducers. However, the traction drive unit 20 tends to have a smaller output torque compared to harmonic gear reducers. Considering this point, the traction drive unit 20 is preferably used near the tip of the robot's hand.

[0032] As described above, since the scalar robot 101 of the first embodiment uses the first drive device 151 in which the rotation axis of the first motor M1 and the output axis of the first speed reducer G1 intersect, the height of the base 110 is reduced, and high position accuracy can be ensured even when holding a workpiece. Also, since the shaft 130 becomes shorter, deformation of the shaft 130 can be suppressed to a small level, and the position accuracy of the robot can be further improved.

[0033] The scalar robot 101 of the first embodiment can be used for various operations as follows. These operations may also be executed using robots of other embodiments described later. (1) A conveying operation of conveying a secondary battery as a workpiece. In this conveying operation, for example, by stacking secondary batteries, a stacked body composed of a plurality of stacked secondary batteries can be formed. Since the height of the base 110 of the scalar robot 101 is small, even in an operation with a large transportable weight such as the conveying operation of secondary batteries, the workpiece is less likely to shake, and the position accuracy of the workpiece can be improved. (2) An operation of discharging a liquid using a head that discharges the liquid and is attached to the lower end of the shaft 130. Since the scalar robot 101 has high position accuracy at the tip, high-precision liquid discharge can be achieved. (3) A welding operation or a measuring operation. Since the scalar robot 101 has high position accuracy at the tip, high-precision welding and measurement can be achieved. (4) A cutting operation or a polishing operation. Since the scalar robot 101 has high positional accuracy at the tip and high rigidity, accurate cutting and polishing can be achieved.

[0034] As described above, in the first embodiment, since the first drive device 151 is configured using the first speed reducer G1 in which the input shaft and the output shaft intersect, high positional accuracy can be ensured when performing an operation of holding a workpiece.

[0035] Also, in the first embodiment, since the second drive device 152 is configured using the second speed reducer G2 in which the input shaft and the output shaft intersect, the positional accuracy can be further improved. Furthermore, in the first embodiment, since the third drive device 153 is configured using the third speed reducer G3 in which the input shaft and the output shaft intersect, the third motor M3 can be placed lying down, and the overall height of the robot can be reduced.

[0036] B. Second Embodiment: FIG. 7 is an explanatory diagram showing the drive devices of each axis of the scalar robot 102 in the second embodiment. The difference between the second embodiment and the first embodiment is only that the second drive device 152 is provided on the second arm 122, and the other configurations are the same as those in the first embodiment.

[0037] In the second embodiment, since the second speed reducer G2 is a roller gear cam speed reducer and is provided on the second arm 122, the first arm 121 can be hollowed out, and a structure that facilitates passing of electrical wiring can be achieved. Also, if the electrical wiring is housed inside the first arm 121, there is no need to install the electrical wiring outside the housing of the robot, so the entire robot can be downsized.

[0038] FIG. 8 is an explanatory diagram showing the path of the electrical wiring in the second embodiment. Inside the second arm 122, electrical wiring 160 connected to the motors M2, M3, and M4 is provided. This electrical wiring 160 also includes wiring for an encoder (not shown). The electrical wiring 160 is preferably installed to follow the following path. (i) The electrical wiring 160 passes through the hollow portion 13 of the turret 12 of the roller gear cam reducer 10 that constitutes the second speed reducer G2, and enters from the second arm 122 into the first arm 121. (ii) Next, the electrical wiring 160 passes through the hollow portion inside the first arm 121 and reaches above the base 110. (iii) Further, the electrical wiring 160 passes through the hollow portion 13 of the turret 12 of the roller gear cam reducer 10 that constitutes the first speed reducer G1, and reaches inside the base 110. Note that the central axes of the first joint J1 and the second joint J2 preferably have a hollow structure.

[0039] If the electrical wiring 160 is arranged in this way, the electrical wiring 160 can be arranged to pass through the inside of the first arm 121, so that the number of wirings arranged outside the robot arm can be reduced. It is also possible to eliminate the wirings arranged outside the robot arm.

[0040] C. Third Embodiment: FIG. 9 is an explanatory diagram showing the drive devices of the respective axes of the scalar robot 103 in the third embodiment. The difference between the third embodiment and the first embodiment is only the configuration of the second drive device 152a, and the other configurations are the same as those of the first embodiment.

