JP6366665B2 - Robot apparatus, assembly apparatus, gripping hand, and article manufacturing method - Google Patents

Description

  The present invention relates to an assembling apparatus that performs assembling work with two robot arms each provided with an alignment gripping hand.

  Conventionally, many assembling apparatuses that perform assembling work using a robot arm have been used in the industry. In recent years, there has been a demand for an assembly apparatus that realizes assembly work using a robot arm instead of a robot for manual assembly work. On the other hand, in a manual assembly operation in a production factory, a human cell production system is introduced in which a conveyor is removed and a work is directly transported by a person, and a plurality of types of parts and auxiliary materials are assembled to the work.

  There is also a new cell production method called “machine cell”, which combines workers and assembly equipment to increase the productivity of workers.

  From such a background, in order to replace manual assembly work with assembly work using a robot arm, an assembly apparatus capable of assembling a plurality of types of parts and auxiliary materials to a work in one apparatus is required. .

  Patent Document 1 proposes a production apparatus with improved work efficiency capable of assembling a plurality of types of parts and auxiliary materials to a workpiece.

  The production apparatus of Patent Document 1 includes a pair of manipulators having a hand that holds a part of an assembly part, an assembly stage that forms an assembly position of two parts, and a control device that operates the manipulator. The manipulator is arranged so that the work areas of the respective hands partially overlap, and the assembly stage is arranged in the overlapped work area R.

  However, the conventional technique disclosed in Patent Document 1 has the following problems.

  First, many attachment / detachment operations and conveyance operations may occur during assembly.

  The robot arm needs to transport and attach the workpiece from the supply position to the specified position on the assembly stage and attach it to the assembly stage, and to remove and transport the workpiece from the assembly stage to the discharge position. is there. Since the work is held on the assembly stage in this way, the work efficiency is reduced.

  In addition, it is necessary to grip a tooling such as a coating device and a screw tightening driver with a hand, and it is necessary to attach and detach the tooling in accordance with a gripping operation and a releasing operation, which causes a reduction in work efficiency.

  Secondly, there may be a case where a sufficient degree of assembly freedom required for assembly work such as coating operation cannot be secured. Since the work is fixed on the assembly stage, the posture of the work is limited and assembly work with a high degree of freedom cannot be performed. In the case of using an assembly stage, it is often necessary to use a fixing jig in combination with the assembly stage, which causes an increase in production cost.

JP 2010-105106 A

  An object of the present invention is to provide an assembling apparatus having high working efficiency and capable of assembling work with a high degree of freedom.

