robot

Abstract

We provide a robot that can reduce the width of the robot. [Solution] A robot comprising: a first arm installed along a first axis; a second arm rotatably connected to the first arm around a second axis; a third arm rotatably connected to the second arm around a third axis; a second drive unit having a second motor and installed on the first arm; and a third drive unit having a third motor and installed on the first arm, wherein the second motor and the third motor are spaced apart in a first direction along the second axis and the first axis; the second motor and the third motor are positioned opposite each other in a third direction perpendicular to the first direction and the second direction along the second axis; and the second output shaft of the second motor and the third output shaft of the third motor extend in the second direction and protrude in opposite directions from each other.

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[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 performed manually is being attempted.

[0003] For example, Patent Document 1 below discloses a robot having a robotic arm in which motors and speed reducers for rotationally driving a first arm and motors and speed reducers for rotationally driving a second arm are arranged on the rotation axis of the first arm.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in such a robot, since two sets of motors and speed reducers are located on the same straight line, the width of the robotic arm becomes relatively large. Therefore, there is a problem that the degree of freedom when installing the robot, such as installing the robot in consideration of the width of the robotic arm so that the robotic arm does not interfere with surrounding objects, is reduced.

Means for Solving the Problems

[0006] The robot according to an application example of the present invention includes a first arm installed along a first axis, a second arm rotatably connected to the first arm about a second axis that is non-parallel to the first axis, A third arm is connected to the second arm so as to be rotatable around a third axis parallel to the second axis, A link mechanism that transmits power to rotate the third arm to the third arm, A second drive unit is installed on the first arm and includes a second motor and a second power transmission unit that transmits power from the second motor to the second arm. A third drive unit is installed on the first arm and includes a third motor and a third power transmission unit that transmits the power of the third motor to the link mechanism. Equipped with, When the direction along the first axis is defined as the first direction, the direction along the second axis as the second direction, and the direction perpendicular to the first and second directions as the third direction, The second motor and the third motor are spaced apart from the second axis in the first direction. The second motor and the third motor are arranged opposite each other in the third direction. The second output shaft of the second motor and the third output shaft of the third motor extend in the second direction and protrude in opposite directions from each other. [Brief explanation of the drawing]

[0007] [Figure 1] This is a perspective view showing a robot system according to an embodiment of the present invention. [Figure 2] This is a left side view showing a part of the robot in Figure 1. [Figure 3] This is a right side view showing a part of the robot in Figure 1. [Figure 4] This is a cross-sectional view along the line IV-IV in Figure 2. [Figure 5] Figure 1 is a plan view of the first arm of the robot shown. [Figure 6] This is a cross-sectional view along the line VI-VI in Figure 1. [Figure 7] This is a cross-sectional view along the line VII-VII in Figure 1. [Figure 8] This is a cross-sectional view along the line VIII-VIII in Figure 2. [Figure 9]Figure 1 is a left side view showing the range of motion of the plate-shaped link of the robot's second arm and linkage mechanism. [Figure 10] Figure 1 is a left side view showing the range of motion of the fourth arm of the robot. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. Note that the following description does not limit the technical scope or the meaning of terms as defined 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 the robot system 1 according to this 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 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 along the line VI-VI in Figure 1. Figure 7 is a cross-sectional view along the line VII-VII in Figure 1. Figure 8 is a cross-sectional view 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, y, and z axes 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] In addition, in this specification, descriptions such as "orthogonal", "parallel", "the same position, height, dimensions, etc.", and "symmetric" all mean "orthogonal", "parallel", "the same position, height, dimensions, etc.", and "symmetric" to the extent that manufacturing errors are tolerated. Specifically, "orthogonal" means substantially orthogonal, including the range where the angle formed by two straight lines or two planes is 80 degrees or more and 100 degrees or less. "Parallel" means substantially parallel, including the range where the angle formed by two straight lines or two planes is 0 degrees or more and 10 degrees or less. "Two dimensions are the same" means that the two dimensions are substantially the same, including the range where the error between the two dimensions is within ±10%. "Symmetric" means substantially symmetric, including the range where the ratio of the overlapping area to the total area of one of the two elements is 90% or more and 100% or less when one of the two elements is superimposed on the other.

[0012] Also, in FIG. 5, the second motor 151 and the third motor 161 described later are omitted. Further, in FIG. 8, the second motor 151 located on the - side in the y-axis direction from the cross-section of FIG. 8 is virtually shown by a two-dot chain line.

