Robot and robot system

Abstract

The invention relates to a robot and a robot system, and provides a detection method, a robot system, and a program to detect overload of a power transmission mechanism while seeking for simplification and cost reduction of device configuration. A robot is characterized by comprising: a base; and a robot arm which is connected to the base and includes a plurality of arms having joint parts provided with power transmission mechanisms, the power transmission mechanisms of the joint parts having planetary gear type first speed reducers, and the weight of the power transmission mechanism of one joint part closer to the fingertip side than the first speed reducers is lighter than the weight of the first speed reducers.

Description

Technical Field

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

[0002] A known robot has a robotic arm that includes a plurality of arms and joint portions that rotatably connect adjacent arms to each other. The robot drives the robotic arm to assume a desired posture to perform an operation on a workpiece. The robotic arm has a plurality of joint portions, and a joint mechanism is provided at each joint portion as a drive 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, a planetary gear type speed reducer is used as the speed reducer. Thereby, backlash between gears can be reduced, and thus the position accuracy of the robotic arm can be improved.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2009-222116

[0005] However, since the planetary gear type speed reducer is relatively heavy, for example, when a planetary gear type speed reducer is disposed at the distal end portion of the robotic arm, the inertial weight (moment of inertia) of the distal end portion of the robotic arm becomes large. In this case, in order to make the robotic arm perform agile movements, it is necessary to increase the amount of power supplied to the motors provided at the respective joint portions. In Patent Document 1, since this point is not considered, it is impossible to achieve agile movements while suppressing the amount of power supplied to the motors to achieve low power consumption. Summary of the Invention

[0006] The robot of the present invention includes: a base; and a robotic arm connected to the base, the robotic arm including a plurality of arms having joint portions each having a power transmission mechanism, the power transmission mechanism of the joint portion having a planetary gear type first speed reducer, and the weight of the power transmission mechanism of one joint portion closer to the fingertip side than the first speed reducer being lighter than the weight of the first speed reducer.

[0007] The robot system of the present invention includes: the robot of the present invention; a gantry on which the robot is provided; and a conveyor that sequentially conveys a plurality of work objects, and the robot continuously performs operations on the plurality of work objects conveyed by the conveyor. Brief Description of the Drawings

[0008] Figure 1 is a schematic configuration diagram of a robot system according to a first embodiment of the present invention.

[0009] Figure 2 is Figure 1 a cross-sectional view of a first speed reducer included in the robot shown.

[0010] Figure 3 is a representation of Figure 2 a perspective view of the internal structure of the first speed reducer shown.

[0011] Figure 4 is a perspective view of the internal structure of the first speed reducer included in the robot of the robot system according to the second embodiment of the present invention.

[0012] Figure 5 is a schematic configuration diagram of the robot system according to the third embodiment of the present invention.

[0013] Explanation of reference numerals

[0014] 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: Stand; 9: Conveyor; 21: Motor; 22: Power transmission mechanism; 23: First speed reducer; 23A: Gear train; 23B: Gear train; 31: Motor; 32: Power transmission mechanism; 33: Second speed reducer; 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: Gear 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. Detailed description of the embodiments

[0015] Hereinafter, the robot and the robot system of the present invention will be described in detail based on the embodiments shown in the drawings.

[0016] First embodiment

[0017] Figure 1 is a schematic configuration diagram of the robot system according to the first embodiment of the present invention. Figure 2 is Figure 1 a cross-sectional view of the first speed reducer included in the shown robot. Figure 3 is a representation of Figure 2 a perspective view of the internal structure of the first speed reducer shown.

[0018] It should be noted that Figure 1 the up - down direction in Figure 1 is the same as the vertical direction. The upper side in Figure 1 is also referred to as "upper", and the lower side is also referred to as "lower". For the robotic arm 72, the first arm 73, and the second arm 74, the

[0019] right side in

[0020] Figure 1 is referred to as the "base end portion", and the left side is referred to as the "front end portion".