In order to achieve the above object, a robot apparatus of the present invention has a robot arm and a gripping hand, and the gripping hand includes an attachment attached to the robot arm and a gripping mechanism. A first rotating portion that rotates about one rotating shaft, and a second rotating portion that rotates about a second rotating shaft that is a direction intersecting the first rotating shaft or a direction corresponding to a position of twist. A first part having a first attachment part that is an attachment part to the first rotation shaft, and a second part having a second attachment part. The second rotating part is attached to the second attaching part, the gripping mechanism is attached to the second rotating part, and the second rotating part is provided with the gripping mechanism and the second part. Before and The second rotating part and the gripping mechanism rotate around the first rotating shaft together with the first rotating part, and the gripping mechanism rotates around the second rotating shaft together with the second rotating part. The gripping mechanism or the second rotating part is attached so as to intersect with an imaginary line extending from the first rotating shaft.
The assembly apparatus of the present invention includes a gantry, a first robot arm attached to the gantry, a second robot arm attached to the gantry, a first gripping hand, and a second gripping hand. The first gripping hand includes an attachment attached to the first robot arm and a first gripping mechanism, and the attachment rotates around a first rotation axis. A rotating part, and a second rotating part that rotates about a second rotating axis that is a direction intersecting the first rotating axis or a direction corresponding to a position of twist. The rotating part has a first part having a first attaching part which is an attaching part to the first rotating shaft, and a second part having a second attaching part, and the second rotating part is Attached to the second attachment, Serial first grip mechanism attached to said second rotating part, the second rotating portion located between said second portion and the first gripping mechanism, the said second rotary part first One gripping mechanism rotates about the first rotation axis together with the first rotation part, and the first gripping mechanism rotates about the second rotation axis together with the second rotation part. The first gripping mechanism or the second rotating part is attached so as to intersect a virtual line extending from the first rotating shaft, and the second gripping hand is attached to the second robot arm. And a second gripping mechanism for gripping a part to be assembled to the part gripped by the first gripping hand.
The gripping hand of the present invention is a gripping hand for attaching to a robot arm, and the gripping hand includes an attachment attached to the robot arm and a gripping mechanism, and the attachment has a first rotation axis. A first rotating part that rotates about a center, and a second rotating part that rotates about a second rotating shaft that is a direction intersecting the first rotating shaft or a direction corresponding to a position of torsion, The first rotating part has a first part having a first attaching part that is an attaching part to the first rotating shaft, and a second part having a second attaching part, The second rotating part is attached to the second attaching part, the gripping mechanism is attached to the second rotating part, and the second rotating part is between the gripping mechanism and the second part. The second The rolling part and the gripping mechanism rotate around the first rotation axis together with the first rotation part, and the gripping mechanism rotates around the second rotation axis together with the second rotation part. The gripping mechanism or the second rotating part is attached so as to intersect with an imaginary line obtained by extending the first rotating shaft.
Further, the method for manufacturing an article of the present invention includes a first robot arm, a second robot arm, a first holding hand, and a second holding hand attached to the second robot arm. And the first gripping hand includes an attachment attached to the first robot arm and a gripping mechanism, and the attachment includes a first rotating unit that rotates about a first rotation axis; A second rotating portion that rotates around a second rotating shaft that is a direction intersecting with the first rotating shaft or a direction corresponding to a position of torsion, and the first rotating portion includes: A first part having a first attachment part which is an attachment part to the first rotation shaft; and a second part having a second attachment part, wherein the second rotation part is the second attachment part. Attached to the
The gripping mechanism is attached to the second rotating part, the second rotating part is between the gripping mechanism and the second part, and the second rotating part and the gripping mechanism are The gripping mechanism rotates about the first rotation axis together with the second rotation unit, and the gripping mechanism or the second rotation unit rotates together with the second rotation unit. Is attached so as to intersect with an imaginary line extending from the first rotation axis, and the part gripped by the second gripping hand is driven by the second robot arm, and the first gripping is performed. An article is manufactured by assembling to a part held by a hand.

  According to the assembling apparatus of the present application, the parts are transported to the assembling position with the gripped work without using the assembling stage, and the assembling work is performed by the first and second gripping hands arranged on the robot arm. Can do. For this reason, it is possible to omit the workpiece conveyance / attachment operation and the workpiece removal / conveyance operation caused by using the assembly stage as described above. Furthermore, since the assembly position and posture of the workpiece can be arbitrarily changed, it is possible to secure productivity and perform assembly work with a high degree of freedom.

It is a figure explaining the assembly apparatus which concerns on the 1st Example of this invention. It is a figure explaining the 1st holding hand concerning the 1st example of the present invention. It is a figure explaining the assembly apparatus which concerns on the 2nd Example of this invention. It is a figure explaining the assembly apparatus which concerns on the 3rd Example of this invention. It is a figure explaining the operation example which concerns on 3rd Example of this invention. It is a figure which shows the operation area | region in the 3rd Example of this invention.

[Example 1]
FIG. 1 is a perspective view showing an assembling apparatus of the present invention. In FIG. 1, a gantry 1 is provided with a six-axis multi-joint first robot arm 2 and a second robot arm 3 facing each other. At the tips of the first robot arms 2 and 3, gripping hands 4 and 5 comprising an attachment having a force sensor mounted on the wrist of the robot arm and a centering gripping mechanism arranged in a rotating mechanism are attached. It has been. This force sensor can detect the force applied to the hand during the assembly operation. The force sensor may be attached according to the needs of the user, and is not necessarily essential.

  The figure which shows the 1st holding | grip hand 4 in a present Example is shown in FIG. As shown in FIG. 2, the attachment 26 includes a mechanism that rotates about the rotation axis a. The attachment 26 is further provided with a rotation mechanism 27 having a rotation axis b. The rotation axis b and the rotation axis a of the attachment 26 are attached so as to intersect. The rotating shaft b and the rotating shaft a may be in a twisted position.

  Note that the “twisted position” refers to a positional relationship between two straight lines when the two straight lines in the space are not parallel and do not intersect.

