Patent Publication Number: US-2022219336-A1

Title: Holding device and conveying system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-004553, filed Jan. 14, 2021; the entire contents of (all of) which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a holding device and a conveying system. 
     BACKGROUND 
     Conventionally, a picking robot having a robot hand having a plurality of holding units for holding an article is known. This type of picking robot can handle a variety of articles by properly using a plurality of holding units. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a picking robot according to an embodiment. 
         FIG. 2  is a side view of a robot hand of the embodiment. 
         FIG. 3  is a front view of the robot hand of the embodiment. 
         FIG. 4  is a perspective view showing positions of a plurality of motors in the robot hand. 
         FIG. 5  is a perspective view showing an interrelationship of gears constituting a plurality of rotational drive mechanisms. 
         FIG. 6  is a front view of a base plate. 
         FIG. 7  is a front view of a holding unit. 
         FIG. 8  is a front view of a suction unit. 
         FIG. 9  is a diagram showing an arrangement of negative pressure supply pipes. 
         FIG. 10  is a diagram showing an arrangement of relay pipes. 
         FIG. 11  is a diagram showing an operation of the robot hand when switching units. 
         FIG. 12  is a diagram showing the operation of the robot hand when an orientation of the holding unit is changed. 
         FIG. 13  is a diagram showing the operation of the robot hand when the orientation of the suction unit is changed. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a holding device of an embodiment includes: a support member; a first holding unit configured to be rotatably supported by the support member and have a first holding portion configured to hold a holding object; a second holding unit configured to be rotatably supported by the support member independently of the first holding unit and have a second holding portion configured to hold the holding object; and a controller configured to control an operation of the first holding unit and the second holding unit. The controller is configured to switch which of the first holding unit and the second holding unit is used for holding the holding object, by rotating the first holding unit and the second holding unit in a state where the first holding unit and the second holding unit face different directions, and control to change an orientation with respect to the support member, by rotating at least one of the first holding unit and the second holding unit with respect to the support member. 
     Hereinafter, the holding device and the conveying system of an embodiment will be described with reference to the drawings. 
     The XYZ Cartesian coordinate system is used in the description of the holding device and the transporting device of the embodiment. The Z-axis direction corresponds to the vertical direction, the +Z direction is defined as upward, and the −Z direction is defined as downward. The X-axis direction and the Y-axis direction are orthogonal to each other in a horizontal plane. In the horizontal plane, the direction in which the holding claw of the holding unit, which will be described later, opens and closes is defined as the X-axis direction. In the horizontal plane, the direction orthogonal to the opening/closing direction of the holding claw is defined as the Y-axis direction. 
       FIG. 1  is a schematic diagram showing a schematic configuration of the picking robot  10  of the present embodiment. 
     As shown in  FIG. 1 , the picking robot  10  includes a robot hand  11 , an arm  12 , and a controller  13 . The robot hand  11  holds a holding object P that is a target of transportation. The arm  12  moves the robot hand  11  to a predetermined position. The controller  13  controls the robot hand  11  and the arm  12 . More specifically, the controller  13  of the picking robot  10  controls the entire system. The controller includes a planning controller that plans the actions of the arm  12  and the robot hand  11 , and an image processing controller that performs recognition processing such as camera information. The configuration of the robot hand  11  will be described in detail later. 
     The picking robot  10  of the present embodiment corresponds to a conveying system within the scope of claims. The robot hand  11  of the present embodiment corresponds to a holding device within the scope of claims. 
     The outline of the configuration and operation of the picking robot  10  will be described below. 
     The picking robot  10  is used, for example, as a picking robot for physical distribution. The picking robot  10  holds various holding objects P placed in various situations in the transport source S 1  and moves them to the transport destination S 2 . The use of the picking robot  10  is not limited to logistics, but can be widely applied to industrial use, other uses, and the like. The picking robot  10  of the present embodiment is not limited to a device whose main purpose is to transport the holding object P, and also includes a device that transports or moves an article as a part of another purpose such as assembling a product. 
     The transport source S 1  is, for example, various conveyors, pallets, containers, and the like, but is not limited thereto. A plurality of types of holding objects P having different dimensions and weights are placed at random positions in an arbitrary orientation on the transport source S 1 . In the present embodiment, the dimensions of the holding object P that is a target of transportation vary from, for example, about several cm square to about several tens of cm square. The weight of the holding object P varies from, for example, about several tens of g to about several kg. The dimensions and weight of the holding object P are not limited to the above examples. 
     The transport destination S 2  is, for example, various conveyors, pallets, containers, or the like, as in the transport source S 1 , but is not limited thereto. The container of the transport source S 1  and the transport destination S 2  broadly means a member capable of accommodating the holding object P, for example, a box-shaped member. 
     The arm  12  is composed of, for example, 6-axis vertical articulated arm. The arm  12  includes a plurality of arm members  15  and a plurality of joint portions  16 . The joint portion  16  rotatably connects the arm members  15  connected to the joint portion  16 . The arm  12  may be composed of, for example, 4-axis vertical articulated arm or 3-axis orthogonal arm. The arm  12  may be a mechanism for moving the robot hand  11  to a desired position by a configuration other than the vertical articulated arm and the orthogonal arm. Although not shown, the arm  12  includes a sensor or the like that detects the angle formed by the arm member  15  at each joint portion  16 . 
     Although not shown, the picking robot  10  further includes sensors installed in the vicinity of the transport source S 1  and the transport destination S 2 . The sensor is composed of, for example, an RGB-D sensor, a camera, a contact sensor, a distance sensor, and the like. The sensor acquires, for example, information about the holding object P placed in the transport source S 1 , information about the status of the transport source S 1  or the transport destination S 2 , and the like. 
     The controller  13  manages and controls each unit of the picking robot  10 . The controller  13  acquires various information detected by the sensor and controls the position and operation of the robot hand  11  based on the acquired information. The controller  13  is composed of a microcomputer including a processor such as a CPU (Central Processing Unit). The controller  13  is realized by a processor such as a CPU executing a program stored in a memory or an auxiliary storage device. At least a part of the controller  13  may be realized by hardware such as LSI (LargeScale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or may be realized by collaboration between software and hardware. As described above, the controller  13  has an image processing controller that processes the recognition result and the like, and a recognition system device such as a camera is linked under the image processing controller. Further, the planning controller is composed of a controller that controls the arm  12  and a controller that controls the robot hand  11 . 
