Robot and robot system

Abstract

To provide a method of detection for detecting an overload on a power transmission device while simplifying a device configuration and reducing a cost, and to provide a robot system and a program.SOLUTION: A robot includes: a base; and a robot arm coupled to the base. The robot arm includes a plurality of arms having respective joints each of which has a power transmission mechanism. The power transmission mechanisms in the joints have a first reducer of an epicyclic gear type. The power transmission mechanism in one of the joints which is positioned on a farther side of the first reducer is lighter in weight than the first reducer.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] There is known a robot having a robot arm including a plurality of arms and joint portions that rotatably connect adjacent arms, and driving the robot arm to a desired posture to perform work on a workpiece. The robot arm has a plurality of joint portions, and a joint mechanism is installed in each joint portion as a driving portion for rotationally driving the arm. The joint mechanism has a motor as a drive source and a speed reducer for reducing the rotational speed of the motor.

[0003] For example, in Patent Document 1, an epicyclic gear type speed reducer is used as the speed reducer. Thereby, backlash between gears can be reduced, and the position accuracy of the robot arm can be improved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since an epicyclic gear type speed reducer is relatively heavy, for example, if an epicyclic gear type speed reducer is arranged at the tip of a robot arm, the inertial weight (inertia) of the tip of the robot arm becomes large. In this case, in order for the robot arm to perform a sensitive operation, it is necessary to increase the amount of electricity supplied to the motor of each joint portion. Since Patent Document 1 does not consider such a point, it is impossible to realize a sensitive operation while suppressing the amount of electricity supplied to the motor and achieving low power consumption.

Means for Solving the Problems

[0006] The robot of the present invention includes a base and a robot arm including a plurality of arms having joints connected to the base and including a power transmission mechanism. The power transmission mechanism of the joint has a planetary gear type first reduction gear. The power transmission mechanism of one of the joints on the hand side of the first reduction gear is lighter in weight than the first reduction gear.

[0007] The robot system of the present invention includes the robot of the present invention and a pedestal on which the robot is installed, and a conveyor for sequentially conveying a plurality of work objects. The robot continuously performs work on the plurality of work objects conveyed by the conveyor.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0009] Hereinafter, the robot and the robot system of the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

[0010] <First Embodiment> FIG. 1 is a schematic configuration diagram of a robot system according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of a first speed reducer provided in the robot shown in FIG. 1. FIG. 3 is a perspective view showing the internal structure of the first speed reducer shown in FIG. 2.

[0011] Note that the vertical direction in FIG. 1 coincides with the vertical direction, and the upper side in FIG. 1 is also referred to as "upper" and the lower side as "lower". For the robot arm 72, the first arm 73, and the second arm 74, the right side in FIG. 1 is referred to as the "base end portion" and the left side as the "tip end portion".

[0012] In addition, in this specification, "vertical" means not only the case where it coincides with the vertical, but also the case where it is inclined slightly with respect to the vertical, for example, within ±10°. Also, in this specification, "parallel" means not only the case where two objects coincide with each other, but also the case where they are inclined slightly from parallel, for example, within ±10°.

[0013] The robot system 1 shown in FIG. 1 includes a robot 7 and a control device 6 that controls the driving of each part of the robot 7.

[0014] The robot 7 in this embodiment is a scalar robot and is used, for example, in various operations such as holding, transporting, assembling, processing, painting, and inspecting workpieces such as electronic components (hereinafter these are collectively referred to as "operations"). However, the use and type of operations of the robot 7 are not particularly limited. Also, the robot 7 may be, for example, a 6-axis articulated robot, a dual-arm robot, etc. other than a scalar robot.

[0015] As shown in FIG. 1, the robot 7 has a base 71 and a robot arm 72 rotatably connected to the base 71.

[0016] The base 71 is installed on the floor surface of a workroom such as a factory. The base 71 may be installed at a location other than the floor surface, for example, on a wall surface, a ceiling, a gantry 8 described later, a moving table, etc.

[0017] Inside the base 71, a control device 6 is installed. However, it is not limited to this configuration, and the control device 6 may be installed at a location other than the base 71.

[0018] 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 along the vertical direction with respect 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 along the vertical direction with respect to the first arm 73.

[0019] A work head 75 is provided at the tip of the second arm 74. The work head 75 has a spline nut 751 and a ball screw nut 752 coaxially arranged 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 can rotate around a third rotation axis J3 which is its central axis and along the vertical direction with respect to the second arm 74, and can move up and down in the direction along the third rotation axis J3.

