Patent Publication Number: US-2023142013-A1

Title: Cargo handling apparatus, control device, cargo handling method, and storage medium

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-183548, filed on Nov. 10, 2021; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a cargo handling apparatus, a control device, a cargo handling method, and a storage medium. 
     BACKGROUND 
     There is a cargo handling apparatus that performs cargo handling tasks. Cargo handling apparatus technology that can more efficiently perform cargo handling tasks is desirable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view schematically showing a cargo handling apparatus according to an embodiment; 
         FIGS.  2 A to  2 C  are schematic views showing a first operation of the cargo handling apparatus according to the embodiment; 
         FIGS.  3 A and  3 B  are schematic views showing the first operation of the cargo handling apparatus according to the embodiment; 
         FIGS.  4 A and  4 B  are schematic views showing a second operation of the cargo handling apparatus according to the embodiment; 
         FIG.  5    is a schematic view showing a function of the control device of the cargo handling apparatus according to the embodiment; 
         FIGS.  6 A to  6 C  are schematic views showing operations of the cargo handling apparatus corresponding to the control of the start timing; 
         FIGS.  7 A and  7 B  are schematic views showing operations of the cargo handling apparatus corresponding to the control of the start timing; 
         FIGS.  8 A and  8 B  are schematic views for describing the determination method of the interference; 
         FIG.  9    is a schematic view showing a function of a control device of a cargo handling apparatus according to a first modification of the embodiment; 
         FIGS.  10 A and  10 B  are schematic views showing an operation of the cargo handling apparatus according to the first modification of the embodiment; 
         FIGS.  11 A and  11 B  are schematic views showing an operation of the cargo handling apparatus according to the first modification of the embodiment; 
         FIGS.  12 A to  12 C  a are schematic views showing another operation of the cargo handling apparatus according to the embodiment; 
         FIGS.  13 A to  13 C  are schematic views showing another operation of the cargo handling apparatus according to the embodiment; 
         FIG.  14    is a schematic view showing a function of a control device of a cargo handling apparatus according to the second modification of the embodiment; 
         FIGS.  15 A and  15 B  are schematic views showing an operation of the cargo handling apparatus according to the second modification of the embodiment; 
         FIGS.  16 A and  16 B  are schematic views showing an operation of the cargo handling apparatus according to the second modification of the embodiment; 
         FIG.  17    is a schematic view showing a hardware configuration. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a cargo handling apparatus includes a hand, a robot arm, a transfer device, a measurement device, and a control device. The hand holds an article. The robot arm moves the hand. The transfer device is arranged with the robot arm in a first direction, and transfers the article. The measurement device measures a position and a size of the article. The control device performs a first operation of transferring the article to the transfer device by using the hand and the robot arm, and a second operation of transferring the transferred article by using the transfer device. The control device determines, based on a measurement result of the measurement device, whether or not the robot arm will interfere with the transfer device or a second article on the transfer device when performing the first operation for a first article. The control device controls a start timing of the first operation according to a determination result of the interference. 
     Various embodiments are described below with reference to the accompanying drawings. 
     The drawings are schematic and conceptual; and the relationships between the thickness and width of portions, the proportions of sizes among portions, etc., are not necessarily the same as the actual values. The dimensions and proportions may be illustrated differently among drawings, even for identical portions. 
     In the specification and drawings, components similar to those described previously or illustrated in an antecedent drawing are marked with like reference numerals, and a detailed description is omitted as appropriate. 
       FIG.  1    is a perspective view schematically showing a cargo handling apparatus according to an embodiment. 
     The cargo handling apparatus  100  according to the embodiment is installed in a site where cargo handling tasks of articles are performed. For example, cargo handling tasks include unloading and loading. As an example, a transfer device C that transfers an article A is installed next to the cargo handling apparatus  100 . The transfer device C is, for example, a belt conveyor, a roller conveyor, a chain conveyor, etc. Also, a pallet P on which the article A is loaded is placed next to the cargo handling apparatus  100 . The cargo handling apparatus  100  is positioned between the transfer device C and the pallet P. The cargo handling apparatus  100  moves the article A placed on the pallet P to the transfer device C. 
     As shown in  FIG.  1   , the cargo handling apparatus  100  includes a support frame  110 , a hand  120 , a robot arm  130 , a measurement device  140 , a negative-pressure generation device  150 , a transfer device  160 , a moving device  170 , a moving device  180 , and a control device  190 . 
     Herein, an XYZ coordinate system is used in the description. An X-direction (a second direction) and a Y-direction (a third direction) cross each other. A Z-direction (a first direction) crosses the X-Y plane (a first plane). For example, the Z-direction is parallel to the vertical direction; and the X-direction, the Y-direction, and the Z-direction are orthogonal to each other. 
     The support frame  110  supports the components of the cargo handling apparatus  100 . The hand  120  can hold an article. The robot arm  130  moves the hand  120  along the X-Y plane. The measurement device  140  recognizes the article and measures the position and size of the article. The transfer device  160  transfers the article A transferred by the hand  120  and the robot arm  130  toward the transfer device C. The moving device  170  moves the robot arm  130  in the Z-direction. The moving device  180  moves the transfer device  160  in the Z-direction. The control device  190  controls the operations of the components of the cargo handling apparatus  100 . 