     Hereinafter, the robot hand  11  will be described. 
       FIG. 2  is a side view of the robot hand  11  as viewed from the +X direction.  FIG. 3  is a front view of the robot hand  11  as viewed from the +Y direction. In the present specification, a view of each device viewed from the +X direction is referred to as a side view, and a view of each device viewed from the +Y direction is referred to as a front view. 
     As shown in  FIG. 2 , the robot hand  11  has a base plate  20 , a holding unit  21 , and a suction unit  22 . Further, here, the robot hand  11  includes a first rotation drive mechanism  23 , a second rotation drive mechanism  24 , a third rotation drive mechanism  25 , and a fourth rotation drive mechanism  26 , which are shown in  FIGS. 3 to 5  described later. The rotation drive mechanisms  23 ,  24 ,  25 , and  26  will be described in detail later with reference to other drawings such as  FIGS. 3 to 5 . 
     The base plate  20  of this embodiment corresponds to a support member within the scope of claims. The holding unit  21  of the present embodiment corresponds to a first holding unit within the scope of claims. The suction unit  22  of the present embodiment corresponds to a second holding unit within the scope of claims. 
     The base plate  20  is made of a plate-shaped member. The base plate  20  has a first surface  20   a  and a second surface  20   b  opposite to the first surface  20   a . The base plate  20  supports the holding unit  21  and the suction unit  22 . The holding unit  21  and the suction unit  22  face the first surface  20   a  of the base plate  20  and are arranged side by side in the Y-axis direction. The base plate  20  is arranged only on one side of the holding unit  21  and the suction unit  22 , and is not arranged on the other side. That is, the holding unit  21  and the suction unit  22  are not sandwiched by the base plate  20  from both sides, but are supported by a cantilever structure with respect to the base plate  20 . 
     The suction unit  22  is arranged so as to face the first surface  20   a  of the base plate  20 . The holding unit  21  is arranged on the side opposite to the side where the base plate  20  is located with respect to the suction unit  22 . That is, these two units  21  and  22  are arranged in the order of the suction unit  22  and the holding unit  21  from the first surface  20   a  side of the base plate  20 . At least a part of the base plate  20 , at least a part of the suction unit  22 , and at least a part of the holding unit  21 , which intersect with the first surface  20   a  when viewed from the normal direction (Y-axis direction) of the first surface  20   a , are placed so that they overlap each other. In the following description, the direction in which the base plate  20 , the suction unit  22 , and the holding unit  21  overlap (Y-axis direction) is referred to as the thickness direction of the robot hand  11 . 
     The holding unit  21  has a holding portion  28 , and holds the holding object P from the side by using a holding claw  29  (holding part) described later. The holding unit  21  is rotatably supported in a plane (in the XZ plane) parallel to the first surface  20   a  with respect to the base plate  20 . 
     The holding portion  28  of the present embodiment corresponds to the first holding portion within the scope of the claims. 
     The suction unit  22  has a suction portion  31 , and holds the holding object Pin a form of negative pressure suction by using a suction pad  32  described later. The suction unit  22  is rotatably supported in a plane (in the XZ plane) parallel to the first surface  20   a  with respect to the base plate  20 . 
     The suction portion  31  of the present embodiment corresponds to a second holding unit within the scope of the claims. 
     As shown in  FIG. 2 , an ejector  48  and a piping guide  49  are arranged on the second surface  20   b  of the base plate  20 . The ejector  48  uses compressed air to generate a negative pressure that acts as a suction force for the suction pad  32 . The piping guide  49  guides the position of the negative pressure supply piping  50 , which will be described later, on one surface  44   a  of the base plate cover  44 . In  FIG. 2 , the negative pressure supply pipe  50  is not shown. 
     Hereinafter, the outline of the rotation drive mechanism included in the robot hand  11  will be described. 
     The robot hand  11  has a function of switching which of the holding unit  21  and the suction unit  22  to be used for holding the holding object P according to the holding object P, a function of changing the orientation of the holding unit  21 , a function of changing the orientation of the suction portion  31 , and a function of opening and closing the holding claw  29 . In order to realize these functions, the robot hand  11  includes, as the rotation drive mechanism, a first rotation drive mechanism  23 , a second rotation drive mechanism  24 , a third rotation drive mechanism  25 , a fourth rotation drive mechanism  26 , and the like. 
     The first rotation drive mechanism  23  shown in  FIGS. 3 and 4  is used both when switching between the holding unit  21  and the suction unit  22  to be used, and when changing the orientation of the holding unit  21 . The second rotation drive mechanism  24  shown in  FIG. 4  is used to correct the orientation change of the suction unit  22  due to the orientation change of the holding unit  21 . The third rotation drive mechanism  25  shown in  FIG. 4  is used when changing the orientation of the suction portion  31 . The fourth rotation drive mechanism  26  is used when opening and closing the holding claw  29  constituting the holding portion  28 . 
     Hereinafter, in order to make the explanation easier to understand, the first rotation drive mechanism  23  is referred to as a unit switching and holding orientation change mechanism  23 , the second rotation drive mechanism  24  is referred to as a suction unit orientation correction mechanism  24 , the third rotation drive mechanism  25  is referred to as a suction orientation changing mechanism  25 , and the fourth rotation drive mechanism  26  is referred to as a holding claw opening/closing mechanism  26 . 
     The installation positions of the motors constituting each rotary drive mechanism will be described first. 
       FIG. 4  is a perspective view showing the positions of the plurality of motors. 
