Abstract:
A horizontal multi-joint robot includes: a first joint capable of swiveling around a first axis; a second joint capable of swiveling around a second axis that is parallel to and spaced apart from the first axis; and a duct connected between the first joint and the second joint. The first joint has a first connecting portion forming a predetermined angle relative to the first axis. The second joint has a second connecting portion forming a predetermined angle relative to the second axis. The duct has a first end and a second end. The first end is connected to the first connecting portion. The second end is connected to the second connecting portion.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a horizontal multi-joint robot and a robot. 
         [0003]    2. Related Art 
         [0004]    JP-A-2009-226567 describes a horizontal multi-joint robot (SCARA robot) according to the related art. The horizontal multi-joint robot described in JP-A-2009-226567 has a pedestal, a first arm mounted on the pedestal so that the first arm can swivel (i.e., turn, rotate or pivot), a second arm mounted on the first arm so that the second arm can swivel, a work head mounted on the second arm, and a harness (duct) with one side thereof mounted on the pedestal and the other side thereof mounted on the second arm. Wires and pipes connected to a second arm drive motor and a work head drive motor are housed inside the harness. Such a horizontal multi-joint robot of JP-A-2009-226567 has, for example, the following two problems. 
         [0005]    The first problem is that driving of the horizontal multi-joint robot causes the harness to shake and thus generates unwanted vibration. Specifically, in the horizontal multi-joint robot of JP-A-2009-226567, the root of the harness on the pedestal side is shifted from the axis of the first arm and the root of the harness on the second arm side is shifted from the axis of the second arm. Therefore, when the first and second arms swivel, the distance between both roots of the harness changes and this change causes the harness to deform and vibrate unnecessarily. Also, the swiveling of the first and second arms causes the harness to twist and vibrate unnecessarily. Such unnecessary vibration of the harness causes deterioration in the vibration damping of the horizontal multi-joint robot (increases the time required for the vibration to subside to a predetermined magnitude). 
         [0006]    The second problem is that the horizontal multi-joint robot is increased in size. Specifically, the harness has a large height since both ends of the harness extend directly upward so as to coincide with the axes of the first and second arms. Therefore, a large space is required to place the harness which increases the size of the horizontal multi-joint robot. 
       SUMMARY 
       [0007]    An advantage of some aspects of the invention is that a horizontal multi-joint robot and a robot in which vibration of the duct at the time of driving can be restrained and the installation space of the duct can be reduced. 
         [0008]    An aspect of the disclosure is directed to a horizontal multi-joint robot including: a first joint capable of swiveling around a first axis; a second joint capable of swiveling around a second axis that is parallel to the first axis and spaced apart from the first axis; and a duct connected to the first joint and the second joint. The first joint is provided with a first connecting portion forming a predetermined angle relative to the first axis. The second joint is provided with a second connecting portion forming a predetermined angle relative to the second axis. The duct has a first end and a second end. The first end is connected to the first connecting portion. The second end is connected to the second connecting portion. 
         [0009]    With this configuration, a horizontal multi-joint robot is provided in which vibration of the duct at the time of driving can be restrained and the installation space of the duct can be reduced. 
         [0010]    In the horizontal multi-joint robot of the aspect of the disclosure, it is preferable that the first connecting portion is inclined toward the second axis and that the second connecting portion is inclined toward the first axis. 
         [0011]    With this configuration, the total length of the duct can be reduced and the curvature of the duct can be restrained to a small value. Therefore, vibration of the duct at the time when the first and second arms are driven or when the driving is stopped can be prevented or restrained. 
         [0012]    In the horizontal multi-joint robot of the aspect of the disclosure, it is preferable that a duct connecting portion of the first joint and a duct connecting portion of the second joint are provided within the same plane as the normals of the first axis and the second axis. 
         [0013]    With this configuration, the curvature of the duct can be made substantially constant along the axial direction. That is, the concentration of a bending stress on a predetermined part of the duct can be prevented or restrained. 
         [0014]    In the horizontal multi-joint robot of the aspect of the disclosure, it is preferable that, if a center axis of the first connecting portion is a third axis, a center axis of the second connecting portion is a fourth axis, an angle formed by the third axis and the first axis is θ1, and an angle formed by the fourth axis and the second axis is θ2, a relation of θ1=θ2 is satisfied. 
         [0015]    With this configuration, the curvature of the duct can be made substantially constant along the axial direction. That is, the concentration of a bending stress on a predetermined part of the duct can be prevented or restrained. 