[0013] The robot 10 in the robot system 1 is a parallel link robot and is used for manufacturing food in a broad sense, including, for example, conveyance of food, plating of food, packaging of food, processing of food, etc. In this case, the workpiece (object to be worked on) in the robot system 1 is food or a food package. However, the uses of the robot system 1 and the types of workpieces are not limited to the above.

[0014] Referring to FIG. 1 for a general description, the robot system 1 includes 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 provided with a drive unit 140, and a robot arm 200 that is rotatably connected to the base 110 via a joint 125 and rotates with respect 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 126, 127, 128, link mechanisms 131, 132, and a plurality of drive units 150, 160, 170. Hereinafter, each part of the robot system 1 will be described in detail.

[0015] The base 110 is a support that supports the robot arm 200. The base 110 is installed, for example, on a horizontal plane (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 is also 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 is also 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". Also, in the robot 10, the robot arm 200, and each of the arms 121, 122, 123, 124, etc., the side of the base 110 is also referred to as the "base end side" or "base end portion", and the opposite side is also referred to as the "tip side" or "tip portion".

[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 the present embodiment, each has an overall shape that is a long shape or a shape similar thereto.

[0018] The first arm 121 is mounted above the base 110 along a first axis A1 parallel to the z-axis. 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 arm 121 rotates in a predetermined direction relative to the base 110 by the drive unit 140, the entire robot arm 200, i.e., 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., located on the tip side of the first arm 121, rotates counterclockwise or clockwise around the first axis A1.

[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 xy-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. 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 configuration 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 plate-shaped link 131a, a rod-shaped link 131b, a pivot 131c, and a pivot 131d.

[0027] As will be described in detail later, the base end of the plate-shaped link 131a is positioned on the second axis A2, and the plate-shaped 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 the plate-shaped link 131a is rotatably connected to the base end of the rod-shaped link 131b via a pivot 131c around an axis parallel to the second axis A2. The tip of the rod-shaped 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 the state shown in Figure 2), the second axis A2, the central axis of pivot 131c, the central axis of pivot 131d, and the third axis A3 form a parallelogram.

[0029] Therefore, when viewed from the second direction D2, the line L1 is parallel to the line L2. Consequently, when the plate-shaped link 131a rotates due to the drive of the third drive unit 160, the line L1 also rotates accordingly, and the third arm 123 rotates around the third axis A3 so that the line L2 becomes 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 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 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 separated from the fourth joint 128 are rotatably connected by 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 the state shown 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 (the x-axis direction in the state shown in Figure 3), line L5 is parallel to line L6.

[0035] The angle of line L3 with respect to the xy-plane does not change with the rotation angles (positions) of the second arm 122 and the third arm 123. Therefore, the angle of line L4 with respect to the xy-plane remains constant. Consequently, the position of the plate-shaped link 132b also remains constant. Consequently, the angle of line L5 with respect to the xy-plane also remains constant. Therefore, the angle of line L6 with respect to the xy-plane also remains constant. Thus, 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 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 a processor such as a CPU (Central Processing Unit), a storage unit composed of volatile memory such as RAM (Random Access Memory), non-volatile memory such as ROM (Read Only Memory), and a communication unit that transmits and receives signals with the robot 10. 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 xy plane, and a pair of side plate portions 121c and 121d connected to both ends of the bottom plate portion 121b in a second direction D2 and extending along the z axis. The arm base 121a is a housing that has an open upper surface (a surface parallel to the xy plane), and a shape in which parts of the positive and negative sides of the third direction D3 (surfaces parallel to the xz 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 base 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 base 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. 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 further have a front plate portion attached to the end of the bottom plate portion 121b on the third direction D3- side and extending in the z-axis direction, or a back plate portion attached to the end of the bottom plate portion 121b on the third direction D3+ side and extending in the z-axis direction. Also, 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, by forming a desired shape from a single metal plate by press working or the like. Furthermore, the first axis A1 may be located off-center from the center when viewed from above the first arm 121.

[0045] As shown in Figure 8, the second joint 126, which connects the second arm 122 to the first arm 121 so as to be rotatable around the second axis A2, is provided on the upper part of a 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 of the shaft 126a, and a bearing portion 126c that rotatably holds the other end of the shaft 126a.

