Robot and robot system

Abstract

To provide a robot and a robot system having a second arm with good weight balance.SOLUTION: In a planar view from a direction along a second rotation axis, when a straight line crossing the second rotation axis and a third rotation axis is defined as a virtual center axis of a second arm, a first motor and an intermediate pulley are positioned at one side of the virtual center axis, a second motor is positioned at the other side, and a penetration hole penetrating through an arm base in a direction along the second rotation axis, is formed in the arm base. The penetration hole is arranged to be biased toward the one side of the virtual center axis, in a planar view from the direction along the second rotation axis.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] The robot described in Patent Document 1 is a SCARA robot that includes a base, a first arm rotatably connected to the base about a first rotation axis that is vertical to the base, a second arm rotatably connected to the first arm about a second rotation axis that is vertical to the first arm, and a work head disposed on the second arm. The work head also includes a spline nut and a ball screw nut that are coaxially arranged side by side in the vertical direction, and a spline shaft that is inserted through the spline nut and the ball screw nut. In this work head, when the spline nut is rotated, the spline shaft rotates about a third rotation axis that is its central axis and is vertical and moves linearly along the third rotation axis, and when the ball screw nut is rotated, the spline shaft moves linearly along the third rotation axis.

[0003] The robot also has a first spline shaft drive mechanism that rotates the spline nut to rotate the spline shaft about the third rotation axis. The first spline shaft drive mechanism has a first motor, a drive pulley fixed to the rotation axis of the first motor, a driven pulley fixed to the spline nut, an intermediate pulley located between the drive pulley and the driven pulley and rotating about a fourth rotation axis along the vertical direction, a first belt that is wound around the drive pulley and the intermediate pulley, and a second belt that is wound around the intermediate pulley and the driven pulley.

[0004] The robot also has a second spline shaft drive mechanism that rotates the ball screw nut to linearly move the spline shaft along the third rotation axis. The second spline shaft drive mechanism has a second motor, a drive pulley fixed to the rotation axis of the second motor, a driven pulley fixed to the ball screw nut, and a belt that is wound around the drive pulley and the driven pulley. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-079111 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when viewed in a plane from a direction along the second rotation axis, if the line intersecting the second rotation axis and the third rotation axis is taken as the virtual center axis of the second arm, in the robot of Patent Document 1, the intermediate pulley included only in the spline shaft first drive mechanism is positioned biased to one side of the virtual center axis, and therefore the weight of the intermediate pulley causes a large difference in weight between one side and the other side of the virtual center axis, which could reduce the drive accuracy of the second arm. [Means for solving the problem]

[0007] The robot of the present invention comprises: a base; a first arm connected to the base and rotatable about a first rotation axis relative to the base; a second arm including an arm base connected to the first arm and rotating relative to the first arm about a second rotation axis parallel to the first rotation axis; a working head that is disposed on the second arm and includes a spline shaft that extends along a third rotation axis parallel to the first rotation axis, and a spline nut and a ball screw nut that are attached to the spline shaft, wherein the spline shaft rotates about the third rotation axis when the spline nut is rotated, and the spline shaft moves linearly along the third rotation axis when the ball screw nut is rotated; a first spline shaft drive mechanism that is disposed within the second arm and that rotates the spline nut to rotate the spline shaft about the third rotation axis, and a second spline shaft drive mechanism that rotates the ball screw nut to linearly move the spline shaft along the third rotation axis, the first spline shaft drive mechanism includes a first motor fixed to the arm base, a first pulley fixed to a rotation shaft of the first motor, a second pulley fixed to the spline nut, an intermediate pulley that rotates around a fourth rotation shaft parallel to the first rotation shaft with respect to the arm base, a first belt that is wound around the first pulley and the intermediate pulley, and a second belt that is wound around the intermediate pulley and the second pulley, the second spline shaft drive mechanism includes a second motor fixed to the arm base, a third pulley fixed to a rotation shaft of the second motor, a fourth pulley fixed to the ball screw nut, and a third belt looped around the third pulley and the fourth pulley, when a straight line intersecting the second rotation shaft and the third rotation shaft is defined as a virtual center axis of the second arm in a plan view from a direction along the second rotation shaft, the first motor and the intermediate pulley are located on one side of the virtual center axis, and the second motor is located on the other side of the virtual center axis, A through hole is formed in the arm base, penetrating the arm base in a direction along the second rotation axis, and the through hole is positioned biased toward one side of the virtual center axis when viewed in a plan view from a direction along the second rotation axis.

[0008] The robot system of the present invention comprises: a robot; a control device that controls the driving of the robot, The robot includes a base and a first arm connected to the base and rotatable about a first rotation axis relative to the base; a second arm including an arm base connected to the first arm and rotating relative to the first arm about a second rotation axis parallel to the first rotation axis; a working head that is disposed on the second arm and includes a spline shaft that extends along a third rotation axis parallel to the first rotation axis, and a spline nut and a ball screw nut that are attached to the spline shaft, wherein the spline shaft rotates about the third rotation axis when the spline nut is rotated, and the spline shaft moves linearly along the third rotation axis when the ball screw nut is rotated; a first spline shaft drive mechanism that is disposed within the second arm and that rotates the spline nut to rotate the spline shaft about the third rotation axis, and a second spline shaft drive mechanism that rotates the ball screw nut to linearly move the spline shaft along the third rotation axis, the first spline shaft drive mechanism includes a first motor fixed to the arm base, a first pulley fixed to a rotation shaft of the first motor, a second pulley fixed to the spline nut, an intermediate pulley that rotates around a fourth rotation shaft parallel to the first rotation shaft with respect to the arm base, a first belt that is wound around the first pulley and the intermediate pulley, and a second belt that is wound around the intermediate pulley and the second pulley, the second spline shaft drive mechanism includes a second motor fixed to the arm base, a third pulley fixed to a rotation shaft of the second motor, a fourth pulley fixed to the ball screw nut, and a third belt looped around the third pulley and the fourth pulley, when a straight line intersecting the second rotation shaft and the third rotation shaft is defined as a virtual center axis of the second arm in a plan view from a direction along the second rotation shaft, the first motor and the intermediate pulley are located on one side of the virtual center axis, and the second motor is located on the other side of the virtual center axis, A through hole is formed in the arm base, penetrating the arm base in a direction along the second rotation axis, and the through hole is positioned biased toward one side of the virtual center axis when viewed in a plan view from a direction along the second rotation axis. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a side view showing a robot according to a first embodiment. [Figure 2] FIG. 4 is a cross-sectional view showing a connecting portion between the base and the first arm. [Figure 3] FIG. 4 is a cross-sectional view of the second arm as viewed from one lateral side. [Figure 4] FIG. 10 is a cross-sectional view of the second arm as viewed from the other lateral side. [Figure 5] FIG. 2 is an enlarged perspective view showing a tip portion of the frame. [Figure 6] FIG. 4 is a top view showing the inside of the second arm. [Figure 7] FIG. 3 is an enlarged cross-sectional view of an intermediate pulley. [Figure 8] FIG. 3 is an enlarged cross-sectional view showing the tip of the frame. [Figure 9] FIG. 10 is a top view illustrating the arrangement of through holes formed in the arm base. [Figure 10] FIG. 10 is a top view showing the inside of a second arm of a robot according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A robot and a robot system according to the present invention will be described in detail below based on embodiments shown in the accompanying drawings.