     As shown in  FIG. 4 , the first motor  35  constituting the unit switching/holding orientation changing mechanism  23  is installed on the base plate  20 . The second motor  36  constituting the suction unit orientation correction mechanism  24  is installed in the holding unit  21 . The third motor  37  constituting the suction orientation changing mechanism  25  is installed in the suction unit  22 . The fourth motor  38  constituting the holding claw opening/closing mechanism  26  is installed in the holding unit  21 . Each of the first motor  35 , the second motor  36 , the third motor  37 , and the fourth motor  38  is composed of, for example, a servomotor. 
       FIG. 6  is a front view showing the configuration of the base plate  20 . 
     As shown in  FIGS. 3 and 6 , the second surface  20   b  of the base plate  20  has the first motor  35 , the first shaft  41 , the first gear  42 , and the components of the unit switching/holding orientation changing mechanism  23 . The second gear  43  is arranged. The first shaft  41  is connected to the first motor  35 . The first shaft  41  extends downward (in the Z-axis direction) of the first motor  35 . The first gear  42  is connected to the lower end of the first shaft  41 . The first gear  42  is rotatable about the axis of the first shaft  41 . The second gear  43  is arranged so as to mesh with the first gear  42 . The second gear  43  converts the rotation of the first gear  42 , which rotates about the Z axis, into the rotation about the Y axis. In the case of the present embodiment, the first gear  42  and the second gear  43  are composed of helical gears, but the type of gear is not particularly limited. The first shaft  41 , the first gear  42 , and the second gear  43  are covered with a base plate cover  44  (see  FIG. 2 ). 
       FIG. 5  is a perspective view showing the interrelationship of various gears constituting the plurality of rotational drive mechanisms. In  FIG. 5 , in order to make it easier to see the positional relationship of the plurality of gears, the illustration of members other than the gears is omitted as appropriate. 
     As shown in  FIG. 5 , the second gear  43  is connected to the second shaft  46  fixed to the holding unit  21 . As a result, when the first motor  35  rotates, the holding unit  21  rotates in the XZ plane via the first shaft  41 , the first gear  42 , the second gear  43 , and the second shaft  46 . Further, the axis of the second shaft  46  is the first rotation axis AX 1  when the holding unit  21  and the suction unit  22  rotate integrally at the time of unit switching, and is the second rotation axis AX 2  when the holding unit  21  changes its orientation. That is, the first rotation axis AX 1  when the holding unit  21  and the suction unit  22  are switched and the second rotation axis AX 2  when the orientation of the holding unit  21  is changed are arranged on a common axis. 
     As shown in  FIG. 6 , a top plate  52  is provided on the upper portion of the base plate  20 . A force sensor  53  is arranged on the upper surface of the top plate  52 . The force sensor  53  detects the force received by each of the units  21  and  22  when the holding unit  21  or the suction unit  22  comes into contact with an arbitrary object. The detected value of the force sensor  53  is output to the controller  13  and used for controlling each part of the holding unit  21  or the suction unit  22 . 
     On the first surface  20   a  of the base plate  20 , the bearing  55  is arranged at a position corresponding to the second gear  43  arranged on the second surface  20   b . The bearing  55  smoothly rotates the suction unit  22  with respect to the base plate  20 . 
       FIG. 7  is a front view showing the configuration of the holding unit  21 . 
     As shown in  FIG. 7 , the holding unit  21  includes a holding unit base material  57 , a holding portion  28 , a holding claw opening/closing mechanism  26 , and a second motor  36 . The holding portion  28  includes a link portion  58  and a plurality of holding claws  29 . The holding unit  21  holds the holding object P in a state of being held by the plurality of holding claws  29 . The second motor  36  is a component of the suction unit orientation correction mechanism  24 . 
     The holding unit base material  57  supports each member such as the link portion  58 , the holding claw opening/closing mechanism  26 , and the second motor  36 . The holding portion  28  of the present embodiment includes two holding claws  29  connected to the link portion  58 . The holding portion  28  may include three or more holding claws, and the number of holding claws is not particularly limited. 
     The link portion  58  is composed of two parallel links  59 . Each of the two holding claws  29  is connected to each of the two parallel links  59 . Due to the movement of the link portion  58 , the two holding claws  29  open and close by moving in the direction that increase the distance from each other in the X-axis direction while rising in the +Z direction and moving in the direction that narrows the distance from each other in the X-axis direction while descending in the −Z direction. 
     The holding claw opening/closing mechanism  26  includes a fourth motor  38 , a third gear  61 , a fourth gear  62 , and a fifth gear  63 . The third gear  61  is connected to the fourth motor  38 . The fourth gear  62  meshes with the third gear  61 . The fifth gear  63  meshes with the fourth gear  62 . When the third gear  61  is rotated by the drive of the fourth motor  38 , the fourth gear  62  and the fifth gear  63  rotate in opposite directions in the XZ plane. The two holding claws  29  perform either an opening operation or a closing operation depending on which direction the fourth gear  62  and the fifth gear  63  rotate. The holding claw opening/closing mechanism  26  is covered with a holding unit cover  64  (see  FIG. 2 ). 
     A displacement sensor  65  is arranged above the holding claw  29 . The displacement sensor  65  detects the force received by the holding claw  29  when the holding claw  29  comes into contact with an arbitrary object. The detected value of the holding claw  29  is output to the controller  13  and used for controlling the holding unit  21 . In this way, in addition to the configuration in which the value of the displacement sensor  65  is directly read into the controller  13 , a configuration in which a controller dedicated to hand control monitors the value of the displacement sensor  65  and determines contact with the item may be adopted. 
     The second motor  36  is arranged on the holding unit base material  57  in the −X direction with respect to the fourth motor  38 . As shown in  FIG. 5 , the sixth gear  66  is arranged in the +Y direction with respect to the second motor  36 . The sixth gear  66  is connected to the second motor  36 . The sixth gear  66  meshes with the seventh gear  67 , which will be described later, of the suction unit  22 . The sixth gear  66  constitutes the suction unit orientation correction mechanism  24  together with the second motor  36 . 
       FIG. 8  is a front view showing the configuration of the suction unit  22 . 
     As shown in  FIG. 8 , the suction unit  22  includes a suction link portion  69 , a suction portion  31 , a suction orientation changing mechanism  25 , and a seventh gear  67 . The suction portion  31  includes a base  71  and a plurality of suction pads  32 . The suction unit  22  holds the holding object P in a state of negative pressure suction by a plurality of suction pads  32 . 