  A first control device 6a and a second control device 6b are connected to the robot arm, respectively, and the robot arm and the gripping hand operate according to a signal issued from the control device. A configuration may be adopted in which a control device is individually arranged for each robot arm.

  Further, when the force sensor is attached to the first or second gripping hand, the assembling work is performed with reference to the magnitude of the force detected by the force sensor.

  The robot arms 2 and 3 are controlled by a control device. The position and orientation of the hand coordinate system provided on the attachment 26 in the three-dimensional space can be changed by a signal transmitted from the control device.

  In this embodiment, the case where the rotation axis a and the rotation axis b are orthogonal to each other will be described below.

  An alignment gripping mechanism 28 is attached to the rotation mechanism 27 so that the alignment position of the alignment gripping mechanism and the rotation axis b of the rotation mechanism coincide.

  The rotation axis b of the rotation mechanism 27 and the rotation axis a of the attachment are arranged so as to intersect with each other, and are attached to the robot arm via the attachment.

  Therefore, the article gripped by the first gripping hand 4 can be transported to an arbitrary position while maintaining the posture, for example, horizontally.

  In general, the posture of the components supplied to the assembling apparatus has a stable posture because the center of gravity of the components is low on the workpiece supply pallet. Therefore, when a part is gripped by the second gripping hand 5, it can be transported to the position of the first gripping hand that is the assembly position without changing the posture of the part, and highly efficient assembly is possible. If the rotation axis a and the rotation axis b are orthogonal to each other, it is convenient because the arrangement of the components of the assembly apparatus and the control program are simplified.

  If the electrical wiring or the like of the alignment gripping mechanism is passed through the hollow shaft of the rotation mechanism 27 via a slip ring, the alignment gripping mechanism 28 can be rotated without limiting the number of rotations of the rotation mechanism 27.

  Referring to the posture of the robot depicted in FIG. 2, the attachment 26 can turn the robot arm along the XZ plane by the rotation axis at the end of the robot arm. Further, the alignment gripping mechanism 28 can turn along the YZ plane by the rotation axis a provided in the attachment 26.

  That is, the change of the rotation angle of the rotation axis a provided in the touchment 26 with respect to the first robot arm 2 and the rotation axis b of the rotation mechanism 27 is not used to change the position and posture of the first robot arm 2. . Therefore, the posture of the alignment gripping mechanism can be controlled independently of the position and posture of the robot arm. According to the signal from the control device, the rotation axis a of the attachment and the rotation axis b of the rotation mechanism rotate in cooperation, whereby the alignment gripping mechanism can be moved in a free posture. Alternatively, the alignment gripping mechanism can be moved by changing the position and orientation of the robot arm while maintaining the orientation of the alignment gripping mechanism. Of course, when only one rotation axis is necessary for maintaining the posture of the alignment gripping mechanism, cooperative rotation is performed in which the change in the rotation angle of the other rotation axis is zero.

  The operation area of the gripping hand provided in each robot arm is arranged as follows. There is a region where the operation region α of the first gripping hand and the operation region β of the second gripping hand overlap, and the first and second gripping hands provided in the two robot arms are in this overlapping region. A collaborative work area in which assembly work is performed in a coordinated manner is provided. In many cases, the hand cannot perform a sufficient assembling operation at the boundary portion that corresponds to the most corner of the operation area of the gripping hand arranged on the robot. Many.

  A detailed description of the operation region will be further described in detail with reference to the drawings in the third embodiment.

  The assembly apparatus of the present invention can reduce the number of joints of the robot arm by adopting the above configuration. As a result, the configuration of the control system can be further simplified, so that the first gripping hand 4 can be operated with high positional accuracy at a low cost. In this way, the number of axes of the robot arm can be reduced. Of course, the technique of the present invention can also be applied to articulated robots having 7 or more axes and robots having fewer than 6 axes.

  The gripping portion of the alignment gripping mechanism 28 is provided with a claw having a shape capable of gripping a plurality of types of annular articles from the outside or the inside depending on the application. The claws perform a flattening operation in the same phase so that a plurality of types of annular articles can be aligned and gripped. In addition, a seating surface for receiving the gripped article is provided at the lower part of the nail, and the shape is such that the tilt of the gripped article can be suppressed or gripped at a predetermined phase.

