Drive device and robot equipped with drive device

Abstract

This robot comprises: a drive device which has formed therein a hollow part that extends in a direction along the axis of rotation; and an optical cable which is disposed so as to pass through the interior of the hollow part. The robot is equipped with a first supporting member and a second supporting member that support the optical cable. The first supporting member is fixed to a member that remains still during driving of the drive device. The second supporting member is fixed to a member that rotates during driving of the drive device. The first supporting member and the second supporting member are formed so as to support the optical cable on the axis of rotation.

Description

Drive unit and robot equipped with drive unit

[0001] The present invention relates to a drive unit and a robot equipped with the drive unit.

[0002] A robotic device comprises a work tool that performs work and a robot that moves the work tool. The robot can change the position and posture of the work tool by driving components such as an arm. The robot is equipped with a drive unit including an electric motor for moving the components. For example, a drive unit for moving each component is installed at the joint of the robot. The drive unit can rotate one component relative to another component.

[0003] It is known that umbilical members, such as power cables and signal lines for driving a drive unit, are arranged inside a component such as a robot arm (see, for example, Japanese Patent Application Laid-Open No. 2008-18475). In this case, a through-hole is formed in the drive unit arranged at the joint. The umbilical member is inserted through the through-hole and arranged from the internal space of one component to the internal space of another component. For example, a pipe is arranged along the rotation axis, and the umbilical member, such as a power cable, is arranged inside the pipe (see, for example, Japanese Patent Application Laid-Open No. 2015-211999).

[0004] JP 2015-211999 A JP 2008-18475 A

[0005] In a robot joint, one component rotates relative to another, causing the relative angle between the components to change. When a filament is placed inside a component of the robot, the direction of extension of the filament changes as the component rotates. As a result, a force in a predetermined direction is applied to the filament placed in the joint. For example, a bending force or a twisting force acts on the filament.

[0006] In conventional technology, electric wires have been used as communication lines for transmitting control signals. However, when electric wires are used as communication lines, there is a problem that the electrical signals are susceptible to noise. Also, electric wires can generate electromagnetic noise. Therefore, optical cables can be used as communication lines instead of electric wires. By using optical cables as communication lines, they do not become a source of electromagnetic noise and are less susceptible to noise from the surrounding area. However, optical cables can be damaged by forces applied depending on the movement of the robot's components.

[0007] A robot according to an aspect of the present disclosure includes a drive device that rotates a second component of the robot around a rotation axis relative to a first component of the robot. The robot includes a member that defines a cavity extending in a direction along the rotation axis. The robot includes an optical cable that is arranged to pass through the interior of the cavity. The robot includes a first support member that is arranged on one axial side of the cavity and supports the optical cable, and a second support member that is arranged on the opposite axial side of the cavity and supports the optical cable. The first support member is fixed to a member that remains stationary when driven by the drive device. The second support member is fixed to a member that rotates when driven by the drive device. The first support member and the second support member are configured to support the optical cable approximately on the rotation axis. The first support member and the second support member are configured such that when driven by the drive device, the second support member rotates relative to the first support member, causing the optical cable to twist between the first support member and the second support member.

[0008] A drive device according to an aspect of the present disclosure rotates two different members relatively around a rotation axis and has a cavity extending in a direction along the rotation axis. The drive device includes an electric motor that generates rotational force. The drive device includes: a first support member disposed on one axial side of the cavity and supporting an optical cable so that the optical cable passes through the cavity; and a second support member disposed on the opposite axial side of the cavity and supporting the optical cable. The first support member is fixed to a component of the drive device that remains stationary when the electric motor is driven. The second support member is fixed to a component of the drive device that rotates when the electric motor is driven. The first support member and the second support member are configured to support the optical cable approximately on the rotation axis. The first support member and the second support member are configured such that, when the electric motor is driven, the second support member rotates relative to the first support member, causing the optical cable to twist between the first support member and the second support member.

[0009] According to aspects of the present disclosure, it is possible to provide a drive device that suppresses damage to an optical cable used as a communication line, and a robot equipped with the drive device.

[0010] 1 is a perspective view of a robot according to an embodiment. FIG. 2 is a schematic cross-sectional view of a joint in which a first driving unit according to an embodiment is arranged. FIG. 3 is a schematic partial cross-sectional view of the first driving unit when viewed from the side of the second support member. FIG. 4 is a perspective view of an optical cable according to an embodiment. FIG. 5 is a schematic cross-sectional view of an optical cable. FIG. 6 is a schematic cross-sectional view of a joint in which a second driving unit according to an embodiment is arranged. FIG. 7 is a schematic cross-sectional view of a joint in which a third driving unit according to an embodiment is arranged. FIG. 8 is a schematic cross-sectional view of a joint in which a fourth driving unit according to an embodiment is arranged. FIG. 9 is a schematic partial cross-sectional view of the fourth driving unit when viewed from the side of the second support member. FIG. 10 is a schematic partial cross-sectional view of a fifth driving unit according to an embodiment when viewed from the side of the second support member. FIG. 11 is a schematic partial cross-sectional view of a sixth driving unit according to an embodiment when viewed from the side of the second support member.

