Abstract:
A transport system for piece goods includes a conveyor for moving the piece goods along a conveying path, an unloading device including a multi-axis manipulator for unloading piece goods from the conveyor, and a clearing tool. The clearing tool is moved relative to the conveyor by the multi-axis manipulator to discharge a piece good from the conveyor, and the movement of the clearing tool includes a directional component transverse to the direction of movement of the conveying path and a directional component in the direction of movement of the conveying path.

Description:
TECHNICAL FIELD 
     The invention relates to a transport system for piece goods, having a conveyor system with at least one piece goods carrier moved by the conveyor system and an unloading device for removing the piece goods from the at least one piece goods carrier at an unloading point. The invention also relates to an associated method for unloading piece goods from a piece goods carrier of a conveyor system at an unloading point, and to a utilization for that purpose in luggage conveyor systems. 
     BACKGROUND 
     EP 1 388 510 A1 describes a transport system for piece goods containers, in particular for luggage containers on an essentially horizontal conveyorway having at least two conveyors spaced apart, of which at least one conveyor is driven, as well as having at least one device for unloading the piece goods, using gravity by tilting the piece goods container into an unloading position transverse to its transport direction. A running rail loop runs in space so that the piece goods container while being transported is lifted on one side from the adjacent conveyor by the device by means of the positively guided coupling element and is rotated into its tilted position. 
     DE 20 2008 009 280 U1 describes a conveyor device having a number of transport units that are movable along a guiding apparatus. The conveyor device described there, having a number of transport units movable along a guiding apparatus, has on its top side a push-off device that is drivable contrary to a travel direction of the transport units, for gentle loading and/or discharging of pieces of cargo. 
     SUMMARY 
     The object of the invention is to provide a transport system for piece goods, wherein the piece goods are removed from the piece goods carrier at their unloading point in an improved manner. 
     The problem of the invention is solved by a transport system for piece goods, having a conveyor system with at least one piece goods carrier moved by the conveyor system and an unloading device for removing the piece goods from the at least one piece goods carrier at an unloading point, wherein the unloading device is constituted by a freely programmable manipulator positioned at the unloading point. 
     The freely programmable manipulator is set up in this case to remove each piece of cargo arriving at the unloading point from the piece goods carrier by moving the manipulator. The use of a freely programmable manipulator results on the one hand in there being no need to have unloading devices on the piece goods carriers or conveyed along with them, and on the other hand in the ability to operate on the piece goods with differing motion sequences of the manipulator as needed, depending on the piece goods delivered by the particular piece goods carrier, in order to remove them from the piece goods carrier. Because the plurality of piece goods carrier-based unloading devices known from the existing art are replaced according to the invention by a single manipulator at the unloading point, it is possible to save as many unloading devices as there are piece goods carriers circulating in the transport system—except for one. 
     For example, at airports, transport containers are employed in luggage conveyor systems in order to transport the cargo, for example air travel luggage, gently and rapidly, so that luggage traveling with the passengers can be transloaded quickly at connection airports, and the passengers can take advantage of their connecting flights faster. Uniform conveyor performance and a high degree of system availability are also required. The transport containers are loaded either from above or from the side. Loading from above has the disadvantage that the cargo, i.e., the luggage, falls into the transport container from above, causing very severe wear on the transport containers over time. Loading from the side requires active conveyor devices, which had to be provided heretofore on each individual transport container. These are for example tilting devices or lateral conveyor belts. The transport containers become complex and expensive, due to the high cost of conveyor devices for each transport container. The transport containers are unloaded in this case using these active conveyor devices, or else the entire container must be tilted. It is often necessary to this end to implement complicated gripping mechanisms, such as clamps or permanent magnets. Besides these gripping mechanisms and the transport containers, often substantial portions of the conveyor system components are also tilted. This has the disadvantage that heavy structural elements must be moved, or that energy and/or data must be transferred to moving parts. This also results in significant wear. With many systems of this sort the conveyer system must be stopped during the tilting, which limits the throughput of the conveyor lines. With problematic cargo, such as wet leather suitcases, it is sometimes not possible to overcome the cohesive friction despite tilting the transport container, so that the cargo, i.e., the suitcase, remains in the transport container and thus causes a disruption. 
     The invention provides a robot-based solution. 
     Instead of expensive emptying mechanisms, a robot, whose sequence of movements can be synchronized with the movement of the container, clears off the loaded piece goods carrier, for example a tray, in particular for suitcases. The robot can carry as a tool a simply designed sliding device. The sliding device can be designed as a push broom. The horizontal sliding direction can be perpendicular to the motion of the container, from the perspective of the moving container. The shape and size of the sliding device can be adapted to the shape of the container, which makes it possible to ensure that even small pieces of cargo are unloaded reliably. 
