Patent Publication Number: US-2019193277-A1

Title: Robot and method of operating the same

Description:
TECHNICAL FIELD 
     The present disclosure relates to a robot and a method of operating the same. 
     BACKGROUND ART 
     Object transferring devices have been known as a device which uses a hand part provided to a tip-end part of a robot to grip and move an object (e.g., see Patent Document 1). In an object transferring device disclosed in Patent Document 1, a notch is formed in a side surface of a bucket which accommodates a group of objects to be transported by a parallel robot, and a hand part moves inside the notch to enter into the bucket smoothly. 
     REFERENCE DOCUMENT OF CONVENTIONAL ART 
     Patent Document 
     [Patent Document 1] JP2016-88721A 
     DESCRIPTION OF THE DISCLOSURE 
     Problems to be Solved by the Disclosure 
     However, in the object transferring device disclosed in Patent Document 1, in order for the hand part to enter into the bucket smoothly, since the special bucket of which the side surface is formed with the notch, there is still room for an improvement. 
     The present disclosure is to solve the conventional problems, and one purpose thereof is to provide a robot and a method of operating the same, which can easily hold and move an object having a cylindrical shape. 
     SUMMARY OF THE DISCLOSURE 
     In order to solve the problem, a robot according to one aspect of the present disclosure includes a first arm provided with a first holding part having a contact surface formed so as to conform to the shape of an outer circumferential surface of a cylindrical workpiece, and a second arm provided with a second holding part formed into one of a plate shape and a bar shape. 
     Thus, the object having the cylindrical shape can be held and moved easily. 
     A method of operating a robot according to another aspect of the present disclosure is a method of operating a robot having a first arm and a second arm. The first arm is provided with a first holding part having a contact surface formed so as to conform to the shape of an outer circumferential surface of a cylindrical workpiece, and the second arm is provided with a second holding part formed into one of a plate shape and a bar shape. The method includes (A) operating the first arm so that the contact surface of the first holding part contacts the outer circumferential surface of the cylindrical workpiece, (B) operating the second arm so that the second holding part contacts an opening part of the cylindrical workpiece, and (C) operating at least one of the first arm and the second arm so that the first holding part and the second holding part approach each other after performing the (A) and (B). 
     Thus, the object having the cylindrical shape can be held and moved easily. 
     Effect of the Disclosure 
     According to the robot and the method of operating the robot of the present disclosure, the object having the cylindrical shape can be held and moved easily. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view illustrating an outline configuration of a robot according to Embodiment 1. 
         FIG. 2  is a schematic view illustrating operation when the robot illustrated in  FIG. 1  holds and conveys a cylindrical workpiece. 
         FIG. 3  is a functional block diagram schematically illustrating a configuration of a robot control device illustrated in  FIG. 1 . 
         FIG. 4  is a schematic view illustrating an outline configuration of a left-side side surface of a first hand part in the robot illustrated in  FIG. 1 . 
         FIG. 5  is a cross-sectional view of a first holding part in the first hand part illustrated in  FIG. 4 , taken along a line A-A. 
         FIG. 6  is a schematic view illustrating an outline configuration of a right-side side surface of a second hand part in the robot illustrated in  FIG. 1 . 
         FIG. 7  is a front view of a second holding part in the second hand part illustrated in  FIG. 6 . 
         FIG. 8  is a flowchart illustrating one example of operation of the robot according to Embodiment 1. 
         FIG. 9  is a schematic view illustrating a state of the robot when the robot operates in accordance with the flowchart illustrated in  FIG. 8 . 
         FIG. 10  is a schematic view illustrating a state of the robot when the robot operates in accordance with the flowchart illustrated in  FIG. 8 . 
         FIG. 11  is a schematic view illustrating a state of the robot when the robot operates in accordance with the flowchart illustrated in  FIG. 8 . 
         FIG. 12  is a schematic view illustrating an outline configuration of a first hand part of a robot of Modification 1 in Embodiment 1. 
         FIG. 13  is a schematic view illustrating an outline configuration of a second hand part of a robot of Modification 2 in Embodiment 1. 
     
    
    
     MODES FOR CARRYING OUT THE DISCLOSURE 
     Hereinafter, one embodiment of the present disclosure is described with reference to the drawings. Note that, throughout the drawings, the same or corresponding parts are denoted with the same reference characters to omit redundant description. Moreover, throughout the drawings, elements for illustrating the present disclosure are extracted, and illustration of other elements may be omitted. Further, the present disclosure is not limited to the following embodiment. 