[0041] The second drive device 152a of the third embodiment includes a second motor M2 and a second speed reducer G2a connected to the second motor M2. The second speed reducer G2a is configured such that the input shaft A2m and the output shaft A2g are parallel. The input shaft A2m and the output shaft A2g are preferably on the same straight line. The input shaft A2m corresponds to the rotation shaft of the second motor M2. The second speed reducer G2 is preferably composed of a rolling contact transmission mechanism such as a traction drive unit 20 or a harmonic gear device.

[0042] By using the second speed reducer G2a in which the input shaft A2m and the output shaft A2g are parallel, the weight of the robot's end effector can be reduced. As a result, the energy saving performance can be improved.

[0043] D. Fourth Embodiment: FIG. 10 is an explanatory diagram showing the configuration of a six-axis robot 201 according to the fourth embodiment. This six-axis robot 201 includes a base 210, first to fifth arms 221 to 225, and an arm end 226. An end effector can be connected to the arm end 226. The first arm 221 is connected to the base 210 at a first joint J1, and the second to fifth arms 222 to 225 are sequentially connected at second to fifth joints J2 to J5. Further, the arm end 226 is connected to the fifth arm 225 at a sixth joint J6. All six joints J1 to J6 are rotational joints. More specifically, joints J2, J3, and J5 are bending joints, and the other joints J1, J4, and J6 are torsion joints. The six-axis robot 201 of the fourth embodiment is a vertically articulated robot. Note that the number of joints can be set to any integer of 2 or more.

[0044] In FIG. 10, among the six joints J1 to J6, only the drive devices of the first joint J1, the second joint J2, and the third joint J3 are illustrated. Inside the base 210, a first drive device 251 for driving the first joint J1 is provided. The first drive device 251 is configured to rotate the first arm 221 with respect to the base 210. The first drive device 251 includes a first motor M1 and a first speed reducer G1 connected to the first motor M1. The first speed reducer G1 is preferably configured such that an input shaft A1m and an output shaft A1g intersect. The input shaft A1m of the first speed reducer G1 corresponds to the rotation shaft of the first motor M1. The output shaft A1g of the first speed reducer G1 corresponds to the rotation shaft of the first joint J1. In the fourth embodiment, the first speed reducer G1 is preferably composed of a rolling contact transmission mechanism such as a roller gear cam reducer 10.

[0045] Inside the first arm 221, a second drive device 252 for driving the second joint J2 is provided. The second drive device 252 is configured to rotate the second arm 222 with respect to the first arm 221. The second drive device 252 includes a second motor M2 and a second speed reducer G2 connected to the second motor M2. The second speed reducer G2 preferably has the same configuration as the first speed reducer G1. That is, the second speed reducer G2 is preferably configured such that the input shaft A2m and the output shaft A2g intersect. The input shaft A2m corresponds to the rotation shaft of the second motor M2. The second speed reducer G2 is preferably composed of a rolling contact transmission mechanism such as the roller gear cam reducer 10.

[0046] Inside the second arm 222, a third drive device 253 for driving the third joint J3 is provided. The third drive device 253 is configured to rotate the third arm 223 with respect to the second arm 222. The third drive device 253 includes a third motor M3 and a third speed reducer G3 connected to the third motor M3. The third speed reducer G3 preferably has the same configuration as the first speed reducer G1. That is, the third speed reducer G3 is preferably configured such that the input shaft A3m and the output shaft A3g intersect. The input shaft A3m corresponds to the rotation shaft of the third motor M3. The third speed reducer G3 is preferably composed of a rolling contact transmission mechanism such as the roller gear cam reducer 10.

[0047] As described above, the roller gear cam reducer 10 is characterized by high positional accuracy and large size. If the roller gear cam reducer 10 is used in the first to third drive devices 251 to 253 close to the base 210 of the robot, the positional accuracy of the end effector can be improved. This point is almost the same as that of the first embodiment described above.

[0048] As the drive device for the fourth joint J4 to the sixth joint J6, any drive device can be used. However, it is preferable that the speed reducer of the drive device for the fourth joint J4 to the sixth joint J6 is also configured such that the input shaft A3m and the output shaft A3g intersect. In particular, it is preferably configured using a rolling contact transmission mechanism. Since the rolling contact transmission mechanism has almost no backlash, it is possible to improve the position accuracy of the hand.