[0020] An end effector 76 is attached to the lower end of the spline shaft 753. The end effector 76 is detachable from the spline shaft 753, and an appropriate one suitable for the target work is selected as appropriate.

[0021] The robot arm 72 has a first joint part 2K, a second joint part 3K, a third joint part 4K, and a fourth joint part 5K. The first joint part from the base 71 side is the first joint part 2K, the second joint part from the base 71 side is the second joint part 3K, the third joint part from the base 71 side is the third joint part 4K, and the fourth joint part from the base 71 side is the fourth joint part 5K.

[0022] In the first joint portion 2K, the second joint portion 3K, the third joint portion 4K, and the fourth joint portion 5K, the joint portion with a larger number when counted from the base 71 is also referred to as the "tip side" joint portion. For example, the second joint portion 3K is located on the tip side of the first joint portion 2K, and the third joint portion 4K and the fourth joint portion 5K are located on the tip side of the first joint portion 2K and the second joint portion 3K, respectively.

[0023] Also, regarding the third joint portion 4K and the fourth joint portion 5K, the fourth joint portion 5K may be regarded as the third joint portion, and the third joint portion 4K may be regarded as the fourth joint portion.

[0024] The first joint portion 2K rotatably connects the base 71 and the first arm 73, and has a motor unit 2 that rotates the first arm 73 around the first rotation axis J1 with respect to the base 71.

[0025] The second joint portion 3K rotatably connects the first arm 73 and the second arm 74, and has a motor unit 3 that rotates the second arm 74 around the second rotation axis J2 with respect to the first arm 73.

[0026] The third joint portion 4K connects the spline shaft 753 to be vertically movable along the third rotation axis J3 with respect to the second arm 74, and has a first drive mechanism 4 that rotates the ball screw nut 752 to move the spline shaft 753 up and down in the direction along the third rotation axis J3.

[0027] The fourth joint portion 5K rotatably connects the spline shaft 753 to be rotatable around the third rotation axis J3 with respect to the second arm 74, and has a second drive mechanism 5 that rotates the spline nut 751 to rotate the spline shaft 753 around the third rotation axis J3.

[0028] The motor unit 2 includes a motor 21 and a power transmission mechanism 22 having the motor 21 as a drive source. The motor 21 generates a driving force for rotating the first arm 73 with respect to the base 71.

[0029] The motor unit 3 includes a motor 31 and a power transmission mechanism 32 that uses the motor 31 as a driving source. The motor 31 generates a driving force for rotating the second arm 74 with respect to the first arm 73.

[0030] The first drive mechanism 4 includes a motor 41 and a power transmission mechanism 42 that uses the motor 41 as a driving source. The motor 41 generates a driving force for rotating the ball screw nut 752 to move the spline shaft 753 up and down in the direction along the third rotation axis J3.

[0031] The second drive mechanism 5 includes a motor 51 and a power transmission mechanism 52 that uses the motor 51 as a driving source. The motor 51 generates a driving force for rotating the spline nut 751 to rotate the spline shaft 753 around the third rotation axis J3.

[0032] The motors 21, 31, 41, and 51 are not particularly limited, and examples include servo motors such as AC servo motors and DC servo motors.

[0033] Although not shown in the drawings, the motors 21, 31, 41, and 51 include a stator, a rotor that rotates inside the stator, and a case that houses them. The stator is arranged along the inner circumference of the case and has a winding such as a three-phase winding. The stator generates a magnetic field by energizing the winding, for example, by applying three-phase alternating current. In the motors 21, 31, 41, and 51, the energization pattern, energization timing, energization amount, etc. of each winding provided in the stator are controlled by the control device 6. Thereby, the motors 21, 31, 41, and 51 rotate at desired timings, rotation directions, and speeds, respectively.

[0034] The power transmission mechanism 22 has a first speed reducer 23. The power transmission mechanism 32 has a second speed reducer 33. The power transmission mechanism 42 has pulleys and belts (not shown). The power transmission mechanism 52 has pulleys and belts (not shown).

[0035] The first speed reducer 23 and the second speed reducer 33 are each a planetary gear type speed reducer. Since the first speed reducer 23 and the second speed reducer 33 have the same configuration except for different weights as will be described later, the first speed reducer 23 will be typically described below.

