robot

Abstract

We provide robots that offer superior convenience. [Solution] The braking mechanism is provided on at least one of the motor and the power transmission unit and includes an engagement wheel with a plurality of engagement protrusions along its outer circumference, a braking member that engages with the engagement protrusions, a biasing member that biases the braking member in the direction of engaging with the engagement protrusions, and a braking member drive unit that moves the braking member away from the engagement wheel against the biasing force of the biasing member by energizing the robot. When the motor and the braking member drive unit are energized, the braking member and the engagement wheel are separated, and when the power to the motor and the braking member drive unit is cut off, the engagement wheel engages with the braking member and the engagement protrusions, restricting rotation in a first direction due to the vertical downward displacement of the part, but allowing rotation in the opposite direction to the first direction.

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[0002] In recent years, due to the soaring labor costs and shortage of human resources in factories, robots with robotic arms are used to perform tasks such as transporting, manufacturing, processing, and assembling objects, and the automation of tasks that have been carried out manually is being attempted.

[0003] A motor unit having a brake, a motor, a speed reducer, etc. is installed at the joint of the robotic arm. According to this motor unit, a driving force for operating the robot is output, and a brake can be applied to the driving force when necessary.

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, when the brake is not operating, for example, when the power supply to the robot is cut off due to a power failure or the like, there is a risk that the tip of the robotic arm or the like will be displaced vertically downward due to its own weight. On the other hand, when the brake is operating, it is difficult for a person to apply an external force to raise the tip of the robotic arm, and there is a problem of poor convenience.

Means for Solving the Problems

[0006] The robot according to an application example of the present invention includes a first member, a second member that is displaceably installed with respect to the first member and has a portion that is displaced in a direction including a vertical component, The system comprises a drive unit for driving the second member, The drive unit includes a motor, a power transmission unit that transmits the rotational force output by the motor to the second member, and a brake mechanism that restricts the vertical downward displacement of the part. The brake mechanism includes an engagement wheel provided on at least one of the motor and the power transmission unit, having a plurality of engagement protrusions along its outer circumference; a braking member that moves along the axis and engages with the engagement protrusions; a biasing member that biases the braking member along the axis in a direction that engages with the engagement protrusions; and a braking member drive unit that, by energizing, moves the braking member along the axis in a direction that separates it from the engagement wheel. When the motor and the braking member drive unit are energized, the braking member separates from the engaging wheel. When the power supply to the motor and the braking member drive unit is cut off, the engaging wheel is restricted from rotating in the first direction, which involves a vertical downward displacement of the part, as the braking member engages with the engaging projection, but it is still rotatable in the direction opposite to the first direction. [Brief explanation of the drawing]

[0007] [Figure 1] This is a perspective view showing a robot system comprising a robot according to the first 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]A left side view showing the movable range of the link of the second arm and the link mechanism of the robot shown in FIG. 1. [Figure 10] A left side view showing the movable range of the fourth arm of the robot shown in FIG. 1. [Figure 11] A side view of the brake mechanism provided in the robot shown in FIG. 1, showing the engaged state. [Figure 12] A side view of the brake mechanism provided in the robot shown in FIG. 1, showing the non-engaged state. [Figure 13] A partially enlarged view of the engaged state (braking state) of the brake mechanism shown in FIG. 11. [Figure 14] A partially enlarged view of the non-engaged state (non-braking state) of the brake mechanism shown in FIG. 12. [Figure 15] A side view of the brake mechanism provided in the robot according to the second embodiment of the present invention. [Figure 16] A side view of the brake mechanism provided in the robot according to the third embodiment of the present invention. [Figure 17] A side view of the brake mechanism provided in the robot according to the fourth embodiment of the present invention. [Figure 18] A side view of the brake mechanism provided in the robot according to the fifth embodiment of the present invention. [Figure 19] A side view of the brake mechanism provided in the robot according to the sixth embodiment of the present invention. [Figure 20] A perspective view showing a robot system including the robot according to the seventh embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. Note that the following description does not limit the technical scope or the meaning of the terms described in the claims. Also, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios.

[0009] <First Embodiment> FIG. 1 is a perspective view showing a robot system including a robot according to a first embodiment of the present invention. FIG. 2 is a left side view showing a part of the robot in FIG. 1. FIG. 3 is a right side view showing a part of the robot in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. FIG. 5 is a plan view of the first arm of the robot shown in FIG. 1. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 1. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 1. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 2. FIG. 9 is a left side view showing the movable range of the link of the second arm and the link mechanism of the robot shown in FIG. 1. FIG. 10 is a left side view showing the movable range of the fourth arm of the robot shown in FIG. 1. FIG. 11 is a side view of the brake mechanism provided in the robot shown in FIG. 1, showing an engaged state. FIG. 12 is a side view of the brake mechanism provided in the robot shown in FIG. 1, showing a non-engaged state. FIG. 13 is a partially enlarged view of the engaged state (braking state) of the brake mechanism shown in FIG. 11. FIG. 14 is a partially enlarged view of the non-engaged state (non-braking state) of the brake mechanism shown in FIG. 12.

[0010] Hereinafter, for convenience of explanation, in each figure, as three axes orthogonal to each other, the x-axis, the y-axis, and the z-axis are illustrated with arrows. In the present embodiment, the x-axis is an axis along one direction in the horizontal direction, 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. Also, the tip side of each illustrated arrow is defined as the "positive side (+ side)", and the base end side is defined as the "negative side (- side)". Further, the + side in the z-axis direction is referred to as "up" or "above", and the - side in the z-axis direction is referred to as "down" or "below".

[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 y-axis side of 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 handling, 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 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 structure that supports the robot arm 200. The base 110 is installed on a horizontal surface (installation surface) parallel to the xy 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." Furthermore, the joint 125 will also 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." In addition, 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 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 reduces the rotational speed of the motor's power before transmission. 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 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 link 131a, a link 131b, a pivot 131c, and a pivot 131d.

[0027] As will be described in 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 rod-shaped link 131b via pivot 131c around an axis parallel to the second axis A2. The tip of rod-shaped link 131b is rotatably connected to the base end of the third arm 123 via 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 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 and 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 attached to 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 link 132b, a rod-shaped link 132c, a pivot 132d, a pivot 132e, a pivot 132f, and a pivot 132g. The shape of 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 + 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 link 132b are rotatably connected by pivot 132e around an axis of rotation parallel to the second axis A2. The other corner of the 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 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 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 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 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 has 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), 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, and 170 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] 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 part of the positive and negative surfaces (surfaces parallel to the xz plane) in a third direction D3 that are perpendicular to the side plate portions 121c and 121d, respectively, 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 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.

[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, a second power transmission unit 152 that transmits the power of the second motor 151 to the shaft 126a, and a brake mechanism 3a. Similarly, the third drive unit 160 includes a third motor 161, a third power transmission unit 162 that transmits the power of the third motor 161 to the link 131a of the link mechanism 131, and a brake mechanism 3b.