[0011] 1 to 11, a description will be given of a driving device and a robot equipped with the driving device according to an embodiment. The driving device of this embodiment rotates one component of the robot around a predetermined rotation axis relative to the other component. An optical cable is arranged as a communication line for transmitting information to the driving device or for receiving information from the driving device.

[0012] FIG. 1 is a perspective view of a robot according to this embodiment. The robot 1 according to this embodiment is a multi-joint robot including a plurality of joints 10a to 10f. The robot 1 according to this embodiment is a collaborative robot that can work in collaboration with a worker. The collaborative robot is configured so that the movement of the robot 1 is restricted when a predetermined external force acts on the robot 1. For example, the collaborative robot is configured to detect that a worker has come into contact with the robot and stop the robot 1.

[0013] The robot 1 includes a plurality of rotatable components at joints 10a to 10f. Each component is configured to rotate around drive axes J1 to J6 as a rotation axis. The drive devices of this embodiment are disposed inside the joints 10a to 10f to drive the components of the robot 1.

[0014] The robot 1 includes a base 14 fixed to an installation surface and a swivel base 13 supported by the base 14. The swivel base 13 rotates relative to the base 14 about a drive axis J1. The upper arm 12 of the robot 1 rotates relative to the swivel base 13 about a drive axis J2. The forearm 11 of the robot 1 rotates relative to the upper arm 12 about a drive axis J3. Furthermore, the forearm 11 rotates about a drive axis J4 that is parallel to the direction in which the forearm 11 extends. The robot 1 includes a wrist 15 supported by the forearm 11. The wrist 15 rotates about a drive axis J5. The wrist 15 also includes a flange 16 that rotates about a drive axis J6. A work tool is fixed to the flange 16 depending on the task to be performed by the robot device.

[0015] The robot 1 of this embodiment includes a base 14, a swivel base 13, an upper arm 12, a forearm 11, and a wrist 15 as components of the robot 1. The robot of this embodiment has six drive shafts, but is not limited to this. A robot that changes its position and posture using any mechanism can be used.

[0016] 2 shows a schematic cross-sectional view of a joint including a first drive unit according to the present embodiment. Referring to FIGS. 1 and 2, the first drive unit 2 is disposed in the joint 10b. The first drive unit 2 rotates the upper arm arm 12, which serves as a second component, around a drive axis J2, which serves as a rotation axis 71, relative to a swivel base 13, which serves as a first component.

[0017] In this embodiment, a driving device that drives the upper arm 12 disposed at the joint 10b will be described as an example, but the present invention is not limited to this. The driving device of this embodiment can be disposed at a joint that rotates a second component of the robot around a rotation axis relative to a first component of the robot. In other words, the driving device of this embodiment can be disposed at any joint and rotate any component.

[0018] The drive unit 2 includes an electric motor 21 that generates a rotational force and a reducer 22 that amplifies the torque output by the electric motor 21. The drive unit 2 is driven by the electric motor 21. The housing of the reducer 22 is fixed to the housing 12a of the upper arm arm 12. The electric motor 21 is fixed to the reducer 22. When the electric motor 21 is driven, the reducer 22 and the electric motor 21 rotate around the rotation axis 71 together with the housing 12a of the upper arm arm 12.

[0019] The drive unit 2 includes a torque sensor 23 that detects the torque output from the drive unit 2. In this embodiment, the torque sensor 23 is composed of an inner ring, an outer ring, and multiple spoke-shaped detectors connecting the inner and outer rings. The outer ring of the torque sensor 23 is fixed to the housing 13a of the swivel base 13, and the inner ring is fixed to the output section of the reducer 22. When the electric motor 21 is driven, the housing 13a of the swivel base 13 and the torque sensor 23 remain stationary and do not rotate. The torque sensor 23 detects the torque around the rotation shaft 71 when the drive unit 2 is driven. The robot control device receives a signal related to the torque via a communication line. The robot control device subtracts a moment related to the robot's own weight and a moment related to the robot's motion from the torque detected by the torque sensor. The calculated moment corresponds to an external force acting on the robot.

[0020] The robot control device can limit the movement of the robot when the external force is greater than a predetermined judgment value. The drive device in this embodiment includes a torque sensor, but this is not limited to this. The drive device does not necessarily have to include a torque sensor. In this case, the output shaft of the reducer can be fixed to the housing 13a of the swivel base 13.