[0011] First Embodiment FIG. 1 is a side view showing a robot according to a first embodiment. FIG. 2 is a cross-sectional view showing a connection portion between a base and a first arm. FIG. 3 is a cross-sectional view of a second arm seen from one lateral side. FIG. 4 is a cross-sectional view of a second arm seen from the other lateral side. FIG. 5 is an enlarged perspective view of a tip portion of a frame. FIG. 6 is a top view showing the inside of the second arm. FIG. 7 is an enlarged cross-sectional view of an intermediate pulley. FIG. 8 is an enlarged cross-sectional view of a tip portion of a frame. FIG. 9 is a top view for explaining the arrangement of through holes formed in an arm base.

[0012] The up-down direction in FIG. 1 corresponds to the vertical direction. Therefore, hereinafter, the upper side in FIG. 1 will also be referred to as "upper" and the lower side as "lower." Furthermore, in this specification, "vertical" refers not only to the case where the two objects are aligned vertically, but also to the case where the two objects are inclined relative to the vertical within a range where the effects of the present invention can be achieved, for example, the case where the two objects are inclined within ±5° of the vertical. Similarly, in this specification, "parallel" refers not only to the case where two objects are aligned parallel to each other, but also to the case where the two objects are inclined from the parallel direction within a range where the effects of the present invention can be achieved, for example, the case where the two objects are inclined within ±5° of the parallel direction.

[0013] The robot system 100 shown in FIG. 1 includes a robot 1 and a control device 9 that controls the driving of the robot 1.

[0014] <Control device 9> 1, the control device 9 includes, for example, a control board 91 and a power supply board 92. However, without being limited to this, the control board 91 and the power supply board 92 may be integrated into one board.

[0015] The control board 91 controls the overall operation of each part of the robot 1. The control board 91 is equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc. The CPU reads and executes programs and data stored in the ROM, thereby achieving the above-mentioned functions. The control board 91 is also electrically connected to a host computer (not shown), and controls the operation of each part of the robot 1 based on commands from the host computer. However, this is not limiting, and the circuits of the control board 91 may be separated into multiple boards.

[0016] The power supply board 92 supplies power to the control board 91. The power supply board 92 is equipped with a conversion circuit that converts externally supplied power into a predetermined value and supplies it to the control board 91. The conversion circuit varies depending on the configuration of the robot 1, but examples include an AC / DC conversion circuit that converts an alternating current (AC) signal into a direct current (DC) signal, and a step-up circuit or step-down circuit that converts the voltage level of a signal. However, the invention is not limited to this, and the circuits of the power supply board 92 may be separated into multiple boards.

[0017] However, the configuration of the control device 9 is not particularly limited as long as it can control the driving of the robot 1. Furthermore, in this embodiment, the control device 9 is disposed inside the base 10 of the robot 1, but the location of the control device 9 is not particularly limited. For example, the control device 9 may be installed outside the base 10. In this case, the robot 1 and the control device 9 may be connected by a cable or wirelessly.

[0018] <Robot 1> The robot 1 is a horizontal articulated robot (SCARA robot). As shown in Fig. 1, the robot 1 has a base 10 fixed to the floor or the like, a first arm 11 rotatably connected to the base 10, a second arm 12 rotatably connected to the first arm 11, a work head 13 disposed on the second arm 12, and a duct 14 connecting the base 10 and the second arm 12.

[0019] As shown in FIG. 2, the first arm 11 is connected at its base end to the base 10 and rotates about a first rotation axis J1 that is perpendicular to the base 10.

[0020] 3 and 4, the second arm 12 is connected at its base end to the first arm 11 and rotates relative to the first arm 11 around a second rotation axis J2 that is parallel to the first rotation axis J1. The second arm 12 also has a rigid arm base 121 connected to the first arm 11, a frame 122 fixed to the arm base 121, and a cover 123 that covers the arm base 121 from above the frame 122. For example, the arm base 121 and the frame 122 are made of a lightweight and rigid metal material such as aluminum, and the cover 123 is made of a lightweight resin material.

[0021] Furthermore, frame 122 is a cantilever beam having a base end fixed to arm base 121 and a tip end that is a free end separated from arm base 121. Duct 14 is connected to frame 122. Also, a connector 181 and a brake release button 17 that releases brake 243 (described later) are disposed on frame 122. Connector 181 and brake release button 17 are exposed to the outside of second arm 12 without being covered by cover 123. As shown in FIG. 1 , connector 182 that forms a pair with connector 181 is disposed on the back surface of base 10, and connectors 181 and 182 are connected to each other via wiring 31.

[0022] Also, a lens 85 that shines when light L from a light-emitting element 82 described later is incident on the frame 122. The lens 85 is not covered by the cover 123, but is exposed to the outside of the second arm 12.

[0023] 6, the tip of the frame 122 is supported by the arm base 121 via a pair of support members 41 and 42. As described above, the frame 122 is a cantilever beam, and therefore the tip side is prone to bending up and down. Therefore, for example, when a user inserts a connector into the connector 181, presses the brake release button 17, or installs wiring or a device connected to the connector 181 on the frame 122, stress may be applied to the frame 122, which may cause plastic deformation. Therefore, by supporting the tip of the frame 122 with the pair of support members 41 and 42, deformation of the frame 122 can be effectively suppressed.

[0024] As shown in FIG. 1 , the duct 14 is a tubular member disposed outside the first arm 11 and directly connects the base 10 and the second arm 12 without passing through the first arm 11. As shown in FIGS. 2 to 4 , the duct 14 has a base end connected to the base 10 and a tip end connected to the second arm 12, and has a base end opening 141 facing the inside of the base 10 and a tip end opening 142 facing the inside of the second arm 12. This allows communication between the base 10 and the second arm 12 via the duct 14. A plurality of wires 31 are routed between the base 10 and the second arm 12 via the duct 14, and the electronic components disposed on the second arm 12 and the electronic components disposed on the base 10 are electrically connected via these wires 31, as with the connectors 181 and 182 described above. The wires 31 are routed, for example, through a gap between the motors 231 and 241, toward the tip side of the motors 231 and 241.

[0025] 3 and 4, the working head 13 is disposed at the tip of the second arm 12. The working head 13 also has a spline nut 131 and a ball screw nut 132 that are coaxially arranged side by side in the vertical direction, and a spline shaft 133 that is inserted through the spline nut 131 and the ball screw nut 132. In this working head 13, when the spline nut 131 is rotated, the spline shaft 133 rotates about a third rotation axis J3 that is its central axis and is parallel to the first rotation axis J1, and also moves linearly (up and down) along the third rotation axis J3; when the ball screw nut 132 is rotated, the spline shaft 133 moves linearly along the third rotation axis J3; and when both the spline nut 131 and the ball screw nut 132 are rotated, the spline shaft 133 rotates about the third rotation axis J3. Although not shown, an end effector suitable for the work is attached to the lower end of the spline shaft 133.

[0026] As shown in Figures 2 and 3, the robot 1 also has a first arm drive mechanism 21 that rotates the first arm 11 around a first rotation axis J1 relative to the base 10, and a second arm drive mechanism 22 that rotates the second arm 12 around a second rotation axis J2 relative to the first arm 11.

[0027] As shown in FIG. 2, the first arm drive mechanism 21 includes a reducer 211 that rotatably connects the base 10 and the first arm 11, and a motor 212 with a built-in encoder that is disposed within the base 10. The motor 212 is a servo motor, particularly a three-phase motor driven by three-phase AC, and is fixed to the base 10. The reducer 211 is a harmonic gear device, and a circular spline 211a is fixed to the base 10 and a flexspline 211b is fixed to the first arm 11. The rotation shaft of the motor 212 is fixed to a wave generator 211c. Therefore, the wave generator 211c rotates with the rotation of the motor 212, and further, the flexspline 211b rotates at a predetermined reduction ratio relative to the rotation of the wave generator 211c. As a result, the first arm 11 rotates around the first rotation axis J1 relative to the base 10. However, the configuration of the first arm driving mechanism 21 is not particularly limited.