[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. 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 mounted on the rotor and serving as the rotor's axis of rotation, and a second housing 151b that houses the rotor and stator and exposes (protrudes) 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 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 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.

[0051] The second motor 151 is energized by the control device 20 controlling a motor driver (not shown), and its drive is controlled as desired.

[0052] Similarly, the third motor 161 includes a rotor and stator (not shown), a third output shaft 161a mounted on the rotor and serving as the rotor's axis of rotation, and a third housing 161b that houses the rotor and stator and exposes (protrudes) the tip of the third output shaft 161a. The third motor 161 is mounted on the upper surface of the bottom plate 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 axis A2 when viewed from the first direction D1.

[0053] The third motor 161 is energized and its drive is controlled by the control device 20 controlling a motor driver (not shown).

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 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.

[0060] 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 external shape of the second motor 151 matches that 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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 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, and when viewed from the second direction D2, they are all located on the first axis A1.

[0070] 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.

[0071] 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.

[0072] 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 barriers, suppressing the scattering of foreign matter from 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.

[0073] 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.

[0074] 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.

[0075] 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."

[0076] 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."

[0077] 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 the link 131a and the side plate portion 121d.

[0078] 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 link 131a is fixed to the side surface of the output-side rotation transmission member 165b. As a result, the link 131a rotates in conjunction with the third drive unit 160, independently of the rotation of the shaft 126a of the second joint 126.

[0079] 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 towards 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, and when viewed from the second direction D2, they are all located on the first axis A1.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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 member (small diameter pulley), output-side rotational transmission member (large diameter pulley), and annular member (belt) coaxial bearing, which are located at the same stage.

[0085] 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, making maintenance of the robot 10 easier. 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.

[0086] 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.

[0087] 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.

[0088] If the gearbox has three stages, the reduction ratio of the first stage is preferably 1.1 or more and 2 or less, the reduction ratio of the second stage is preferably 1.1 or more and 2 or less, and the reduction ratio of the third stage is preferably 1.2 or more and 5 or less.

[0089] 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.

[0090] 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.

[0091] 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 outer shape of the second power transmission unit 152 is inverted with respect to the first axis A1. 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.

[0092] 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.

[0093] 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.

[0094] 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 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.

[0095] 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 162 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.

[0096] 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 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.

[0097] 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.

[0098] 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.

[0099] 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 gear. 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 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 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.

[0100] 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 link 131a.

[0101] The robot 10 has been described above, but its configuration is not limited to that described. 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.

[0102] Next, the brake mechanisms 3a and 3b shown in Figure 4 will be described. The braking mechanism 3a has the function of restricting the rotation of the second arm 122 in the direction of gravity (clockwise in Figure 2) when the power supply to the robot 10 is interrupted, for example, due to a power outage. In other words, the braking mechanism 3a has the function of restricting the displacement (descent) of the part of the second arm 122 other than the peripheral part of the second axis A2 when the power supply to the robot 10 is interrupted.

[0103] The braking mechanism 3b has the function of restricting the rotation of the third arm 123 in the direction of gravity (clockwise in Figure 2) when the power supply to the robot 10 is interrupted, for example, due to a power outage. In other words, the braking mechanism 3b has the function of restricting the displacement (descent) of the part of the third arm 123 other than the peripheral part of the third axis A3 (hereinafter referred to as "part 300") (see Figures 1 to 3) vertically downward when the power supply to the robot 10 is interrupted.

[0104] Since brake mechanisms 3a and 3b have substantially the same configuration except for differences in their installation position, installation orientation, and the parts whose displacement is restricted, brake mechanism 3b will be described as a representative example below.

[0105] As shown in Figure 11, the brake mechanism 3b includes an engaging wheel 31, a braking member 32, a biasing member 33, a braking member drive unit 34, and a fixing member 35.

[0106] The engaging wheel 31 is a disc-shaped member fixed concentrically to the third output shaft 161a of the third motor 161. The engaging wheel 31 is fixed to the tip of the third output shaft 161a, that is, to the -x-axis end of the third output shaft 161a, and rotates together with the rotation of the third output shaft 161a. The rotation axis A31 (central axis) of the engaging wheel 31 and the rotation axis of the third output shaft 161a coincide. However, the configuration is not limited to this, and for example, the engaging wheel 31 may rotate via an intermediate gear (not shown) fixed to the rotation axis A31 and meshing with the engaging wheel 31, so the rotation axis A31 (central axis) of the engaging wheel 31 and the rotation axis of the third output shaft 161a do not necessarily coincide.

[0107] The third output shaft 161a, which is the rotation axis of the rotor of the third motor 161, can rotate in either forward or reverse direction when energized. When it rotates clockwise in Figure 11, the third arm 123 rotates such that part 300 of the third arm 123 is displaced vertically downward (downward). On the other hand, when it rotates counterclockwise in Figure 11, the third arm 123 rotates such that part 300 of the third arm 123 is displaced vertically upward (upward).

[0108] The engaging wheel 31 has a plurality of engaging protrusions (teeth) 311 provided at equal intervals along its outer circumference. In the illustrated configuration, the engaging wheel 31 is composed of a gear, such as a spur gear, and the engaging protrusions 311 are the teeth of the gear. However, the engaging wheel 31 composed of a gear is not limited to a spur gear, and may be a helical gear, screw gear, or treble gear, for example. Furthermore, the engaging wheel 31 is not limited to a gear. That is, the engaging wheel 31 may be, for example, a disc-shaped, cylindrical, or ring-shaped member with engaging protrusions 311 composed of protrusions other than teeth on its outer circumference.

[0109] The engaging projection 311 is the part that engages with the braking member 32, and is formed on the outer circumference of the engaging wheel 31. It is composed of teeth that protrude radially outward from the center of the engaging wheel 31 in a V-shape. Each engaging projection 311 has the same tooth width, pitch, and projection height. However, it is not limited to this configuration. At least one of these may differ for each engaging projection 311.

[0110] To explain the x-axis positional relationship of the engagement wheel 31 with respect to the input-side rotation transmission member 163a, as shown in Figures 4 and 11, the engagement wheel 31 is located on the +x-axis side of the third output shaft 161a, relative to the input-side rotation transmission member 163a. ​​In other words, the engagement wheel 31 is located on the opposite side of the third housing 161b of the input-side rotation transmission member 163a. ​​This allows for easy maintenance of the engagement wheel 31, such as cleaning or attaching / detaching it, without the input-side rotation transmission member 163a or the third housing 161b interfering with the maintenance operation.

[0111] The maximum outer diameter of the engaging wheel 31 is larger than the maximum outer diameter of the input-side rotation transmission member 163a. ​​This allows the braking effect of the brake mechanism 3b to be fully realized. In other words, the tooth width and tooth length of each engaging projection 311 can be made larger, making the engagement with the braking member 32 more reliable and stronger. Furthermore, the above maintenance operation can be made easier.

[0112] The maximum outer diameter of the engaging wheel 31 may be the same as, or smaller than, the maximum outer diameter of the input-side rotation transmission member 163a.