[0049] In the fourth embodiment, as in the first embodiment, the first drive device 251 is configured using the first speed reducer G1 in which the input shaft and the output shaft intersect. Therefore, high position accuracy can be ensured when performing an operation of holding a workpiece. Also, in the fourth embodiment, the second drive device 252 is configured using the second speed reducer G2 in which the input shaft and the output shaft intersect. Therefore, the position accuracy can be further improved. Furthermore, in the fourth embodiment, the third drive device 253 is configured using the third speed reducer G3 in which the input shaft and the output shaft intersect. Therefore, the position accuracy can be further improved.

[0050] E. Fifth Embodiment: FIG. 11 is an explanatory diagram showing the configuration of the six-axis robot 202 in the fifth embodiment. The fifth embodiment differs from the fourth embodiment only in the following two points, and the other configurations are the same as those in the fourth embodiment. (1) The point that the sixth drive device 256 that drives the sixth joint J6 is clearly shown. (2) The point that the illustrations of the second drive device 252 and the third drive device 253 are omitted.

[0051] Each drive device for the second joint J2 to the fifth joint J5 can be configured using an arbitrary speed reducer.

[0052] The sixth drive device 256 is provided on the fifth arm 225. The sixth drive device 256 includes a sixth motor M6 and a sixth speed reducer G6 connected to the sixth motor M6. The sixth speed reducer G6 is configured such that the input shaft A6m and the output shaft A6g are parallel. The input shaft A6m and the output shaft A6g are preferably on the same straight line. The input shaft A6m corresponds to the rotation shaft of the sixth motor M6. The sixth speed reducer G6 is preferably composed of a rolling contact transmission mechanism such as a traction drive unit 20 or a harmonic gear speed reducer.

[0053] In the fifth embodiment, since the sixth speed reducer G6 with parallel input and output shafts is used, the end effector of the robot can be lightened. As a result, the energy saving performance can be improved. Further, in the fifth embodiment, since speed reducers with good positional accuracy are used for the first drive device 251 and the sixth drive device 256, which particularly require high accuracy, the positional accuracy of the end effector can be efficiently increased.

[0054] · Other embodiments: The present disclosure is not limited to the above-described embodiments, and can be realized in various forms without departing from the gist thereof. For example, the present disclosure can also be realized by the following aspects. The technical features in the above-described embodiments corresponding to the technical features in each of the following aspects can be appropriately replaced or combined in order to solve part or all of the problems of the present disclosure or to achieve part or all of the effects of the present disclosure. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0055] (1) According to one aspect of the present disclosure, an articulated robot is provided. This articulated robot includes a base, a first arm connected to the base and rotatably driven with respect to the base, and a first drive device that rotates the first arm with respect to the base. The first drive device includes a first motor and a first speed reducer, and the rotation shaft of the first motor and the output shaft of the first speed reducer intersect. According to this articulated robot, since the first drive device in which the rotation axis of the first motor and the output axis of the first speed reducer intersect is used, high positional accuracy can be ensured when holding a workpiece.

[0056] (2) In the above articulated robot, the first speed reducer may be a roller gear cam speed reducer. According to this articulated robot, since backlash in the first speed reducer can be reduced, positional accuracy can be further improved.

[0057] (3) The above articulated robot further includes a second arm connected to the first arm, and a second drive device that rotates the second arm with respect to the first arm. The second drive device has a second motor and a second speed reducer, and the rotation axis of the second motor and the output axis of the second speed reducer may intersect. According to this articulated robot, positional accuracy can be further improved.

[0058] (4) In the above articulated robot, the second drive device may be provided on the first arm. According to this articulated robot, compared with the case where the second drive device is provided on the second arm, the center of gravity of the robot is lowered, so the sway is reduced and the positional accuracy can be further improved.

[0059] (5) The above articulated robot further includes a shaft provided at the tip of the second arm, and a third drive device that moves the shaft up and down. The third drive device has a third motor and a third speed reducer, and the rotation axis of the third motor and the output axis of the third speed reducer may intersect. According to this articulated robot, since the third motor can be arranged in a lying state, the overall height of the robot can be reduced.

[0060] (6) In the above articulated robot, each of the second speed reducer and the third speed reducer is a roller gear cam speed reducer, and the second speed reducer and the third speed reducer may be provided on the second arm. According to this articulated robot, the first arm can be hollowed out, facilitating wiring. Also, the overall size of the robot can be reduced.