[0028] The second arm drive mechanism 22 has a configuration similar to that of the first arm drive mechanism 21. As shown in FIGS. 3 and 4 , the second arm drive mechanism 22 includes a reducer 221 that rotatably connects the first arm 11 and the second arm 12, and a motor 222 with a built-in encoder that is disposed within the second arm 12. The motor 222 is a servo motor, particularly a three-phase motor that is driven by three-phase AC, and is fixed to the arm base 121. The reducer 221 is a harmonic gear device, and a circular spline 221a is fixed to the arm base 121 and a flexspline 221b is fixed to the first arm 11. The rotation shaft of the motor 222 is fixed to a wave generator 221c. Therefore, the wave generator 221c rotates as the motor 222 rotates, and the flexspline 221b rotates at a predetermined reduction ratio relative to the rotation of the wave generator 221c. As a result, the second arm 12 rotates about the second rotation axis J2 relative to the first arm 11. However, the configuration of the second arm drive mechanism 22 is not particularly limited.

[0029] As shown in Figures 3, 4 and 6, the robot 1 also has a spline shaft first drive mechanism 23 that rotates the spline nut 131 to rotate and linearly move the spline shaft 133, and a spline shaft second drive mechanism 24 that rotates the ball screw nut 132 to linearly move the spline shaft 133.

[0030] 3 and 6, the spline shaft first drive mechanism 23 has a first motor 231 with a built-in encoder disposed inside the second arm 12, and a speed reduction mechanism 232 that transmits the rotation of the first motor 231 to the spline nut 131. The first motor 231 is a servo motor, particularly a three-phase motor driven by three-phase AC, and is fixed to the arm base 121.

[0031] The reduction mechanism 232 includes a first pulley 51 fixed to the rotation shaft of the first motor 231, a second pulley 52 fixed to the spline nut 131, a support member 59 fixed to the arm base 121, an intermediate pulley 54 supported on the support member 59 via bearings 501 and 502 described later and rotating around a fourth rotation axis J4 that is vertical to the arm base 121, a first belt 55 that is routed around the first pulley 51 and the intermediate pulley 54, and a second belt 56 that is routed around the intermediate pulley 54 and the second pulley 52.

[0032] 7, the intermediate pulley 54 includes a first intermediate pulley 541, a second intermediate pulley 542 that is located below the first intermediate pulley 541, i.e., on the arm base 121 side, and has a smaller diameter than the first intermediate pulley 541, and a shaft 543 that is disposed along the fourth rotation axis J4 and connects the first intermediate pulley 541 and the second intermediate pulley 542. In the present embodiment, the second intermediate pulley 542 and the shaft 543 are integrally formed, and the shaft 543 and the first intermediate pulley 541 are fixed, but this is not limiting. The first intermediate pulley 541 and the shaft 543 may be integrally formed, and the shaft 543 and the second intermediate pulley 542 may be fixed, or the first intermediate pulley 541, the second intermediate pulley 542, and the shaft 543 may be separate bodies that are fixed to each other.

[0033] Furthermore, the lower end of the shaft portion 543 protrudes below the second intermediate pulley 542. The intermediate pulley 54 is rotatably supported at two points of the shaft portion 543 by the support member 59 via a first bearing 501 and a second bearing 502. The bearing 501 is located between the first intermediate pulley 541 and the second intermediate pulley 542, and the bearing 502 is located below the second intermediate pulley 542.

[0034] The support member 59 has a first holding portion 591 that holds a portion of the shaft portion 543 between the first intermediate pulley 541 and the second intermediate pulley 542 via a bearing 501, a second holding portion 592 that holds a portion of the shaft portion 543 below the second intermediate pulley 542 via a bearing 502, and a connecting portion 593 that connects the first holding portion 591 and the second holding portion 592. In this embodiment, the second holding portion 592 and the connecting portion 593 are integrally formed, and the connecting portion 593 and the first holding portion 591 are fixed with a screw. However, this is not limited thereto, and the first holding portion 591 and the connecting portion 593 may be integrally formed, and the connecting portion 593 and the second holding portion 592 may be fixed with a screw, or the first holding portion 591, the second holding portion 592, and the connecting portion 593 may be formed separately from one another. Furthermore, the support member 59 and the arm base 121 may be fixed with a screw. In that case, for example, through holes may be formed in the first holding portion 591, the second holding portion 592, and the connecting portion 593, and screws passing through these through holes may be fastened to the arm base 121. This makes it easy to fix the support member 59 and the arm base 121 together.

[0035] The first intermediate pulley 541 is disposed at the same height as the first pulley 51. The first intermediate pulley 541 has a larger diameter than the first pulley 51, and a first belt 55 is wound around the first pulley 51 and the first intermediate pulley 541. The first pulley 51, the first intermediate pulley 541, and the first belt 55 constitute a first reduction gear mechanism 232a in the front stage. The second intermediate pulley 542 is disposed at the same height as the second pulley 52. ​​The second intermediate pulley 542 has a smaller diameter than the second pulley 52, and a second belt 56 is wound around the second intermediate pulley 542 and the second pulley 52. ​​The second intermediate pulley 542, the second pulley 52, and the second belt 56 constitute a second reduction gear mechanism 232b in the rear stage.

[0036] In this configuration, the rotation of the first motor 231 is transmitted to the first intermediate pulley 541 via the first pulley 51 and the first belt 55, causing the first intermediate pulley 541 and the second intermediate pulley 542 to rotate together around the fourth rotation axis J4. The rotation of the second intermediate pulley 542 is transmitted to the second pulley 52 via the second belt 56, causing the second pulley 52 and the spline nut 131 to rotate together around the third rotation axis J3. As a result, the spline shaft 133 rotates around the third rotation axis J3 and moves linearly along the third rotation axis J3. In other words, it at least rotates. In this way, the reduction mechanism 232 includes the first reduction mechanism 232a and the second reduction mechanism 232b, so that the rotation of the first motor 231 can be reduced in two stages, allowing the spline nut 131 to rotate with greater torque.

[0037] As shown in FIG. 7 , the first intermediate pulley 541 includes a cylindrical belt mounting portion 541a around which the first belt 55 is wound, and a connecting portion 541b located inside the belt mounting portion 541a and connecting the shaft portion 543 to the belt mounting portion 541a. The connecting portion 541b is thin-walled and has a smaller thickness, i.e., a smaller length in the direction along the fourth rotation axis J4, than the belt mounting portion 541a. This contributes to reducing the weight of the intermediate pulley 54. Furthermore, the connecting portion 541b is formed with a lightening portion 541c constituted by a through-hole that penetrates the connecting portion 541b in the thickness direction. This contributes to further reducing the weight of the intermediate pulley 54. In particular, the first intermediate pulley 541 has a larger diameter than the second intermediate pulley 542. This contributes to a significant weight reduction of the intermediate pulley 54 by thinning the connecting portion 541b and forming the lightening portion 541c.

[0038] Furthermore, in a plan view taken along the fourth rotation axis J4, the lightening hole 541c overlaps with the screw that fastens the connecting portion 593 to the first holding portion 591. Therefore, a tool such as a screwdriver can be inserted into the lightening hole 541c to fasten the screw, facilitating the work of fastening the connecting portion 593 to the first holding portion 591.

