Patent Publication Number: US-2022234220-A1

Title: Robot, Attachment Method, And Detachment Method

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-009739, filed Jan. 25, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a robot, an attachment method, and a detachment method. 
     2. Related Art 
     JP-A-2019-111598 discloses a robot having a first joint member, a second joint member pivotable around an axial line relative to the first joint member, a reducer coupling the first joint member and the second joint member, and a motor coupled to the reducer. In the robot of JP-A-2019-111598, in order to prevent separation of the first joint member and the second joint member when the reducer is detached, the first joint member and the second joint member are coupled in another part than the reducer. 
     However, in the robot of JP-A-2019-111598, it is necessary to first detach the motor, and then, detach the reducer. Accordingly, there are many steps for detaching the reducer, and work therefor may become complex. 
     SUMMARY 
     A robot according to an aspect of the present disclosure includes a first member having a first mounting surface, a second member having an opening located at the first mounting surface side with respect to the first member and facing the first member, and a second mounting surface located at an opposite side to the first member, and a joint actuator coupling the first member and the second member and relatively pivoting the first member and the second member, the joint actuator has a flange fixed to the second mounting surface, a motor placed at an opposite side to the first member with respect to the flange, and a reducer placed at the first member side with respect to the flange, projecting from the opening to the first member side, and fixed to the first mounting surface, a width of the opening is smaller than a width of the flange, a width of the motor is smaller than the width of the flange, and a width of the reducer is smaller than the width of the opening, wherein the joint actuator is mounted on the second mounting surface from the opposite side to the first member and the reducer is projected from the opening to the first member side, the flange is fastened to the second member from the opposite side to the first member using a first screw, the reducer is fastened to the first member from an opposite side to the second member using a second screw, and the first member and the second member are coupled. 
     An attachment method according to an aspect of the present disclosure is an attachment method for a joint actuator coupling a first member having a first mounting surface and a second member having an opening located at the first mounting surface side with respect to the first member and facing the first member, and a second mounting surface located at an opposite side to the first member, and relatively pivoting the first member and the second member, the joint actuator has a flange fixed to the second mounting surface, a motor placed at an opposite side to the first member with respect to the flange, and a reducer placed at the first member side with respect to the flange, projecting from the opening to the first member side, and fixed to the first mounting surface, a width of the opening is smaller than a width of the flange, a width of the motor is smaller than the width of the flange, and a width of the reducer is smaller than the width of the opening. The method includes mounting the joint actuator on the second mounting surface from the opposite side to the first member and projecting the reducer from the opening to the first member side, fastening the flange to the second member from the opposite side to the first member using a first screw, and fastening the reducer to the first member from an opposite side to the second member using a second screw. 
     A detachment method according to an aspect of the present disclosure is a detachment method for a joint actuator coupling a first member having a first mounting surface and a second member having an opening located at the first mounting surface side with respect to the first member and facing the first member, and a second mounting surface located at an opposite side to the first member, and relatively pivoting the first member and the second member, the joint actuator has a flange fixed to the second mounting surface, a motor placed at an opposite side to the first member with respect to the flange, and a reducer placed at the first member side with respect to the flange, projecting from the opening to the first member side, and fixed to the first mounting surface, a width of the opening is smaller than a width of the flange, a width of the motor is smaller than the width of the flange, a width of the reducer is smaller than the width of the opening, the flange is fixed to the second member from the opposite side to the first member by a first screw, and the reducer is fixed to the first member from an opposite side to the second member by a second screw. The method includes removing the second screw, removing the first screw, and pulling out the joint actuator to the opposite side to the first member. 
     A fixing member according to an aspect of the present disclosure is a fixing member fixing a first member and a second member when a joint actuator is detached from a robot or when the joint actuator is attached to the robot having the first member, the second member, and the joint actuator coupling the first member and the second member and relatively pivoting the first member and the second member, and the member includes a first insertion hole through which a screw used for fixation to the first member is inserted, and a second insertion hole through which a screw used for fixation to the second member is inserted. 
     A maintenance system according to an aspect of the present disclosure fixes a first member and a second member by a fixing member when a joint actuator is detached from a robot or when the joint actuator is attached to the robot having the first member, the second member, and the joint actuator coupling the first member and the second member and relatively pivoting the first member and the second member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view showing a robot according to a preferred embodiment of the present disclosure. 
         FIG. 2  is a sectional view showing a joint actuator coupling a first arm and a second arm. 
         FIG. 3  is a sectional view for explanation of a detachment method for the joint actuator shown in  FIG. 2 . 
         FIG. 4  is a sectional view for explanation of the detachment method for the joint actuator shown in  FIG. 2 . 
         FIG. 5  is a sectional view for explanation of the detachment method for the joint actuator shown in  FIG. 2 . 
         FIG. 6  is a sectional view for explanation of the detachment method for the joint actuator shown in  FIG. 2 . 
