Robot and robot system

Abstract

The invention provides a robot and a robot system. The robot has a second arm with excellent weight balance. When a straight line intersecting with the second rotating shaft and the third rotating shaft is set as an imaginary central shaft of the second arm in a plan view along the direction of the second rotating shaft, the first motor and the middle pulley are located on one side of the imaginary central shaft, and the second motor is located on the other side of the imaginary central shaft. A through hole penetrating through the arm base in a direction along the second rotation axis is formed in the arm base, and the through hole is disposed so as to be biased toward the imaginary central axis when viewed in plan from the direction along the second rotation axis.

Description

Technical Field

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

[0002] The robot described in Patent Document 1 is a SCARA robot comprising: a base; a first arm rotatably connected to the base about a first rotation axis extending in the vertical direction; a second arm rotatably connected to the first arm about a second rotation axis extending in the vertical direction; and a work head disposed on the second arm. Furthermore, the work head comprises a spline nut and a ball screw nut arranged coaxially in the vertical direction, and a spline shaft inserted through the spline nut and the ball screw nut. In this work head, rotating the spline nut causes the spline shaft to rotate about a third rotation axis extending in the vertical direction and to move linearly along the third rotation axis. Rotating the ball screw nut causes the spline shaft to move linearly along the third rotation axis.

[0003] The robot also includes a first spline shaft drive mechanism that rotates the spline nut and the spline shaft about a third rotation axis. The first spline shaft drive mechanism includes a first motor; a drive pulley fixed to the first motor's rotation shaft; 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 extending in a vertical direction; a first belt looped around the drive pulley and the intermediate pulley; and a second belt looped around the intermediate pulley and the driven pulley.

[0004] The robot also includes a second spline shaft drive mechanism that rotates the ball screw nut and linearly moves the spline shaft along a third rotational axis. The second spline shaft drive mechanism includes a second motor; a drive pulley fixed to the rotational shaft of the second motor; a driven pulley fixed to the ball screw nut; and a belt looped around the drive pulley and the driven pulley.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-079111

[0006] However, when viewed from above in the direction along the second rotation axis, when a straight line intersecting the second rotation axis and the third rotation axis is set as the imaginary center axis of the second arm, in the robot of patent document 1, the intermediate pulley included only in the first drive mechanism of the spline shaft is arranged to be biased to one side of the imaginary center axis. Therefore, due to the weight of the intermediate pulley, the difference between the weight on one side and the weight on the other side relative to the imaginary center axis becomes larger, and there is a possibility that the driving accuracy of the second arm will be reduced. Summary of the Invention

[0007] The robot of the present invention has:

[0008] abutment;

[0009] a first arm connected to the base and rotating relative to the base around a first rotation axis;

[0010] a second arm having an arm base connected to the first arm, the second arm being rotatable relative to the first arm about a second rotation axis parallel to the first rotation axis;

[0011] a working head disposed on the second arm, the working head comprising a spline shaft along a third rotation axis parallel to the first rotation axis, and a spline nut and a ball screw nut mounted on the spline shaft, wherein when the spline nut is rotated, the spline shaft rotates about the third rotation axis, and when the ball screw nut is rotated, the spline shaft moves linearly along the third rotation axis; and

[0012] A first spline shaft drive mechanism and a second spline shaft drive mechanism are arranged in the second arm. The first spline shaft drive mechanism rotates the spline nut to rotate the spline shaft around the third rotation axis, and the second spline shaft drive mechanism rotates the ball screw nut to linearly move the spline shaft along the third rotation axis.

[0013] The first spline shaft drive mechanism includes: a first motor fixed to the arm base; a first pulley fixed to the rotating shaft of the first motor; a second pulley fixed to the spline nut; an intermediate pulley rotating around a fourth rotating shaft parallel to the first rotating shaft relative to the arm base; a first belt hung around the first pulley and the intermediate pulley; and a second belt hung around the intermediate pulley and the second pulley.

[0014] The second spline shaft drive mechanism includes: a second motor fixed to the arm base; a third pulley fixed to the rotating shaft of the second motor; a fourth pulley fixed to the ball screw nut; and a third belt hung around the third pulley and the fourth pulley.

[0015] When viewed from above along the second rotation axis, and when a straight line intersecting the second rotation axis and the third rotation axis is set as an imaginary central axis of the second arm, the first motor and the intermediate pulley are located on one side of the imaginary central axis, and the second motor is located on the other side of the imaginary central axis.

[0016] A through hole is formed in the arm base and passes through the arm base in a direction along the second rotation axis. The through hole is arranged offset to the one side of the imaginary central axis when viewed from above in the direction along the second rotation axis.

[0017] The robot system of the present invention has:

[0018] Robots; and

[0019] A control device controls the driving of the robot,

[0020] The robot has:

[0021] abutment;

[0022] a first arm connected to the base and rotating relative to the base around a first rotation axis;

[0023] a second arm having an arm base connected to the first arm, the second arm being rotatable relative to the first arm about a second rotation axis parallel to the first rotation axis;

[0024] a working head disposed on the second arm, the working head comprising a spline shaft along a third rotation axis parallel to the first rotation axis, and a spline nut and a ball screw nut mounted on the spline shaft, wherein when the spline nut is rotated, the spline shaft rotates about the third rotation axis, and when the ball screw nut is rotated, the spline shaft moves linearly along the third rotation axis; and

[0025] A first spline shaft drive mechanism and a second spline shaft drive mechanism are arranged in the second arm. The first spline shaft drive mechanism rotates the spline nut to rotate the spline shaft around the third rotation axis, and the second spline shaft drive mechanism rotates the ball screw nut to linearly move the spline shaft along the third rotation axis.

[0026] The first spline shaft drive mechanism includes: a first motor fixed to the arm base; a first pulley fixed to the rotating shaft of the first motor; a second pulley fixed to the spline nut; an intermediate pulley rotating around a fourth rotating shaft parallel to the first rotating shaft relative to the arm base; a first belt hung around the first pulley and the intermediate pulley; and a second belt hung around the intermediate pulley and the second pulley.

[0027] The second spline shaft drive mechanism includes: a second motor fixed to the arm base; a third pulley fixed to the rotating shaft of the second motor; a fourth pulley fixed to the ball screw nut; and a third belt hung around the third pulley and the fourth pulley.

[0028] When viewed from above along the second rotation axis, and when a straight line intersecting the second rotation axis and the third rotation axis is set as an imaginary central axis of the second arm, the first motor and the intermediate pulley are located on one side of the imaginary central axis, and the second motor is located on the other side of the imaginary central axis.

[0029] A through hole is formed in the arm base and passes through the arm base in a direction along the second rotation axis. The through hole is arranged offset to the one side of the imaginary central axis when viewed from above in the direction along the second rotation axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a side view showing the robot according to the first embodiment.

[0031] Figure 2 It is a cross-sectional view showing the connection portion between the base and the first arm.

[0032] Figure 3 This is a cross-sectional view of the second arm as viewed from one lateral side.

[0033] Figure 4 This is a cross-sectional view of the second arm as viewed from the other side.