     Embodiment 1 
     A robot according to Embodiment 1 includes a first arm provided with a first holding part having a contact surface formed so as to conform to the shape of an outer circumferential surface of a cylindrical workpiece, and a second arm provided with a second holding part formed into a plate or bar shape. 
     Alternatively, in the robot according to Embodiment 1, the contact surface of the first holding part may be formed so as to be inclined from one end to the other end. 
     Alternatively, in the robot according to Embodiment 1, an elastic member may be provided to the contact surface of the first holding part. 
     Alternatively, in the robot according to Embodiment 1, a protrusion may be formed in the second holding part. 
     Alternatively, in the robot according to Embodiment 1, a tip-end part of the second holding part may be formed in a tapered shape so that the thickness is reduced toward the tip end. 
     Alternatively, in the robot according to Embodiment 1, the second holding part may be formed in a plate shape, and the protrusion may be formed so as to conform to the shape of an opening part of the cylindrical workpiece when seen in a normal direction of a principal surface of the second holding part. 
     Alternatively, the robot according to Embodiment 1 may further include a control device which causes the first arm to operate so that the contact surface of the first holding part contacts the outer circumferential surface of the cylindrical workpiece, and the second arm to operate so that the second holding part contacts the opening part of the cylindrical workpiece, and then causes at least one of the first arm and the second arm to operate so that the first holding part and the second holding part approach each other. 
     Below, one example of the robot according to Embodiment 1 is described with reference to  FIGS. 1 to 11 . 
     [Structure of Robot] 
       FIG. 1  is a schematic view illustrating an outline configuration of the robot according to Embodiment 1.  FIG. 2  is a schematic view illustrating operation of the robot illustrated in  FIG. 1  when the robot holds and conveys the cylindrical workpiece.  FIG. 3  is a functional block diagram schematically illustrating a configuration of a robot control device illustrated in  FIG. 1 . 
     Note that, in  FIG. 1 , up-and-down directions and left-and-right directions of the robot are expressed as up-and-down directions and left-and-right directions in the figure. Moreover, in  FIG. 2 , the front-and-rear directions and the left-and-right directions of the robot are expressed as front-and-rear directions and left-and-right directions in the figure. 
     As illustrated in  FIGS. 1 and 2 , the robot  100  according to Embodiment 1 includes a first arm  13 A and a second arm  13 B, and a control device  11 . The robot  100  is configured so that the first arm  13 A and the second arm  13 B hold and convey a cylindrical workpiece  202 . Moreover, the robot  100  is configured so that the control device  11  executes an automatic operation of the robot  100  by being taught by an operator, necessary information using an appropriate device. 
     First, a configuration of each instrument disposed in a workspace where the robot  100  according to Embodiment 1 performs a work is described with reference to  FIG. 2 . 
     As illustrated in  FIG. 2 , in the workspace where the robot  100  according to Embodiment 1 performs a work, a box (e.g., cardboard box)  201 , the workpieces  202 , a pedestal  203 , an imaging device  204 , and a belt conveyor  205  are disposed. The box  201  is disposed on an upper surface of the pedestal  203  with the top being opened. 
     In an interior space of the box  201 , the workpieces  202  are accommodated in a parallel stacked manner. For example, each workpiece  202  is put over sideways so that an axial center of the workpiece  202  is oriented in the left-and-right directions, and stacked workpieces  202  are accommodated in the box  201  so as to be placed in order in the front-and-rear directions. Note that, below, the stacked workpieces  202  may also be referred to as the “workpiece stacked body  202 A.” 
     The workpiece  202  is formed in a substantially cylindrical shape, one opening part is opened, and the other opening part is closed. Moreover, the workpiece  202  is formed so that the opening part area is reduced as it goes from one opening part to the other opening part. Note that, below, the other opening part may be referred to as the “bottom.” Moreover, in Embodiment 1, although the workpiece  202  adopts, but not limited to, the form where it is formed in the cylindrical shape, the form where the cross-sectional shape of the workpiece  202  is formed in a polygonal shape may be adopted. 
     A base-end part of an inverted L-shaped support member  203 A, when seen horizontally, is fixed to the front side of the upper surface of the pedestal  203 . The imaging device  204  is disposed at a tip-end part of the support member  203 A. The imaging device  204  is configured to image the workpieces  202  accommodated in the box  201  from above of the box  201  and the captured image information is outputted to the control device  11  of the robot  100 . Note that the imaging device  204  may be disposed at the robot  100 . 
