Patent Publication Number: US-2022212884-A1

Title: Controller

Description:
TECHNICAL FIELD 
     The present invention relates to a controller for a conveyance robot arm or the like. 
     BACKGROUND ART 
     A conveyance robot including a suction pad at a distal end of its robot arm is known. In such a robot arm, negative pressure is generated in the suction pad, and a workpiece or the like, which is an object to be conveyed, is suctioned and picked up with the suction pad. When placing the object, generation of the negative pressure is stopped to release the suction. In such a type of robot arm, to pick up or place an object at an appropriate position and orientation, a sensor is installed near the suction portion of the robot arm, the position and orientation of the object before the suction pad comes into contact with the object are detected, and the movement of the suction portion is controlled based on the detection result. 
     RELATED ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: JP 2018-089719A 
       
    
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     However, in the conveyance robot as described above, the sensor installed near the suction pad detects the orientation of the object before the suction portion comes into contact with the object. For this reason, the detection of the position and the orientation of the object is easily affected by environmental disturbances (light, vibrations, or electric noise), the material, color, and the like of the object due to the characteristics of the sensor, and it is difficult to control the orientation of the suction portion with high accuracy. 
     One aspect of the present invention is to achieve a technique capable of controlling the movement of a suction pad as appropriate. 
     Means for Solving the Problems 
     To solve the above issue, a controller according to an aspect of the present disclosure includes: a deformation information obtaining unit configured to obtain information on deformation of a suction portion that suctions an object with negative pressure, and that is deformed by the negative pressure; and an operation control unit configured to control movement of the suction portion in accordance with deformation of the suction portion. 
     With the above configuration, it is possible to detect the orientation of the object by detecting the deformation of the suction portion after the suction portion has come into contact with the object. Accordingly, it is possible to achieve a controller capable of performing orientation correction with high accuracy without being affected by a disturbance environment. 
     In the controller according to one aspect of the present disclosure, the operation control unit may be configured to change an inclination of the suction portion in accordance with deformation of the suction portion. 
     With the above configuration, it is possible to detect the orientation of the workpiece after contact with the suction portion, based on the deformation of the suction portion. Accordingly, it is possible to achieve a controller capable of correcting the orientation of the workpiece with high accuracy without being affected by a disturbance environment. 
     In the controller according to one aspect of the present disclosure, the operation control unit may be configured to change an inclination of the suction portion to reduce an angle formed by a suction surface of the suction portion and a surface to be suctioned of the object. 
     With the above configuration, it is possible to detect the angle formed by the suction surface of the suction portion and the surface to be suctioned of the object, based on the deformation of the suction portion. Accordingly, it is possible to achieve a controller capable of correcting the orientation of the workpiece with high accuracy. 
     In the controller according to one aspect of the present disclosure, the operation control unit may include a contact point specifying unit configured to specify a contact point where the suction portion contacts the object based on deformation of the suction portion, and the operation control unit may be configured to change an inclination of the suction portion while maintaining contact between the suction portion and the object at the contact point. 
     With the above configuration, by changing the inclination of the suction portion while maintaining the contact between the suction portion and the object at the contact point, the suction portion and the object can be brought into intimate contact with each other. As a result, it is possible to prevent an error of picking up the object by the suction portion. 
     In the controller according to one aspect of the present disclosure, the operation control unit may be configured to rotate the suction portion within a plane including a central axis of the suction surface of the suction portion and the contact point. 
     With the above configuration, by changing the inclination of the suction portion while maintaining the contact between the suction portion and the object at the contact point, the suction portion and the object can be brought into intimate contact with each other. As a result, it is possible to prevent an error of picking up the object by the suction portion. 
     In the controller according to one aspect of the present disclosure, in a state where the suction portion is suctioning the object, the operation control unit may be configured to change the inclination of the suction portion to reduce an angle formed by a surface of the suctioned object, which is not the suctioned surface, and a surface on which the object is to be placed. 
     With the above configuration, when placing the object on the surface on which the object is to be placed, it is possible to detect the orientation of the suction portion after a part of the object has come into contact with the surface on which the object is to be placed. Accordingly, the object can be placed on the surface on which the object is to be placed with high accuracy. 
     In the controller according to one aspect of the present disclosure, the operation control unit may include a contact point specifying unit configured to specify a contact point where the object contacts the surface on which the object is to be placed, based on deformation of the suction portion, in a state where the suction portion is suctioning the object, and the operation control unit may be configured to change an inclination of the suction portion, while maintaining contact between the object and the surface on which the object is to be placed at the contact point. 
     With the above configuration, when placing the object on the surface on which the object is to be placed, it is possible to detect the orientation of the suction portion after a part of the object has come into contact with the surface on which the object is to be placed. Accordingly, the object can be placed on the surface on which the object is to be placed with high accuracy. 
     In the controller according to one aspect of the present disclosure, the operation control unit may be configured to change the speed of the suction portion in accordance with deformation of the suction portion. 
     With the above configuration, it is possible to detect that the suction portion has come into contact with a part of the object based on the deformation of the suction portion. Accordingly, by changing the speed of the suction portion after the suction portion has come into contact with a part of the object, it is possible to perform correction with high accuracy, and prevent the risk of damaging the object. 
     In the controller according to one aspect of the present disclosure, if an amount of deformation of the suction portion exceeds a first threshold value, the operation control unit may be configured to reduce a speed at which the suction portion is brought closer to the object. 
     With the above configuration, it is possible to detect that the suction portion has come into contact with a part of the object based on the deformation of the suction portion. Accordingly, by reducing the speed of the suction portion after the suction portion has come into contact with a part of the object, it is possible to perform correction with high accuracy and prevent the risk of damaging the object. 
     In the controller according to one aspect of the present disclosure, if an amount of deformation of the suction portion exceeds a second threshold value, the operation control unit may be configured to stop an operation of bringing the suction portion closer to the object. 
     With the above configuration, it is possible to detect that the suction portion is in intimate contact with the object based on the amount of deformation of the suction portion. Accordingly, the operation of bringing the suction portion closer to the object can be stopped at an appropriate timing, and the object can be prevented from being damaged. 
     In the controller according to one aspect of the present disclosure, the deformation information obtaining unit may be configured to obtain an amount of deformation and/or a speed of deformation of the suction portion, and the operation control unit may be configured to control the movement of the suction portion in accordance with the amount of deformation and/or the speed of deformation of the suction portion. 
     With the above configuration, by controlling the movement of the suction portion based on the amount of deformation and/or the speed of deformation of the suction portion, the movement of the suction portion can be controlled with high accuracy. 
     In order to solve the above issue, a control method according to one aspect of the present disclosure is a method of controlling a suction apparatus including a suction portion that suctions an object with negative pressure, and that is deformed by the negative pressure, the control method including: a deformation information obtainment step of obtaining information on deformation of the suction portion; and an operation control step of controlling movement of the suction portion in accordance with deformation of the suction portion. 
     With the above configuration, effects similar to those of the controller according to an embodiment of the present invention can be obtained. 
     Effects of the Invention 
     According to one aspect of the present invention, it is possible to detect an amount of deformation of the suction portion after the suction portion has come into contact with an object, and correct the orientation of the suction portion based on the amount of deformation of the suction portion. Accordingly, it is possible to provide a controller capable of controlling the movement of the suction portion with high accuracy without being affected by a disturbance environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating an example of an application situation of a mobile suction apparatus according to an embodiment. 
         FIG. 2  is a schematic diagram illustrating an example of a suction pad (suction portion) and a deformation detection unit in the mobile suction apparatus according to the embodiment. 
         FIG. 3  is a schematic diagram illustrating an example of a hardware configuration of the mobile suction apparatus according to the embodiment. 
         FIG. 4  is a diagram illustrating an example of a situation to which the present invention is applied. 
         FIG. 5  is a diagram illustrating an example of a situation to which the present invention is applied. 
         FIG. 6  is a diagram illustrating an example of a situation to which the present invention is applied. 
         FIG. 7  is a diagram illustrating the definition of an amount of deformation of the suction pad that is used in the embodiment of the present invention. 
         FIG. 8  is a diagram illustrating another definition of an amount of deformation of the suction pad that is used in the embodiment of the present invention. 
         FIG. 9  is a diagram illustrating orientation control of the suction pad according to the embodiment of the present invention. 
         FIG. 10  is a flowchart showing the operation of a controller  5  in the embodiment of the present invention. 
         FIG. 11  is a flowchart showing the operation of a controller  5  in another embodiment of the present invention. 
         FIG. 12  is a flowchart showing the operation of a controller  5  in still another embodiment of the present invention. 
         FIG. 13  is a flowchart showing the operation of a controller  5  in still another embodiment of the present invention. 
         FIG. 14  is a side view illustrating orientation control of the suction pad corresponding to  FIG. 13   
         FIG. 15  is a flowchart showing the operation of a controller  5  in still another embodiment of the present invention. 
         FIG. 16  is a side view illustrating orientation control of the suction pad corresponding to  FIG. 15 . 
         FIG. 17  is a block diagram illustrating an example of a schematic configuration of a suction apparatus including a controller  5  according to a modified example. 
         FIG. 18  is a flowchart illustrating the operation of the suction apparatus including the controller  5  according to the modified example. 