         [0016]    In the horizontal multi-joint robot of the aspect of the disclosure, it is preferable that, if a center axis of the first connecting portion is a third axis, a center axis of the second connecting portion is a fourth axis, an angle formed by the third axis and the first axis is θ1, and an angle formed by the fourth axis and the second axis is θ2, each of the angles θ1 and θ2 is 10° or greater and 60° or smaller. 
         [0017]    With this configuration, the maximum height of the duct can be restrained and flexure of the first and second joints can also be restrained. Therefore, the curvature of wires within the first and second joints can be reduced and a bending stress applied to the wires can be reduced. 
         [0018]    In the horizontal multi-joint robot of the aspect of the disclosure, it is preferable that the first joint and the second joint have the same shape and size. 
         [0019]    Thus, the device design is simplified. 
         [0020]    In the horizontal multi-joint robot of the aspect of the disclosure, it is preferable that, if a center axis of the first connecting portion is a third axis, and the center axis of the second connecting portion is a fourth axis, the duct extends along a circle having both the third axis and the fourth axis as tangents. 
         [0021]    With this configuration, since an equal bending stress is applied to substantially the entire area of the duct, local concentration of stress on a predetermined part of the duct can be securely prevented. 
         [0022]    In the horizontal multi-joint robot of the aspect of the disclosure, it is preferable that, if a distance between the first axis and the second axis is L, an average radius of curvature R of the duct satisfies a relation of 0.6L≦R≦L. 
         [0023]    With this configuration, excessive flexure of the duct is restrained. Therefore, the bending strength required of the duct can be lowered and, for example, a reduction in the weight of the duct due to a reduced thickness or the like can be realized. 
         [0024]    In the horizontal multi-joint robot of the aspect of the disclosure, it is preferable that, if a distance between the first axis and the second axis is L, a relation of 100 mm≦L≦2000 mm is satisfied. 
         [0025]    With this configuration, the total length of the duct can be restrained and the curvature of the duct can also be reduced. Moreover, the duct can be effectively reduced in weight. 
         [0026]    Another aspect of the disclosure is directed to a robot including: a pedestal; a first arm connected to the pedestal and capable of swiveling around a first axis in relation to the pedestal; a second arm connected to the first arm and capable of swiveling around a second axis that is parallel to the first axis and spaced apart from the first axis, in relation to the first arm; and a wiring section which accommodates a wire therein and conveys the wire from the second arm to the pedestal. The wiring section includes: a duct supporting portion provided to protrude from the pedestal and intersect with the first axis; a first joint connected to the duct supporting portion and capable of swiveling around the first axis in relation to the duct supporting portion; a second joint connected to the second arm and capable of swiveling around the second axis in relation to the second arm; and a duct connected to the first joint and the second joint. The first joint is provided with a first connecting portion forming a predetermined angle relative to the first axis. The second joint is provided with a second connecting portion forming a predetermined angle relative to the second axis. The duct has a first end and a second end. The first end is connected to the first connecting portion. The second end is connected to the second connecting portion. 
         [0027]    With this configuration, a robot is provided in which vibration of the duct at the time of driving can be restrained and the installation space of the duct can be reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    Embodiments of the invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
           [0029]      FIG. 1  is a view showing a preferred embodiment of a horizontal multi-joint robot. 
           [0030]      FIG. 2  is an enlarged sectional view of a wiring section provided in the horizontal multi-joint robot shown in  FIG. 1 . 
           [0031]      FIG. 3  is a perspective view showing a preferred embodiment of a robot. 
           [0032]      FIG. 4  is a view showing a first wiring section provided in the robot shown in  FIG. 3 . 
           [0033]      FIG. 5  is a view showing a second wiring section provided in the robot shown in  FIG. 3 . 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0034]    Hereinafter, a preferred embodiment of a horizontal multi-joint robot and a robot will be described in detail with reference to the drawings. 
       Horizontal Multi-Joint Robot 
       [0035]    First, a horizontal multi-joint robot will be described. 
         [0036]      FIG. 1  is a view showing a preferred embodiment of a horizontal multi-joint robot.  FIG. 2  is an enlarged sectional view of a wiring section provided in the horizontal multi-joint robot shown in  FIG. 1 . 
         [0037]    As shown in  FIG. 1 , a horizontal multi-joint robot (SCARA robot: horizontal multi-joint robot)  100  has a pedestal  110 , a first arm  120 , a second arm  130 , a work head  140 , an end effector  150 , and a wiring section  160 . The horizontal multi-joint robot  100  is a representative example of a horizontal multi-joint robot and also a robot. 