     The belt conveyor  205  is disposed at the side of the robot  100  (here, left side), and is configured to send the workpiece  202  disposed by the robot  100  on an upper surface of the belt conveyor  205  in the front-and-rear directions. 
     Next, a concrete configuration of the robot  100  is described with reference to  FIGS. 1 and 2 . 
     As illustrated in  FIG. 1 , the robot  100  includes a carriage  12 . Wheels  12   a  and fixing parts  12   b  are provided on a lower surface of the carriage  12 , and the robot  100  is constructed to be movable with the wheels  12   a . Note that the robot  100  is fixed to the floor by the fixing parts  12   b  in Embodiment 1. 
     Moreover, a base shaft  16  is fixed to an upper surface of the carriage  12 . The first arm  13 A and the second arm  13 B are provided to the base shaft  16  so as to be rotatable on a rotation axis L 1  passing through an axial center of the base shaft  16 . For example, the first arm  13 A and the second arm  13 B are provided with a height difference therebetween. The control device  11  is accommodated in the carriage  12 . Note that the first arm  13 A and the second arm  13 B are configured to be operatable independently or in a mutually associated manner. 
     The first arm  13 A includes an arm part  15 , a wrist part  17 , a first hand part  18 A, and an attaching part  20 . Similarly, the second arm  13 B includes an arm part  15 , a wrist part  17 , a second hand part  18 B, and an attaching part  20 . 
     The arm part  15  is comprised of a first link  15   a  and a second link  15   b , which are substantially rectangular parallelepiped, in Embodiment 1. The first link  15   a  is provided with a rotary joint J 1  at a base-end part, and a rotary joint J 2  at a tip-end part. The second link  15   b  is provided with a linear-motion joint J 3  at a tip-end part. 
     The first link  15   a  is coupled to the base shaft  16  via the rotary joint J 1  at the base-end part so that it is rotatable on the rotation axis L 1  by the rotary joint J 1 . The second link  15   b  is coupled to the tip-end part of the first link  15   a  via the rotary joint J 2  at the base-end part so that it is rotatable on a rotation axis L 2  by the rotary joint J 2 . 
     The wrist part  17  is coupled to the tip-end part of the second link  15   b  via the linear-motion joint J 3  so that it can ascend and descend with respect to the second link  15   b . A rotary joint J 4  is provided to a lower end part of the wrist part  17 , and the attaching part  20  is provided to a lower end part of the rotary joint J 4 . 
     The attaching part  20  is configured so that the first hand part  18 A or the second hand part  18 B is attachable thereto and detachable therefrom. For example, the attaching part  20  has a pair of bar members which are configured to be adjustable of the distance therebetween, and the pair of bar members can pinch the first hand part  18 A or the second hand part  18 B to attach the first hand part  18 A or the second hand part  18 B to the wrist part  17 . Thus, the first hand part  18 A or the second hand part  18 B is rotatable on a rotation axis L 3  by the rotary joint J 4 . Note that the bar member may be bent at a tip-end part. 
     Here, the first hand part  18 A of the first arm  13 A is described in detail with reference to  FIGS. 4 and 5 . 
       FIG. 4  is a schematic view illustrating an outline configuration of a left-side side surface of the first hand part of the robot illustrated in  FIG. 1 .  FIG. 5  is a cross-sectional view of the first holding part of the first hand part illustrated in  FIG. 4 , taken along a line A-A. Note that, in  FIG. 4 , the up-and-down directions and the front-and-rear directions of the robot are expressed as up-and-down directions and front-and-rear directions in the figure. Moreover, in  FIG. 5 , front-and-rear directions and left-and-right directions of the robot are expressed as front-and-rear directions and left-and-right directions in the figure. 
     As illustrated in  FIGS. 4 and 5 , the first hand part  18 A of the first arm  13 A is comprised of a fixing part  8 A, an intermediate part  9 A, and a first holding part  10 A, and the fixing part  8 A is connected with (fixed to) the first holding part  10 A via the intermediate part  9 A. Note that, in Embodiment 1, although the form in which the fixing part  8 A is, but not limited to be, connected with the first holding part  10 A via the intermediate part  9 A is adopted, the form in which the fixing part  8 A is directly connected to the first holding part  10 A may be adopted. 