         FIG. 19  is a schematic diagram illustrating an example of a process flow of the suction apparatus including the controller  5  according to the modified example. 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     Hereinafter, an embodiment according to one aspect of the present invention (hereinafter, also referred to as “present embodiment”) will be described with reference to the drawings. 
     1. Application Example 
       FIG. 1  schematically illustrates an example of an application situation of a controller  5  according to the present embodiment.  FIG. 2  schematically illustrates an example of a suction pad (suction portion)  112  and a deformation information obtaining unit  113  in a mobile suction apparatus  100  in which the controller  5  according to the present embodiment is installed. Specifically,  FIG. 2 ( a )  schematically illustrates an example of a top view of the suction pad  112  and the deformation information obtaining unit  113 . Also,  FIG. 2 ( b )  schematically illustrates an example of a side view of the suction pad  112  and the deformation information obtaining unit  113 . 
     In the example of  FIG. 1 , the mobile suction apparatus  100  includes a suction apparatus  1  and a conveyance unit (automated guided vehicle)  2 . The suction apparatus  1  includes a robot arm  11 , a vacuum pump  12 , and a manipulator control unit  13 . The conveyance unit  2  moves (conveys) the mobile suction apparatus  100 . The conveyance unit  2  includes a negative pressure control unit  21  that controls the vacuum pump that generates negative pressure (air pressure), and an automated guided vehicle  22 . There is no limitation to the mobile suction apparatus  100  as long as the mobile suction apparatus  100  includes the suction apparatus  1  that includes the suction pad  112  that is deformed by negative pressure. An example of the mobile suction apparatus  100  is a vacuum suction system such as a mobile robot. In addition, the suction apparatus  1  can be applied not only to the mobile suction apparatus  100  such as a mobile robot, but also to a fixed suction apparatus. 
     The robot arm  11  performs a gripping operation by suctioning an object with negative pressure. The robot arm  11  includes the suction pad  112  and a manipulator unit  111  that performs a gripping operation of an object by causing the suction pad  112  to suction the object. An example of the suction pad  112  is a suction pad (vacuum pad) that is provided with a suction cup. The robot arm  11  including the manipulator unit  111  and the suction pad  112  can suitably suction and grip an object. The object may be any object that is gripped by being suctioned by the robot arm  11  with negative pressure, and an example of such an object is a workpiece. 
     As illustrated in the example of  FIG. 2 , the deformation information obtaining unit  113  that detects deformation of the suction pad  112  may also be disposed on (attached to) the suction pad  112 . Also, as illustrated in the example of  FIG. 2 , the deformation information obtaining unit  113  may also include a strain sensor (strain gauge)  114  that is disposed on the suction pad  112 . A strain measuring gauge terminal may also be included. The deformation information obtaining unit  113  may include one strain sensor  114 , but may also include a plurality of (three, for example) strain sensors  114   a ,  114   b , and  114   c  as illustrated in the example of  FIG. 2 . In this case, the deformation information obtaining unit  113  detects deformation (at least one of an amount of deformation and a speed of deformation (differential of the amount of deformation) of the suction pad  112 , for example) at a plurality of locations in the suction pad  112 . With this configuration, the deformation of the suction pad  112  can be detected better. 
     Hereinafter, with reference to  FIGS. 2 to 4 , an application situation of the mobile suction apparatus  1  that is provided with the above controller  5  will be described in detail. 
     (1) Picking Up an Object 
       FIG. 4  is a schematic diagram illustrating a situation in which one workpiece W is picked up with the suction pad  112 , from among a plurality of objects (workpieces) placed on a table. First, an example in which the present invention is applied to picking up an object will be described with reference to  FIG. 4 . 
       FIG. 4( a )  shows a state of picking up an object in a conventional example, and  FIG. 4( b )  shows a state of picking up an object in an aspect of the present invention. 
     In  FIG. 4( a ) , the controller of the conveyance robot lowers the robot arm including the suction pad  112  in the vertical direction to bring the suction pad  112  closer to a workpiece W placed on the table. Then, when the suction surface (suction plane) of the suction pad  112  and the surface to be suctioned of the workpiece W have come into contact with each other over the entire surface, the surface to be suctioned of the workpiece W is suctioned with negative pressure of the suction pad  112 , and the suction surface of the suction pad  112  and the surface to be suctioned of the workpiece W are brought into intimate contact with each other. The controller performs control such that the robot arm lifts the workpiece W and conveys the workpiece W to a desired location in a state where the workpiece W is being suctioned by the suction pad  112 . 
     Here, the controller obtains in advance position information (foresight information) of the surface S 1  to be suctioned (indicated by a dotted line) of the workpiece W placed on the table. On the basis of the foresight information, the controller controls the suction pad  112  to bring the suction surface of the suction pad  112  into intimate contact with the surface to be suctioned of the workpiece W in parallel. 
     However, the foresight information (position information and orientation information of the surface S 1  to be suctioned of the workpiece W) obtained from an image or the like captured by a camera often includes an error. Here, the position information has three degrees of freedom including not only position information in a plane direction, but also position information in a vertical direction. The orientation information indicates the inclination of the surface S 1  to be suctioned. The position and orientation of the surface S 1  to be suctioned of the workpiece W indicated by the foresight information may not coincide with the actual position and orientation of the surface S 2  to be suctioned of the workpiece W. In the situation shown in  FIG. 4( a ) , for example, the left side of the workpiece W overlaps with the adjacent object, and is placed in a state in which it is lifted from the table. Accordingly, the actual surface to be suctioned of the workpiece W is positioned in S 2  indicated by the solid line in  FIG. 4( a ) . As a result, even if the controller tries to suction the workpiece W based only on the foresight information, the suction surface of the suction pad  112  and the actual surface S 2  to be suctioned do not coincide with each other, and the suction surface of the suction pad  112  and the surface to be suctioned of the workpiece W do not come into contact with each other over the entire surface. Accordingly, if the suction pad  112  is controlled to suction the workpiece W in the above-described state, air leaks from a portion where the right side of the workpiece W and the suction pad  112  are not in contact with each other, and the suction pad  112  cannot normally pick up the workpiece W. As a result, an error of picking up the workpiece W occurs. 
     In contrast, the controller  5  of the present embodiment controls, after bringing the suction pad  112  closer to the workpiece W based on the foresight information, the movement of the suction pad  112  in accordance with the deformation of the suction pad  112 . In  FIG. 4( b ) , when the suction pad  112  and the surface to be suctioned of the workpiece W are brought into contact with each other at a contact point C, a part of the suction pad  112  is deformed. The controller  5  specifies the position of the contact point C, based on the deformation of the suction pad  112 . When only a part of the suction pad  112  is deformed or the deformation is biased, the controller  5  detects that the suction surface of the suction pad  112  and the surface to be suctioned of the workpiece W are not in contact with each other (do not coincide with each other) over the entire surface. In this case, the controller  5  changes the inclination of the suction pad  112  while maintaining the contact between the suction pad  112  and the workpiece W at the contact point C. That is to say, the controller  5  changes the inclination of the suction pad  112  to reduce the angle formed by the suction surface of the suction pad  112  and the surface to be suctioned of the workpiece W with the contact point C as a fulcrum. 
     The controller  5  further controls the suction pad  112  to suction and pick up the workpiece W, when the suction pad  112  is uniformly deformed (the angle between the suction surface of the suction pad  112  and the surface to be suctioned of the workpiece W becomes zero) and the suction surface of the suction pad  112  and the surface to be suctioned of the workpiece W are in contact with each other over the entire surface. 
     As described above, when the controller  5  of the present embodiment is applied to a conveyance robot and the suction pad  112  that is attached to the distal end of the robot arm of the conveyance robot picks up an object placed on the table, the controller  5  specifies the position of the contact point C after the suction pad  112  has come into contact with one point of the surface to be suctioned of the object. Thereafter, the controller  5  controls the movement of the suction pad  112  so that the suction surface of the suction pad  112  and the surface to be suctioned of the object come into intimate contact with each other while maintaining the contact at the contact point C, and causes the suction pad  112  to suction the object. As a result, the object can be reliably picked up, and the risk of damaging the object due to a pick-up error can be prevented. 
     (2) Pressing an Object 
       FIG. 5  shows a situation in which the suction pad  112  is pressed against the workpiece W placed on the table.  FIG. 5( a )  shows a state of pressing in the conventional example, and  FIG. 5( b )  shows a state of pressing in the application example of the present invention. 
     In  FIG. 5( a ) , the controller of the conveyance robot lowers the robot arm including the suction pad  112  in the vertical direction, brings the suction pad  112  closer to the workpiece W placed on the table, and presses the upper surface of the workpiece W with an appropriate pressure. Thereafter, the controller stops lowering the suction pad  112 . 
     Here, position information and orientation information (foresight information) of the upper surface S 1  of the workpiece W normally placed on the table are stored in advance in the controller. The controller brings the suction pad  112  closer to the upper surface of the workpiece W based on the foresight information, and presses the suction pad  112  onto the workpiece W at an appropriate distance. 
     However, the actual upper surface S 2  of the workpiece W may be lower than the upper surface S 1  as shown on the left side of  FIG. 5( a ) , or may be higher than the upper surface S 1  as shown on the right side of  FIG. 5( a ) . Accordingly, in the configuration in which the controller controls the suction pad  112  based only on the foresight information, if the actual upper surface S 2  of the workpiece W is lower than the upper surface S 1  as shown on the left side of  FIG. 5( a ) , the suction of the suction pad  112  is started in a state where the suction pad  112  does not sufficiently press against the workpiece W. As a result, the amount of pressing (distance of pressing) is insufficient, and the pick-up of the workpiece W fails. On the other hand, as shown on the right side of  FIG. 5( a ) , if the actual upper surface S 2  of the workpiece W is higher than the upper surface S 1 , even if the suction pad  112  reaches the workpiece W, the suction pad  112  does not stop, and continues to press against the upper surface of the workpiece W. As a result, the amount of pressing is excessive, and there is a risk that the workpiece W and/or the suction pad  112  may be damaged. 
     In contrast, in the controller  5  of the present embodiment, as shown in  FIG. 5( b ) , when the suction pad  112  is brought closer to the workpiece W, the position and the orientation of the suction pad  112  are corrected while observing the amount of pressing of the suction pad  112  with respect to the workpiece W. As a result, the amount of pressing of the suction pad  112  against the workpiece W can be kept constant. 
     (3) Placing an Object 
       FIG. 6  shows a situation where the workpiece W that is in a state in which it is suctioned by the robot arm is placed on a table.  FIG. 6( a )  shows a state of placing an object in a conventional example, and  FIG. 6( b )  shows a state of placing an object in an application example of the present invention. 