         [0038]    The pedestal  110  is fixed, for example, to a floor surface, not shown, with bolts or the like. The first arm  120  is connected to an upper end of the pedestal  110 . The first arm  120  is capable of swiveling around a first axis J1 that extends along a vertical direction, in relation to the pedestal  110 . 
         [0039]    Inside the pedestal  110 , a first motor  111  which causes the first arm  120  to swivel, and a first decelerator  112  are installed. An input axis of the first decelerator  112  is connected to a rotation axis of the first motor  111 . An output axis of the first decelerator  112  is connected to the first arm  120 . Therefore, when the first motor  111  is driven and a driving force thereof is transmitted to the first arm  120  via the first decelerator  112 , the first arm  120  swivels within a horizontal plane around the first axis J1 in relation to the pedestal  110 . The first motor  111  is provided with a first encoder  113  which outputs a pulse signal corresponding to the amount of rotation of the first motor  111 . Based on the pulse signal from the first encoder  113 , driving (amount of swiveling) of the first arm  120  in relation to the pedestal  110  can be detected. 
         [0040]    The second arm  130  is connected to a distal end of the first arm  120 . The second arm  130  is capable of swiveling around a second axis J2 that extends along a vertical direction, in relation to the first arm  120 . 
         [0041]    Inside the second arm  130 , a second motor  131  which causes the second arm  130  to swivel, and a second decelerator  132  are installed. An input axis of the second decelerator  132  is connected to a rotation axis of the second motor  131 . An output axis of the second decelerator  132  is connected and fixed to the first arm  120 . Therefore, when the second motor  131  is driven the a driving force thereof is transmitted to the first arm  120  via the second decelerator  132 , the second arm  130  swivels within a horizontal plane around the second axis J2 in relation to the first arm  120 . The second motor  131  is provided with a second encoder  133  which outputs a pulse signal corresponding to the amount of rotation of the second motor  131 . Based on the pulse signal from the second encoder  133 , driving (amount of swiveling) of the second arm  130  in relation to the first arm  120  can be detected. 
         [0042]    The work head  140  is arranged at a distal end of the second arm  130 . The work head  140  has a spline nut  141  and a ball screw nut  142  that are coaxially arranged at the distal end of the second arm  130 , and a spline shaft  143  inserted in the spline nut  141  and the ball screw nut  142 . The spline shaft  143  is rotatable around its axis in relation to the second arm  130  and also capable of moving up and down (ascent and descent). 
         [0043]    Inside the second arm  130 , a rotation motor  144  and a lift motor  145  are arranged. A driving force of the rotation motor  144  is transmitted to the spline nut  141  by a driving force transmission mechanism, not shown. As the spline nut  141  rotates forward and backward, the spline shaft  143  rotates forward and backward around an axis J5 that extends along a vertical direction. The rotation motor  144  is provided with a third encoder  146  which outputs a pulse signal corresponding to the amount of rotation of the rotation motor  144 . Based on the pulse signal from the third encoder  146 , the amount of rotation of the spline shaft  143  in relation to the second arm  130  can be detected. 
         [0044]    A driving force of the lift motor  145  is transmitted to the ball screw nut  142  by a driving force transmission mechanism, not shown. As the ball screw nut  142  rotates forward and backward, the spline shaft  143  moves up and down. The lift motor  145  is provided with a fourth encoder  147  which outputs a pulse signal corresponding to the amount of rotation of the lift motor  145 . Based on the pulse signal from the fourth encoder  147 , the amount of movement of the spline shaft  143  in relation to the second arm  130  can be detected. 
         [0045]    The end effector  150  is connected to a distal end (lower end) of the spline shaft  143 . The end effector  150  is not particularly limited and may include, for example, a unit which holds an object to be carried, a unit which processes an object to be processed, or the like. 
         [0046]    Plural wires  170  connected to individual electronic components (for example, the second motor  131 , the rotation motor  144 , the lift motor  145 , the second, third and fourth encoders  133 ,  146 ,  147  and the like) arranged inside the second arm  130  pass through the pipe-like wiring section  160  connecting the second arm  130  and the pedestal  110  to each other and are drawn into the pedestal  110 . Moreover, the plural wires  170  are bundled inside the pedestal  110  and thus drawn up to a control device, not shown, which is installed outside the pedestal  110  and generally controls the horizontal multi-joint robot  100 , along with the wires connected to the first motor  111  and the first encoder  113 . 