[0036] As shown in FIGS. 2 and 3, the first speed reducer 23 includes a frame 231, an internal gear 233, a sun gear 234, a plurality of, in this embodiment, three planetary gears 235, a carrier 236, an input shaft 237, and an output shaft 238. In FIG. 3, for easy viewing of the internal structure, the input shaft 237 and the output shaft 238 are shown thinner than actual. The same applies to FIG. 4. The first speed reducer 23 may have an elastic support member outside the internal gear 233. The elastic support member enables radial deformation of the internal gear 233 due to the action of stress and has a strength such that the phase does not shift with respect to the frame 231 in the circumferential direction.

[0037] As shown in FIG. 2, the frame 231 is a cylindrical casing and has a function of protecting each member inside it.

[0038] As shown in FIG. 3, the internal gear 233 has a ring shape or a cylindrical shape centered on the axis O1 and has internal teeth 233A on its inner peripheral portion. The internal teeth 233A mesh with the teeth 235A of each planetary gear 235.

[0039] The sun gear 234 has teeth 234A on its outer peripheral portion and is arranged inside the internal gear 233 and at a concentric position with the internal gear 233. The sun gear 234 is connected to the input shaft 237 and rotates around the axis O1. The input shaft 237 is connected to the rotating shaft of the motor 21 via, for example, a bearing (not shown). The motor 21 is fixed to the base 71 directly or indirectly although not shown.

[0040] The three planetary gears 235 are arranged at equal angular intervals on the outer peripheral side of the sun gear 234 and on the inner peripheral side of the internal gear 233. Each planetary gear 235 has teeth 235A on its outer peripheral portion, and the teeth 235A mesh with the teeth 234A of the sun gear 234 and the internal teeth 233A of the internal gear 233. The three planetary gears 235 are equal in diameter and the number of teeth 235A.

[0041] As shown in FIGS. 2 and 3, the gear trains of the sun gear 234 and the three planetary gears 235 are provided in a single row on the same plane, that is, on a predetermined cross-section of the first speed reducer 23.

[0042] Also, the types, forms, etc. of the internal gear 233, the sun gear 234, and the planetary gears 235 are not particularly limited, and in the illustrated configuration, they are spur gears respectively. However, in the present invention, the internal gear 233, the sun gear 234, and the planetary gears 235 are preferably herringbone gears respectively.

[0043] The carrier 236 rotatably supports the planetary gears 235 around the axis O2, which is the central axis of the planetary gears 235. In the illustrated configuration, the carrier 236 has a shape formed by connecting three rod-shaped members arranged at 120° intervals at their end portions on the axis O1 side, so-called star shape. However, the present invention is not limited to this configuration, and the carrier 236 may be composed of, for example, a frame-shaped member or a disk-shaped member.

[0044] An output shaft 238 is connected to the central portion of the carrier 236. The output shaft 238 is fixed to the base end portion of the first arm 73 via, for example, a bearing (not shown).

[0045] The rotational force transmitted from the motor 21 is transmitted to the sun gear 234 via the input shaft 237, and the sun gear 234 rotates in a predetermined direction around the axis O1. When the sun gear 234 rotates, each planetary gear 235 rotates (revolves) around the axis O1 while rotating (rotating on its own axis) around the axis O2. Due to the revolution of each planetary gear 235 around the axis O1, the carrier 236 rotates around the axis O1, and the output shaft 238 rotates around the axis O1. As a result, the rotation of the output shaft 238 is decelerated by the planetary gears 235 and is slower than the rotation of the input shaft 237. Therefore, the rotational speed of the input shaft 237 is decelerated and output from the output shaft 238. As a result, the first arm 73 can rotate with respect to the base 71 at a decelerated speed, and the rotational torque of the first arm 73 can be increased.

[0046] The rotation speed ratio of the output shaft 238 with respect to the input shaft 237, that is, the reduction ratio of the first speed reducer 23, is not particularly limited, but the preferable range will be described later.

[0047] Although not shown in the figure, the input shaft of the second speed reducer 33 is connected to a motor 31 fixed to the base end portion of the second arm 74, and the output shaft of the second speed reducer 33 is fixed to the tip end portion of the first arm 73.

[0048] Conversely, the input shaft of the second speed reducer 33 may be connected to a motor 31 fixed to the tip end portion of the first arm 73, and the output shaft of the second speed reducer 33 may be fixed to the base end portion of the second arm 74.

[0049] And, based on the same principle as above, the second arm 74 can rotate with respect to the first arm 73.