     In  FIG. 6( a ) , the controller lowers the robot arm in a state where the workpiece W is being suctioned by the suction pad  112  in the vertical direction to bring the workpiece W closer to the table. Then the suction of the suction pad  112  is released, and the workpiece W is placed on the surface of the table on which workpiece W is to be placed. 
     Here, the controller obtains in advance the position S 1  of the surface of the table on which the workpiece W is to be placed as the foresight information. The controller of the conventional example determines, based on the foresight information, that the bottom surface of the workpiece W has reached the position S 1 , and the workpiece W and the surface of the table on which the workpiece W is to be placed have come into contact with each other over the entire surface. Thereafter, the controller performs control to release the suction of the suction pad  112 , and place the workpiece W on the table. 
     However, in the situation shown in  FIG. 6( a ) , the position S 1  of the surface on which the workpiece W is to be placed that is obtained based on the foresight information does not coincide with the actual position S 2  of the surface on which the workpiece W is to be placed. In this case, if the suction by the suction pad  112  is released and the workpiece W is placed when the bottom surface of the workpiece W reaches the position S 1 , the workpiece W is not placed at the correct position. Also, the workpiece W may fall to the actual position S 2  of the surface on which the workpiece W is to be placed, and may be damaged. Furthermore, even if a part of the workpiece W comes into contact with the actual surface on which the workpiece W is to be placed, the lowering of the robot arm may be continued. As described above, the workpiece W and/or the suction pad  112  may be damaged. 
     In contrast, as shown in  FIG. 6( b ) , the controller  5  of the present embodiment corrects the orientation of the suction pad  112  based on the deformation of the suction pad  112 . In  FIG. 6( b ) , the suction pad  112  is deformed when the workpiece W comes into contact with the contact point C′ of the surface of the table on which the workpiece W is to be placed. The controller  5  specifies the position of the contact point C′ based on the deformation of the suction pad  112 . When the amount of deformation of a part of the suction pad  112  is changed or when the deformation is biased, the controller  5  detects that the lower surface of the workpiece W and the surface of the table on which the workpiece W is to be placed are not in contact with each other over the entire surface. In this case, the controller  5  changes the inclination of the suction pad  112  to reduce the angle formed by the surface of the suctioned workpiece W, which is not the suctioned surface (that is to say, lower surface of the workpiece W), and the surface of the table on which the workpiece W is to be placed. In other words, the controller  5  changes the inclination of the suction pad  112  to reduce the angle formed by the suction surface of the suction pad  112  and the surface of the table on which the object is to be placed, that is to say, to reduce the angle formed by the bottom surface of the workpiece W and the surface of the table on which the workpiece W is to be placed, with the contact point C′ as a fulcrum. Note, that the controller  5  has information on the shape, the size, and the like of the workpiece W. 
     When the workpiece W that is suctioned by the suction pad  112  is to be placed on the surface of the table on which the workpiece W is to be placed, the controller  5  of the present embodiment specifies the position of the contact point C′ after the lower surface of the workpiece W has come into contact with the surface of the table on which the workpiece W is to be placed at one point. Thereafter, the controller  5  controls the movement of the suction pad  112  so that the lower surface of the workpiece W and the surface of the table on which the workpiece W is to be placed come into intimate contact with each other while maintaining the contact at the contact point C′, and then release the suction of the workpiece W. In this manner, the workpiece W can be placed at an appropriate position, and the object can be prevented from being damaged due to a misplacement. 
     2. Configuration Example 
     Mobile Suction Apparatus 
     Next, with reference to  FIGS. 3( a ) and 3( b ) , an example of a hardware configuration of the mobile suction apparatus  100  including the controller  5  according to the present embodiment will be described. 
       FIG. 3  is a block diagram schematically illustrating an example of the configuration of the mobile suction apparatus  100  according to the present embodiment. In the example shown in  FIG. 3 , the mobile suction apparatus  100  according to the present embodiment includes a suction apparatus  1 , a conveyance unit  2 , and a battery  3 . 
     Suction Apparatus 
     The suction apparatus  1  includes a robot arm  11 , a vacuum pump  12 , and an operation control unit (manipulator control unit)  13 . 
     Robot Arm 
     In the example shown in  FIG. 2 , the robot arm  11  includes a manipulator unit  111 , a suction pad  112 , a deformation information obtaining unit  113 , and the operation control unit. 
     Manipulator Unit 
     The manipulator unit  111  is driven together with the suction pad  112  of the robot arm  11 , under the control of the operation control unit  13 . The manipulator unit  111  includes, for example, one or more joints. 
     Suction Pad 
     When the suction pad  112  is positioned at the work position by the driving of the manipulator unit  111 , the suction pad  112  performs an operation of gripping an object by suctioning the object with negative pressure corresponding to the amount of driving of the vacuum pump  12 . 
     Deformation Information Obtaining Unit 
     The deformation information obtaining unit  113  obtains information on deformation of the suction pad  112 . The deformation information obtaining unit  113  obtains, for example, data indicating strain of the suction pad  112  from the strain sensor  114 . The deformation information obtaining unit  113  specifies the amount of deformation of the suction pad  112  based on the data indicating the strain. A specific example of the amount of deformation will be described later. 
     As illustrated in the examples of  FIGS. 2 and 3 , the deformation information obtaining unit  113  may also obtain information on deformation at a plurality of locations in the suction pad  112  from a plurality of strain sensors  114   a ,  114   b , and  114   c . However, in the present embodiment, there is no particular limitation to the deformation information obtaining unit  113  as long as the deformation information obtaining unit  113  can obtain information on deformation of the suction pad  112 . In the present embodiment, the deformation information obtaining unit  113  may also obtain the deformation information from, for example, one or more sensors disposed on or built in the suction pad  112 . Because the sensor is disposed on or built in the suction pad  112 , the deformation of the suction pad  112  can be suitably detected. When the sensor is built in the suction pad  112 , as shown in the example of  FIG. 2 , the sensor can be built in the suction pad  112  corresponding to the place of the suction pad  112  where the strain sensor  114  is disposed. Examples of the sensor that is built in the suction pad  112  include a strain gauge sensor and a pressure-sensitive conductive sensor that is made of rubber or resin containing a conductive material such as carbon nanotubes and carbon particles. 
     As an example, the deformation information obtaining unit  113  may also obtain deformation information from one or more optical displacement meters (distance sensors such as laser displacement meters) or shape measurement sensors, instead of the strain sensor  114 . In the example of  FIG. 2 , for example, one or more optical displacement meters or shape measurement sensors are disposed on the suction pad  112  similarly to the strain sensors  114 . Also, as shown in the example of  FIG. 2( b ) , the optical displacement meter or the shape measurement sensor detects the light reflected by the suction pad  112  and measures the amount of displacement of the suction pad  112 , so that the deformation of the suction pad  112  can be suitably detected (measure the shape change). In particular, even in a case where one two-dimensional shape measurement sensor is disposed on the suction pad  112 , the two-dimensional shape measurement sensor can detect deformation at a plurality of locations in the suction pad  112 . Examples of the optical displacement meter include a low-cost single-distance displacement sensor. Examples of the shape measurement sensor include a two-dimensional shape measurement sensor that is a smart sensor. 
     As another example, the deformation information obtaining unit  113  may also include a proximity sensor, instead of the strain sensor  114 . When the deformation information obtaining unit  113  includes a proximity sensor, for example, one or more proximity sensors are disposed on the suction pad  112  in the same manner as the strain sensors  114  illustrated in  FIG. 2 . Also, the proximity sensor can preferably detect the deformation of the suction pad  112  (measure the shape change) by measuring the amount of displacement of the distance between the proximity sensor and the suction pad  112 . Examples of the proximity sensor include an ultrasonic sensor, an inductive proximity sensor, a capacitive proximity sensor, and an optical proximity sensor. 
     Alternatively, the deformation information obtaining unit  113  may also obtain information on the amount of deformation, the speed of deformation, or the acceleration of deformation from a sensor capable of detecting deformation of the suction portion  112 , such as the strain sensor  114 , as the information on deformation. In this case, the strain sensor  114  performs a process for obtaining the amount of deformation, the speed of deformation, or the acceleration of deformation. 
     The deformation information obtaining unit  113  outputs deformation data such as the amount of deformation, the speed of deformation, or the acceleration of deformation of the suction pad  112  to the manipulator control unit  13  and the negative pressure control unit  21 . 
     Abnormality Determination Unit 
     An abnormality determination unit  115  determines that the object is stuck to the suction pad  112 , if the amount of deformation of the suction pad  112  after a predetermined period of time has elapsed since the suction pad  112  stopped suctioning the object and has separated the object is greater than or equal to a second threshold value. In other words, the abnormality determination unit  115  determines that the object is stuck to the suction pad  112 , if the amount of deformation of the suction pad  112  after a predetermined period of time has elapsed since the space between the suction pad  112  and the object is no longer in the vacuum state (that is to say, the vacuum is broken) is greater than or equal to the second threshold value. 
     In this case, the abnormality determination unit  115  can issue an alert or cause the suction pad  112  to perform an operation of dropping the object (placing operation). In this manner, it is possible to prevent a failure of the placement due to the fact that the object does not separate from the suction pad  112  because it is stuck to the suction pad  112  after a vacuum breakdown. 
     Vacuum Pump 
     The vacuum pump  12  generates negative pressure according to the amount of driving, and provides the negative pressure to the suction pad  112 . Here, an example in which the suction apparatus  1  in the mobile suction apparatus  100  includes the vacuum pump  12  will be described. In the present embodiment, the suction apparatus  1  in the mobile suction apparatus  100  may not include the vacuum pump  12 , and for example the vacuum pump  12  may also be provided outside the suction apparatus  1  and the mobile suction apparatus  100 . Also with this configuration, the negative pressure control unit  21  controls the amount of driving of the vacuum pump  12 , so that the same effects as those of the above-described example can be achieved. 
     Operation Control Unit 