     The suction link portion  69  has a first surface  69   a  and a second surface  69   b  opposite to the first surface  69   a . The second surface  69   b  of the suction link portion  69  faces the first surface  20   a  of the base plate  20 . The suction link portion  69  has an opening  69   h . The opening  69   h  is provided with a number of pipe joints  73  corresponding to the number of suction pads  32 . The pipe joint  73  communicates with the negative pressure supply pipe  50 , which will be described later. A relay pipe  74  is arranged in the space between the plurality of pipe joints  73  and the suction portion  31 . A plurality of inlets  79 , which will be described later, are provided on the second surface  69   b  of the suction link portion  69 . A negative pressure flow path (not shown) is formed inside the suction link portion  69  to communicate the pipe joint  73  and the inlet  79 . 
     The suction portion  31  includes four suction pads  32  arranged on a rectangular base  71 . The suction pad  32  comes into contact with one surface of the holding object P and sucks the holding object P by a negative pressure. The four suction pads  32  are arranged in the vicinity of the four corners of the base  71 . Therefore, the four suction pads  32  are arranged in a rectangular shape. The number of suction pads  32  does not have to be four, and is not particularly limited. The arrangement of the suction pads  32  does not have to be rectangular and is not particularly limited. 
     The suction orientation changing mechanism  25  has a fourth motor  38  arranged on the suction link portion  69 . The suction portion  31  rotates in the XZ surface with respect to the suction link portion  69  as the fourth motor  38  rotates. The rotation axis of the fourth motor  38  is the third rotation axis AX 3  when the orientation of the suction portion  31  is changed. 
     A seventh gear  67  is fixed to the first surface  69   a  of the suction link portion  69 . The seventh gear  67  is arranged at the end of the first surface  69   a  of the suction link portion  69  on the side opposite to the side where the suction portion  31  is provided (in the −Z direction). As described above, the seventh gear  67  meshes with the sixth gear  66  connected to the 2nd motor  36  on the holding unit  21  to form the suction unit orientation correction mechanism  24 . 
     As shown in  FIG. 5 , a second shaft  46  fixed to the holding unit  21  is inserted inside the seventh gear  67 . A bearing  55  (see  FIG. 6 ) is arranged between the second shaft  46  and the suction unit  22 . 
     As shown in  FIG. 2 , the base plate  20 , the suction unit  22 , and the holding unit  21  overlap each other in the thickness direction of the robot hand  11 . Therefore, the position of the suction link portion  69  and the position of the holding unit base material  57  in the thickness direction (Y-axis direction) of the robot hand  11  are different from each other. That is, the suction link portion  69  is located in the +Y direction with respect to the holding unit base material  57 . Further, the suction portion  31  is arranged in the −Y direction with respect to the suction link portion  69 . 
     With the above configuration, the first holding of the holding unit  21  is in a state where the holding portion  28  and the suction portion  31  are oriented 180° differently from each other in the plane parallel to the first surface  20   a  of the base plate  20  (in the XZ plane). The center line H 1  and the second holding center line H 2  of the suction unit  22  are arranged on the same straight line parallel to the Z-axis direction. The first holding center line H 1  is defined as a straight line parallel to the Z axis, and a straight line passing through the center of the two holding claws  29  of the holding unit  21  in the opening/closing direction (X-axis direction) and the center of one holding claw  29  in the width direction (Y-axis direction). The second holding center line H 2  is defined as a straight line parallel to the Z-axis and passing through the center of a rectangle in which the four suction pads  32  of the suction unit  22  viewed from the Z-axis direction are arranged. Hereinafter, the distance between the tip of the holding claw  29  and the suction surface of the suction pad  32  when the holding portion  28  and the suction portion  31  face different directions by 180° is defined as the length L of the robot hand  11 . 
     Hereinafter, a route for supplying a negative pressure to the suction pad  32  will be described. 
       FIG. 9  is a diagram showing the arrangement of the negative pressure supply pipe  50 . 
     As shown in  FIG. 9 , a plurality of compressed air introduction pipes  76  and a plurality of negative pressure supply pipes  50  are connected to the ejector  48 . The compressed air introduction pipe  76  is arranged along the arm member  15  and the joint portion  16 , and is branched into a plurality of pipes in a state where the position is regulated by the guide roller  77 , and each of them is connected to the ejector  48 . The number of the compressed air introduction pipes  76  and the negative pressure supply pipes  50  corresponds to the number of the suction pads  32 . In the case of this embodiment, the number of the compressed air introduction pipes  76  and the number of the negative pressure supply pipes  50  are both four. 
     The plurality of negative pressure supply pipes  50  extend downward (−Z direction) along one surface  44   a  of the base plate cover  44  by the piping guide  49 , and are curved and extend upward (+Z direction). The lower end of the curved portion of the plurality of negative pressure supply pipes  50  is arranged at a position equivalent to the lower end of the base plate cover  44  or a position higher than the lower end of the base plate cover  44 . The compressed air introduction pipe  76  and the negative pressure supply pipe  50  are composed of, for example, a spirally wound resin spiral tube. As a result, the compressed air introduction pipe  76  and the negative pressure supply pipe  50  can be expanded and contracted according to the operation of each part. The compressed air introduction pipe  76  and the negative pressure supply pipe  50  may be composed of tubes of other forms. 
     As shown in  FIG. 6 , in the lower part of the base plate  20 , a cutout portion  20   k  having a rectangular cutout at a corner is formed on a side opposite to the side where the first gear  42  is provided in the X-axis direction. Therefore, the width of the lower part of the base plate  20  is narrower than the width of the upper part of the base plate  20 . On the other hand, as shown in  FIG. 8 , the suction link portion  69  is formed to have the same width in the vertical direction. As a result, as shown in  FIG. 9 , a part of the suction link portion  69  is exposed from the base plate  20  in a state where the suction unit  22  and the base plate  20  are overlapped when viewed from the +Y direction. A plurality of inlets  79  are provided in a region of the suction link portion  69  that is exposed to the outside from the cutout portion  20   k  of the base plate  20 . The negative pressure supply pipe  50  is connected to the inlet  79 . 