     The fixing part  8 A is comprised of a first member  81  and a second member  82 . The first member  81  is a part which the attaching part  20  contacts, and is herein formed in a plate shape. The second member  82  is fixed to a lower surface of the first member  81 , and is formed in an inverted L-shape when seen horizontally. 
     The first holding part  10 A is comprised of a plate-shaped third member  103 , and a fourth member  104  and a fifth member  105  for connecting the third member  103  to the intermediate part  9 A. Note that the third member  103  may be formed in meshes by forming perforations in a principal surface in a lattice shape and may be formed in the principal surface with slits extending in the up-and-down directions or the front-and-rear directions. 
     The fourth member  104  is formed in an inverted L-shape when seen in the front-and-rear directions, and the fifth member  105  is formed in an L-shape when seen in the left-and-right directions. A lower surface of the fifth member  105  is connected (fixed) to an upper surface of the fourth member  104 . Moreover, the third member  103  is connected (fixed) to a right-side side surface of the fourth member  104 , and a normal direction of the principal surface of the third member  103  is oriented in left-and-right directions. 
     A notch (contact surface)  103   a  is formed in a lower part of the principal surface of the third member  103 . The notch  103   a  is formed conforming to the shape of an outer circumferential surface of the workpiece  202  when seen in the normal direction of the principal surface of the notch  103   a . The phrase “conforming to the shape of the outer circumferential surface of the workpiece  202 ” as used herein refers to the shape which can contact the outer circumferential surface of the workpiece  202 . 
     For example, in Embodiment 1, the notch  103   a  is formed in a substantially U-shape by cutting a lower end of the third member  103  in an arc shape (semicircle). That is, an inner circumferential surface of the notch  103   a  is formed in the arc shape (semicircle). Note that the inner circumferential surface of the notch  103   a  may have a polygonal shape, such as a rectangular shape or a trapezoid shape, or may have a shape having curves, such as a U-shape, an ellipse shape, and a parabola shape. Moreover, an elastic member, such as rubber, may be provided to the inner circumferential surface of the notch  103   a  in terms of increasing a frictional resistance with the workpiece  202 . 
     Moreover, in Embodiment 1, as illustrated in  FIG. 5 , the inner circumferential surface of the notch  103   a  may incline so that an opening part area is reduced as it goes from one end (here, left principal surface; inner surface) to the other end (here, right principal surface; outer surface). Thus, the contact area with the outer circumferential surface of the workpiece  202  can be increased. 
     Next, the second hand part  18 B of the second arm  13 B is described in detail with reference to  FIGS. 6 and 7 . 
       FIG. 6  is a schematic view illustrating an outline configuration of the right-side side surface of the second hand part of the robot illustrated in  FIG. 1 .  FIG. 7  is a front view of the second holding part of the second hand part illustrated in  FIG. 6 . Note that, in  FIG. 6 , the up-and-down directions and the front-and-rear directions in the robot are expressed as up-and-down directions and front-and-rear directions in the figure. Moreover, in  FIG. 7 , the up-and-down directions and the left-and-right directions of the robot are expressed as up-and-down directions and left-and-right directions in the figure. 
     As illustrated in  FIGS. 6 and 7 , the second hand part  18 B of the second arm  13 B is comprised of a fixing part  8 B, an intermediate part  9 B, and a second holding part  10 B, and the fixing part  8 B is connected with (fixed to) the second holding part  10 B via the intermediate part  9 B. Note that, in Embodiment 1, although the form in which the fixing part  8 B is, but not limited to be, connected with the second holding part  10 B via the intermediate part  9 B is adopted, a form in which the fixing part  8 B is directly connected to the second holding part  10 B may be adopted. 
     The fixing part  8 B is comprised of a first member  81  and a second member  82 . The first member  81  is a part where the attaching part  20  contacts, and is herein formed in a plate shape. The second member  82  is fixed to a lower surface of the first member  81 , and is formed in an inverted L-shape when seen horizontally. 
     The second holding part  10 B is comprised of a plate-shaped sixth member  106 , a seventh member  107  and an eighth member  108  for connecting the sixth member  106  to the intermediate part  9 B. Note that the sixth member  106  may be formed in meshes by forming perforations in a principal surface in a lattice shape and may be formed in the principal surface with slits extending in the up-and-down directions or the front-and-rear directions. 