     The operation control unit  13  includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), or the like, and preforms control in response to an information process. The manipulator control unit  13  controls the manipulator unit  111  of the robot arm  11 , based on the manipulator control signal output from the negative pressure control unit  21 . In this manner, the manipulator control unit  13  moves the suction pad  112  using the manipulator unit  111 . Specifically, the manipulator control unit  13  drives the manipulator unit  111  so that the suction pad  112  of the robot arm  11  is positioned at a work position where the suction pad  112  can suction the object. Also, the manipulator control unit  13  may also operate the manipulator unit  111  so that the angle of the suction pad  112  with respect to the object reaches a predetermined angle after the suction pad  112  is positioned at the work position. In this manner, the position of the suction pad  112  can be finely adjusted to a more suitable position. In addition, after the suction pad  112  has suctioned the object, the manipulator control unit  13  drives the manipulator unit  111  so that, for example, the suction pad  112  of the robot arm  11  is positioned at the position of a predetermined box (not illustrated) installed on the upper portion of the manipulator control unit  13 . 
     Furthermore, the manipulator control unit  13  may also determine the direction in which the suction pad  112  is moved to suction the object again, based on a plurality of amounts of deformation at a plurality of positions in the suction pad  112 . 
     In the pick-up operation (suction operation) of the object by the suction pad  112 , the mobile suction apparatus  100  measures the positional relationship between the object and the mobile suction apparatus  100  by two-dimensional vision, three-dimensional vision, or the like, and the suction pad  112  performs the pick-up operation of the object, in order to prevent variation in the stop position of the mobile suction apparatus  100  after traveling of the mobile suction apparatus  100 . In this case, there is a risk that an error in picking up the object by the suction pad  112  may occur due to a measurement error in the positional relationship between the object and the mobile suction apparatus  100 . 
     In contrast, with the above-described configuration, even when the suction pad  112  is not in intimate contact with the object, the suction pad  112  can be moved in the direction in which the object is suctioned again. As a result, it is possible to prevent an error of picking up the object with the suction pad  112 . 
     If the amount of deformation of the first portion is larger than the amount of deformation of the second portion among the plurality positions of the suction pad  112 , the manipulator control unit  13  may also move the suction pad  112  to the first portion side (the side opposite to the placement position of the sensor that has detected the smaller amount of deformation) from the second portion, in order to suction the object again. In this manner, it is possible to suction position of the suction pad  112  from being misaligned. As a result, it is possible to better prevent an error of picking up the object with the suction pad  112 . 
     Conveyance Unit 
     The conveyance unit (automated guided vehicle)  2  includes a negative pressure control unit (control signal output unit)  21  and an automated guided vehicle  22 . 
     Negative Pressure Control Unit 
     The negative pressure control unit  21  includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), or the like, and preforms control in response to an information process. The negative pressure control unit  21  includes, for example, a programmable logic controller (PLC) or a microcontroller. The negative pressure control unit  21  controls the vacuum pump  12  that generates negative pressure, based on an output signal received from one or more strain sensors  114  of the deformation information obtaining unit  113  and a conveyance state signal received from the conveyance control unit  221  of the automated guided vehicle  22 . 
     The negative pressure control unit  21  controls ON and OFF of the vacuum pump  12  based on a signal that is output from the operation control unit  13 . If it is determined from the deformation of the suction pad  112  that the suction pad  112  has sufficiently pressed the object when picking up the object, for example, the negative pressure control unit  21  turns ON the vacuum pump. Also, when the object is to be placed on the table, if the operation control unit  13  determines that the entire bottom surface of the object is in contact with the surface of the table on which the object is to be placed, the negative pressure control unit  21  turns OFF the vacuum pump. 
     In addition, the negative pressure control unit  21  outputs a manipulator control signal for causing the manipulator control unit  13  to control the manipulator unit  111 . 
     Furthermore, the negative pressure control unit  21  may also include an analog signal output unit  211  that outputs an analog signal as a control signal for the vacuum pump  12 . The analog signal output unit  211  may also perform control to monotonically increase or monotonically decrease the analog signal. In this manner, the amount of driving of the vacuum pump  12  can be changed in a slope shape, so that a rush current can be reduced. In addition, power consumption can be reduced and control can be stabilized. 
     Automated Guided Vehicle 
     In the example of  FIG. 3 , the automated guided vehicle  22  includes a conveyance control unit  221 . The conveyance control unit  221  controls the movement (conveyance) of the mobile suction apparatus  100  by controlling the conveyance of the automated guided vehicle  22 . The conveyance control unit  221  moves, for example, the mobile suction apparatus  100  to a work position where the robot arm  11  can grip the object. Also, when the mobile suction apparatus  100  has already been positioned at the work position, the conveyance control unit  221  does not move the mobile suction apparatus  100 . In addition, the automated guided vehicle  22  transmits a conveyance state signal, which is a signal indicating the conveyance state of the automated guided vehicle  22 , to the negative pressure control unit  21 . 
     Battery 
     The battery  3  controls the units of the mobile suction apparatus  100 , that is to say, the suction apparatus  1  and the conveyance unit  2 , by supplying power to these units of the mobile suction apparatus  100 . 
     In the above example, the mobile suction apparatus  100  is configured to operate with the battery  3 , but there is no limitation to this configuration. In the present embodiment, the mobile suction apparatus  100  may also be configured such that power is supplied from the outside of the mobile suction apparatus  100  through a power cord. 
     Controller 
     As described above, the controller  5  includes the deformation information obtaining unit  113  that obtains information on the deformation of the suction pad  112 , and the operation control unit  13  that controls the movement of the suction pad  112  in accordance with the deformation of the suction pad  112 . In other words, the operation control unit  13  changes the movement (movement direction, speed, and/or inclination) of the suction pad  112  in accordance with the deformation of the suction pad  112 . 
     The controller  5  further includes an object information obtaining unit  14  that obtains information about an object, and a placement information obtaining unit  15  that obtains information about a table on which the object is to be placed. 
     The controller  5  may be provided in the mobile suction apparatus  100 , or may also be provided separately from the mobile suction apparatus. The controller  5  may also be configured to be capable of communicating with the mobile suction apparatus, and to transmit a control signal for controlling the mobile suction apparatus to the mobile suction apparatus, for example. 
     Operation Control Unit 
     The operation control unit  13  may further include a contact point specifying unit  131 . The contact point specifying unit  131  specifies a contact point where the suction pad  112  contacts the object, based on the deformation (amount of deformation, speed of deformation, or acceleration of deformation) of the suction pad  112 . In addition, the contact point specifying unit  131  specifies a contact point where the object contacts the surface on which the object is to be placed, based on the deformation (amount of deformation, speed of deformation, or acceleration of deformation) of the suction pad  112  in a state where the suction pad  112  is suctioning the object. According to the above configuration, even if there is a measurement error in the position and orientation relationship between the object and the mobile suction apparatus  100 , the measurement error can be canceled by the manipulator control unit  13  causing the manipulator unit  111  to tilt the orientation of the suction portion (suction pad)  112  toward the suction surface side taking the contact point that is specified by the contact point specifying unit  131  as a fulcrum. As a result, it is possible to better prevent an error of picking up the object by the suction portion  112 . This will be described in detail later. 
     3. Operation Examples 
     Hereinafter, various operation examples of the controller  5  according to the present invention will be described. 
     Before describing specific operation examples, the definition of the amount of deformation of the suction pad  112  will be described. 
     Definition of Amount of Deformation of Suction Pad  112   
     Next, the definition of the amount of deformation of the suction pad  112  will be described with reference to  FIGS. 7 and 8 . 
       FIG. 7  is a diagram illustrating the definition of the amount of deformation of the suction pad that is used in the embodiment of the present invention. First, the definition  1  of the amount of deformation of the suction pad  112  will be described with reference to  FIG. 7 . 
     As described above, the suction pad  112  has a substantially conical shape whose lower side (suction surface) Q is open. Here, a plane including a circular end portion of the suction pad  112  that is to be brought into contact with an object is referred to as “suction surface”. Also, the X-axis and the Y-axis extend in two directions perpendicular to each other and parallel to the suction surface of the suction pad when it is not deformed, and the Z-axis extends in a direction normal to the suction surface of the suction pad when it is not deformed. In the definition  1  of the amount of deformation of the suction pad  112 , the inclination of the suction surface of the suction pad  112  is represented by the amount of rotation Mx about the X-axis and the amount of rotation My about the Y-axis. In the definition  1 , the amount of deformation of the suction pad  112  is represented by Mx, My, and the amount of pressing Z in the Z-axis direction. 
       FIG. 8  is a diagram illustrating the definition of the amount of deformation of the suction pad that is used in the embodiment of the present invention. Next, a definition  2  of the amount of deformation of the suction pad  112  will be described with reference to  FIG. 8 . 
     A vector connecting the center of the suction surface of the suction pad when it is not deformed and the center of the suction surface of the suction pad when it is deformed is defined as R. In addition, the unit normal vector on the suction surface of the suction pad when it is deformed is defined as N. In the definition  2 , the projection of the vector N onto the X-axis is denoted by ex, the projection of the vector N onto the Y-axis is denoted by ey, and the projection of the vector R onto the Z-axis is denoted by ez. In other words, in the definition  2 , the X-axis component of the vector N is ex, the Y-axis component of the vector N is ey, and the Z-axis component of the vector R is ez. In the definition  2 , the amount of deformation of the suction pad  112  is represented by {ex, ey, ez}. 
     As for the amount of deformation of the suction pad  112 , an equivalent amount of information can be obtained by the definition  1  and the definition  2 , but the definition  2  is used in the following description. 
     Hereinafter, with reference to  FIGS. 10 to 16 , operations such as picking up and placing of the workpiece W by the mobile suction apparatus  100  installed in the controller  5  of the present invention will be described. 
     Operation Example 1 
       FIG. 10  is a flowchart showing the operation of the controller  5  in the embodiment of the present invention. First, with reference to  FIG. 10 , an operation example in which the suction pad  112  suctions a workpiece W and picks up the workpiece W will be described. 
     Step S 10   
     First, in step S 10 , the operation control unit  13  causes the suction pad  112  to approach the workpiece W by lowering the suction pad  112  in the vertical direction. 
     Step S 12   
     Next, in step S 12 , the operation control unit  13  determines whether or not at least a part of the suction pad  112  has come in contact with the workpiece W. When the suction pad  112  has come into contact with the workpiece W, the suction pad  112  is inclined in the X and Y directions, and the amount of inclination of the suction pad  112  represented by the absolute value of the vector (ex, ey) exceeds a threshold value ε 1  or the amount of pressing ez in the Z-axis direction exceeds a threshold value ε 2 . Accordingly, the following expression is satisfied: 
       |( ex,ey )|&gt;ε1, or  ez&gt;ε 2
 