[0021] In addition, in this specification, "vertical" not only includes the case where it is consistent with the vertical, but also includes the case where it is slightly inclined relative to the vertical, for example, within ±10°. In addition, in this specification, "parallel" not only includes the case where two objects are parallel, but also includes the case where they are slightly inclined from parallel, for example, within ±10°.

[0022] As shown in Figure 1 the robotic arm 7 has a base 71 and a robotic arm 72 rotatably connected to the base 71.

[0023] The base 71 is provided on the floor of a workroom such as a factory. The base 71 can also be provided at a location other than the floor, such as a wall surface, a ceiling, a later - described stand 8, a mobile stage, etc.

[0024] The control device 6 is provided inside the base 71. However, it is not limited to this configuration, and the control device 6 can also be provided at a location other than the base 71.

[0025] The robotic arm 72 has: a first arm 73, the base end portion of which is connected to the base 71 and rotates relative to the base 71 about a first rotation axis J1 along the vertical direction; and a second arm 74, the base end portion of which is connected to the front end portion of the first arm 73 and rotates relative to the first arm 73 about a second rotation axis J2 along the vertical direction.

[0026] At the front end of the second arm 74, an operation head 75 is provided. The operation head 75 has: a spline nut 751 and a ball screw nut 752, which are coaxially arranged at the front end of the second arm 74; and a spline shaft 753, which is inserted through the spline nut 751 and the ball screw nut 752. The spline shaft 753 can rotate relative to the second arm 74 about a third rotation axis J3 that is its central axis and extends in the vertical direction, and can move up and down in the direction along the third rotation axis J3.

[0027] An end effector 76 is assembled to the lower end of the spline shaft 753. The end effector 76 is detachable from and attachable to the spline shaft 753, and an end effector suitable for the target operation can be appropriately selected.

[0028] The robotic arm 72 has a first joint portion 2K, a second joint portion 3K, a third joint portion 4K, and a fourth joint portion 5K. The first joint portion from the base 71 side is the first joint portion 2K, the second joint portion from the base 71 side is the second joint portion 3K, the third joint portion from the base 71 side is the third joint portion 4K, and the fourth joint portion from the base 71 side is the fourth joint portion 5K.

[0029] Among 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 "fingertip side" joint portion. For example, the second joint portion 3K is located at a position closer to the fingertip side than the first joint portion 2K, and the third joint portion 4K and the fourth joint portion 5K are located at positions closer to the fingertip side than the first joint portion 2K and the second joint portion 3K, respectively.

[0030] In addition, regarding the third joint portion 4K and the fourth joint portion 5K, the fourth joint portion 5K can also be regarded as the third joint portion, and the third joint portion 4K can be regarded as the fourth joint portion.

[0031] The first joint portion 2K is a component that rotatably connects the base 71 and the first arm 73, and has a motor unit 2 that rotates the first arm 73 relative to the base 71 about the first rotation axis J1.

[0032] The second joint portion 3K is a component that rotatably connects the first arm 73 and the second arm 74, and has a motor unit 3 that rotates the second arm 74 relative to the first arm 73 about the second rotation axis J2.

[0033] The third joint portion 4K is a component that connects the spline shaft 753 to the second arm 74 so as to be able to move up and down along the third rotation axis J3, 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.

[0034] The fourth joint part 5K is a component that connects the spline shaft 753 to the second arm 74 in a manner that allows it to rotate around the third rotation axis J3, and is provided with a second drive mechanism 5 that rotates the spline nut 751 to cause the spline shaft 753 to rotate around the third rotation axis J3.

[0035] The motor unit 2 includes a motor 21 and a power transmission mechanism 22 with the motor 21 as the drive source. The motor 21 generates a driving force for rotating the first arm 73 relative to the base 71.

[0036] The motor unit 3 includes a motor 31 and a power transmission mechanism 32 with the motor 31 as the drive source. The motor 31 generates a driving force for rotating the second arm 74 relative to the first arm 73.