[0113] As shown in Figure 11, the braking member 32 is fixed to the tip, i.e., the lower end, of the shaft 341 of the braking member drive unit 34. The braking member 32 is made of, for example, a hammerhead or a similar member. The braking member 32 moves up and down along the central axis A32 (axis) of the shaft 341 of the braking member drive unit 34, and can be in an engaged state where it engages with the engaging projection 311 (see Figure 11) and an unengaged state where it does not engage with the engaging projection 311 (see Figure 12). Here, the engaged state is also called the braking state, and the unengaged state is also called the non-braking state.

[0114] The braking member 32 has sufficient rigidity to not deform even when force is applied from the engaging projection 311, and is made of, for example, metal or hard resin. The braking member 32 is a cylindrical member having a side surface (outer peripheral surface) 321 and a lower end surface 322, with the lower part of the side surface 321 being the part that engages with the engaging projection 311. The side surface 321 is curved, but is not limited to this configuration; it may be flat or have a toothed shape. Furthermore, the shape, size, etc. of the braking member 32 are not limited to the illustrated configuration.

[0115] The braking member drive unit 34 generates a driving force to move the braking member 32 upward. In the illustrated configuration, it consists of a solenoid having a shaft 341 and a casing 342 through which the shaft 341 is inserted. A permanent magnet (not shown) is installed on the shaft 341, and a coil is installed on the outer circumference of the permanent magnet inside the casing 342. When current is supplied to the coil, the shaft 341 and the braking member 32 installed on it move upward due to electromagnetic induction and maintain their position (attitude). This attitude is called the non-braking attitude when energized (basic attitude). Hereinafter, the state in which the coil is energized is referred to as the energized state of the braking member drive unit 34, and the state in which the coil is not energized is referred to as the de-energized state of the braking member drive unit 34. Thus, when energized, the braking member drive unit 34 takes the non-braking attitude when energized, and when de-energized, it takes the braking attitude when de-energized.

[0116] The braking member drive unit 34 can move the braking member 32 in either the up or down direction. That is, the braking member drive unit 34 can move the braking member 32 along the z-axis direction, so that the braking member 32 can move in either the direction in which it contacts the engaging wheel 31 (-z-axis direction) or in the direction in which it separates from it, i.e., moves away from it (+z-axis direction).

[0117] When the braking member drive unit 34 is de-energized, the shaft 341 can be moved in either the up or down direction when an external force is applied.

[0118] The braking member drive unit 34 is electrically connected to the control device 20, and the control device 20 controls the power supply conditions to the braking member drive unit 34, such as switching between power supply and power off, so that it can be driven at a desired timing.

[0119] The braking member drive unit 34 is installed on the +z axis side and the +y axis side of the engaging wheel 31. The rotation axis A31 of the engaging wheel 31 and the central axis A32 of the direction of movement of the braking member 32 are in a torsional positional relationship that is non-parallel and does not intersect. As a result, the corner on the -y axis side of the braking member 32 engages with the engaging projection 311 located on the +z axis side and the +y axis side of the engaging wheel 31. Thus, as will be described later, the rotation of the engaging wheel 31 can be restricted more reliably in the engaged state. In addition, the arrangement of each component constituting the brake mechanism 3b can be made more appropriate, the installation space of the brake mechanism 3b can be reduced, and this contributes to the miniaturization of the robot arm 200.

[0120] The braking member drive unit 34 is not limited to a solenoid, but may be composed of other drive sources such as a motor, a hydraulically or pneumatically driven cylinder, etc.

[0121] The energization and de-energization timings for the third motor 161 and the braking member drive unit 34 are performed synchronously. The control device 20 controls the energization and de-energization timings for the third motor 161 and the braking member drive unit 34 to be performed synchronously. That is, power is supplied to the third motor 161 and the braking member drive unit 34 from an external power source (not shown) at the same time, and when the power from the external power source is cut off, the third motor 161 and the braking member drive unit 34 are de-energized (power supply is cut off) at the same time.

[0122] Furthermore, the power supply circuit to the third motor 161 and the power supply circuit to the braking member drive unit (solenoid) 34 may be connected in parallel, and in this case as well, the power supply and depower supply to both will be performed synchronously.

[0123] Here, "the timing of powering on and off is synchronized" means that the energized state of the motor 161 and the braking member drive unit 34 overlaps at least partially in time, and the off state of the motor 161 and the braking member drive unit 34 also overlaps at least partially in time. In other words, it is included not only when the start and end times of the energized state and the off state of the motor 161 and the braking member drive unit 34 coincide, but also when at least one of the start and end times does not coincide, in which case "the timing of powering on and off is synchronized." In the latter case, it is preferable that the difference in the start or end time is as small as possible, for example, ±1 second or more and ±5 seconds or less.

[0124] This also applies to the second motor 151 and the braking member drive unit 34 of the brake mechanism 3a.

[0125] The biasing member 33 biases the braking member 32 in the direction that engages with the engaging projection 311, that is, towards the -z axis. In the illustrated configuration, the biasing member 33 is composed of a coil spring provided on the outer circumference of the shaft 341. The biasing member 33 is installed in a compressed state between the shaft 341 and the casing 342 of the braking member 32 and the braking member drive unit 34.

[0126] In the natural state (disconnected state) without any external force, the braking member 32 is biased downward (towards the -z axis) by the biasing force of the biasing member 33. This biasing force allows the braking member 32 to engage with the engaging projection 311 of the engaging wheel 31, resulting in an engaged state (braking position when not energized). On the other hand, when the braking member drive unit 34 is energized, the braking member 32 can be moved away from the engaging wheel 31, i.e., upward (towards the +z axis), against the biasing force of the biasing member 33. This allows the braking member 32 to be separated from the engaging wheel 31, resulting in an unengaged state (non-braking position when energized).

[0127] The biasing member 33 is not limited to a coil spring as shown in the figure, but may be made of other springs such as leaf springs, or other elastic materials such as rubber. Also, the installation position of the biasing member 33 is not limited to the configuration shown in the figure. For example, a coil spring may be used as a tension spring to pull the lower end surface 322 of the braking member 32 downwards and bias it.

[0128] As shown in Figures 4 and 11, the fixing member 35 installs and fixes the braking member drive unit 34 in the position and orientation described above. The fixing member 35 has a base portion 351 fixed to the +x axis side surface of the third housing 161b of the third motor 161, and an installation portion 352 that protrudes from the base portion 351 toward the +z axis, and on which the casing 342 of the braking member drive unit 34 is installed.

[0129] Such a fixing member 35 allows the braking member drive unit 34 to be stably installed in the desired position and orientation. The configuration of the fixing member 35 is not limited to that shown in the figure, and the fixing member 35 itself may be omitted. In this case, it is preferable to have a fixing part provided on the arm base 121a that supports the braking member drive unit 34 instead of the fixing member 35.

[0130] Next, we will explain the operation of the brake mechanism 3b. By energizing the third motor 161, it outputs rotational force, which allows the third arm 123 to rotate in the desired direction via the third power transmission unit 162 and the link mechanism 130.