[0039] In this embodiment, the two fan-shaped lightening portions 541c are arranged symmetrically with respect to the fourth rotation axis J4, but the shape and number of the lightening portions 541c are not particularly limited. Furthermore, the second intermediate pulley 542 may also have a lightening portion similar to that of the first intermediate pulley 541. This allows for further weight reduction of the intermediate pulley 54. Furthermore, the lightening portion 541c may be omitted.

[0040] 4 and 6, the spline shaft second drive mechanism 24 has a second motor 241 with a built-in encoder disposed inside the second arm 12, a speed reduction mechanism 242 that transmits the rotation of the second motor 241 to the ball screw nut 132, and a brake 243 for the second motor 241. The second motor 241 is a servo motor, in particular a three-phase motor that is driven by three-phase AC, and is fixed to the arm base 121.

[0041] The speed reduction mechanism 242 includes a third pulley 242a fixed to the rotation shaft of the second motor 241, a fourth pulley 242b fixed to the ball screw nut 132, and a third belt 242c wound around the third pulley 242a and the fourth pulley 242b. With this configuration, the rotation of the second motor 241 is transmitted to the fourth pulley 242b via the third pulley 242a and the third belt 242c, causing the fourth pulley 242b and the ball screw nut 132 to rotate integrally around the third rotation axis J3. This causes the spline shaft 133 to move linearly along the third rotation axis J3. Using the speed reduction mechanism 242 in this way allows the rotation of the second motor 241 to be slowed down, allowing the ball screw nut 132 to rotate with a sufficiently large torque.

[0042] As shown in FIG. 3, the third belt 242c is located between the first belt 55 and the second belt 56 in a plan view perpendicular to the fourth rotation axis J4. That is, the first belt 55 is located above the third belt 242c, and the second belt 56 is located below the third belt 242c. With this configuration, the third belt 242c can intersect with the first and second belts 55 and 56 in a plan view along the second rotation axis J2. This increases the flexibility in the placement of the intermediate pulley 54. However, the configuration of the second spline shaft drive mechanism 24 is not particularly limited. For example, the third belt 242c may be located above the first belt 55, i.e., above the intermediate pulley 54.

[0043] As shown in FIG. 4, the brake 243 is an electromagnetic brake attached to the second motor 241 and includes a pair of opposing plates 243a and 243b. One plate 243a is fixed to the second motor 241, and the other plate 243b is fixed to the rotation shaft of the second motor 241 and rotates together with the rotation shaft. By controlling the ON / OFF state of the power supply, the brake 243 switches between a brake state in which the plates 243a and 243b are in contact with each other to restrict rotation of the rotation shaft, and a brake release state in which the plates 243a and 243b are separated to allow rotation of the rotation shaft. In particular, the brake 243 of this embodiment is a non-excitation type electromagnetic brake that is in the brake release state when power is supplied (ON) and in the brake state when power is cut off (OFF). However, the configuration of the brake 243 is not particularly limited.

[0044] 5 and 8, a brake control board 8 that controls the brake 243 is fixed to the frame 122. The brake control board 8 is electrically connected to the control board 91 via wiring 31. The brake control board 8 is also electrically connected to the brake 243 via wiring 32, and is electrically connected to the brake release button 17 via wiring 33. The brake control board 8 controls the drive of the brake 243 based on a command from the control board 91, and switches between a brake state and a brake release state. The brake control board 8 also controls the drive of the brake 243 based on the operation of the brake release button 17, and switches between a brake state and a brake release state.

[0045] As shown in FIG. 8 , the robot 1 also has a light-emitting element 82 mounted on the brake control board 8. The light-emitting element 82 is, for example, an LED (Light Emitting Diode). Light L emitted from the light-emitting element 82 is diffusely reflected upward by the frame 122 and then enters the lens 85. This causes the lens 85 to illuminate. Therefore, by controlling the driving of the light-emitting element 82 and switching the lens 85 between on / blinking / off and switching the color of light emitted from the lens 85, it is possible to notify the user of various information via the lens 85.

[0046] While power is being supplied to the motors 212, 222, 231, and 241, i.e., while the robot 1 is powered on, the brake control board 8 emits light L of a predetermined color from the light-emitting element 82 to illuminate the lens 85. Hereinafter, this state will also be referred to as the first light-emitting state. This allows the user to easily be notified that the robot 1 is powered on. Furthermore, when the brake release button 17 is pressed and the brake 243 enters the brake release state, the brake control board 8 emits light L of a color different from that of the first light-emitting state from the light-emitting element 82 to illuminate the lens 85. Hereinafter, this state will also be referred to as the second light-emitting state. This allows the user to easily be notified that the brake 243 is in the brake release state. However, the notification method is not particularly limited. For example, the first light-emitting state may be illuminated and the second light-emitting state may be extinguished, or the first light-emitting state may be illuminated and the second light-emitting state may be flashing.

[0047] The brake control board 8 as described above includes a CPU (Central Processing Unit), a ROM (Read Only Memory), etc. The CPU reads and executes programs and data stored in the ROM, thereby achieving the above-mentioned functions.

[0048] 3, 4, and 6, the robot 1 has a mounting member 16 disposed within the second arm 12 and on which an inertial sensor module 6 for measuring the inertia of the second arm 12 is mounted. The mounting member 16 is fixed to the arm base 121 via a plurality of support columns 165, and is positioned above the second belt 56 and the third belt 242c.

[0049] The inertial sensor module 6 includes a substrate 61 fixed to the mounting member 16 via multiple spacers 164 and an angular velocity sensor 62 mounted on the substrate 61 and configured to detect the angular velocity of the second arm 12 around the vertical axis. The angular velocity sensor 62 also includes a package and an angular velocity sensor element and a circuit element housed within the package. The angular velocity sensor element is, for example, a quartz oscillator. The angular velocity sensor element includes a drive arm that is driven to vibrate when a drive signal is applied, and a detection arm that detects vibrations due to the Coriolis force generated by the angular velocity and outputs a signal of a magnitude corresponding to the drive arm. The circuit element includes, for example, a drive circuit that applies a drive signal to vibrate the drive arm of the quartz oscillator, and a detection circuit that detects the angular velocity based on the signal output from the detection arm. The inertial sensor module 6 is positioned so as to overlap with a virtual central axis A (described later) when viewed from a plane along the second rotation axis J2. However, this is not limiting, and the inertial sensor module 6 may also be positioned so as not to overlap with the virtual central axis A.

[0050] Furthermore, a control circuit (not shown) is formed on the substrate 61 to control the driving of the angular velocity sensor 62 based on commands from the control substrate 91. The control circuit includes a CPU (Central Processing Unit), a ROM (Read Only Memory), etc., and the CPU reads and executes programs and data stored in the ROM to achieve the above-mentioned functions.

[0051] However, the inertial sensor module 6 is not particularly limited. For example, in this embodiment, the inertial sensor is an angular velocity sensor that detects the angular velocity of the second arm 12, but is not limited to this and may be, for example, an acceleration sensor that detects the acceleration of the second arm 12. It may also be a composite sensor that can detect both angular velocity and acceleration. Furthermore, in this embodiment, the angular velocity sensor element is a quartz crystal resonator, but is not limited to this and may be, for example, a silicon MEMS that detects angular velocity based on changes in electrostatic capacitance between a movable electrode and a fixed electrode.