         [0047]    Since the wires  170  of the individual electronic components inside the second arm  130  are thus drawn into the pedestal  110  via the wiring section  160 , no space for drawing the wires  170  needs to be secured within the pedestal  110 , the first arm  120  and the second arm  130 . Also, for example, the second motor  131  and the second decelerator  132  need not be hollow in order to draw the wires  170  from the second arm  130  to the first arm  120 , and an increase in the size of the second motor  131  and the second decelerator  132  is restrained. Similarly, for example, the first motor  111  and the first decelerator  112  need not be hollow in order to draw the wires  170  from the first arm  120  to the pedestal  110 , and an increase in the size of the first motor  111  and the first decelerator  112  is restrained. Therefore, the pedestal  110 , the first arm  120 , and the second arm  130  can be reduced in size. Also, the total weight of the pedestal  110 , the first arm  120 , and the second arm  130  (the weight including each internal device) can be restrained. Therefore, a reduction in the size and weight of the horizontal multi-joint robot  100  can be realized. 
         [0048]    As shown in  FIG. 1  and  FIG. 2 , the wiring section  160  has a duct supporting portion  161 , a first joint  162 , a second joint  163 , and a duct  164 . These components are connected in the order of the duct supporting portion  161 , the first joint  162 , the duct  164 , and the second joint  163 , from the side of the pedestal  110 . A wire insertion hole which connects the insides of the pedestal  110  and the second arm  130  to each other is formed within the wiring section  160 . That is, the duct supporting portion  161 , the first joint  162 , the second joint  163 , and the duct  164  are all pipe-shaped and have open inner spaces thereof connected in series. 
         [0049]    The duct supporting portion  161  protrudes from a rear part on a lateral side of the pedestal  110  and extends with a gentle curve up above the pedestal  110 . Also, the duct supporting portion  161  is arranged so that an upper edge of a distal end of the duct supporting portion  161  is substantially at the same height as an upper end of the second arm  130 . The duct supporting portion  161  is rigid and does not substantially flex or deform. 
         [0050]    The first joint  162  is connected to and received by a bearing at the distal end of the duct supporting portion  161  and is capable of swiveling around the first axis J1 in relation to the duct supporting portion  161 . Meanwhile, the second joint  163  is connected to and received by a bearing at a proximal end and upper end of the second arm  130  and is capable of swiveling around the second axis J2 in relation to the second arm  130 . 
         [0051]    In this manner, in the horizontal multi-joint robot  100 , the axis of the first joint  162  coincides with the axis of the first arm  120 , and the axis of the second joint  163  coincides with the axis of the second arm  130 . Therefore, no matter how each of the first and second arms  120 ,  130  is driven, an inter-axis distance between the axes of the first and second joints  162 ,  163  is kept constant. Therefore, deformation (expansion or contraction) of the duct  164  connected to the first and second joints  162 ,  163  is prevented or restrained. Consequently, vibration of the duct  164  at the time when the first and second arms  120 ,  130  are driven or when the driving is stopped can be prevented or restrained, and vibration of the second arm  130  can be reduced accordingly. 
         [0052]    The first joint  162  is bent or curved in the middle in the extending direction. Therefore, it can be said that the first joint  162  has a duct supporting portion connecting portion  162   a  connected to the duct supporting portion  161 , a duct connecting portion (first connecting portion)  162   b  connected to the duct  164 , and a curved portion  162   c  which is situated between the duct supporting portion connecting portion  162   a  and the duct connecting portion  162   b  and connects these portions at a predetermined angle. The duct supporting portion connecting portion  162   a  is provided along a vertical direction, and a center axis thereof coincides with the first axis J1. Meanwhile, the duct connecting portion  162   b  is provided so that a portion of a center axis thereof (third axis) J3 overlapping the duct  164  is inclined toward the second joint  163  in relation to the first axis J1. 
         [0053]    The second joint  163  has the same shape and size as the first joint  162 . That is, the second joint  163  is bent or curved in the middle in the extending direction and has an arm connecting portion  163   a  connected to the second arm  130 , a duct connecting portion (second connecting portion)  163   b  connected to the duct  164 , and a curved portion  163   c  which is situated between the arm connecting portion  163   a  and the duct connecting portion  163   b  and connects these portions at a predetermined angle. The arm connecting portion  163   a  is provided along a vertical direction, and a center axis thereof coincides with the second axis J2. Meanwhile, the duct connecting portion  163   b  is provided so that a portion of a center axis thereof (fourth axis) J4 overlapping the duct  164  is inclined toward the first joint  162  in relation to the second axis J2. 
         [0054]    As described above, since the second joint  163  has the same shape and size as the first joint  162 , the first and second joints  162 ,  163  can be used interchangeably, making it easy to design the horizontal multi-joint robot  100 . Specifically, angles θ1, θ2, described later, can be easily made equal, and the first and second joints  162 ,  163  can be arranged easily at the same height, as described below. 