       FIG. 9  shows a state in which the holding unit  21  is used and the suction unit  22  is not used, and the suction unit  22  is in an orientation in which the suction portion  31  faces upward (+Z side) in the vertical direction. In this orientation, the negative pressure supply pipe  50  is wound counterclockwise from the pipe guide  49  side toward the inlet  79  side and is connected to the inlet  79 . Therefore, it is necessary to rotate the suction unit  22  clockwise when the unit is switched. As a result, the negative pressure supply pipe  50  can be deformed without any problem from the bent state to the extended state. That is, the negative pressure supply pipe  50  is arranged so as to wind from the inlet  79  side to the suction pad  32  side in the direction opposite to the direction in which the suction unit  22  rotates. 
     In the above configuration, the compressed air introduced from the compressed air introduction pipe  76  is converted into negative pressure air by the ejector  48 . The negative pressure air is supplied to the inlet  79  via the negative pressure supply pipe  50 , and is supplied to the pipe joint  73  via the negative pressure flow path formed inside the suction link portion  69 . 
     Although not shown in  FIG. 9 , in addition to the negative pressure supply pipe  50 , the electrical wiring for transmitting signals to each motor is also routed on the second surface  20   b  side of the base plate  20  as in the negative pressure supply pipe  50 . 
       FIG. 10  is a schematic diagram explaining the arrangement of the relay pipe  74 . In  FIG. 10 , only the relay pipe  74 , the suction pad  32 , and the pipe joint  73  are shown in order to make it easier to see the arrangement of the relay pipe  74 . 
     As shown in  FIG. 10 , a plurality of relay pipes  74  are provided in the space between the plurality of suction pads  32  and the plurality of pipe joints  73 . The relay pipe  74  connects the suction pad  32  and the pipe joint  73 . The relay pipe  74  transports the negative pressure air supplied from the negative pressure flow path of the suction link portion  69  to the suction pad  32 . The relay pipe  74  is spirally arranged in the space between the suction pad  32  and the pipe joint  73 . In the present embodiment, the entire relay pipe  74  is arranged in a spiral shape, but a part of the relay pipe may extend linearly. 
     In  FIG. 10 , among a plurality of suction pads  32  arranged on the XY plane, the suction pad  32  located on the +X and −Y sides is designated as a first suction pad  32 A, the suction pad  32  located on the +X and +Y sides is designated as a second suction pad  32 B, the suction pad  32  located on the −X, +Y sides is referred to as a third suction pad  32 C, and the suction pad  32  located on the −X, −Y side is referred to as a fourth suction pad  32 D. The plurality of pipe joints  73  arranged in the X-axis direction are referred to as a first pipe joint  73 A, a second pipe joint  73 B, a third pipe joint  73 C, and a fourth pipe joint  73 D in order from the −X side to the +X side. The row in which the plurality of pipe joints  73  are lined up is closer to the row in which the second suction pad  32 B and the third suction pad  32 C are lined up than in the row in which the first suction pad  32 A and the fourth suction pad  32 D are lined up. 
     Among the first suction pad  32 A and the second suction pad  32 B located on the +X side, the first suction pad  32 A, which has a relatively long distance to the row in which a plurality of pipe joints  73  are lined up passes, is connected to the first pipe joint  73 A via the first relay pipe  74 A. The second suction pad  32 B, which has a relatively short distance to the row in which the plurality of pipe joints  73  are lined up, is connected to the second pipe joint  73 B via the second relay pipe  74 B. When viewed from the +Z direction, the first relay pipe  74 A is wound clockwise with a large diameter. The second relay pipe  74 B is wound clockwise with a diameter smaller than that of the first relay pipe  74 A. 
     Among the third suction pad  32 C and the fourth suction pad  32 D located on the −X side, the third suction pad  32 C, which has a relatively short distance to the row in which a plurality of pipe joints  73  are lined up, is connected to the third pipe joint  73 C via the third relay pipe  74 C. The fourth suction pad  32 D, which has a relatively long distance to the row in which the plurality of pipe joints  73  are lined up, is connected to the fourth pipe joint  73 D via the fourth relay pipe  74 D. When viewed from the +Z direction, the fourth relay pipe  74 D is wound counterclockwise with a large diameter. The third relay pipe  74 C is wound counterclockwise with a diameter smaller than that of the fourth relay pipe  74 D. 
     That is, among the two suction pads  32  located at the same position in the X-axis direction, the relay pipe  74  connected to the suction pad  32  located at a position relatively far from the row in which the plurality of pipe joints  73  are lined up is wound around a large circle. The relay pipe  74  connected to the suction pad  32  located at a position relatively close to the row in which the plurality of pipe joints  73  are lined up is wound in a small circle. Further, the relay pipe  74  connected to the two suction pads  32  located on the +X side and the relay pipe  74  connected to the two suction pads  32  located on the −X side are wound in opposite directions with each other. 
     Hereinafter, the operation of the robot hand  11  will be described. 
     First, an operation when switching which unit of the holding unit  21  and the suction unit  22  is used will be described. 
       FIG. 11  is a diagram showing the operation of the robot hand  11  when the units are switched. 
     As shown in  FIG. 11 , when the units are switched, the holding unit  21  and the suction unit  22  rotates integrally in the plane parallel to the first surface  20   a  of the base plate  20  (in the XZ plane) while maintaining the orientations in which the holding portion  28  and the suction portion  31  face different directions by 180°. At this time, the first holding center line H 1  of the holding unit  21  and the second holding center line H 2  of the suction unit  22  are arranged on the same straight line. 
     At the time of unit switching, the controller  13  controls the first motor  35  to the position control state, the second motor  36  to the servo lock state, the third motor  37  to the servo lock state, and the fourth motor  38  to the servo lock state. The position control state is a state in which the rotation of each motor is controlled so as to position a moving object such as a holding unit  21  at a predetermined position by a position command signal. The servo lock state is a state in which the stop position is maintained even if a force acts in the direction in which the motor rotates due to, for example, an external force. 