[0046] As shown in Figure 5, the shaft 126a is located in the center of the bottom plate portion 121b in the third direction D3 when viewed from the first direction D1 (z-axis direction), and extends along the second direction D2 from one side plate portion 121c to the other side plate portion 121d. Therefore, in this embodiment, the second axis A2, which is the central axis of the shaft 126a, is perpendicular to the first axis A1. As shown in Figure 8, the base end of the second arm 122 is fixed to the portion between the pair of side plate portions 121c and 121d of the shaft 126a, and the second arm 122 rotates in conjunction with the shaft 126a. Each bearing portion 126b, 126c includes a bearing whose inner ring is fixed to the outer circumference of the shaft 126a, and a bearing holder that holds the outer ring of the bearing and is attached to the arm base 121a of the first arm 121. 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.

[0047] Furthermore, a through hole 131h is formed at the base end of the plate-shaped link 131a of the link mechanism 131, with a diameter larger than the diameter of the shaft 126a, and passing through the plate-shaped link 131a in the thickness direction. The plate-shaped 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.

[0048] 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 plate-shaped link 131a of the link mechanism 131.

[0049] 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 (z-axis direction). 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 splashes 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 splashing 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 production is meaningful. However, parts of the second motor 151 and the third motor 161 may protrude outside the arm base 121a.

[0050] 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 mounted on the upper surface of the bottom plate portion 121b via a mount 151c. As shown in Figures 1, 2, 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 axis A2 when viewed from the first direction D1 (z-axis direction).

[0051] 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. As shown in Figure 8, the third motor 161 is mounted on the upper surface of the bottom plate portion 121b via a mount 161c. As shown in Figures 1, 3, and 4, 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 axis A2 when viewed from the first direction D1 (z-axis direction).

[0052] 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.

[0053] 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.

[0054] 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 along 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 freedom of installation for 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.

[0055] 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 xz plane). The second output axis 151a and the third output axis 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.

[0056] 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.

[0057] Furthermore, as shown in Figure 4, when viewed from the first direction D1 (z-axis direction), 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 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.

[0058] 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. Also, as shown in Figure 9, when each part is viewed transparently from the second direction D2, the shape of the second motor 151 matches the shape of the third motor 161 when inverted with respect to the first axis A1. 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 second direction D2. Moreover, when each part is viewed transparently from the third direction D3 (the y-axis direction in the state shown in Figure 8), the shape of the second motor 151 matches the shape of the third motor 161 when inverted with respect to the first axis A1. 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. Thus, in this specification, "two objects being symmetrical when viewed from a specific direction" means that, when each part is viewed transparently from a specific direction, regardless of its position in the depth direction, the outer shape of one object, when inverted around a predetermined line as the central axis, matches the outer shape of the other object. Therefore, the balance of the arrangement and weight balance of the components at the base end of the robot arm 200 can be improved.

[0059] 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.

[0060] 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 (z-axis direction) 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 with respect to the first direction D1, nor do they have to be line-symmetric with respect to the first axis A1 with respect to the first direction D1.

[0061] 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.

[0062] Furthermore, winding drive systems are lighter and less expensive compared to gear systems such as planetary gears and harmonic drive gears. Therefore, the robot arm 200 can be made lighter and the robot 10 can be made less expensive. 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.

[0063] 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.

[0064] 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. The annular member 154c is an endless belt with the same width, thickness, and circumference as the annular member 153c of the first stage.

[0065] Furthermore, the second power transmission unit 152, as a reduction gear, includes an input-side rotational transmission member 155a provided on the second-stage rotating shaft 154s, an output-side rotational transmission member 155b provided on the shaft 126a of the second joint 126, and an annular member 155c 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 with a diameter greater than the diameter 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.

[0066] 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.

[0067] As shown in Figure 6, when viewed from the second direction D2, the first stage rotation axis 153s is located above the second output axis 151a (towards the z+ direction) and towards the third direction D3+, and is situated on the first axis A1. The second stage rotation axis 154s is located above the first stage rotation axis 153s and is also situated on the first axis A1. Therefore, the first stage rotation axis 153s, the second stage rotation axis 154s, and the second axis A2 are aligned in the first direction D1 (z-axis direction), and when viewed from the second direction D2, they are all located on the first axis A1.

[0068] 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, separated from each other, in order toward the second direction D2+ side.

[0069] 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. The second stage rotating shaft 154s is provided with a third stage input-side rotation transmission member 155a and a second stage output-side rotation transmission member 154b, spaced apart from each other, in order toward the second direction D2+ side.

[0070] 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, suppressing the scattering of foreign matter 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.

[0071] 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.

[0072] 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.

[0073] 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." The output-side rotational transmission member 163b corresponds to the "second rotational transmission member," and the rotating shaft 163s corresponds to the "second rotating shaft."