     The transport system according to the invention can offer advantages through the fact that the transport system can be supplied inexpensively, can easily be retrofitted, or can be adapted in a simple manner to changed conditions for transported and/or conveyed goods. At the same time, discharge is possible at many or various locations of the conveyor system, on both the left and right sides. It is possible to achieve an increase in throughput with the transport system according to the invention, since it may not be necessary to stop the piece goods carriers. Increased throughput means greater line capacity and therefore less space needed for the total system. The unloading can be done with greater reliability. The clearing speed and acceleration can be set individually. For example, the transport system can be adapted to the properties of the goods being transported, such as weight, size, sensitivity or the current transport speed. In addition, the chute width can be reduced because of the greater precision of the freely programmable manipulator, so that less space is needed for the transport system. The transported goods are handled more gently due to the discharge using a freely programmable manipulator. Additionally, robot-based loading is also possible. Analogously to the unloading of the containers, loading by the freely programmable manipulator is also possible. The clearing tool can be adapted mechanically for that purpose. 
     A clearing tool for removing the piece goods from their piece goods carriers, in particular for discharging them onto a removal device at the unloading point, can be combined with the freely programmable manipulator. The clearing tool can be adapted to the size, shape and contour of the piece goods carriers. So with a piece goods carrier that is at least approximately flat and for example rectangular, the clearing tool can be constituted of a flat slide, which extends across the width of the piece goods carrier and is oriented essentially perpendicular to the floor of the piece goods carrier. If the piece goods carrier is shaped differently, the clearing tool can have a correspondingly adapted shape. In particular, the clearing tool can be adapted to the piece goods carrier in such a way that even very small piece goods are also unloaded reliably. 
     The clearing tool can be actuated by the freely programmable manipulator to push off, in particular in a direction transverse to the transport direction of the conveyor system. In principle, the clearing tool can clear the piece goods from the piece goods carrier using any sequence of motions. In a specific embodiment, the clearing tool can be set up to push the piece goods off. Pushing off can be accomplished for example by the clearing tool having a slide which strokes above or along the surface of the piece goods carrier from one side of the piece goods carrier to the other side, and in so doing carries the piece goods with it, i.e., pushes them ahead of it, and forces them off the piece goods carrier. 
     In all designs it is possible to combine a clearing tool with the freely programmable manipulator, whose motion is synchronized with the piece goods carrier to be cleared, which is being moved by the conveyor system. That enables the piece goods to be unloaded even when the particular piece goods carrier that is passing the unloading point is in motion. As a result, stopping and restarting the piece goods carrier can be eliminated, so that the transport system is in motion without interruption and is constantly available. 
     In one design, the clearing tool can be synchronized with the piece goods carrier by a motion of the axes of the freely programmable manipulator. In the case of a stationary manipulator, i.e., one that is positioned immovably at the unloading point, the clearing tool alone can be synchronized to the motion of the piece goods carrier by moving the axes of the freely programmable manipulator. With synchronization of this sort the clearing tool executes a motion not only with a directional component transverse to the direction of motion of the piece goods carrier, but also with a directional component in the direction of motion of the piece goods carrier, and in particular at the same velocity as the piece goods carrier. 
     In one design, additionally or alternatively the transport system can include a linear axis, and the clearing tool can be synchronized with the piece goods carrier by a motion of the linear axis on which the freely programmable manipulator is movably supported. In that way the clearing tool can be synchronized with the piece goods carrier by superimposing motions of the axes of the freely programmable manipulator and the motion of the linear axis. In a specific design, the directional component transverse to the direction of motion of the piece goods carrier can be generated solely by the motions of the axes of the freely programmable manipulator, and the directional component in the direction of motion of the piece goods carrier solely by the motion of the linear axis. Alternatively, a mixed motion from the axes of the freely programmable manipulator and the linear axis can also be produced. 
     A method according to the invention for unloading piece goods from a piece goods carrier of a conveyor system at an unloading point, in particular using one of the described transport systems, provides the following steps: 
     Transporting the piece goods located on at least one piece goods carrier of the conveyor system to the unloading point, and clearing the piece goods from the piece goods carrier using a clearing tool that is guided by the freely programmable manipulator positioned at the unloading point. 
     In a refinement of the method, clearing of the piece goods from a piece goods carrier that is in motion can be accomplished by a clearing tool that is guided by a freely programmable manipulator positioned at the unloading point, by a motion of the manipulator that is synchronized with the motion of the piece goods carrier. 