     The seventh member  107  is formed in an inverted L-shape when seen in the front-and-rear directions, and the eighth member  108  is formed in an L-shape when seen in the left-and-right directions. A lower surface of the eighth member  108  is connected (fixed) to an upper surface of the seventh member  107 . Moreover, the sixth member  106  is connected (fixed) to a left-side side surface of the seventh member  107 , and a normal direction of the principal surface of the sixth member  106  is oriented in the left-and-right directions. 
     A lower end part (tip-end part) of the principal surface of the sixth member  106  is formed in an arc shape (semicircle) when seen in the normal direction of the principal surface, and is formed so as to be reduced in the thickness as it goes downward (tip-end side). 
     Moreover, a protrusion  106   a  is disposed at a lower part of one principal surface (here, right principal surface; inner surface) of the sixth member  106 . The protrusion  106   a  is formed so as to conform to the shape of the opening part (here, one opening part) of the workpiece  202  when seen in the normal direction of the principal surface of the sixth member  106 . Here, the phrase “formed conforming to the shape of the opening part of the workpiece  202 ” as used herein refers to that it can contact an inner circumferential surface of the opening part of the workpiece  202 . 
     In Embodiment 1, although the protrusion  106   a  is, but not limited to be, formed in a circular shape when seen in the normal direction of the principal surface of the sixth member  106 , it may be formed in an arc shape, a U-shape, or a polygonal shape. Moreover, the protrusion  106   a  may be formed so that the thickness is reduced as it goes downwardly. 
     Note that, in Embodiment 1, although the form in which the first arm  13 A and the second arm  13 B have, but not limited to have, substantially the same configuration except for the first hand part  19 A and the second hand part  19 B, a form in which the first arm  13 A and the second arm  13 B have different configurations of the arm part  15  and the wrist part  17  may be adopted. 
     Moreover, each of the joints J 1 -J 4  of the first arm  13 A and the second arm  13 B is provided with a drive motor as one example of an actuator (not illustrated) which relatively rotates or ascends and descends the two members connected via the joint, the drive motor may be a servo motor which is servo-controlled by the control device  11 , for example. Moreover, each of the joints J 1 -J 44  is provided with a rotation sensor (not illustrated) which detects the rotational position of the drive motor, and a current sensor (not illustrated) which detects the current which controls the rotation of the drive motor. The rotation sensor may be an encoder, for example. 
     As illustrated in  FIG. 3 , the control device  11  includes a processor  11   a , such as a CPU, a memory  11   b , such as a ROM and/or a RAM, and a servo controller  11   c . The control device  11  is a robot controller provided with a computer, such as a microcontroller, for example. 
     Note that the control device  11  may be comprised of a single control device  11  which carries out a centralized control, or may be comprised of a plurality of control devices  11  which collaboratively carry out a distributed control. Moreover, in Embodiment 1, although the memory  11   b  is, but not limited to be, disposed in the control device  11 , the memory  11   b  may be provided separately from the control device  11 . 
     The memory  11   b  stores information, such as a basic program as the robot controller, and various fixed data. The processor  11   a  controls various operations of the robot  100  by reading and executing software, such as the basic program, stored in the memory  11   b . That is, the processor  11   a  generates a control command for the robot  100 , and then outputs the command to the servo controller  11   c . The servo controller  11   c  controls driving of the servo motors corresponding to the joints J 1 -J 4  of each arm  13  of the robot  100  based on the control command generated by the processor  11   a.    
     Note that, in Embodiment 1, although the robot  100  is, but not limited to be, a horizontal articulated robot, the robot  100  may be a vertical articulated robot. Moreover, the configuration of the robot  100  described above is one example, but the configuration of the robot  100  is not limited to this and may be changed suitably according to the types of the work, the workspace, etc. which are carried out using the robot  100 . 
     [Operation and Effects of Robot] 
     Next, operation and effects of the robot  100  according to Embodiment 1 are described with reference to  FIGS. 1 to 11 . Note that, below, operation of taking out or extracting the workpieces  202  (correctly, the workpiece stacked body  202 A) accommodated in the box  201 , and placing them on the belt conveyor  205  is described. Moreover, the following operation is performed by the processor  11   a  of the control device  11  reading the program stored in the memory  11   b.    
       FIG. 8  is a flowchart illustrating one example of the operation of the robot according to Embodiment 1.  FIGS. 9 to 11  are schematic views illustrating states of the robot when the robot operates in accordance with the flowchart illustrated in  FIG. 8 . For example,  FIG. 9  is a perspective view illustrating a state where the first arm and the second arm which are located above the workpieces descend to contact the workpieces.  FIG. 10  is a perspective view illustrating a state where the first holding part of the first arm and the second holding part of the second arm grip the workpieces.  FIG. 11  is a perspective view illustrating a state where the first arm and the second arm ascend, while the first holding part and the second holding part are maintaining holding the workpieces. 