[0052] 3 and 4, an insertion hole 123a for inserting the spline shaft 133 is formed in the cover 123 of the second arm 12. Due to the vertical linear movement of the spline shaft 133, an airflow is generated between the insertion hole 123a and a through-hole 121a (described later) formed in the arm base 121. If this airflow collides with the inertial sensor module 6, the inertial sensor module 6 may vibrate, resulting in a decrease in the angular velocity detection accuracy. Therefore, a guide wall 123b for guiding the airflow is formed between the spline shaft 133 of the cover 123 and the inertial sensor module 6. This makes it difficult for the airflow to collide with the inertial sensor module 6, thereby effectively preventing a decrease in the angular velocity detection accuracy of the inertial sensor module 6.

[0053] This concludes the description of the overall configuration of the robot 1. Next, we will explain the arrangement of each part included in the first spline shaft drive mechanism 23 and the second spline shaft drive mechanism 24. Note that, hereinafter, the line intersecting the second rotation axis J2 and the third rotation axis J3 in a plan view from a direction along the second rotation axis J2 will also be referred to as the imaginary central axis A of the second arm 12.

[0054] As shown in FIG. 9 , in a plan view taken along the second rotation axis J2, the first motor 231 and the intermediate pulley 54 of the first spline shaft drive mechanism 23 are disposed on one side of the imaginary central axis A, and the second motor 241 of the second spline shaft drive mechanism 24 is disposed on the other side of the imaginary central axis A. Note that "the first motor 231 and the intermediate pulley 54 are disposed on one side of the imaginary central axis A" means that the central axis of the rotation axis of the first motor 231 and the fourth rotation axis J4 are located on one side of the imaginary central axis A. Therefore, as long as the above-described positional relationship is satisfied, the entire area of ​​the first motor 231 and the intermediate pulley 54 may be located on one side of the imaginary central axis A, or they may be located across both sides of the imaginary central axis A. Similarly, "the second motor 241 is disposed on the other side of the imaginary central axis A" means that the central axis of the rotation axis of the second motor 241 is located on the other side of the imaginary central axis A. Therefore, as long as the above positional relationship is satisfied, the entire area of ​​the second motor 241 may be located on the other side of the imaginary central axis A, or may be located across both sides of the imaginary central axis A.

[0055] In this way, by arranging the first and second motors 231, 241, which are heavy objects, on opposite sides of the imaginary central axis A, the difference in weight between one side and the other side of the imaginary central axis A can be kept small compared to, for example, arranging the first and second motors 231, 241 on the same side of the imaginary central axis A, and deterioration of the weight balance of the second arm 12 can be suppressed. However, because the intermediate pulley 54 provided only on the first spline shaft drive mechanism 23 of the first spline shaft drive mechanism 23 and the second spline shaft drive mechanism 24 is arranged on one side of the imaginary central axis A, the one side of the imaginary central axis A becomes heavier, and the weight balance of the second arm 12 is deteriorated. Therefore, in the robot 1, a through hole 121a is formed in the arm base 121 to suppress deterioration of the weight balance due to the intermediate pulley 54. The through hole 121a will be described in detail below.

[0056] As shown in FIG. 9 , the through hole 121a is disposed offset to one side of the imaginary central axis A in a plan view from the direction along the second rotation axis J2. Note that "the through hole 121a is disposed offset to one side of the imaginary central axis A" means that the center of the through hole 121a is located on one side of the imaginary central axis A. In other words, the area of ​​the region located on one side of the imaginary central axis A is larger than the area of ​​the region located on the other side. Therefore, as long as the above-described positional relationship is satisfied, the entire through hole 121a may be disposed on one side of the imaginary central axis A, or may be disposed across both sides of the imaginary central axis A. However, in this embodiment, the entire through hole 121a is disposed on one side of the imaginary central axis A. By forming such a through hole 121a, at least a portion of the weight increase due to the intermediate pulley 54 can be canceled out by the weight reduction due to the through hole 121a on one side of the imaginary central axis A. Therefore, by forming the through hole 121a, deterioration of the weight balance of the second arm 12 can be effectively suppressed. That is, it is possible to minimize the difference in weight between one side and the other side of the imaginary central axis A. As a result, the driving accuracy of the second arm 12 is improved.

[0057] Furthermore, in a plan view taken along the second rotation axis J2, the through hole 121a is located closer to the third rotation axis J3 than the fourth rotation axis J4, that is, closer to the tip of the second arm 12. With this configuration, the weight of the tip of the second arm 12 can be reduced by the through hole 121a, and therefore the moment of inertia of the second arm 12 can be reduced.

[0058] Furthermore, in a plan view from the direction along the second rotation axis J2, the through hole 121a overlaps with the intermediate pulley 54. With this configuration, the intermediate pulley 54, which is a cause of deterioration in weight balance, and the through hole 121a, which is intended to improve weight balance, can be disposed closer to each other. This makes it possible to effectively prevent deterioration in the weight balance of the second arm 12. However, the present invention is not limited to this, and the through hole 121a does not have to overlap with the intermediate pulley 54 in a plan view from the direction along the second rotation axis J2.

[0059] As shown in FIG. 9 , the first intermediate pulley 541 is positioned above the third belt 242c and overlaps the third belt 242c in a plan view along the second rotation axis J2. By overlapping the intermediate pulley 54 and the third belt 242c in a plan view along the second rotation axis J2, the intermediate pulley 54 can be positioned as close to the imaginary central axis A as possible. This minimizes the degree of weight imbalance caused by the intermediate pulley 54, allowing the through hole 121a, which is intended to improve weight balance, to be smaller. Because there is a limit to the size of the through hole 121a that can be formed in the arm base 121, a smaller through hole 121a can be formed, making it easier to form the through hole 121a with a size commensurate with the weight imbalance caused by the intermediate pulley 54. This more effectively prevents weight imbalance of the second arm 12. Furthermore, a smaller through hole 121a can also prevent a decrease in the rigidity of the arm base 121. However, the present invention is not limited to this, and the intermediate pulley 54 does not have to overlap with the third belt 242c in a plan view along the second rotation shaft J2.

[0060] 9, the intermediate pulley 54 overlaps with the imaginary central axis A in a plan view taken along the second rotation axis J2. This configuration allows the intermediate pulley 54 to be positioned as close to the imaginary central axis A as possible. This minimizes the degree of weight imbalance caused by the intermediate pulley 54, allowing the through hole 121a, which is intended to improve the weight balance, to be smaller. Because there is a limit to the size of the through hole 121a that can be formed in the arm base 121, a smaller through hole 121a can be formed, which makes it easier to form the through hole 121a with a size commensurate with the weight imbalance caused by the intermediate pulley 54, thereby more effectively preventing the weight imbalance of the second arm 12 from being adversely affected. Furthermore, a smaller through hole 121a can also prevent a decrease in the rigidity of the arm base 121. In particular, in this embodiment, as described above, the third belt 242c is located between the first belt 55 and the second belt 56 in a plan view from a direction perpendicular to the fourth rotation axis J4, and therefore the third belt 242c can cross the first and second belts 55, 56. This increases the degree of freedom in arranging the intermediate pulley 54, making it easier to arrange the intermediate pulley 54 closer to the imaginary central axis A. However, this is not limiting, and the intermediate pulley 54 does not have to overlap with the imaginary central axis A in a plan view from a direction along the second rotation axis J2.