     The motion of the clearing tool that is synchronized with the motion of the piece goods carrier can be executed by actuating the axes of the manipulator. 
     Alternatively or in addition, the motion of the clearing tool that is synchronized with the motion of the piece goods carrier can be executed by actuating the motion of a linear axis on which the manipulator is movably supported. 
     The motion of the clearing tool that is synchronized with the motion of the piece goods carrier can be executed by superimposed actuation of the axes of the manipulator and actuation of the motion of the linear axis. 
     In all variants of the method according to the invention, the motion of the manipulator can be executed with different travel conditions for the motion of the clearing tool depending on a feature of the piece goods to be cleared, in particular on the basis of data of the piece goods that are registered by a measuring and/or identification system. For example, a detecting device can be provided in the transport system which registers data of the piece goods and possibly passes said data on, so that the motion of the manipulator can be adapted on the basis of the data. The detecting device, or the measuring and identification system, can be provided on the manipulator or can be attached to it. For example, the piece goods can be provided with transponders or RFID tags for that purpose. 
     Thus for example at least one travel condition from the group of travel path, velocity and acceleration can be changed or adapted to the adapted movement of the clearing tool depending on a feature of the piece goods to be cleared. Depending on whether the item is for example a very strong hard-shell suitcase or a soft fabric bag, in the exemplary case of the hard-shell suitcase the clearing tool can be guided more rapidly and the hard-shell suitcase removed from the piece goods carrier with greater force, or in the exemplary case of the fabric bag the clearing tool can be guided more slowly and the fabric bag removed from the piece goods carrier with less force. At the same time, there can also be provision for reducing the velocity of the piece goods carrier according to the feature of the piece goods to be cleared. 
     In all variants of the method according to the invention, the motion of the manipulator can be executed with different travel conditions for the motion of the clearing tool depending on a feature of the piece goods carrier to be cleared, in particular depending on the shape of the piece goods carrier. For example, the shape of the piece goods carrier can be taken into account in the unloading motion, in order to unload the piece goods gently. For example, the robot or manipulator can make allowance for a convex bowl shape of the piece goods carrier, whereby the reliability of unloading is increased. 
     The motion of the manipulator with different travel conditions for the motion of the clearing tool can be executed depending on at least one feature of the piece goods to be cleared, from the group of shape, dimensions, mass and sensitivity to impact of the piece goods. 
     The methods according to the invention can be employed in luggage conveyor systems, in particular at airports. The transport systems according to the invention can be used in luggage conveyor systems, in particular at airports. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention will be described on the basis of  FIGS. 1 through 3 . The detailed descriptions of these concrete exemplary embodiments also produce additional general features and advantages of the present invention. 
       The figures show the following: 
         FIG. 1  a perspective view of a transport system for piece goods, having a conveyor system and a piece goods carrier, as well as a stationary manipulator as an unloading device; 
         FIG. 2  a perspective view of a transport system for piece goods, having a conveyor system and a piece goods carrier, as well as a manipulator movable on a linear axis as an unloading device; 
         FIG. 3  a schematic depiction of the method according to the invention for unloading piece goods, with various designs for the motion of the manipulator. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts one embodiment of a transport system  1  based on a short segment of a conveyor system  2 . Conveyor system  2  has a conveying path  3 , along which as an example a single one of a plurality of piece goods carriers  4  is movably supported. Piece goods carrier  4  is shown schematically with a rectangular support floor  5 . Piece goods carrier  4  can be designed differently, however, depending on the piece goods  6  to be transported. For example, piece goods carrier  4  can also have in particular a round or circular contour and/or a dish-shaped floor  5  instead of a flat support floor, or may also be shaped for example as a tub, luggage tray or container. Preferably, piece goods carrier  4  is movable along conveying path  3 , but otherwise is rigidly mounted, i.e., is of non-pivotable, non-tiltable design.  FIG. 1  shows the section of conveying path  3  in the area of an unloading point  7 . In the area of unloading point  7 , a removal device  8  in the exemplary version of an unloading slide  8   a  is shown. A freely programmable manipulator  9   a  as an unloading device  9  in the form of an industrial robot  9   b  is placed at unloading point  7 . 
