Robot

Abstract

The present invention provides a robot capable of improving the positional accuracy of the tip of a robot arm.　This robot is characterized in that a second drive unit includes: a second motor; a second output-side rotation transmission member that is fixed to the second arm and transmits the power of the second motor to the second arm; and a second shaft that is fixed to the second output-side rotation transmission member and rotates around a second axis together with the second output-side rotation transmission member; and a third drive unit includes: a third motor; a third output-side rotation transmission member that is fixed to a link included in a link mechanism and transmits the power of the third motor to the link mechanism; and a first bearing that rotatably supports the third output-side rotation transmission member with respect to the second shaft.

Description

Robot

[0001] The present invention relates to a robot.

[0002] In recent years, due to the soaring labor costs and labor shortages in factories, robots with robotic arms are used to perform operations such as material transportation, manufacturing, processing, and assembly, and the automation of operations that have been carried out manually is being attempted.

[0003] For example, Patent Document 1 below discloses a robot having a first arm, a second arm, a third arm, a parallel link, a motor and a speed reducer (first drive unit) for rotationally driving the first arm, and a motor and a speed reducer (second drive unit) for rotationally driving the second arm, and a motor and a speed reducer (third drive unit) for rotationally driving the parallel link.

[0004] WO2021 / 256375

[0005] However, in such a robot, since each drive unit is arranged independently of each other, when vibration occurs in the robotic arm, when an additional load is applied only to one arm, when an assembly error occurs, etc., each drive unit may deviate from its original rotation axis. When each drive unit deviates from its original rotation axis in this way, there is a problem that the positional accuracy of the tip of the robotic arm deteriorates and accurate work cannot be performed.

[0006] A robot according to an application example of the present invention comprises: a first arm installed along a first axis; a second arm rotatably connected to the first arm around a second axis not parallel to the first axis; a third arm rotatably connected to the second arm around a third axis parallel to the second axis; a link mechanism for transmitting power to rotate the third arm to the third arm; a second drive unit installed on the first arm for rotationally driving the second arm; and a third drive unit installed on the first arm for rotationally driving the third arm, wherein the second drive unit comprises: a second motor; a second output-side rotational transmission member fixed to the second arm for transmitting power from the second motor to the second arm; and a second shaft fixed to the second output-side rotational transmission member and rotating together with the second output-side rotational transmission member around the second axis. The third drive unit includes a third motor, a third output-side rotational transmission member fixed to a link of the link mechanism and transmitting power from the third motor to the link mechanism, and a first bearing that rotatably supports the third output-side rotational transmission member with respect to the second shaft.

[0007] This is a perspective view showing a robot system according to the first embodiment of the present invention. This is a left side view showing a part of the robot in Figure 1. This is a right side view showing a part of the robot in Figure 1. This is a cross-sectional view along the line IV-IV in Figure 2. This is a plan view of the first arm of the robot shown in Figure 1. This is a cross-sectional view along the line VI-VI in Figure 1. This is a cross-sectional view along the line VII-VII in Figure 1. This is a cross-sectional view along the line VIII-VIII in Figure 2. This is a left side view showing the range of motion of the plate-shaped link of the second arm and link mechanism of the robot shown in Figure 1. This is a left side view showing the range of motion of the fourth arm of the robot shown in Figure 1. This is a cross-sectional view of the second joint of the robot according to the second embodiment of the present invention.

[0008] <First Embodiment> Embodiments of the present invention will be described below with reference to the drawings. The following description does not limit the technical scope or the meaning of terms described in the claims. Furthermore, the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from actual ratios.

[0009] Figure 1 is a perspective view showing a robot system 1 according to the first embodiment. Figure 2 is a left side view showing a part of the robot 10 in Figure 1. Figure 3 is a right side view showing a part of the robot 10 in Figure 1. Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 2. Figure 5 is a plan view of the first arm 121 of the robot 10 shown in Figure 1. Figure 6 is a cross-sectional view taken along the line VI-VI in Figure 1. Figure 7 is a cross-sectional view taken along the line VII-VII in Figure 1. Figure 8 is a cross-sectional view taken along the line VIII-VIII in Figure 2. Figure 9 is a left side view showing the range of motion of the second arm 122 and the plate-shaped link 131a of the link mechanism 131 of the robot 10 shown in Figure 1. Figure 10 is a left side view showing the range of motion of the fourth arm 124 of the robot 10 shown in Figure 1.

[0010] For the sake of clarity, in the following diagrams, the x-axis, y-axis, and z-axis are represented by arrows as three mutually orthogonal axes. In this embodiment, the x-axis is an axis along one of the horizontal directions, the y-axis is an axis along a direction perpendicular to the x-axis in the horizontal direction, and the z-axis is an axis along the vertical direction. The tip of each arrow shown is referred to as the "positive side (+)" and the base end as the "negative side (-)". The z-axis direction + is referred to as "up" or "upward", and the z-axis direction - is referred to as "down" or "downward".

[0011] Furthermore, in this specification, descriptions such as "orthogonal," "parallel," "same position, height, dimensions, etc.," and "symmetrical" all mean that they are "orthogonal," "parallel," "same position, height, dimensions, etc.," and "symmetrical" to a degree that allows for manufacturing tolerances. Specifically, "orthogonal" means substantially orthogonal, and includes the range in which the angle between two lines or two planes is 80 degrees or more and 100 degrees or less. "Parallel" means substantially parallel, and includes the range in which the angle between two lines or two planes is 0 degrees or more and 10 degrees or less. "Same dimensions" means that the two dimensions are substantially the same, and includes the range in which the error between the two dimensions is ±10%. "Symmetrical" means substantially symmetrical, and includes the range in which, when one of the two elements is superimposed on the other, the ratio of the overlapping area to the total area of ​​the other is 90% or more and 100% or less.

[0012] Furthermore, in Figure 5, the second motor 151 and the third motor 161, which will be described later, are omitted. Also, in Figure 8, the second motor 151, which is located on the negative side of the y-axis direction than the cross-section in Figure 8, is virtually shown by a dashed line.

[0013] Robot system 1 is used in the broad sense of food manufacturing, including, for example, food transport, food plating, food packaging, and food processing. In this case, the workpiece (object to be worked on) in robot system 1 is food or food packaging. However, the application of robot system 1 and the type of workpiece are not limited to the above.

[0014] Referring to Figure 1, the robot system 1 comprises a robot 10 and a control device 20 that controls the operation of each part of the robot 10. The robot 10 has a base 110 on which a drive unit 140 is provided, and a robot arm 200 that is rotatably connected to the base 110 via joints 125 and rotates relative to the base 110 by the drive of the drive unit 140. The robot arm 200 includes a plurality of arms 121, 122, 123, 124 that are sequentially rotatably connected, a plurality of joints 125, 126, 127, 128, link mechanisms 131, 132, and a plurality of drive units 150, 160, 170. The parts of the robot system 1 will be described in detail below.

[0015] The base 110 is a support for the robot arm 200. The base 110 is installed on a horizontal surface (installation surface) parallel to the x-y plane, such as the floor or ceiling of a factory.

[0016] Hereinafter, the arm 121 of the robot arm 200 will also be referred to as the "first arm 121", the arm 122 as the "second arm 122", the arm 123 as the "third arm 123", and the arm 124 as the "fourth arm 124". Also, the joint 125 will be referred to as the "first joint 125", the joint 126 as the "second joint 126", the joint 127 as the "third joint 127", and the joint 128 as the "fourth joint 128". Furthermore, in the robot 10, the robot arm 200, and each of the arms 121, 122, 123, 124, etc., the side facing the base 110 will also be referred to as the "base end side" or "base end", and the opposite side will also be referred to as the "tip end side" or "tip end".

[0017] The shapes of the first arm 121, the second arm 122, the third arm 123, and the fourth arm 124 are not particularly limited, but in this embodiment, each has an overall elongated shape or a similar shape.

[0018] The first arm 121 is provided above the base 110 along a first axis A1 parallel to the z-axis direction. The base end (lower end) of the first arm 121 is rotatably connected to the base 110 via a first joint 125, so as to the first axis A1. When the first shaft, which rotates around the first axis A1, is driven by a drive unit 140 including a first motor (not shown), the first arm 121 rotates in a predetermined direction relative to the base 110, the entire robot arm 200, that is, the first arm 121 and the second joint 126, second arm 122, third joint 127, third arm 123, fourth joint 128, fourth arm 124, link mechanisms 131, 132, etc., which are located on the tip side of the first arm 121, rotate counterclockwise or clockwise around the first axis A1. In other words, the first shaft rotates around the first axis A1 due to the drive of the drive unit 140, which includes a first motor (not shown), causing the entire robot arm 200 to rotate around the first rotation axis.

[0019] The base end of the second arm 122 is rotatably connected to the tip (upper end) of the first arm 121 via the second joint 126, around the second axis A2 which extends in a direction nonparallel to the first axis A1, and in this embodiment in a direction perpendicular to the first axis A1 (the x-axis direction when the rotation angle of the first arm 121 is as shown in Figure 1). The second arm 122 extends along the direction perpendicular to the second axis A2.

[0020] The portion of the third arm 123 between its base and tip is rotatably connected to the tip of the second arm 122 via a third joint 127, so as to be around a third axis A3 parallel to the second axis A2. The third arm 123 extends in a direction perpendicular to the third axis A3.

[0021] The base end of the fourth arm 124 is connected to the tip of the third arm 123 via the fourth joint 128, so as to be rotatable (oscillating) around the fourth axis A4 which is parallel to the second axis A2.

[0022] An end effector E1 is detachably provided at the tip of the fourth arm 124 for holding a workpiece (e.g., food) by gripping or suction. The end effector E1 is mounted on the tip of the fourth arm 124 so as to be rotatable around a fifth axis A5 parallel to the z-axis direction. The end effector E1 may or may not be a component of the robot 10.