[0034] Figure 5 It is a perspective view showing an enlarged front end portion of the frame.

[0035] Figure 6 It is a top view showing the interior of the second arm.

[0036] Figure 7 It is a cross-sectional view showing an enlarged intermediate pulley.

[0037] Figure 8 It is a cross-sectional view showing an enlarged front end portion of the frame.

[0038] Figure 9 It is a plan view for explaining the arrangement of through holes formed in the arm base.

[0039] Figure 10 It is a plan view showing the interior of a second arm included in the robot according to the second embodiment.

[0040] Description of Reference Numerals

[0041] 1...Robot, 10...Base, 100...Robot system, 11...First arm, 12...Second arm, 121...Arm base, 121a...Through hole, 122...Frame, 123...Lid, 123a...Through hole, 123b...Guide wall, 13...Work head, 131...Spline nut, 132...Ball screw nut, 133...Spline shaft, 14...Pipe, 141...Base end opening, 142...Front end opening, 16...Placing member, 17...Brake release button, 181...Connector, 182...Connector, 2 1…First arm drive mechanism, 211…Reducer, 211a…Rigid pulley, 211b…Flexible pulley, 211c…Wave generator, 212…Motor, 22…Second arm drive mechanism, 221…Reducer, 221a…Rigid pulley, 221b…Flexible pulley, 221c…Wave generator, 222…Motor, 23…First spline shaft drive mechanism, 231…First motor, 232…Reducer, 232a…First reduction mechanism, 232b…Second reduction mechanism, 24…Second spline shaft drive mechanism, 241…Second motor, 242…Deceleration mechanism, 242a…Third pulley, 242b…Fourth pulley, 242c…Third belt, 243…Brake, 243a…Plate, 243b…Plate, 31…Wiring, 32…Wiring, 33…Wiring, 41…Supporting member, 42…Supporting member, 501…Bearing, 502…Bearing, 51…First pulley, 52…Second pulley, 54…Intermediate pulley, 541…First intermediate pulley, 541a…Belt mounting portion, 541b…Connecting portion, 541c…Weight reduction portion, 542…Second intermediate pulley Wheel, 543…Shaft, 55…First belt, 56…Second belt, 59…Supporting 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…Imaginary center axis, J1…First rotation axis, J2…Second rotation axis, J3…Third rotation axis, J4…Fourth rotation axis, L…Light. DETAILED DESCRIPTION

[0042] Hereinafter, the robot and the robot system of the present invention will be described in detail based on the embodiments shown in the drawings.

[0043] First embodiment

[0044] Figure 1 This is a side view showing the robot according to the first embodiment. Figure 2 It is a cross-sectional view showing the connection portion between the base and the first arm. Figure 3 This is a cross-sectional view of the second arm as viewed from one lateral side. Figure 4 This is a cross-sectional view of the second arm as viewed from the other side. Figure 5It is a perspective view showing an enlarged front end portion of the frame. Figure 6 It is a top view showing the interior of the second arm. Figure 7 It is a cross-sectional view showing an enlarged intermediate pulley. Figure 8 It is a cross-sectional view showing an enlarged front end portion of the frame. Figure 9 It is a plan view for explaining the arrangement of through holes formed in the arm base.

[0045] It should be noted that Figure 1 The up and down directions in the image are consistent with the vertical direction. Figure 1 The upper side is referred to as "upper" and the lower side is referred to as "lower." Furthermore, in this specification, "vertical" refers not only to being aligned with the vertical but also to being inclined relative to the vertical within a range that allows the effects of the present invention to be exerted, for example, being inclined within ±5° relative to the vertical. Similarly, in this specification, "parallel" refers not only to being aligned with the vertical but also to being inclined relative to the vertical within a range that allows the effects of the present invention to be exerted, for example, being inclined within ±5° relative to the vertical.

[0046] Figure 1 The robot system 100 shown includes a robot 1 and a control device 9 that controls the driving of the robot 1 .

[0047] Control device 9

[0048] like Figure 1 As shown, the control device 9 includes, for example, a control substrate 91 and a power substrate 92. However, the present invention is not limited thereto, and the control substrate 91 and the power substrate 92 may be formed as a single substrate.

[0049] The control board 91 generally controls the driving of various components of the robot 1. It includes a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory). The CPU reads and executes programs and data stored in the ROM, achieving the aforementioned functions. Furthermore, the control board 91 is electrically connected to a host computer (not shown) and controls the driving of various components of the robot 1 based on commands from the host computer. However, this is not limiting; the circuitry of the control board 91 and other components may be divided across multiple boards.

[0050] The power board 92 supplies power to the control board 91. The power board 92 includes a conversion circuit that converts externally supplied power to a predetermined value and supplies it to the control board 91. While the conversion circuit varies depending on the configuration of the robot 1, examples include an AC / DC conversion circuit that converts an alternating current (AC) signal to a direct current (DC) signal, and a step-up or step-down circuit that converts the voltage level of a signal. However, this is not limiting; the circuitry of the power board 92 and other components may be divided across multiple boards.

[0051] 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 located within the base 10 of the robot 1. However, the placement of the control device 9 is not particularly limited. For example, the control device 9 may be located outside the base 10. In this case, the robot 1 and the control device 9 may be connected via a cable or wirelessly.

[0052] Robot 1

[0053] Robot 1 is a horizontal multi-joint robot (SCARA robot). Figure 1 As shown, the robot 1 includes: a base 10 fixed to the ground, etc.; a first arm 11 rotatably connected to the base 10; a second arm 12 rotatably connected to the first arm 11; an operating head 13 arranged on the second arm 12; and a pipe 14 connecting the base 10 and the second arm 12.

[0054] like Figure 2 As shown, the first arm 11 is connected to the base 10 at its base end portion and rotates relative to the base 10 around a first rotation axis J1 along the vertical direction.

[0055] like Figure 3 and Figure 4 As shown, the second arm 12 is connected to the first arm 11 at its base end and rotates relative to the first arm 11 about a second rotation axis J2 that is parallel to the first rotation axis J1. Furthermore, the second arm 12 includes 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.

[0056] Furthermore, the frame 122 is a cantilever beam, the base end of which is fixed to the arm base 121, and the front end of which is a free end separated from the arm base 121. Such a frame 122 is connected to the pipe 14. In addition, a connector 181 and a brake release button 17 for releasing the brake 243 described later are arranged on the frame 122. The connector 181 and the brake release button 17 are not covered by the cover 123, but are exposed to the outside of the second arm 12. Figure 1 As shown, a connector 182 is arranged on the back surface of the base 10 , forming a pair with the connector 181 , and the connectors 181 and 182 are connected to each other via a wiring 31 .

[0057] Furthermore, a lens 85 that emits light 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.

[0058] In addition, if Figure 6 As shown, the front end of frame 122 is supported on arm base 121 via a pair of support members 41, 42. As previously mentioned, frame 122 is a cantilever beam, and therefore the front end is susceptible to vertical deflection. Consequently, frame 122 may be plastically deformed by stresses applied, for example, when a user inserts a connector into connector 181, presses brake release button 17, or installs wiring or devices connected to connector 181 on frame 122. Therefore, by supporting the front end of frame 122 with a pair of support members 41, 42, deformation of frame 122 can be effectively suppressed.