[0037] The first drive mechanism 4 includes a motor 41 and a power transmission mechanism 42 with the motor 41 as the drive source. The motor 41 generates a driving force for rotating the ball screw nut 752 to cause the spline shaft 753 to move up and down in the direction along the third rotation axis J3.

[0038] The second drive mechanism 5 includes a motor 51 and a power transmission mechanism 52 with the motor 51 as the drive source. The motor 51 generates a driving force for rotating the spline nut 751 to cause the spline shaft 753 to rotate around the third rotation axis J3.

[0039] There are no particular limitations on the motors 21, 31, 41, and 51. For example, servo motors such as AC servo motors and DC servo motors can be cited.

[0040] 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 housing that houses them. The stator is arranged along the inner circumference of the housing and has a winding such as a three-phase winding, for example. 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, and energization amount of each winding provided in the stator are controlled by the control device 6. As a result, the motors 21, 31, 41, and 51 rotate at the required timing, rotation direction, and speed, respectively.

[0041] The power transmission mechanism 22 includes a first speed reducer 23. The power transmission mechanism 32 includes a second speed reducer 33. The power transmission mechanism 42 includes a pulley and a belt (not shown). The power transmission mechanism 52 includes a pulley and a belt (not shown).

[0042] The first speed reducer 23 and the second speed reducer 33 are respectively planetary gear type speed reducers. As will be described later, since the first speed reducer 23 and the second speed reducer 33 have the same configuration except for the difference in weight, the following description will be given taking the first speed reducer 23 as a representative.

[0043] As Figure 2 andFigure 3 As shown in Figure 3 , the first speed reducer 23 has a frame 231, an internal gear 233, a sun gear 234, a plurality of (three in this embodiment) planetary gears 235, a gear carrier 236, an input shaft 237, and an output shaft 238. It should be noted that, in Figure 3 Figure 3 Figure 3 , for easy observation of the internal structure, the input shaft 237 and the output shaft 238 are illustrated thinner than their actual sizes. This also applies to Figure 4 Figure 4 Figure 4 . The first speed reducer 23 may also have an elastic support member outside the internal gear 233. The elastic support member has a strength such that the internal gear 233 can be deformed in the radial direction by the action of stress and its phase does not shift relative to the frame 231 in the circumferential direction.

[0044] As Figure 2 shown in Figure 2 , the frame 231 is a cylindrical housing and has the function of protecting each component inside it.

[0045] As Figure 3 shown in Figure 3 , the internal gear 233 is in 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 engage with the teeth 235A of each planetary gear 235.

[0046] The sun gear 234 has teeth 234A on its outer peripheral portion and is disposed inside the internal gear 233 at a position concentric 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 a bearing (not shown), for example. Although not shown, the motor 21 is directly or indirectly fixed to the base 71.

[0047] The three planetary gears 235 are arranged at equal angular intervals on the outer peripheral side of the sun gear 234 and 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 engage with the teeth 234A of the sun gear 234 and the internal teeth 233A of the internal gear 233. The diameters of the three planetary gears 235 and the number of teeth 235A are equal.

[0048] As Figure 2 and Figure 3 shown in Figure 2 and Figure 3 , the gear trains of the sun gear 234 and the three planetary gears 235 are arranged in a line on the same plane, that is, on a specified cross-section of the first speed reducer 23.

[0049] In addition, the types, shapes, etc. of the internal gear 233, the sun gear 234, and the planetary gears 235 are not particularly limited. 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 helical gears respectively.

[0050] The gear carrier 236 supports the planetary gear 235 in a manner that it can rotate about the axis O2 which is the central axis of the planetary gear 235. In the illustrated configuration, the gear carrier 236 has a shape formed by connecting the ends on the axis O1 side of three rod-shaped members arranged at 120° intervals, that is, a so-called star shape. However, it is not limited to this configuration, and the gear carrier 236 may also be formed by, for example, a frame-shaped member or a disk-shaped member.

[0051] An output shaft 238 is connected to the central portion of the gear 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).