[0021] The drive unit 2 of this embodiment includes a protective tube 24 as a member constituting a cavity 24a extending in a direction along the rotation shaft 71. The space inside the protective tube 24 corresponds to the cavity 24a penetrating from one end face to the other end face of the drive unit 2. The member constituting the cavity 24a in this embodiment is disposed in the drive unit 2. The electric motor 21 has a cavity 21a extending in a direction along the rotation shaft 71. The reducer 22 has a cavity 22a extending in a direction along the rotation shaft 71. The torque sensor 23 has a cavity 23a extending in a direction along the rotation shaft 71. In this embodiment, these cavities 21a, 22a, and 23a have approximately the same inner diameter and are disposed coaxially. The protective tube 24 is disposed inside the cavities 21a, 22a, and 23a so as to penetrate the cavities 21a, 22a, and 23a. In this embodiment, the protective tube 24 is disposed in the joint 10b of the robot 1. The cavity 24a is formed coaxially with the rotation shaft 71, but this is not limiting. The axis of the cavity 24a may be spaced apart from the rotation shaft 71. Furthermore, the member that forms the cavity may be a member that is disposed outside the drive device. In other words, the cavity through which the optical cable is inserted does not have to be formed inside the drive device. For example, the cavity may be formed in the housing of a component of the robot.

[0022] In this embodiment, the protective tube 24 is made of resin. A wire can be inserted through the protective tube 24. In this embodiment, a linear member is referred to as a wire. In this embodiment, at least a portion of the wire is laid inside the housing of a component of the robot 1, such as an arm. The protective tube 24 is arranged to protect the wire arranged inside. A flange portion at the tip of the protective tube 24 is fixed to the inner ring portion of the torque sensor 23. The protective tube 24 maintains a stationary state when the electric motor 21 is driven. Note that the protective tube 24 does not necessarily have to be arranged. For example, the cavities 21a, 22a, and 23a may form a cavity that penetrates the drive device. In this case, the electric motor 21, the reducer 22, and the torque sensor 23 correspond to the members that form the cavity.

[0023] In the robot 1 of this embodiment, a drive unit is provided for each of the joints 10a to 10f. That is, one drive unit is provided for each joint. The multiple drive units of the robot 1 of this embodiment are configured to perform serial communication with each other. The drive unit 2 includes a driver 25 that controls the electricity supplied to the electric motor 21. The driver 25 includes, for example, an inverter, and converts direct current electricity into alternating current and supplies it to the electric motor 21. A signal for controlling the electric motor 21 is sent from the robot's control device to the driver 25.

[0024] In this embodiment, an optical cable 51 is used as the communication line connected to the driver 25, instead of an electric wire. That is, the optical cable 51 is used as the signal line of the drive unit 2. The optical cable 51 connects the drive units arranged at the respective joints. Alternatively, the optical cable 51 connects the drive units arranged at the joints with the robot's control unit. For example, an electrical signal can be converted into an optical signal, and the signal can be transmitted or received via the optical cable.

[0025] In this embodiment, any communication protocol that allows serial communication via an optical cable can be used. For example, a communication protocol that performs optical communication using a method similar to that of an industrial Ethernet (registered trademark) such as EtherCAT (registered trademark) or a field bus such as RS-485 can be used. Note that the communication method of the robot drive device is not limited to serial communication, and any method can be used. For example, a configuration that performs parallel communication via an optical cable is also acceptable.

[0026] In this embodiment, the robot control device is connected to the driver of the drive unit arranged on drive axis J1 via an optical cable. The driver of the drive unit arranged on drive axis J1 is connected to the driver 25 of the drive unit 2 arranged on drive axis J2 shown in FIG. 2 via an optical cable. Furthermore, the driver 25 of the drive unit 2 arranged on drive axis J2 is connected to the driver of the drive unit arranged on drive axis J3 via an optical cable. In this way, adjacent drive units are connected to each other via optical cables up to the drive unit arranged on drive axis J6.

[0027] The information communicated via the optical cable includes the position command, rotational speed command, current command, and voltage command for the motor of each drive unit. In other words, it includes information about the electricity supplied to the motor. The information about the electricity of each driver is generated by the robot's control device and received by each drive unit via the communication line.

[0028] The information communicated via the optical cable may also include information detected by a sensor disposed on the robot. For example, the information may include information about the position or speed detected by a rotational position detector (encoder) attached to the electric motor, and information about the current detected by a current detector disposed in the driver. Alternatively, the information may include information about the torque output from a torque sensor. Information about the outputs of these sensors is included in the signal output from the driver. The information communicated via the optical cable includes at least one of the above-mentioned multiple pieces of information.

[0029] The driver 25 of the drive unit 2 includes a communication device 26 that transmits and receives information communicated via an optical cable. In this embodiment, the communication device 26 is disposed in the drive unit 2. Referring to FIG. 2 , the driver of the drive unit disposed on the drive shaft J1 is connected to an optical cable 50. The optical cable 50 is connected to an optical cable 51 via a connector 66. The optical cable 51 passes through the hollow portion 24a inside the protective tube 24. The optical cable 51 is connected to an optical cable 53 extending from the communication device 26 of the driver 25 via the connector 66.

[0030] Furthermore, another optical cable 54 extending from the communication device 26 of the driver 25 is connected to the optical cable 52 via a connector 66. The optical cable 52 is connected to the driver of the drive device disposed on the drive axis J3. In this way, by employing an optical cable as a communication line and arranging a communication device for optical communication in the robot 1, optical communication can be implemented.