[0059] like Figure 1 As shown, the pipe 14 is a tubular component arranged outside the first arm 11, and directly connects the base 10 and the second arm 12 without passing through the first arm 11. Figures 2 to 4 As shown, the base end of the duct 14 is connected to the base 10, and the front end is connected to the second arm 12. The duct 14 has a base end opening 141 facing the interior of the base 10 and a front end opening 142 facing the interior of the second arm 12. Thus, the base 10 and the second arm 12 are connected via the duct 14. Furthermore, a plurality of wires 31 are routed through the duct 14 to the base 10 and the second arm 12. As with the aforementioned connectors 181 and 182, these wires 31 electrically connect the electronic components disposed in the second arm 12 to the electronic components disposed in the base 10. Furthermore, the wires 31 are routed, for example, through the gap between the motors 231 and 241 and are routed further toward the front end of the motors 231 and 241.

[0060] like Figure 3 and Figure 4As shown, the working head 13 is disposed at the front end of the second arm 12. Furthermore, the working head 13 includes a spline nut 131 and a ball screw nut 132, which are arranged coaxially and vertically aligned, and a spline shaft 133 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 its central axis, a third rotation axis J3 that is parallel to the first rotation axis J1, and moves linearly (lifts and lowers) 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. 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 corresponding to the work is attached to the lower end of the spline shaft 133.

[0061] In addition, if Figure 2 and Figure 3 As shown, the robot 1 includes a first arm driving mechanism 21 for rotating the first arm 11 relative to the base 10 around the first rotation axis J1 , and a second arm driving mechanism 22 for rotating the second arm 12 relative to the first arm 11 around the second rotation axis J2 .

[0062] like Figure 2 As shown, the first arm drive mechanism 21 has a speed reducer 211 that rotatably connects the base 10 and the first arm 11, and a motor 212 with a built-in encoder disposed within the base 10. The motor 212 is a servo motor, specifically a three-phase motor driven by three-phase AC, and is fixed to the base 10. The speed reducer 211 is a wave gear device, with a rigid pulley 211a fixed to the base 10 and a flexible pulley 211b fixed to the first arm 11. In addition, the rotation shaft of the motor 212 is fixed to the wave generator 211c. Therefore, the wave generator 211c rotates together with the rotation of the motor 212, and the flexible pulley 211b rotates at a predetermined speed reduction ratio relative to the rotation of the wave generator 211c. As a result, the first arm 11 rotates about the first rotation axis J1 relative to the base 10. However, the structure of the first arm drive mechanism 21 is not particularly limited.

[0063] The second arm driving mechanism 22 has the same structure as the first arm driving mechanism 21. Figure 3 and Figure 4As shown, the second arm drive mechanism 22 includes a speed reducer 221 that rotatably connects the first arm 11 and the second arm 12, and an encoder-built-in motor 222 disposed within the second arm 12. The motor 222 is a servo motor, specifically a three-phase motor driven by three-phase AC, and is fixed to the arm base 121. The speed reducer 221 is a wave gear device, with a rigid pulley 221a fixed to the arm base 121 and a flexible pulley 221b fixed to the first arm 11. Furthermore, the rotation shaft of the motor 222 is fixed to the wave generator 221c. Therefore, the wave generator 221c rotates in conjunction with the rotation of the motor 222, and the flexible pulley 221b rotates at a predetermined speed 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.

[0064] In addition, if Figure 3 、 Figure 4 and Figure 6 As shown, the robot 1 includes: a first spline shaft drive mechanism 23 that rotates the spline nut 131 and rotates and linearly moves the spline shaft 133; and a second spline shaft drive mechanism 24 that rotates the ball screw nut 132 and linearly moves the spline shaft 133.

[0065] like Figure 3 and Figure 6 As shown, the spline shaft first drive mechanism 23 includes a first motor 231 with a built-in encoder, which is disposed within 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, specifically a three-phase motor driven by three-phase AC, and is fixed to the arm base 121.

[0066] The reduction mechanism 232 includes: a first pulley 51, fixed to the rotating 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 by the support member 59 via bearings 501 and 502 described later, and rotates around a fourth rotating axis J4 in the vertical direction relative to the arm base 121; a first belt 55, hung around the first pulley 51 and the intermediate pulley 54; and a second belt 56, hung around the intermediate pulley 54 and the second pulley 52.

[0067] In addition, if Figure 7As shown, the intermediate pulley 54 includes a first intermediate pulley 541; a second intermediate pulley 542 located below the first intermediate pulley 541, i.e., on the arm base 121 side, and having a smaller diameter than the first intermediate pulley 541; and a shaft 543 disposed along the fourth rotation axis J4 and connecting the first intermediate pulley 541 and the second intermediate pulley 542. It should be noted that in this embodiment, the second intermediate pulley 542 and the shaft 543 are integrally formed, and the shaft 543 is fixed to the first intermediate pulley 541. However, this is not limiting. Alternatively, 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. Alternatively, the first intermediate pulley 541, the second intermediate pulley 542, and the shaft 543 may be separate components and fixed to each other.

[0068] The lower end of the shaft portion 543 protrudes below the second intermediate pulley 542. The intermediate pulley 54 is rotatably supported by the support member 59 at two locations on the shaft portion 543 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, while the bearing 502 is located below the second intermediate pulley 542.

[0069] The support member 59 includes a first retaining portion 591, which holds the portion of the shaft 543 between the first intermediate pulley 541 and the second intermediate pulley 542 via the bearing 501; a second retaining portion 592, which holds the portion of the shaft 543 below the second intermediate pulley 542 via the bearing 502; and a connecting portion 593, which connects the first retaining portion 591 and the second retaining portion 592. It should be noted that in this embodiment, the second retaining portion 592 and the connecting portion 593 are integrally formed, and the connecting portion 593 and the first retaining portion 591 are fixed by screws. However, this is not limiting. Alternatively, the first retaining portion 591 and the connecting portion 593 may be integrally formed, and the connecting portion 593 and the second retaining portion 592 may be fixed by screws. Alternatively, the first retaining portion 591, the second retaining portion 592, and the connecting portion 593 may be formed separately. Furthermore, the support member 59 and the arm base 121 may be fixed by screws. In this 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 the through holes may be fastened to the arm base 121. This facilitates the fixing operation of the support member 59 and the arm base 121.

[0070] Furthermore, the first intermediate pulley 541 is aligned with the first pulley 51 and is arranged at the same height. Furthermore, the first intermediate pulley 541 has a larger diameter than the first pulley 51, and the first belt 55 is wound around the first pulley 51 and the first intermediate pulley 541. Furthermore, the first pulley 51, the first intermediate pulley 541, and the first belt 55 constitute the first reduction mechanism 232a at the front end. Meanwhile, the second intermediate pulley 542 is aligned with the second pulley 52 and is arranged at the same height. Furthermore, the second intermediate pulley 542 has a smaller diameter than the second pulley 52, and the second belt 56 is wound around the second intermediate pulley 542 and the second pulley 52. ​​Furthermore, the second intermediate pulley 542, the second pulley 52, and the second belt 56 constitute the second reduction mechanism 232b at the rear end.