[0061] (7) In the above-mentioned articulated robot, the first drive device is provided on the base, the second drive device is provided on the second arm, and each of the first reduction gear and the second reduction gear may be a roller gear cam reduction gear having a turret with a hollow portion and a roller gear cam that engages with the outer periphery of the turret. Also, the electrical wiring provided inside the second arm may be arranged such that (i) it passes through the hollow portion of the turret of the second reduction gear and enters from the second arm into the first arm, (ii) it passes through the inside of the first arm and reaches above the base, and (iii) it passes through the hollow portion of the turret of the first reduction gear and reaches inside the base. According to this articulated robot, since the electrical wiring can be arranged to pass through the inside of the first arm, it is possible to reduce the amount of wiring arranged outside the robot arm.

[0062] (8) The above-mentioned articulated robot further includes a second arm connected to the first arm and a second drive device that rotates the second arm with respect to the first arm. The second drive device may have a second motor and a second reduction gear, and the rotation axis of the second motor and the output axis of the second reduction gear may be parallel. According to this articulated robot, since the end effector is lightweight, energy efficiency can be improved.

[0063] The present disclosure can also be realized in various forms other than the above. For example, it can be realized in the form of a robot system including a robot and a robot control device, a computer program for realizing the functions of the robot control device, a non-transitory storage medium recording the computer program, and the like.

Description of Reference Numerals

[0064] 10… Roller gear cam reducer, 11… Roller gear cam, 12… Turret, 13… Hollow part, 20… Traction drive unit, 21… Fixed ring, 22… Planet roller, 23… Sun shaft, 101~103… Scalar robot, 110… Base, 121… First arm, 122… Second arm, 130… Shaft, 133… Ball screw groove, 134… Spline groove, 140… Electrical wiring, 151… First drive device, 152… Second drive device, 153… Third drive device, 154… Fourth drive device, 160… Electrical wiring, 201~202… 6-axis robot, 210… Base, 221… First arm, 222… Second arm, 223… Third arm, 224… Fourth arm, 225… Fifth arm, 226… Arm end, 251… First drive device, 252… Second drive device, 253… Third drive device, 256… Sixth drive device

Claims

1. A multi-joint robot, comprising: a base; a first arm connected to the base and rotatably driven with respect to the base; a first driving device for rotating the first arm with respect to the base; wherein the first driving device includes a first motor and a first speed reducer, and an intersection angle is formed between the rotation axis of the first motor and the output axis of the first speed reducer.

2. The multi-joint robot according to claim 1, wherein the first speed reducer is a roller gear cam speed reducer.

3. The multi-joint robot according to claim 1, further comprising: a second arm connected to the first arm; a second driving device for rotating the second arm with respect to the first arm; wherein the second driving device includes a second motor and a second speed reducer, and an intersection angle is formed between the rotation axis of the second motor and the output axis of the second speed reducer.

4. The multi-joint robot according to claim 3, wherein the second driving device is provided on the first arm.

5. The multi-joint robot according to claim 3, further comprising: a shaft provided at a tip portion of the second arm; a third driving device for moving the shaft in a vertical direction; wherein the third driving device includes a third motor and a third speed reducer, and an intersection angle is formed between the rotation axis of the third motor and the output axis of the third speed reducer.

6. The multi-joint robot according to claim 5, wherein each of the second speed reducer and the third speed reducer is a roller gear cam speed reducer, and the second speed reducer and the third speed reducer are provided on the second arm.

7. The multi-joint robot according to claim 3, wherein the first driving device is provided on the base, the second driving device is provided on the second arm, each of the first speed reducer and the second speed reducer is a roller gear cam speed reducer having a hollow turret and a roller gear cam engaged with an outer periphery of the turret, and electrical wiring provided in the second arm is (i) arranged to pass through the hollow portion of the turret of the second speed reducer, enter from the second arm into the first arm, (ii) pass through the inside of the first arm and reach above the base, (iii) pass through the hollow portion of the turret of the first speed reducer and reach inside the base.

8. The articulated robot according to claim 1, further comprising: a second arm connected to the first arm; a second driving device for rotating the second arm with respect to the first arm; and the second driving device includes a second motor and a second speed reducer; an articulated robot in which a rotation axis of the second motor and an output axis of the second speed reducer are parallel.

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