[0023] Hereinafter, the direction along the first axis A1 will also be referred to as the "first direction D1," the direction along the second axis A2 will also be referred to as the "second direction D2," and the direction perpendicular to the first direction D1 and the second direction D2 will also be referred to as the "third direction D3." In this embodiment, the first direction D1 coincides with the z-axis direction. In this embodiment, the second direction D2 and the third direction D3 are directions parallel to the x-y plane, and their orientation changes with the rotation of the first arm 121. The first direction D1, the second direction D2, and the third direction D3 are illustrated with arrows in each figure. For the first direction D1, the second direction D2, and the third direction D3, the tip of each arrow will be referred to as the "positive side (+ side)," and the base end as the "negative side (- side)."

[0024] The drive unit 140 rotates the first arm 121. Hereinafter, the drive unit 140 will also be referred to as the "first drive unit 140". The drive unit 150 rotates the second arm 122. Hereinafter, the drive unit 150 will also be referred to as the "second drive unit 150". The drive unit 160 rotates the third arm 123. Hereinafter, the drive unit 160 will also be referred to as the "third drive unit 160". The second drive unit 150 and the third drive unit 160 are installed on the first arm 121. The drive unit 170 rotates the end effector E1. Hereinafter, the drive unit 170 will also be referred to as the "fourth drive unit 170". The fourth drive unit 170 is installed on the fourth arm 124.

[0025] The first drive unit 140 and the fourth drive unit 170 each include a motor and a power transmission unit that transmits the rotational driving force (hereinafter simply referred to as "power") of the motor, although these are not shown. The drive of each motor is controlled by a control device 20, which will be described later, via a motor driver, which is not shown. The power transmission unit preferably includes a reduction gear that transmits the power of the motor at a reduced rotational speed. Examples of reduction gears include gear devices such as planetary gears and harmonic drive gears, and winding transmission devices (winding reduction gears). A winding transmission device is a device that transmits power by wrapping an annular member around a pair of rotational transmission members. Examples of combinations of rotational transmission members and annular members include a pulley-belt mechanism in which the rotational transmission member is composed of a pulley and the annular member is composed of a belt, a sprocket-chain mechanism in which the rotational transmission member is composed of a sprocket and the annular member is composed of a chain, and a wheel-wire mechanism in which the rotational transmission member is composed of a wheel and the annular member is composed of a wire. Details of the configurations of the second drive unit 150 and the third drive unit 160 will be described later.

[0026] The link mechanism 131 transmits the power output by the third drive unit 160 to the third arm 123. As shown in Figure 2, the link mechanism 131 includes a long plate-shaped link 131a, a rod-shaped link 131b, a pivot 131c, and a pivot 131d.

[0027] As will be described in more detail later, the base end of link 131a is positioned on the second axis A2, and link 131a extends in a direction perpendicular to the second axis A2 and rotates around the second axis A2 independently of the second arm 122 by the drive of the third drive unit 160. The tip of link 131a is rotatably connected to the base end of a rod-shaped link 131b via a pivot 131c around an axis parallel to the second axis A2. The tip of link 131b is rotatably connected to the base end of the third arm 123 via a pivot 131d around an axis parallel to the second axis A2.

[0028] The length of the line L1 connecting the second axis A2 and the central axis of pivot 131c is the same as the length of the line L2 connecting the third axis A3 and the central axis of pivot 131d. The distance between the second axis A2 and the third axis A3 is the same as the distance between the central axis of pivot 131c and the central axis of pivot 131d. Therefore, when viewed from the second direction D2 (the x-axis direction in Figure 2), the line segments connecting the second axis A2, the central axis of pivot 131c, the central axis of pivot 131d, the third axis A3, and the second axis A2 in sequence form a parallelogram.

[0029] Therefore, when viewed from the second direction D2, the line L1 is parallel to the line L2. Consequently, when the link 131a rotates by a predetermined angle in a predetermined direction (for example, counterclockwise in Figure 2) due to the drive of the third drive unit 160, the line L1 also rotates in the same direction by the same angle, and the third arm 123 rotates around the third axis A3 so that the line L2 is parallel to the line L1.

[0030] As shown in Figure 1, the link mechanism 132 is provided on the second direction D2+ side of the link mechanism 131. The link mechanism 132 maintains a constant posture of the fourth arm 124 so that the fifth axis A5, which is the rotation axis of the end effector E1 mounted on the fourth arm 124, is always parallel to the z-axis direction. As shown in Figure 3, the link mechanism 132 has a rod-shaped link 132a, a plate-shaped link 132b, a rod-shaped link 132c, a pivot 132d, a pivot 132e, a pivot 132f, and a pivot 132g. The shape of the plate-shaped link 132b is a triangular shape with rounded corners.

[0031] Link support members 121e are provided at the ends of the first arm 121 on the second direction D2+ side and the third direction D3+ side (the ends opposite to the side facing the fourth arm 124), projecting above the upper end of the first arm 121. The base end of the rod-shaped link 132a is rotatably connected by a pivot 132d to the tip (upper end) of the link support member 121e around a rotation axis parallel to the second axis A2.

[0032] The tip of the rod-shaped link 132a and one corner of the plate-shaped link 132b are rotatably connected by a pivot 132e around an axis of rotation parallel to the second axis A2. The other corner of the plate-shaped link 132b and the base end of the rod-shaped link 132c are rotatably connected by a pivot 132f around an axis of rotation parallel to the second axis A2. The tip of the rod-shaped link 132c and the portion of the base end of the fourth arm 124 that is separated from the fourth joint 128 are rotatably connected by a pivot 132g around an axis of rotation parallel to the second axis A2. The remaining corner of the plate-shaped link 132b is rotatably connected to the third arm 123 via the third joint 127 around the third axis A3.

[0033] The length of the line L3 connecting the second axis A2 and the central axis of pivot 132d is the same as the length of the line L4 connecting the third axis A3 and the central axis of pivot 132e. The distance between the second axis A2 and the third axis A3 is the same as the distance between the central axis of pivot 132d and the central axis of pivot 132e. Therefore, when viewed from the second direction D2 (the x-axis direction in Figure 3), line L3 is parallel to line L4.

[0034] Furthermore, the length of the line L5 connecting the third axis A3 and the central axis of pivot 132f is the same as the length of the line L6 connecting the fourth axis A4 and the central axis of pivot 132g. The distance between the third axis A3 and the fourth axis A4 is the same as the distance between the central axis of pivot 132f and the central axis of pivot 132g. Therefore, when viewed from the second direction D2, line L5 is parallel to line L6.

[0035] The angle of the straight line L3 with respect to the x-y plane does not change with the rotation angles (positions) of the second arm 122 and the third arm 123. Therefore, the angle of the straight line L4 with respect to the x-y plane remains constant. Consequently, the position of the plate-shaped link 132b also remains constant. Consequently, the angle of the straight line L5 with respect to the x-y plane also remains constant. Therefore, the angle of the straight line L6 with respect to the x-y plane also remains constant. From the above, the position of the fourth arm 124 is kept constant regardless of the rotation angles (positions) of the second arm 122 and the third arm 123.

[0036] As described above, by controlling the rotation angles of the first arm 121, the second arm 122, and the third arm 123, the position of the end effector E1 in the xyz coordinate system can be adjusted while keeping the fifth axis A5, which is the rotation axis of the end effector E1, parallel to the z-axis direction. Furthermore, by rotating the end effector E1 around the fifth axis A5, the workpiece held by the end effector E1 can be rotated. Note that the specific shapes of each arm 121, 122, 123, 124, link mechanism 131, and link mechanism 132 are not particularly limited to the shapes shown in the figure.

[0037] As shown in Figure 1, the control device 20 is connected to each part of the robot 10 by wire or wireless means to enable the transmission and reception of signals, and controls the operation of each part of the robot 10. The control device 20 includes an arithmetic unit 201 composed of a processor such as a CPU (Central Processing Unit), a storage unit 202 composed of volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory), and a communication unit 203 that transmits and receives signals to each part of the robot 10 (including the drive units 140, 150, 160, 170, the second encoder E2, and the third encoder E3, which will be described later). In this embodiment, the control device 20 is located outside the robot 10. However, the control device 20 may be installed on a base 110 or the like.

[0038] Next, the first arm 121, the second joint 126, the second drive unit 150, and the third drive unit 160 will be described in detail.

[0039] The first arm 121 has an arm base 121a on which the second drive unit 150 and the third drive unit 160 are installed. In the following, the assembly of the first arm 121, the second drive unit 150 and the third drive unit 160, which corresponds to the body of the robot arm 200, will also be referred to as the "base end of the robot arm 200".

[0040] As shown in Figure 1, the arm base 121a includes a bottom plate portion 121b having an upper surface parallel to the x-y plane, and a pair of side plate portions 121c and 121d connected to both ends of the bottom plate portion 121b in the second direction D2 and extending along the z-axis direction. The arm base 121a is a housing that has an open upper surface (a surface parallel to the x-y plane), and a shape in which parts of the positive and negative sides of the third direction D3 (surfaces parallel to the x-z plane), which are perpendicular to the side plate portions 121c and 121d, are open. Inside the housing, a space is formed that can accommodate the main parts of the second drive unit 150 and the third drive unit 160.

[0041] As shown in Figure 4, the shape of the bottom plate portion 121b in a top view is a rectangle with rounded corners. In this embodiment, the first axis A1 is located at the center of the bottom plate portion 121b in a top view.

[0042] One side plate portion 121c is connected to the end of the bottom plate portion 121b on the second direction D2- side. The one side plate portion 121c has a flat main body portion 121f parallel to the first direction D1 and the third direction D3, and a pair of protrusions 121g projecting from both ends of the main body portion 121f in the third direction D3 toward the other side plate portion 121d.