         FIG. 7  is a sectional view for explanation of the detachment method for the joint actuator shown in  FIG. 2 . 
         FIG. 8  is a sectional view for explanation of an attachment method for the joint actuator shown in  FIG. 2 . 
         FIG. 9  is a sectional view for explanation of the attachment method for the joint actuator shown in  FIG. 2 . 
         FIG. 10  is a sectional view for explanation of the attachment method for the joint actuator shown in  FIG. 2 . 
         FIG. 11  is a sectional view showing a modified example of a fixing member fixing the first arm and the second arm. 
         FIG. 12  is a sectional view showing a modified example of the fixing member fixing the first arm and the second arm. 
         FIG. 13  is a sectional view showing a modified example of the fixing member fixing the first arm and the second arm. 
         FIG. 14  is a sectional view showing a joint actuator coupling a base and the first arm. 
         FIG. 15  is a sectional view showing a fixing member fixing the base and the first arm. 
         FIG. 16  is a sectional view showing a modified example of the fixing member fixing the base and the first arm. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     As below, a robot, an attachment method, a detachment method, a fixing member, and a maintenance system according to the present disclosure will be explained in detail based on embodiments shown in the accompanying drawings. 
       FIG. 1  is a side view showing a robot according to a preferred embodiment of the present disclosure.  FIG. 2  is a sectional view showing a joint actuator coupling a first arm and a second arm.  FIGS. 3 to 7  are sectional views for explanation of a detachment method for the joint actuator shown in  FIG. 2 .  FIGS. 8 to 10  are sectional views for explanation of an attachment method for the joint actuator shown in  FIG. 2 .  FIGS. 11 to 13  are sectional views showing modified examples of a fixing member fixing the first arm and the second arm.  FIG. 14  is a sectional view showing a joint actuator coupling a base and the first arm.  FIG. 15  is a sectional view showing a fixing member fixing the base and the first arm.  FIG. 16  is a sectional view showing a modified example of the fixing member fixing the base and the first arm. 
     For convenience of explanation, in the respective drawings, an X-axis, a Y-axis, and a Z-axis as three axes orthogonal to one another are shown. Further, in the following description, the upsides, i.e., the arrow-head sides of the Z axes in the drawings are “upward” in the vertical direction, and the downsides, i.e., the opposite sides to the arrow-heads of the Z axes in the drawings are referred to as “downward” in the vertical direction. 
     A robot  1  shown in  FIG. 1  is a scalar robot and used in individual work of e.g. holding, transport, assembly, inspection, etc. of workpieces such as electronic components. Note that the application of the robot  1  is not particularly limited. 
     The robot  1  has a base  2  fixed to a floor surface and an arm  3  coupled to the base  2 . Further, the arm  3  has a first arm  31  having a proximal end portion coupled to the base  2  and pivoting around a first pivot axis J 1  along the vertical direction relative to the base  2 , and a second arm  32  having a proximal end portion coupled to a distal end portion of the first arm  31  and pivoting around a second pivot axis J 2  along the vertical direction relative to the first arm  31 . The first pivot axis J 1  and the second pivot axis J 2  are parallel. 
     A working head  33  is provided in the distal end portion of the second arm  32 . The working head  33  has a spline nut  331  and a ball screw nut  332  coaxially placed in the distal end portion of the second arm  32 , and a spline shaft  333  inserted through the spline nut  331  and the ball screw nut  332 . The spline shaft  333  is rotatable around a third pivot axis J 3  as a center axis thereof along the vertical direction relative to the second arm  32  and movable upward and downward along the third pivot axis J 3 . The third pivot axis J 3  is parallel to the first pivot axis J 1  and the second pivot axis J 2 . 
     An end effector  34  is attached to the lower end portion of the spline shaft  333 . The end effector  34  is detachable and one suitable for intended work is appropriately selected. The end effector  34  includes e.g. a hand holding a workpiece by nipping or suction and a work tool for performing predetermined processing on a workpiece. 
     The robot  1  has a joint actuator  51  coupling the base  2  and the first arm  31  and pivoting the first arm  31  around the first pivot axis J 1  relative to the base  2 , and a joint actuator  52  coupling the first arm  31  and the second arm  32  and pivoting the second arm  32  around the second pivot axis J 2  relative to the first arm  31 . Further, the robot  1  has a driver  53  rotating the spline nut  331  and rotating the spline shaft  333  around the third pivot axis J 3 , and a driver  54  rotating the ball screw nut  332  and moving the spline shaft  333  upward and downward in directions along the third pivot axis J 3 . 
     The robot  1  has a cover member  39  detachably attached to the second arm  32  and covering and protecting the individual units placed in the second arm  32 , particularly, the joint actuator  52  and the drivers  53 ,  54 . 