     Therefore, more specifically, in this step, the operation control unit  13  determines that the suction pad  112  has come into contact with the workpiece W if the above expression is satisfied, and otherwise determines that the suction pad  112  has not come into contact with the workpiece W. 
     If the operation control unit  13  determines that the suction pad  112  has come into contact with the workpiece W (YES in step S 12 ), the process proceeds to step S 14 . 
     If the operation control unit  13  does not determine that the suction pad  112  has not come into contact with the workpiece W (NO in step S 12 ), the process returns to step S 10  and the operation control unit  13  continues the approach of the suction pad  112  to the workpiece W. 
     Step S 14   
     Next, in step S 14 , the operation control unit  13  determines whether or not the suction pad  112  and the workpiece W are entirely in contact with each other. When the suction pad  112  is entirely in contact with the workpiece W, the inclination of the suction pad  112  is eliminated, so that the following expression is satisfied. 
       |( ex,ey )|&lt;ε1
 
     Therefore, in this step, the operation control unit  13  determines that the suction surface of the suction pad  112  is entirely in contact with the workpiece W if the above expression is satisfied, and otherwise determines that the suction surface of the suction pad  112  is not entirely in contact with the workpiece W. 
     If the operation control unit  13  determines that the suction surface of the suction pad  112  and the workpiece W are entirely in contact with each other (YES in step S 14 ), the operation control unit  13  completes the control of the inclination of the suction pad  112  and shifts to the control of the amount of pressing described later. 
     If the operation control unit  13  does not determine that the suction surface of the suction pad  112  and the workpiece W are entirely in contact with each other (NO in step S 14 ), the process proceeds to step S 16 . 
     Step S 16   
     In step S 16 , the contact point specifying unit  131  specifies the position of the contact point C between the suction pad  112  and the workpiece W, based on the deformation of the suction pad  112 . 
       FIG. 9( a )  is a side view of the suction pad  112 , and  FIG. 9( b )  is a top view of the suction pad  112 . Here, with reference to  FIG. 9 , a process of specifying the position of the contact point C between the suction pad  112  and the workpiece W that is performed by the contact point specifying unit  131  will be described with reference to  FIG. 9 . Letting an angle formed by a projection of the inclination (vector N) of the suction pad  112  onto the XY plane and the X-axis be θ, θ is obtained from the following expression. 
       θ=arctan( ey/ex )
 