[0043] The other side plate portion 121d is connected to the end of the bottom plate portion 121b on the second direction D2+ side. The other side plate portion 121d has a shape that coincides with the other side plate portion 121c when rotated 180 degrees around the first axis A1 as the central axis. In other words, the pair of side plate portions 121c and 121d are rotationally symmetric with respect to the first axis A1. Therefore, parts of the same shape can be used for the pair of side plate portions 121c and 121d. This reduces the number of types of parts that need to be prepared to manufacture the robot 10, and allows for efficient manufacturing of the robot 10. As a result, the productivity of the robot 10 is improved. Each side plate portion 121c and 121d is attached to the bottom plate portion 121b by screws or the like.

[0044] However, the shape of the arm base 121a of the first arm 121 is not limited to the above. For example, the arm base 121a may be attached to the end portion on the D3- side of the bottom plate portion 121b and further have a front plate portion extending in the z-axis direction, or may be attached to the end portion on the D3+ side of the bottom plate portion 121b and further have a back plate portion extending in the z-axis direction. Further, the arm base 121a may be formed by integrally forming the bottom plate portion 121b, the side plate portion 121c, and the side plate portion 121d. For example, it may be formed by shaping a single metal plate into a desired shape by press working or the like. Also, the first axis A1 may be located at a position deviated from the center in the top view of the first arm 121.

[0045] Such an arm base 121a has sufficiently high rigidity and does not easily deform. Therefore, the shape retention of the entire first arm 121 can be ensured, and members attached to the arm base 121a, such as the bearing holders 126s and 126t, can be stably held, and the attachment position accuracy of the members is also excellent.

[0046] As shown in FIG. 8, the second joint 126 that rotatably connects the second arm 122 to the first arm 121 around the second axis A2 is provided at the upper portions of the pair of side plate portions 121c and 121d. The second joint 126 has a shaft 126a provided along the second axis A2, a bearing portion 126b that rotatably holds one end portion (the end portion on the x-axis - side) of the shaft 126a, and a bearing portion 126c that rotatably holds the other end portion (the end portion on the x-axis + side) of the shaft 126a. The shaft 126a may belong to the second drive unit 150 as a component of the second drive unit 150. The shaft 126a is sometimes referred to as the "second shaft".

[0047] The shaft 126a is a solid or hollow rod-shaped member with a circular cross-section, and has two stepped portions 126j and 126k formed at a predetermined distance along the second axis A2 direction. When viewed in the second axis A2 direction, the portion between the stepped portions 126j and 126k of the shaft 126a has a larger outer diameter than the other portions, that is, the portion on the x-axis - side of the stepped portion 126j of the shaft 126a and the portion on the x-axis + side of the stepped portion 126k. Hereinafter, the portion between the stepped portions 126j and 126k of the shaft 126a is referred to as the large-diameter portion, and the other portions are referred to as the small-diameter portions.

[0048] As shown in FIG. 5, the shaft 126a is located at the center in the third direction D3 of the bottom plate portion 121b when viewed from the first direction D1 (z-axis direction), and extends along the second axis A2 direction from one side plate portion 121c to the other side plate portion 121d. Therefore, in the present embodiment, the second axis A2, which is the central axis of the shaft 126a, is orthogonal to the first axis A1. As shown in FIG. 8, the base end portion of the second arm 122 is fixed to the portion between the pair of side plate portions 121c and 121d of the shaft 126a, more specifically, to the large-diameter portion of the shaft 126a, via an output-side rotation transmission member 155b described later, and the second arm 122 rotates in conjunction with the shaft 126a.

[0049] Note that, unlike the illustration, the second arm 122 may be directly fixed to the shaft 126a. In this case, the second arm 122 may or may not be fixed to the output-side rotation transmission member 155b.

[0050] The bearing portion 126b includes a bearing 126d (bearing) whose inner ring is fixed to the outer periphery of the small-diameter portion of the shaft 126a, for example, by press-fitting, and a bearing holder 126s that holds the outer ring of the bearing 126d and is attached to the arm base 121a of the first arm 121. The end face on the x-axis + side of the inner ring of the bearing 126d abuts against the stepped portion 126j.

[0051] The bearing portion 126c includes a bearing 126e (bearing) whose inner ring is fixed to the outer periphery of the small-diameter portion of the shaft 126a, for example, by press-fitting, and a bearing holder 126t that holds the outer ring of the bearing 126e and is attached to the arm base 121a of the first arm 121.

[0052] The bearing portion 126b is attached to the upper part of the side plate portion 121c of the first arm 121. The bearing portion 126c is attached to the upper part of the side plate portion 121d of the first arm 121.

[0053] Furthermore, a through hole 131h is formed at the base end of the link 131a of the link mechanism 131, with a diameter larger than the diameter of the shaft 126a, and passing through the link 131a in the thickness direction. The link 131a is positioned on the second direction D2+ side of the second arm 122, spaced apart from the second arm 122, with the shaft 126a inserted through the through hole 131h.

[0054] Furthermore, a second drive unit 150 and a third drive unit 160 are installed on the arm base 121a of the first arm 121. The second drive unit 150 includes a second motor 151 and a second power transmission unit 152 that transmits the power of the second motor 151 to the shaft 126a. Similarly, the third drive unit 160 includes a third motor 161 and a third power transmission unit 162 that transmits the power of the third motor 161 to the link 131a of the link mechanism 131.

[0055] As shown in Figure 2, the second motor 151 and the third motor 161 are spaced apart from the shaft 126a of the second joint 126 in the first direction D1-. As shown in Figure 4, the second motor 151 and the third motor 161 are positioned between a pair of side plates 121c and 121d, on the bottom plate 121b. That is, the second motor 151 and the third motor 161 are housed in the arm base 121a. Therefore, even if foreign matter such as lubricating oil leaks or scatters from the second motor 151 and the third motor 161, the side plates 121c and 121d function as protective walls, preventing the foreign matter from leaking or scattering outside the arm base 121a. As mentioned above, when the workpiece is food or food packaging, the adhesion or contamination of foreign matter must be avoided, so applying the robot 10 with the above configuration to food manufacturing is meaningful. However, parts of the second motor 151 and the third motor 161 may protrude outside the arm base 121a.

[0056] The second motor 151 includes a rotor and stator (not shown), a second output shaft 151a fixed to the rotor, and a second housing 151b that houses the rotor and stator and exposes the tip of the second output shaft 151a. As shown in Figure 8, the second motor 151 is attached to the upper surface of the bottom plate portion 121b via a mount 151c. As shown in Figures 1 and 4, the second motor 151 is installed such that the second output shaft 151a extends along the second direction D2, and the second output shaft 151a protrudes from the second housing 151b toward the second direction D2-. Furthermore, the second motor 151 is positioned toward the third direction D3- side of the second shaft A2 when viewed from the first direction D1.

[0057] The second motor 151 is energized by the control device 20 controlling a motor driver (not shown), and its drive is controlled as desired.

[0058] Similarly, the third motor 161 includes a rotor and stator (not shown), a third output shaft 161a fixed to the rotor, and a third housing 161b that houses the rotor and stator and exposes the tip of the third output shaft 161a. The third motor 161 is mounted on the upper surface of the bottom plate portion 121b via a mount 161c. The third motor 161 is installed such that the third output shaft 161a extends along the second direction D2, and the third output shaft 161a protrudes from the third housing 161b toward the second direction D2+. Furthermore, the third motor 161 is positioned toward the third direction D3+ side than the second shaft A2 when viewed from the first direction D1.

[0059] The third motor 161 is energized by the control device 20 controlling a motor driver (not shown), and its drive is controlled as desired.

[0060] The model number of the second motor 151 and the model number of the third motor 161 are the same. That is, the motor type (such as servo motor or stepping motor), performance (such as output torque and rotational speed), and shape of the second motor 151 and the third motor are the same. The output torque of the second motor 151 and the third motor 161 is not particularly limited, but is preferably 0.1 N·m or more and 10 N·m or less, and more preferably 0.5 N·m or more and 5 N·m or less.

[0061] Here, the positional relationship between the second motor 151 and the third motor 161 will be described. The second motor 151 and the third motor 161 are positioned opposite each other in the third direction D3. Specifically, in this embodiment, the side surface of the second housing 151b and the side surface of the third housing 161b face each other in the third direction D3 via the first axis A1. In this specification, when two elements face each other in a particular direction, it means that, when viewed from that particular direction, the two elements overlap at least partially. In this case, the two elements may be in contact or separated. In this embodiment, the second housing 151b and the third housing 161b are separated. Therefore, good heat dissipation of the second motor 151 and the third motor 161 can be maintained, and direct transmission of vibration between the second motor 151 and the third motor 161 is avoided, which also contributes to preventing the generation of noise due to resonance, etc.

[0062] Thus, the second output shaft 151a and the third output shaft 161a extend along the second direction D2, and the second motor 151 and the third motor 161 face each other in the third direction D3, which is perpendicular to the second direction D2 to which the second output shaft 151a and the third output shaft 161a extend. Therefore, compared to the case where the second output shaft 151a and the third output shaft 161a are arranged on the same straight line extending in the second direction D2 (where the second motor 151 and the third motor 161 are coaxial), the second motor 151 and the third motor 161 can be arranged more compactly in the second direction D2. This allows the base end of the robot arm 200 to be miniaturized in the second direction D2. As a result, the robot 10 is less likely to interfere with surrounding objects, thus increasing the degree of freedom in installing the robot 10. Furthermore, in the robot 10 according to this embodiment, the first arm 121 rotates around the first axis A1, and interference between the base end of the robot arm 200 and surrounding objects can be suitably suppressed when the first arm 121 rotates.