[0050] The internal gear 233 is more elastic than the sun gear 234 and the planetary gears 235. However, it is sufficient that the internal gear 233 is more elastic than the planetary gears 235. Thereby, backlash can be suppressed, and the position accuracy of each part during the operation of the robot arm 72 can be further improved.

[0051] As used herein, "elasticity" is determined not only by the material but also by the shape and the like, and refers to the property that the deformation occurring when a force is applied to an object returns to its original state when the application of the force is released. A high elasticity means a high speed of returning to the original state when the application of the force is released. That is, "elasticity" as used herein is different from the property determined by the material such as Young's modulus.

[0052] The frame 231, the internal gear 233, the sun gear 234, the planetary gears 235, the carrier 236, the input shaft 237, and the output shaft 238 are made of, for example, a metal material or a hard resin material.

[0053] Thus, the first speed reducer 23 includes a ring-shaped internal gear 233, a sun gear 234 disposed inside the internal gear 233 and concentric with the internal gear 233, a plurality of planetary gears 235 meshing with both the internal gear 233 and the sun gear 234, and a carrier 236 rotatably supporting each planetary gear 235. The internal gear 233 has higher elasticity than the planetary gears 235. Thereby, backlash can be suppressed and the position accuracy of each part of the robot arm 72 can be further improved.

[0054] Note that the present invention is not limited to the above configuration, and the internal gear 233 may have the same elasticity as the planetary gears 235, or may have lower elasticity than the planetary gears 235.

[0055] Also, in the first speed reducer 23, the gear trains of the sun gear 234 and the plurality of planetary gears 235 are provided in one row. Thus, by minimizing the number of gear trains, in the first speed reducer 23, the loss during torque transmission can be reduced. Furthermore, the weight of the first speed reducer 23 can be reduced.

[0056] Further, the internal gear 233, the sun gear 234, and the planetary gear 235 are each preferably a spline gear. That is, the internal gear 233, the sun gear 234, and the planetary gear 235 are preferably helical gears. Thereby, the meshing area between the teeth can be increased compared to spur gears, and the surface pressure on the tooth surface is reduced, so that a relatively high torque can be transmitted smoothly and efficiently.

[0057] Note that the present invention is not limited to the above configuration, and the internal gear 233, the sun gear 234, and the planetary gear 235 may be other types of gears such as spur gears, for example.

[0058] The reduction ratio V1 of the first speed reducer 23 is preferably 1 / 100 or more and 1 / 3 or less, and more preferably 1 / 50 or more and 1 / 3 or less.

[0059] The reduction ratio V2 of the second speed reducer 33 is preferably 1 / 100 or more and 1 / 3 or less, and more preferably 1 / 50 or more and 1 / 3 or less.

[0060] The magnitude relationship between the reduction ratio V1 and the reduction ratio V2 is not particularly limited, but preferably V1≧V2, and more preferably 0.85V1≧V2.

[0061] Such reduction ratios V1 and V2 can be set by appropriately selecting the number of teeth of the teeth 234A and 235A.

[0062] Such planetary gear type speed reducers (the first speed reducer 23 and the second speed reducer 33) have lower grease viscous resistance and less torque cross compared to a wave gear type speed reducer having the same maximum outer diameter. Therefore, when operating at the same rotational speed, using a planetary gear type speed reducer enables sensitive operation while suppressing power consumption. However, a planetary gear type speed reducer is heavier compared to a wave gear type speed reducer having the same maximum outer diameter. For this reason, the moment of inertia of the robot arm 72 tends to increase.

[0063] Also, as is clear from the following formula (1) which is the equation of motion, when the moment of inertia increases, the torque also increases, and the power consumption increases when operating the robot arm 72 at the same speed. When the moment of inertia is reduced, when generating the same torque, the acceleration is improved and a nimble operation becomes possible. T (torque) = I (moment of inertia) × α (acceleration) … (1)

[0064] Therefore, in the case of mounting a planetary gear type speed reducer like the robot 7, by devising so that the moment of inertia of the robot arm 72 is reduced, it is possible to achieve both low power consumption and nimble operation. Conventionally, no consideration or devising has been made regarding the above problems, but in the present invention, the above problems can be solved by adopting the following configuration.

[0065] In the following description, the weight of the power transmission mechanism 22 of the first joint portion 2K is referred to as weight G1, the weight of the power transmission mechanism 32 of the second joint portion 3K is referred to as weight G2, the weight of the power transmission mechanism 42 of the third joint portion 4K is referred to as weight G3, and the weight of the power transmission mechanism 52 of the fourth joint portion 5K is referred to as weight G4.