[0071] In such a 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, and the first intermediate pulley 541 and the second intermediate pulley 542 rotate integrally around the fourth rotation axis J4. In addition, the rotation of the second intermediate pulley 542 is transmitted to the second pulley 52 via the second belt 56, and the second pulley 52 and the spline nut 131 rotate integrally 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, since the reduction mechanism 232 includes the first reduction mechanism 232a and the second reduction mechanism 232b, it is possible to reduce the rotation of the first motor 231 in two stages, and the spline nut 131 can be rotated with a greater torque.

[0072] Here, as Figure 7 As shown, 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 and the belt mounting portion 541a. Furthermore, the connecting portion 541b is thin-walled, and its thickness, i.e., its length along the fourth rotation axis J4, is smaller than that of the belt mounting portion 541a. This allows for a lighter weight of the intermediate pulley 54. Furthermore, a weight-reducing portion 541c, comprising a through-hole extending through the thickness, is formed in the connecting portion 541b. This further reduces the weight of the intermediate pulley 54. In particular, the first intermediate pulley 541 has a larger diameter than the second intermediate pulley 542. Therefore, the thinning of the connecting portion 541b and the formation of the weight-reducing portion 541c significantly reduce the weight of the intermediate pulley 54.

[0073] Furthermore, when viewed from above along the fourth rotation axis J4, the lightening portion 541c overlaps with the screws securing the connecting portion 593 and the first retaining portion 591. Therefore, a tool such as a screwdriver can be inserted through the lightening portion 541c to tighten the screws, making it easy to secure the connecting portion 593 and the first retaining portion 591.

[0074] It should be noted that in this embodiment, the two fan-shaped weight-reducing portions 541c are symmetrically arranged with respect to the fourth rotation axis J4. However, the shape and number of the weight-reducing portions 541c are not particularly limited. Alternatively, the second intermediate pulley 542 may be formed with a weight-reducing portion similar to that of the first intermediate pulley 541. This further reduces the weight of the intermediate pulley 54. Furthermore, the weight-reducing portions 541c may be omitted.

[0075] like Figure 4 and Figure 6 As shown, the spline shaft second drive mechanism 24 includes a second motor 241 with a built-in encoder, which is disposed in 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, specifically a three-phase motor driven by three-phase AC, and is fixed to the arm base 121.

[0076] The reduction mechanism 242 includes a third pulley 242a fixed to the rotating shaft of the second motor 241, a fourth pulley 242b fixed to the ball screw nut 132, and a third belt 242c hung around the third pulley 242a and the fourth pulley 242b. In such a 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, and the fourth pulley 242b and the ball screw nut 132 rotate integrally around the third rotation axis J3. As a result, the spline shaft 133 moves linearly along the third rotation axis J3. In this way, by using the reduction mechanism 242, the rotation of the second motor 241 can be decelerated, and the ball screw nut 132 can be rotated with a sufficiently large torque.

[0077] It should be noted that if Figure 3 As shown, when viewed from above from a direction perpendicular to the fourth rotation axis J4, the third belt 242c is located between the first belt 55 and the second belt 56. That is, the first belt 55 is located on the upper side of the third belt 242c, and the second belt 56 is located on the lower side of the third belt 242c. According to such a structure, when viewed from above from the direction along the second rotation axis J2, the third belt 242c can be made to intersect with the first and second belts 55 and 56. Therefore, the configuration freedom of the intermediate pulley 54 is increased. However, the structure of the spline shaft second drive mechanism 24 is not particularly limited. For example, the third belt 242c can also be located on the upper side of the first belt 55, that is, located higher than the intermediate pulley 54.

[0078] like Figure 4As shown, brake 243 is an electromagnetic brake mounted on second motor 241 and comprises a pair of opposing plates 243a and 243b. One plate 243a is fixed to second motor 241, while the other plate 243b is fixed to the rotating shaft of second motor 241 and rotates with the shaft. Furthermore, by switching the power on / off (ON / OFF) control, the brake switches between a braking state, where plates 243a and 243b come into contact and restrict the rotation of the rotating shaft, and a brake-released state, where plates 243a and 243b separate and allow the rotation of the rotating shaft. In particular, brake 243 in this embodiment is a non-excitation electromagnetic brake. When power is applied (ON), the brake is released, and when power is removed (OFF), the brake is engaged. However, the configuration of brake 243 is not particularly limited.

[0079] In addition, if Figure 5 and Figure 8 As shown, the brake control board 8, which 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. Furthermore, the brake control board 8 is electrically connected to the brake 243 via wiring 32 and to the brake release button 17 via wiring 33. The brake control board 8 controls the actuation of the brake 243 based on commands from the control board 91, switching between the braking state and the brake release state. Furthermore, the brake control board 8 controls the actuation of the brake 243 based on operation of the brake release button 17, switching between the braking state and the brake release state.

[0080] In addition, if Figure 8 As shown, the robot 1 includes 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 before entering the lens 85. This causes the lens 85 to emit light. Therefore, by controlling the drive of the light-emitting element 82, the lens 85 can be switched between on / off, flashing, and off, or its light color, allowing the user to be notified of various information through the lens 85.

[0081] While power is being supplied to the motors 212, 222, 231, and 241, that is, 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, causing the lens 85 to illuminate. This state will be referred to below as the first illuminating state. This makes it easy to notify the user that the robot 1 is powered on. Furthermore, when the brake release button 17 is pressed, and the brake 243 is in the released state, the brake control board 8 emits light L of a different color from the first illuminating state from the light-emitting element 82, causing the lens 85 to illuminate. This state will be referred to below as the second illuminating state. This makes it easy to notify the user that the brake 243 is in the released state. However, the notification method is not particularly limited; for example, the first illuminating state may be on, the second illuminating state may be off, or the first illuminating state may be on, the second illuminating state may be flashing.

[0082] 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.

[0083] In addition, if Figure 3 、 Figure 4 and Figure 6 As shown, the robot 1 includes a mounting member 16 disposed within the second arm 12 and mounting an inertial sensor module 6 for measuring the inertia of the second arm 12. 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.

[0084] The inertial sensor module 6 includes a substrate 61 secured to the mounting member 16 via a plurality of spacers 164, and an angular velocity sensor 62 mounted on the substrate 61 to detect the angular velocity of the second arm 12 about the vertical axis. The angular velocity sensor 62 includes a package, an angular velocity sensor element housed within the package, and circuit components. The angular velocity sensor element, for example, is a crystal oscillator and includes a driving arm that vibrates when a driving signal is applied, and a detecting arm that detects vibrations when the Coriolis force generated by the angular velocity is applied, outputting a signal corresponding to the magnitude of the detected force. Furthermore, the circuit components include, for example, a driving circuit that vibrates the driving arm of the crystal oscillator when a driving signal is applied, and a detecting circuit that detects angular velocity based on the signal output from the detecting arm. When viewed from above along the second rotational axis J2, the inertial sensor module 6 is positioned so as to overlap with the imaginary central axis A, described later. However, this is not limiting; the inertial sensor module 6 may also be positioned so as not to overlap with the imaginary central axis A.