     When the first motor  35  rotates, as shown in  FIG. 5 , the holding unit  21  rotates in a plane (XZ plane) parallel to the first surface  20   a  of the base plate  20  via the first shaft  41 , the first gear  42 , the second gear  43 , and the second shaft  46 . At this time, the second motor  36  is in the servo-locked state, and the stopped state is maintained. Therefore, the sixth gear  66  connected to the second motor  36  on the holding unit  21  is stationary in a state of being meshed with the seventh gear  67  of the suction unit  22 . Therefore, the positional relationship between the sixth gear  66  and the seventh gear  67 , that is, the positional relationship between the holding unit  21  and the suction unit  22  does not change. As a result, the suction unit  22  is integrated with the holding unit  21  and rotates in a plane (XZ plane) parallel to the first surface  20   a  of the base plate  20 , while maintaining an orientation facing the holding unit  21  in different directions by 180°. 
     Since the first motor  35  is in the position control state, for example, when the holding unit  21  is used, the controller  13  stops the rotation of the first motor  35  at a position where the first holding center line H 1  of the holding unit  21  faces downward in the vertical direction and the second holding center line H 2  of the suction unit  22  faces upward in the vertical direction with respect to the rotation of the first motor  35 . Next, when the suction unit  22  is used, the controller  13  may stop the rotation of the first motor  35  at a position where the holding unit  21  and the suction unit  22  are integrally rotated by 180° until the second holding center line H 2  of the suction unit  22  faces downward in the vertical direction and the first holding center line H 1  of the holding unit  21  faces upward in the vertical direction. 
     When the holding unit  21  and the suction unit  22  are integrally rotated at the time of unit switching, the third motor  37  is in the servo-locked state. Therefore, as shown in  FIG. 11 , the orientation of the suction portion  31  is adjusted to the suction link portion  69 . On the other hand, the state of not tilting is maintained. Further, since the fourth motor  38  is in the servo-locked state, the two holding claws  29  are maintained in the closed state. 
     Next, the operation when changing the orientation of the holding unit  21  will be described. 
       FIG. 12  is a diagram explaining the operation of the robot hand  11  when the orientation of the holding unit  21  is changed. 
     When the orientation of the holding unit  21  is changed, the controller  13  controls the first motor  35  in the position control state, the second motor  36  in the position control state, the third motor  37  in the servo lock state, and the fourth motor  38  in the servo lock state or position. 
     As described above, the holding unit  21  is rotated by the first motor  35 . Therefore, the orientation of the holding unit  21  can be changed by rotating the holding unit  21  by the first motor  35  so that the first holding center line H 1  faces, for example, the range of −90° to +90°, with the orientation in which the first holding center line H 1  faces downward in the vertical direction is set to 0°. However, if the second motor  36  is controlled to the servo-locked state as in the case of the unit switching described above, the orientation of the suction unit  22  also changes as the orientation of the holding unit  21  changes. 
     Therefore, in the case of the present embodiment, the controller  13  controls to correct the orientation of the suction unit  22  as follows so that the orientation of the suction unit  22  does not change with the change of the orientation of the holding unit  21 . Specifically, assuming that the clockwise direction in  FIG. 12  is a positive angle and the counterclockwise direction is a negative angle, the holding unit  21  is rotated so that the first holding center line H 1  faces the direction of −θ, and the suction unit  22  is rotated by +θ. As a result, the suction unit  22  is maintained in a state in which the suction portion  31  faces upward in the vertical direction without changing its orientation. That is, the suction unit  22  is rotated with respect to the base plate  20  in a direction that cancels the change in the orientation of the suction unit  22  due to the change in the orientation of the holding unit  21 . 
     When the holding unit  21  is rotated when the orientation of the holding unit  21  is changed, since the third motor  37  is in the servo-locked state, the orientation of the suction portion  31  is maintained in a state of not being tilted with respect to the suction link portion  69 . 
     When the fourth motor  38  is in the servo-locked state, the holding unit  21  changes its orientation while maintaining the two holding claws  29  in the closed state. When the fourth motor  38  is in the position control state, the holding unit  21  changes its orientation with the two holding claws  29  opened to a predetermined position. 
     Next, the operation when changing the orientation of the suction unit  22  will be described. 
       FIG. 13  is a diagram explaining the operation of the robot hand  11  when the orientation of the suction unit  22  is changed. 
     When the orientation of the suction unit  22  is changed, the controller  13  controls the first motor  35  in the servo-locked state, the second motor  36  in the servo-locked state, the third motor  37  in the position control state, and the fourth motor  38  in the servo-locked state. 
     The suction portion  31  is rotated by the third motor  37 . Therefore, the orientation of the suction portion  31  can be changed by rotating the suction portion  31  with respect to the suction link portion  69  by the third motor  37  so that the second holding center line H 2  faces, for example, in the range of −90° to +90°, with the orientation in which the second holding center line H 2  of the suction unit  22  faces downward in the vertical direction is 0°. 
     When the suction portion  31  is rotated when the orientation of the suction portion  31  is changed, the first motor  35  is in the servo-locked state. Therefore, the orientation of the holding unit  21  is maintained in a state in which the first holding center line H 1  faces upward in the vertical direction and does not change. At this time, since the second motor  36  is in the servo-locked state, the orientation of the suction link portion  69  with respect to the base plate  20  is maintained in the unchanged state. The position of the suction link portion  69  with respect to the base plate  20  may be adjusted by setting the second motor  36  in the position controlled state. Further, since the fourth motor  38  is in the servo-locked state, the holding unit  21  maintains the state in which the two holding claws  29  are closed. 
     Hereinafter, the effects of the robot hand  11  and the picking robot  10  of the present embodiment will be described. 