[0066] The weight G1 of the power transmission mechanism 22 is taken as the weight of the first speed reducer 23, the weight G2 of the power transmission mechanism 32 is taken as the weight of the second speed reducer 33, the weight G3 of the power transmission mechanism 42 is taken as the weight of the belt and pulley, and the weight G4 of the power transmission mechanism 52 is taken as the weight of the belt and pulley.

[0067] In the robot 7, the weights satisfy G1 > G2 > G3 > G4. That is, the weight becomes lighter as it goes toward the tip side of the robot arm 72. That is, the power transmission mechanisms 32, 42, and 52 of the second joint portion 3K, the third joint portion 4K, and the fourth joint portion 5K, which are joint portions on the tip side rather than the first speed reducer 23, are lighter in weight than the first speed reducer 23. By adopting such a configuration, even if a planetary gear type speed reducer is used as the first speed reducer 23, the moment of inertia of the robot arm 72 during operation can be suppressed. Therefore, it is possible to achieve both low power consumption and agile operation.

[0068] Note that the configuration is not limited to the above, and a configuration that satisfies G1 ≧ G2 > G3 > G4 may be used, a configuration that satisfies G1 > G2 ≧ G3 ≧ G4 may be used, a configuration that satisfies G1 > G2 > G3 ≦ G4 may be used, a configuration that satisfies G1 > G2 ≦ G3 > G4 may be used, or a configuration that satisfies G1 > G2 ≦ G3 ≦ G4 may be used. Further, a configuration that satisfies G1 > G2 ≧ G3 + G4 may be used, a configuration that satisfies G1 ≧ G2 + G3 may be used, or a configuration that satisfies G1 ≧ G2 + G4 may be used. The value of G2 / G1 is not particularly limited, but its preferable value will be described later.

[0069] As described above, the robot 7 includes a base 71, and a robot arm 72 including a plurality of arms having a first joint portion 2K, a second joint portion 3K, a third joint portion 4K, and a fourth joint portion 5K which are joint portions connected to the base 71 and include power transmission mechanisms 22, 32, 42, and 52, and a working head 75. Further, the power transmission mechanism 22 of the first joint portion 2K has a planetary gear type first speed reducer 23, and the power transmission mechanism of one joint portion on the hand tip side of the first speed reducer 23 is light in weight. More preferably, the power transmission mechanisms 32, 42, and 52 of the second joint portion 3K, the third joint portion 4K, and the fourth joint portion 5K, which are joint portions on the hand tip side of the first speed reducer 23, are lighter in weight than the first speed reducer 23. Thereby, by using a planetary gear type speed reducer as the first speed reducer 23, sufficient torque transmission performance can be obtained, and the moment of inertia of the robot arm 72 during operation can be suppressed. Therefore, it is possible to achieve both low power consumption and agile operation.

[0070] Note that the second speed reducer 33 is not limited to a planetary gear type speed reducer, and for example, a speed reducer such as an eccentric swing type or a harmonic gear type may be used.

[0071] Although the power transmission mechanism 42 and the power transmission mechanism 52 have a configuration having a belt and a pulley, the present invention is not limited thereto, and various speed reducers may be used.

[0072] Also, in the robot 7, it is preferable to satisfy the weight G1 > weight G2 > weight G3 + weight G4. Thereby, the moment of inertia of the robot arm 72 during operation can be more effectively suppressed. Therefore, it is possible to achieve both low power consumption and agile operation at a higher level.

[0073] When the weight of the first speed reducer 23 is G1 and the weight of the second speed reducer 33 is G2, G2 / G1 is preferably 0.3 or more and 0.9 or less, and more preferably 0.4 or more and 0.8 or less. Thereby, it is possible to more effectively achieve both low power consumption and agile operation at a higher level.

[0074] The robot arm 72 is connected to the base 71 so as to be rotatable about a first rotation axis J1 via a first joint portion 2K which is the first joint portion from the base 71 side, and a first arm 73 which is rotatably connected to the first arm 73 about a second rotation axis J2 parallel to the first rotation axis J1 via a second joint portion 3K which is the second joint portion from the base 71 side. A spline shaft 753 which is a shaft that moves along a third rotation axis J3 parallel to the first rotation axis J1 via a third joint portion 4K which is the third joint portion from the base 71 side. The power transmission mechanism 32 of the second joint portion 3K has a planetary gear type second speed reducer 33 which is lighter in weight than the first speed reducer 23, and the power transmission mechanism 42 of the third joint portion 4K has a pulley and a belt. Thereby, the weight on the tip side of the robot arm 72 is reduced, and the base side, that is, the base 71 side can cope with a high output torque. Therefore, it is possible to obtain a good balance between reduction of the moment of inertia of the robot arm 72 and improvement of torque transmission performance, and it is possible to achieve both low power consumption and agile operation at a higher level.