     One specific example of the components will now be elaborated. 
     The support frame  110  forms the contour of the cargo handling apparatus  100  and is fixed to the floor surface. The support frame  110  includes a main part  111  and a protruding part  112 . The main part  111  has a rectangular parallelepiped shape. The transfer device  160  is located inside the main part  111 . The main part  111  has an opening  113  facing the pallet P side and an opening  114  facing the transfer device C side. The article A is transferred from the pallet P to the transfer device  160  via the opening  113 . Also, the article A is transferred from the transfer device  160  to the transfer device C via the opening  114 . 
     The main part  111  includes, for example, four vertical frames  111   a  and multiple horizontal frames  111   b  that link the upper ends of the four vertical frames  111   a  to each other and the lower ends of the four vertical frames  111   a  to each other. The protruding part  112  is mounted frontward of the upper portion of the main part  111  and protrudes frontward. The protruding part  112  is positioned above the pallet P. 
     The hand  120  holds (stably grips) the article by suction-gripping, pinching, or jamming. In the illustrated example, the hand  120  includes an upper surface suction-gripping unit  121  (a first suction-gripping unit) and a side surface suction-gripping unit  122  (a second suction-gripping unit) for suction-gripping the article. 
     The robot arm  130  is an orthogonal robot. The robot arm  130  includes a first linear unit  131  and a second linear unit  132 . The first linear unit  131  is linked to the hand  120  and can extend and retract or slide along the X-direction. The hand  120  can be moved along the X-direction by the operation of the first linear unit  131 . The second linear unit  132  extends along the Y-direction and movably supports the first linear unit  131  from below. The second linear unit  132  moves the first linear unit  131  along the Y-direction. The hand  120  can be moved along the Y-direction by the operation of the second linear unit  132 . The first linear unit  131  and the second linear unit  132  are operated by actuators such as motors, air cylinders, etc. 
     The robot arm  130  is not limited to the illustrated example and may be a vertical articulated robot, a horizontal articulated robot, a linear robot, or a parallel link robot. The robot arm  130  may include a combination of at least two selected from a vertical articulated robot, a horizontal articulated robot, a linear robot, an orthogonal robot, and a parallel link robot. 
     The measurement device  140  includes a first measuring instrument  141 , a second measuring instrument  142 , and a third measuring instrument  143 . The article that is placed on the pallet P is measured by the first measuring instrument  141  in the Z-direction. The article is measured by the second measuring instrument  142  in a direction crossing the Z-direction. The third measuring instrument  143  measures the Z-direction position of the bottom surface of the transferred article. 
     Specifically, the first measuring instrument  141  includes an imaging part  141   a.  The imaging part  141   a  is fixed to a support part  112   a  included in the protruding part  112 . The imaging part  141   a  includes one or two selected from an image sensor and a distance sensor. The article A that is placed on the pallet P is imaged from above by the imaging part  141   a.  The imaging part  141   a  transmits the acquired image (still image) to the control device  190 . The imaging part  141   a  may acquire a video image. In such a case, a still image is cut out from the video image. 
     The control device  190  calculates data related to the article based on the image acquired by the imaging part  141   a.  The calculated data includes the recognition result of the upper surface of the article A in the image, the position of the upper surface in the X-direction, the Y-direction, and the Z-direction, the X-direction length of the upper surface, the Y-direction length of the upper surface, the surface area of the upper surface, etc. The imaging part  141   a  and the control device  190  function as the first measuring instrument  141 . An image recognition system other than the control device  190  may be embedded in the imaging part  141   a  and used as the first measuring instrument  141 . 
     The second measuring instrument  142  includes a distance sensor  142   a.  The distance sensor  142   a  measures the distance to the article in a direction crossing the Z-direction. In the illustrated example, the second measuring instrument  142  is located at one of the multiple vertical frames  111   a  and measures the distance to the article in a direction that is perpendicular to the Z-direction and oblique to the X-direction and the Y-direction. The distance sensor  142   a  emits an infrared ray, laser light, or an ultrasonic wave toward the article. From the perspective of the measurement accuracy of the distance, it is favorable for the distance sensor  142   a  to be a laser rangefinder (LRF) using laser light. Based on the measurement result of the distance sensor  142   a,  the control device  190  calculates the recognition result of the side surface of the article A, the position in the X-Y plane of the side surface of the article A, etc. The distance sensor  142   a  and the control device  190  function as the second measuring instrument  142 . 
     The second measuring instrument  142  may include a moving device  142   b.  The moving device  142   b  moves the distance sensor  142   a  along the Z-direction. In such a case, the control device  190  can measure the positions of the upper surfaces of the articles in the Z-direction, the positions of the lower surfaces of the articles in the Z-direction, the levels (the Z-direction positions) of the articles, etc., based on the measurement result of the distance sensor  142   a  and the movement amount of the moving device  142   b.    
     Similarly to the first measuring instrument  141 , the second measuring instrument  142  may include an imaging part. The article A that is placed on the pallet P is imaged from the side by the imaging part. The imaging part transmits the acquired image to the control device  190 . The control device  190  calculates the recognition result of the side surface of the article A, the position in the X-Y plane of the side surface of the article A, the height of the article A, etc., based on the image. In such a case, the imaging part and the control device  190  function as the second measuring instrument  142 . 