     First, as the robot hand of the comparative example, it is assumed that the robot hand is provided with a holding unit and a suction unit, and each of the holding unit and the suction unit has an orientation changing function. In the robot hand of the comparative example, the first rotation axis for integrally rotating the holding unit and the suction unit when switching units, the second rotation axis for rotating the holding unit when the orientation of the holding unit is changed, and the third rotation axis for rotating the suction unit when the orientation of the suction unit is changed are arranged at different positions along the length direction of the robot hand. The first rotation axis is located between the second rotation axis and the third rotation axis. 
     In the case of the robot hand of the comparative example, the length of the robot hand is the sum of the distance from the first rotation axis to the second rotation axis, the distance from the first rotation axis to the third rotation axis, the distance from the second rotation axis to the tip of the holding unit, and the distance from the third rotation axis to the tip of the suction unit. In the case of the robot hand of the comparative example, the length of the robot hand tends to be long. If the length of the robot hand is long, there is a problem in that it easily interferes with other obstacles when moving the robot hand. 
     In response to this problem, the robot hand  11  of the present embodiment includes a unit switching/holding orientation changing mechanism  23  that switches the unit by integrally rotating the holding unit  21  and the suction unit  22  with respect to the base plate  20 , and changes the orientation of the holding unit  21  by rotating the holding unit  21  with respect to the base plate  20 . The controller  13  switches which of the holding unit  21  and the suction unit  22  is used for holding the holding object, by rotating the holding unit  21  and the suction unit  22  in a state where the holding portion  28  and the suction portion  31  face different directions from each other, the sandwiching unit  21  and the suction unit  22  are rotated, and controls to change the orientation with respect to the base plate  20  by rotating at least one of the holding unit  21  and the suction unit  22  with respect to the base plate  20 . 
     According to this configuration, the interference between the holding unit  21  and the suction unit  22  and the surrounding obstacles is suppressed, so that the robot hand  11  capable of widening the movable range can be realized. 
     Further, as shown in  FIG. 5 , the first rotation axis AX 1  when the unit is switched and the second rotation axis AX 2  when the orientation of the holding unit  21  is changed are arranged on a common axis in the length direction of the robot hand  11 . 
     That is, in the robot hand of the comparative example, three rotation axes for realizing the three operations of unit switching, the orientation change of the holding unit, and the orientation change of the suction unit are arranged at three positions in the length direction of the robot hand. On the other hand, in the robot hand  11  of the present embodiment, the three rotation axes AX 1 , AX 2 , and AX 3  for realizing the three operations of unit switching, orientation change of the holding unit, and orientation change of the suction unit are arranged at two positions in the length direction of the robot hand  11  as shown in  FIG. 4 . 
     As a result, in the case of the present embodiment, the length of the robot hand  11  is the sum of the distance from the first rotation axis AX 1  and the second rotation axis AX 2  to the third rotation axis AX 3 , the distance from the first rotation axis AX 1  and the second rotation axis AX 2  to the tip of the holding unit  21 , and the distance from the third rotation axis AX 3  to the tip of the suction unit  22 . In this way, the length of the robot hand  11  of the present embodiment can be made shorter than the length of the robot hand of the comparative example. 
     According to the configuration of the present embodiment, the length of the robot hand  11  can be shortened, so that the risk of interference with obstacles when moving the robot hand  11  can be reduced. Further, according to the configuration of the present embodiment, the movable range of the robot hand  11  can be made wider than the movable range of the robot hand of the comparative example. Further, according to the configuration of the present embodiment, it is not necessary to simplify the configuration of each unit when the robot hand  11  is miniaturized, so that the functions of the holding unit  21  and the suction unit  22  can be fully exhibited. 
     Further, the robot hand  11  of the present embodiment integrally rotates the holding portion  28  and the suction portion  31  with respect to the base plate  20  in a state of facing different directions, and holds the holding object by either the holding unit  21  or the suction unit  22 . 
     According to this configuration, it is possible to switch whether to hold the holding object by either the holding unit  21  or the suction unit  22  by a smooth operation. 
     When the rotation axis at the time of unit switching and the rotation axis at the time of changing the orientation of one of the two units are arranged on a common axis, instead of the configuration of the present embodiment, it is conceivable to arrange the first rotation axis at the time of unit switching and the third rotation axis when the orientation of the suction portion is changed on a common axis. 
     The robot hand  11  of the present embodiment employs an opening/closing structure of a holding claw  29  using a parallel link  59  as the holding unit  21 . Therefore, the distance from the second rotation axis AX 2  when the orientation of the holding unit  21  is changed to the tip of the holding unit  21  is larger than the distance from the third rotation axis AX 3  when the orientation of the suction portion  31  is changed to the tip of the suction portion  31 . As a result, when the first rotation axis AX 1  and the second rotation axis AX 2  are arranged on a common axis as in the present embodiment, the effect of shortening the length of the robot hand  11  is greater than the effect of arranging the first rotation axis AX 1  and the third rotation axis AX 3  on a common axis. 
     The robot hand  11  of the present embodiment includes a suction unit orientation correction mechanism  24  that corrects the orientation of the suction unit  22  by rotating the suction unit  22  in a direction that cancels the change in the orientation of the suction unit  22  due to the change in the orientation of the holding unit  21  when the orientation of the holding unit  21  is changed. According to this configuration, when the orientation of the holding unit  21  is changed, it is possible to suppress the change in the orientation of the suction unit  22  in conjunction with the change in the orientation of the holding unit  21 . As a result, when the holding unit  21  is used in a state where the holding unit  21  is tilted, it is possible to prevent the suction unit  22  from changing its orientation and interfering with an obstacle. 
     In the robot hand  11  of the present embodiment, the holding unit  21  and the suction unit  22  are arranged so as to overlap the first surface  20   a  of the base plate  20 . 
     As described above, according to the configuration in which the holding unit  21  and the suction unit  22  are supported by the base plate  20  by the cantilever structure, the thickness of the robot hand  11  can be reduced. Further, the projected area of the robot hand  11  as seen from the length direction (Z-axis direction) of the robot hand  11  can be reduced. As a result, interference of the robot hand  11  with obstacles can be suppressed, and the movable range can be widened. Another advantage of the cantilever structure is that, for example, when the robot hand  11  goes to pick up an article placed in the corner of the box, the robot hand  11  may be moved so that the side opposite to the side on which the base plate  20  is provided, that is, the holding unit  21  side, faces the inner surface of the box. As a result, the base plate  20  is less likely to interfere with the inner surface of the box, and the holding object P can be efficiently held. 