[0061] In this way, in the robot 1, the intermediate pulley 54 is arranged to overlap the third belt 242c and the imaginary central axis A in a plan view along the second rotation axis J2, thereby minimizing the degree of weight imbalance caused by the intermediate pulley 54. In addition, in this embodiment, as described above, the weight of the intermediate pulley 54 is reduced by forming the hollowed-out portion 541c in the first intermediate pulley 541. Furthermore, the support member 59 that supports the intermediate pulley 54 is configured to support both the upper and lower sides of the second intermediate pulley 542, which is located lower among the vertically arranged first and second intermediate pulleys 541 and 542, thereby keeping the center of gravity of the support member 59 low. These configurations also minimize the degree of weight imbalance caused by the intermediate pulley 54. In this way, in the robot 1, the degree of weight imbalance caused by the intermediate pulley 54 is minimized not only by the arrangement of the intermediate pulley 54, but also by reducing the weight of the intermediate pulley 54 itself and by devising the configuration of the support member 59 that supports the intermediate pulley 54.

[0062] 9, in the robot 1, the mounting member 16 overlaps with the imaginary central axis A in a plan view taken along the second rotation axis J2. By arranging the mounting member 16 in this manner, it is possible to prevent the weight balance of the second arm 12 from being adversely affected by the mounting member 16.

[0063] The robot system 100 has been described above. As described above, the robot 1 included in the robot system 100 includes the base 10, the first arm 11 connected to the base 10 and rotatable about a first rotation axis J1 relative to the base 10, the arm base 121 connected to the first arm 11, the second arm 12 rotatable about a second rotation axis J2 parallel to the first rotation axis J1 relative to the first arm 11, the spline shaft 133 disposed on the second arm 12 and extending along a third rotation axis J3 parallel to the first rotation axis J1, and the spline nut 131 and the ball screw nut 132 attached to the spline shaft 133. The working head 13 includes: a working head 13 that rotates the spline shaft 133 at least around the third rotation axis J3 when the line nut 131 is rotated; and a working head 13 that moves the spline shaft 133 linearly along the third rotation axis J3 when the ball screw nut 132 is rotated; and a spline shaft first drive mechanism 23 that is disposed within the second arm 12 and rotates the spline nut 131 to rotate the spline shaft 133 at least around the third rotation axis J3; and a spline shaft second drive mechanism 24 that rotates the ball screw nut 132 to move the spline shaft 133 linearly along the third rotation axis J3. The spline shaft first drive mechanism 23 also has a first motor 231 fixed to the arm base 121, a first pulley 51 fixed to the rotating shaft of the first motor 231, a second pulley 52 fixed to the spline nut 131, an intermediate pulley 54 that rotates around a fourth rotating axis J4 parallel to the first rotating axis J1 relative to the arm base 121, a first belt 55 that is looped around the first pulley 51 and the intermediate pulley 54, and a second belt 56 that is looped around the intermediate pulley 54 and the second pulley 52. The spline shaft second drive mechanism 24 also has a second motor 241 fixed to the arm base 121, a third pulley 242a fixed to the rotation shaft of the second motor 241, a fourth pulley 242b fixed to the ball screw nut 132, and a third belt 242c passed around the third pulley 242a and the fourth pulley 242b.Furthermore, when viewed from above in a direction along the second rotation axis J2, if a line intersecting the second rotation axis J2 and the third rotation axis J3 is defined as an imaginary center axis A of the second arm 12, the first motor 231 and the intermediate pulley 54 are located on one side of the imaginary center axis A, and the second motor 241 is located on the other side. Furthermore, the arm base 121 is formed with a through-hole 121a penetrating the arm base 121 in a direction along the second rotation axis J2, and the through-hole 121a is biased toward one side of the imaginary center axis A, i.e., toward the side where the intermediate pulley 54 is located. With this configuration, at least a portion of the weight increase due to the intermediate pulley 54 on one side of the imaginary center axis A can be canceled out by the weight reduction due to the through-hole 121a. Therefore, by forming the through-hole 121a, deterioration of the weight balance of the second arm 12 can be effectively suppressed. In other words, the difference in weight between one side and the other side of the imaginary center axis A can be kept small. As a result, the driving accuracy of the second arm 12 is improved.

[0064] As described above, the third rotation axis J3 is located closer to the tip of the second arm 12 than the fourth rotation axis J4, and the through-hole 121a is located closer to the third rotation axis J3 than the fourth rotation axis J4 in a plan view taken along the second rotation axis J2. This configuration reduces the weight of the tip of the second arm 12, thereby reducing the moment of inertia of the second arm 12.

[0065] As described above, the through hole 121a and the intermediate pulley 54 overlap in a plan view taken along the second rotation axis J2. This configuration allows the intermediate pulley 54, which is a factor in weight imbalance, and the through hole 121a, which is used to improve weight balance, to be positioned closer together. This effectively prevents weight imbalance of the second arm 12 from occurring.

[0066] As described above, the intermediate pulley 54 and the third belt 242c overlap in a plan view taken along the second rotation axis J2. This configuration allows the intermediate pulley 54 to be positioned as close as possible to the imaginary central axis A. This minimizes the degree of weight imbalance caused by the intermediate pulley 54, allowing the through hole 121a, which is intended to improve the weight balance, to be smaller. Because there is a limit to the size of the through hole 121a that can be formed in the arm base 121, a smaller through hole 121a can be formed, which makes it easier to form the through hole 121a with a size commensurate with the weight imbalance caused by the intermediate pulley 54, thereby more effectively preventing the weight imbalance of the second arm 12 from being adversely affected. Furthermore, a smaller through hole 121a can also prevent a decrease in the rigidity of the arm base 121.

[0067] As described above, the intermediate pulley 54 and the imaginary central axis A overlap in a plan view taken along the second rotation axis J2. This configuration allows the intermediate pulley 54 to be positioned as close as possible to the imaginary central axis A. This minimizes the degree of weight imbalance caused by the intermediate pulley 54, allowing the through hole 121a, which is intended to improve the weight balance, to be smaller. Because there is a limit to the size of the through hole 121a that can be formed in the arm base 121, a smaller through hole 121a can be formed, which makes it easier to form the through hole 121a with a size commensurate with the weight imbalance caused by the intermediate pulley 54, thereby more effectively preventing the weight imbalance of the second arm 12 from worsening. Furthermore, a smaller through hole 121a can also prevent a decrease in the rigidity of the arm base 121.

[0068] As described above, the intermediate pulley 54 includes a shaft portion 543 extending along the fourth rotation axis J4, a first intermediate pulley 541 disposed on the shaft portion 543 and around which the first belt 55 is wound, and a second intermediate pulley 542 disposed on the shaft portion 543, located closer to the arm base 121 than the first intermediate pulley 541, and around which the second belt 56 is wound. The robot 1 also includes a support member 59 fixed to the arm base 121, which supports a portion of the shaft portion 543 between the first intermediate pulley 541 and the second intermediate pulley 542 via a first bearing 501 and a portion of the shaft portion 543 closer to the arm base 121 than the second intermediate pulley 542 via a second bearing 502. The support member 59 configured in this manner can lower the center of gravity of the support member 59. This minimizes the degree of weight imbalance caused by the intermediate pulley 54.

[0069] Furthermore, as described above, the third belt 242c is located between the first belt 55 and the second belt 56 in a plan view from a direction perpendicular to the fourth rotation axis J4. With this configuration, the third belt 242c can intersect with the first and second belts 55, 56 in a plan view from a direction along the second rotation axis J2. This increases the degree of freedom in the placement of the intermediate pulley 54, making it easier to place the intermediate pulley 54 closer to the imaginary central axis A.

[0070] As described above, the first intermediate pulley 541 has a larger diameter than the second intermediate pulley 542, and the first intermediate pulley 541 has a lightening portion 541c that penetrates the first intermediate pulley 541 in the direction along the fourth rotation shaft J4. With this configuration, the weight of the intermediate pulley 54 can be reduced, and the degree of deterioration of the weight balance caused by the intermediate pulley 54 can be kept small.