     The third measuring instrument  143  includes a distance sensor  143   a  installed between the main part  111  and the pallet P. The distance sensor  143   a  measures the distance to the bottom surface of the article A passing above the distance sensor  143   a.  The control device  190  measures the Z-direction position of the bottom surface of the article A based on the measurement result of the distance sensor  143   a.  Favorably, the distance sensor  143   a  is a LRF using laser light. The distance sensor  143   a  and the control device  190  function as the third measuring instrument  143 . 
     Similarly to the first measuring instrument  141 , the third measuring instrument  143  may include an imaging part. The imaging part is installed between the main part  111  and the pallet P and images, from below, the article A passing above the imaging part. The imaging part transmits the acquired image to the control device  190 . The control device  190  calculates the Z-direction position of the bottom surface of the article A based on the image. In such a case, the imaging part and the control device  190  function as the third measuring instrument  143 . 
     The negative-pressure generation device  150  can individually adjust the pressure of the upper surface suction-gripping unit  121  and the pressure of the side surface suction-gripping unit  122 . The negative-pressure generation device  150  includes multiple pipes  151  connected to the upper surface suction-gripping unit  121  and the side surface suction-gripping unit  122 . The negative-pressure generation device  150  also includes a not-illustrated vacuum pump, ejectors, valves, etc. 
     The transfer device  160  is, for example, a belt conveyor. The transfer device  160  includes a belt  161 , pulleys  162 , and a driver  163 . The belt  161  is an endless belt threaded over a pair of the pulleys  162  separated from each other in the X-direction. One end of the belt  161  is next to the transfer device C. The rotation axes of the pulleys  162  are parallel to the Y-direction. The driver  163  drives the belt  161  by rotating one of the pair of pulleys  162 . The article A that is placed on the transfer device  160  is transferred toward the transfer device C by the driving of the belt  161 . Other than the illustrated example, the transfer device  160  may be a roller conveyor, a chain conveyor, etc. 
     The moving device  170  moves the robot arm  130  along the Z-direction. The moving device  170  includes a driver  171 , a shaft  172 , and a wire  173 . The driver  171  is mounted to the upper end of the main part  111 . The shaft  172  extends along the Y-direction and is linked to the driver  171 . The wire  173  is wound around the shaft  172 . One end of the wire  173  is linked to the robot arm  130 . The driver  171  rotates the shaft  172 . The robot arm  130  is moved along the Z-direction according to the rotation of the shaft  172  by the wire  173  winding or unwinding. 
     Here, in the example of the description, the moving device  170  is located separately from the robot arm  130 . The moving device  170  may be included in the robot arm  130  as an axis for providing a Z-direction degree of freedom. 
     The moving device  180  includes a driver  181 , a shaft  182 , and a wire  183 . The driver  181  is mounted to the upper end of the main part  111 . The shaft  182  extends along the Y-direction and is linked to the driver  181 . The wire  183  is wound around the shaft  182 . One end of the wire  183  is linked to the transfer device  160 . The driver  181  rotates the shaft  182 . The transfer device  160  is moved along the Z-direction according to the rotation of the shaft  182  by the wire  183  winding or unwinding. 
     The control device  190  is electrically connected with the hand  120 , the imaging part  141   a,  the distance sensor  142   a,  the distance sensor  143   a,  the negative-pressure generation device  150 , the driver  163 , the driver  171 , and the driver  181 . The control device  190  controls the hand  120 , the negative-pressure generation device  150 , the driver  163 , the driver  171 , the driver  181 , etc., based on the measurement result of the first measuring instrument  141 , the measurement result of the second measuring instrument  142 , and the measurement result of the third measuring instrument  143 . 
     The cargo handling apparatus  100  performs a first operation and a second operation. In the first operation, the cargo handling apparatus  100  transfers the article A to the transfer device  160  by using the hand  120  and the robot arm  130 . In the second operation, the article A that is transferred onto the transfer device  160  is transferred toward the transfer device C by the transfer device  160 . 
       FIGS.  2 A to  2 C ,  FIG.  3 A , and  FIG.  3 B  are schematic views showing the first operation of the cargo handling apparatus according to the embodiment.  FIGS.  4 A and  4 B  are schematic views showing the second operation of the cargo handling apparatus according to the embodiment. Here, in the example of the description, the article is held by the hand  120  using only the upper surface suction-gripping unit  121 . The side surface suction-gripping unit  122  is not illustrated in  FIG.  2 B  and subsequent drawings. 
     For example, the article that has the upper surface at the highest position among the multiple articles placed on the pallet P is determined to be the holding object. When multiple articles have upper surfaces at the highest position, the article that is most proximate to the distance sensor  142   a  is determined to be the holding object. 