[0063] Furthermore, the boundary surface P1 is defined as a plane passing through the second axis A2 and parallel to the first direction D1 and the second direction D2 (a plane parallel to the x-z plane). The second output shaft 151a and the third output shaft 161a are located on opposite sides of the boundary surface P1. More specifically, the entire second motor 151 is located on the third direction D3- side of the boundary surface P1, and the entire third motor 161 is located on the third direction D3+ side of the boundary surface P1. However, the configuration is not limited to the above, and at least one of the second housing 151b and the third housing 161b may straddle the boundary surface P1.

[0064] This allows for a better balance of the shape, structure, component arrangement, and weight of the base end of the robot arm 200 compared to the case where the second output shaft 151a and the third output shaft 161a are positioned off-center to one side in the third direction D3 relative to the interface P1. Furthermore, the base end of the robot arm 200 can be miniaturized in the third direction D3. As a result, the robot 10 is less likely to interfere with its surroundings, increasing the freedom of placement for the robot 10. Also, as shown in Figure 10, when the fourth arm 124 is moved to approach the first arm 121, the range of motion of the fourth arm 124 on the third direction D3+ side is the range up to just before the fourth arm 124 interferes with the first arm 121. Therefore, by miniaturizing the base end of the robot arm 200 in the third direction D3, the range of motion of the fourth arm 124 on the third direction D3+ side can be expanded. This expands the movable range of the end effector E1.

[0065] Furthermore, as shown in Figure 4, when viewed from the first direction D1, the external shape of the second motor 151 matches that of the third motor 161 when rotated 180 degrees around the first axis A1. In other words, the second motor 151 and the third motor 161 are point-symmetric with respect to the first axis A1 when viewed from the first direction D1. Therefore, the balance of the arrangement of components at the base end of the robot arm 200 and the weight balance can be improved.

[0066] Furthermore, as shown in Figure 8, the position (height) of the second output shaft 151a in the third direction D3 is the same as the position (height) of the third output shaft 161a in the third direction. Moreover, when viewed from the third direction D3 (y-axis direction in Figure 8), the outer shape of the second motor 151 matches the outer shape of the third motor 161 when the first axis A1 is inverted as the central axis. In other words, the second motor 151 and the third motor 161 are symmetrical with respect to the first axis A1 when viewed from the third direction D3. Therefore, the balance of the arrangement of components at the base end of the robot arm 200 and the weight balance can be improved.

[0067] Based on the above, in this embodiment, the external shape of the second motor 151 matches that of the third motor 161 when rotated 180 degrees around the first axis A1 as the central axis. In other words, the second motor 151 and the third motor 161 are rotationally symmetric with respect to the first axis A1.

[0068] However, the configuration and arrangement of the second motor 151 and the third motor 161 are not limited to those described above. For example, the type of the second motor 151 and the type of the third motor 161 may be different. Also, for example, the positions of the second motor 151 and the third motor 161 in the first direction D1 do not have to coincide. Also, for example, the second motor 151 and the third motor 161 do not have to be point-symmetric with respect to the first axis A1 when viewed from the first direction D1, nor do they have to be line-symmetric with respect to the first axis A1 when viewed from the third direction D3.

[0069] In this embodiment, the second power transmission section 152 of the second drive unit 150 includes a reduction gear that transmits the power of the second motor 151 at a reduced rotational speed. In this embodiment, the reduction gear is composed of a multi-stage reduction type winding transmission device, more specifically a multi-stage reduction type pulley-belt mechanism. If a gear device were used as the reduction gear, it would be necessary to periodically apply lubricating oil between the gears to suppress gear wear. In contrast, if a pulley-belt mechanism is used as the reduction gear, it is not necessary to apply lubricating oil between the pulley and the belt. Therefore, maintenance of the robot 10 is made easier, and it is possible to suppress the leakage or scattering of lubricating oil from the robot 10 and contaminating the workpiece or installation surface. As mentioned above, if the workpiece is food or food packaging, the adhesion or contamination of lubricating oil must be avoided, and separate sufficient preventive measures would be necessary, but in this embodiment, such measures are not necessary or simpler measures suffice.

[0070] Furthermore, winding drive systems are lighter and less expensive than gear systems such as planetary gears and harmonic drive gears. Therefore, it is possible to reduce the weight of the robot arm 200 and the cost of the robot 10. As the robot arm 200 becomes lighter, the inertial force during rotational drive of the first arm 121 and other components of the robot arm 200 is reduced, allowing the rotational drive of the first arm 121 and other components to be performed at a higher speed, thereby improving work efficiency by increasing the work speed.

[0071] Specifically, as shown in Figure 6, the second power transmission unit 152, as a reduction gear, includes an input-side rotational transmission member 153a provided on the second output shaft 151a, a first-stage rotating shaft 153s spaced apart from the second output shaft 151a, an output-side rotational transmission member 153b provided on the first-stage rotating shaft 153s, and an annular member 153c wrapped around the input-side rotational transmission member 153a and the output-side rotational transmission member 153b. Hereinafter, these will also be referred to as the "first-stage reduction gear." The output-side rotational transmission member 153b corresponds to the "first rotational transmission member," and the rotating shaft 153s corresponds to the first rotating shaft. The input-side rotational transmission member 153a is a small-diameter pulley, the output-side rotational transmission member 153b is a large-diameter pulley with a diameter greater than the diameter of the input-side rotational transmission member 153a, and the annular member 153c is an endless belt.

[0072] Furthermore, the second power transmission unit 152, as a reduction gear, includes an input-side rotational transmission member 154a provided on the first-stage rotating shaft 153s, a second-stage rotating shaft 154s spaced apart from the first-stage rotating shaft 153s, an output-side rotational transmission member 154b provided on the second-stage rotating shaft 154s, and an annular member 154c wrapped around the input-side rotational transmission member 154a and the output-side rotational transmission member 154b. Hereinafter, these will also be referred to as the "second-stage reduction gear." The input-side rotational transmission member 154a is a small-diameter pulley with the same diameter as the input-side rotational transmission member 153a of the first stage. The output-side rotational transmission member 154b is a large-diameter pulley with the same diameter as the output-side rotational transmission member 153b of the first stage, and the annular member 154c is an endless belt with the same width, thickness, and circumference as the annular member 153c of the first stage.

[0073] Furthermore, the second power transmission unit 152, as a reduction gear, includes an input-side rotational transmission member 155a (second input-side transmission member) provided on the second-stage rotating shaft 154s, an output-side rotational transmission member 155b (second output-side transmission member) provided on the shaft 126a of the second joint 126, and an annular member 155c (second annular member) wrapped around the input-side rotational transmission member 155a and the output-side rotational transmission member 155b. Hereinafter, these will also be referred to as the "third-stage reduction gear". The input-side rotational transmission member 155a is a small-diameter pulley, the output-side rotational transmission member 155b is a large-diameter pulley whose diameter is larger than that of the input-side rotational transmission member 155a, and the annular member 155c is an endless belt. As shown in Figure 8, the output-side rotational transmission member 155b is provided between the second arm 122 and the side plate portion 121c.

[0074] The diameter of the third-stage input-side rotational transmission member 155a is greater than the diameter of the first-stage input-side rotational transmission member 153a. The diameter of the third-stage output-side rotational transmission member 155b is greater than the diameter of the first-stage output-side rotational transmission member 153b. The width of the third-stage annular member 155c is greater than the width of the first-stage annular member 153c, and the thickness of the third-stage annular member 155c is greater than the thickness of the first-stage annular member 153c.

[0075] As shown in Figure 6, when viewed from the second direction D2, the first stage rotation shaft 153s is located above the second output shaft 151a (towards the z+ direction) and towards the third direction D3+, and is situated on the first axis A1. Similarly, the second stage rotation shaft 154s is located above the first stage rotation shaft 153s and is situated on the first axis A1. Therefore, the first stage rotation shaft 153s, the second stage rotation shaft 154s, and the second axis A2 are aligned in the first direction D1, and when viewed from the second direction D2, they are all located on the first axis A1.

[0076] As shown in Figure 8, the end of the first stage rotating shaft 153s on the second direction D2- side is provided with a bearing portion 153t that rotatably holds the first stage rotating shaft 153s. In this embodiment, the bearing portion 153t is composed of a bearing and a bearing holder. The same applies to the second power transmission portion 152 and the third power transmission portion 162, which will be described later, except for the bearing portion 166 which will be described later. The bearing portion 153t is attached to the side plate portion 121c. On the first stage rotating shaft 153s, the output side rotation transmission member 153b of the first stage and the input side rotation transmission member 154a of the second stage are provided in order toward the second direction D2+ side, spaced apart from each other.

[0077] Similarly, the end of the second stage rotating shaft 154s on the second direction D2- side is provided with a bearing portion 154t that rotatably holds the rotating shaft 154s. The bearing portion 154t is attached to the side plate portion 121c. On the second stage rotating shaft 154s, the third stage input-side rotation transmission member 155a and the second stage output-side rotation transmission member 154b are provided in order toward the second direction D2+ side, spaced apart from each other.

[0078] Furthermore, the input-side rotational transmission members 153a, 154a, 155a, output-side rotational transmission members 153b, 154b, 155b, and annular members 153c, 154c, 155c that constitute the second power transmission unit 152 are all positioned between the pair of side plate portions 121c, 121d of the first arm 121. In other words, they are housed in the arm base 121a of the first arm 121. Therefore, even if foreign matter such as shavings of the annular members 153c, 154c, 155c are scattered from the second power transmission unit 152, the side plate portions 121c, 121d function as protective walls, preventing the foreign matter from scattering outside the arm base 121a. As mentioned above, when the workpiece is food or food packaging, the adhesion or contamination of foreign matter must be avoided, so applying the robot 10 with the above configuration to food manufacturing is meaningful. However, some of these may protrude outward from the arm base 121a of the first arm 121.