[0075] As combinations of the power transmission mechanisms of the first joint portion 2K, the second joint portion 3K, the third joint portion 4K, and the fourth joint portion 5K, the following patterns A1 to A4 are preferable. Pattern A1 is the most preferable, pattern A2 is the next preferable, pattern A3 is the next preferable, and pattern A4 is the next preferable.

[0076] (Pattern A1) The first joint portion 2K is a planetary gear type speed reducer, the second joint portion 3K is a planetary gear type speed reducer, the third joint portion 4K is a pulley, and the fourth joint portion 5K is a pulley.

[0077] (Pattern A2) The first joint portion 2K is a planetary gear type speed reducer, the second joint portion 3K is a planetary gear type speed reducer, the third joint portion 4K is a pulley, and the fourth joint portion 5K is a pulley and a planetary gear type speed reducer.

[0078] (Pattern A3) The first joint 2K is a planetary gear type reducer, the second joint 3K is a harmonic gear type reducer, the third joint 4K is a pulley, and the fourth joint 5K is a pulley.

[0079] (Pattern A4) The first joint 2K is a planetary gear type reducer, the second joint 3K is a harmonic gear type reducer, the third joint 4K is a pulley, and the fourth joint 5K is a pulley and a planetary gear type reducer.

[0080] Although not shown in the drawings, in the case of a six-axis robot, as combinations of the power transmission mechanisms of the first joint, the second joint, the third joint, the fourth joint, the fifth joint, and the sixth joint, the following patterns B1 to B4 are preferable. Pattern B1 is the most preferable, pattern B2 is the next preferable, and pattern B4 is the next preferable.

[0081] (Pattern B1) The first joint is a planetary gear type reducer, the second joint is a planetary gear type reducer, the third joint is a planetary gear type reducer, the fourth joint is a harmonic gear type reducer, the fifth joint is a harmonic gear type reducer, and the sixth joint is a harmonic gear type reducer.

[0082] (Pattern B2) The first joint is a planetary gear type reducer, the second joint is a harmonic gear type reducer, the third joint is a harmonic gear type reducer, the fourth joint is a harmonic gear type reducer, the fifth joint is a harmonic gear type reducer, and the sixth joint is a harmonic gear type reducer.

[0083] (Pattern B3) The first joint is a planetary gear type reducer, the second joint is a planetary gear type reducer, the third joint is a planetary gear type reducer, the fourth joint is a planetary gear type reducer, the fifth joint is a planetary gear type reducer, and the sixth joint is a harmonic gear type reducer. In addition, in each joint, a combination of a pulley and a belt may be used.

[0084] <Second Embodiment> FIG. 4 is a perspective view showing the internal structure of a first speed reducer provided in a robot of a robot system according to a second embodiment of the present invention.

[0085] Hereinafter, the robot of the robot system according to the second embodiment of the present invention will be described with reference to FIG. 4. Hereinafter, the description will focus on the differences from the first embodiment, and the description of the same matters will be omitted. Note that, in order to make the internal structure easy to understand, in FIG. 4, the length in the vertical direction in the figure is exaggeratedly illustrated.

[0086] In the first speed reducer 23, two rows of gear trains of the sun gear 234 and a plurality of planetary gears 235 are provided. That is, as shown in FIG. 4, a gear train 23A composed of the sun gear 234 and three planetary gears 235 is provided on a predetermined cross section of the first speed reducer 23, and a gear train 23B composed of the sun gear 234 and three planetary gears 235 is provided on another cross section that is displaced by a predetermined distance in the axial direction of the shaft O1.

[0087] The gear trains 23A and 23B are arranged side by side along the axial direction of the shaft O1. The lower side in FIG. 4 is the input side (input shaft 237 side), and the upper side in FIG. 4 is the output side (output shaft 238 side). The gear train 23A is arranged on the input side, and the gear train 23B is arranged on the output side.