[0052] 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 about the axis O1 in a specified direction. When the sun gear 234 rotates, each planetary gear 235 rotates about the axis O2 (self-rotates) and at the same time rotates about the axis O1 (revolves). Due to the revolution of each planetary gear 235 about the axis O1, the gear carrier 236 rotates about the axis O1, and thus the output shaft 238 rotates about 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 be rotated relative to the base 71 at a decelerated speed, and thus the rotational torque of the first arm 73 can be increased.

[0053] The speed ratio of the output shaft 238 to the input shaft 237, that is, the reduction ratio of the first speed reducer 23, is not particularly limited, and its preferred range will be described later.

[0054] It should be noted that although not shown, the input shaft of the second speed reducer 33 is connected to the 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 front end portion of the first arm 73.

[0055] Conversely, it may also be a configuration in which the input shaft of the second speed reducer 33 is connected to the motor 31 fixed to the front end portion of the first arm 73, and the output shaft of the second speed reducer 33 is fixed to the base end portion of the second arm 74.

[0056] And, by the same principle as above, the second arm 74 can rotate relative to the first arm 73.

[0057] The elasticity of the internal gear 233 is higher than that of the sun gear 234 and the planetary gear 235. However, it is sufficient that the elasticity of the internal gear 233 is higher than that of the planetary gear 235. Thereby, backlash can be suppressed, and thus the position accuracy of each part when the robotic arm 72 operates can be further improved.

[0058] The "elasticity" in this specification is determined not only by the material but also by the shape, etc., and refers to the property that the deformation generated when a force is applied to an object is restored when the applied force is removed. High elasticity means that the restoration speed is fast when the applied force is removed. That is, the "elasticity" in this specification is different from the properties determined by materials such as Young's modulus.

[0059] The frame 231, the internal gear 233, the sun gear 234, the planetary gears 235, the gear carrier 236, the input shaft 237, and the output shaft 238 are made of, for example, a metal material or a hard resin material.

[0060] In this way, the first speed reducer 23 includes: an annular 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 that mesh with both the internal gear 233 and the sun gear 234; and a gear carrier 236 that rotatably supports each planetary gear 235. The elasticity of the internal gear 233 is higher than that of the planetary gears 235. Thereby, backlash can be suppressed, and the position accuracy of each part of the robotic arm 72 can be further improved.

[0061] It should be noted that it is not limited to the above configuration. The internal gear 233 may have the same elasticity as the planetary gears 235 or may have lower elasticity than the planetary gears 235.

[0062] In addition, in the first speed reducer 23, the gear trains of the sun gear 234 and the plurality of planetary gears 235 are arranged in a row. In this way, by minimizing the number of gear trains, in the first speed reducer 23, the loss during torque transmission can be reduced. Further, the weight reduction of the first speed reducer 23 can be achieved.

[0063] In addition, the internal gear 233, the sun gear 234, and the planetary gears 235 are each preferably a helical gear. That is, the internal gear 233, the sun gear 234, and the planetary gears 235 are preferably helical gears. Thereby, compared with spur gears, the meshing area between the teeth can be increased, and since the surface pressure of the tooth surface decreases, relatively high torque can be transmitted smoothly and effectively.

[0064] It should be noted that it is not limited to the above configuration. The internal gear 233, the sun gear 234, and the planetary gears 235 may also be other types of gears such as spur gears.

[0065] 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.

[0066] 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.

[0067] The magnitude relationship between the reduction ratio V1 and the reduction ratio V2 is not particularly limited, but is preferably V1 ≥ V2, and more preferably 0.85 V1 ≥ V2.

[0068] Such reduction ratios V1 and V2 can be set by appropriately selecting the number of teeth of the teeth 234A and the teeth 235A.

[0069] Such planetary gear type reducers (first reducer 23, second reducer 33) have lower viscous resistance of grease and less torque loss than wave gear type reducers with the same maximum outer diameter. Therefore, when operating at the same rotation speed, by using a planetary gear type reducer, it is possible to perform agile operations while suppressing power consumption. However, the planetary gear type reducer is heavier than the wave gear type reducer with the same maximum outer diameter. Therefore, there is a tendency that the inertia moment of the robot arm 72 tends to increase.