     In the robot hand  11  of the present embodiment, the first holding center line H 1  of the holding unit  21  and the second holding center line H 2  of the suction unit  22  are arranged on the same straight line, in an orientation in which the holding portion  28  and the suction portion  31  face directions 180 degrees different from each other. 
     According to this configuration, regardless of which of the holding unit  21  and the suction unit  22  is used, the coordinate system for controlling the position of the holding claw  29  or the suction pad  32  can be commonly used. As a result, the burden on the controller  13  related to the position control of the holding claw  29  or the suction pad  32  can be reduced. 
     Further, even if the holding portion  28  and the suction portion  31  are arranged on the same straight line and the holding portion  28  and the suction portion  31  are rotated 180 degrees to switch the functions, the tip position of one hand (for example, the holding portion  28 ) located before the rotation and the other hand (for example, the suction portion  31 ) located after the rotation are the same. That is, the holding portion  28  and the suction portion  31  are at positions symmetrical with each other. For example, if the total length of the hand is 500 mm and the first rotation axis AX 1  at the time of unit switching is located 250 mm from the tip of one hand, even if the holding portion  28  and the suction portion  31  are rotated 180 degrees, the tip of the holding claw  29  or the tip of the suction pad  32  is always 500 mm ahead when viewed from the connection position between the arm  12  and the robot hand  11 . 
     According to this configuration, the tip position of the robot hand  11  as seen from the arm  12  is the same both when it is held and when it is sucked, so it is possible to perform position control arithmetic processing without being aware of which function it currently has as a system. As a result, the load on the controller  13  can be reduced. 
     The robot hand  11  of the present embodiment further includes a suction orientation changing mechanism  25  that changes the orientation of the suction portion  31  in the suction unit  22  by rotating the suction portion  31 . 
     According to this configuration, when the suction unit  22  is used, the suction pad  32  can be made to face one surface of the holding object P placed in various orientations and positions, and the holding object P can be reliably held. 
     In the robot hand  11  of the present embodiment, the suction unit  22  is arranged so as to face the first surface  20   a  of the base plate  20 . The negative pressure supply pipe  50  for transporting the negative pressure to the suction pad  32  is connected to the inlet  79  arranged so as to face the second surface  20   b  of the base plate  20  and provided in a region of the suction unit  22  exposed to the outside from the notch  20   k  of the base plate  20 . Further, the negative pressure supply pipe  50  is arranged so as to wind from the inlet  79  side to the suction pad  32  side in the direction opposite to the direction in which the suction unit  22  rotates. 
     According to this configuration, when the suction unit  22  rotates along the first surface  20   a  of the base plate  20 , there is little risk that the negative pressure supply pipe  50  will be damaged by being sandwiched between the suction unit  22  and the base plate  20  or being pulled by an excessive force as the suction unit  22  rotates, and the reliability of the negative pressure supply pipe  50  can be improved. 
     In the robot hand  11  of the present embodiment, the relay pipe  74  that transports the negative pressure to the suction pad  32  is spirally arranged in the space between the pipe joint  73  and the suction pad  32 . 
     Assuming that the relay pipe  74  is linearly arranged in the space between the pipe joint  73  and the suction pad  32 , the relay pipe  74  may buckle when the orientation of the suction portion  31  changes. On the other hand, in the case of the present embodiment, since the relay pipe  74  is spirally wound, when the orientation of the suction portion  31  changes, the relay pipe  74  is deformed according to the orientation change of the suction portion  31  within the deformable range. As a result, buckling of the relay pipe  74  can be suppressed. 
     The picking robot  10  of the present embodiment includes a robot hand  11  that achieves the above effects. 
     According to this configuration, the picking robot  10  can hold various holding objects P placed in various orientations and situations in the box of the transport source S 1  and efficiently transport them to the transport destination S 2 , for example. 
     The robot hand  11  of the above embodiment has a pair of parallel links  59 , and includes a parallel link type holding unit  21  in which each of the two holding claws  29  opens and closes while moving up and down. Instead of this configuration, the robot hand of the embodiment may include a parallel gripper type holding unit in which the two holding claws move only in the horizontal direction. In this case, contrary to the above embodiment, the distance from the third rotation axis when changing the orientation of the suction portion to the tip of the suction portion may be longer than the distance from the second rotation axis when changing the orientation of the holding unit to the tip of the holding portion. In this case, a configuration may be adopted in which the first rotation axis when the unit is switched and the third rotation axis when the orientation of the suction unit is changed are arranged on a common axis. 
     Further, in the above embodiment, an example of a robot hand that combines two holding functions of holding and suction, that is, a so-called hybrid hand type robot hand is given. Instead of this configuration, the present invention may be applied to a robot hand provided with a plurality of holding units having the same function, for example, holding only or suction only. 
     According to at least one embodiment described above, the robot hand  11  has a holding unit  21 , a suction unit  22 , and a controller  13 . The holding unit  21  is rotatably supported by the base plate  20 . The holding unit  21  has a holding portion  28  for holding the holding object P. The suction unit  22  is rotatably supported by the base plate  20  independently of the holding unit  21 . The suction unit  22  has a suction portion  31  that holds the holding object P. The controller controls the operation of the holding unit  21  and the suction unit  22 . The controller  13  rotates the holding unit  21  and the suction unit  22  in a state where the holding portion  28  and the suction portion  31  face different directions, thereby holding either the holding unit  21  or the suction unit  22  as the holding object P. At least one of the holding unit  21  and the suction unit  22  is rotated with respect to the base plate  20  to control the orientation of the holding unit  21  and the suction unit  22  so as to change the orientation with respect to the base plate  20 . 
     As a result, it is possible to realize a robot hand  11  capable of suppressing interference between the holding unit  21  and the suction unit  22  and surrounding obstacles and widening the movable range. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover the forms and modifications that fall within the scope and spirit of the inventions.