         [0055]    Also, as described above, since the duct connecting portion  162   b  is inclined toward the second axis J2 and the duct connecting portion  163   b  is inclined toward the first axis J1, the total length of the duct  164  can be restrained and the curvature of the duct can be restrained to a small value. Therefore, vibration of the duct  164  at the time when the first and second arms  120 ,  130  are driven or when the driving is stopped can be prevented or restrained. 
         [0056]    The duct  164  is flexible and has two ends, that is, a first end  164   a  and a second end  164   b . The first end  164   a  is connected to the duct connecting portion  162   b  of the first joint  162 . The second end  164   b  is connected to the duct connecting portion  163   b  of the second joint  163 . 
         [0057]    The duct  164  is straight in its natural state and is connected to the first and second joints  162 ,  163  in a bent and deformed state. Since the duct connecting portions  162   b ,  163   b  of the first and second joints  162 ,  163  are inclined in relation to the first and second axes J1, J2, as described above, upward protrusion of the duct  164  can be restrained (the maximum height T in  FIG. 1  can be restrained to a low value). Therefore, a small and vertically short installation space for the duct  164  suffices and the horizontal multi-joint robot  100  can be reduced in size. Also, since the upward protrusion can be restrained, the total length of the duct  164  can be restrained accordingly. Therefore, vibration of the duct  164  at the time when the first and second arms  120 ,  130  are driven or when the driving is stopped can be prevented or restrained. 
         [0058]    The maximum height T may be preferably as short as possible and, for example, preferably shorter than a maximum reach height at the upper end of the spline shaft  143  (the height of the upper end in the state where the spline shaft  143  is situated the uppermost position). By employing such a height, the horizontal multi-joint robot  100  can be securely reduced in size. 
         [0059]    An average radius of curvature R of the center axis of the duct  164  is not particularly limited. However, it is preferable that the average radius of curvature R satisfies the relation of 0.6L≦R≦L, where the distance between the first axis J1 and the second axis J2 is L. By employing such an average radius of curvature R, excessive curving of the duct  164  is restrained. Therefore, the bending strength required of the duct  164  can be lowered and, for example, a reduction in weight of the duct  164  due to reduced thickness or the like can be realized. 
         [0060]    Also, the distance L between the first and second axes J1, J2 is not particularly limited. However, it is preferable that the distance L satisfies the relation of 100 mm≦L≦2000 mm. By employing such a distance L, the total length of the duct  164  can be restrained and the curvature of the duct  164  can also be reduced. Moreover, the duct  164  can be effectively reduced in weight, and vibration of the duct  164  at the time when the first and second arms  120 ,  130  are driven or when the driving is stopped can be prevented or restrained more effectively. 
         [0061]    Here, it is preferable that an angle θ1 formed by the center axis (third axis) J3 of the duct connecting portion  162   b  and the first axis J1, and an angle θ2 (=θ1) formed by the center axis (fourth axis) J4 of the duct connecting portion  163   b  and the second axis J2 satisfies the relation of 10°≦θ1, θ2≦60°, more preferably 20°≦θ1, θ2≦40°. By employing such a range of θ1, θ2, the maximum height T of the duct  164  can be restrained and excessive curving of the first and second joints  162 ,  163  can be restrained. Therefore, the curvature of the wires  170  in the curved portions  162   c ,  163   c  of the first and second joints  162 ,  163  can be reduced and bending stress applied to the wires  170  can be reduced. Also, since the applied bending stress is reduced, the strength required of the wires  170  is lowered accordingly. Thus, a reduction in diameter of the wires  170  and a reduction in weight due to the reduction in diameter can be realized. 
         [0062]    Moreover, since the curvature of the duct  164  can be reduced, the bending stress applied to the duct  164  can be reduced. Also, since the applied bending stress is reduced, the strength required of the duct  164  is lowered accordingly. Thus, a reduction in thickness of the duct  164  and a reduction in weight due to the reduction in thickness can be realized. 
         [0063]    If θ1, θ2 are below the above lower limit value and the distance L between the first and second axes J1, J2 is short, the duct  164  has a large curvature and processing to increase the strength of the duct  164 , for example, increasing the thickness of the duct  164  or the like may be necessary. On the contrary, if θ1, θ2 exceed the above upper limit value, the wires  170  in the curved portions  162   c ,  163   c  of the first and second joints  162 ,  163  have a small curvature and processing to increase the strength of the wires  170 , for example, increasing the thickness of a coating layer or the like may be necessary. 