     The robot  1  has a robot control apparatus  10  placed within the base  2  and controlling driving of the joint actuators  51 ,  52  and the drivers  53 ,  54  according to a command from a host computer (not shown). The robot control apparatus  10  independently controls the joint actuators  51 ,  52  and the drivers  53 ,  54 , and thereby, may control the robot  1  to perform desired work. The robot control apparatus  10  has e.g. a processor including a computer and processing information, a memory communicably connected to the processor, and an external interface. Various programs that can be executed by the processor are stored in the memory, and the processor may read and execute various programs etc. stored in the memory. 
     As above, the overall configuration of the robot  1  is briefly explained. Next, the joint actuators  51 ,  52  will be described in detail. Note that the joint actuators  51 ,  52  are placed in different positions, but have the same configuration as each other. As below, the joint actuator  52  will be explained in detail and the joint actuator  51  will be briefly explained mainly regarding only the difference from the joint actuator  52 . 
     As shown in  FIG. 2 , the joint actuator  52  has a flange  9  fixed to a second mounting surface  321  of the second arm  32 , a motor  6  as a drive source placed to project upward from the flange  9 , an encoder  8  as a rotation detector placed on the upside of the motor  6 , and a wave gearing  7  as a reducer projecting downward from the flange  9  and fixed to a first mounting surface  311  of the first arm  31 . Note that the first mounting surface  311  and the second mounting surface  321  each face upward. 
     A width W 6  of the motor  6  and a width W 7  of the wave gearing  7  are each smaller than a width W 9  of the flange  9 . That is, W 6 &lt;W 9  and W 7 &lt;W 9 . A width W 8  of the encoder  8  is smaller than the width W 6  of the motor  6 . That is, W 8 &lt;W 6 . Accordingly, as seen from the upside in the vertical direction, the flange  9  is visually recognized to project from around the encoder  8  and the motor  6  and, as seen from the downside in the vertical direction, the flange  9  is visually recognized to project from around the wave gearing  7 . Note that, in the embodiment, the flange  9 , the motor  6 , and the wave gearing  7  each have a circular shape in the plan view from the vertical direction, and the “width” is synonymous with “diameter”. 
     The motor  6  is an AC servo motor. The motor  6  is not particularly limited, but e.g. a DC servo motor, a stepping motor, or the like may be used. 
     The motor  6  has a rotor  61 , a stator  62 , and a housing  63  housing the rotor and the stator. 
     The rotor  61  has a shaft  611  as a rotation axis and a magnet  612 . The shaft  611  is supported by the housing  63  rotatably around a center axis A thereof via a pair of bearings  651 ,  652 . The center axis A coincides with the second pivot axis J 2 . Further, the shaft  611  is coupled to the wave gearing  7  in the lower end portion of the shaft and coupled to the encoder  8  in the upper end portion of the shaft. Thereby, the rotation of the shaft  611  is transmitted to the wave gearing  7  and the encoder  8 . 
     The stator  62  is placed to surround the rotor  61  around the center axis A. The stator  62  has cores  621  placed at predetermined intervals in the circumferential direction and coils  622  wound around the respective cores  621 . When an alternating current flows in the stator  62 , the stator  62  serves as an electromagnet and the N-pole and the S-pole are alternatively switched. Accordingly, the magnet  612  of the rotor  61  is attracted and repulsed, and thereby, the shaft  611  rotates around the center axis A. 
     The flange  9  is integrally formed with the housing  63  and has a disc shape projecting outward in the radial direction of the center axis A from the housing  63 . Note that the flange  9  may be separately formed from the housing  63 . The flange  9  has a plurality of insertion holes  91  placed at equal intervals along the circumferential direction. Further, the flange  9  is fixed to the second arm  32  by first screws B 1  inserted through the insertion holes  91 . Thereby, the motor  6  is fixed to the second arm  32  via the flange  9 . Specifically, an opening  322  penetrating in the vertical directions of the second arm  32  is formed in a position facing the distal end portion of the first arm  31  in the proximal end portion of the second arm  32 . A width W 3  of the opening  322  is smaller than the width W 9  of the flange  9  and larger than the width W 7  of the wave gearing  7 . That is, W 7 &lt;W 3 &lt;W 9 . The joint actuator  52  is mounted on the second mounting surface  321  of the second arm  32  to block the opening  322  from the upside, and the flange  9  is fastened to the second arm  32  by the first screws B 1  inserted through the insertion holes  91  from the upside. 
     The wave gearing  7  is placed adjoiningly to the motor  6  along the center axis A on the downside, i.e., the first arm  31  side of the motor  6 . The wave gearing  7  reduces and outputs the rotation of the shaft  611  at a higher reduction ratio and generates higher torque in proportion to the reduction ratio. The wave gearing  7  has a wave generator  71 , a flexspline  73 , and a circular spline  76 . As will be described later, in the wave gearing  7 , the wave generator  71  is at an input side to which power of the motor  6  is input and the circular spline  76  is at an output side from which the power of the motor  6  is reduced and output. 