[0088] The gear trains 23A and 23B share one internal gear 233. In addition, the carrier 236 of the gear train 23A is connected to the sun gear 234 of the gear train 23B via a shaft-like connecting portion 239. That is, the connecting portion 239 serves as both the output shaft of the gear train 23A and the input shaft of the gear train 23B. For this reason, the configuration is such that deceleration is performed by the gear train 23A and further deceleration is performed by the gear train 23B. Thereby, in the present embodiment, the reduction ratio V1 of the first speed reducer 23 can be increased, for example, to be 1.3 times or more and 3.5 times or less compared to the first embodiment.

[0089] As described above, in the first speed reducer 23, the gear trains of the sun gear 234 and the plurality of planetary gears 235 are provided in a plurality of rows, in this embodiment two rows, along the direction of the axis O1 which is the central axis of the internal gear 233. Thereby, the reduction ratio V1 of the first speed reducer 23 can be increased with a simple structure, and a relatively high torque can be stably output. Further, the weight of the first speed reducer 23 can be increased, for example, it can be made easier to satisfy the weight G1 > weight G2.

[0090] For the gear trains 23A and 23B, various conditions such as the diameters, tooth thicknesses of the sun gear 234 and the planetary gears 235, the number of planetary gears 235, and the number of teeth of the teeth 234A and 235A may be the same or different respectively. In particular, for the gear trains 23A and 23B, the respective reduction ratios may be the same or different.

[0091] In addition, in this embodiment, the case where the gear trains are provided in two rows along the axial direction of the axis O1 has been described, but the present invention is not limited to this, and three or more rows may be used.

[0092] <Third Embodiment> FIG. 5 is a schematic configuration diagram of a robot system according to the third embodiment of the present invention.

[0093] Hereinafter, the third embodiment of the robot system of the present invention will be described with reference to FIG. 5. Hereinafter, the description will focus on the differences from the first embodiment and the second embodiment, and the description of the same matters will be omitted.

[0094] As shown in FIG. 5, the robot system 1A includes a robot 7, a control device 6, a gantry 8, and a conveyor 9.

[0095] The robot 7 is a horizontal articulated robot suspended and installed on the gantry 8, which is a so-called overhead scalar robot. The configurations of the robot 7 and the control device 6 are the same as those described in the first embodiment.

[0096] For the first speed reducer 23 of the robot 7, the structures of either the first embodiment or the second embodiment can be used. The control device 6 controls the driving of each part of the robot 7.

[0097] The gantry 8 has a frame shape and has a top plate 81 above. The robot 7 has a base 71 fixed to the top plate 81. In this case, the posture of the robot 7 is the opposite of that in the first embodiment.

[0098] The second arm 74 is connected to the first arm 73 and has a first portion 741 extending in the vertical direction and a second portion 742 extending horizontally from the lower end of the first portion 741. The second portion 742 is mounted with a work head 75, a first drive mechanism 4, a second drive mechanism 5, etc.

[0099] The conveyor 9 has a belt 91 that moves in the direction of the arrow in FIG. 5 and a roller (not shown) around which the belt 91 is wound. A motor (not shown) is connected to the roller, and the belt 91 moves due to the rotation of the roller. A plurality of work objects W are placed on the upper surface of the belt 91.

[0100] The belt 91 moves in the direction of the arrow in FIG. 5 and sequentially conveys the work objects W at a predetermined interval. The robot 7 continuously performs a predetermined operation on the work objects W sequentially conveyed from a position above the belt 91.

[0101] The movement timing, movement speed, etc. of the belt 91 are controlled by the control device 6 or another control device (not shown).

[0102] Also in this embodiment, the first speed reducer 23 is a planetary gear type speed reducer, and the power transmission mechanisms 32, 42, and 52 of the second joint portion 3K, the third joint portion 4K, and the fourth joint portion 5K, which are joint portions closer to the hand tip side than the first speed reducer 23, are lighter in weight than the first speed reducer 23. Thereby, even if a planetary gear type speed reducer is used as the first speed reducer 23, the moment of inertia of the robot arm 72 during operation can be suppressed. Therefore, it is possible to achieve both low power consumption and agile operation. When the robot arm 72 can perform agile operation, the work efficiency is improved, contributing to the improvement of productivity.

[0103] In addition, the planetary gear type speed reducer used for the first speed reducer 23 is less likely to generate vibration compared to other types of speed reducers. Therefore, even if a complex structure with high rigidity, a large weight, or an expensive one is not used as the pedestal 8, sufficient vibration damping performance can be ensured. Therefore, the robot system 1 has excellent vibration damping performance, can avoid enlargement, and can suppress costs.