[0070] In addition, it can be seen from the following equation (1) as the motion equation that when the inertia moment increases, the torque also increases, and the power consumption when the robot arm 72 is moved at the same speed increases. When the inertia moment is reduced, the acceleration is improved when the same torque is generated, and agile movement can be performed.

[0071] T (torque) = I (moment of inertia) × α (acceleration) (1)

[0072] Therefore, when a planetary gear type reducer is installed as in the robot 7, by reducing the inertia moment of the robot arm 72, it is possible to achieve both low power consumption and agile movement. In the prior art, no consideration or research has been conducted on the above technical problem, but in the present invention, the above technical problem can be solved by setting the following structure.

[0073] In the following description, the weight of the power transmission mechanism 22 of the first joint part 2K is referred to as weight G1, the weight of the power transmission mechanism 32 of the second joint part 3K is referred to as weight G2, the weight of the power transmission mechanism 42 of the third joint part 4K is referred to as weight G3, and the weight of the power transmission mechanism 52 of the fourth joint part 5K is referred to as weight G4.

[0074] The weight G1 of the power transmission mechanism 22 is set to the weight of the first reducer 23, the weight G2 of the power transmission mechanism 32 is set to the weight of the second reducer 33, the weight G3 of the power transmission mechanism 42 is set to the weight of the belt and the pulley, and the weight G4 of the power transmission mechanism 52 is set to the weight of the belt and the pulley.

[0075] In the robot 7, the weights satisfy G1 > G2 > G3 > G4. That is, it is configured such that the weight becomes lighter as it advances toward the fingertip side of the robotic arm 72. That is, the weights of 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 fingertip side than the first reduction gear 23, are lighter than the weight of the first reduction gear 23. By adopting such a configuration, even if a planetary gear type reduction gear is used as the first reduction gear 23, the inertial moment of the robotic arm 72 during operation can be suppressed. Therefore, low power consumption and agile movement can be achieved simultaneously.

[0076] It should be noted that the configuration is not limited to the above. It may also be a configuration that satisfies G1 ≥ G2 > G3 > G4, or a configuration that satisfies G1 > G2 ≥ G3 ≥ G4, or a configuration that satisfies G1 > G2 > G3 ≤ G4, or a configuration that satisfies G1 > G2 ≤ G3 > G4, or a configuration that satisfies G1 > G2 ≤ G3 ≤ G4. Further, it may also be a configuration that satisfies G1 > G2 ≥ G3 + G4, or a configuration that satisfies G1 ≥ G2 + G3, or a configuration that satisfies G1 ≥ G2 + G4.

[0077] The value of G2 / G1 is not particularly limited, and its preferred value will be described later.

[0078] As described above, the robot 7 includes: a base 71; and a robotic arm 72 connected to the base 71, including a plurality of arms, namely a first arm 73, a second arm 74, and a working head 75, having joint portions, namely a first joint portion 2K, a second joint portion 3K, a third joint portion 4K, and a fourth joint portion 5K, each of which has a power transmission mechanism 22, 32, 42, 52. In addition, the power transmission mechanism 22 of the first joint portion 2K has a planetary gear type first reduction gear 23, and the weight of the power transmission mechanism of one joint portion closer to the fingertip side than the first reduction gear 23 is lighter. More preferably, the weights of 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 fingertip side than the first reduction gear 23, are lighter than the weight of the first reduction gear 23. Thus, by using a planetary gear type reduction gear as the first reduction gear 23, sufficient torque transmission performance can be obtained, and the inertial moment of the robotic arm 72 during operation can be suppressed. Therefore, low power consumption and agile movement can be achieved simultaneously.

[0079] It should be noted that as the second reduction gear 33, it is not limited to a planetary gear type reduction gear, and other reduction gears such as an eccentric swing type or a harmonic gear type may also be used.

[0080] The power transmission mechanisms 42 and 52 are configured with belts and pulleys, but in the present invention, they are not limited thereto, and various speed reducers can also be used.