[0071] As described above, the robot 1 is provided with the mounting member 16, which is disposed on the second arm 12 and on which the inertial sensor module 6 for measuring the inertia of the second arm 12 is mounted. The mounting member 16 overlaps with the imaginary central axis A in a plan view taken along the second rotation axis J2. This configuration can prevent the weight balance of the second arm 12 from being adversely affected by the mounting member 16.

[0072] As described above, the robot system 100 includes the robot 1 and the control device 9 that controls the driving of the robot 1. The robot 1 includes a base 10, a first arm 11 connected to the base 10 and rotatable about a first rotation axis J1 relative to the base 10, a second arm 12 including an arm base 121 connected to the first arm 11 and rotatable about a second rotation axis J2 parallel to the first rotation axis J1 relative to the first arm 11, a spline shaft 133 disposed on the second arm 12 and extending along a third rotation axis J3 parallel to the first rotation axis J1, and a spline nut 131 and a ball screw nut 132 attached to the spline shaft 133. The working head 13 is configured to rotate the spline shaft 133 at least around the third rotation axis J3 when the ball screw nut 132 is rotated, and to move the spline shaft 133 linearly along the third rotation axis J3 when the ball screw nut 132 is rotated, and is also configured to rotate the spline shaft 133 linearly along the third rotation axis J3 when the ball screw nut 132 is rotated, and is configured to rotate the spline shaft first drive mechanism 23 at least around the third rotation axis J3 by rotating the spline nut 131, and to move the spline shaft 133 linearly along the third rotation axis J3 by rotating the ball screw nut 132. The spline shaft first drive mechanism 23 also has a first motor 231 fixed to the arm base 121, a first pulley 51 fixed to the rotating shaft of the first motor 231, a second pulley 52 fixed to the spline nut 131, an intermediate pulley 54 that rotates around a fourth rotating axis J4 parallel to the first rotating axis J1 relative to the arm base 121, a first belt 55 that is looped around the first pulley 51 and the intermediate pulley 54, and a second belt 56 that is looped around the intermediate pulley 54 and the second pulley 52. The spline shaft second drive mechanism 24 also has a second motor 241 fixed to the arm base 121, a third pulley 242a fixed to the rotation shaft of the second motor 241, a fourth pulley 242b fixed to the ball screw nut 132, and a third belt 242c passed around the third pulley 242a and the fourth pulley 242b.In addition, when a line intersecting the second rotation axis J2 and the third rotation axis J3 is defined as an imaginary center axis A of the second arm 12 in a plan view along the second rotation axis J2, the first motor 231 and the intermediate pulley 54 are located on one side of the imaginary center axis A, and the second motor 241 is located on the other side. Furthermore, the arm base 121 is formed with a through-hole 121a penetrating the arm base 121 in a direction along the second rotation axis J2. The through-hole 121a is biased toward one side of the imaginary center axis A, i.e., toward the side where the intermediate pulley 54 is located, in a plan view along the second rotation axis J2. With this configuration, at least a portion of the weight increase due to the intermediate pulley 54 on one side of the imaginary center axis A can be canceled out by the weight reduction due to the through-hole 121a. Therefore, by forming the through-hole 121a, the weight balance of the second arm 12 can be improved. That is, it is possible to minimize the difference in weight between one side and the other side of the imaginary central axis A. As a result, the driving accuracy of the second arm 12 is improved.

[0073] Second Embodiment FIG. 10 is a top view showing the inside of the second arm of the robot according to the second embodiment.

[0074] The robot 1 according to this embodiment is similar to the robot 1 according to the first embodiment, except for the placement of the mounting member 16. In the following description, differences between the robot 1 according to this embodiment and the first embodiment will be mainly described, and descriptions of similar points will be omitted. In addition, in the drawings of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0075] As shown in FIG. 10 , in the robot 1 of this embodiment, the mounting member 16 is positioned offset to the other side of the imaginary central axis A, i.e., the side opposite the intermediate pulley 54, in a plan view along the second rotation axis J2. Note that "the mounting member 16 is positioned offset to the other side of the imaginary central axis A" means that the center of gravity of the mounting member 16, including the inertial sensor module 6 and the spacer, is positioned on the other side of the imaginary central axis A in a plan view along the second rotation axis J2. Therefore, as long as the above-described positional relationship is satisfied, the entire mounting member 16 may be positioned on the other side of the imaginary central axis A, or may be positioned across both sides of the imaginary central axis A. With this configuration, a portion of the weight increase on one side of the imaginary central axis A due to the intermediate pulley 54 can be canceled out by the weight increase on the other side of the imaginary central axis A due to the mounting member 16. Therefore, the through hole 121a can be smaller than in the first embodiment, making it easier to form the through hole 121a.

[0076] As described above, the robot 1 of this embodiment is disposed on the second arm 12 and includes the mounting member 16 on which the inertial sensor module 6 for measuring the inertia of the second arm 12 is mounted. The mounting member 16 is positioned offset to the other side of the imaginary central axis A, that is, the side opposite the intermediate pulley 54, in a plan view taken along the second rotation axis J2. With this configuration, a portion of the increase in weight on one side of the imaginary central axis A due to the intermediate pulley 54 can be canceled out by the increase in weight on the other side of the imaginary central axis A due to the mounting member 16. Therefore, compared to the first embodiment described above, the through hole 121a can be smaller, making it easier to form the through hole 121a.

[0077] The second embodiment can also achieve the same effects as the first embodiment described above.

[0078] While the robot and robot system of the present invention have been described above based on the illustrated embodiments, the present invention is not limited thereto, and the configuration of each component can be replaced with any configuration having a similar function. Furthermore, any other configuration may be added to the present invention. For example, in the above-described embodiment, the robot 1 includes the duct 14, but the duct 14 may be omitted. In this case, the wiring 31 is routed through the first arm 11 to the base 10 and the second arm 12. Furthermore, in the above-described embodiment, the robot 1 is a floor-mounted SCARA robot in which the base 10 is fixed to the floor or the like. However, the robot 1 may also be a ceiling-suspended SCARA robot in which the base 10 is suspended from the ceiling. In this case, the base 10 is suspended from a top plate located at the top of a stand having frame-shaped legs, for example. [Explanation of symbols]

[0079] 1...robot, 10...base, 100...robot system, 11...first arm, 12...second arm, 121...arm base, 121a...through hole, 122...frame, 123...cover, 123a...insertion hole, 123b...guide wall, 13...working head, 131...spline nut, 132...ball screw nut, 133...spline shaft, 14...duct, 141...base end opening, 142...tip opening, 16...mounting member, 17...brake release button, 181...connector, 182...connector, 21...first arm drive mechanism, 211...reduction gear, 211a...circular spline, 211b...flexspline, 211c...wave generator, 212...motor, 22...second arm drive mechanism, 221...reduction gear, 221a...circular spline, 221b...flexspline, 221c...wave generator, 222...motor, 23...spline shaft first drive mechanism, 231...first motor, 232...reduction gear, 232a...first reduction gear, 232b...second reduction gear , 24...Spline shaft second drive mechanism, 241...Second motor, 242...Reduction mechanism, 242a...Third pulley, 242b...Fourth pulley, 242c...Third belt, 243...Brake, 243a...Plate, 243b...Plate, 31...Wiring, 32...Wiring, 33...Wiring, 41...Support member, 42...Support member, 501...Bearing, 502...Bearing, 51...First pulley, 52...Second pulley, 54...Intermediate pulley, 541...First intermediate pulley, 541a...Belt mounting portion, 541 b...connecting portion, 541c...thinning portion, 542...second intermediate pulley, 543...shaft portion, 55...first belt, 56...second belt, 59...support member, 591...first holding portion, 592...second holding portion, 593...connecting portion, 6...inertial sensor module, 61...substrate, 62...angular velocity sensor, 8...brake control substrate, 82...light emitting element, 85...lens, 9...control device, 91...control substrate, 92...power supply substrate, A...virtual center axis, J1...first rotating shaft, J2...second rotating shaft, J3...third rotating shaft, J4...fourth rotating shaft, L...light