     The circular spline  76  is an annular internal gear formed by a rigid body that is substantially inflexible. The circular spline  76  has a coupling portion  761  fixed to the first arm  31  and a fixed portion  762  fixed to the flange  9 . The coupling portion  761  and the fixed portion  762  are coupled by a bearing  763  and the coupling portion  761  is rotatable relative to the fixed portion  762 . 
     Internal teeth  761   a  meshing with the flexspline  73  are formed in the inner circumferential part of the coupling portion  761 . The coupling portion  761  has fixing screw holes  761   b  opening to a lower surface  761   c  for fixing the coupling portion  761  to the first arm  31 . The coupling portion  761  is fixed to the first arm  31  by second screws B 2  screwed into the fixing screw holes  761   b . Specifically, when the flange  9  is fastened to the second arm  32  by the screws, the wave gearing  7  projects downward from the second arm  32  via the opening  322  and the lower surface  761   c  of the coupling portion  761  contacts the first mounting surface  311  of the first arm  31 . In the first arm  31 , insertion holes  312  for insertion of the second screws B 2  are formed in positions corresponding to the fixing screw holes  761   b . The second screws B 2  inserted through the insertion holes  312  from the downside of the first arm  31  are screwed into the fixing screw holes  761   b , and the coupling portion  761  is fastened to the first arm  31  by the screws. Thereby, the coupling portion  761  as the output portion of the wave gearing  7  is fixed to the first arm  31 . 
     On the other hand, the fixed portion  762  has insertion holes  762   a  for fixing the fixed portion  762  to the flange  9 , and fixed to the flange  9  by third screws B 3  inserted through the insertion holes  762   a.    
     The flexspline  73  is placed inside of the circular spline  76 . The flexspline  73  has a tubular portion  731  having flexibility to be flexurally deformable along the outer circumference of the wave generator  71 , and a flange portion  732  extending outward in the radial direction of the center axis A from the lower end part of the tubular portion  731 . 
     External teeth  731   a  meshing with the internal teeth  761   a  of the circular spline  76  are formed in the outer circumferential part of the tubular portion  731 . The number of teeth of the external teeth  731   a  is set to be smaller than the number of teeth of the internal teeth  761   a . The flange portion  732  is provided between the circular spline  76  and the flange  9 . The flange portion  732  has insertion holes  732   a  for fixing the flange portion  732  to the flange  9 , and is fixed to the flange  9  with the fixed portion  762  by the third screws B 3  inserted through the insertion holes  732   a.    
     The wave generator  71  has a wave generation portion  711  rotating with the rotation of the shaft  611  with the shaft  611  inserted in the wave generation portion, and a bearing  712  fitted between the wave generation portion  711  and the flexspline  73 . The wave generation portion  711  has an outer circumference in an elliptical shape or an oval shape in the plan view from the center axis A direction. The wave generator  71  contacts the inner circumferential surface of the tubular portion  731  of the flexspline  73 , flexes the tubular portion  731  into an elliptical shape or an oval shape, and partially meshes the external teeth  731   a  of the tubular portion  731  with the internal teeth  761   a  of the circular spline  76 . Thereby, the circular spline  76  meshes with the teeth in the long axis part and completely separates from the teeth in the short axis part. 
     When drive power from the motor  6  is input to the wave generator  71 , the flexspline  73  and the circular spline  76  relatively rotate around the center axis A due to the difference in number of teeth while the mesh position with each other sequentially moves in the circumferential direction. In the embodiment, the flange portion  732  of the flexspline  73  and the fixed portion  762  of the circular spline  76  are fixed to the second arm  32  via the flange  9  and the coupling portion  761  of the circular spline  76  is fixed to the first arm  31 , and thereby, the second arm  32  pivots around the second pivot axis J 2  relative to the first arm  31 . According to the wave gearing  7 , the rotation input from the motor  6  to the wave generator  71  is reduced and output from the coupling portion  761  of the circular spline  76 , and torque proportional to the reduction ratio may be obtained at the output side. 
     The encoder  8  is placed adjoiningly to the motor  6  along the center axis A and located on the upside of the motor  6 . The encoder  8  has an optical scale  81  fixed to the shaft  611  and an optical sensor  82  detecting the rotation state of the optical scale  81 . The optical scale  81  rotates around the center axis A with the shaft  611 . On the upper surface of the optical scale  81 , a detection pattern (not shown) by which the rotation angle of the optical scale  81  may be obtained is formed. On the other hand, the optical sensor  82  has a light emitting device that outputs light toward the detection pattern on the optical scale  81  and a light receiving device that receives the light reflected by the detection pattern. In the encoder  8  having the above described configuration, the waveform of the output signal from the light receiving device changes with the rotation of the optical scale  81  around the center axis A. Accordingly, the rotation angle of the optical scale  81  may be detected based on the output signal. 