[0081] In addition, in the robot 7, it is preferable that the weight G1 > the weight G2 > the weight G3 + the weight G4. Thereby, the inertial moment of the robotic arm 72 during operation can be more effectively suppressed. Therefore, power consumption reduction and agile movement can be balanced at a higher level.

[0082] When the weight of the first speed reducer 23 is set as G1 and the weight of the second speed reducer 33 is set as 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, power consumption reduction and agile movement can be balanced at a higher level more effectively.

[0083] The robotic arm 72 includes: a first arm 73 connected to the base 71 via a first joint portion 2K, which is the first joint portion starting from the base 71 side, so as to be rotatable about a first rotation axis J1; a second arm 74 connected to the first arm 73 via a second joint portion 3K, which is the second joint portion starting from the base 71 side, so as to be rotatable about a second rotation axis J2 parallel to the first rotation axis J1; and a spline shaft 753 that moves along a third rotation axis J3 parallel to the first rotation axis J1 with respect to the second arm 74 via a third joint portion 4K, which is the third joint portion starting 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 that 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 fingertip side of the robotic arm 72 is reduced, and the root side, i.e., the base 71 side, can handle a high output torque. Therefore, a reduction in the inertial moment of the robotic arm 72 and an improvement in torque transmissibility can be balanced, and thus power consumption reduction and agile movement can be balanced at a higher level.

[0084] 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 modes A1 to A4 are preferable. The most preferable is mode A1, followed by mode A2, then mode A3, and then mode A4.

[0085] Mode A1

[0086] 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.

[0087] Mode A2

[0088] The first joint part 2K is a planetary gear type speed reducer, the second joint part 3K is a planetary gear type speed reducer, the third joint part 4K is a pulley, and the fourth joint part 5K is a pulley and a planetary gear type speed reducer.

[0089] Mode A3

[0090] The first joint part 2K is a planetary gear type speed reducer, the second joint part 3K is a harmonic gear type speed reducer, the third joint part 4K is a pulley, and the fourth joint part 5K is a pulley.

[0091] Mode A4

[0092] The first joint part 2K is a planetary gear type speed reducer, the second joint part 3K is a harmonic gear type speed reducer, the third joint part 4K is a pulley, and the fourth joint part 5K is a pulley and a planetary gear type speed reducer.

[0093] It should be noted that although not shown, in the case of a six-axis robot, as a combination of power transmission mechanisms of the first joint part, the second joint part, the third joint part, the fourth joint part, the fifth joint part, and the sixth joint part, the following modes B1 to B4 are preferred. The most preferred mode is B1, the second preferred mode is B2, and the third preferred mode is B4.

[0094] Mode B1

[0095] The first joint part is a planetary gear type speed reducer, the second joint part is a planetary gear type speed reducer, the third joint part is a planetary gear type speed reducer, the fourth joint part is a harmonic gear type speed reducer, the fifth joint part is a harmonic gear type speed reducer, and the sixth joint part is a harmonic gear type speed reducer.

[0096] Mode B2

[0097] The first joint part is a planetary gear type speed reducer, the second joint part is a harmonic gear type speed reducer, the third joint part is a harmonic gear type speed reducer, the fourth joint part is a harmonic gear type speed reducer, the fifth joint part is a harmonic gear type speed reducer, and the sixth joint part is a harmonic gear type speed reducer.

[0098] Mode B3

[0099] The first joint part is a planetary gear type speed reducer, the second joint part is a planetary gear type speed reducer, the third joint part is a planetary gear type speed reducer, the fourth joint part is a planetary gear type speed reducer, the fifth joint part is a planetary gear type speed reducer, and the sixth joint part is a harmonic gear type speed reducer.

[0100] It should be noted that in each joint part, it can also be a structure combined with a pulley and a belt.

[0101] Second Embodiment

[0102] Figure 4 It is a perspective view showing the internal structure of the first speed reducer provided in the robot of the robot system according to the second embodiment of the present invention.