     First, as illustrated in  FIG. 2 , suppose that the box  201  where the workpieces  202  are accommodated is disposed in front of the robot  100 , and the belt conveyor  205  is disposed at the side of the robot  100 . In addition, suppose that an instructive information indicative of executing an operation to take out the workpiece  202  accommodated in the box  201  and place the workpiece  202  on the belt conveyor  205  is inputted into the control device  11  via an input device (not illustrated) by the operator. 
     Then, as illustrated in  FIG. 8 , the control device  11  acquires the image information which is imaged by the imaging device  204 , and then acquires the positional information of the workpieces  202  accommodated in the box  201  based on the acquired image information (Step S 101 ). 
     Next, based on the positional information of the workpieces  202  acquired at Step S 101 , the control device  11  operates the first arm  13 A and the second arm  13 B so that they are located above the workpieces  202  (Step S 102 ). 
     For example, the control device  11  operates the first arm  13 A so that the first holding part  10 A is located above an outer circumferential surface of the workpiece  202  located rightmost, among the workpiece stacked body  202 A (e.g., the workpiece stacked body  202 A located frontmost). Here, the control device  11  may operate the first arm  13 A so that the first holding part  10 A is located above an outer circumferential surface near the other opening part (bottom) of the workpiece  202 . 
     On the other hand, the control device  11  operates the second arm  13 B so that the second holding part  10 B is located above one opening part of the workpiece  202  located leftmost, among the workpiece stacked body  202 A (e.g., the workpiece stacked body  202 A located frontmost). 
     Next, the control device  11  operates (descends) the first arm  13 A so that the inner circumferential surface of the notch  103   a  of the first holding part  10 A contacts the outer circumferential surface of the workpiece  202  (Step S 103 ; see  FIGS. 9 and 10 ). 
     On the other hand, the control device  11  operates (descends) the second arm  13 B so that the inner surface of the second holding part  10 B contacts one opening part of the workpiece  202  (Step S 104 ; see  FIGS. 9 and 10 ). Here, the control device  11  may operate the second arm  13 B so that the principal surface of the protrusion  106   a  of the sixth member  106  of the second arm  13 B slides on one opening part end of the workpiece  202 . 
     Note that, after execution of the operation (processing) of Step S 103 , the control device  11  may execute the operation (processing) of Step S 104 , or may simultaneously execute the operations of Steps S 103  and S 104 . Alternatively, the control device  11  may execute the operation of Step S 103  after execution of the operation of Step S 104 . 
     Next, the control device  11  operates at least one of the arms (the first arm  13 A or the second arm  13 B) so that the first holding part  10 A and the second holding part  10 B approach each other (Step S 105 ). 
     Thus, when the first holding part  10 A presses one opening part of the workpiece  202  to the other opening part (here, right side), the pressing force is received by the inner surface of the second holding part  10 B, thereby increasing the frictional resistance between the inner surface of the second holding part  10 B and the outer circumferential surface of the workpiece  202 . Moreover, when the second holding part  10 B presses the other opening part of the workpiece  202  to one opening part (here, left side), the pressing force is received by an inner circumferential surface of the first holding part  10 A. 
     Thus, since the workpieces  202  (correctly, the workpiece stacked body  202 A) are fully pinched by the first holding part  10 A and the second holding part  10 B, the workpieces  202  are fixed between the first holding part  10 A and the second holding part  10 B. Therefore, the robot  100  can move the workpieces  202  (workpiece stacked body  202 A) upwardly by the first holding part  10 A and the second holding part  10 B. 
     Note that, when pinching the workpieces  202  (workpiece stacked body  202 A) by the first holding part  10 A and the second holding part  10 B during the operation of Step S 105 , the control device  11  may operate the second arm  13 B so that an upper end face of the protrusion  106   a  of the sixth member  106  of the second holding part  10 B contacts an upper side part of the inner circumferential surface of the workpiece  202 . 
     Next, the control device  11  operates the first arm  13 A and the second arm  13 B to be located upward, while the arms are holding the workpieces  202  (workpiece stacked body  202 A) (Step S 106 ; see  FIG. 11 ). That is, the control device  11  operates the first arm  13 A and the second arm  13 B to move the workpieces  202  (workpiece stacked body  202 A) upward so that the workpieces  202  are taken out from the box  201 . 