[0131] Furthermore, the braking member drive unit 34 is energized in sync with the energization of the third motor 161. In this energized state, the braking member drive unit 34 moves the braking member away from the engaging wheel 31, i.e., towards the +z axis, against the biasing force of the biasing member 33. As a result, the brake mechanism 3b is in an unengaged state (non-braking position when energized) and does not hinder the rotation of the third arm 123 caused by the operation of the third motor 161.

[0132] On the other hand, if, for example, a power outage occurs in the factory where the robot 10 is installed, or if the power is unintentionally turned off by human intervention, while the robot arm 200 is in operation, the power supply to the third motor 161 and the braking member drive unit 34 is cut off. In this case, the robot arm 200 stops in the position it was in when the power was cut off, but gravity acts on the robot arm 200, causing it to move vertically downward.

[0133] Focusing on the third arm 123 and the third motor 161, after the robot arm 200 is stopped due to the power being cut off, gravity acts on the third arm 123 in a direction that displaces part 300 vertically downward, that is, a clockwise rotational force (torque) around the third axis A3 in Figure 2. This rotational force is transmitted in the opposite direction from the third arm 123 via the third power transmission unit 162, attempting to rotate the engagement wheel 31 clockwise in Figure 11. Also, with the power cut off, the braking member 32 moves downward (towards the -z axis) due to the biasing force of the biasing member 33. Due to this movement, the braking member 32 engages with the engagement projection 311 of the engagement wheel 31, which is fixed to the third output shaft 161a of the third motor 161, and enters an engaged state (braking position when not energized).

[0134] In this engaged state, a force F1 along the tangential direction of the engaging wheel 31 is applied from the engaging projection 311 of the engaging wheel 31, particularly the engaging projection 311A ​​in Figure 13, to the side surface 321 of the braking member 32. This force F1 does not have a component that lifts the braking member 32 upward (towards the +z axis), and therefore the braking member 32 cannot be raised. As a result, the engaged state is maintained, and rotation of the third arm 123 due to the action of gravity can be prevented after the robot arm 200 has stopped.

[0135] On the other hand, even when the third motor 161 and the braking member drive unit 34 are disconnected, there may be situations where the operator wants to apply force to the robot arm 200 to displace it in the opposite direction to gravity (upward). For example, this would apply when the tip of the robot arm 200 (the fourth arm or the end effector E1 attached thereto) is at the same level as or below the work surface, or when the operator wants to raise the tip of the robot arm 200 to remove a workpiece between the tip and the work surface. This would also apply when, after returning to an energized state from a disconnected state, the operator wants to raise the tip of the robot arm 200 to a desired height in order to quickly resume work.

[0136] When an operator applies force to lift the robot arm 200, this force generates a counterclockwise rotational force (torque) around the third axis A3 in Figure 2 on the third arm 123. This rotational force is transmitted in the reverse direction from the third arm 123 via the third power transmission unit 162, causing the third output shaft 161a of the third motor 161 and the engagement wheel 31 fixed thereto to rotate counterclockwise in Figure 11.

[0137] In this case, a force F2 is applied to the lower end surface 322 of the braking member 32 from the engaging projection 311B of the engaging wheel 31, which is adjacent to the engaging projection 311A ​​in Figure 14 that engages with the braking member 32 (located directly below the braking member 32), along the tangential direction of the engaging wheel 31. This force F2 has a component that lifts the braking member 32 upward (towards the +z axis) along the central axis A32, allowing the operator to raise the braking member 32 against the biasing force of the biasing member 33.

[0138] As the operator continues to apply force to lift the robot arm 200, that is, to displace it in the opposite direction to gravity, the engagement wheel 31 attempts to rotate counterclockwise in Figure 11. The engagement projection 311 located directly below the braking member 32 moves over the lower end surface 322 of the braking member 32, and the next engagement projection 311 contacts the lower end surface 322, lifting the braking member 32. By repeating this operation, the portion 300 of the third arm 123 can be displaced vertically upward, that is, the third arm 123 can be lifted.

[0139] When the operator releases the force lifting the robot arm 200, gravity again acts on the third arm 123, creating a clockwise rotational force around the third axis A3 in Figure 2. This rotational force is transmitted in the reverse direction via the third power transmission unit 162, causing the engagement wheel 31 to rotate clockwise in Figure 11, resulting in an engaged state (see Figure 11).

[0140] Thus, when the third motor 161 and the braking member drive unit 34 are powered off (power is cut off), the engaging wheel 31 engages with the braking member 32 and the engaging projection 311, restricting the clockwise rotation in Figure 11 (rotation in the first direction) associated with the vertical downward displacement of the third arm 123, but allowing counterclockwise rotation in Figure 11 (rotation in the opposite direction to the first direction). This allows the robot arm 200 to be displaced downward by gravity while the power to the third motor 161 and the braking member drive unit 34 is cut off, and also allows the robot arm 200 to be displaced in the opposite direction to gravity (upward) by releasing this restriction (contrary to the restriction). Therefore, the robot arm 200 can be safely displaced to a desired position while the power is cut off. This provides superior safety and convenience.

[0141] Furthermore, when power is restored to the third motor 161 and the braking member drive unit 34 from the power-off state, as shown in Figure 12, the braking member drive unit 34 moves the braking member 32 away from the engagement wheel 31, i.e., upward (towards the +z axis), against the biasing force of the biasing member 33, thereby enabling it to be in an unengaged state (non-braking position when power is supplied). As a result, the rotational force output by the motor 161 drives the third arm 123 without being restricted by the brake mechanism 3b, and the robot arm 200 can perform the desired operation.

[0142] The brake mechanism 3b has been described above. In the brake mechanism 3a, although the orientation of the braking member 32, biasing member 33, braking member drive unit 34, and fixing member 35 is different, it has the same configuration as the brake mechanism 3b described above and produces the same operation and effect. To briefly explain the main points, in the brake mechanism 3a, the braking member 32, biasing member 33, and braking member drive unit 34 are provided on the +y axis side and the -z axis side with respect to the engagement wheel 31 fixed to the output shaft 151a of the motor 151. In addition, the braking member drive unit 34 moves the braking member 32 along the y axis.

[0143] By arranging the components in this manner, the brake mechanism 3a can effectively utilize the available space within the arm base 121a of the first arm 121, thereby enabling a miniaturization of the first arm 121.

[0144] However, the position and orientation of the brake mechanism 3a relative to the first arm 121 are not limited to those described above.