[0103] Hereinafter, while referring to Figure 4 while explaining the robot of the robot system according to the second embodiment of the present invention, the following will be mainly described with respect to the differences from the first embodiment, and the description of the same matters will be omitted. It should be noted that, for the sake of easy understanding of the internal structure, the length in the vertical direction in the figure is exaggerated in Figure 4 the figure.

[0104] In the first speed reducer 23, the gear trains of the sun gear 234 and the plurality of planetary gears 235 are arranged in two rows. That is, as Figure 4 shown, a gear train 23A composed of the sun gear 234 and three planetary gears 235 is provided in a specified 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 in another cross section that is offset by a specified distance in the axial direction of the shaft O1.

[0105] Each of the gear trains 23A and 23B is arranged along the axial direction of the shaft O1. Figure 4 In Figure 4 the lower side is the input side (input shaft 237 side),

[0106] and the upper side 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.

[0107] The gear train 23A and the gear train 23B share a single internal gear 233. In addition, the gear 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 also serves as the output shaft of the gear train 23A and the input shaft of the gear train 23B. Thus, it is configured to be decelerated by the gear train 23A and also decelerated by the gear train 23B. Accordingly, in the present embodiment, the reduction ratio V1 of the first speed reducer 23 can be increased, for example, it can be set to be 1.3 times or more and 3.5 times or less of that in the first embodiment.

[0108] In the gear trains 23A and 23B, various conditions such as the diameters, tooth thicknesses of the sun gear 234 and the planet gears 235, the number of planet gears 235, and the number of teeth of the teeth 234A and 235A can be the same or different from each other. In particular, in the gear trains 23A and 23B, the respective reduction ratios can be the same or different.

[0109] It should be noted that, in the present embodiment, the case where the gear trains are arranged in two columns along the axial direction of the axis O1 has been described, but the present invention is not limited thereto, and it may also be three columns or more.

[0110] Third Embodiment

[0111] Figure 5 is a schematic configuration diagram of a robot system according to the third embodiment of the present invention.

[0112] Hereinafter, while referring to Figure 5 while explaining the third embodiment of the robot system of the present invention, hereinafter, the differences from the first embodiment and the second embodiment will be mainly described, and the description of the same matters will be omitted.

[0113] As Figure 5 shown, the robot system 1A includes a robot 7, a control device 6, a gantry 8, and a conveyor 9.

[0114] The robot 7 is a horizontal multi-joint robot suspended from the gantry 8, that is, a so-called hanging type SCARA robot. The configurations of the robot 7 and the control device 6 are the same as those described in the first embodiment.

[0115] The first speed reducer 23 of the robot 7 can also adopt any one of the structures in the first embodiment and the second embodiment.

[0116] The control device 6 controls the driving of each part of the robot 7.

[0117] The gantry 8 has a frame shape and has a top plate 81 at the upper part. The base 71 of the robot 7 is fixed to the top plate 81. In this case, the posture of the robot 7 is upside down compared with the first embodiment.

[0118] The second arm 74 has: a first part 741, which is connected to the first arm 73 and extends along the vertical direction; and a second part 742, which extends along the horizontal direction from the lower end of the first part 741. An operation head 75, a first driving mechanism 4, a second driving mechanism 5, etc. are mounted on the second part 742.

[0119] The conveyor 9 has along Figure 5The belt 91 that moves in the direction of the arrow in the figure and rollers (not shown) around which the belt 91 is wound. A motor (not shown) is connected to the rollers, and the belt 91 moves by the rotation of the rollers. A plurality of work objects W are placed on the upper surface of the belt 91.

[0120] The belt 91 moves along Figure 5 the direction of the arrow in the figure 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 above the belt 91.

[0121] The movement timing, movement speed, etc. of the belt 91 are controlled by the control device 6 or other control devices (not shown).