[0031] The optical cable of this embodiment includes two optical fibers as at least two signal lines. One signal line transmits a signal from the drive device arranged on the drive shaft J1 to the drive device arranged on the drive shaft J6. The other signal line transmits a signal from the drive device arranged on the drive shaft J6 to the drive device arranged on the drive shaft J1.

[0032] A power cable for supplying power to drive the electric motor 21 is connected to the driver 25 of the drive unit 2. In the first drive unit 2, the power cable for supplying electricity to the electric motor 21 can be laid, for example, outside the housing of the robot. In this way, the power cable does not have to be arranged inside the components of the robot.

[0033] The signal from the driver of the drive device arranged on the drive shaft J1 includes a signal for driving the electric motor 21 of the drive shaft J2. For example, the signal includes a signal for controlling an inverter that generates a current to be supplied to the electric motor 21. The driver 25 of the drive device 2 supplies electricity to the electric motor 21 based on the signal for driving the electric motor 21.

[0034] Furthermore, the driver 25 of the drive device 2 includes in the output signal information relating to the outputs of the sensors arranged in the drive device 2. For example, the driver 25 includes in the signal output from the driver 25 at least one of information relating to the output of the torque sensor 23, the output of the rotational position detector, and the output of the current detector.

[0035] The communication device 26 in this embodiment is disposed inside the housing 12a of the upper arm 12, which is the second component of the robot 1. By disposing the communication device 26 inside the housing of the component of the robot, it is possible to prevent the robot from becoming large.

[0036] 3 shows a partial cross-sectional view of the second support member of the first drive unit. Referring to FIGS. 2 and 3, the drive unit 2 in this embodiment includes a first support member 31 and a second support member 32 that support the optical cable 51. Each of the first support member 31 and the second support member 32 is formed to support the optical cable 51 at one point. The first support member 31 is fixed to a member that remains stationary when the drive unit 2 is driven. In this example, the first support member 31 is fixed to the housing 13a of the swivel base 13. Alternatively, the first support member 31 may be fixed to the inner ring portion of the torque sensor 23.

[0037] The second support member 32 is fixed to a member that rotates when the drive device 2 is driven. In this example, the second support member 32 is fixed to the housing of the electric motor 21. When the electric motor 21 is driven, the second support member 32 rotates around the rotation axis 71 together with the housing of the electric motor 21, as shown by arrow 91. Note that the second support member 32 may also be fixed to the housing 12a.

[0038] 2 and 3 show a state in which the robot is stopped at a reference position. The second support member 32 is disposed in the same phase as the first support member 31. The first support member 31 and the second support member 32 support a wire such as the optical cable 51 so that the wire bends in the section between the first support member 31 and the second support member 32.

[0039] In this embodiment, the wire is fixed to the first support member 31 and the second support member 32 in the same manner. The first support member 31 has a fixing portion 31a at its tip. The fixing portion 31a has a plate-like shape. An optical cable 51 is fixed to the fixing portion 31a with a cable tie 41. Similarly, the second support member 32 has a fixing portion 32a at its tip. The fixing portion 32a is formed in a plate-like shape. The optical cable 51 is fixed to the fixing portion 32a with a cable tie 42. The cable ties 41, 42 may be made of an elastic material such as nylon. Note that, in this embodiment, the fixing portions 31a, 32a are formed so as to face the outside of the protective tube 24 in the direction of the rotation shaft 71, but this is not limited to this embodiment. The fixing portions may also be formed so as to face the inside of the protective tube 24 in the direction of the rotation shaft 71. Furthermore, the fixing portions may be disposed inside the protective tube by bending each of the support members toward the inside of the protective tube.

[0040] FIG. 4 shows a perspective view of an optical cable according to this embodiment. FIG. 5 shows a cross-sectional view of the optical cable according to this embodiment. FIG. 5 is a cross-sectional view of an optical cable 51 cut along a plane perpendicular to the direction in which the cable extends. In this embodiment, an optical fiber is referred to as a linear member including one core wire. For example, the core wire includes a core as a linear light propagation portion, and the core is covered with resin. The core can be formed of, for example, quartz glass or a plastic such as acrylic resin. Furthermore, the optical fiber can have a structure in which the core wire is further covered with a sheath such as resin. In this embodiment, an optical cable is referred to as a communication line including at least one optical fiber. For example, the optical cable can have a structure in which multiple optical fibers are integrated with resin.

[0041] 4 and 5, optical cable 51 according to the present embodiment has a structure in which two optical fibers 51 a and 51 b are fixed to each other and integrated together. Optical fibers 51 a and 51 b are fixed to each other by sheath 51 c formed of resin. Optical fibers 51 a and 51 b are fixed so as to extend parallel to each other.

[0042] In this manner, the optical cable 51 in this embodiment has a structure in which a pair of optical fibers 51 a, 51 b are fixed to each other. In this embodiment, in order to perform serial communication, a communication line is required to transmit information to the drive device of the drive shaft J6 at the tip of the robot 1, and a communication line is required to transmit information from the drive shaft J6 at the tip to the drive shaft J1 and the robot control device.