[0145] As described above, the robot 10 comprises a second arm 122 which is an example of a first member, a third arm 123 which is an example of a second member and is displaceably mounted relative to the second arm 122 and has a portion 300 that is displaceable in a direction including a vertical component, and a drive unit 160 that drives the third arm 123. The drive unit 160 comprises a third motor 161 which is an example of a motor, a third power transmission unit 162 which is an example of a power transmission unit that transmits the rotational force output by the third motor 161 to the third arm 123, and a brake mechanism 3b that restricts the vertical downward displacement of the portion 300 of the third arm 123. The brake mechanism 3b is provided on at least one of the third motor 161 and the third power transmission unit 162 (in this embodiment, the third motor 161) and has multiple brake mechanisms along its outer circumference. The device comprises an engaging wheel 31 provided with an engaging projection 311, a braking member 32 that moves along a central axis A32 (axis) and engages with the engaging projection 311, a biasing member 33 that biases the braking member 32 along the central axis A32 in a direction that engages with the engaging projection 311, and a braking member drive unit 34 that moves the braking member 32 along the central axis A32 in a direction that separates it from the engaging wheel 31 when energized. When the third motor 161 and the braking member drive unit 34 are energized, the braking member 32 separates from the engaging wheel 31, and when the energization to the third motor 161 and the braking member drive unit 34 is cut off, the engaging wheel 31 is restricted from rotating in a first direction with vertical downward displacement of part 300 because the braking member 32 engages with the engaging projection 311, but it can rotate in the direction opposite to the first direction. This allows the robot arm 200 to be displaced in the opposite direction to gravity while the power supply to the third motor 161 and the braking member drive unit 34 is cut off, thereby restricting the displacement of the robot arm 200 due to gravity, and also releasing this restriction to displace the robot arm 200 in the opposite direction to gravity. Therefore, the robot arm 200 can be safely displaced to a desired position while the power is cut off. As a result, it offers superior convenience.

[0146] In the above description, we focused on the brake mechanism 3b and described the "first member" as the second arm 122 and the "second member" as the third arm 123. However, the present invention is not limited to this, and when focusing on the brake mechanism 3a, the "first member" can be considered as the first arm 121 and the "second member" as the second arm 122. In this case, the brake mechanism 3b is provided on at least one of the second motor 151 and the second power transmission unit 152.

[0147] In this embodiment, both brake mechanism 3a and brake mechanism 3b are present. This allows the effects and advantages of the present invention described above to be exhibited more significantly and reliably compared to the case where only one of brake mechanism 3a or brake mechanism 3b is present. However, the present invention is not limited to this, and a configuration having only one of brake mechanism 3a or brake mechanism 3b is also possible.

[0148] Furthermore, although not shown in the figures, the first arm 121 can also be configured to move up and down (raise and lower) relative to the base 110. In this case, the above configuration can be applied to at least one of the drive unit 140 that drives the first arm 121 or the power transmission unit that transmits power to the first arm 121. In this case, the "first member" is the base 110 and the "second member" is the first arm 121.

[0149] Furthermore, although this embodiment describes a case where the brake mechanism 3b is installed on the third motor 161, the brake mechanism 3b is not limited to this and may be provided on the third power transmission unit 162. Specifically, an example is a configuration in which the engaging wheel 31 is provided on at least one of the rotating shafts 163s, 164s, and 126a of the third power transmission unit 162, and the braking member 32, biasing member 33, and braking member drive unit 34 are provided at corresponding locations. In this case as well, the same effects and advantages as the present invention described above are achieved.

[0150] The same applies to providing the brake mechanism 3a in the second power transmission unit 152. Specifically, an engaging wheel 31 is provided on at least one of the rotating shafts 153s, 154s, and 126a of the second power transmission unit 153, and a braking member 32, a biasing member 33, and a braking member drive unit 34 are provided at the corresponding locations. In this case as well, the same effects and advantages as those of the present invention described above are achieved.

[0151] As mentioned above, the rotation axis A31 of the engaging wheel 31 and the central axis A32 (axis) of the braking member 32 are in a torsional positional relationship. This allows for more reliable restriction of the rotation of the engaging wheel 31 caused by the displacement of the robot arm 200 due to gravity when the braking member 32 and the engaging wheel 31 are engaged. In other words, the braking effect of the brake mechanisms 2a and 3a can be obtained more reliably. In addition, the installation space for the brake mechanism 3b can be reduced, contributing to the miniaturization of the robot arm 200.

[0152] The rotation axis A31 of the engaging wheel 31 and the central axis A32 in the direction of movement of the braking member 32 do not necessarily have to be in a torsional positional relationship. For example, the rotation axis of the engaging wheel 31 and the central axis in the direction of movement of the braking member 32 may intersect.

[0153] As described above, the third motor 161 has a third housing 161b which houses the rotor and stator, and a third output shaft 161a which is an output shaft that protrudes from the third housing 161b and serves as the rotation axis of the rotor, and the engagement wheel 31 is fixed to the third output shaft 161a. This more reliably restricts the displacement of the robot arm 200 due to the action of gravity and prevents the part 300 from being displaced downward, and also allows the operator to manually release the restriction (contrary to the restriction) and displace the robot arm 200, in particular the part 300, upward.

[0154] As mentioned above, the third power transmission unit 162, which is an example of a power transmission unit, has an input-side rotation transmission member 163a provided on the third output shaft 161a, which is the output shaft, and the engaging wheel 31 is provided on the opposite side from the third housing 161b, which is the housing of the input-side rotation transmission member 163a. ​​As a result, when performing maintenance operations such as cleaning the engaging wheel 31 or attaching and detaching the engaging wheel 31, the input-side rotation transmission member 163a and the third housing 161b do not get in the way of the maintenance operations, making maintenance operations easy.

[0155] The engaging wheel 31 may be provided between the input-side rotation transmission member 163a and the third housing 161b.

[0156] As mentioned above, the third motor 161 and the braking member drive unit 34, which are examples of motors, are energized and de-energized synchronously. With this configuration, the brake mechanisms 3a and 3b can be operated at a more appropriate timing. Furthermore, the effect of the present invention, namely the ability to safely change the robot arm 200 to a desired posture while the power is cut off, can be demonstrated more significantly, resulting in superior convenience.

[0157] Furthermore, the energization and deenergization timing of the third motor 161 and the braking member drive unit 34 does not necessarily have to be synchronous.

[0158] <Second Embodiment> Figure 15 is a side view of a brake mechanism provided in a robot according to a second embodiment of the present invention.

[0159] The second embodiment of the robot of the present invention will be described below with reference to Figure 15, but the following description will focus on the differences from the first embodiment, and similar matters will be omitted.

[0160] As shown in Figure 15, the brake mechanism 3b in this embodiment has a movement limit restricting member (first movement limit restricting member) 36 that restricts the movement limit of the braking member 32 in the direction approaching the engagement wheel 31 (downward in Figure 15).

[0161] The movement limit restricting member 36 is a block-shaped member located below the braking member 32 and is fixed to the fixing member 35. In the engaged state (non-braking position when energized) when the braking member 32 and the engaging wheel 31 are engaged, the movement limit restricting member 36 contacts the side opposite to the engaging wheel 31 via the central axis A32 in the direction of movement of the braking member 32, that is, it contacts the corner on the +y axis side and the -z axis side of the braking member 32, thereby restricting the movement limit of the braking member 32.