[0085] Furthermore, a control circuit (not shown) is formed on substrate 61 to control the driving of angular velocity sensor 62 based on commands from control substrate 91. The control circuit includes a CPU (Central Processing Unit) and ROM (Read Only Memory). The CPU reads and executes programs and data stored in the ROM to achieve the functions described above.

[0086] 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. However, this is not limiting. For example, it may be an acceleration sensor that detects the acceleration of the second arm 12. Alternatively, it may be a composite sensor capable of detecting both angular velocity and acceleration. Furthermore, in this embodiment, the angular velocity sensor element is a crystal oscillator. However, this is not limiting. For example, it may be a silicon MEMS that detects angular velocity based on changes in the electrostatic capacitance between a movable electrode and a fixed electrode.

[0087] Here, as Figure 3 and Figure 4As shown, the cover 123 of the second arm 12 is formed with an insertion hole 123a for inserting the spline shaft 133. Furthermore, as the spline shaft 133 moves linearly up and down, airflow is generated between the insertion hole 123a and a through-hole 121a (described later) formed in the arm base 121. When this airflow strikes the inertial sensor module 6, the inertial sensor module 6 vibrates, potentially reducing the accuracy of angular velocity detection. Therefore, a guide wall 123b is formed between the spline shaft 133 of the cover 123 and the inertial sensor module 6 to guide the airflow. This makes it less likely that the airflow will strike the inertial sensor module 6, effectively suppressing a reduction in the accuracy of angular velocity detection by the inertial sensor module 6.

[0088] The above describes the overall structure of the robot 1. Next, the configuration of the various components included in the first spline shaft drive mechanism 23 and the second spline shaft drive mechanism 24 will be described. It should be noted that, hereinafter, when viewed from above along the second rotation axis J2, the straight line intersecting the second rotation axis J2 and the third rotation axis J3 will also be referred to as the imaginary center axis A of the second arm 12.

[0089] like Figure 9 As shown, when viewed from above along the second rotation axis J2, the first motor 231 and the intermediate pulley 54 of the spline shaft first drive mechanism 23 are positioned on one side of the imaginary central axis A, while the second motor 241 of the spline shaft second drive mechanism 24 is positioned on the other side of the imaginary central axis A. It should be noted that the phrase "the first motor 231 and the intermediate pulley 54 are positioned on one side of the imaginary central axis A" means that the central axis of the rotation shaft of the first motor 231 and the fourth rotation axis J4 are positioned on one side of the imaginary central axis A. Therefore, as long as the aforementioned positional relationship is satisfied, the first motor 231 and the intermediate pulley 54 can each be positioned entirely on one side of the imaginary central axis A or positioned so as to extend across both sides of the imaginary central axis A. Similarly, the phrase "the second motor 241 is positioned on the other side of the imaginary central axis A" means that the central axis of the rotation shaft of the second motor 241 is positioned on the other side of the imaginary central axis A. Therefore, as long as the above-mentioned 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 set to extend over both sides of the imaginary central axis A.

[0090] By arranging the first and second motors 231 and 241, which serve as weights, on opposite sides of the imaginary center axis A, the difference between the weight on one side of the imaginary center axis A and the weight on the other side can be minimized, for example, compared to a case where the first and second motors 231 and 241 are arranged on the same side of the imaginary center axis A. This can suppress deterioration in the weight balance of the second arm 12. However, in the first and second spline shaft drive mechanisms 23 and 24, only the intermediate pulley 54 included in the first spline shaft drive mechanism 23 is arranged on one side of the imaginary center axis A. This causes the weight on one side of the imaginary center axis A to increase, thereby deteriorating the weight balance of the second arm 12. Therefore, in the robot 1, a through hole 121a is formed in the arm base 121 to suppress deterioration in the weight balance caused by the intermediate pulley 54. The through hole 121a will be described in detail below.

[0091] like Figure 9 As shown, when viewed from above along the second rotation axis J2, the through-hole 121a is positioned offset toward one side of the imaginary central axis A. It should be noted that "the through-hole 121a is positioned offset toward 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 on one side of the imaginary central axis A is larger than the area on the other side. Therefore, as long as the above positional relationship is satisfied, the through-hole 121a can be positioned entirely toward one side of the imaginary central axis A or can be positioned on both sides of the imaginary central axis A. However, in this embodiment, the through-hole 121a is positioned entirely toward one side of the imaginary central axis A. By forming such a through-hole 121a, the weight reduction provided by the through-hole 121a on the side of the imaginary central axis A can offset at least a portion of the weight increase caused by the intermediate pulley 54. Therefore, the formation of the through-hole 121a effectively prevents deterioration in the weight balance of the second arm 12. 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.

[0092] Furthermore, when viewed from above 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, on the front end side of the second arm 12. With this configuration, the through hole 121a can reduce the weight of the front end portion of the second arm 12, thereby reducing the moment of inertia of the second arm 12.

[0093] Furthermore, when viewed from above along the second rotation axis J2, the through-hole 121a overlaps with the intermediate pulley 54. This configuration allows the intermediate pulley 54, which is the primary cause of weight balance degradation, and the through-hole 121a, which is used to improve weight balance, to be positioned closer together. Consequently, degradation of the weight balance of the second arm 12 can be effectively suppressed. However, this is not limiting; the through-hole 121a and the intermediate pulley 54 may also not overlap when viewed from above along the second rotation axis J2.

[0094] In addition, if Figure 9 As shown, the first intermediate pulley 541 is positioned above the third belt 242c. When viewed from above along the second rotation axis J2, the first intermediate pulley 541 overlaps the third belt 242c. This allows the intermediate pulley 54 to be positioned as close to the imaginary center axis A as possible when viewed from above along the second rotation axis J2, by overlapping the third belt 242c. Consequently, the deterioration of weight balance caused by the intermediate pulley 54 can be minimized, and the through-hole 121a required to improve weight balance can be correspondingly reduced. Since the size of the through-hole 121a that can be formed in the arm base 121 is limited, the through-hole 121a can be small, making it easier to create a through-hole 121a of a size that matches the deterioration of weight balance caused by the intermediate pulley 54. This effectively suppresses deterioration of weight balance in the second arm 12. Furthermore, the small size of the through-hole 121a can also prevent a reduction in the rigidity of the arm base 121. However, the present invention is not limited thereto, and the intermediate pulley 54 and the third belt 242 c may not overlap when viewed in plan from the direction along the second rotation axis J2 .