     As shown in  FIG.  2 A , the upper surface suction-gripping unit  121  includes multiple suction-gripping parts  121   a.  Each suction-gripping part  121   a  includes a rod  121   b  extending in the Z-direction and a pad  121   c  located at the tip of the rod  121   b.  The pad  121   c  is elastic to be deformable along the upper surface of the article. Similarly, the side surface suction-gripping unit  122  includes multiple suction-gripping parts  122   a.  Each suction-gripping part  122   a  includes a rod  122   b  extending in the X-direction and a pad  122   c  located at the tip of the rod  122   b.  The pad  122   c  is elastic to be deformable along the side surface of the article. 
     First, as shown in  FIG.  2 A , the robot arm  130  causes the hand  120  to lift the article A determined to be the holding object. For example, the side surface suction-gripping unit  122  is positioned backward of the upper surface suction-gripping unit  121 . The moving device  170  lowers the hand  120  toward the article A. As shown in  FIG.  2 B , the upper surface suction-gripping unit  121  suction-grips the upper surface of the article A. At this time, the distance sensor  142   a  is positioned higher than the article that is held. As shown in  FIG.  2 C , the moving device  170  raises the hand  120  and the robot arm  130 . The article A is raised thereby. 
     While raising the article A, the distance sensor  142   a  continues to measure the distance to the article that is held. The measured distance changes when the upper surface of the article A passes through the level of the distance sensor  142   a  and when the bottom surface of the article A passes through the level of the distance sensor  142   a.  The control device  190  measures the height of the article A that is held based on the change. The moving device  142   b  may lower the distance sensor  142   a  while raising the article A. The height of the article A can be more quickly measured by moving the distance sensor  142   a  in the direction opposite to the movement direction of the article. 
     As shown in  FIG.  3 A , the robot arm  130  moves the hand  120  above the transfer device  160 . At this time, the distance sensor  143   a  measures the distance to the bottom surface of the article A that is held. As shown in  FIG.  3 B , the moving device  170  lowers the hand  120  toward the transfer device  160  and places the article A that is held on the transfer device  160 . 
     As shown in  FIG.  4 A , the hand  120  releases the holding of the article A. The moving device  170  shown in  FIG.  1    raises the hand  120  and the robot arm  130 . After raising the hand  120  and the robot arm  130 , the moving device  180  shown in  FIG.  1    raises the transfer device  160  and sets the Z-direction position of the transfer device  160  to be the same position as the transfer device C. As shown in  FIG.  4 B , the transfer device  160  transfers the article A that is transferred to the transfer device C. The raising of the transfer device  160  may be performed while transferring the article A. The start timing of the second operation can be accelerated thereby. 
     For example, the cargo handling task (the first operation and the second operation) is repeated until all of the articles A on the pallet P are transferred to the transfer device C. For example, the first operation and the second operation are alternately repeated. The next first operation is performed after completing one second operation. To increase the efficiency of the cargo handling task, it is favorable to perform at least a portion of the first operation of the next article in parallel with the second operation of the previous article. On the other hand, the robot arm  130  and the transfer device  160  of the cargo handling apparatus  100  are arranged in the vertical direction to downsize the cargo handling apparatus  100 . The transfer device  160  is positioned below the robot arm  130 . Therefore, there is a possibility that the robot arm  130  may interfere with the transfer device  160  when the first operation is performed in parallel with the second operation. 
     “Interference” is, for example, contact of the robot arm  130  with another object. “Interference” may include the distance between the robot arm  130  and the other object falling below a margin set for safety. 
     For the problems described above, the control device  190  determines, based on the measurement result of the measurement device  140 , whether or not the robot arm  130  will interfere with the transfer device  160  or another article (a second article) on the transfer device  160  when performing the first operation of one article (a first article). Then, the control device  190  controls the start timing of the first operation according to the determination result of the interference. For example, when the interference will not occur, the control device  190  accelerates the start timing of the first operation for the first article compared to when the interference will occur. 
       FIG.  5    is a schematic view showing a function of the control device of the cargo handling apparatus according to the embodiment. 
     A method for controlling the start timing of the first operation will now be described with reference to  FIG.  5   . The control device  190  functions as a task managing part  191 , a planning part  192 , and an operation controller  193 . 
     The task managing part  191  manages general tasks of the cargo handling task. The task managing part  191  requests the planning part  192  to generate a plan related to the cargo handling task. Also, the task managing part  191  requests the operation controller  193  to control the operation of the cargo handling apparatus  100  for the cargo handling task. 
     The planning part  192  causes the first measuring instrument  141  and the second measuring instrument  142  to measure the article placed on the pallet (step S 1 ). The planning part  192  acquires the position of the upper surface of the article, the shape of the upper surface of the article, the position of the side surface of the article, etc., from the measurement. The planning part  192  generates a plan based on the measurement result (step S 2 ). The plan includes the article that is held, the position of the article held by the hand  120 , the operation path of the robot arm  130 , etc. The operation path includes the path to the holding position and the path from the holding position to the transfer device  160  when transferring the article. 
     The planning part  192  determines whether or not the robot arm  130  will interfere with the transfer device  160  or the article on the transfer device  160  when the robot arm  130  operates along the operation path or when the hand  120  is at the holding position (step S 3 ). When determining the interference, the transfer device  160  is assumed to be at the same level as the transfer device C. The planning part  192  stores the plan and the determination result of the interference (step S 4 ). 