[0043] The optical cable 51 of this embodiment is composed of two optical fibers 51a, 51b, which is the minimum number required for serial communication. Furthermore, because the two optical fibers 51a, 51b are fixed and integrated with each other, the diameter of the optical cable 51 can be reduced. As a result, the drive unit 2 can be made smaller. Alternatively, the proportion of the optical cable 51 in the cavity 24a is reduced, allowing other filaments to be placed in the cavity 24a. This configuration also improves the workability when laying the optical cable inside a component such as a robot arm. While the optical cable of this embodiment is composed of two optical fibers, this is not limiting. The optical cable may include any number of optical fibers.

[0044] In this embodiment, a buffer material 61 is wrapped around the optical cable 51 to protect the optical cable 51. The buffer material 61 can be made of an elastic material such as sponge or rubber. The buffer material 61 can be arranged, for example, in an area fixed to the fixing portions 31a and 32a by the cable ties 41 and 42. Alternatively, referring to FIG. 2 , the buffer material 61 can be arranged around the optical cable 51 in a section from a connector 66 arranged on one axial side of the protective tube 24 to a connector 66 arranged on the other axial side of the protective tube 24. Alternatively, the buffer material need not be arranged around the optical cable.

[0045] Incidentally, the inventors conducted research and experiments into damage to optical cables caused by various movements, and as a result, they discovered that optical cables are relatively weak against bending movements but relatively strong against twisting movements. That is, they found that optical cables are stronger against twisting movements around the axis of the optical cable than movements that change the direction of extension. Based on this characteristic, the inventors came up with a structure, as in the present embodiment, in which bending movements of the optical cable are suppressed and twisting movements occur preferentially.

[0046] In the state shown in Fig. 2, the first support member 31 and the second support member 32 are arranged in the same phase. In the state shown in Fig. 2, the second support member 32 is arranged at a predetermined reference position. The cross-sectional shape of the filament in the first support member 31 and the cross-sectional shape of the filament in the second support member 32 are plane-symmetrical with respect to the central plane 73 of the cavity 24a in the direction of the axis (rotation axis 71). Referring to Figs. 2 and 3, the optical cable 51 is fixed to the fixing portions 31a and 32a so that the optical fibers 51a and 51b are aligned horizontally. The optical cable 51 is arranged on the rotation axis 71.

[0047] In this embodiment, the first support member 31 is disposed on one axial side of the cavity 24a. In particular, the first support member 31 is disposed on one side with respect to the axial center plane 73 of the cavity 24a of the protective tube 24. The second support member 32 is disposed on the opposite side of the axial side of the cavity 24a. In particular, the second support member 32 is disposed on the opposite side of the first support member 31 with respect to the axial center plane 73 of the cavity 24a. The first support member 31 and the second support member 32 are disposed on opposite sides of the center plane 73 of the cavity 24a. It is preferable that the first support member 31 and the second support member 32 are disposed near the outlets on both sides of the cavity 24a.

[0048] The first support member 31 and the second support member 32 are formed to support the optical cable 51 substantially on the rotation axis 71. Here, "supported substantially on the rotation axis" means supported on or near the rotation axis. That is, the first support member 31 and the second support member 32 are formed to support the optical cable 51 on or near the rotation axis 71. For example, referring to FIG. 3 , it is preferable that the rotation axis 71 is located within the area of ​​the optical cable 51 when the fixing portions 31 a, 32 a are cut at the fixing portions 31 a, 32 a. Alternatively, for example, it is preferable that the center of gravity of the cross-sectional shape of the optical cable 51 is located in an area that is half the inner diameter of the protective tube 24.

[0049] When the electric motor 21 is driven, the second support member 32 rotates relative to the first support member 31. The second support member 32 rotates together with the electric motor 21 and the upper arm arm 12 around the rotation axis 71 in the direction indicated by the arrow 91. Even when the upper arm arm 12 rotates, the fixed part 32a remains on or near the rotation axis 71.

[0050] As the fixed portion 32a rotates around the rotation axis 71, the movable portion of the optical cable 51 is twisted between the first support member 31 and the second support member 32. The first support member 31 and the second support member 32 support the optical cable 51 at or near the rotation axis 71, and therefore bending of the optical cable 51 can be suppressed. Since the optical cable 51 is resistant to damage caused by twisting, damage to the optical cable 51 can be suppressed.

[0051] Furthermore, in this embodiment, when the phase of the first support member 31 and the phase of the second support member 32 are the same, the optical cable 51 is supported so as to bend between the first support member 31 and the second support member 32. Therefore, when the electric motor 21 is driven and the optical cable 51 is twisted, it is possible to prevent a strong tension from being applied to the optical cable 51 in the extending direction.