     As above, the configuration of the joint actuator  52  is explained. Next, a method of detaching the joint actuator  52  from the robot  1  for replacement and maintenance will be explained. First, as shown in  FIG. 3 , the cover member  39  is detached from the second arm  32  and the joint actuator  52  is exposed. Then, as shown in  FIG. 4 , a fixing member  100  is fixed to the first arm  31  and the second arm  32  to couple the first arm  31  and the second arm  32 , and thereby, the relative position of these arms is fixed. Note that the fixing member  100  will be described later in detail. 
     Then, as shown in  FIG. 5 , the second screws B 2  fixing the coupling portion  761  to the first arm  31  are approached from the downside of the first arm  31  and the second screws B 2  are detached. Thereby, the joint actuator  52  is separated from the first arm  31 . Note that no member impossible or difficult to be detached is placed at the downside of the second screws B 2  and work paths L 1  for approaching the second screws B 2  from the downside are secured in the first arm  31 . In other words, when the first arm  31  is seen from the downside, the second screws B 2  are seen. Thereby, the second screws B 2  may be smoothly detached. 
     Then, as shown in  FIG. 6 , the first screws B 1  fixing the flange  9  to the second arm  32  are approached from the upside of the second arm  32  and the first screws B 1  are detached. Thereby, the joint actuator  52  is separated from the second arm  32 . Note that no member impossible or difficult to be detached is placed at the upside of the first screws B 1  and work paths L 2  for approaching the first screws B 1  from the upside are secured in the second arm  32 . In other words, when the second arm  32  is seen from the upside, the first screws B 1  are seen. Thereby, the first screws B 1  may be smoothly detached. 
     Then, as shown in  FIG. 7 , the joint actuator  52  is pulled out upward and detached from the robot  1 . Thereby, the detachment of the joint actuator  52  is completed. According to the above described steps, the joint actuator  52  may be easily detached from the robot  1 . Particularly, unlike the related art, the motor  6  and the wave gearing  7  may be integrally detached at the same time, and extremely high work efficiency may be exerted. Note that the steps for detachment work are not limited to those. For example, in the above description, the second screws B 2  are detached before the first screws B 1 , however, the first screws B 1  may be detached before the second screws B 2 . Or, the first screws B 1  and the second screws B 2  may be detached at the same time or alternately detached. 
     The first arm  31  and the second arm  32  are fixed by the fixing member  100 , and thereby, detachment work of the joint actuator  52  may be smoothly performed. Further, even when the joint actuator  52  is detached from the robot  1 , the relative position of the first arm  31  and the second arm  32  may be maintained. 
     Next, a method of attaching the joint actuator  52  will be explained after  FIG. 7 . Note that the attachment method for the joint actuator  52  has a reverse procedure to the above described detachment method and will be briefly explained. First, as shown in  FIG. 8 , the joint actuator  52  is entered from the upside of the second arm  32  and mounted on the second mounting surface  321  to block the opening  322 . Thereby, the wave gearing  7  projects downward via the opening  322  and the lower surface  761   c  of the coupling portion  761  contacts the first mounting surface  311  of the first arm  31 . 
     Then, as shown in  FIG. 9 , the flange  9  is approached from the upside and the flange  9  is fixed to the second arm  32  using the first screws B 1 . The work paths L 2  are secured, and the first screws B 1  may be smoothly attached. Then, as shown in  FIG. 10 , the lower surface  761   c  of the coupling portion  761  is approached from the downside of the first arm  31 , and the coupling portion  761  is fixed to the first arm  31  using the second screws B 2 . The work paths L 1  are secured, and the second screws B 2  may be smoothly attached. Then, the fixing member  100  is detached from the robot  1 , and the cover member  39  is attached to the second arm  32 . Thereby, the attachment of the joint actuator  52  is completed. 
     According to the above described steps, the joint actuator  52  may be easily attached to the robot  1 . Particularly, unlike the related art, the motor  6  and the wave gearing  7  may be integrally attached at the same time, and extremely high work efficiency may be exerted. The first arm  31  and the second arm  32  are fixed by the fixing member  100 , and thereby, attachment work of the joint actuator  52  may be smoothly performed. Particularly, the relative position of the first arm  31  and the second arm  32  does not shift when the joint actuator  52  is attached and detached, and calibration of the encoder  8  after attachment of the joint actuator  52  is unnecessary. Therefore, efforts for replacement or maintenance may be reduced and operation of the robot  1  may be restarted earlier after attachment of the joint actuator  52 . 
     Next, the fixing member  100  will be explained. As shown in  FIG. 4 , the fixing member  100  of the embodiment has a U-shape and includes a bottom portion  110  and a pair of wall portions  120 ,  130  stood from ends of the bottom portion  110 . The fixing member  100  is attached from the downside, and the bottom portion  110  is fixed to the first arm  31  and the wall portions  120 ,  130  are fixed to the second arm  32 . Thereby, the first arm  31  and the second arm  32  are fixed via the fixing member  100 . 