     The contact point specifying unit  131  specifies a contact point C between the suction pad  112  and the workpiece W based on θ. 
     Once the contact point is specified, the process proceeds to step S 18 . 
     Step S 18   
     In step S 18 , the operation control unit  13  changes the inclination of the suction pad  112  while maintaining the contact between the suction pad  112  and the workpiece W at the specified contact point C. That is to say, the operation control unit  13  changes the inclination of the suction pad  112  to reduce the angle between the suction surface of the suction pad  112  and the surface to be suctioned of the workpiece W. Here, the operation control unit  13  obtains, by the following process, an operation command of the manipulator unit  111  in a case where the inclination of the suction pad  112  is changed to align the suction surface of the suction pad  112  with the surface to be suctioned of the workpiece W while maintaining the contact at the contact point. 
     The suction pad  112  is attachable to and detachable from the robot arm. The operation control unit  13  calculates a command speed (Pv) and a command angular velocity (φω) for controlling the position and the angle (orientation) of the conveyance hand, which is the base of the suction pad  112 , as a combination (simple sum) of the following two command values. The command angular velocity (φω) is a change speed of the angle of the conveyance hand. 
     1. A command speed Pv (more specifically, a command speed vector) for maintaining the contact between the suction pad  112  and the workpiece W at the contact point C. 
         Pv =( Pvr−Gv·ez ) h    
     Here, Pvr is the target speed of the suction pad  112 , Gv is a constant gain, ez is the Z-axis component of the normal vector R representing the inclination of the suction pad  112 , and h is the direction vector of the hand orientation (φ). Also, “·” represents multiplication. 
     2. Command speed (Pv) and command angular velocity (φω) for rotating suction pad  112  with contact point C as fulcrum 
     The contact point is set for an extended hand, and the position and the orientation of the contact point is set as {Pe, φe}. Because ex and ey are very small in step S 18 , it is assumed that φe=φ. {Pe, φe} is expressed as follows using the pad installation position offset (Po), the pad radius (Pr), θ that is obtained in step S 16 , and the original hand position and orientation {P, φ} in  FIG. 9 . 
       { Pe,φe}=FK ({ P,φe},{Po,Pr ,θ})
 
     Here, Pe is the center of rotation, Po is the offset of the suction pad installation position (the distance between the center of the suction surface of the suction pad  112  and the position of the conveyance hand), and Pr is the radius of the suction pad  112 . FK is a kinematics function for obtaining {Pe, φe} from {P, φ}. The inverse kinematics function IK corresponding to FK exists, and is set as follows. 
       { P,φ}=IK ({ Pe,φe},{Po,Pr ,θ})
 