         [0064]    In this embodiment, the duct connecting portions  162   b ,  163   b  of the first and second joints  162 ,  163  are arranged at the same height. In other words, the duct connecting portions  162   b ,  163   b  are provided within the same plane as the normals of the first and second axes J1, J2. Moreover, the duct connecting portions  162   b ,  163   b  have the same slope (θ1, θ2), as described above. Therefore, the curvature of the duct  164  can be made substantially constant along the axial direction and the concentration of bending stress on a predetermined part of the duct  164  can be prevented or restrained. Since the part where stress concentrates tends to be the starting point of vibration, by preventing or restraining the concentration of stress, vibration of the duct  164  at the time when the first and second arms  120 ,  130  are driven or stopped can be prevented or restrained more effectively. Also, since the strength required of the duct  164  is lowered, a reduction in thickness of the duct  164  and a reduction weight due to the reduction in thickness can be realized. 
         [0065]    It is preferable that the duct  164  (portions excluding the parts overlapping with the first and second joints  162 ,  163 ) extends so that the center axis thereof is along a circle (circumference) having the center axis J3 of the duct connecting portion  162   b  and the center axis J4 of the duct connecting portion  163   b  as tangents. In such a curved state, an equal bending stress is applied to substantially the entire area of the duct  164  and therefore local concentration of stress on a predetermined part of the duct  164  can be prevented more securely. Therefore, vibration of the duct  164  at the time when the first and second arms  120 ,  130  are driven or stopped can be prevented or restrained more securely. 
         [0066]    Particularly, in this embodiment, since the first and second joints  162 ,  163  have the same shape and size, the duct connecting portions  162   b ,  163   b  can be easily arranged at the same height, for example, by equalizing the installation height of the first and second joints  162 ,  163 . Since the first and second joints  162 ,  163  thus have the same shape and size, components can be made interchangeable. Thus, the manufacturing cost of the horizontal multi-joint robot  100  can be restrained and the horizontal multi-joint robot  100  can be designed easily. 
         [0067]    The above is the description of the horizontal multi-joint robot  100 . 
         [0068]    While the duct  164  is flexible in this embodiment, the duct  164  may be rigid. As described above, the duct  164  does not substantially deform no matter how the first and second arms  120 ,  130  are driven. Therefore, even if the duct  164  is rigid, this does not affect the driving of the horizontal multi-joint robot  100 . If the duct  164  is made of a rigid material, it is preferable that the duct  164  is made of, for example, a metallic material with environmental resistance. Thus, the horizontal multi-joint robot  100  suitable for use in a special environment is provided. 
       Robot 
       [0069]    Next, a robot will be described. 
         [0070]      FIG. 3  is a perspective view showing a preferred embodiment of a robot.  FIG. 4  is a view showing a first wiring section provided in the robot shown in  FIG. 3 .  FIG. 5  is a view showing a second wiring section provided in the robot shown in  FIG. 3 . 
         [0071]    A robot  300  shown in  FIG. 3  is a vertical multi-joint (six-axis) robot having a pedestal  310 , four arms  320 ,  330 ,  340 ,  350 , and a wrist  360  that are connected in order. 
         [0072]    The pedestal  310  is fixed, for example, to a floor surface which is not shown in the drawing with bolts or the like. The arm  320  with an attitude inclined in relation to horizontal direction is connected to an upper end of such a pedestal  310 . The arm  320  is capable of swiveling around an axis J6 that extends along a vertical direction in relation to the pedestal  310 . 
         [0073]    Inside the pedestal  310 , a first motor  311  which causes the arm  320  to swivel, and a first decelerator  312  are installed. Although not shown, an input axis of the first decelerator  312  is connected to a rotation axis of the first motor  311 , and an output axis of the first decelerator  312  is connected to the arm  320 . Therefore, when the first motor  311  is driven and a driving force thereof is transmitted to the arm  320  via the first decelerator  312 , the arm  320  swivels within a horizontal plane around the axis J6 in relation to the pedestal  310 . The first motor  311  is provided with a first encoder  313  which outputs a pulse signal corresponding to the amount of rotation of the first motor  311 . Based on the pulse signal from the first encoder  313 , the amount of swiveling of the arm  320  in relation to the pedestal  310  can be detected. 
         [0074]    The arm  330  is connected to a distal end of the arm  320 . The arm  330  is capable of swiveling around an axis J7 that extends along a horizontal direction in relation to the arm  320 . 