[0095] In addition, if Figure 9As shown, when viewed from above along the second rotation axis J2, the intermediate pulley 54 overlaps the imaginary center axis A. This configuration allows the intermediate pulley 54 to be positioned as close to the imaginary center axis A as possible. Consequently, the deterioration of weight balance caused by the intermediate pulley 54 can be minimized, and the through-hole 121a used to improve weight balance can be correspondingly reduced. Since the size of the through-hole 121a that can be formed in the arm base 121 is limited, the through-hole 121a can be relatively small, making it easier to form the through-hole 121a to a size that matches the deterioration of weight balance caused by the intermediate pulley 54. This effectively suppresses deterioration of weight balance in the second arm 12. Furthermore, since the through-hole 121a can be relatively small, a reduction in the rigidity of the arm base 121 can be minimized. In particular, as described above, in this embodiment, the third belt 242c is positioned between the first belt 55 and the second belt 56 when viewed from above in a direction perpendicular to the fourth rotation axis J4. Therefore, the third belt 242c can be arranged to intersect with the first and second belts 55 and 56. This increases the degree of freedom in the arrangement of the intermediate pulley 54, making it easier to position the intermediate pulley 54 closer to the imaginary central axis A. However, this is not limiting; the intermediate pulley 54 may also not overlap with the imaginary central axis A when viewed from above in a direction along the second rotation axis J2.

[0096] In this manner, in the robot 1, the intermediate pulley 54 is arranged so that it overlaps with the third belt 242c and the imaginary center axis A when viewed from above along the second rotation axis J2, thereby minimizing the deterioration in weight balance caused by the intermediate pulley 54. Furthermore, in this embodiment, as previously described, the intermediate pulley 54 is lightweighted by forming a weight-reducing portion 541c on the first intermediate pulley 541. Furthermore, the support member 59 supporting the intermediate pulley 54 is configured to support both the upper and lower sides of the second intermediate pulley 542, located on the lower side of the first and second intermediate pulleys 541 and 542, arranged vertically. This minimizes the center of gravity of the support member 59. These configurations minimize the deterioration in weight balance caused by the intermediate pulley 54. Thus, in the robot 1, not only the placement of the intermediate pulley 54 but also the lightweighting of the intermediate pulley 54 itself and the configuration of the support member 59 supporting the intermediate pulley 54 have been considered, thereby minimizing the deterioration in weight balance caused by the intermediate pulley 54.

[0097] In addition, if Figure 9 As shown, in the robot 1 , when viewed from above along the second rotation axis J2 , the placement member 16 overlaps the imaginary central axis A. This arrangement of the placement member 16 can suppress deterioration of the weight balance of the second arm 12 caused by the placement member 16 .

[0098] The robot system 100 has been described above. As mentioned above, the robot system 100 includes a robot 1 having: a base 10; a first arm 11 connected to the base 10 and rotating relative to the base 10 around a first rotation axis J1; a second arm 12 having an arm base 121 connected to the first arm 11, and rotating relative to the first arm 11 around a second rotation axis J2 parallel to the first rotation axis J1; a work head 13 arranged on the second arm 12, the work head 13 having a spline shaft 133 along a third rotation axis J3 parallel to the first rotation axis J1, and a spline nut 131 and a roller mounted on the spline shaft 133. The ball screw nut 132, when the spline nut 131 is rotated, the spline shaft 133 rotates at least around the third rotation axis J3, and when the ball screw nut 132 is rotated, the spline shaft 133 moves linearly along the third rotation axis J3; and the spline shaft first drive mechanism 23 and the spline shaft second drive mechanism 24 are arranged in the second arm 12, the spline shaft first drive mechanism 23 rotates the spline nut 131 and the spline shaft 133 rotates at least around the third rotation axis J3, and the spline shaft second drive mechanism 24 rotates the ball screw nut 132 and the spline shaft 133 moves linearly along the third rotation axis J3. The first spline shaft drive mechanism 23 includes a first motor 231 fixed to the arm base 121; a first pulley 51 fixed to the rotation axis of the first motor 231; a second pulley 52 fixed to the spline nut 131; an intermediate pulley 54 that rotates relative to the arm base 121 about a fourth rotation axis J4 parallel to the first rotation axis J1; a first belt 55 looped around the first pulley 51 and the intermediate pulley 54; and a second belt 56 looped around the intermediate pulley 54 and the second pulley 52. ​​The second spline shaft drive mechanism 24 includes a second motor 241 fixed to the arm base 121; a third pulley 242a fixed to the rotation axis of the second motor 241; a fourth pulley 242b fixed to the ball screw nut 132; and a third belt 242c looped around the third pulley 242a and the fourth pulley 242b. Furthermore, when viewed from above along the second rotation axis J2, with the line intersecting the second rotation axis J2 and the third rotation axis J3 as the imaginary central axis A of the second arm 12, the first motor 231 and the intermediate pulley 54 are located on one side of the imaginary central axis A, while the second motor 241 is located on the other side of the imaginary central axis A. Furthermore, a through-hole 121a is formed in the arm base 121, extending through the arm base 121 along the second rotation axis J2. The through-hole 121a is located on one side of the imaginary central axis A, that is, offset toward the side where the intermediate pulley 54 is located. With this configuration, the weight reduction provided by the through-hole 121a on the side of the imaginary central axis A offsets at least a portion of the increased weight of the intermediate pulley 54. Therefore, the formation of the through-hole 121a effectively prevents deterioration in the weight balance of the second arm 12.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.

[0099] Furthermore, as previously described, the third rotation axis J3 is located closer to the front end of the second arm 12 than the fourth rotation axis J4. When viewed from above 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. This configuration reduces the weight of the front end of the second arm 12 and reduces the moment of inertia of the second arm 12.

[0100] Furthermore, as previously described, when viewed from above along the second rotation axis J2, the through-hole 121a overlaps the intermediate pulley 54. This configuration allows the intermediate pulley 54, which is the primary cause of weight balance degradation, to be positioned closer to the through-hole 121a, which is used to improve weight balance. Consequently, degradation of the weight balance of the second arm 12 can be effectively suppressed.

[0101] Furthermore, as previously mentioned, when viewed from above along the second rotation axis J2, the intermediate pulley 54 overlaps the third belt 242c. This configuration allows the intermediate pulley 54 to be positioned as close as possible to the imaginary center axis A. Consequently, the deterioration in weight balance caused by the intermediate pulley 54 can be minimized, and the through-hole 121a used to achieve improved weight balance can be correspondingly reduced in size. Since the size of the through-hole 121a that can be formed in the arm base 121 is limited, the through-hole 121a can be relatively small, making it easier to form the through-hole 121a to a size that matches the deterioration in weight balance caused by the intermediate pulley 54. This effectively suppresses deterioration in weight balance of the second arm 12. Furthermore, the smaller through-hole 121a can prevent a reduction in the rigidity of the arm base 121.

[0102] Furthermore, as previously mentioned, when viewed from above along the second rotation axis J2, the intermediate pulley 54 overlaps the imaginary center axis A. This configuration allows the intermediate pulley 54 to be positioned as close to the imaginary center axis A as possible. Consequently, the deterioration in weight balance caused by the intermediate pulley 54 can be minimized, and the through-hole 121a required to achieve improved weight balance can be correspondingly reduced in size. Since the size of the through-hole 121a that can be formed in the arm base 121 is limited, the through-hole 121a can be relatively small, making it easier to form a through-hole 121a of a size appropriate for the deterioration in weight balance caused by the intermediate pulley 54. This effectively suppresses deterioration in weight balance of the second arm 12. Furthermore, since the through-hole 121a can be relatively small, a reduction in the rigidity of the arm base 121 can be minimized.