[0074] 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."

[0075] 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 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.

[0076] In this embodiment, the bearing section 166 is composed of two bearings 166a. 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 shaft 126a of the second joint 126. In addition, the plate-shaped link 131a is fixed to the side surface of the output-side rotation transmission member 165b. As a result, the plate-shaped link 131a rotates in conjunction with the third drive unit 160, independently of the rotation of the shaft 126a of the second joint 126.

[0077] As shown in Figure 7, when viewed from the second direction D2, the first stage rotation axis 163s is located above the third output axis 161a (towards the + side of the z-axis) and in the - side of the third direction D3, and is situated on the first axis A1. The second stage rotation axis 164s is located above the first stage rotation axis 163s and is situated on the first axis A1. Therefore, the first stage rotation axis 163s, the second stage rotation axis 164s, and the second axis A2 are aligned in the first direction D1 (in the z-axis direction), and when viewed from the second direction D2, they are all located on the first axis A1.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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 plate-shaped link 131a of the link mechanism 131 rotates.

[0082] Thus, both the second power transmission unit 152 and the third power transmission unit 162 are composed of 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 members (small diameter pulleys), output-side rotational transmission members (large diameter pulleys), annular members (belts), and bearings, which are located in the same stage.

[0083] 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.

[0084] 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 to 20 and preferably 2 to 10. 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] Therefore, as shown in Figure 5, when viewed from the first direction D1 (z-axis direction), 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.

[0089] Furthermore, as shown in Figure 8, the positions (heights) of the rotating shafts located on the same stage in the second power transmission unit 152 and the third power transmission unit 162 are the same in the first direction D1 (z-axis direction). Therefore, although a part of the third power transmission unit 162 is omitted from the illustration in Figure 9, the outer shape of the third power transmission unit 162, when viewed transparently from the second direction D2, matches the outer diameter of the second power transmission unit 152. 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 second direction D2. Moreover, when viewed from the third direction D3, the outer shape of the second power transmission unit 152 is inverted with respect to the first axis A1, and it matches the outer shape of the third power transmission unit 162. 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 at the base end of the robot arm 200 can be improved.

[0090] 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.

[0091] 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 reducer 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 reducer may also be a single-stage reducer. The reducer 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 reducer 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.

[0092] Furthermore, in the robot 10, the first-stage bearings 153t, 163t and the second-stage bearings 154t, 164t may each be slidably mounted on the arm base 121a of the first arm 121 in the first direction D1 (z-axis direction). 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 can 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.

[0093] 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, the second power transmission unit 152 and the third power transmission unit 162 need to be separated 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.

[0094] 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 (z-axis direction) and the second direction D2 (a plane parallel to the xz-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.

[0095] 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.

[0096] This allows the base end of the robot arm 200 to 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.

[0097] Furthermore, as shown in Figure 8, the second arm 122 and the plate-shaped link 131a of the link mechanism 131 are located above the output-side rotational transmission members 154b and 164b of the second-stage reduction gear. Therefore, as shown in Figure 9, the range of motion of the second arm 122 and the plate-shaped link 131a is set to a range that does not interfere with the output-side rotational transmission members 154b and 164b of the second-stage reduction gear. The further the rotation axes 154s and 164s of the second-stage reduction gear move away from the boundary surface P1 in the third direction D3, the narrower the range of motion of the second arm 122 and the plate-shaped link 131a becomes. Therefore, by positioning the second rotation axes 154s and 164s between the first plane P11 and the second plane P12, the range of motion of the second arm 122 and the plate-shaped link 131a can be increased compared to the case where the second rotation axes 154s and 164s are positioned outside the space between the first plane P11 and the second plane P12.

[0098] 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 placed 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 plate-shaped link 131a.

[0099] 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.

[0100] As described above, the robot 10 according to this embodiment includes a first arm 121, a second arm 122, a third arm 123, a link mechanism 131, a second drive unit 150, and a third drive unit 160. The first arm 121 is installed along the first axis A1. The second arm 122 is rotatably connected to the first arm 121 around a second axis A2 which is not parallel to the first axis A1. The third arm 123 is rotatably connected to the second arm 122 around a third axis A3 which is parallel to the second axis A2. The link mechanism 131 transmits power to rotate the third arm 123 to the third arm 123. The second drive unit 150 has a second motor 151 and a second power transmission unit 152 which transmits power from the second motor 151 to the second arm 122, and is installed on the first arm 121. The third drive unit 160 includes a third motor 161 and a third power transmission unit 162 that transmits power from the third motor 161 to the link mechanism 131, and is installed on the first arm 121. The direction along the first axis A1 is defined as the first direction D1, the direction along the second axis A2 as the second direction D2, and the direction perpendicular to the first direction D1 and the second direction D2 as the third direction D3. In this case, the second motor 151 and the third motor 161 are spaced apart from the second axis A2 in the first direction D1, and are positioned opposite each other in the third direction D3. The second output shaft 151a of the second motor 151 and the third output shaft 161a of the third motor 161 extend in the second direction D2 and protrude in opposite directions from each other.