         [0075]    Inside the arm  330 , a second motor  331  which causes the arm  330  to swivel in relation to the arm  320 , and a second decelerator  332  are installed. Although not shown, an input axis of the second decelerator  332  is connected to a rotation axis of the second motor  331 , and an output axis of the second decelerator  332  is connected and fixed to the arm  320 . Therefore, when the second motor  331  is driven and a driving force thereof is transmitted to the arm  320  via the second decelerator  332 , the arm  330  swivels within a horizontal plane around the axis J7 in relation to the arm  320 . The second motor  331  is provided with a second encoder  333  which outputs a pulse signal corresponding to the amount of rotation of the second motor  331 . Based on the pulse signal from the second encoder  333 , the driving (amount of swiveling) of the arm  330  in relation to the arm  320  can be detected. 
         [0076]    The arm  340  is connected to a distal end of the arm  330 . The arm  340  is capable of swiveling around an axis J8 that extends along a horizontal direction in relation to the arm  330 . 
         [0077]    Inside the arm  340 , a third motor  341  which causes the arm  340  to swivel in relation to the arm  330 , and a third decelerator  342  are installed. Although not shown, an input axis of the third decelerator  342  is connected to a rotation axis of the third motor  341 , and an output axis of the third decelerator  342  is connected and fixed to the arm  330 . Therefore, when the third motor  341  is driven and a driving force thereof is transmitted to the arm  330  via the third decelerator  342 , the arm.  340  swivels within a horizontal plane around the axis J8 in relation to the arm.  330 . The third motor  341  is provided with a third encoder  343  which outputs a pulse signal corresponding to the amount of rotation of the third motor  341 . Based on the pulse signal from the third encoder  343 , the driving (amount of swiveling) of the arm  340  in relation to the arm  330  can be detected. 
         [0078]    The arm  350  is connected to a distal end of the arm  340 . The arm  350  is capable of swiveling around an axis J9 that extends along a center axis of the arm  340  in relation to the arm  340 . 
         [0079]    Inside the arm  350 , a fourth motor  351  which causes the arm  350  to swivel in relation to the arm  340 , and a fourth decelerator  352  are installed. An input axis of the fourth decelerator  352  is connected to a rotation axis of the fourth motor  351 , and an output axis of the fourth decelerator  352  is connected and fixed to the arm  340 . Therefore, when the fourth motor  351  is driven and a driving force thereof is transmitted to the arm  340  via the fourth decelerator  352 , the arm  350  swivels within a horizontal plane around the axis J9 in relation to the arm  340 . The fourth motor  351  is provided with a fourth encoder  353  which outputs a pulse signal corresponding to the amount of rotation of the fourth motor  351 . Based on the pulse signal from the fourth encoder  353 , the driving (amount of swiveling) of the arm  350  in relation to the arm  340  can be detected. 
         [0080]    The wrist  360  is connected to a distal end of the arm  350 . The wrist  360  has a ring-shaped support ring connected to the arm  350 , and a cylindrical wrist main body supported on a distal end of the support ring. A distal end surface of the wrist main body is a flat surface and serves, for example, as a mounting surface where a manipulator holding a precision device such as a wristwatch is mounted. 
         [0081]    The support ring is capable of swiveling around an axis J10 that extends along a horizontal direction in relation to the arm  350 . The wrist main body is capable of swiveling around an axis J11 that extends along a center axis of the wrist main body in relation to the support ring. 
         [0082]    Inside the arm  350 , a fifth motor  354  which causes the support ring to swivel in relation to the arm  350 , and a sixth motor  355  which causes the wrist main body to swivel in relation to the support ring are arranged. Driving forces of the fifth and sixth motors  354 ,  355  are transmitted to the support ring and the wrist main body, respectively, by a driving force transmission mechanism, not shown. The fifth motor  354  is provided with a fifth encoder  356  which outputs a pulse signal corresponding to the amount of rotation of the fifth motor  354 . Based on the pulse signal from the fifth encoder  356 , the amount of swiveling of the support ring in relation to the arm  350  can be detected. Also, the sixth motor  355  is provided with a sixth encoder  357  which outputs a pulse signal corresponding to the amount of rotation of the sixth motor  355 . Based on the pulse signal from the sixth encoder  357 , the amount of swiveling of the wrist main body in relation to the support ring can be detected. 
         [0083]    Plural wires  370  connected to individual electronic components (for example, third, fourth, fifth and sixth motors  341 ,  351 ,  354 ,  355 , third, fourth, fifth and sixth encoders  343 ,  353 ,  356 ,  357  and the like) arranged insides the arms  340 ,  350  pass through a pipe-like first wiring section  380  connecting the arm  340  and the arm  330  to each other and are drawn into the arm  340 . Also, the plural wires  370  pass through a pipe-like second wiring section  390  connecting the arm  330  and the arm  320  to each other and are drawn into the arm  320 . Moreover, the plural wires  370  are bundled inside the arm  320  and thus drawn to the pedestal  310  together with wires connected to the second motor  331  and the second encoder  333 . The wires are then bundled inside the pedestal  310  and thus drawn up to a control device, not shown, which is installed outside the pedestal  310  and generally controls the robot  300 , along with the wires connected to the first motor  311  and the first encoder  313 . 