     Next, the control device  11  operates the first arm  13 A and the second arm  13 B to place the workpieces  202  (workpiece stacked body  202 A) on the belt conveyor  205  (Step S 107 ), and then ends this program. 
     For example, the control device  11  rotates the first arm  13 A and the second arm  13 B so that the workpiece  202  are located above the belt conveyor  205 , and then moves the first arm  13 A and the second arm  13 B downwardly to place the workpiece  202  on the belt conveyor  205 . Then, the control device  11  operates the first arm  13 A or the second arm  13 B so that the first holding part  10 A and the second holding part  10 B separate from each other to release the holding state of the workpiece  202 , and then ends this program. 
     Note that the control device  11  may operate the first arm  13 A and the second arm  13 B to be located at a given preset position (initial position), and then end this program. Alternatively, the control device  11  repeats this program, and when all the workpieces  202  accommodated in the box  201  have been conveyed, it may output information (e.g., an image, sound, light, etc.) indicative of the completion of the conveyance. 
     Since the robot  100  according to Embodiment 1 configured in this way includes the first holding part  10 A having the notch  103   a  corresponding to the shape of the outer circumferential surface of the workpiece  202 , and the plate-shaped second holding part  10 B, it can easily hold and move the workpiece  202  having the cylindrical shape. 
     Moreover, in the robot  100  according to Embodiment 1, since the inner circumferential surface of the notch  103   a  of the first holding part  10 A is formed in the tapered shape, it can fully contact the outer circumferential surface of the workpiece  202 . Thus, the frictional resistance between the inner circumferential surface of the notch  103   a  and the outer circumferential surface of the workpiece  202  can be increased, and thereby the workpieces  202  can fully be held. 
     Moreover, in the robot  100  according to Embodiment 1, since the tip-end part of the sixth member  106  of the second holding part  10 B is formed in the tapered shape, the tip-end part of the second holding part  10 B can easily enter into the gap between an inner circumferential surface of the box  201  and one opening part of the workpiece  202 , when taking out the workpieces  202  accommodated in the box  201 . Thus, it can be prevented that, for example, the second holding part  10 B crushes the outer circumferential surface of the workpiece  202  to prevent the deformation of the workpiece  202 , thereby preventing the occurrence of poor appearance of the workpiece  202 . 
     Moreover, when causing the principal surface of the second holding part  10 B to contact one opening part of the workpiece  202 , it can be prevented that the second holding part  10 B crushes the outer circumferential surface of the workpiece  202  to prevent the deformation of the workpiece  202 , thereby preventing the occurrence of poor appearance of the workpiece  202 . 
     Moreover, in the robot  100  according to Embodiment 1, the protrusion  106   a  is formed in the principal surface of the sixth member  106  of the second holding part  10 B. Thus, when moving the workpiece  202  upwardly, it can further be prevented that the workpiece  202  drops downwardly by the inner circumferential surface of the workpiece  202  contacting the upper end face of the protrusion  106   a.    
     Moreover, in the robot  100  according to Embodiment 1, since the protrusion  106   a  of the second holding part  10 B is formed in the tapered shape so that the thickness is reduced as it goes downwardly, it is prevented that the protrusion  106   a  crushes the outer circumferential surface of the workpiece  202 , when causing the principal surface of the protrusion  106   a  to contact one opening part of the workpiece  202 . Thus, the deformation of the workpiece  202  can be prevented and the occurrence of poor appearance of the workpiece  202  can be prevented. 
     Further, in the robot  100  according to Embodiment 1, the protrusion  106   a  of the second holding part  10 B is formed so as to conform to the shape of one opening part of the workpiece  202 . Thus, the outer circumferential surface of the protrusion  106   a  can fully contact the inner circumferential surface of the one opening part of the workpiece  202 , and thereby the workpiece  202  can fully be held. 
     Note that although in Embodiment 1 the operation of the robot  100  which takes out the workpiece stacked body  202 A accommodated in the box  201  and places it on the belt conveyor  205 , is illustrated, but without being limited to this configuration, an operation in which the robot  100  holds one workpiece  202  put over sideways on a floor surface and conveys it may be performed. 
     [Modification 1] 
     Next, a modification of the robot  100  according to Embodiment 1 is described. 