[0101] As described above, since the second motor 151 and the third motor 161 are positioned opposite each other in the third direction D3, the second motor 151 and the third motor 161 can be compactly arranged in the second direction D2. Furthermore, since the second output shaft 151a and the third output shaft 161a protrude in opposite directions from each other in the second direction D2, the second power transmission unit 152 and the third power transmission unit 162 can be compactly arranged in the third direction D3. As a result, the width of the assembly of the first arm 121, the second drive unit 150, and the third drive unit 160 (the base end of the robot arm 200) can be reduced. This increases the degree of freedom when installing the robot 10 and expands the range of motion of the tip of the robot arm 200.

[0102] Furthermore, the robot 10 is further equipped with a base 110, and the first arm 121 is connected to the base 110 so as to be rotatable around the first axis A1. In this way, the rotation of the first arm around the first axis A1 increases the degree of freedom when moving the tip of the robot arm 200. And, as mentioned above, because the width of the base end of the robot arm 200 is reduced, interference between the base end of the robot arm 200 and surrounding objects can be suppressed when the first arm 121 rotates.

[0103] Furthermore, when 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, the second output axis 151a and the third output axis 161a are positioned on opposite sides of the boundary surface P1. Therefore, the base end of the robot arm 200 can be miniaturized in the third direction D3. This increases the degree of freedom when installing the robot 10 and expands the range of motion of the tip of the robot arm 200. In addition, the weight balance of the base end of the robot arm 200 can be improved.

[0104] Furthermore, the second power transmission unit 152 includes a first rotational transmission member (output-side rotational transmission member 153b) whose position in the first direction D1 is between the position of the second output shaft 151a and the position of the second shaft A2, and which transmits the power of the second motor 151 while rotating. The third power transmission unit 162 includes a second rotational transmission member (output-side rotational transmission member 163b) whose position in the first direction D1 is between the position of the third output shaft 161a and the position of the second shaft A2, and which transmits the power of the third motor 161 while rotating. The first rotation axis 153s of the first rotation transmission member 153b and the second rotation axis 163s of the second rotation transmission member 163b each extend in the second direction D2 and are located between the first plane P11, which passes through the second output axis 151a and is parallel to the first direction D1 and the second direction D2, and the second plane P12, which passes through the third output axis 161a and is parallel to the first plane P11. Therefore, the base end of the robot arm 200 can be miniaturized in the third direction D3. This increases the degree of freedom when installing the robot arm 200 and expands the range of motion of the tip of the robot arm 200.

[0105] Furthermore, the second drive unit 150 and the third drive unit 160 are arranged point-symmetrically with respect to the first axis A1 when viewed from the first direction D1. Therefore, the weight balance of the base end of the robot arm 200 can be improved.

[0106] Furthermore, the second drive unit 150 and the third drive unit 160 are arranged symmetrically with respect to the first axis A1 when viewed from the second direction D2. This allows for good weight balance at the base end of the robot arm 200.

[0107] Furthermore, the first arm 121 has an arm base 121a that houses the second motor 151 and the third motor 161 internally. Therefore, the second motor 151 and the third motor 161 are prevented from being exposed to the outside. This prevents surrounding objects from coming into contact with the second motor 151 and the third motor 161. In addition, the scattering of lubricating oil and other foreign matter from the second motor 151 and the third motor 161 to the outside is prevented.

[0108] Furthermore, the model number of the second motor 151 and the model number of the third motor 161 are the same. The second power transmission unit 152 and the third power transmission unit 162 each have input-side rotational transmission members 153a, 163a of the same diameter, output-side rotational transmission members 153b, 163b of the same diameter, and annular members 153c, 163c of the same circumference and width that are wrapped around the input-side rotational transmission members 153a, 163a and the output-side rotational transmission members 153b, 163b. This reduces the number of types of parts that need to be prepared to manufacture the robot 10 during manufacturing. As a result, the robot 10 can be manufactured efficiently and costs can be reduced. As a result, the productivity of the robot 10 can be improved. In addition, during use, the number of types of parts that need to be prepared for replacement of deteriorated or faulty parts can be reduced, making maintenance of the robot 10 easier and reducing maintenance costs.