     The bottom portion  110  has a first insertion hole  111 . The bottom portion  110  is fastened to the first arm  31  by screwing of a fourth screw B 4  inserted through the first insertion hole  111  from the downside into a fixing screw hole  319  formed in a position corresponding to the first insertion hole  111  of the first arm  31 . On the other hand, the wall portions  120 ,  130  have second insertion holes  121 ,  131 , respectively. The wall portions  120 ,  130  are fastened to the second arm  32  by screwing of fifth screws B 5  inserted from sides through the second insertion holes  121 ,  131  into fixing screw holes  329  formed in positions corresponding to the second insertion holes  121 ,  131  of the second arm  32 . Thereby, the first arm  31  and the second arm  32  are fixed via the fixing member  100  and, even when the joint actuator  52  is detached from the robot  1 , the relative position of the first arm  31  and the second arm  32  may be maintained. 
     The fixing member  100  has a shape not overlapping with the work paths L 1  or the work paths L 2 . In other words, with the fixing member  100  attached to the robot  1 , when the first arm  31  is seen from the downside, the second screws B 2  are seen and, when the second arm  32  is seen from the upside, the first screws B 1  are seen. Thereby, the work paths L 1  and the work paths L 2  are not blocked by the fixing member  100  and attachment and detachment of the first screws B 1  and the second screws B 2  are not hindered. In the embodiment, through holes  112  are formed in the parts overlapping with the work paths L 1  to form the shape not overlapping with the work paths L 1 . Note that the through holes  112  of the embodiment are closed holes, however, may be formed as cutouts coupled to the outer edge of the bottom portion  110 . 
     As above, the fixing member  100  is explained, however, the fixing member  100  is not particularly limited as long as the member may fix the first arm  31  and the second arm  32 . For example, as shown in  FIG. 11 , the fixing member  100  may further have grooves as positioning portions  128 ,  138  formed to extend in the vertical directions in the inner surfaces of the wall portions  120 ,  130 , respectively, and may be positioned with respect to the robot  1  by engagement of the grooves with projections  328  formed on the side surface of the second arm  32 . Thereby, the attachment of the fixing member  100  to the robot  1  is easier. Or, for example, as shown in  FIG. 12 , the fixing member  100  may have an L-shape and may be fixed to the upper surface of the first arm  31  and the proximal end surface of the second arm  32 . Or, as shown in  FIG. 13 , the fixing member  100  may be attached from the upside of the second arm  32  reversely to the embodiment, the wall portions  120 ,  130  and the first arm  31  may be fixed by the fourth screws B 4 , and the wall portions  120 ,  130  and the second arm  32  may be fixed by fifth screws B 5 . 
     The fixing member  100  fixes the first arm  31  and the second arm  32  in an attitude extending straight. In a general scalar robot, the attitude is a reference position, i.e., an attitude in which the pivot angle of the second arm  32  relative to the first arm  31  is 0°. Accordingly, with the first arm  31  and the second arm  32  fixed in the attitude, attachment and detachment of the joint actuator  52  are performed, and thereby, resetting or the like of the joint actuator  52  is easier. 
     Note that the attitude of the first arm  31  and the second arm  32  is not particularly limited. When it is difficult to set the first arm  31  and the second arm  32  to extend straight due to e.g. a problem of the work space or the like, an attitude in which the second arm  32  bends relative to the first arm  31  (an attitude at pivot angle≠0) may be set. In this attitude, the center of gravity of the robot  1  is closer to the base  2  side than that in the attitude in which the first arm  31  and the second arm  32  extend straight. Therefore, when the joint actuator  52  is attached and detached, the load applied to the robot  1  may be reduced. 
     Next, the joint actuator  51  will be briefly explained. As described above, the joint actuator  51  has the same configuration as the joint actuator  52 , but mainly differs in position. As shown in  FIG. 14 , the joint actuator  51  is placed to be vertically inverted to the joint actuator  52 , and the flange  9  is fixed to a second mounting surface  21  of the base  2 . An opening  22  is formed in the base  2 , the wave gearing  7  projects upward via the opening  22 , and the coupling portion  761  of the circular spline  76  is fixed to a first mounting surface  313  of the first arm  31 . The second mounting surface  21  and the first mounting surface  313  each face downward. 
     The attachment and the detachment of the joint actuator  51  are the same as those of the joint actuator  52  and will be briefly explained without illustration. First, the base  2  and the first arm  31  are fixed using a fixing member  100 A. Then, the second screws B 2  are approached from the upside of the first arm  31  and the second screws B 2  are detached. Then, the first screws B 1  are approached from the downside of the base  2  and the first screws B 1  are detached. Then, the joint actuator  51  is pulled out downward and the joint actuator  51  is detached from the robot  1 . Thereby, the detachment of the joint actuator  51  is completed. 