     Assuming that Pe is the rotation center, and a command that gives rotation on a plane that passes through Pe and the central axis of the suction pad  112  is {Pev, φev}, the operation control unit  13  determines {Pv, φω} using the above IK or Jacobian derived from the IK. This set is defined as a command speed and a command angular velocity. 
     As described above, the operation control unit  13  changes the inclination of the suction pad  112  in accordance with the obtained command speed. Thereafter, the process proceeds to step S 20 . 
     Step S 20   
     In step S 20 , the operation control unit  13  determines whether or not the suction pad  112  and the workpiece W are entirely in contact with each other. More specifically, the operation control unit  13  performs the determination through the same process as that in step S 14  described above. If the operation control unit  13  determines that the suction surface of the suction pad  112  and the workpiece W are entirely in contact with each other (YES in step S 20 ), the operation control unit  13  completes the control of the inclination of the suction pad  112  and shifts to the control of the amount of pressing. If the operation control unit  13  does not determine that the suction surface of the suction pad  112  and the workpiece W are entirely in contact with each other (NO in step S 20 ), the process returns to step S 18 , and the operation control unit  13  continues to control the inclination of the suction pad  112 . 
     According to the above operation example, after the suction pad  112  has come into contact with the workpiece W, the operation control unit  13  specifies the position of the contact point C and the inclination of the suction pad  112 , and changes the inclination of the suction pad  112  to bring the suction pad  112  into intimate contact with the surface to be suctioned of the workpiece W while maintaining the contact at the contact point C. Therefore, the orientation of the suction pad  112  can be accurately corrected, and the workpiece W can be reliably picked up. 
     Operation Example 2 
       FIG. 11  is a flowchart showing the operation of a controller  5  in another embodiment of the present invention. Next, with reference to  FIG. 11 , an operation example in a case where the suction pad  112  presses the workpiece W before suctioning or placing an object will be described. 
     Step S 110   
     First, in step S 110 , the operation control unit  13  causes the suction pad  112  to approach the workpiece W by lowering the suction pad  112  in the vertical direction. 
     Step S 112   
     Next, in step S 112 , the operation control unit  13  determines whether or not the suction pad  112  has come into contact with the workpiece W, based on the amount of deformation of the suction pad  112 . 
     If the operation control unit  13  determines that the suction pad  112  has come into contact with the workpiece W based on the amount of deformation of the suction pad  112  (YES in step S 112 ), the process proceeds to step S 114 . If the operation control unit  13  does not determine that a part of the suction pad  112  has come into contact with the workpiece W (NO in step S 112 ), the process returns to step S 110  and the operation control unit  13  continues the approach of the suction pad  112  to the workpiece W. 
     Step S 114   
     Next, in step S 114 , the operation control unit  13  continues to press the suction pad  112  onto the workpiece W. At this time, the operation control unit  13  may also change the speed of the suction pad  112  in accordance with the deformation of the suction pad  112 . If the amount of deformation (amount of pressing ez) of the suction pad  112  exceeds a first threshold value, the operation control unit  13  may also reduce the speed at which the suction pad  112  is brought closer to the workpiece W. That is to say, the operation control unit  13  may also reduce the speed of the suction pad  112  in step S 114  with respect to the speed of the suction pad  112  in step S 110 . Thereafter, the process proceeds to step S 116 . 
     Step S 116   
     In step S 116 , the operation control unit  13  determines whether or not the pressing of the suction pad  112  onto the workpiece W is completed. In this step, letting the threshold value of the amount of pressing ez of the suction pad  112  against the workpiece W be ε 2 , the operation control unit  13  determines that the amount of pressing is sufficient if the following expression is satisfied, and otherwise does not determine that the amount of pressing is sufficient. 
         ez&gt;ε 2 
     Then, if the operation control unit  13  determines that the pressing of the suction pad  112  onto the workpiece W is completed (YES in step S 116 ), the operation control unit  13  stops the movement of the suction pad  112 . At this time, for example, if the amount of deformation of the suction pad  112  exceeds a second threshold value that is larger than the first threshold value, the operation control unit  13  may also stop the operation of bringing the suction pad  112  closer to the workpiece W. 
     When the pressing control is ended, the operation control unit  13  turns ON the vacuum pump  12  and starts suction of the object. If the deformation information obtaining unit  113  does not determine that the pressing of the suction pad  112  onto the workpiece W is completed (NO in step S 116 ), the process returns to step S 114  to continue the pressing. 
     In the above operation example, the deformation information obtaining unit  113  observes the amount of pressing of the suction pad  112  onto the workpiece W based on the amount of deformation of the suction pad  112 , and determines whether or not to continue the pressing. Therefore, because the amount of pressing ez onto the workpiece W can be kept within a certain range, the suction pad  112  can be pressed onto the workpiece W as appropriate when the workpiece W is picked up or placed. 
     Operation Example 3 
     Next, with reference to  FIG. 12 , an operation example when the suction pad  112  that is gripping the workpiece W places the workpiece W on the table will be described. 
     Step S 210   
     First, in step S 210 , the operation control unit  13  causes the suction pad  112  (the workpiece W) to approach the table by lowering the suction pad  112  in the vertical direction. 
     Step S 212   
     Next, in step S 212 , the operation control unit  13  determines whether or not a part of the workpiece W that is gripped by the suction pad  112  has come into contact with the table at the contact point C. Here, the operation control unit  13  basically performs the same process as the process in step S 12  in the operation example 1 described above. Due to the suction and the weight of the workpiece W, the amount of deformation {ex 0 , ey 0 , ez 0 } of the suction pad  112  before the workpiece W has come into contact with the table is not zero. The operation control unit  13  records the amount of deformation {ex 0 , ey 0 , ez 0 } of the suction pad  112  before the workpiece W has come into contact with the table. Then, if the following expression is satisfied, the operation control unit  13  determines that the workpiece W that is being gripped by the suction pad  112  is in contact with the table, and otherwise determines that the workpiece W is not in contact with the table. 
       |( ex−ex 0, ey−ey 0)|&gt;ε4, or | ez−ez 0|&gt;ε5
 
     If the operation control unit  13  determines that a part of the workpiece W (the surface that is not suctioned) is in contact with the table (YES in step S 212 ), the process proceeds to step S 214 . If the operation control unit  13  does not determine that a part of workpiece W is in contact with the table (NO in step S 212 ) at the contact point C, the process returns to step S 210 , and the operation control unit  13  continues to bring the workpiece W closer to the table. 
     Step S 214   
     Next, in step S 214 , the operation control unit  13  determines whether or not the lower surface of the workpiece W and the table are entirely in contact with each other. When the entire lower surface of the workpiece W has come into contact with the table, the inclination of the suction pad  112  and the workpiece W is eliminated, and thus the following expression is satisfied. 
       |( ex−ex 0, ey−ey 0)|&lt;ε4
 
     Therefore, the operation control unit  13  determines that the entire lower surface of the workpiece W is in contact with the table if the above expression is satisfied, and otherwise determines that the lower surface of the workpiece W is not in contact with the table. 
     If the operation control unit  13  determines that the lower surface of the workpiece W and table are entirely in contact with each other (YES in step S 214 ), the operation control unit  13  completes the inclination control of the suction pad  112 , and shifts to the control of the amount of pressing described above. If the operation control unit  13  does not determine that the workpiece W and the table are entirely in contact with each other (NO in step S 14 ), the process proceeds to step S 216 . 
     Step S 216   
     In step S 216 , the contact point specifying unit  131  specifies the position of the contact point C where the workpiece W contacts the surface of the table on which the workpiece W is to be placed, based on the deformation of the suction pad  112 . Here, the deformation information obtaining unit  113  performs basically the same process as that in step S 16  in the operation example 1. However, the deformation information obtaining unit  113  executes the following calculation using the recorded offset {ex 0 , ey 0 , ez 0 }. 
       θ=arctan(( ey−ey 0)/( ex−ex 0))
 
     When the contact point C where the workpiece W contacts the surface of the table on which the workpiece W is to be placed is specified by the above process, the process proceeds to step S 218 . 
     Step S 218   
     In step S 218 , the operation control unit  13  changes the inclination of the suction pad  112 , while maintaining the contact between the workpiece W and the surface of the table on which the workpiece W is to be placed at the specified contact point (contact side). At this time, the operation control unit  13  changes the inclination of the suction pad  112  to reduce the angle formed by the surface of the suctioned workpiece W, which is not the suctioned surface, and the surface of the table on which the workpiece W is to be placed. 
     Then, the operation control unit  13  basically performs the same process as that in step S 18  in the operation example 1 described above, and obtains a command speed for aligning the suction surface of the suction pad  112  to the surface of the table by changing the inclination of the workpiece W while maintaining the contact at the contact point. 
     However, the operation control unit  13  uses the recorded offset {ex 0 , ey 0 , ez 0 } to perform a calculation by reading the symbols as follows. 
     ez is read as ez−ez 0 .
 
{Pe,φe}: the contact point between the suction pad  112  and the workpiece W is read as the contact point between the workpiece W and the table.
 
{FK({P, φ}, {Po,Pr, θ}) is read as {FK({P, φ},{Po+Wh/2, Pr+Wl/2, θ})
 