[0109] Although the robot system and robot of the present invention have been described above in the illustrated embodiments, the present invention is not limited to these embodiments. Furthermore, each part of the robot system and robot can be replaced with any structure capable of performing similar functions. In addition, any structure may be added to the robot system and robot. [Explanation of Symbols]

[0110] 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, 125...First joint, 126...Second joint, 126a...Shaft, 126b...Bearing part, 126c...Bearing part, 127...Third joint, 128...Fourth joint, 131...Link mechanism, 131a...Link, 131b...Link, 131c...Pivot, 13 1d...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 section, 153a...Input side rotation transmission member, 153b...Output side rotation transmission member (first rotation transmission member), 153c...Annular member, 153s...Rotating shaft (first rotating shaft), 153t...Bearing 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, 161c...Mount, 162...Third power transmission part, 162b...Output side rotation transmission member, 163a...Input side rotation transmission member, 163b...Output side rotation transmission member (second rotation transmission member), 163c...Annular member, 163s...Rotating shaft (second rotation shaft) ), 163t...bearing section, 164a...input side rotation transmission member, 164b...output side rotation transmission member, 164c...annular member, 164s...rotating shaft, 164t...bearing section, 165a...input side rotation transmission member, 165b...output side rotation transmission member, 165c...annular member, 166...bearing section, 166a...bearing, 170...fourth drive unit, 200...robot arm, 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, L1...straight line, L2...straight line, L3...straight line, L4...straight line,L5…line, L6…line, P1…boundary plane, P11…first plane, P12…second plane

Claims

1. A first arm is installed along the first axis, A second arm is rotatably connected to the first arm around a second axis that is not parallel to the first axis, A third arm is connected to the second arm so as to be rotatable around a third axis parallel to the second axis, A link mechanism that transmits power to rotate the third arm to the third arm, A second drive unit is installed on the first arm and includes a second motor and a second power transmission unit that transmits power from the second motor to the second arm. A third drive unit is installed on the first arm and includes a third motor and a third power transmission unit that transmits the power of the third motor to the link mechanism. Equipped with, When the direction along the first axis is defined as the first direction, the direction along the second axis as the second direction, and the direction perpendicular to the first and second directions as the third direction, The second motor and the third motor are spaced apart from the second axis in the first direction. The second motor and the third motor are arranged opposite each other in the third direction. A robot characterized in that the second output shaft of the second motor and the third output shaft of the third motor extend in the second direction and protrude in opposite directions from each other.

2. With an additional base, The robot according to claim 1, wherein the first arm is rotatably connected to the base about the first axis.

3. The robot according to claim 1 or 2, wherein, when the second axis passes through a plane parallel to the first and second directions, the second output axis and the third output axis are arranged on opposite sides of the boundary surface.

4. The second power transmission unit includes a first rotational transmission member whose position in the first direction is between the position of the second output shaft and the position of the second shaft, and which transmits the power of the second motor while rotating. The third power transmission unit includes a second rotational transmission member whose position in the first direction is between the position of the third output shaft and the position of the second shaft, and which transmits the power of the third motor while rotating. The robot according to claim 1 or 2, wherein the first rotation axis of the first rotation transmission member and the second rotation axis of the second rotation transmission member each extend in the second direction and are located between a first plane passing through the second output axis and parallel to the first and second directions, and a second plane passing through the third output axis and parallel to the first plane.

5. The robot according to claim 1 or 2, wherein the second drive unit and the third drive unit are arranged point-symmetrically with respect to the first axis when viewed from the first direction.

6. The robot according to claim 1 or 2, wherein the second drive unit and the third drive unit are arranged symmetrically with respect to the first axis when viewed from the second direction.

7. The robot according to claim 1 or 2, wherein the first arm has an arm base that houses the second motor and the third motor inside.

8. The model number of the second motor and the model number of the third motor are the same. The robot according to claim 1 or 2, wherein the second power transmission unit and the third power transmission unit each include an input-side rotational transmission member of the same diameter, an output-side rotational transmission member of the same diameter, and an annular member of the same circumference and width that is wrapped around the input-side rotational transmission member and the output-side rotational transmission member.

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