     The attachment method for the joint actuator  51  has a reverse procedure to the above described detachment method. That is, first, the joint actuator  51  is entered from the downside of the base  2  and mounted on the second mounting surface  21 . Thereby, the wave gearing  7  projects upward via the opening  22  and the coupling portion  761  contacts the first mounting surface  313  of the first arm  31 . Then, the flange  9  is approached from the downside and the flange  9  is fixed to the base  2  using the first screws B 1 . Then, the coupling portion  761  is approached from the upside, and the coupling portion  761  is fixed to the first arm  31  by the second screws B 2 . Thereby, the attachment of the joint actuator  51  is completed. 
     According to the above described steps, the joint actuator  51  may be easily attached and detached. Particularly, unlike the related art, the motor  6  and the wave gearing  7  may be integrally attached at the same time, and extremely high work efficiency may be exerted. 
     Next, the above described fixing member  100 A will be explained. As shown in  FIG. 15 , the fixing member  100 A has an L-shape and includes a bottom portion  110 A and a wall portion  120 A stood from an end of the bottom portion  110 A. The fixing member  100 A is attached from the upside, the bottom portion  110 A is fixed to the upper surface of the base  2  by a sixth screw B 6 , and the wall portion  120 A is fastened to the proximal end surface of the first arm  31  by a seventh screw B 7 . Thereby, the base  2  and the first arm  31  are fixed by the fixing member  100 A. 
     Note that the fixing member  100 A is not particularly limited as long as the member may fix the base  2  and the first arm  31 . For example, as shown in  FIG. 16 , the fixing member  100 A may be attached from the downside, the bottom portion  110 A may be fastened to the side surface of the base  2  by the sixth screw B 6 , and the wall portion  120 A may be fastened to the lower surface of the first arm  31  by the seventh screw B 7 . 
     As above, the robot  1  is explained. As described above, the robot  1  has the first arm  31  as a first member having the first mounting surface  311 , the second arm  32  having the opening  322  located at the first mounting surface  311  side with respect to the first arm  31  and facing the first arm  31  and the second mounting surface  321  located at the opposite side to the first arm  31 , and the joint actuator  52  coupling the first arm  31  and the second arm  32  and relatively pivoting the first arm  31  and the second arm  32 . Further, the joint actuator  52  has the flange  9  fixed to the second mounting surface  321 , the motor  6  placed at the opposite side to the first arm  31  with respect to the flange  9 , and the wave gearing  7  as the reducer placed at the first arm  31  side with respect to the flange  9 , projecting from the opening  322  to the first arm  31  side, and fixed to the first mounting surface  311 . The width W 3  of the opening  322  is smaller than the width W 9  of the flange  9 , the width W 6  of the motor  6  is smaller than the width W 9  of the flange  9 , the width W 7  of the wave gearing  7  is smaller than the width W 3  of the opening  322 . The joint actuator  52  is mounted on the second mounting surface  321  from the opposite side to the first arm  31 , and thereby, the wave gearing  7  is projected from the opening  322  to the first arm  31  side. The flange  9  is fastened to the second arm  32  from the opposite side to the first arm  31  using the first screws B 1 , the wave gearing  7  is fastened to the first arm  31  from the opposite side to the second arm  32  using the second screws B 2 , and thereby, the first arm  31  and the second arm  32  are coupled. According to the structure, the joint actuator  52  may be detached from the robot  1  with the motor  6  and the wave gearing  7  remaining integrated by detachment of the first screws B 1  and the second screws B 2 . On the other hand, the joint actuator  52  may be attached to the robot  1  with the motor  6  and the wave gearing  7  remaining integrated. Accordingly, the higher work efficiency may be exerted. Note that, here, the configuration in which the first member is the first arm  31 , the second member is the second arm  32 , and the joint actuator is the joint actuator  52  is described, however, the same applies to the configuration in which the first member is the first arm  31 , the second member is the base  2 , and the joint actuator is the joint actuator  51  (the same applies to the following description). 
     As described above, the attachment method for the joint actuator  52  is the attachment method for the joint actuator  52  coupling the first arm  31  as the first member having the first mounting surface  311  and the second arm  32  as the second member having the opening  322  located at the first mounting surface  311  side with respect to the first arm  31  and facing the first arm  31  and the second mounting surface  321  located at the opposite side to the first arm  31 , and relatively pivoting the first arm  31  and the second arm  32 . The joint actuator  52  has the flange  9  fixed to the second mounting surface  321 , the motor  6  placed at the opposite side to the first arm  31  with respect to the flange  9 , and the wave gearing  7  as the reducer placed at the first arm  31  side with respect to the flange  9 , projecting from the opening  322  to the first arm  31  side, and fixed to the first mounting surface  311 . The width W 3  of the opening  322  is smaller than the width W 9  of the flange  9 , the width W 6  of the motor  6  is smaller than the width W 9  of the flange  9 , and the width W 7  of the wave gearing  7  is smaller than the width W 3  of the opening  322 . The method includes mounting the joint actuator  52  on the second mounting surface  321  from the opposite side to the first arm  31  and projecting the wave gearing  7  from the opening  322  to the first arm  31  side, fastening the flange  9  to the second arm  32  from the opposite side to the first arm  31  using the first screws B 1 , and fastening the wave gearing  7  to the first arm  31  from the opposite side to the second arm  32  using the second screws B 2 . According to the attachment method, the joint actuator  52  may be attached to the robot  1  with the motor  6  and the wave gearing  7  remaining integrated. Accordingly, the higher work efficiency may be exerted. 