     In the robot of Modification 1 in Embodiment 1, the first holding part is comprised of a bar-like member. Below, one example of the robot of Modification 1 is described with reference to  FIG. 12 . 
       FIG. 12  is a schematic view illustrating an outline configuration of a first hand part of the robot of Modification 1 in Embodiment 1. Note that, in  FIG. 12 , the up-and-down directions and the front-and-rear directions in the robot are expressed as up-and-down directions and front-and-rear directions in the figure. 
     As illustrated in  FIG. 12 , the robot  100  of Modification 1 has the same fundamental configuration as the robot  100  according to Embodiment 1, but the configuration of the third member  103  of the first holding part  10 A differs. For example, the third member  103  has a first bar member  103 A and a second bar member  103 B, and the first bar member  103 A is bent (curved) so as to conform to the shape of the outer circumferential surface of the workpiece  202 . Moreover, the second bar member  103 B connects the first bar member  103 A with the fourth member  104 . Note that the first bar member  103 A may be directly connected to the fourth member  104 . 
     Moreover, an inner circumferential surface  103   b  of the first bar member  103 A constitutes the contact surface. Similar to the notch  103   a  of Embodiment 1, the inner circumferential surface  103   b  may incline as it goes from one end to the other end. 
     Even with the robot  100  of Modification 1 configured in this way, similar operation and effects as the robot  100  according to Embodiment 1 can be obtained. 
     [Modification 2] 
     In a robot of Modification 2 in Embodiment 1, a second holding part is comprised of a bar-like member. Below, one example of the robot of Modification 2 is described with reference to  FIG. 13 . 
       FIG. 13  is a schematic view illustrating an outline configuration of the second hand part of the robot of Modification 2 in Embodiment 1. Note that, in  FIG. 13 , the up-and-down directions and the front-and-rear directions in the robot are expressed as up-and-down directions and front-and-rear directions in the figure. 
     As illustrated in  FIG. 13 , the robot  100  of Modification 2 has the same fundamental configuration as the robot  100  according to Embodiment 1, but it differs in that the sixth member  106  of the second holding part  10 B is formed in a bar shape. Note that, in Modification 2, the form in which the sixth member  106  is comprised of a single bar member is adopted, but without being limited to this configuration, a form in which the sixth member  106  is comprised of a plurality of bar members may be adopted. 
     Even with the robot  100  of Modification 2 configured in this way, similar operation and effects as the robot  100  according to Embodiment 1 can be obtained. 
     It is apparent for a person skilled in the art that many improvements or other embodiments of the present disclosure are possible from the above description. Therefore, the above description is to be interpreted only as illustration, and it is provided in order to teach a person skilled in the art the best mode that implements the present disclosure. The details of the structures and/or the functions may substantially be changed without departing from the spirit of the present disclosure. 
     INDUSTRIAL APPLICABILITY 
     Since the robot and the method of operating the same of the present disclosure can easily hold and move the object having the cylindrical shape, they are useful in industrial robot fields. 
     DESCRIPTION OF REFERENCE CHARACTERS 
     
         
         J 1  Rotary Joint 
         J 2  Rotary Joint 
         J 3  Linear-motion Joint 
         J 4  Rotary Joint 
         L 1  Rotation Axis 
         L 2  Rotation Axis 
         L 3  Rotation Axis 
           8 A Fixing Part 
           8 B Fixing Part 
           9 A Intermediate Part 
           9 B Intermediate Part 
           10 A First Holding Part 
           10 B Second Holding Part 
           11  Control Device 
           11   a  Processor 
           11   b  Memory 
           11   c  Servo Controller 
           12  Carriage 
           12   a  Wheel 
           12   b  Fixing Part 
           13 A First Arm 
           13 B Second Arm 
           15  Arm Part 
           15   a  First Link 
           15   b  Second Link 
           16  Base Shaft 
           17  Wrist Part 
           18 A First Hand Part 
           18 B Second Hand Part 
           20  Attaching Part 
           81  First Member 
           82  Second Member 
           100  Robot 
           101  First Member 
           102  Second Member 
           103  Third Member 
           103   a  Notch 
           104  Fourth Member 
           105  Fifth Member 
           106  Sixth Member 
           106   a  Protrusion 
           107  Seventh Member 
           108  Eighth Member 
           201  Box 
           202  Workpiece 
           202 A Workpiece Stacked Body 
           203  Pedestal 
           203 A Support Member 
           204  Imaging Device 
           205  Belt Conveyor