     The operation controller  193  confirms the plan and the interference determination result stored by the planning part  192  according to a request from the task managing part  191  (step S 11 ). The operation controller  193  determines whether or not interference of the robot arm  130  with the transfer device  160  or the article on the transfer device  160  is determined to occur in the interference determination result (step S 12 ). Thereafter, the determination that the determination result of the operation controller  193  determines interference to occur in the interference determination result also is called simply “interference occurs” or “interferes”. The determination that the interference determination result determines interference not to occur also is called simply “interference does not occur” or “does not interfere”. When interference will occur, the operation controller  193  determines whether or not the previous article on the transfer device  160  has been transferred by the transfer device  160  (step S 13 ). The “previous article” is the article transferred to the transfer device  160  by the first operation before the first operation for the article for which holding is planned. When the previous article has not yet been transferred from the transfer device  160 , the operation controller  193  causes the robot arm  130  to standby until the previous article is transferred from the transfer device  160 . 
     When interference will not occur, the operation controller  193  moves the hand  120  by operating the robot arm  130  (step S 14 ). The robot arm  130  moves along the planned operation path. The hand  120  moves to the planned holding position. The first operation is started when the hand  120  is moved to the holding position. In other words, the target article is held and transferred to the transfer device  160 . In the first operation, the operation controller  193  causes the second measuring instrument  142  to measure the height of the article that is held (step S 15 ). The operation controller  193  stores the height of the measured article (step S 16 ). The stored height is utilized when determining the interference related to the next article. 
       FIGS.  6 A to  6 C ,  FIG.  7 A , and  FIG.  7 B  are schematic views showing operations of the cargo handling apparatus corresponding to the control of the start timing. 
     For example, in the state shown in  FIG.  6 A , an article A 1  (an example of the first article) is determined to be the holding object. An article A 2  (an example of the second article) is transferred by the transfer device  160 . The upper surface of the article A 1  is positioned lower than the upper surface of the article A 2 . The robot arm  130  interferes with the article A 2  when the hand  120  holds the article A 1 . Therefore, interference is determined to occur in steps S 3  and S 12 . In such a case, as shown in  FIG.  6 B , the robot arm  130  and the moving device  170  do not operate until the article A 2  is transferred by the transfer device  160 . As shown in  FIG.  6 C , the robot arm  130  moves after the transfer device  160  transfers the article A 2  and is lowered. In other words, the first operation for the article A 1  is not started until the second operation for the article A 2  is completed. 
     On the other hand, for example, in the state shown in  FIG.  7 A , an article A 3  (an example of the first article) is determined to be the holding object. An article A 4  (an example of the second article) is transferred by the transfer device  160 . The article A 3  is positioned higher than the article A 4 . The robot arm  130  does not interfere with the article A 4  even when the hand  120  holds the article A 3 . Therefore, interference is determined not to occur in steps S 3  and S 12 . In such a case, as shown in  FIG.  7 B , the robot arm  130  and the moving device  170  operate while the transfer device  160  transfers the article A 4 . In other words, the start timing of the first operation is earlier than the example shown in  FIGS.  6 A to  6 C . As a result, the first operation for the article A 3  is started while performing the second operation for the article A 4 . At least a portion of the first operation is performed in parallel with the second operation. 
     Advantages of the embodiment will now be described. 
     In the cargo handling apparatus  100  as described above, the start timing of the first operation is controlled according to the existence or absence of the interference of the robot arm  130  when performing the first operation. For example, when the interference of the robot arm  130  will not occur, the start timing of the first operation is earlier than when the interference of the robot arm  130  will occur. According to the embodiment, the efficiency of the cargo handling task of the cargo handling apparatus  100  can be further improved even when the cargo handling apparatus  100  is downsized by providing the transfer device  160  below the robot arm  130 . 
     In the example shown in  FIGS.  7 A and  7 B , it is unnecessary to lower the transfer device  160  to avoid interference with the robot arm  130 . The time necessary to move the transfer device  160  can be reduced by omitting the lowering of the transfer device  160  and the raising of the transfer device  160  to the same level as the transfer device C; and the cargo handling task can have even higher efficiency. 
       FIGS.  8 A and  8 B  are schematic views for describing the determination method of the interference. 
     For example, as shown in  FIG.  8 A , the planning part  192  sets a virtual minimum rectangle R surrounding the robot arm  130  in the X-Z plane. The sides of the rectangle R are set to be parallel to the X-direction or the Z-direction. For example, the minimum rectangle R that circumscribes the robot arm  130  is set in the X-Z plane. The planning part  192  simply determines whether or not the robot arm  130  interferes with the transfer device  160  or the article on the transfer device  160  by determining whether or not the rectangle R interferes with the transfer device  160  or the article on the transfer device  160 . According to this method, the calculation amount necessary for determining the interference can be reduced. For example, the end timing of the calculation by the planning part  192  can be earlier, and the processing by the operation controller  193  can be started earlier. As a result, the efficiency of the cargo handling task of the cargo handling apparatus  100  can be further improved. 