     In the embodiment shown in  FIG. 1 , by way of example industrial robot  9   b  is positioned in a fixed location on a base  10  as stationary manipulator  9   a . However, manipulator  9   a  or industrial robot  9   b  can also be attached directly to the floor. The depicted industrial robot  9   b  is designed as an articulated-arm robot having six axes, so that a flange  11  of industrial robot  9   b  is movable in a straight line in all three spatial directions and rotationally in all three spatial directions. A clearing tool  12  is attached to flange  11 . In the depicted exemplary embodiment, clearing tool  12  is designed to clear or push off piece goods  6  in a direction R transverse to the transport direction F of conveying path  3  of conveyor system  2 . Instead of a gripper with form-fitted operation, clearing tool  12  clears piece goods  6  off of piece goods carrier  4  by a sliding motion. Clearing tool  12  can have a slide  13  for that purpose, as shown. Slide  13  can extend over the entire width of piece goods carrier  4 . Slide  13  can have a height that is adapted to the height of the piece goods  6  being transported, or in particular may have the same height as the latter. Slide  13  can be designed rigidly, or flexibly, as indicated in  FIG. 1 . A flexible design of slide  13  enables slide  13  to adapt elastically or fit snugly to the floor of piece goods carrier  4 , and possibly to the shape of piece goods  6 . The motion of the manipulator can also be adapted to the shape of the piece goods carrier. Thus for example, with a dish-shaped piece goods carrier the manipulator can execute an arc-shaped or curving motion, which is oriented to the shape of the piece goods carrier. Flexibility of slide  13  can be achieved for example by pre-stressed, rotatable supporting of a rigid plate on a holder  14 , or by firmly clamping an elastic lip  15  to holder  14 , as indicated in  FIG. 1 . Holder  14  can be connected to flange  11  of manipulator  9   a  or industrial robot  9   b  directly, or through a connecting element, as shown. 
     In the embodiment according to  FIG. 2 , manipulator  9   a  or industrial robot  9   b  is not attached immovably, but rather is movably supported on a linear axis  17 . Linear axis  17  provides an additional degree of freedom, in order to be able to move or position the flange with clearing tool  12  attached thereto. In a special embodiment, a carriage  18  of linear axis  17  is movable along a straight path. The path can run in particular parallel to the transport direction F of conveying path  3  of conveyor system  2  in a section in the area of unloading point  7 . By means of linear axis  17 , the manipulator  9   a  or industrial robot  9   b  attached to carriage  18  can be moved in particular synchronously with the motion of piece goods carrier  4 . 
     In the embodiment according to  FIG. 2 , a clearing tool  12  according to the design as shown in  FIG. 1  and described in the associated description can be used. Alternatively, an alternative clearing tool  12  can be used, for example as depicted in  FIG. 2 . The clearing tool  12  shown in  FIG. 2  has a plurality of tines  19   a  or bristles  19   b  spaced at a distance from each other, instead of a continuous elastic lip  15 . The tines  19   a  can be rigidly attached, or pre-tensioned and spring-mounted on holder  14 . The bristles  19   b  can have elastic characteristics, and in particular can be made of inherently elastic material. In this case the bristles  19   b  can be rigidly attached to holder  14 , or can be movably mounted on holder  14 , in particular pre-tensioned and elastically. The tines  19   a  and/or bristles  19   b  can be of equal or differing lengths, and in particular their lengths can be matched to the shape of support floor  5  of piece goods carrier  4 . The elastic hardness of the tines  19   a  and/or bristles  19   b  can also be adapted to the piece goods  6 . 
       FIG. 3  shows a schematic depiction of the method according to the invention for unloading piece goods, with various designs for the motion of the manipulator. 
     One method according to the invention for unloading piece goods  6  from a piece goods carrier  4  of a conveyor system  2  begins with a step A, in which piece goods  6  located on at least one piece goods carrier  4  of conveyor system  2  are transported to unloading point  7 . 
     In the first alternative ALT1, in the event that piece goods carrier  4  comes to a stop (ALT1, NEIN) in the area of unloading point  7 , according to step B piece goods  6  are cleared from stationary piece goods carrier  4  by means of a clearing tool  12 , which is guided by the freely programmable manipulator  9   a  positioned at unloading point  7 . 
     In the first alternative ALT1, in the event that piece goods carrier  4  is in motion (ALT1, JA) in the area of unloading point  7 , in step C piece goods  6  are cleared off by clearing tool  12  by means of a motion of manipulator  9   a  that is synchronized with the motion of piece goods carrier  4 , either in the case of alternative ALT2A according to step D by actuating the axes of manipulator  9   a , or in the case of alternative ALT2B according to step E by actuating the motion of a linear axis  17  on which manipulator  9   a  is movably supported. 
     Clearing of piece goods  6  by clearing tool  12  by means of a motion of manipulator  9   a  that is synchronized with the motion of piece goods carrier  4  in step C can also be accomplished by a superimposed motion of actuating the axes of manipulator  9   a  according to step D with actuating the motion of a linear axis  17  on which manipulator  9   a  is movably supported, according to step E.