     As described above, in the attachment method for the joint actuator  52 , the joint actuator  52  is attached with the first arm  31  and the second arm  32  fixed by the fixing member  100 . Thereby, the attachment of the joint actuator  52  is easier. Further, the relative position of the first arm  31  and the second arm  32  does not shift and calibration of the encoder  8  after attachment of the joint actuator  52  is unnecessary. Therefore, efforts for replacement or maintenance may be reduced and operation of the robot  1  may be restarted earlier after attachment of the joint actuator  52 . 
     As described above, the detachment method for the joint actuator  52  is the detachment method for the joint actuator  52  coupling the first arm  31  as the first member having the first mounting surface  311  and the second arm  32  as the second member having the opening  322  located at the first mounting surface  311  side with respect to the first arm  31  and facing the first arm  31  and the second mounting surface  321  located at the opposite side to the first arm  31 , and relatively pivoting the first arm  31  and the second arm  32 . The joint actuator  52  has the flange  9  fixed to the second mounting surface  321 , the motor  6  placed at the opposite side to the first arm  31  with respect to the flange  9 , and the wave gearing  7  as the reducer placed at the first arm  31  side with respect to the flange  9 , projecting from the opening  322  to the first arm  31  side, and fixed to the first mounting surface  311 . The width W 3  of the opening  322  is smaller than the width W 9  of the flange  9 , the width W 6  of the motor  6  is smaller than the width W 9  of the flange  9 , and the width W 7  of the wave gearing  7  is smaller than the width W 3  of the opening  322 . The flange  9  is fastened to the second arm  32  from the opposite side to the first arm  31  by the first screws B 1 , and the wave gearing  7  is fastened to the first arm  31  from the opposite side to the second arm  32  by the second screws B 2 . The method includes removing the second screws B 2 , removing the first screws B 1 , and pulling out the joint actuator  52  to the opposite side to the first arm  31 . According to the detachment method, the joint actuator  52  may be detached from the robot  1  with the motor  6  and the wave gearing  7  remaining integrated. Accordingly, the higher work efficiency may be exerted. 
     As described above, in the detachment method for the joint actuator  52 , the joint actuator  52  is detached with the first arm  31  and the second arm  32  fixed by the fixing member  100 . Thereby, the detachment of the joint actuator  52  is easier. 
     As described above, the fixing member  100  fixing the first arm  31  and the second arm  32  when the joint actuator  52  is detached from the robot  1  or when the joint actuator  52  is attached to the robot  1  having the first arm  31  as the first member, the second arm  32  as the second member, and the joint actuator  52  coupling the first arm  31  and the second arm  32  and relatively pivoting the first arm  31  and the second arm  32 , includes the first insertion hole  111  through which the fourth screw B 4  as a screw used for fixing to the first arm  31  is inserted, and the second insertion holes  121 ,  131  through which the fifth screws B 5  as screws for fixing to the second arm  32  are inserted. Thereby, the first arm  31  and the second arm  32  may be fixed by the simpler configuration. 
     As described above, the fixing member  100  does not overlap with the work paths L 1  for attachment and detachment of the second screws B 2  fixing the first arm  31  and the joint actuator  52  or does not overlap with the work paths L 2  for attachment and detachment of the first screws B 1  fixing the second arm  32  and the joint actuator  52 . Thereby, the attachment and the detachment of the first screws B 1  and the second screws B 2  are not hindered by the fixing member  100 , and the attachment and the detachment of the first screws B 1  and the second screws B 2  may be smoothly performed. 
     As described above, the fixing member  100  has the positioning portions  128 ,  138  for positioning with respect to the robot  1 . Thereby, the attachment of the fixing member  100  to the robot  1  is easier. 
     As described above, the maintenance system used for the robot  1  fixes the first arm  31  and the second arm  32  by the fixing member  100  when the joint actuator  52  is detached from the robot  1  or when the joint actuator  52  is attached to the robot  1  having the first arm  31  as the first member, the second arm  32  as the second member, and the joint actuator  52  coupling the first arm  31  and the second arm  32  and relatively pivoting the first arm  31  and the second arm  32 . Thereby, the first arm  31  and the second arm  32  do not shift during work, and the attachment and the detachment of the joint actuator  52  may be easily performed. 
     As above, the robot, the attachment method, the detachment method, the fixing member, and the maintenance system according to the present disclosure are explained based on the illustrated embodiments, however, the present disclosure is not limited to those. The configurations of the respective parts may be replaced by any configurations having the same functions. Or, any other configuration may be added to the present disclosure.