[0079] As a result, when the second output shaft 151a rotates due to the drive of the second motor 151, the first stage input-side rotation transmission member 153a of the second power transmission unit 152 rotates in conjunction with it. In conjunction with this, the first stage annular member 153c, the output-side rotation transmission member 153b, the first stage rotating shaft 153s, and the second stage input-side rotation transmission member 154a rotate. Further in conjunction with this, the second stage annular member 154c, the output-side rotation transmission member 154b, the rotating shaft 154s, and the third stage input-side rotation transmission member 155a rotate. Further in conjunction with this, the third stage annular member 155c, the output-side rotation transmission member 155b, and the shaft 126a of the second joint 126 rotate. As a result, the second arm 122 rotates.

[0080] Thus, the second drive unit 150 includes a wrap-around reduction gear having an output-side rotation transmission member 155b as a second output-side rotation transmission member, an input-side rotation transmission member 155a as a second input-side rotation transmission member, and an annular member 155c as a second annular member wrapped around the output-side rotation transmission member 155b and the input-side rotation transmission member 155a. This makes it possible to reduce the weight of the robot arm 200 (especially the first arm 121) and reduce the cost of the robot 10. As the robot arm 200 becomes lighter, the inertial force when rotating the first arm 121 and other components of the robot arm 200 is reduced, so that the rotation of the first arm 121 and other components can be performed at a higher speed, thereby improving work efficiency by increasing the work speed.

[0081] Similarly, the third power transmission unit 162 includes a reduction gear that reduces and transmits the rotational speed of the third motor 161. In this embodiment, the reduction gear is composed of a multi-stage reduction type winding transmission device, more specifically a multi-stage reduction type pulley-belt mechanism.

[0082] Specifically, as shown in Figure 7, the third power transmission unit 162, as a reduction gear, includes an input-side rotational transmission member 163a provided on the third output shaft 161a of the third motor 161, a first-stage rotating shaft 163s spaced apart from the third output shaft 161a, an output-side rotational transmission member 163b provided on the first-stage rotating shaft 163s, and an annular member 163c wrapped around the input-side rotational transmission member 163a and the output-side rotational transmission member 163b. Hereinafter, these will also be referred to as the "first-stage reduction gear".

[0083] Furthermore, the third power transmission unit 162, as a reduction gear, includes an input-side rotational transmission member 164a provided on the first-stage rotating shaft 163s, a second-stage rotating shaft 164s spaced apart from the first-stage rotating shaft 163s, an output-side rotational transmission member 164b provided on the second-stage rotating shaft 164s, and an annular member 164c wrapped around the input-side rotational transmission member 164a and the output-side rotational transmission member 164b. Hereinafter, these will also be referred to as the "second-stage reduction gear".

[0084] Furthermore, the third power transmission unit 162, as a reduction gear, includes an input-side rotational transmission member 165a provided on the second-stage rotating shaft 164s, an output-side rotational transmission member 165b (third output-side rotational transmission member) provided on the shaft 126a of the second joint 126 via a bearing portion 166, and an annular member 165c wrapped around the input-side rotational transmission member 165a and the output-side rotational transmission member 165b. Hereinafter, these will also be referred to as the "third-stage reduction gear". As shown in Figure 8, the output-side rotational transmission member 165b is provided between a plate-shaped link 131a and a side plate portion 121d.

[0085] As shown in Figure 8, in this embodiment, the bearing portion 166 is composed of two bearings 166a (first bearing). The outer ring of each bearing 166a is fixed to the inner circumferential surface of the output-side rotation transmission member 165b, and the inner ring of each bearing 166a is fixed to the outer circumferential surface of the small-diameter portion of the shaft 126a of the second joint 126, for example, by press-fitting. The x-axis-side end face of the inner ring of the bearing 166a closer to the first shaft A1 of the two bearings 166a abuts against the stepped portion 126k.

[0086] Furthermore, link 131a is fixed to the side surface of output-side rotation transmission member 165b. As a result, link 131a rotates in conjunction with the third drive unit 160, independently of the rotation of shaft 126a of the second joint 126.

[0087] As shown in Figure 7, when viewed from the second direction D2, the first stage rotation shaft 163s is located above the third output shaft 161a (towards the + side of the z-axis) and towards the third direction D3-, and is situated on the first axis A1. Similarly, the second stage rotation shaft 164s is located above the first stage rotation shaft 163s and is situated on the first axis A1. Therefore, the first stage rotation shaft 163s, the second stage rotation shaft 164s, and the second axis A2 are aligned in the first direction D1, and when viewed from the second direction D2, they are all located on the first axis A1.

[0088] As shown in Figure 8, a bearing portion 163t is provided at the end of the first stage rotating shaft 163s on the second direction D2+ side, which rotatably holds the first stage rotating shaft 163s. The bearing portion 163t is attached to the side plate portion 121d. On the first stage rotating shaft 163s, the first stage output side rotation transmission member 163b and the second stage input side rotation transmission member 164a are provided in order toward the second direction D2- side, spaced apart from each other.

[0089] Similarly, the end of the second stage rotating shaft 164s on the second direction D2+ side is provided with a bearing portion 164t that rotatably holds the rotating shaft 164s. The bearing portion 164t is attached to the side plate portion 121d. On the second stage rotating shaft 164s, the third stage input-side rotation transmission member 165a and the second stage output-side rotation transmission member 164b are provided in order toward the second direction D2- side, spaced apart from each other.

[0090] The input-side rotational transmission members 163a, 164a, 165a, output-side rotational transmission members 163b, 164b, 165b, and annular members 163c, 164c, 165c that constitute the third power transmission section 162 are all positioned between the pair of side plate portions 121c, 121d of the first arm 121. In other words, they are housed in the arm base 121a of the first arm 121. However, some of them may protrude outside the arm base 121a.

[0091] As a result, when the third output shaft 161a rotates due to the drive of the third motor 161, the first stage input-side rotation transmission member 163a rotates in conjunction with it. In conjunction with this, the first stage annular member 163c, the output-side rotation transmission member 163b, the first stage rotating shaft 163s, and the second stage input-side rotation transmission member 164a rotate. Further in conjunction with this, the second stage annular member 164c, the output-side rotation transmission member 164b, the rotating shaft 164s, and the third stage input-side rotation transmission member 165a rotate. Further in conjunction with this, the third stage annular member 165c and the output-side rotation transmission member 165b rotate. As a result, the link 131a of the link mechanism 131 rotates.

[0092] Thus, both the second power transmission unit 152 and the third power transmission unit 162 are configured with a three-stage reduction pulley-belt mechanism. In this embodiment, the second power transmission unit 152 and the third power transmission unit 162 use the same type of input-side rotational transmission member (small diameter pulley), output-side rotational transmission member (large diameter pulley), and annular member (belt) coaxial bearing, which are located in the same stage.

[0093] In other words, the input-side rotational transmission members (small-diameter pulleys) located on the same stage in the second power transmission unit 152 and the third power transmission unit 162 are identical in terms of pulley type (such as V-pulleys and toothed pulleys), dimensions (such as diameter and width), and material. Similarly, the output-side rotational transmission members (large-diameter pulleys) located on the same stage in the second power transmission unit 152 and the third power transmission unit 162 are identical in terms of pulley type (such as V-groove belts and toothed belts (cogged belts)), dimensions (such as width, thickness, and circumference), and material. During manufacturing, the number of parts required to produce the robot 10 can be reduced, allowing for efficient production of the robot 10. As a result, the productivity of the robot 10 is improved. Furthermore, during use, the number of parts that need to be prepared for replacement of deteriorated or faulty parts can be reduced, thus simplifying the maintenance of the robot 10. In addition, from the viewpoint of suppressing slippage of the annular member (belt) relative to the rotational transmission member and transmitting greater torque, it is preferable that the small-diameter pulley and large-diameter pulley are toothed pulleys, and the belt is a toothed belt.

[0094] Furthermore, the reduction ratios of the second power transmission unit 152 and the third power transmission unit 162 are not particularly limited, depending on the output torque of the second motor 151 and the third motor 161, but are preferably 1.5 or more and 20 or less, and more preferably 2 or more and 10 or less. This allows the second power transmission unit 152 to generate sufficient torque to rotate the second arm 122 while the fourth arm 124 is holding the workpiece, while also enabling the rotational speed of the second arm 122 to be appropriate.

[0095] Furthermore, if such a reduction ratio is to be obtained in a single stage, the diameters of the output-side rotation transmission members 153b and 163b of the first stage must be increased accordingly, and the width of the base end of the robot arm 200 in the third direction D3 increases accordingly. On the other hand, as the number of stages in the reduction gear increases, the number of reduction units arranged between the second motor 151 and the second joint 126 increases, and the dimension of the first arm 121 in the first direction D1 increases. The larger the dimension of the first arm 121 in the first direction, the further the lowest reachable position of the end effector E1 is from the mounting surface of the robot 10. Therefore, it is preferable that the reduction gears of the second power transmission unit 152 and the third power transmission unit 162 have two to five stages, and more preferably two to four stages.

[0096] If the gearbox has three stages, the reduction ratio of the first stage is preferably 1.1 or more and 5 or less, the reduction ratio of the second stage is preferably 1.1 or more and 5 or less, and the reduction ratio of the third stage is preferably 1.2 or more and 5 or less.

[0097] Next, the positional relationship between the second power transmission unit 152 and the third power transmission unit 162 will be explained. As shown in Figures 6 and 7, the positions of the rotating shafts in the third direction D3 are the same for both the second power transmission unit 152 and the third power transmission unit 162, as they are located on the same stage.

[0098] Therefore, as shown in Figure 5, when viewed from the first direction D1, the external shape of the second power transmission unit 152 coincides with the external shape of the third power transmission unit 162 when rotated 180 degrees around the first axis A1 as the central axis. In other words, the second power transmission unit 152 and the third power transmission unit 162 are point-symmetric with respect to the first axis A1 when viewed from the first direction D1. As a result, the weight balance of the base end of the robot arm 200 can be improved.