[0162] The movement limit restricting member 36 has a first restricting surface 361 parallel to the xy plane and a second restricting surface 362 parallel to the xz plane. That is, the first restricting surface 361 and the second restricting surface 362 are orthogonal (form a right angle).

[0163] The first restricting surface 361, in the engaged state, contacts the lower end surface 322 on the y-axis + side of the braking member 32, restricting the braking member 32 from moving further downward (towards the -z axis). This absorbs excessive shock when transitioning from the unengaged state to the engaged state, and also prevents excessive load from being placed on the engaging wheel 31 from the braking member 32 while the engaged state is maintained. As a result, excessive load is prevented on the third output shaft 161a of the third motor 161, thereby preventing axial runout of the third output shaft 161a, ensuring proper operation of the third motor 161, improving the positional accuracy of the robot arm 200, and increasing the durability of the third motor 161, and consequently the durability of the robot 10.

[0164] The second restricting surface 362, in the engaged state, contacts the side surface 321 of the braking member 32, restricting the braking member 32 from moving further toward the y-axis + side. As a result, in the engaged state, the second restricting surface 362 absorbs the force (force in the direction from the y-axis - side to the y-axis + side) that the braking member 32 receives when the engaging wheel 31 tries to rotate clockwise in Figure 15. Therefore, it prevents the shaft 341 and casing 342 of the braking member drive unit 34 from being displaced in the same direction due to excessive load, especially a force directed toward the y-axis + side. This allows the braking member drive unit 34 to operate continuously and properly, and increases the durability of the braking member drive unit 34.

[0165] Thus, the brake mechanism 3b has a movement limit restricting member 36 that restricts the movement limit of the braking member 32 in the direction approaching the engagement wheel 31 (downward in Figure 15). This prevents excessive impact or load from being applied from the braking member 32 to the engagement wheel 31 when engaging or while the engagement state is maintained. Therefore, proper operation of the third motor 161 can be ensured, the positional accuracy of the robot arm 200 during operation can be improved, and excessive load can be prevented from being applied to the third output shaft 161a of the third motor 161 (the mounting part of the engagement wheel 31), thereby increasing the durability of the third motor 161 and the braking member drive unit 34, and ultimately the durability of the robot 10.

[0166] In this embodiment, the first restricting surface 361 and the second restricting surface 362 are orthogonal, but are not limited to this, and the angle between the first restricting surface 361 and the second restricting surface 362 may be an angle other than a right angle. The angle between the first restricting surface 361 and the second restricting surface 362 can be set to any angle, for example, depending on the shape of the part of the braking member 32 that contacts the movement limit restricting member 36.

[0167] Furthermore, in the configuration shown in Figure 15, both the first restricting surface 361 and the second restricting surface 362 are planar (flat) surfaces, but the configuration is not limited to this. For example, at least one of the first restricting surface 361 and the second restricting surface 362 may be a curved convex or curved concave surface in which all or part of the surface curves in an arbitrary direction, or a surface having a bent portion in which part of the surface bends in an arbitrary direction. The first restricting surface 361 and the second restricting surface 362 may be smooth surfaces with a relatively low coefficient of friction, or rough surfaces with a relatively high coefficient of friction, but from the viewpoint of maintaining the engagement state, a rough surface is preferred.

[0168] Furthermore, the movement limit restricting member 36 may have a chamfered or concave rounded portion at the boundary between the first restricting surface 361 and the second restricting surface 362.

[0169] Furthermore, the movement limit restricting member 36 may have only one of the first restricting surface 361 and the second restricting surface 362.

[0170] <Third Embodiment> Figure 16 is a side view of a brake mechanism provided in a robot according to a third embodiment of the present invention.

[0171] The third embodiment of the robot of the present invention will be described below with reference to Figure 16, but the following description will focus on the differences from the second embodiment, and similar matters will be omitted.

[0172] As shown in Figure 16, the movement limit restricting member 37 (first movement limit restricting member) in this embodiment has a contact surface 371. In the engaged state (non-braking position when energized) when the braking member 32 and the engaging wheel 31 are engaged, the contact surface 371 contacts the side opposite to the engaging wheel 31 via the central axis A32 in the direction of movement of the braking member 32, that is, it contacts the corner on the y-axis + side and z-axis - side of the braking member 32, thereby restricting the movement limit of the braking member 32.

[0173] The contact surface 371 is composed of a flat surface at least near its center. It is composed of an inclined surface that is at a predetermined angle with respect to the central axis A32 (with respect to the xz plane), for example, any angle in the range of 30° to 60°. The contact surface 371 is inclined toward the z-axis as it moves toward the y-axis. Therefore, the contact surface 371 can perform the respective functions of the first restricting surface 361 and the second restricting surface 362 described in the second embodiment.

[0174] In other words, it is possible to prevent excessive shock or load from being applied from the braking member 32 to the engaging wheel 31 when engaging or while the engaged state is maintained, and to prevent excessive load from being applied to the shaft 341 and casing 342 of the braking member drive unit 34. Therefore, with a simple configuration of providing an inclined contact surface 371 on the movement limit restricting member 37, it is possible to ensure proper operation of the third motor 161, improve the positional accuracy of the robot arm 200, and increase the durability of the third motor 161 and the braking member drive unit 34.

[0175] Since the contact surface 371 is an inclined surface as described above, the same action and effect is achieved regardless of where the corner of the braking member 32 contacts the contact surface 371. Therefore, the movement limit restricting member 37 equipped with the contact surface 371 can fully achieve the same action and effect as described above without requiring precise positioning at a fixed position, compared to the first restricting surface 361 and the second restricting surface 362 of the second embodiment.

[0176] Thus, the movement limit restricting member 37 abuts against the engagement wheel 31 on the opposite side via the central axis A32 (axis) of the braking member 32, and has a contact surface 371 that is inclined with respect to the central axis A32. This prevents excessive impact or load from being applied to the engagement wheel 31 from the braking member 32 when engaging or while the engagement state is maintained. Therefore, proper operation of the third motor 161 can be ensured, the positional accuracy of the robot arm 200 during operation can be improved, and excessive load can be prevented from being applied to the third output shaft 161a (mounting part of the engagement wheel 31) of the third motor 161, thereby increasing the durability of the third motor 161 and the braking member drive unit 34, and ultimately the durability of the robot 10. Furthermore, these effects can be achieved with a simple configuration of providing the movement limit restricting member 37 with an inclined contact surface 371.

[0177] In the configuration shown in Figure 16, the contact surface 371 is a flat surface, but it is not limited to this. For example, the entire or a part of the contact surface 371 may be a curved convex or curved concave surface that curves in any direction, or a part of the contact surface 371 may have a bent portion that bends in any direction. The contact surface 371 may be a smooth surface with a relatively low coefficient of friction, or a rough surface with a relatively high coefficient of friction, but a rough surface is preferable from the viewpoint of maintaining the engagement state.

[0178] Alternatively, the movement limit restricting member 37 may be installed so as to be rotatable around an axis parallel to the x-axis, allowing the inclination angle of the contact surface 371 to be adjusted as appropriate.