         [0084]    Since the wires  370  of the individual electronic components inside the arms  340 ,  350  are thus drawn into the pedestal  310  via the first and second wiring sections  380 ,  390 , a large space for drawing the wires  370  need not be secured within the arms  320 ,  330 . Therefore, as in the foregoing horizontal multi-joint robot  100 , a reduction in the size and weight of the robot  300  can be realized. 
         [0085]    As shown in  FIG. 4 , the first wiring section  380  has a first joint  382 , a second joint  383 , and a duct  384 . These components are connected in order of the first joint  382 , the duct  384 , and the second joint  383 , from the side of the arm  330 . A wire insertion hole (not shown) which connects the insides of the arm  330  and the arm  340  to each other is formed within the first wiring section  380 . That is, the first joint  382 , the second joint  383 , and the duct  384  are all pipe-shaped and have open inner spaces thereof connected in series. 
         [0086]    The first joint  382  is received by a bearing on the arm  330  and is capable of swiveling around an axis J12 in relation to the arm  330 . Meanwhile, the second joint  383  is received by a bearing on the arm  340  and is capable of swiveling around the axis J8 in relation to the arm  340 . The axis J12 is parallel to the axis J8. Therefore, no matter how the arm  340  is driven in relation to the arm  330 , a distance between the axes of the first and second joints  382 ,  383  is kept constant. Therefore, deformation (expansion or contraction) of the duct  384  connected at both ends to the first and second joints  382 ,  383  is prevented or restrained. Consequently, vibration of the duct  384  at the time when the arm  340  is driven or when the driving is stopped can be prevented or restrained. 
         [0087]    The first joint  382 , the second joint  383  and the duct  384  have similar configurations to the first joint  162 , the second joint  163  and the duct  164  of the foregoing horizontal multi-joint robot  100 , respectively, and therefore will not be described further in detail. Also, with respect to the first wiring section  380 , the arm  330 , the arm  340 , the axis J12 and the axis J8 are equivalent to the first arm, the second arm, the first axis and the second axis described in the appended claims, respectively. 
         [0088]    As shown in  FIG. 5 , the second wiring section  390  has a first joint  392 , a second joint  393 , and a duct  394 . These components are connected in order of the first joint  392 , the duct  394 , and the second joint  393 , from the side of the arm  320 . A wire insertion hole (not shown) which connects the insides of the arm  320  and the arm  330  to each other is formed within the second wiring section  390 . That is, the first joint  392 , the second joint  393 , and the duct  394  are all pipe-shaped and have open inner spaces thereof connected in series. 
         [0089]    The first joint  392  is received by a bearing on the arm  320  and is capable of swiveling around an axis J13 in relation to the arm  320 . Meanwhile, the second joint  393  is received by a bearing on the arm  330  and is capable of swiveling around the axis J7 in relation to the arm  330 . The axis J13 is parallel to the axis J7. Therefore, no matter how the arm  330  is driven in relation to the arm  320 , a distance between the axes of the first and second joints  392 ,  393  is kept constant. Therefore, deformation (expansion or contraction) of the duct  394  connected at both ends to the first and second joints  392 ,  393  is prevented or restrained. Consequently, vibration of the duct  394  at the time when the arm  330  is driven or when the driving is stopped can be prevented or restrained. 
         [0090]    The first joint  392 , the second joint  393  and the duct  394  have similar configurations to the first joint  382 , the second joint  383  and the duct  384 , respectively, and therefore will not be described further in detail. Also, with respect to the second wiring section  390 , the arm  320 , the arm  320 , the axis J13 and the axis J7 are equivalent to the first arm, the second arm, the first axis and the second axis described in the appended claims, respectively. 
         [0091]    The above is the description of the robot  300 . 
         [0092]    A horizontal multi-joint robot and a robot are described above, based on the illustrated embodiments. However, the invention is not limited to these embodiments and the configuration of each part can be replaced by an arbitrary configuration having similar functions. Also, other arbitrary components may be added within the scope of the invention. 
         [0093]    The entire disclosure of Japanese Patent Application No. 2012-233499 filed Oct. 23, 2012 is hereby expressly incorporated by reference herein.