[0099] Furthermore, as shown in Figure 8, the positions (heights) of the rotating shafts in the second power transmission unit 152 and the third power transmission unit 162, which are located on the same stage, are the same in the first direction D1. Moreover, when viewed from the third direction D3, the outer shape of the second power transmission unit 152 matches the outer shape of the third power transmission unit 162 when the first axis A1 is inverted with respect to the central axis. In other words, the second power transmission unit 152 and the third power transmission unit 162 are symmetrical with respect to the first axis A1 when viewed from the third direction D3. Therefore, the weight balance of the base end of the robot arm 200 can be improved.

[0100] As described above, the second power transmission unit 152 and the third power transmission unit 162 are rotationally symmetric with respect to the first axis A1. As previously mentioned, the pair of side plate units 121c and 121d are also rotationally symmetric with respect to the first axis A1. Therefore, the same assembly can be used for the assembly composed of one side plate unit 121c and the second power transmission unit 152, and for the assembly composed of the other side plate unit 121d and the third power transmission unit 162. As a result, the number of assemblies to be prepared for manufacturing the robot 10 can be reduced, and the robot 10 can be manufactured efficiently.

[0101] The configurations of the second power transmission unit 152 and the third power transmission unit 162 are not limited to those described above. For example, the reduction gear may be other winding transmission devices such as a sprocket-chain mechanism or a wheel-wire mechanism, or a gear device such as a planetary gear or a harmonic drive gear. The reduction gear may also be a single-stage reduction gear. The reduction gear may also be a continuously variable transmission (CVT). Furthermore, the second power transmission unit 152 and the third power transmission unit 162 may not include a reduction gear and may transmit the power output by the second motor 151 and the third motor 161 without reduction. In addition, the type, type, performance, dimensions, etc., of corresponding components in the second power transmission unit 152 and the third power transmission unit 162 may differ.

[0102] Furthermore, in the robot 10, the first-stage bearings 153t, 163t and the second-stage bearings 154t, 164t may each be slidably provided with respect to the arm base 121a of the first arm 121 in the first direction D1. This allows for adjustment of the distance between the second output shaft 151a and the first-stage rotating shaft 153s, the distance between the first-stage rotating shaft 153s and the second-stage rotating shaft 154s, and the distance between the second-stage rotating shaft 154s and the shaft 126a of the second joint 126. Similarly, the distance between the third output shaft 161a and the first-stage rotating shaft 163s, the distance between the first-stage rotating shaft 163s and the second-stage rotating shaft 164s, and the distance between the second-stage rotating shaft 164s and the shaft 126a of the second joint 126 can be adjusted. As a result, the tension applied to the annular members 153c, 154c, 155c, 163c, 164c, and 165c can be adjusted to the optimal tension. Furthermore, the same assembly may be used for both the assembly composed of one side plate 121c and the second power transmission unit 152, and the assembly composed of the other side plate 121d and the third power transmission unit 162, including this adjustment mechanism.

[0103] Next, the positional relationship between the second motor 151 and the third motor 161 and the second power transmission unit 152 and the third power transmission unit 162 will be explained. As mentioned above, the second output shaft 151a and the third output shaft 161a protrude in opposite directions in the second direction D2. Therefore, it is possible to prevent the second power transmission unit 152 and the third power transmission unit from being positioned biased to one side of the second direction D2. If the second power transmission unit 152 and the third power transmission unit 162 are positioned biased to one side of the second direction D2, then in order to prevent interference between the second power transmission unit 152 and the third power transmission unit 162, it is necessary to separate the second power transmission unit 152 and the third power transmission unit 162 in the third direction D3. Therefore, by having the second output shaft 151a and the third output shaft 161a protrude in opposite directions in the second direction D2, the second power transmission unit 152 and the third power transmission unit 162 can be arranged to be compact in the third direction D3.

[0104] Furthermore, as shown in Figure 9, the plane passing through the center of the second output shaft 151a of the second motor 151 and parallel to the first direction D1 and the second direction D2 (a plane parallel to the x-z plane) is defined as the "first plane P11". Also, the plane passing through the center of the third output shaft 161a of the third motor 161 and parallel to the first plane P11 is defined as the "second plane P12". The first stage rotating shaft 153s and the second stage rotating shaft 154s of the second power transmission unit 152 are located between the first plane P11 and the second plane P12.

[0105] As mentioned above, the positions of the rotating shafts in the same stage of the second power transmission unit 152 and the third power transmission unit 162 are the same in the third direction D3. Therefore, the first stage rotating shaft 163s and the second stage rotating shaft 164s of the third power transmission unit 162 are also located between the first plane P11 and the second plane P12.

[0106] As a result, the base end of the robot arm 200 can be miniaturized in the third direction D3 compared to the case where each rotation axis 153s, 154s, 163s, and 164s is located outside the space between the first plane P11 and the second plane P12. Therefore, the degree of freedom in installing the robot 10 can be increased. Also, as shown in Figure 10, by miniaturizing the first arm 121 in the third direction D3, the range of motion of the fourth arm 124 on the third direction D3 side can be increased. This allows the range of movement of the end effector E1 to be increased.

[0107] Furthermore, as shown in Figure 8, the second arm 122 and the link 131a of the link mechanism 131 are located above the output-side rotation transmission members 154b and 164b of the second-stage reduction unit. Therefore, as shown in Figure 9, the range of motion of the second arm 122 and the link 131a is set to a range that does not interfere with the output-side rotation transmission members 154b and 164b of the second-stage reduction unit. The further the rotation axes 154s and 164s of the second-stage reduction unit are from the boundary surface P1 in the third direction D3, the narrower the range of motion of the second arm 122 and the link 131a becomes. Therefore, by positioning the rotation axes 154s and 164s of the second stage between the first plane P11 and the second plane P12, the range of motion of the second arm 122 and the link 131a can be widened compared to the case where the rotation axes 154s and 164s of the second stage are positioned outside the space between the first plane P11 and the second plane P12.

[0108] In particular, in this embodiment, the second output shaft 151a and the third output shaft 161a are separated in the third direction D3, while the positions of the rotating shafts 153s and 154s in the second power transmission unit 152 and the third power transmission unit 162 are the same in the third direction D3, and both are arranged on the interface surface P1. This makes it possible to miniaturize the base end of the robot arm 200 in the second direction D2 while expanding the range of motion of the second arm 122 and the link 131a.

[0109] Although the robot 10 has been described above, its configuration is not limited to that described above. For example, the first arm 121 does not need to rotate relative to the base 110. In this case, the robot 10 does not need to be provided with a base 110.

[0110] As mentioned above, the second arm 122 is fixed to one end of the shaft 126a shown in Figure 8 (the end on the x-axis - side) via the output side rotation transmission member 155b. The other end of the shaft 126a (the end on the x-axis + side) supports the output side rotation transmission member 165b via two bearings 166a (first bearing).

[0111] Therefore, when the shaft 126a rotates due to the operation of the second drive unit 150, the second arm 122 rotates together with the shaft 126a, but the rotational force of the shaft 126a is not transmitted to the output-side rotation transmission member 165b, and thus does not affect the operation of the link mechanism 131. The reason why the rotational force of the shaft 126a is not transmitted to the output-side rotation transmission member 165b is that only the inner rings of the two bearings 166a rotate together with the shaft 126a, and the outer rings do not rotate together with the inner rings.

[0112] On the other hand, when the shaft 126a is not rotating, that is, when the second drive unit 150 is not operating, if the third drive unit 160 is activated, the output-side rotation transmission member 165b rotates around the second shaft A2. In this case, only the outer rings of the two bearings 166a rotate together with the output-side rotation transmission member 165b, and the inner rings do not rotate, so the rotational force of the third drive unit 160 is not transmitted to the shaft 126a.

[0113] Furthermore, even when both the second drive unit 150 and the third drive unit 160 are operating, they can operate independently using the same principle as described above.

[0114] As described above, the presence of the shaft 126a allows the output-side rotation transmission member 155b to rotate stably together with the shaft 126a, and the output-side rotation transmission member 165b to rotate stably supported by the shaft 126a. Therefore, the second axis A2, which is the central axis of the output-side rotation transmission member 155b, and the second axis A2, which is the central axis of the output-side rotation transmission member 165b, coincide. As a result, even if vibration is generated by the operation of the robot arm 200, the central axis of the output-side rotation transmission member 155b and the central axis of the output-side rotation transmission member 165b can each maintain a state of coincidence with the second axis A2 without axial misalignment, and thus the output-side rotation transmission member 155b and the output-side rotation transmission member 165b can rotate stably. Consequently, the positional accuracy of the robot arm 200's movement, in particular the positional accuracy of the tip of the robot arm 200, can be improved, and the work accuracy of the robot 10 can be improved.

[0115] The central axis of the output-side rotation transmission member 155b and the central axis of the output-side rotation transmission member 165b may be slightly offset from each other. Even in this case, because the shaft 126a is provided in the above-described installation structure, the output-side rotation transmission member 155b and the output-side rotation transmission member 165b can rotate stably, and the above-mentioned effects can be obtained.