[0179] <Fourth Embodiment> Figure 17 is a side view of a brake mechanism provided in a robot according to the fourth embodiment of the present invention.

[0180] The following description will focus on the differences from the previous embodiments of the robot, with reference to Figure 17.

[0181] As shown in Figure 17, the brake mechanism 3b has an operating member 38 for lifting the shaft 341 upward when the power is off. The operating member 38 is made up of a wire connected to the upper end of the shaft 341, that is, the end opposite to the end on which the braking member 32 is provided. The end of the operating member 38 opposite to the braking member 32 (not shown) is exposed to the outside of the first arm 121, and can be grasped and pulled by an operator.

[0182] As shown in Figure 17, when the third motor 161 and the braking member drive unit 34 are powered off, the engaging wheel 31 engages with the braking member 32 and the engaging projection 311, restricting the clockwise rotation (rotation in the first direction) in Figure 17 that occurs with the vertical downward displacement of the third arm 123. However, there may be cases where it is desired to change the posture of the robot arm 200 in a way that displaces the robot arm 200 downward.

[0183] In this case, by pulling the operating member 38 upward, the shaft 341 can be lifted against the biasing force of the biasing member 33. This separates the braking member 32 from the engaging wheel 31 and releases the engagement. Therefore, even when the power is off, it is possible to displace the robot arm 200 upward.

[0184] Furthermore, it is preferable that the arm base 121a of the first arm 121 has a fixing part such as a hook for fixing (hooking) the operating member 38 when it is pulled. This makes it possible to maintain a state in which the robot arm 200 can be displaced upward when the power is off. Thus, it becomes easier to change the posture of the robot arm 200 when the power is off.

[0185] <Fifth Embodiment> Figure 18 is a side view of a brake mechanism provided in a robot according to the fifth embodiment of the present invention.

[0186] The fifth embodiment of the robot of the present invention will be described below with reference to Figure 18, but the following description will focus on the differences from the previous embodiments, and similar matters will be omitted.

[0187] As shown in Figure 18, the brake mechanism 3b has a movement limit restricting member 39 (second movement limit restricting member) that restricts the upward movement limit of the shaft 341.

[0188] The movement limit restricting member 39 is a block-shaped member provided above the end of the shaft 341 opposite to the braking member 32, and is fixed to the fixing member 35. When energized, the movement limit restricting member 39 contacts the upper end of the shaft 341 and has the function of restricting the shaft 341 from moving any further upward.

[0189] By having such a movement limit restricting member 39, for example, when switching from a non-energized state to an energized state, it is possible to restrict the excessive upward movement of the shaft 341 due to the biasing force of the biasing member 33, thereby enabling a more stable switch from an engaged state to an unengaged state.

[0190] Note that the shape of the movement limit restricting member 39 is not limited to the configuration shown in the figure. Furthermore, the movement limit restricting member 39 may be made of an elastic material. Also, the movement limit restricting member 39 may be biased downward by a biasing member (not shown). In any case, the impact when the shaft 341 comes into contact with the movement limit restricting member 39 can be mitigated.

[0191] <Sixth Embodiment> Figure 19 is a side view of a brake mechanism provided in a robot according to the sixth embodiment of the present invention.

[0192] The sixth embodiment of the robot of the present invention will be described below with reference to Figure 19, but the following description will focus on the differences from the previous embodiments, and similar matters will be omitted.

[0193] As shown in Figure 19, the brake mechanism 3b has a buffering mechanism 4 that provides a buffering function against the force that the braking member 32 and the braking member drive unit 34 receive from the engaging wheel 31 when the engaging wheel 31 and the braking member 32 are engaged.

[0194] The shock absorber mechanism 4 is installed on the +y axis side and the +z axis side of the engaging wheel 31. The shock absorber mechanism 4 includes a base 41 fixed to a fixed part 52 (not shown), a movable part 43 connected to the base 41 via a rotating support part 42, a biasing member 44 which is a coil spring installed between the base 41 and the movable part 43, and a stopper 45.

[0195] The rotation support portion 42 has a rotation axis along the x-axis direction. Therefore, the movable portion 43 can rotate around the x-axis. The braking member drive portion 34 is fixed to the movable portion 43. Therefore, the braking member drive portion 34 can rotate together with the movable portion 43 around the x-axis.

[0196] When the movable part 43 rotates so that it moves toward the +y axis, that is, away from the engaging wheel 31, the biasing member 44 deforms in a compressive manner. As a result of this deformation, the biasing force of the biasing member 44 biases the movable part 43 in the opposite direction to the direction of movement. Therefore, a cushioning effect is exerted on the braking member drive unit 34 fixed to the movable part 43.

[0197] This configuration allows the force that the braking member 32 and the braking member drive unit 34 receive from the engaging wheel 31 when engaged to be mitigated. Therefore, the durability of the shaft 341 and the parts supporting the shaft 341 can be increased in particular.

[0198] The stopper 45 is positioned on the opposite side of the brake member drive unit 34 from the movable part 43, i.e., on the -y axis side. The stopper 45 contacts the -y axis side of the brake member drive unit 34, restricting the brake member drive unit 34 and the movable part 43 from moving further toward the -y axis. This prevents the movable part 43 from rotating excessively toward the -y axis due to the biasing force of the biasing member 44. Thus, a more precise engagement state can be obtained.

[0199] <Seventh Embodiment> Figure 20 is a perspective view showing a robot system comprising a robot according to the seventh embodiment of the present invention.

[0200] The following description of the seventh embodiment of the robot of the present invention will be made with reference to Figure 20, but the differences from the above embodiments will be the main focus of the description, and similar matters will be omitted.

[0201] As shown in Figure 20, the robot 10 is a horizontal articulated robot, or SCARA robot. The robot 10 has a base 71 and a robot arm 72 that is rotatably connected to the base 71. The robot arm 72 has a first arm 73 whose base end is connected to the base 71 and rotates around a first rotation axis J1 that is perpendicular to the base 71, and a second arm 74 whose base end is connected to the tip of the first arm 73 and rotates around a second rotation axis J2 that is perpendicular to the first arm 73.

[0202] A working head 75, which serves as a third arm, is provided at the tip of the second arm 74. The working head 75 has a spline nut 751 and a ball screw nut 752 arranged coaxially at the tip of the second arm 74, and a spline shaft 753 inserted through the spline nut 751 and the ball screw nut 752. The spline shaft 753 is rotatable around a third rotation axis J3, which is its central axis and runs vertically along the second arm 74, and is also vertically movable along the third rotation axis J3.

[0203] Furthermore, the robot 10 includes a first drive mechanism 791 that rotates a spline nut 751 to rotate the spline shaft 753 around a third rotation axis J3, and a second drive mechanism 792 that rotates a ball screw nut 752 to raise and lower the spline shaft 753 in a direction along the third rotation axis J3, i.e., in the vertical direction.