[Example 2]
FIG. 3 is a diagram showing a second embodiment of the present invention. In FIG. 3, a work unit 30 is installed in the assembly apparatus described in the first embodiment. The work unit performs dedicated assembly work desired by the user, such as screw tightening and various coating materials, and the work unit includes working means 31 for performing assembly work such as a screw tightening driver and a coating device.

  Here, the case where the work unit 30 includes a coating device that discharges the coating material will be described in detail. The working means 31 is hereinafter referred to as a coating device. The coating apparatus contains various coating materials necessary for assembling such as adhesives, grease, and adhesives, and a predetermined amount of coating must be applied to a predetermined position of an assembly part to perform an assembling operation.

  First, the annular component centered and gripped by the first gripping hand 4 described in the first embodiment is set to a predetermined posture at a predetermined position in the vicinity of the coating device in the work unit 30. Transport.

  When coating is performed in the circumferential direction of the annular component, the coating material is started to be discharged from the coating device, and at the same time, is rotated in the direction in which the rotating mechanism 27 is coated at a predetermined amount and at a predetermined speed.

  Thus, in this embodiment, unlike the conventional technique, the coating apparatus is not moved as compared with the technique in which the coating apparatus is gripped by the second gripping hand and the coating apparatus is moved on the assembly stage. Therefore, since it is easy to maintain the gap amount between the coating device and the ring component and the coating angle at the target position accuracy, the coating accuracy can be improved.

  In the prior art, when the annular part is held on the assembly stage, there are cases where the application is not performed physically due to a large number of blind spots with respect to the coating apparatus when applied to the inside of the annular part. In the present invention, since the work unit including the work means for performing the assembly work is installed in the cooperative work area, it is possible to independently change the posture of the annular part with the same degree of freedom as a 6-axis multi-joint robot. it can.

  That is, instead of changing the orientation of the coating device with respect to the component, the orientation of the component with respect to the coating device can be changed.

  Therefore, assembling work with high degree of freedom and high accuracy of application can be performed as compared with the conventional method.

  In addition, by installing the work unit in the cooperative work area of the first and second gripping hands, the parts gripped by the second gripping hand 5 are transported to a predetermined position and posture of the work unit 30, and positioned or positioned. Assembly work may be performed in cooperation with the work means.

  In the above embodiment, the application work has been described as an example. However, in other work, for example, screw tightening work, the working means 31 can be replaced with a screw tightening driver device.

[Example 3]
FIG. 4 is a diagram showing a third embodiment of the present invention. In FIG. 4, a workpiece supply pallet 42 is installed on a workpiece supply base 41 in the operation area of the first gripping hand, and a plurality of annular workpieces 43 having an annular shape are placed on the pallet. . In addition, a component supply component supply pallet 52 is installed on the component supply stand 51 in the operation area of the second gripping hand, and a plurality of child pallets are arranged on the component supply pallet 52. On each child pallet, a plurality of one-shaped annular parts 53 are stacked.

  FIG. 6 is a diagram showing an operation area of the gripping hand provided in each robot arm in the third embodiment of the present invention. A cooperative work area 60 in which two robot arms cooperate to perform assembly work is provided in an overlapping area of the first grip hand movement area α and the second grip hand movement area β.

  Hereinafter, the operation in the third embodiment of the present invention will be described in detail.

  As shown in FIG. 5A, the first gripping hand 4 aligns and grips the annular workpiece 43 on the workpiece supply pallet 42 from above. Thereafter, the workpiece is conveyed to the cooperative work area 60 while changing the posture of the workpiece. On the other hand, the second gripping hand 5 grips the component 53 of the component supply component supply pallet 52 of the component supply stand 51 while aligning the component 53 from above and transports it to the cooperative work area 60. FIG. 4 shows the state of the robot arm immediately before assembly. After that, assembly work is performed with two robot arms.

  Then, the second gripping hand 5 moves to the component supply base 51, grips the component 53 and conveys it to the cooperative work area 60, and then performs assembly work for assembling the component to the annular workpiece 43. Various components are stored in the component supply pallet, and a plurality of types of components are sequentially conveyed by the second gripping hand 5 and an assembly operation is performed.