[0116] Thus, the robot 10 includes a first arm 121 installed along a first axis A1, a second arm 122 rotatably connected to the first arm 121 around a second axis A2 that is not parallel to the first axis A1, a third arm 123 rotatably connected to the second arm 122 around a third axis A3 that is parallel to the second axis A2, a link mechanism 131 that transmits power to rotate the third arm 123 to the third arm 123, a second drive unit 150 installed on the first arm 121 that rotates the second arm 122, and a third drive unit 160 installed on the first arm 121 that rotates the third arm 123. The second drive unit 150 includes a second motor 151, an output-side rotation transmission member 155b fixed to the second arm 122 and acting as a second output-side rotation transmission member that transmits power from the second motor 151 to the second arm 122, and a shaft 126a fixed to the output-side rotation transmission member 155b and acting as a second shaft that rotates together with the output-side rotation transmission member 155b around the second axis A2. The third drive unit 160 includes a third motor 161, an output-side rotation transmission member 165b fixed to a link 131a of the link mechanism 130 and acting as a third output-side rotation transmission member that transmits power from the third motor 161 to the link mechanism 130, and a bearing 166a acting as a first bearing that rotatably supports the output-side rotation transmission member 165b with respect to the shaft 126a. As a result, the output-side rotation transmission member 155b can rotate stably together with the shaft 126a, and the output-side rotation transmission member 165b can rotate stably while being supported by the shaft 126a. That is, since the second axis A2, which is the central axis of the output-side rotation transmission member 155b, and the second axis A2, which is the central axis of the output-side rotation transmission member 165b, coincide, no axial misalignment occurs. As a result, the output-side rotation transmission member 155b and the output-side rotation transmission member 165b can rotate stably. Therefore, the positional accuracy of the robot arm 200's movement, in particular, the positional accuracy of the tip of the robot arm 200, can be improved. Consequently, the work accuracy of the robot 10 can be improved.

[0117] As mentioned above, the shaft 126a is rotatably supported at one end (the x-axis negative end) by a bearing 126d, and at the other end (the x-axis positive end) by a bearing 126e. Also, as shown in Figure 8, when viewed from the third direction D3- (y-axis negative side), the bearing 126d, output-side rotation transmission member 155b, output-side rotation transmission member 165b, and bearing 126e are arranged in that order from the x-axis negative side to the x-axis positive side.

[0118] With this configuration, the shaft 126a is supported by the first arm 121 at two relatively distant points (bearings 126d and 126e) in the direction of the first axis A (x-axis direction). As a result, the shaft 126a rotates while being supported by the first arm 121 with greater stability. Therefore, the positional accuracy of the tip of the robot arm 200 can be improved more effectively.

[0119] Thus, the robot 10 is equipped with bearing portions 126b and 126c at one end and the other end of the second shaft, the shaft 126a, respectively, which serve as second bearings that rotatably support the shaft 126a. Between bearings 126d and 126e, an output-side rotation transmission member 155b, which serves as a second output-side rotation transmission member, and an output-side rotation transmission member 165b, which serves as a third output-side rotation transmission member, are installed. As a result, the shaft 126a can rotate more stably, and the positional accuracy of the tip of the robot arm 200 can be improved more effectively.

[0120] Note that the arrangement positions of the bearing 126d, output-side rotation transmission member 155b, output-side rotation transmission member 165b, and bearing 126e are not limited to the above configuration. For example, as shown in Figure 8, when viewed from the third direction D3-side (y-axis-side), the output-side rotation transmission member 155b, bearing 126d, bearing 126e, and output-side rotation transmission member 165b may be arranged in that order from the x-axis-side.

[0121] As described above, the first arm 121 has an arm base 121a that houses the second drive unit 150 and the third drive unit 160, and the second shaft, shaft 126a, is rotatably mounted on the arm base 121a via bearing portions 126b and 126c, which serve as second bearings. As a result, the second bearing portion and the shaft 126a are stably supported by the relatively rigid arm base 121a, allowing the shaft 126a to rotate even more stably. Therefore, the positional accuracy of the tip of the robot arm 200 can be further improved.

[0122] The type and structure of bearings 166a, 126d, and 126e are not particularly limited, but in this embodiment, they are all deep groove ball bearings. Deep groove ball bearings have relatively deep grooves formed in the inner and outer rings, and the contact area between the balls positioned between the inner and outer rings and the inner and outer rings is relatively large. For this reason, they have excellent durability and operational stability against both axial loads (loads along the second shaft A2) and radial loads (loads in the radial direction of the shaft 126a). In other words, even if relatively large axial loads and relatively large radial loads are applied to bearings 166a, 126d, and 126e, they can operate stably.

[0123] In particular, since a relatively large radial load is applied to the bearing 166a from the output-side rotational transmission member 165b, it is advantageous to use a deep groove ball bearing as the bearing 166a.

[0124] Furthermore, bearings 126d and 126e are subjected to relatively large radial loads when the second arm 122 and the third arm 123 are in motion. In addition, bearings 126d and 126e are subjected to relatively large axial loads as the first arm rotates. For this reason, it is advantageous to use deep groove ball bearings as bearings 126d and 126e.

[0125] Thus, the second bearings, bearings 126d and 126e, are deep groove ball bearings. As a result, even if relatively large axial loads and relatively large radial loads are applied to bearings 126d and 126e, they can operate stably.

[0126] Furthermore, at least one of the bearings 126d and 126e may be a bearing other than a deep groove ball bearing, for example, an angular contact ball bearing. Also, the bearing 166a may be a bearing other than a deep groove ball bearing, for example, an angular contact ball bearing.

[0127] The robot 10 has a second encoder E2 (see Figures 3, 5, and 8) that detects the amount of rotation of the second arm 122 (information related to rotation such as rotation direction, rotation speed, and rotation angle), and a third encoder E3 (see Figure 2) that detects the amount of rotation of the third arm 123. The second encoder E2 and the third encoder E3 are both rotary encoders and are composed of magnetic encoders.

[0128] The second encoder E2 is installed on or around the shaft 126a (hereinafter collectively referred to as "installed on the shaft 126a"). More specifically, the second encoder E2 has a disc-shaped scale, a magnetic sensor, and a signal processing unit. The disc-shaped scale is installed at the other end of the shaft 126a (the end on the x-axis + side), and the magnetic sensor and signal processing unit are installed on the bearing holder 126t of the bearing portion 126c. This allows the magnetic sensor to detect the amount of rotation of the scale that rotates together with the shaft 126a. In particular, as mentioned above, the shaft 126a can rotate stably, so the amount of rotation of the shaft 126a, and consequently the amount of rotation of the second arm 122 that rotates together with the shaft 126a, can be accurately detected.

[0129] The third joint 127 has a shaft 127a provided along the third axis A3. The shaft 127a is sometimes referred to as the "third shaft". The third encoder E3 is installed on or around the shaft 127a. (Hereinafter, these will be collectively referred to as "installed on the shaft 127a".) More specifically, the third encoder E3 has a disc-shaped scale, a magnetic sensor and a signal processing unit, the disc-shaped scale is installed at one end of the shaft 127a (the -X axis side), and the magnetic sensor and signal processing unit are installed on the third arm 123. As a result, the magnetic sensor, which rotates with the third arm 123, can detect the amount of rotation of the third arm 123 relative to the shaft 127a. In particular, as mentioned above, since the third arm 123 can rotate stably, the amount of rotation of the third arm 123 relative to the shaft 127a and, consequently, the amount of rotation of the third arm 123 relative to the second arm 122 can be accurately detected. The third encoder E3 may be installed on or around the pivot 131c of the link mechanism 131.

[0130] Although not shown in the diagram, the robot 10 includes a first encoder for detecting the amount of rotation of the first arm 121 and a fourth encoder for detecting the amount of rotation of the fourth arm 124. The first encoder is connected to the motor that drives the first arm 121, and the fourth encoder is connected to the motor that drives the fourth arm 124.

[0131] The second encoder E2 and the third encoder E3 are electrically connected to the control device 20. The detected values ​​of the second encoder E2 and the third encoder E3 are received by the communication unit 203 of the control device 20 and input to the calculation unit 201 of the control device 20 in real time or at a predetermined timing, and predetermined processing is performed.

[0132] The control device 20 can acquire information about the rotation of the second arm 122, such as the rotational direction, rotational speed, and rotational angle, based on the detected value of the second encoder E2. Similarly, the control device 20 can acquire information about the rotation of the third arm 123, such as the rotational direction, rotational speed, and rotational angle of the third arm 123 relative to the second arm 122, based on the detected value of the third encoder E3. This information is stored in the storage unit 202 of the control device 20 shown in Figure 1.

[0133] The control device 20 drives the second arm 122 and the third arm 123 to correct their rotation amounts based on the acquired rotation amounts of the second arm 122 (information related to rotation) and the third arm 123 (information related to rotation). In particular, it can perform feedback control on the power supply to the second motor 151 that drives the second arm 122 and the third motor 161 that drives the third arm 123. This allows the second arm 122 and the third arm 123 to be driven more appropriately, contributing to an improvement in the positional accuracy of the tip of the robot arm 200.

[0134] For example, a display unit (not shown), such as a liquid crystal monitor, is provided on the casing of the base 110 or the outer surface of the control device 20. Information regarding rotation detected by the second encoder E2 and the third encoder E3 can be displayed on the display unit at a predetermined timing (as needed). Examples of the display format and method on the display unit include numbers, characters, symbols, graphs, two-dimensional images, three-dimensional images, etc., or a combination of two or more of these.

[0135] Thus, the robot 10 is equipped with a second encoder E2 for detecting the amount of rotation of the second arm 122, and the second encoder E2 is installed on the second shaft, which is the shaft 126a. As mentioned above, since the shaft 126a can rotate stably, the amount of rotation of the shaft 126a, and by extension the amount of rotation of the second arm 122 which rotates together with the shaft 126a, can be accurately detected.

[0136] As mentioned above, the detected amount of rotation of the second arm 122 can be used to correct the drive of the second arm 122 to be more appropriate, thereby further improving the positional accuracy of the tip of the robot arm 200.

[0137] Furthermore, the robot 10 is equipped with a third encoder for detecting the amount of rotation of the third arm 123. The third encoder E3 is installed on the shaft 127a, which is a third shaft that rotates around the third axis A3 to which the third arm 123 is attached. This allows the magnetic sensor to detect the amount of rotation of the shaft 127a. Thus, the amount of rotation of the third link mechanism 130, and consequently the amount of rotation of the third arm 123, can be accurately detected.