[0204] The second drive mechanism 792 is installed below the first drive mechanism 791. The first drive mechanism 791 includes a motor 793, a pulley 794, and a belt 795. The second drive mechanism 792 includes a motor 796, a pulley 797, and a belt 798.

[0205] Motors 793 and 796 are fixed to the arm base 740 of the second arm 74 with their output shafts protruding downwards. Belt 795 is wrapped around the output shaft of motor 793 and spline nut 751. Belt 798 is wrapped around the output shaft of motor 796 and ball screw nut 752. This configuration allows the spline shaft 753 to be rotated around the third rotation axis J3 by rotating the spline nut 751, and the spline shaft 753 to be raised and lowered in the direction along the third rotation axis J3, i.e., vertically, by rotating the ball screw nut 752.

[0206] In this embodiment, pulleys 794 and 797 also function as the "engaging wheel 31" described in the previous embodiment.

[0207] The first drive mechanism 791 is provided with a brake mechanism 3c, and the second drive mechanism 792 is provided with a brake mechanism 3d. The brake mechanisms 3c and 3d have substantially the same configuration as the brake mechanisms 3a and 3b described above, and include a braking member 32, a biasing member 33, a braking member drive unit 34, and a fixing member (not shown).

[0208] In the power-off state, when the motors 793 and 796 and each braking member drive unit 34 are de-energized, the biasing force of the biasing member 33 causes the braking member 32 of the brake mechanism 3c to engage with the pulley 794, and the braking member 32 of the brake mechanism 3d to engage with the pulley 797. If the spline shaft 753 is relatively heavy, or if the end effector of the spline shaft 753 is gripping a relatively heavy object, the spline nut 751 and the ball screw nut 752 will have difficulty supporting the spline shaft 753, causing the spline shaft 753 to move downward. In response to this, the operation of the brake mechanisms 3c and 3d can prevent the spline shaft 753 from being displaced downward. Furthermore, the engagement can be released in the same manner as in the above embodiment.

[0209] Thus, the present invention is also applicable to SCARA robots. Specifically, the "first member" corresponds to the second arm 74, the "second member" corresponds to the work head 75, and the spline shaft 753 corresponds to the "part that is displaced in a direction including a vertical component."

[0210] 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.

[0211] Furthermore, the present invention may be a combination of any two or more features from the first to seventh embodiments. [Explanation of Symbols]

[0212] 1...Robot system, 2a...Brake mechanism, 3a...Brake mechanism, 3b...Brake mechanism, 3c...Brake mechanism, 3d...Brake mechanism, 4...Cushioning mechanism, 10...Robot, 20...Control device, 31...Engaging wheel, 32...Braking member, 33...Biasing member, 34...Braking member drive unit, 35...Fixing member, 36...Movement limit restricting member, 37...Movement limit restricting member, 38...Operating member, 39...Movement limit restricting member, 41...Base, 42...Rotating support part, 43...Movable part, 44...Biasing member, 45...Stopper, 52...Fixing part, 71...Base, 72...Robot arm, 73...First arm, 74... Second arm, 75...Working head, 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...Joint, 126...Joint, 126a...Shaft, 126b...Bearing part, 126c...Bearing part, 127...Joint, 128...Joint, 130...Link mechanism, 131...Link mechanism, 131a...Link, 131b...Link, 131c...Pivot, 131d...Pivot, 1 31h...Through hole, 132...Link mechanism, 132a...Link, 132b...Link, 132c...Link, 132d...Pivot, 132e...Pivot, 132f...Pivot, 132g...Pivot, 140...Drive unit, 150...Drive unit, 151...Motor, 151a...Second output shaft, 151b...Second housing, 151c...Mount, 152...Second power transmission section, 153...Second power transmission section, 153a...Input side rotation transmission member, 153b...Output side rotation transmission member, 153c...Annular member, 153s...Rotating shaft, 153t...Bearing section, 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...Drive unit, 161...Motor, 161a...Third output shaft, 161b...Third housing, 161c...Mount, 162...Third power transmission part, 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...Drive unit, 200...Robot arm, 201...Calculation unit, 202...Storage unit, 203...Communication unit, 300...Part, 311...Engaging projection, 311A...Engaging projection, 311B...Engaging projection, 321...Side surface, 322...Lower end surface, 341...Shaft, 342...Casing, 351...Base, 352...Installation part, 361...First restricting surface, 362...Second restricting surface, 371...Contact surface, 740...Arm base, 751...Sply 752...Ball screw nut, 753...Spline shaft, 791...First drive mechanism, 792...Second drive mechanism, 793...Motor, 794...Pulley, 795...Belt, 796...Motor, 797...Pulley, 798...Belt, A1...First axis, A2...Second axis, A3...Third axis, A31...Rotation axis, A32...Center axis, A4...Fourth axis, A5...Fifth axis, D1...First direction, D2...Second direction, D3...Third direction, E1...End effector, F1...Force, F2...Force, J1...First rotation axis, J2...Second rotation axis, J3...Third rotation axis, P1...Interface, P11...First plane, P12...Second plane,

Claims

1. First member and A second member is installed so as to be displaceable relative to the first member and has a portion that is displaceable in a direction including a vertical component, The system comprises a drive unit for driving the second member, The drive unit includes a motor, a power transmission unit that transmits the rotational force output by the motor to the second member, and a brake mechanism that restricts the vertical downward displacement of the part. The brake mechanism includes an engagement wheel provided on at least one of the motor and the power transmission unit, having a plurality of engagement protrusions along its outer circumference; a braking member that moves along the axis and engages with the engagement protrusions; a biasing member that biases the braking member along the axis in a direction that engages with the engagement protrusions; and a braking member drive unit that, by energizing, moves the braking member along the axis in a direction that separates it from the engagement wheel. When the motor and the braking member drive unit are energized, the braking member separates from the engaging wheel. The robot is characterized in that, when the power supply to the motor and the braking member drive unit is cut off, the engaging wheel is restricted from rotating in a first direction, which involves a vertical downward displacement of the part, as the braking member engages with the engaging projection, but it is still rotatable in the direction opposite to the first direction.

2. The robot according to claim 1, wherein the rotation axis of the engagement wheel and the axis of the braking member are in a torsional positional relationship.

3. The motor comprises a housing that houses a rotor and a stator, and an output shaft that protrudes from the housing and serves as the rotation axis of the rotor. The robot according to claim 1 or 2, wherein the engagement wheel is fixed to the output shaft.

4. The power transmission unit has an input-side rotation transmission member provided on the output shaft, The robot according to claim 3, wherein the engagement wheel is provided on the side of the input-side rotation transmission member opposite to the housing.

5. The robot according to claim 1 or 2, wherein the braking mechanism has a movement limit restricting member that restricts the movement limit of the braking member in the direction approaching the engagement wheel.

6. The robot according to claim 5, wherein the movement limit restricting member abuts against the opposite side of the engaging wheel via the axis of the braking member and has a contact surface inclined with respect to the axis.

7. The robot according to claim 1 or 2, wherein the motor and the braking member drive unit are energized and de-energized at synchronous timings.

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