  The workpiece supply base 41 is outside the operation area of the second gripping hand 5, and the component supply base 51 is outside the operation area of the first gripping hand. Therefore, there is no risk of interference between movable bodies such as the gripping hand and the robot arm outside the overlapping region of the region α and the region β. Therefore, it is possible to simplify preparations for starting production activities such as layout ingenuity to avoid interference, program changes, robot teaching, etc., and shorten the start-up time of production activities by assembly equipment it can.

  The annular work is moved in a predetermined position and posture (for example, the assembly part is directed upward in the Z direction so as to be suitable for assembly) and the cooperative work area 60 is moved from the component supply base 51 by the second gripping hand 5. When moving the component 53 to the position, it is almost unnecessary to change the posture of the component 53. Therefore, efficient parts conveyance becomes possible.

  Further, the assembling apparatus is further provided with a camera, and during the transfer operation from the component supply stand 51 to the cooperative work area 60, the position and phase of the parts are detected by image capturing and detected by the camera, and are being transferred to the cooperative work area 60. Alternatively, the assembly work may be performed by correcting the parts to a predetermined position and phase. By performing the assembly work based on the imaging information as described above, it is possible to perform a further complicated work such as a fitting assembly.

  Further, as shown in FIG. 5B, during the operation in which the second gripping hand 5 grips and transports the next part, the first gripping hand transports to a predetermined position of the work unit 30 and cooperates with the working means 31. Thus, assembly work can be performed.

  Of course, depending on the setup of the assembly work, the second gripping hand can grip the part arranged in the second gripping hand operation region β and execute the above-described operation.

  As described above, since the annular work 43 is continuously assembled, efficient assembly work can be performed.

  In addition, since these configurations have no risk of interference with the gripping hand and the robot arm other than the cooperative work area 60 shown in FIG. 6, two robot arms are controlled by one control device like a double-arm robot. It is not always necessary to control. Therefore, if the interlock in the cooperative work area 60 is applied, a combination of one control device and one robot arm can be made. In that case, a program etc. can be simplified compared with a general two-arm robot.

  In addition, the workpiece supply pallet 42 and the component supply component supply pallet 52 may be appropriately configured as an unmanned automatic assembly apparatus by automatically supplying and automatically discharging the workpiece supply pallet 42 and the component supply pallet 52 with an automatic guided vehicle such as AGV.

DESCRIPTION OF SYMBOLS 1 Stand 2 1st robot arm 3 2nd robot arm 4 1st holding hand 5 2nd holding hand 2 6 Attachment 2 7 Rotating mechanism 2 8 Centering holding mechanism a Rotating shaft of attachment b Rotating shaft of rotating mechanism

Claims (19)