[0103] As previously described, 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 having the first belt 55 wound therearound; 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, having the second belt 56 wound therearound. Furthermore, the robot 1 includes a support member 59 fixed to the arm base 121. The support member 59 holds the portion of the shaft portion 543 between the first and second intermediate pulleys 541, 542, via a bearing 501 serving as a first bearing, and holds the portion of the shaft portion 543 closer to the arm base 121 than the second intermediate pulley 542, via a bearing 502 serving as a second bearing. This configuration of the support member 59 allows the center of gravity of the support member 59 to be kept low. Consequently, the deterioration of the weight balance caused by the intermediate pulley 54 can be minimized.

[0104] Furthermore, as previously described, when viewed from above in a direction perpendicular to the fourth rotation axis J4, the third belt 242c is positioned between the first belt 55 and the second belt 56. With this configuration, when viewed from above in a direction along the second rotation axis J2, the third belt 242c can be arranged to intersect with the first and second belts 55 and 56. This increases the degree of freedom in the placement of the intermediate pulley 54, making it easier to position the intermediate pulley 54 closer to the imaginary center axis A.

[0105] Furthermore, as previously described, the diameter of the first intermediate pulley 541 is larger than that of the second intermediate pulley 542. A weight-reducing portion 541c is formed on the first intermediate pulley 541, extending along the fourth rotation axis J4. This configuration reduces the weight of the intermediate pulley 54, minimizing any degradation in weight balance caused by the intermediate pulley 54.

[0106] Furthermore, as previously described, the robot 1 includes a mounting member 16 disposed on the second arm 12 and carrying the inertial sensor module 6 for measuring the inertia of the second arm 12. Furthermore, when viewed from above along the second rotation axis J2, the mounting member 16 overlaps with the imaginary central axis A. This configuration can suppress deterioration of the weight balance of the second arm 12 caused by the mounting member 16.

[0107] As described above, the robot system 100 includes a robot 1 and a control device 9 for controlling the driving of the robot 1. Furthermore, the robot 1 includes: a base 10; a first arm 11 connected to the base 10 and rotatable relative to the base 10 about a first rotation axis J1; a second arm 12 including an arm base 121 connected to the first arm 11, the second arm 12 rotatable relative to the first arm 11 about a second rotation axis J2 parallel to the first rotation axis J1; a work head 13 disposed on the second arm 12, the work head 13 including a spline shaft 133 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 mounted on the spline shaft 133. When the spline nut 131 is rotated, the spline shaft 133 rotates at least around the third rotation axis J3, and when the ball screw nut 132 is rotated, the spline shaft 133 moves linearly along the third rotation axis J3; and a spline shaft first drive mechanism 23 and a spline shaft second drive mechanism 24 are arranged in the second arm 12, and the spline shaft first drive mechanism 23 rotates the spline nut 131 and the spline shaft 133 rotates at least around the third rotation axis J3, and the spline shaft second drive mechanism 24 rotates the ball screw nut 132 and the spline shaft 133 moves linearly along the third rotation axis J3. The first spline shaft drive mechanism 23 includes a first motor 231 fixed to the arm base 121; a first pulley 51 fixed to the rotation axis of the first motor 231; a second pulley 52 fixed to the spline nut 131; an intermediate pulley 54 that rotates relative to the arm base 121 about a fourth rotation axis J4 parallel to the first rotation axis J1; a first belt 55 looped around the first pulley 51 and the intermediate pulley 54; and a second belt 56 looped around the intermediate pulley 54 and the second pulley 52. ​​The second spline shaft drive mechanism 24 includes a second motor 241 fixed to the arm base 121; a third pulley 242a fixed to the rotation axis of the second motor 241; a fourth pulley 242b fixed to the ball screw nut 132; and a third belt 242c looped around the third pulley 242a and the fourth pulley 242b. Furthermore, when viewed from above along the second rotation axis J2, with the line intersecting the second rotation axis J2 and the third rotation axis J3 as the 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, while the second motor 241 is located on the other side of the imaginary center axis A. Furthermore, a through-hole 121a is formed in the arm base 121, extending through the arm base 121 along the second rotation axis J2. When viewed from above along the second rotation axis J2, the through-hole 121a is located on one side of the imaginary center axis A, that is, offset toward the side where the intermediate pulley 54 is located. With this configuration, the weight reduction provided by the through-hole 121a on the side of the imaginary center axis A can offset at least a portion of the increased weight caused by the intermediate pulley 54. Therefore, the formation of the through-hole 121a improves the weight balance of the second arm 12.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.

[0108] Second embodiment

[0109] Figure 10 It is a plan view showing the interior of a second arm included in the robot according to the second embodiment.

[0110] The robot 1 according to this embodiment is identical to the robot 1 according to the first embodiment, except for the placement of the mounting member 16. It should be noted that the following description of the robot 1 according to this embodiment will focus on the differences from the first embodiment, and descriptions of similarities will be omitted. In the figures of this embodiment, components identical to those in the previous embodiment are denoted by the same reference numerals.

[0111] like Figure 10 As shown, in the robot 1 of this embodiment, when viewed from above along the second rotation axis J2, the loading member 16 is located on the other side of the imaginary central axis A, that is, on the side offset from the intermediate pulley 54. It should be noted that "loading member 16 is located on the other side of the imaginary central axis A" means that, when viewed from above along the second rotation axis J2, the center of gravity of the loading member 16, including the inertial sensor module 6 and the spacer, is located on the other side of the imaginary central axis A. Therefore, as long as the above positional relationship is satisfied, the loading member 16 can be located entirely on the other side of the imaginary central axis A or even on both sides of the imaginary central axis A. With this configuration, the weight increase on the other side of the imaginary central axis A caused by the loading member 16 can partially offset the weight increase on one side of the imaginary central axis A caused by the intermediate pulley 54. Therefore, compared to the first embodiment described above, the through-hole 121a can be smaller, making it easier to form.

[0112] As described above, the robot 1 of this embodiment includes a mounting member 16, which is disposed on the second arm 12 and carries the inertial sensor module 6 for measuring the inertia of the second arm 12. Furthermore, when viewed from above along the second rotational axis J2, the mounting member 16 is located on the other side of the imaginary central axis A, that is, offset from the intermediate pulley 54. This configuration allows the weight increase on the other side of the imaginary central axis A caused by the mounting member 16 to partially offset the weight increase on one side of the imaginary central axis A caused by the intermediate pulley 54. Therefore, compared to the first embodiment described above, the through-hole 121a can be smaller, making it easier to form.

[0113] According to the second embodiment, the same effects as those of the first embodiment can be achieved.