[0104] As described above, the robot system 1A includes the robot 7, the pedestal 8 on which the robot 7 is installed, and the conveyor 9 that sequentially conveys a plurality of work objects W. The robot 7 continuously performs work on the plurality of work objects W conveyed by the conveyor 9. Thereby, the robot 7 in the robot system 1A can obtain sufficient torque transmission performance and suppress the moment of inertia of the robot arm 72 during operation by using a planetary gear type speed reducer as the first speed reducer 23. Therefore, it is possible to achieve both low power consumption and agile operation. In addition, the robot system 1A has excellent vibration damping performance, good work efficiency, can suppress costs, and contributes to the improvement of productivity.

[0105] Note that the robot system of the first embodiment is not limited to the case of performing work on a work object in a continuous manner as in the third embodiment. For example, it may be combined with a conveying device that conveys in a so-called batch manner, performing work on the work object once at a time.

[0106] As described above, the robot and the robot system of the present invention have been described based on the illustrated embodiments. However, the present invention is not limited thereto, and the configuration of each part can be replaced with any configuration having the same function. Further, any other components may be added.

Explanation of Reference Numerals

[0107] 1... Robot system, 1A... Robot system, 2... Motor unit, 2K... First joint part, 3... Motor unit, 3K... Second joint part, 4... First drive mechanism, 4K... Third joint part, 5... Second drive mechanism, 5K... Fourth joint part, 6... Control device, 7... Robot, 8... Mount, 9... Conveyor, 21... Motor, 22... Power transmission mechanism, 23... First reduction gear, 23A... Gear train, 23B... Gear train, 31... Motor, 32... Power transmission mechanism, 33... Second reduction gear, 41... Motor, 42... Power transmission mechanism, 51... Motor, 52... Power transmission mechanism, 71... Base, 72... Robot arm, 73... First arm, 74... Second arm, 75... Working head, 76... End effector, 81... Top plate, 91... Belt, 231... Frame, 233... Internal gear, 233A... Internal teeth, 234... Sun gear, 234A... Teeth, 235... Planet gear, 235A... Teeth, 236... Carrier, 237... Input shaft, 238... Output shaft, 239... Connecting part, 741... First part, 742... Second part, 751... Spline nut, 752... Ball screw nut, 753... Spline shaft, J1... First rotation axis, J2... Second rotation axis, J3... Third rotation axis, O1... Axis, O2... Axis, W... Work object

Claims

1. A base, A robot arm including a plurality of arms having joints connected to the base and including a power transmission mechanism, The power transmission mechanism of the joint has a planetary gear type first speed reducer, A robot characterized in that the power transmission mechanism of one joint on the hand tip side of the first speed reducer is lighter in weight than the first speed reducer.

2. The first speed reducer includes a ring-shaped internal gear, a sun gear disposed inside the internal gear and concentric with the internal gear, a plurality of planetary gears meshing with both the internal gear and the sun gear, and a carrier rotatably supporting each planetary gear. The robot according to claim 1, wherein the internal gear is more elastic than the planetary gear.

3. The robot according to claim 2, wherein the gear trains of the sun gear and the plurality of planetary gears are provided in a single row.

4. The robot according to claim 2, wherein the gear trains of the sun gear and the plurality of planetary gears are provided in a plurality of rows along the central axis direction of the internal gear.

5. The robot according to claim 2, wherein the internal gear, the sun gear, and the planetary gear are all spur gears.

6. The robot arm includes a first arm rotatably connected to the base about a first rotation axis via a first joint which is the first joint from the base side, a second arm rotatably connected to the first arm about a second rotation axis parallel to the first rotation axis via a second joint which is the second joint from the base side, and a shaft moving along a third rotation axis parallel to the first rotation axis via a third joint which is the third joint from the base side with respect to the second arm. The power transmission mechanism of the second joint has a planetary gear type second speed reducer lighter in weight than the first speed reducer. The robot according to any one of claims 1 to 5, wherein the power transmission mechanism of the third joint has a pulley and a belt.

7. When the weight of the first speed reducer is G1 and the weight of the second speed reducer is G2, The robot according to claim 6, wherein G2 / G1 is 0.3 or more and 0.9 or less.

8. The robot according to claim 1, A pedestal on which the robot is installed, A conveyor for sequentially conveying a plurality of work objects, The robot is a robot system characterized by continuously performing operations on the plurality of work objects conveyed by the conveyor.

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