A robot arm and a gripping hand;
The gripping hand includes an attachment attached to the robot arm and a gripping mechanism,
The attachment is centered on a first rotating portion that rotates about a first rotating shaft and a second rotating shaft that is a direction intersecting the first rotating shaft or a direction corresponding to a twisted position. A second rotating part that rotates as
The first rotating part has a first part having a first attaching part that is an attaching part to the first rotating shaft, and a second part having a second attaching part,
The second rotating part is attached to the second attaching part,
The gripping mechanism is attached to the second rotating part,
The second rotating part is between the gripping mechanism and the second part;
The second rotating part and the gripping mechanism rotate around the first rotating shaft together with the first rotating part,
The gripping mechanism rotates around the second rotating shaft together with the second rotating portion, and the gripping mechanism or the second rotating portion intersects an imaginary line extending the first rotating shaft. The robot apparatus characterized by being attached in the manner described above.   The robot apparatus according to claim 1, wherein the robot arm is a six-axis articulated robot arm.   The robot apparatus according to claim 1, wherein the gripping mechanism has an alignment mechanism, and an alignment position of the alignment mechanism and the second rotation axis coincide with each other.   The robot apparatus according to claim 1, wherein a plurality of claws are attached to the gripping mechanism, and the plurality of claws are opened and closed in the same phase.   5. The robot apparatus according to claim 1, wherein the first rotation axis and the second rotation axis are orthogonal to each other. A gantry and a first robot arm attached to the gantry;
A second robot arm attached to the mount;
A first gripping hand;
A second gripping hand,
The first gripping hand includes an attachment attached to the first robot arm and a first gripping mechanism,
The attachment is centered on a first rotating portion that rotates about a first rotating shaft and a second rotating shaft that is a direction intersecting the first rotating shaft or a direction corresponding to a twisted position. A second rotating part that rotates as
The first rotating part has a first part having a first attaching part that is an attaching part to the first rotating shaft, and a second part having a second attaching part,
The second rotating part is attached to the second attaching part,
The first gripping mechanism is attached to the second rotating part,
The second rotating part is between the first gripping mechanism and the second part;
The second rotating part and the first gripping mechanism rotate around the first rotating shaft together with the first rotating part,
The first gripping mechanism rotates around the second rotating shaft together with the second rotating portion, and the first gripping mechanism or the second rotating portion extends the first rotating shaft. Attached to intersect the virtual line
The second gripping hand is attached to the second robot arm and has a second gripping mechanism for gripping a part to be assembled to a part gripped by the first gripping hand. An assembling device characterized. The assembly apparatus according to claim 6, wherein the first robot arm and the second robot arm are 6-axis articulated robot arms. The assembly apparatus according to claim 6 or 7, wherein the first gripping mechanism has an alignment mechanism, and an alignment position of the alignment mechanism and the second rotation axis coincide with each other. 9. The assembly apparatus according to claim 6, wherein a plurality of claws are attached to the first gripping mechanism, and the plurality of claws open and close in the same phase.   The assembly apparatus according to any one of claims 6 to 9, wherein the first rotation axis and the second rotation axis are orthogonal to each other. A gripping hand for attaching to a robot arm,
The gripping hand includes an attachment attached to the robot arm and a gripping mechanism,
The attachment is centered on a first rotating portion that rotates about a first rotating shaft and a second rotating shaft that is a direction intersecting the first rotating shaft or a direction corresponding to a twisted position. A second rotating part that rotates as
The first rotating part has a first part having a first attaching part that is an attaching part to the first rotating shaft, and a second part having a second attaching part,
The second rotating part is attached to the second attaching part,
The gripping mechanism is attached to the second rotating part,
The second rotating part is between the gripping mechanism and the second part;
The second rotating part and the gripping mechanism rotate around the first rotating shaft together with the first rotating part,
The gripping mechanism rotates around the second rotating shaft together with the second rotating portion, and the gripping mechanism or the second rotating portion intersects an imaginary line extending the first rotating shaft. A gripping hand that is attached in the manner described above.   The gripping hand according to claim 11, wherein the gripping mechanism has a centering mechanism, and a centering position of the centering mechanism and the second rotation axis coincide with each other.   The gripping hand according to claim 11 or 12, wherein a plurality of claws are attached to the gripping mechanism, and the plurality of claws are opened and closed in the same phase.   The gripping hand according to claim 11, wherein the first rotating shaft and the second rotating shaft are orthogonal to each other. The first robot arm,
A second robot arm,
A first gripping hand;
A second gripping hand attached to the second robot arm,
The first gripping hand includes an attachment attached to the first robot arm and a gripping mechanism,
The attachment is centered on a first rotating portion that rotates about a first rotating shaft and a second rotating shaft that is a direction intersecting the first rotating shaft or a direction corresponding to a twisted position. A second rotating part that rotates as
The first rotating part has a first part having a first attaching part that is an attaching part to the first rotating shaft, and a second part having a second attaching part,
The second rotating part is attached to the second attaching part,
The gripping mechanism is attached to the second rotating part,
The second rotating part is between the gripping mechanism and the second part;
The second rotating part and the gripping mechanism rotate around the first rotating shaft together with the first rotating part,
The gripping mechanism rotates around the second rotating shaft together with the second rotating portion, and the gripping mechanism or the second rotating portion intersects an imaginary line extending the first rotating shaft. The parts that are attached in this manner and are gripped by the second gripping hand are driven to drive the second robot arm and are assembled to the parts gripped by the first gripping hand. A method for producing an article characterized by 16. The article manufacturing method according to claim 15, wherein the first robot arm and the second robot arm are 6-axis articulated robot arms.   The method of manufacturing an article according to claim 15 or 16, wherein the gripping mechanism has an alignment mechanism, and an alignment position of the alignment mechanism and the second rotation axis coincide with each other.   The method for manufacturing an article according to any one of claims 15 to 17, wherein a plurality of claws are attached to the gripping mechanism, and the plurality of claws are opened and closed in the same phase.   The method for manufacturing an article according to any one of claims 15 to 18, wherein the first rotating shaft and the second rotating shaft are orthogonal to each other.

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