     Here, Wh is the height of the workpiece W, Wl is the width of the workpiece W, and FK is the same kinematics function as FK in step S 18  in the operation example 1. 
     As a result, the expression in step S 18  in the operation example 1 is read as follows. 
     {P, φ}=IK({Pe, φe},{Po, Pr, θ}) is read as {P, φ}=IK({Pe, φe}, {Po+Wh/2, Pr+Wl/2, θ}) 
     Ik in the above expression is the same kinematics function as IK in step S 18  in the operation example 1. 
     In response to the above process, the operation control unit  13  changes the inclination of the suction pad  112  in accordance with the obtained command speed. Thereafter, the process proceeds to step S 220 . 
     Step S 220   
     Next, in step S 220 , the operation control unit  13  determines whether or not the surface of the workpiece W, which is not the suctioned surface, and the surface of the table on which the workpiece W is to be placed are entirely in contact with each other. At this time, the operation control unit  13  performs the same process as that in the step S 214  described above. 
     If the operation control unit  13  determines that the surface of the workpiece W, which is not the suctioned surface, and the surface of the table on which the workpiece W is to be placed are entirely in contact with each other (YES in step S 220 ), the operation control unit  13  completes the inclination control of the suction pad  112 , stops the suction, and releases the workpiece. If the operation control unit  13  does not determine that the surface of the workpiece W, which is not the suctioned surface, and the surface of the table on which the workpiece W is to be placed are entirely in contact with each other (NO in step S 220 ), the process returns to step S 218 , and the operation control unit  13  continues the inclination control of the suction pad  112 . 
     In the above operation example, the operation control unit  13  specifies the position of the contact point C and the inclination of the suction pad  112  after the surface of the workpiece W, which is not the suctioned surface, and the surface of the table on which the workpiece W is to be placed have come into contact with each other, and changes the inclination of the suction pad  112  so that the surface of the workpiece W, which is not the suctioned surface, and the surface of the table on which the workpiece W is to be placed are entirely in contact with each other while maintaining the contact at the contact point C. In this manner, the orientation of the suction pad  112  can be accurately corrected, and the workpiece W can be placed at an accurate position. Furthermore, it is possible to prevent an impact from being applied to the workpiece W released from the suction pad  112 , or prevent that workpiece W from falling over. 
     Operation Example 4 
     Next, with reference to  FIG. 13  and  FIGS. 14( a ) to 14( d ) , an operation example when the suction pad  112  that is gripping the workpiece W performs surface alignment of the side surface of the workpiece W with respect to the surface of the table on which the workpiece W is to be placed in a situation where the gravity direction is unclear will be described.  FIG. 13  is a flowchart showing a control frow of the controller  5  in this case, and  FIGS. 14( a ) to 14( d )  are side views illustrating states of the workpiece W that is gripped by the suction pad  112  and the table. 
     Step S 310   
     First, in step S 310 , the operation control unit  13  causes the suction pad  112  that is gripping the workpiece W to approach the surface of the table on which the workpiece W is to be placed ( FIG. 14( a ) ). 
     Step S 312   
     Next, in step S 312 , the operation control unit  13  determines whether or not a part of the side surface of the workpiece W that is gripped by the suction pad  112  has come into contact with the table at the contact point C, based on the amount of deformation of the suction pad  112 . At this time, the operation control unit  13  performs the same process as that in the step S 212  in the above operation example 3. If the operation control unit  13  determines that a part of the side surface of the workpiece W is in contact with the table (YES in step S 312 ), the process proceeds to step S 314  ( FIG. 14( b ) ). 
     If the operation control unit  13  does not determine that a part of the side surface of the workpiece W is in contact with the table (NO in step S 312 ), the process returns to step S 310 , and the operation control unit  13  continues to bring the workpiece W closer to the table. 
     Step S 314   
     Next, in step S 314 , the contact point specifying unit  131  specifies the position of the contact point (contact side) of the workpiece W with the surface of the table on which the workpiece W is to be placed, based on the deformation of the suction pad  112 . At this time, the operation control unit  13  performs the same process as that in the step S 216  in the above operation example 3. Then, the operation control unit  13  rotates the workpiece W around the contact point (contact side) toward the surface with which the workpiece W is to be brought into contact (surface of the table on which the workpiece W is to be placed) ( FIG. 14( c ) ). That is to say, the operation control unit  13  performs the same process as that in the step S 218  in the above operation example 3. Thereafter, the process proceeds to step S 316 . 
     Step S 316   
     Next, in step S 316 , the operation control unit  13  determines whether or not the side surface of the workpiece W and the table are entirely in contact with each other. More specifically, the operation control unit  13  performs the same process as that in the step S 212  in the operation example 3. If the deformation information obtaining unit  113  determines that the side surface of the workpiece W and the table are entirely in contact with each other (YES in step S 316 ,  FIG. 14( d ) ), the operation control unit  13  completes the control of inclination of the suction pad  112 , stops the suction, and releases the workpiece W. If the operation control unit  13  does not determine that the side surface of the workpiece W and the table are entirely in contact with each other (NO in step S 316 ), the process returns to step S 314 . 
     According to the operation example 4, even when the side surface of the workpiece W that is gripped by the suction pad  112  is to be aligned with the surface of the table on which the workpiece W is to be placed under the situation where the gravity direction is not clear, the operation control unit  13  specifies the position of the contact point and the inclination of the suction pad  112  after the side surface of the workpiece W and the surface of the table on which the workpiece W is to be placed have come into contact with each other at the contact point, based on the amount of deformation of the suction pad  112 . Thereafter, the operation control unit  13  changes the inclination of the suction pad  112  such that the side surface of the workpiece W to be brought into contact with the surface of the table on which the workpiece W is to be placed comes into contact with the surface of the table on which the workpiece W is to be placed, while maintaining the contact between the workpiece W and the surface of the table on which the object is to be placed at the contact point. As a result, the orientation of the suction pad  112  can be accurately corrected even in a situation where the gravity direction is not clear, and the side surface of the workpiece W can be aligned as appropriate. 
     Operation Example 5 
     Next, with reference to  FIG. 15  and  FIGS. 16( a ) to 16( c ) , an operation example will be described when the suction pad  112  that is gripping the workpiece W performs surface alignment of two side surface of the workpiece W with respect to two surfaces of the table in a situation where the gravity direction is not clear.  FIG. 15  is a flowchart showing a control frow of the controller  5  in this case, and  FIGS. 16( a ) to 16( c )  are side views illustrating states of the workpiece W that is gripped by the suction pad  112  and the table. 
     Step S 410   
     First, in step S 410 , the operation control unit  13  brings the suction pad  112  that is gripping the workpiece W closer to the surface on which the workpiece W is to be placed (vertical surface S 1 ). 
     Step S 412   
     Next, in step S 412 , the operation control unit  13  determines whether or not a part of the side surface of the workpiece W that is gripped by the suction pad  112  has come into contact with the first surface S 1  of the table at the contact side, based on the amount of deformation of the suction pad  112 . At this time, the operation control unit  13  performs the same process as that in the step S 212  in the above operation example 3. If the operation control unit  13  determines that a part of the side surface of the workpiece W is in contact with the surface S 1  of the table (YES in step S 412 ), the process proceeds to step S 414  ( FIG. 14( a ) ). 
     If the operation control unit  13  does not determine that a part of the side surface of the workpiece W is in contact with the table (NO in step S 412 ), the process returns to step S 410 , and the operation control unit  13  continues to bring the workpiece W closer to the table. 
     Step S 414   
     Next, in step S 414 , the contact point specifying unit  131  specifies the position of the contact side of the workpiece W with the surface S 1  of the table, based on the deformation of the suction pad  112 . At this time, the operation control unit  13  performs the same process as that in step S 216  in the operation example 3. Then, the operation control unit  13  rotates the workpiece W around the contact side toward the surface (surface S 3 ) of the table with which the workpiece W is to be brought into contact. In this case, the surface S 3  is a wall surface. Thereafter, the process proceeds to step S 416 . 
     Step S 416   
     Next, in step S 416 , the operation control unit  13  determines whether or not the side surface of the workpiece W and the surface S 3  of the table are entirely in contact with each other. At this time, the operation control unit  13  performs the same process as that in step S 214  in the operation example 3. If the operation control unit  13  determines that the side surface of the workpiece W and the surface S 3  of the table are entirely in contact with each other (YES in step S 416 ,  FIG. 14( b ) ), the process proceeds to step S 418 . If the operation control unit  13  does not determine that the side surface of the workpiece W and the surface S 3  of the table are entirely in contact with each other (NO in step S 416 ), the process returns to step S 414 . 
     Step S 418   
     Next, in step S 418 , the operation control unit  13  slides the workpiece W on the surface S 3  toward the horizontal surface (surface S 4 ) of the table, while maintaining the surface contact between the side surface of the workpiece W and the surface S 3  of the table. Thereafter, the process proceeds to step S 420 . 
     Step S 420   
     Next, in step S 420 , the operation control unit  13  determines whether or not the workpiece W has come into surface contact with the surface S 4 , which is the second surface. At this time, the operation control unit  13  performs the same process as that in step S 214  in the operation example 3. If the operation control unit  13  determines that the side surface of the workpiece W and the surface S 4  of the second surface of the table are entirely in contact with each other (YES in step S 420 ), the operation control unit  13  completes the surface alignment process ( FIG. 14( c ) ). If the operation control unit  13  does not determine that the side surface of the workpiece W and the surface S 4  of the table are in surface contact with each other (NO in step S 420 ), the process returns to step S 418 . 
     According to the operation example 5, even when the two outer surface of the workpiece W that is gripped by the suction pad  112  are aligned with the two inner surface of the table under the situation where the gravity direction is not clear, the operation control unit  13  can determine that the one surface of the workpiece W and the first surface of the table are completely aligned with each other based on the amount of deformation of the suction pad  112 , and then slide the workpiece W toward the second surface. As a result, even in a situation where the gravity direction is not clear, the orientation of the suction pad  112  can be accurately corrected, and the workpiece W can be accurately aligned with the two surfaces of the table. 
     In the above operation examples, the controller  5  of the present invention controls the operation of the suction pad  112  attached to the robot arm  11 . However, there is no limitation to this configuration, and the present invention can be applied to any suction pad. 
     While the embodiments of the present invention have been described in detail, the above description is merely illustrative of the present invention in every respect. Various modifications and variations can be made without departing from the scope of the invention. The following modifications are possible, for example. For convenience of description, the same reference numerals are used for the same members as those in the above-described embodiments, and the description of the same points as those in the above embodiments is omitted as appropriate. 
     Modified Example 
       FIG. 17  is a block diagram illustrating an example of a schematic configuration of a modified example of the suction apparatus  1  according to the present embodiment. In the example of  FIG. 17 , the controller  5  of the suction apparatus  1  includes an image processing unit  119  and a deformation information obtaining unit  113 , and the deformation information obtaining unit  113  includes a deformation amount change speed calculation unit  36  and a constant gain multiplication unit  37 . The deformation amount change speed calculation unit  36  may also be included in the image processing unit  119 , instead of the deformation information obtaining unit  113 . 
     The suction apparatus  1  including the controller  5  of the modified example includes a robot arm  11 , a vacuum pump (not shown), and the controller  5 . The robot arm  11  includes a suction pad  112 , an image capturing apparatus  121 , and a manipulator unit  111 . The image capturing apparatus  121  is fixedly disposed on the side of the suction pad  112 , and captures an image of a variable portion of the suction pad  112 . Due to the suction apparatus  1  including the image capturing apparatus  121 , the suction apparatus  1  can obtain the state of the variable portion of the suction pad  112  before and after deformation using the image or the like, and calculate the amount of deformation of the suction pad  112  based on the obtained data. 
     The controller  5  includes an image processing unit  119 , a deformation information obtaining unit  113 , and an operation control unit  13 . The image processing unit  119  includes an image obtaining unit  120 , a feature point specifying unit  123 , and a deformation amount specifying unit  124 . 
     The image capturing apparatus  121  captures an image of the variable portion of the suction pad  112 . The image data may be monochrome image data, or may also be color image data. 
     The image obtaining unit  120  obtains image data captured by the image capturing apparatus  121 . Then, the image obtaining unit  120  inputs the obtained image data to the feature point specifying unit  123 . 
     The feature point specifying unit  123  specifies the feature point of the variable portion included in the image data that is received from the image obtaining unit  120 . The feature point specifying unit  123  specifies feature points in the image data corresponding to the plurality portions of the variable portion  118 , based on the pattern formed on the variable portion, which is included in the received image data. Then, the feature point specifying unit  123  outputs, to the deformation amount specifying unit  124 , the coordinate values of the feature points in the image coordinate system. The feature point specifying unit  123  also specifies the coordinates (a plurality of coordinates) of the fixed portions, which are not deformed, of the suction pad  112 , as the reference coordinates. The displacement of the respective feature points can be obtained, based on the coordinates of the feature points relative to the reference coordinates. 
     The deformation amount specifying unit  124  specifies the amounts of deformation of the plurality of portions of the variable portion (that is to say, the amount of deformation of the suction pad  112 ), based on the feature points (coordinate values) and the coordinates of the fixed portions that are output from the feature point specifying unit  123 . 
     The deformation amount change speed calculation unit  36  calculates the change speed of the amount of deformation, by time-differentiating the amount of deformation that is specified by the deformation amount specifying unit  124 . Then, the deformation amount change speed calculation unit  36  outputs the change speed of the amount of deformation to the constant gain multiplication unit  37 . 
     The constant gain multiplication unit  37  calculates a deceleration value, by multiplying the change speed of the amount of deformation (the angular velocity of the suction surface of the suction pad, for example), which is calculated by the deformation amount change speed calculation unit  36 , by a constant. The constant gain multiplication unit  37  outputs the calculated deceleration value to the operation control unit  13 . 
     The operation control unit  13  stores a target moving speed of the suction pad  112  for conveying the object. The operation control unit  13  obtains the command speed, by subtracting the deceleration value from the target moving speed. The operation control unit  13  controls the manipulator unit  111  to move the hand (suction pad  112 ) of the manipulator at the command speed. By changing the speed of the hand of the robot arm to reduce the change speed of the amount of deformation of the suction pad  112 , vibration of the suction pad  112  (vibration of the object) can be reduced. 
     Similarly, the operation control unit  13  may also change the inclination of the suction pad  112  to decrease the change speed of the amount of deformation, based on the change speed of the amount of deformation. By changing the inclination of the suction pad  112 , the vibration of the suction pad  112  can be controlled. In addition, by utilizing the inclination of the suction pad  112  for vibration damping control, the positioning time at the time of stopping conveyance can be minimized, and the conveyance processing time (conveyance tact time) can be shortened. 
       FIG. 18  is a flowchart showing an example of a process flow in a modified example 3 of the deformation measuring apparatus according to the present embodiment. 
     In step S 501 , the operation control unit  13  brings the suction pad  112  closer to the object W. The example of  FIG. 19( a )  shows the process in step S 501 . Next, in step S 502 , the operation control unit  13  determines whether or not the suction pad  112  is in contact with the object W. Whether or not the suction pad  112  is in contact with the object W can be determined by the amount of deformation of the variable portion of the suction pad  112 . If the amount of deformation is larger than or equal to a threshold value, the operation control unit  13  determines that the suction pad  112  is in contact with the object W. If the operation control unit  13  determines that the suction pad  112  is in contact with the object W (YES in step S 502 ), the operation control unit  13  causes the suction pad  112  to suction the object W (step S 503 ). The example of  FIG. 19( b )  shows the process in step S 503 . If the operation control unit  112  determines that the suction pad  112  is not in contact with the object W (NO in step S 502 ), the operation control unit  13  executes the processes of step S 501  and step S 502  again. 
     In step S 504 , the operation control unit  13  causes the manipulator unit  111  to lift the object W. The example of  FIG. 19( c )  shows the process in step S 504 . Next, in step S 505 , the operation control unit  13  determines whether or not the lifting of the object W has succeeded. Whether or not the object W has been successfully lifted can be determined by the amount of deformation of the variable portion of the suction pad  112 . If the amount of deformation is larger than or equal to another threshold value, the operation control unit  13  determines that the lifting of the object W has succeeded. If the operation control unit  13  determines that the lifting of the object W has succeeded (YES in step S 505 ), the object W is conveyed to the target position (step S 506 ). The example of  FIG. 19( d )  shows the process in step S 506 . If the operation control unit  13  determines that the lifting of the object W has failed (NO in step S 505 ), the operation control unit  13  executes the processes of steps S 504  and step S 505  again. 
     In step S 507 , the operation control unit  13  determines whether or not vibration occurs in the suction pad  112  that is conveying the object W. If the change speed of the amount of deformation of the suction pad  112  is larger than or equal to still another threshold value, the operation control unit  13  determines that the vibration is occurring on the suction pad  112  that is conveying the object W. If the operation control unit  13  determines that no vibration is occurring in the suction pad  112  that is conveying the object W (YES in step S 507 ), the object W is conveyed to the target position without changing the inclination of the object W (step S 508 ). If the operation control unit  13  determines that the vibration is occurring in the suction pad  112  that is conveying the object W (YES in step S 507 ), the operation control unit  13  controls the inclination of the suction pad  112  (step S 512 ). Then, the operation control unit  13  executes the process in step S 507  again. 
     In step S 209 , the operation control unit  13  causes the manipulator unit  111  to lower the object W to the target position. The example of  FIG. 19( e )  shows the process in step S 209 . Next, in step S 510 , the operation control unit  13  determines whether or not the object W has come into contact with the target position. Whether or not the object W has come into contact with the target position can be determined by the amount of deformation of the variable portion of the suction pad  112 . If the amount of deformation is larger than or equal to still another threshold value, the operation control unit  13  determines that the object W has come into contact with the target position. If the operation control unit  13  determines that the object W has come into contact with the target position (YES in step S 510 ), the operation control unit  13  releases the suction of the suction pad  112  (step S 511 ). The example of  FIG. 19( f )  shows a case in which the determination of the process in step S 510  is YES. If the operation control unit  13  determines that the object W has not come into contact with the target position (NO in step S 510 ), the operation control unit  13  executes the processes of step S 509  and step S 510  again. Implementation example using software 
     The functions of the control blocks of the mobile suction apparatus  100  (in particular, the units of the controller  5 : the negative pressure control unit  21 ; the deformation information obtaining unit  113 ; and the operation control unit  13 , and the abnormality determination unit  115 ) may also be achieved by a logic circuit (hardware) that is formed on an integrated circuit (IC chip) or the like, or may also be achieved by software. 
     In the latter case, the mobile suction apparatus  100  includes a computer that executes instructions of a program, which is software for achieving the functions. This computer includes, for example, one or more processers and a computer-readable recording medium storing the program. Then, due to the processor of the computer reading the program from the recording medium and executing the program, the object of the present invention is achieved. As the processor, for example, a central processing unit (CPU) can be used. Examples of the recording medium include a “non-transitory tangible medium” such as a read only memory (ROM), a tape, a disk, a card, a semiconductor memory, and a programmable logic circuit. In addition, a random access memory (RAM) or the like for developing the program may also be further provided. Furthermore, the program may also be supplied to the computer via any transmission medium (a communication network, a broadcast wave, or the like) capable of transmitting the program. Note, that the embodiment of the present invention can also be achieved in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission. 
     For the present invention, there is no limitation to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each of the embodiments. 
     INDEX TO THE REFERENCE NUMERALS 
     
         
         
           
               1  Suction apparatus 
               100  Mobile suction apparatus 
               2  Conveyance unit 
               3  Battery 
               5  Controller 
               11  Robot arm 
               12  Vacuum pump 
               13  Manipulator control unit (operation control unit) 
               14  Object information obtaining unit 
               15  Placement information obtaining unit 
               21  Negative pressure control unit 
               22  Automated guided vehicle 
               111  Manipulator unit 
               113  Deformation information obtaining unit 
               112  Suction portion (suction pad) 
               119  Image processing unit 
               120  Image obtaining unit 
               121  Image capturing apparatus 
               123  Feature point specifying unit 
               124  Deformation amount specifying unit 
               131  Contact point specifying unit 
               114  Sensor 
               115  Abnormality determination unit 
               211  Analog signal output unit 
               221  Conveyance control unit