[0052] 6 shows an enlarged schematic cross-sectional view of a joint including a second drive unit according to this embodiment. The second drive unit 3 differs from the first drive unit 2 in the position of the support member. In the second drive unit 3, the first support member 33 is fixed to the inner circumferential surface of the protective tube 24. An optical cable 51 is fixed to the first support member 33 at a fixing portion 33a with a cable tie 43. The first support member 33 is fixed to a member that remains stationary when the electric motor 21 is driven. The first support member 33 supports the optical cable 51 on or near the rotation shaft 71.

[0053] The second support member 34 is fixed to an arm that rotates when the electric motor 21 is driven. The second support member 34 is fixed to the inner surface of the housing 12a of the upper arm arm 12. The optical cable 51 is fixed to the second support member 34 at a fixing portion 34a with a cable tie 44. The second support member 34 is formed so as to support the optical cable 51 on or near the rotation shaft 71, even when the electric motor 21 is driven. The second drive unit 3 can also suppress bending of the optical cable 51 when the electric motor 21 is driven, thereby suppressing damage to the optical cable 51.

[0054] The first support member can be fixed to a member that remains stationary even when the electric motor 21 is driven, and therefore may be fixed, for example, to the inner surface of the housing 13a of the swivel base 13. On the other hand, the second support member can be fixed to a member that rotates when the electric motor 21 is driven. For this reason, for example, if the electric motor includes an encoder, the second support member may be fixed to the housing of the encoder.

[0055] 7 shows an enlarged schematic cross-sectional view of a joint including a third drive unit according to this embodiment. The third drive unit 4 has a different orientation relative to the components of the robot 1 compared to the first drive unit 2 and the second drive unit 3. In the third drive unit 4, the electric motor 21 and the reducer 22 are fixed to the housing 13a of the swivel base 13. Meanwhile, the torque sensor 23 is fixed to the housing 12a of the upper arm 12.

[0056] In the third drive unit 4, the torque sensor 23 connected to the output shaft of the reducer 22 rotates together with the upper arm 12 when the electric motor 21 is driven. On the other hand, the electric motor 21 and the reducer 22 are maintained stationary when the electric motor 21 is driven. In the third drive unit 4, the first support member 35 is fixed to the housing of the electric motor 21. An optical cable 51 is fixed to the fixing portion 35a of the first support member 35 with a cable tie 45. The second support member 36 is fixed to the inner ring portion of the torque sensor 23. The optical cable 51 is fixed to the fixing portion 36a of the second support member 36 with a cable tie 46. Each of the fixing portions 35a, 36a is formed to support the optical cable 51 on or near the rotation shaft 71.

[0057] The driver 25, which includes the communication device 26, is disposed inside the housing 13a of the swivel base 13, which is the first component. The driver 25 is connected to the driver of the drive device disposed on the drive axis J1 via optical cables 50 and 53. The driver 25 is then connected to the driver of the drive device disposed on the drive axis J3 via optical cables 54, 51, and 52. An optical cable 51 is inserted into the hollow portion 24a inside the protective tube 24.

[0058] In the third drive unit 4, when the electric motor 21 is driven, the fixed portion 36a of the second support member 36 rotates around the rotation axis 71. The fixed portion 35a of the first support member 35 is stationary. As a result, a twisting motion occurs in the optical cable 51. This can suppress bending motion of the optical cable 51, thereby suppressing damage to the optical cable 51. Note that in the third drive unit 4, the first support member may be fixed to the housing 13a of the swivel base 13. Also, the second support member may be fixed to the housing 12a of the upper arm 12.

[0059] Fig. 8 shows an enlarged schematic cross-sectional view of a joint including a fourth drive unit according to this embodiment. Fig. 9 shows a schematic partial cross-sectional view of the second support member of the fourth drive unit according to this embodiment. In the drive units 2, 3, and 4 described above, a single optical cable 51 is disposed in the hollow portion 24a inside the protective tube 24, but this is not limiting. Multiple umbilical members can be disposed inside the components of the robot. Multiple umbilical members other than the optical cable 51 can be inserted into the hollow portion of the drive unit so as to pass through the joint.

[0060] 8 and 9 , the fourth drive unit 5 differs from the first drive unit 2 in that a first support member 29 and a second support member 30 support multiple wire bodies. The support members 29, 30 each have multiple wire bodies secured to them with cable ties 39, 40. The wire bodies in this embodiment include a power cable 56, which supplies electricity to the driver 25 to drive the electric motor 21; an air supply pipe 57, which supplies pressurized air to drive the work tool; an electric wire 58, which supplies backup electricity to the rotational position detector (encoder); and a communication cable 59, which transmits signals to drive the work tool. The communication cable 59 is an electric cable, and is therefore included in the category of electric wires. The wire bodies are not limited to this form. Any movable linear body that is resistant to twisting or bending can be used.