     A height H of the article used in the determination of the interference is based on the measurement result of the second measuring instrument  142 . As described above, the distance sensor  142   a  measures the height H while the moving device  170  moves the article. By moving the distance sensor  142   a  in the direction opposite to the movement direction of the article, the height H of the article A can be more quickly measured. The start timing of the determination of the interference can be accelerated thereby. The end timing of the calculation by the planning part  192  can be earlier, and the processing by the operation controller  193  can be started earlier. 
     As shown in  FIG.  8 B , it may be determined whether or not the components of the robot arm  130  interfere with the transfer device  160  or the article on the transfer device  160  in the X-Z plane. For example, the control device  190  determines whether or not interference will occur for the components of the robot arm  130  by calculating a distance D 1  between the article A and the first linear unit  131  of the robot arm  130 , a distance D 2  between the article A and the second linear unit  132  of the robot arm  130 , etc. According to this method, the frequency of determining that interference will occur is less than that of the method shown in  FIG.  8 A . As a result, the frequency that the first operation is performed in parallel with the second operation can be increased, and the efficiency of the cargo handling task can be further improved. 
     First Modification 
     In the example shown in  FIGS.  6 A to  7 B , the existence or absence of interference of the robot arm  130  with the transfer device  160  and the article on the transfer device  160  is determined by using only the positional relationship in the Z-direction. The existence or absence of interference also may be determined using the positional relationship in the Y-direction. 
       FIG.  9    is a schematic view showing a function of a control device of a cargo handling apparatus according to a first modification of the embodiment. 
     According to the first modification shown in  FIG.  9   , in step S 2   a  after step S 1 , the planning part  192  generates plans for the articles that can be held. The planning part  192  calculates the priorities of the plans (step S 5   a ). Then, in step S 3   a,  the planning part  192  determines the interference of the robot arm  130  for the plans generated. Continuing in step S 4   a,  the planning part  192  stores the plans, the priorities, and the interference determination results for the articles that can be held. For example, the priority for the plan is calculated to be higher for articles having upper surfaces at higher positions. 
     The operation controller  193  confirms the plans, the priorities, and the interference determination results in step S 11 . The operation controller  193  selects the plan among the multiple plans that has the highest priority (step S 17   a ). The operation controller  193  determines whether or not the interference determination result related to the plan selected in step S 12  determines that interference will occur. When interference will not occur, the selected plan is performed in step S 14 . 
     When interference will occur, the operation controller  193  determines whether or not there is another plan that has not yet been selected in step S 17   a  (step S 17   b ). When there is another plan, the operation controller  193  selects the plan having the next highest priority in step S 17   a.  When there is no other plan, the operation controller  193  causes the robot arm  130  to standby until the previous article is transferred from the transfer device  160 . Subsequently, the plan that has the highest priority is performed in step S 14 . 
       FIG.  10 A ,  FIG.  10 B ,  FIG.  11 A , and  FIG.  11 B  are schematic views showing an operation of the cargo handling apparatus according to the first modification of the embodiment. 
     In the state shown in  FIG.  10 A , multiple articles that include an article A 11  and an article A 12  are placed on the pallet P. Articles A 13  and A 14  are placed on the transfer device  160 . The articles A 11  to A 14  are at the same level. For example, the article A 11  is determined to be the holding object with the highest priority. The article A 12  is determined to be the holding object with the highest priority after the article A 11 . The article A 11  is an example of the first article. The article A 12  is an example of the third article. The articles A 13  and A 14  are examples of the second article. 
     The Y-direction position of the article A 11  is the same as the Y-direction positions of the articles A 13  and A 14 . In other words, the article A 11  overlaps the articles A 13  and A 14  when viewed along the X-direction. Therefore, the robot arm  130  interferes with the articles A 13  and A 14  when the hand  120  holds the article A 11 . The operation controller  193  determines whether or not the article A 12  with the next highest priority can be held. The Y-direction position of the article A 12  is different from the Y-direction positions of the articles A 13  and A 14 . The article A 11  does not overlap the article A 13  or A 14  when viewed along the X-direction. Therefore, the robot arm  130  will not interfere with the article A 13  or A 14  when the hand  120  holds the article A 12 . The operation controller  193  determines that the article A 12  can be held without interference. According to the determination result, the operation controller  193  moves the hand  120  toward the article A 12  as shown in  FIG.  10 B . 
     On the other hand, in the state shown in  FIG.  11 A , the Y-direction position of the article A 11  is the same as the Y-direction position of the article A 13 . Also, the Y-direction position of the article A 12  is the same as the Y-direction position of the article A 14 . When there are no candidates for the holding object other than the articles A 11  and A 12 , the operation controller  193  determines that no article can be held without interference. As shown in  FIG.  11 B , the operation controller  193  moves the hand  120  toward the article A 11  with the highest priority after the articles A 13  and A 14  are transferred by the transfer device  160 . 
     The determination method of the interference based on the positional relationship in the Z-direction shown in  FIG.  8 A  or  FIG.  8 B  is applicable to determining the interference based on the positional relationship in the Y-direction. For example, the planning part  192  sets a virtual minimum rectangle surrounding the robot arm  130  in the X-Y plane. The planning part  192  determines whether or not the rectangle R interferes with the article on the transfer device  160 . Or, the planning part  192  may determine whether or not the components of the robot arm  130  interfere with the article on the transfer device  160  in the X-Y plane. 