[0138] As mentioned above, the detected rotation amount of the third arm 123 can be used to correct the drive of the third arm 123 to be more appropriate, thereby further improving the positional accuracy of the tip of the robot arm 200.

[0139] The second encoder E2 and the third encoder E3 may be encoders other than magnetic encoders, such as optical encoders or capacitive encoders.

[0140] Furthermore, the installation positions of the second encoder E2 and the third encoder E3 are not limited to those described above, as long as they are in positions where the amount of rotation of each arm can be detected.

[0141] <Second Embodiment> Figure 11 is a cross-sectional view of the second joint of a robot according to the second embodiment of the present invention.

[0142] The following description of the second embodiment of the robot of the present invention will be made with reference to Figure 11, focusing on the differences from the first embodiment, and omitting explanations of similar matters.

[0143] As shown in Figure 11, the shaft 126a has stepped portions 126j and 126k. When viewed in the direction of the second axis A2, the portion of the shaft 126a between the stepped portions 126j and 126k has a larger outer diameter than the portion of the shaft 126a on the x-axis negative side of the stepped portion 126j and the portion on the x-axis positive side of the stepped portion 126k.

[0144] The inner ring of bearing 126d abuts against the stepped portion 126j, restricting bearing 126d from moving further towards the x-axis + side. The inner ring of bearing 166a abuts against the stepped portion 126k, restricting bearing 166a from moving further towards the x-axis - side.

[0145] Furthermore, in this embodiment, two bearings 126d are provided. The bearings 126d are composed of angular contact ball bearings. Angular contact ball bearings have excellent durability and operational stability against both axial loads (loads along the second axis A2) and radial loads (loads in the radial direction of the shaft 126a). For this reason, it is advantageous to use angular contact ball bearings as bearings 126d, which are prone to relatively large axial and radial loads.

[0146] Furthermore, the angular contact ball bearing exhibits superior durability and operational stability against loads from only one direction along the second axis A2. Therefore, both bearings 126d are arranged side by side facing opposite directions. This allows for superior durability and operational stability against loads from both directions along the second axis A2. Note that the bearings 126d may also be deep groove ball bearings.

[0147] As shown in Figure 11, the robot 10 includes a pressurizing member 126f, a pressurizing member 126g, a pressurizing member 126h, and a spacer 126i. The pressurizing members 126f, 126g, 126h, and spacer 126i are all ring-shaped and can be inserted onto the shaft 126a.

[0148] The preloading member 126f applies preload to the inner rings of both bearings 126d simultaneously. The preloading member 126f consists of a male threaded portion (not shown) formed on the outer circumference of the shaft 126a and a nut with a female thread formed on the inner circumference that engages with it. By rotating the preloading member 126f in a predetermined direction, the inner rings of both bearings 126d can be pressed toward the stepped portion 126j. As a result, the preloading member 126f can apply preload to the bearings 126d in the axial direction (x-axis + direction) of the second shaft A2. Therefore, both bearings 126d can operate more stably.

[0149] The preloading member 126g applies preload to the inner ring of the bearing 126e. The preloading member 126g consists of a male threaded portion (not shown) formed on the outer circumference of the shaft 126a and a nut with a female thread formed on its inner circumference that engages with it. By rotating the preloading member 126g in a predetermined direction, the inner ring of the bearing 126e can be pressed toward the x-axis side end of the bearing holder 126t. As a result, the preloading member 126g can apply preload to the bearing 126e in the axial direction (x-axis direction) of the second shaft A2. Therefore, the bearing 126e can operate more stably.

[0150] The preloading member 126h applies preload to the inner rings of both bearings 166a simultaneously. Each bearing 166a consists of a male threaded portion (not shown) formed on the outer circumference of the shaft 126a and a nut with a female thread formed on its inner circumference that engages with it. By rotating the preloading member 126h in a predetermined direction, the inner rings of both bearings 166a can be pressed toward the stepped portion 126k. A ring-shaped spacer 126i is provided between the two bearings 166a, and both bearings 166a are in contact with the spacer 126i. With this configuration, the preloading member 126h can apply preload to both bearings 166a in the axial direction (x-axis direction) of the second shaft A2. Therefore, both bearings 166a can operate more stably.

[0151] Thus, the robot 10 is equipped with a preloading member 126f that applies preload in the axial direction of the second shaft A2 to either the inner or outer ring (in the illustrated configuration, the inner ring) of the bearing 126d, which serves as the second bearing. As a result, the preloading member 126f can apply preload to the bearing 126d in the axial direction of the second shaft A2. Therefore, both bearings 126d can operate more stably. Consequently, misalignment, wobbling, rattling, etc., can be prevented, and the bearing 126d can be held stably. Therefore, axial wobble during rotation of the shaft 126a can be prevented, and the positional accuracy of the tip of the robot arm 200 can be more effectively improved.

[0152] However, the configuration is not limited to the above, and the pre-pressurizing member 126f may be configured to apply pre-pressurization to the outer ring of the bearing 126d.

[0153] Although the robot of the present invention has been described in the illustrated embodiments above, the present invention is not limited to these embodiments. Furthermore, each part of the robot can be replaced with any structure capable of performing similar functions. In addition, any structure may be added to the robot.

[0154] 1...Robot system, 10...Robot, 20...Control device, 110...Base, 121...First arm, 121a...Arm base, 121b...Bottom plate, 121c...Side plate, 121d...Side plate, 121e...Link support member, 121f...Main body, 121g...Protruding part, 122...Second arm, 123...Third arm, 124...Fourth arm, 124...Arm, 125...First joint, 126...Second joint, 126a...Shaft, 126b...Bearing part, 126c...Bearing part, 126d...Bearing, 126e...Bearing, 126f...Pressurizing member, 126g...Pressurizing member, 126h...Pressurizing member, 12 6j...Stepped section, 126k...Stepped section, 126s...Bearing holder, 126t...Bearing holder, 127...Third joint, 127a...Shaft, 128...Fourth joint, 130...Link mechanism, 131...Link mechanism, 131a...Link, 131b...Link, 131c...Pivot, 131d...Pivot, 131h...Through hole, 132...Link mechanism, 132a...Link, 132b...Link, 132c...Link, 132d...Pivot, 132e...Pivot, 132f...Pivot, 132g...Pivot, 140...First drive unit, 150...Second drive unit, 151...Second motor , 151a...Second output shaft, 151b...Second housing, 151c...Mount, 152...Second power transmission unit, 153a...Input side rotation transmission member, 153b...Output side rotation transmission member, 153c...Annular member, 153s...Rotating shaft, 153t...Bearing part, 154a...Input side rotation transmission member, 154b...Output side rotation transmission member, 154c...Annular member, 154s...Rotating shaft, 154t...Bearing part, 155a...Input side rotation transmission member, 155b...Output side rotation transmission member, 155c...Annular member, 160...Third drive unit, 161...Third motor, 161a...Third output shaft, 161b...Third housing Ring, 161c...mount, 162...third power transmission unit, 163a...input side rotation transmission member, 163b...output side rotation transmission member, 163c...annular member, 163s...rotating shaft, 163t...bearing part, 164a...input side rotation transmission member, 164b...output side rotation transmission member, 164c...annular member, 164s...rotating shaft, 164t...bearing part, 165a...input side rotation transmission member, 165b...output side rotation transmission member, 165c...annular member, 166...bearing part, 166a...bearing, 170...fourth drive unit, 200...robot arm, 201...calculation unit, 202...storage unit, 203...communication unit,A1...First axis, A2...Second axis, A3...Third axis, A4...Fourth axis, A5...Fifth axis, D1...First direction, D2...Second direction, D3...Third direction, E1...End effector, E2...Second encoder, E3...Third encoder, P1...Boundary surface, P11...First plane, P12...Second plane,

Claims

1. A first arm installed along a first axis; a second arm rotatably connected to the first arm around a second axis not parallel to the first axis; a third arm rotatably connected to the second arm around a third axis parallel to the second axis; a link mechanism for transmitting power to rotate the third arm to the third arm; a second drive unit installed on the first arm for rotationally driving the second arm; and a third drive unit installed on the first arm for rotationally driving the third arm, wherein the second drive unit comprises a second motor; a second output-side rotational transmission member fixed to the second arm for transmitting power from the second motor to the second arm; and a second shaft fixed to the second output-side rotational transmission member and rotating together with the second output-side rotational transmission member around the second axis. The robot is characterized in that the third drive unit comprises a third motor, a third output-side rotational transmission member fixed to a link of the link mechanism and transmitting power from the third motor to the link mechanism, and a first bearing that rotatably supports the third output-side rotational transmission member with respect to the second shaft.

2. The robot according to claim 1, wherein the second shaft is provided with second bearings at one end and the other end, respectively, which rotatably support the second shaft, and the second output side rotation transmission member and the third output side rotation transmission member are installed between the two second bearings.

3. The robot according to claim 2, wherein the first arm has an arm base that houses the second drive unit and the third drive unit, and the second shaft is rotatably mounted on the arm base via the second bearing.

4. The robot according to claim 2 or 3, wherein the second bearing is a deep groove ball bearing.

5. The robot according to claim 2 or 3, further comprising a preloading member that applies preload in the axial direction of the second shaft to either the inner ring or the outer ring of the second bearing.

6. The robot according to claim 1 or 2, wherein the second drive unit comprises a wrap-around reduction gear having a second output side rotation transmission member, a second input side rotation transmission member, and a second annular member wrapped around the second output side rotation transmission member and the second input side rotation transmission member.

7. The robot according to claim 1 or 2, further comprising a second encoder for detecting the amount of rotation of the second arm, wherein the second encoder is installed on the second shaft.

8. The robot according to claim 1 or 2, further comprising a third encoder for detecting the amount of rotation of the third arm, wherein the third encoder is installed on a third shaft that rotates around the third axis to which the third arm is attached.

Images