[0061] The cable tie 40 is arranged to surround the multiple wires. The cable tie 40 secures the multiple wires together to the fixing portion 30a so that they are bundled together. Each wire is arranged to pass through the hollow portion 24a inside the protective tube 24. In the first support member 29, when the second support member 30 is arranged in the same phase as the first support member 29, the multiple wires are arranged to be symmetrical about the central plane 73 with respect to the arrangement of the wires in the second support member 30. In the section between the fixing portions 29a and 30a, the multiple wires are supported so as to be flexible. In the section between the fixing portions 29a and 30a, the multiple wires are not fixed and are arranged so as to be freely deformable. In the section between the fixing portions 29a and 30a, the wires move away from each other when the drive device is driven, thereby suppressing damage to the wires.

[0062] The first support member 29 and the second support member 30 support the optical cable 51 near the rotation axis 71. The first support member 29 and the second support member 30 support the electric power cable 56, the backup electric cable 58, and the communication cable 59 as electric wires at positions farther from the rotation axis 71 than the optical cable 51.

[0063] Here, the inventors conducted research and experiments on damage to electric wires and found that, when a bundle of electric wires is subjected to a reciprocating torsional motion, the closer the bundle of electric wires is located to the rotation axis, the shorter the lifespan of the electric wires before the conductors break due to metal fatigue. In the fourth drive unit 5, the lifespan of the electric wires can be extended by arranging the electric wires at a position farther from the rotation axis 71. Also, in the fourth drive unit 5, the optical cable 51 is arranged near the rotation axis 71. As a result, in the fourth drive unit 5, the lifespan of the optical cable 51, the power cable 56, the electric wires 58, and the communication cable 59 can be extended.

[0064] In this way, in the fixing parts 29a and 30a, it is preferable to arrange the optical cable 51 on or near the rotation axis 71, and arrange the wires other than the optical cable 51, such as electric wires, around the optical cable 51. Alternatively, in the cross section of a bundle of multiple wires, the optical cable 51 can be arranged in the center, and the electric wires can be arranged on the outer periphery outside the center. This configuration can extend the life of the wires of both the optical cable and the electric wire.

[0065] The air supply pipe 57 that supplies compressed air is made of a flexible material, such as polyurethane. The air supply pipe 57 is characterized by its resistance to damage caused by both bending and twisting. This allows the air supply pipe 57 to be positioned at any desired position in the cross section of the filament bundle.

[0066] In addition to the nylon band described above, a metal cable tie can be used as a member for fixing the wire to the fixing part. When a metal band is used, it is preferable to place a buffer material on the inner peripheral surface of the metal band to prevent the wire from being damaged by contact with the metal band.

[0067] 10 shows an enlarged schematic cross-sectional view of a portion of the second support member of a fifth drive unit according to this embodiment. In the fifth drive unit, the arrangement of the multiple filaments in the cross section of the support member differs from that of the fourth drive unit 5. The fifth drive unit includes a second support member 37 having a fixing portion 37a. The multiple filaments are fixed to the fixing portion 37a with a cable tie 47. The first support member supports the multiple filaments with a structure similar to that of the second support member 37.

[0068] In the fifth drive unit, the optical cable 51 contacts the fixing portion 37a via the buffer material 61. The optical cable 51 contacts the fixing portion 37a at approximately the center in the width direction. In this state, the position of the fixing portion 37a is adjusted so that the optical cable 51 is disposed on the rotation shaft 71. A power cable 56 and an electric wire 58 are disposed around the optical cable 51. In addition, an air supply pipe 57 is disposed around the optical cable 51. In the fifth drive unit, multiple filaments can be bundled together with the optical cable 51 in contact with the center in the width direction of the fixing portion 37a. This allows the optical cable 51 to be easily disposed on the rotation shaft 71 and the filaments to be fixed.

[0069] 11 is an enlarged schematic cross-sectional view of a portion of the second support member of a sixth drive device according to the present embodiment. The sixth drive device includes a second support member 38 having a fixing portion 38a. The first support member supports the umbilical member in a similar configuration to the second support member 38.

[0070] In the sixth drive unit, the optical cable 51 and the air supply pipe 57 are arranged near the rotation axis 71. The power cable 56 and the electric wires 58 are arranged around the optical cable 51 and the air supply pipe 57. The optical cable 51 and the air supply pipe 57 are arranged in the center of the hollow portion 24a. The power cable 56 and the electric wires 58 are arranged on the outer periphery around the center. The first support member and the second support member 38 support the electric wires at a position farther from the rotation axis 71 than the optical cable 51 and the air supply pipe 57.

[0071] As described above, it is preferable that the electric wires be arranged at a position away from the rotation shaft 71. The air supply pipe 57 has a large diameter and can be used as a spacer. By arranging the optical cable 51 and the air supply pipe 57 near the rotation shaft 71 and arranging the electric wires around the optical cable 51 and the air supply pipe 57, the electric wires can be arranged at a position away from the rotation shaft 71.

[0072] Furthermore, in the sixth drive unit, a metal fitting 48 having a U-shaped cross section is used as a member for fixing the umbilical member to the fixing portion 38a. The metal fitting 48 is made of metal. The metal fitting 48 is fixed to the fixing portion 38a with a fastening member such as a bolt 49. Note that a buffer material may be placed on the inner peripheral surface of the metal fitting 48 to prevent damage to the umbilical member.