     Advantages of the first modification will now be described. 
     Even when the heights of the article that is held and the article on the transfer device  160  are the same, there are cases where the Y-direction positions of such articles are shifted as shown in  FIG.  10 A . By using the positional relationship in the Y-direction to determine the interference, the frequency that the first operation is performed in parallel with the second operation can be increased, and the efficiency of the cargo handling task can be further improved. 
     In the example shown in  FIGS.  2 A to  4 B  and  FIGS.  6 A to  7 B , the hand  120  holds the article by using only the upper surface suction-gripping unit  121 . The hand  120  may be able to switch between methods of holding the article. For example, the cargo handling apparatus  100  can switch between a first holding method and a second holding method. In the first holding method, the cargo handling apparatus  100  holds the article by using only the upper surface suction-gripping unit  121 . In the second holding method, the cargo handling apparatus  100  holds the article by using both the upper surface and side surface suction-gripping units  121  and  122 . In the example shown in  FIGS.  2 A to  4 B  and  FIGS.  6 A to  7 B , the first operation is performed using the first holding method. 
       FIGS.  12 A to  12 C  and  FIGS.  13 A to  13 C  are schematic views showing another operation of the cargo handling apparatus according to the embodiment. 
     As shown in  FIG.  12 A , the robot arm  130  moves the hand  120  above the article A determined to be the holding object. Also, the Z-direction position of the transfer device  160  is set to the same position as the bottom surface of the article A to be held. The moving device  170  lowers the hand  120  toward the article A. As shown in  FIG.  12 B , the upper surface suction-gripping unit  121  and the side surface suction-gripping unit  122  respectively suction-grip the upper surface and side surface of the article A. As shown in  FIG.  12 C , the robot arm  130  transfers the article A that is held onto the transfer device  160 . For example, the robot arm  130  transfers the article A onto the transfer device  160  by sliding. At this time, the hand  120  may be oblique to the X-Y plane as illustrated. The contact area between the bottom surface of the article A and another article (or the pallet P) can be reduced thereby, and the friction can be reduced. 
     As shown in  FIG.  13 A , the hand  120  releases the holding by the upper surface suction-gripping unit  121  and the side surface suction-gripping unit  122 . As shown in  FIG.  13 B , the moving device  180  sets the Z-direction position of the transfer device  160  to the same position as the transfer device C. Also, the moving device  170  raises the hand  120  and the robot arm  130 . As shown in  FIG.  13 C , the transfer device  160  transfers the transferred article A to the transfer device C. The operation shown in  FIGS.  12 A to  13 A  corresponds to the first operation. The operation shown in  FIGS.  13 B and  13 C  corresponds to the second operation. 
     According to the second holding method, the stability of the holding is better than that of the first holding method because the upper surface and side surface of the article are held. Also, compared to when the article is raised, the time of the first operation can be reduced by sliding the article. Therefore, the efficiency of the cargo handling task can be further increased. According to the first holding method, the article A can be transferred regardless of the state between the transfer device  160  and the article A that is held because the article A is raised. 
     An instruction that indicates the use of one of the first holding method or the second holding method may be input to the cargo handling apparatus  100 . The cargo handling apparatus  100  switches the first holding method and the second holding method according to the received instruction. The instruction may be input by a user or may be transmitted by a higher-level host computer, etc. Whether to use the first holding method or the second holding method may be determined based on the measurement results of the first and second measuring instruments  141  and  142 . For example, the second holding method is used when the path between the transfer device  160  and the article determined to be the holding object is flat and the article is slidable. The first holding method is used when the path is not flat. The path is the upper surface of the other article or the upper surface of the pallet P. 
     Second Modification 
     According to the first modification, when interference of the robot arm  130  will occur when holding one article, it is determined whether or not another article can be held without interference. In contrast, in a second modification, the previous article is placed on the transfer device  160  so that interference will not occur when the next article is held. 
       FIG.  14    is a schematic view showing a function of a control device of a cargo handling apparatus according to the second modification of the embodiment. 
     According to the second modification shown in  FIG.  14   , in step S 2   b  after step S 1 , the planning part  192  generates plans for the article to be transferred directly thereafter (first) and the article to be transferred next (second). The planning part  192  generates operation paths related to placement positions for the first article while changing the placement position of the article on the transfer device  160 . Thereby, multiple plans are generated for the first article. For example, a plan is generated for the second article to minimize the operation path. 
     In step S 3   b,  the planning part  192  determines whether or not the robot arm  130  will interfere with the transfer device  160  or the article on the transfer device  160  when performing the first operation for the first article for each plan related to the first article. Furthermore, the planning part  192  determines whether or not the robot arm  130  will interfere with the first article on the transfer device  160  when performing the first operation for the second article for each plan related to the first article. The planning part  192  calculates the priorities for the plans related to the first article (step S 5   b ). The priority is calculated based on the operation distance and the interference determination result. Specifically, the priority that is set is increased as the operation path decreases. The priority is greatly reduced for plans in which interference will occur. The planning part  192  stores the multiple plans related to the first article and the priorities and interference determination results for the plans. 