[0122] In the present embodiment, the first speed reducer 23 is also a planetary gear type speed reducer. The weights of 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 fingertip side than the first speed reducer 23, are lighter than the weight of the first speed reducer 23. Thus, even if a planetary gear type speed reducer is used as the first speed reducer 23, the inertial moment of the robotic arm 72 during operation can be suppressed. Therefore, it is possible to achieve both low power consumption and agile movement. When the robotic arm 72 can perform agile movement, the operation efficiency is improved, which contributes to the improvement of productivity.

[0123] In addition, since it is difficult for the planetary gear type speed reducer used for the first speed reducer 23 to generate vibration compared with other types of speed reducers, sufficient vibration damping performance can be ensured even if a frame 8 with a high-rigidity complex structure, a large-weight frame, or an expensive frame is not used as the frame 8. Therefore, the vibration damping performance of the robot system 1 is excellent, and it is possible to avoid large-sizing and suppress costs.

[0124] In this way, the robot system 1A includes: the robot 7; the frame 8 on which the robot 7 is provided; and the conveyor 9 that sequentially conveys a plurality of work objects W, and the robot 7 continuously performs operations on the plurality of work objects W conveyed by the conveyor 9. Thus, the robot 7 in the robot system 1A can obtain sufficient torque transmission performance by using a planetary gear type speed reducer as the first speed reducer 23 and suppress the inertial moment of the robotic arm 72 during operation. Therefore, it is possible to achieve both low power consumption and agile movement. In addition, the robot system 1A has excellent vibration damping performance, good operation efficiency, can suppress costs, and contributes to the improvement of productivity.

[0125] It should be noted that the robot system of the first embodiment is not limited to the case of continuously operating on the work object as in the third embodiment. For example, it can also be combined with a conveying device that conveys the work object batch by batch, that is, performs an operation on the work object once each time.

[0126] As described above, the robot and the robot system of the present invention have been described based on the illustrated embodiments, but the present invention is not limited to these, and the configuration of each part can be replaced with any configuration having the same function. In addition, any other components can be added.

Claims

1. A robot, characterized in that: The robot has: a base; and A robot arm connected to the base includes a plurality of arms having joints with a power transmission mechanism. The power transmission mechanism of the joint part has a first planetary gear type speed reducer. The weight of the power transmission mechanism of one of the joints located on the fingertip side relative to the first speed reducer is lighter than the weight of the first speed reducer.

2. The robot according to claim 1, characterized in that: The first speed reducer comprises: an annular internal gear; a sun gear disposed inside the internal gear and at a position concentric with the internal gear; and a plurality of planetary gears meshing with both the internal gear and the sun gear; and a gear carrier rotatably supporting each of the planetary gears, The elasticity of the internal gear is higher than the elasticity of the planetary gears.

3. The robot according to claim 2, characterized in that: The sun gear and the plurality of planetary gears are arranged in a row.

4. The robot according to claim 2, characterized in that: The gear rows of the sun gear and the plurality of planetary gears are arranged in a plurality of rows along a central axis direction of the internal gear.

5. The robot according to claim 2, characterized in that: The internal gear, the sun gear, and the planetary gears are helical gears, respectively.

6. The robot according to any one of claims 1 to 5, characterized in that: The robot arm comprises: a first arm, which is connected to the base in a manner that can rotate around a first rotation axis via a first joint portion that is the first joint portion from the base side; a second arm, which is connected to the first arm in a manner that can rotate around a second rotation axis parallel to the first rotation axis via a second joint portion that is the second joint portion from the base side; and an axis that moves along a third rotation axis parallel to the first rotation axis relative to the second arm via a third joint portion that is the third joint portion from the base side. The power transmission mechanism of the second joint portion includes a planetary gear type second speed reducer that is lighter than the first speed reducer. The power transmission mechanism of the third joint has a pulley and a belt.

7. The robot according to claim 6, characterized in that: When the weight of the first reducer is set to G1 and the weight of the second reducer is set to G2, G2 / G1 is 0.3 or more and 0.9 or less.

8. A robot system, characterized in that: The robot system comprises: The robot according to claim 1; A platform for setting up the robot; and Conveyors transport multiple work objects in sequence. The robot continuously performs work on the plurality of work objects conveyed by the conveyor.

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