Claims

1. The base and a first arm connected to the base and rotatable about a first rotation axis relative to the base; a second arm including an arm base connected to the first arm and rotating relative to the first arm about a second rotation axis parallel to the first rotation axis; a working head that is disposed on the second arm and includes a spline shaft that extends along a third rotation axis parallel to the first rotation axis, and a spline nut and a ball screw nut that are attached to the spline shaft, wherein the spline shaft rotates about the third rotation axis when the spline nut is rotated, and the spline shaft moves linearly along the third rotation axis when the ball screw nut is rotated; a first spline shaft drive mechanism that is disposed within the second arm and that rotates the spline nut to rotate the spline shaft about the third rotation axis, and a second spline shaft drive mechanism that rotates the ball screw nut to linearly move the spline shaft along the third rotation axis, the first spline shaft drive mechanism includes a first motor fixed to the arm base, a first pulley fixed to a rotation shaft of the first motor, a second pulley fixed to the spline nut, an intermediate pulley that rotates around a fourth rotation shaft parallel to the first rotation shaft with respect to the arm base, a first belt that is wound around the first pulley and the intermediate pulley, and a second belt that is wound around the intermediate pulley and the second pulley, the second spline shaft drive mechanism includes a second motor fixed to the arm base, a third pulley fixed to a rotation shaft of the second motor, a fourth pulley fixed to the ball screw nut, and a third belt looped around the third pulley and the fourth pulley, when a straight line intersecting the second rotation axis and the third rotation axis is defined as an imaginary center axis of the second arm in a plan view from a direction along the second rotation axis, the first motor and the intermediate pulley are located on one side of the imaginary center axis, and the second motor is located on the other side of the imaginary center axis, a through hole is formed in the arm base, penetrating the arm base in a direction along the second rotation axis, and the through hole is positioned biased to one side of the virtual central axis when viewed in a plan view from the direction along the second rotation axis.

2. the third rotation shaft is located closer to the tip end of the second arm than the fourth rotation shaft, The robot according to claim 1 , wherein the through hole is located closer to the third rotation axis than the fourth rotation axis in a plan view along the second rotation axis.

3. The robot according to claim 1 , wherein the through hole and the intermediate pulley overlap in a plan view along the second rotation axis.

4. The robot according to claim 1 , wherein the intermediate pulley and the third belt overlap each other in a plan view along the second rotation shaft.

5. The robot according to claim 1 , wherein the intermediate pulley and the virtual central axis overlap in a plan view along the second rotation axis.

6. the intermediate pulley has a shaft portion extending along the fourth rotation shaft, a first intermediate pulley that is disposed on the shaft portion and around which the first belt is wound, and a second intermediate pulley that is disposed on the shaft portion, is positioned closer to the arm base than the first intermediate pulley, and around which the second belt is wound, 2. The robot according to claim 1, further comprising a support member fixed to the arm base, which supports a portion of the shaft between the first intermediate pulley and the second intermediate pulley via a first bearing, and which supports a portion of the shaft on the arm base side of the second intermediate pulley via a second bearing.

7. The robot according to claim 6 , wherein the third belt is located between the first belt and the second belt in a plan view from a direction perpendicular to the fourth rotation axis.

8. the first intermediate pulley has a larger diameter than the second intermediate pulley; The robot according to claim 6 , wherein the first intermediate pulley has a lightening portion formed therein that penetrates the first intermediate pulley in a direction along the fourth rotation shaft.

9. a mounting member disposed on the second arm and on which an inertial sensor module for measuring the inertia of the second arm is mounted; The robot according to claim 1 , wherein the placement member overlaps with the imaginary central axis in a plan view from a direction along the second rotation axis.

10. an inertial sensor module disposed on the second arm and configured to measure the inertia of the second arm; The robot according to claim 1 , wherein the inertial sensor module is positioned offset toward the other side of the virtual central axis in a plan view along the second rotation axis.

11. the third rotation shaft is located closer to the tip end of the second arm than the fourth rotation shaft, the through hole is located closer to the third rotation axis than the fourth rotation axis in a plan view from a direction along the second rotation axis, When viewed from a plane in a direction along the second rotation shaft, the through hole and the intermediate pulley overlap, the intermediate pulley and the third belt overlap, and the intermediate pulley and the virtual central axis overlap, the intermediate pulley includes a first intermediate pulley around which the first belt is wound, and a second intermediate pulley arranged next to the first intermediate pulley in a direction along the fourth rotation shaft and around which the second belt is wound, the third belt is located between the first belt and the second belt in a plan view from a direction perpendicular to the fourth rotation shaft, the first intermediate pulley has a larger diameter than the second intermediate pulley, and the first intermediate pulley has a lightening portion formed therein that penetrates the first intermediate pulley in a direction along the fourth rotation shaft; 2. The robot according to claim 1, further comprising an inertial sensor module disposed on the second arm, the inertial sensor module being positioned to overlap with the virtual central axis or to be offset to the other side of the virtual central axis in a planar view from a direction along the second rotation axis, and measuring the inertia of the second arm.

12. Robots and a control device that controls the driving of the robot, The robot includes a base and a first arm connected to the base and rotatable about a first rotation axis relative to the base; a second arm including an arm base connected to the first arm and rotating relative to the first arm about a second rotation axis parallel to the first rotation axis; a working head that is disposed on the second arm and includes a spline shaft that extends along a third rotation axis parallel to the first rotation axis, and a spline nut and a ball screw nut that are attached to the spline shaft, wherein the spline shaft rotates about the third rotation axis when the spline nut is rotated, and the spline shaft moves linearly along the third rotation axis when the ball screw nut is rotated; a first spline shaft drive mechanism that is disposed within the second arm and that rotates the spline nut to rotate the spline shaft about the third rotation axis, and a second spline shaft drive mechanism that rotates the ball screw nut to linearly move the spline shaft along the third rotation axis, the first spline shaft drive mechanism includes a first motor fixed to the arm base, a first pulley fixed to a rotation shaft of the first motor, a second pulley fixed to the spline nut, an intermediate pulley that rotates around a fourth rotation shaft parallel to the first rotation shaft with respect to the arm base, a first belt that is wound around the first pulley and the intermediate pulley, and a second belt that is wound around the intermediate pulley and the second pulley, the second spline shaft drive mechanism includes a second motor fixed to the arm base, a third pulley fixed to a rotation shaft of the second motor, a fourth pulley fixed to the ball screw nut, and a third belt looped around the third pulley and the fourth pulley, when a straight line intersecting the second rotation axis and the third rotation axis is defined as an imaginary center axis of the second arm in a plan view from a direction along the second rotation axis, the first motor and the intermediate pulley are located on one side of the imaginary center axis, and the second motor is located on the other side of the imaginary center axis, a through hole is formed in the arm base, penetrating the arm base in a direction along the second rotation axis, and the through hole is positioned biased to one side of the virtual central axis when viewed in a plan view from the direction along the second rotation axis.

Images