     The operation controller  193  confirms the plan with the highest priority and the interference determination result of the plan in step S 11 . As described above, the priority is greatly reduced for the plans in which interference will occur. Therefore, as a result, a plan among the multiple plans related to the first article in which interference by the robot arm  130  will not occur is selected. Thereafter, similarly to the cargo handling method shown in  FIG.  5   , steps S 12  to S 16  are performed. 
       FIG.  15 A ,  FIG.  15 B ,  FIG.  16 A , and  FIG.  16 B  are schematic views showing an operation of the cargo handling apparatus according to the second modification of the embodiment. 
     In the state shown in  FIG.  15 A , multiple articles that include articles A 21  and A 22  are placed on the pallet P. For example, the upper surface of the article A 21  is positioned higher than the upper surface of the article A 22 . The article A 21  is determined to be transferred first, and the article A 22  is determined to be transferred second. 
     The planning part  192  generates plans for the article A 22 . For example, as shown in  FIG.  15 B , a plan P 2  that has the shortest operation path to the transfer device  160  is generated. The planning part  192  also generates multiple plans for the article A 21 . For example, as shown in  FIG.  16 A , multiple plans P 1   a  to P 1   n  are generated while changing the placement position on the transfer device  160 . The planning part  192  determines whether or not the robot arm  130  will interfere with the article A 21  on the transfer device  160  when performing the first operation for the article A 22  for each of the multiple plans P 1   a  to P 1   n.  Based on the distance of the operation path and the determination result of the interference, the planning part  192  sets the priorities of the multiple plans P 1   a  to P 1   n.  As a result, for example, the priority of a plan P 1   z  shown in  FIG.  16 B  is set to be the highest. According to the plan P 1   z,  the robot arm  130  does not interfere with the article A 21  when performing the first operation for the article A 22 . 
     According to the second modification, the first operation for the article A 21  is performed so that interference of the robot arm  130  does not occur in the first operation for the article A 22 . Therefore, the first operation for the article A 22  can be performed in parallel with the second operation for the article A 21 . The frequency that the first operation is performed in parallel with the second operation can be increased, and the efficiency of the cargo handling task can be further improved. 
       FIG.  17    is a schematic view showing a hardware configuration. 
     The control device  190  includes, for example, the hardware configuration shown in  FIG.  17   . A processing device  90  shown in  FIG.  17    includes a CPU  91 , ROM  92 , RAM  93 , a memory device  94 , an input interface  95 , an output interface  96 , and a communication interface  97 . 
     The ROM  92  stores programs that control the operations of the computer. Programs that are necessary for causing the computer to realize the processing described above are stored in the ROM  92 . The RAM  93  functions as a memory region into which the programs stored in the ROM  92  are loaded. 
     The CPU  91  includes a processing circuit. The CPU  91  uses the RAM  93  as work memory to execute the programs stored in at least one of the ROM  92  or the memory device  94 . When executing the programs, the CPU  91  executes various processing by controlling configurations via a system bus  98 . 
     The memory device  94  stores data necessary for executing the programs and/or data obtained by executing the programs. 
     The input interface (I/F)  95  connects the processing device  90  and an input device  95   a.  The input I/F  95  is, for example, a serial bus interface such as USB, etc. The CPU  91  can read various data from the input device  95   a  via the input I/F  95 . 
     The output interface (I/F)  96  connects the processing device  90  and an output device  96   a.  The output I/F  96  is, for example, an image output interface such as Digital Visual Interface (DVI), High-Definition Multimedia Interface (HDMI (registered trademark)), etc. The CPU  91  can transmit data to the output device  96   a  via the output I/F  96  and cause the output device  96   a  to display an image. 
     The communication interface (I/F)  97  connects the processing device  90  and a server  97   a  outside the processing device  90 . The communication I/F  97  is, for example, a network card such as a LAN card, etc. The CPU  91  can read various data from the server  97   a  via the communication I/F  97 . A camera  99   a  images articles and stores the images in the server  97   a.  The camera  99   a  functions as the imaging part  141   a.  LRFs  99   b  and  99   c  function as the distance sensors  142   a  and  143   a.    
     The memory device  94  includes at least one selected from a hard disk drive (HDD) and a solid state drive (SSD). The input device  95   a  includes at least one selected from a mouse, a keyboard, a microphone (audio input), and a touchpad. The output device  96   a  includes at least one selected from a monitor, a projector, a speaker, and a printer. A device such as a touch panel that functions as both the input device  95   a  and the output device  96   a  may be used. 
     The processing of the various data described above may be recorded, as a program that can be executed by a computer, in a magnetic disk (a flexible disk, a hard disk, etc.), an optical disk (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD±R, DVD±RW, etc.), semiconductor memory, or another non-transitory computer-readable storage medium. 
     For example, the information that is recorded in the recording medium can be read by the computer (or an embedded system). The recording format (the storage format) of the recording medium is arbitrary. For example, the computer reads the program from the recording medium and causes a CPU to execute the instructions recited in the program based on the program. In the computer, the acquisition (or the reading) of the program may be performed via a network. 
     According to the embodiments described above, a cargo handling apparatus, a control device, a cargo handling method, a program, and a storage medium are provided in which the efficiency of the cargo handling task can be increased. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention. The above embodiments can be practiced in combination with each other.