[0073] In this way, the member for fixing the wires is not limited to a cable tie, and any member such as a metal fitting can be used. A member for bundling multiple wires may be a plastic member with a U-shaped cross section. Alternatively, the wires may be fixed to the fixing portion by adhesive, which serves as a member for bundling multiple wires.

[0074] 10, in the fifth driving device, a dedicated metal fitting may be fixed to the fixing portion for arranging the optical cable 51 on or near the rotation shaft 71. Then, other wires may be arranged around this metal fitting, and the multiple wires may be fixed with a cable tie or the like.

[0075] Although the drive unit of this embodiment is disposed in a joint of a robot, the present invention is not limited to this configuration. The drive unit of this embodiment can be applied to any device that rotates two different members relative to each other around a rotation axis. For example, the device of this embodiment can be applied to a drive unit disposed in a work tool that drives a component of the work tool, or a drive unit of an automatic tool changer of a machine tool.

[0076] The above-described embodiments can be combined as appropriate. In each of the above-described drawings, the same or equivalent parts are designated by the same reference numerals. Note that the above-described embodiments are merely examples and do not limit the invention. Furthermore, the embodiments include modifications of the embodiments as set forth in the claims.

[0077] 1 Robot 2, 3, 4, 5 Drive device 10a to 10f Joint section 12 Upper arm arm 12a Housing 13 Swivel base 13a Housing 21 Electric motor 23 Torque sensor 24 Protective tube 24a Cavity 26 Communication device 29, 31, 33, 35 Support member 30, 32, 34, 36, 37, 38 Support member 29a, 31a, 33a, 35a Fixed section 30a, 32a, 34a, 36a, 37a, 38a Fixed section 50, 51, 52, 53, 54 Optical cable 51a, 51b Optical fiber 51c Sheath 56 Power cable 57 Air supply pipe 58 Electric wire 59 Communication cable 71 Rotation axis

Claims

1. a drive device for rotating a second component of the robot about an axis of rotation relative to the first component of the robot; A member forming a hollow portion extending in a direction along the rotation axis; an optical cable disposed to pass through the inside of the hollow portion; a first support member disposed on one axial side of the cavity and configured to support an optical cable; a second support member disposed on the opposite side of the hollow portion in the axial direction and supporting an optical cable; The first support member is fixed to a member that is stationary when the drive device is driven, the second support member is fixed to a member that rotates when the drive device is driven; the first support member and the second support member are configured to support an optical cable approximately on the axis of rotation; A robot configured such that when a drive device is driven, the second support member rotates relative to the first support member, thereby twisting an optical cable between the first support member and the second support member.

2. The robot according to claim 1 , wherein the member that constitutes the cavity is disposed in a drive device.

3. Equipped with electric wires to supply electricity, The electric wire is arranged to pass through the inside of the hollow portion, The robot according to claim 1 , wherein the first support member and the second support member support the electric wire at a position farther from the rotation shaft than the optical cable.

4. an air supply pipe for supplying pressurized air; The air supply pipe is made of a flexible material, 4. The robot according to claim 3, wherein the first support member and the second support member support the electric wire at a position farther from the rotation axis than the optical cable and the air supply pipe.

5. The drive device includes a driver that controls electricity supplied to the electric motor; the driver includes a communication device for transmitting and receiving information communicated over the optical cable; The robot according to claim 1 or 2, wherein the communication device is disposed inside a housing of the first component member or inside a housing of the second component member.

6. It has a plurality of joints, The member constituting the hollow portion is disposed in the joint portion, A drive unit is provided for each joint, The plurality of drives are configured to perform serial communication; 3. The robot according to claim 1, wherein the optical cable, which is constituted by two optical fibers, is inserted into the hollow portion.

7. The robot according to claim 6 , wherein the optical cable has a structure in which two optical fibers are fixed to each other and integrated.

8. 3. The robot according to claim 1 or 2, wherein the information communicated through the optical cable includes at least one of a position command for an electric motor, a rotational speed command for an electric motor, a current command, a voltage command, information regarding a position or speed detected by a rotational position detector, information regarding a current detected by a current detector, information detected by a sensor, and a signal for controlling a work tool.

9. A drive device that rotates two different members relatively around a rotation axis and has a cavity extending in a direction along the rotation axis, An electric motor that generates a rotational force; a first support member disposed on one side of the hollow portion in the axial direction and supporting an optical cable so as to pass through the hollow portion; a second support member disposed on the opposite side to the one side in the axial direction of the hollow portion and supporting the optical cable; the first support member is fixed to a component of a drive device that is stationary when the electric motor is driven; the second support member is fixed to a component of a drive device that rotates when the electric motor is driven, the first support member and the second support member are configured to support the optical cable approximately on the axis of rotation; A drive device configured such that when the electric motor is driven, the second support member rotates relative to the first support member, thereby twisting the optical cable between the first support member and the second support member.