[0114] The robot and robot system of the present invention have been described above based on the illustrated embodiment. However, the present invention is not limited thereto, and the configuration of each part may be replaced with an arbitrary configuration having the same function. In addition, other arbitrary configurations may be added to the present invention. For example, in the aforementioned embodiment, the robot 1 has a pipe 14, but the pipe 14 may be omitted. In this case, the wiring 31 is wound around the base 10 and the second arm 12 via the first arm 11. In addition, in the aforementioned embodiment, the robot 1 is a floor-mounted SCARA robot in which the base 10 is fixed to the ground, etc., but it may also be a suspended SCARA robot in which the base 10 is suspended from the ceiling. In this case, the base 10 is suspended, for example, on a top plate located on the upper part of a stand having a frame-shaped leg.

Claims

1. A robot, characterized in that: have: abutment; a first arm connected to the base and rotating relative to the base around a first rotation axis; a second arm having an arm base connected to the first arm, the second arm being rotatable relative to the first arm about a second rotation axis parallel to the first rotation axis; a working head disposed on the second arm, the working head comprising a spline shaft along a third rotation axis parallel to the first rotation axis, and a spline nut and a ball screw nut mounted on the spline shaft, wherein when the spline nut is rotated, the spline shaft rotates about the third rotation axis, and when the ball screw nut is rotated, the spline shaft moves linearly along the third rotation axis; as well as A first spline shaft drive mechanism and a second spline shaft drive mechanism are arranged in the second arm. The first spline shaft drive mechanism rotates the spline nut to rotate the spline shaft around the third rotation axis, and the second spline shaft drive mechanism 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 the rotating shaft of the first motor; a second pulley fixed to the spline nut; an intermediate pulley rotating around a fourth rotating shaft parallel to the first rotating shaft relative to the arm base; a first belt hung around the first pulley and the intermediate pulley; and a second belt hung 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 the rotating shaft of the second motor; a fourth pulley fixed to the ball screw nut; and a third belt hung around the third pulley and the fourth pulley. When viewed from above along the second rotation axis, and when a straight line intersecting the second rotation axis and the third rotation axis is set as an imaginary central axis of the second arm, the first motor and the intermediate pulley are located on one side of the imaginary central axis, and the second motor is located on the other side of the imaginary central axis. A through hole is formed in the arm base and passes through the arm base in a direction along the second rotation axis. The through hole is arranged offset to the one side of the imaginary central axis when viewed from above in the direction along the second rotation axis.

2. The robot according to claim 1, characterized in that The third rotation axis is located closer to the front end of the second arm than the fourth rotation axis. The through hole is located closer to the third rotation axis than the fourth rotation axis when viewed in plan from a direction along the second rotation axis.

3. The robot according to claim 1, characterized in that The through hole overlaps with the intermediate pulley when viewed from above in a direction along the second rotation axis.

4. The robot according to claim 1, characterized in that The intermediate pulley overlaps the third belt when viewed from above in a direction along the second rotation axis.

5. The robot according to claim 1, characterized in that The intermediate pulley overlaps with the imaginary central axis when viewed from above in a direction along the second rotation axis.

6. The robot according to claim 1, characterized in that The intermediate pulley includes: a shaft portion extending along the fourth rotation axis; a first intermediate pulley disposed on the shaft portion and having the first belt hung thereon; and a second intermediate pulley disposed on the shaft portion and located closer to the arm base than the first intermediate pulley and having the second belt hung thereon. The robot includes a supporting component that is fixed to the arm base, holds a portion of the shaft between the first intermediate pulley and the second intermediate pulley via a first bearing, and holds a portion of the shaft closer to the arm base than the second intermediate pulley via a second bearing.

7. The robot according to claim 6, characterized in that When viewed from above in a direction perpendicular to the fourth rotation axis, the third belt is located between the first belt and the second belt.

8. The robot according to claim 6, characterized in that The diameter of the first intermediate pulley is larger than the diameter of the second intermediate pulley, The first intermediate pulley is provided with a lightening portion that penetrates the first intermediate pulley in a direction along the fourth rotation axis.

9. The robot according to claim 1, characterized in that The robot includes a mounting member, the mounting member being arranged on the second arm and mounting an inertial sensor module for measuring the inertia of the second arm. The placement member overlaps with the imaginary central axis when viewed in plan from a direction along the second rotation axis.

10. The robot according to claim 1, characterized in that The robot has an inertial sensor module, which is configured on the second arm and measures the inertia of the second arm. The inertial sensor module is located on the other side of the imaginary central axis when viewed from above in a direction along the second rotation axis.

11. The robot according to claim 1, characterized in that The third rotation axis is located closer to the front end of the second arm than the fourth rotation axis. When viewed from above along the second rotation axis, the through hole is located closer to the third rotation axis than the fourth rotation axis. When viewed from above along the second rotation axis, the through hole overlaps with the intermediate pulley, the intermediate pulley overlaps with the third belt, and the intermediate pulley overlaps with the imaginary central axis. The intermediate pulley includes: a first intermediate pulley around which the first belt is hung; and a second intermediate pulley arranged along the fourth rotation axis with the first intermediate pulley and around which the second belt is hung. When viewed from above in a direction perpendicular to the fourth rotation axis, the third belt is located between the first belt and the second belt. The diameter of the first intermediate pulley is larger than that of the second intermediate pulley, and a weight-reducing portion is formed on the first intermediate pulley and passes through the first intermediate pulley in a direction along the fourth rotation axis. The robot has an inertial sensor module, which is configured on the second arm. When viewed from above along the second rotation axis, the inertial sensor module overlaps with the imaginary center axis or is located on the other side of the imaginary center axis. The inertial sensor module measures the inertia of the second arm.

12. A robot system, characterized in that: have: Robots; and A control device controls the driving of the robot, The robot has: abutment; a first arm connected to the base and rotating relative to the base around a first rotation axis; a second arm having an arm base connected to the first arm, the second arm being rotatable relative to the first arm about a second rotation axis parallel to the first rotation axis; a working head disposed on the second arm, the working head comprising a spline shaft along a third rotation axis parallel to the first rotation axis, and a spline nut and a ball screw nut mounted on the spline shaft, wherein when the spline nut is rotated, the spline shaft rotates about the third rotation axis, and when the ball screw nut is rotated, the spline shaft moves linearly along the third rotation axis; as well as A first spline shaft drive mechanism and a second spline shaft drive mechanism are arranged in the second arm. The first spline shaft drive mechanism rotates the spline nut to rotate the spline shaft around the third rotation axis, and the second spline shaft drive mechanism 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 the rotating shaft of the first motor; a second pulley fixed to the spline nut; an intermediate pulley rotating around a fourth rotating shaft parallel to the first rotating shaft relative to the arm base; a first belt hung around the first pulley and the intermediate pulley; and a second belt hung 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 the rotating shaft of the second motor; a fourth pulley fixed to the ball screw nut; and a third belt hung around the third pulley and the fourth pulley. When viewed from above along the second rotation axis, and when a straight line intersecting the second rotation axis and the third rotation axis is set as an imaginary central axis of the second arm, the first motor and the intermediate pulley are located on one side of the imaginary central axis, and the second motor is located on the other side of the imaginary central axis. A through hole is formed in the arm base and passes through the arm base in a direction along the second rotation axis. The through hole is arranged offset to the one side of the imaginary central axis when viewed from above in the direction along the second rotation axis.

Images