Abstract:
An end effector for a robot having an array of suction cups includes an air control valve connected to each suction cup. Each valve can be individually operated so that specific zones of suction cups may be activated while others are dormant. The dormant suction cups are closed to the sub-atmospheric pressure, so that leakage of air through unused suction cups is avoided, while only the suction cups of the selected zone perform the picking of the work products. This allows the end effector to provide accurate and constant sub-atmospheric pressure to the work products during the picking process.

Description:
TECHNICAL FIELD 
     The present disclosure concerns packaging equipment and, more particularly, concerns a robotic packaging apparatus that includes an end effector for collecting work products of different shapes and sizes in different patterns for delivery to a receptacle, such as to a shipping container. 
     BACKGROUND OF THE DISCLOSURE 
     In robotic packaging operations, a producer might desire to ship work products in shipping containers of a standard shape and size. The shape and size of the individual work products might be different from one job to the next. In order to ship in standard size containers it may be required to retrieve and collect the products of one size and shape on the end effector of the robot in a different pattern than for other products. 
     For example, in the bakery industry a producer typically will produce several sizes of loaves of bread from time to time and has one basket size in which he/she ships the products. The different products may fit best in the basket when configured in different arrangements or pack patterns than other sized products. The pack patterns are dependent of the product sizes. A robot may be used to pick the products up with multiple picks of the end effector at various positions to form the desired pattern of the products on the end effector, and the robot then places the products into the basket all at once in the desired pattern. 
     Usually a single vacuum source with high flow and low vacuum level for the pick-up force is desirable and most commonly used. Multiple suction cups typically are used as the vacuum retrievers to provide the seal between the vacuum source and the objects being picked. When multiple picks are required for one delivery of the products to the basket, the vacuum must be applied to certain suction cups on the end effector to enable picking or holding of the product in that pick zone while other zones of the suction surface must not allow vacuum flow because those zones of the end effector are not yet covered by work products. To accomplish this, the vacuum source may be split in several tubes and then the tubes are valved open or closed to allow vacuum to flow to different sectioned-off portions of the suction surface of the end effector. 
     The system described above is not ideal when several different zones are required to conduct the picking functions and/or the zones must change in shape for picking different products. If there are too many pick zones of vacuum retrievers then the vacuum lines become small and restrict the vacuum flow. 
     A common solution was to provide multiple end effectors that have 2 to 6 pick zones in the suction surface strategically placed for the specific pattern or similar patterns that it is designed for. This is cost prohibitive as some producers have dozens of different shaped and sized products and would require dozens of different end effectors. 
     Similarly, another method of having a non-zoned end effector was to have the vacuum source connected with a large hose to a large plenum. The bottom of the plenum is then populated with multiple suction cups that allow high flow between the cup and the plenum. This may be a solution to some of the problems but is limited because it is not zoned and therefore cannot perform multiple picks. If multiple picks are attempted then the first pick often fails due to leakage from the other open cups. 
     Therefore, there exists a need for an improved universal end effector that can be programmed to open vacuum flow to only selected zones of suction cups as required to form desired patterns or zones of suction. The end effector would minimize vacuum loss through suction cups that are not sealed over a product. Preferably, the end effector would have high enough resolution of suction cups to be able to form substantially any pattern for any common sized product to be picked and placed by a robot. The end effector would allow a high volume of vacuum flow to each suction cup that is to engage the work product substantially without loss of sub-atmospheric pressure in the vacuum source through the other suction cups, and without complex and restrictive chambers and multiple hoses. 
     SUMMARY DESCRIPTION 
     Briefly described, one form of the present process concerns a method of selectively robotically collecting work products in a selected pattern from an accumulation of work products and placing the work products in a receptacle. The method includes orienting an end effector to engage some of the work products in the accumulation of work products with a plurality of vacuum retrievers in a first zone of the vacuum retrievers, applying a sub-atmospheric air pressure to the vacuum retrievers in the first zone of vacuum retrievers while avoiding drawing an air pressure in the remaining vacuum retrievers, and retrieving work products from the accumulation of work products with the vacuum retrievers in the first zone of the end effector. Then re-orienting the end effector with respect to the accumulation of work products and re-engaging the accumulation of work products with a second zone of the vacuum retrievers. Sub-atmospheric air pressure is applied to the vacuum retrievers in both the first and second zones of vacuum retrievers, and the work products are retrieved with the vacuum retrievers in the second zone of the end effector. These steps may be repeated for several picks until the desired pattern of work products are gathered on the end effector. Then the end effector places the work products in registration with a receptacle, and the sub-atmospheric air pressure to the work products is terminated to release the work products from the end effector. 
     In another embodiment, the apparatus may include a robot with an end effector for retrieving work products in a selected pattern from an accumulation of work products and for placing the retrieved work products in the selected pattern in a receptacle. The end effector may comprise a vacuum plenum housing, an array of vacuum retrievers such as suction cups suspended from the vacuum plenum housing for engaging the work products. Air control means are connected to each vacuum retriever for applying a sub-atmospheric air pressure of the vacuum plenum housing to each of the vacuum retrievers that are to retrieve work products while avoiding the application of sub-atmospheric air pressure of the vacuum plenum to the vacuum retrievers that are not to retrieve the work products. 
     Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1A  is an isometric view of a robot and its vacuum assisted programmable zoned end effector and the standard receptacle for receiving the work product. 
         FIG. 1B  is a diagram of a plan view of a desired configuration of the work product on the vacuum assisted zoned end effector as picked from an accumulation of the work products when to be delivered to a standard receptacle. 
         FIG. 1C  is a diagram of another example of a desired configuration of the work product on the vacuum assisted zone end effector. 
         FIG. 2A  is an isometric view of the robot and its end effector of  FIG. 1A , showing how some of the vacuum retrievers of the end effector have picked some of the work products. 
         FIG. 2B  is a diagram of the work products as picked by the end effector of  FIG. 2A . 
         FIGS. 3A-3D  are progressive illustrations of the vacuum face of the end effector, showing the pattern of the work products as they are progressively picked by the end effector. 
         FIG. 4A  is an end cross section of the end effector. 
         FIG. 4B  is a detailed illustration of the end effector of  FIG. 4A . 
         FIG. 5  is a block diagram of an example embodiment of a method of using the end effector of  FIG. 1  to achieve a desired configuration of work products. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several views,  FIG. 1A  illustrates a robot  10  of conventional articulating design, being pivotal about and upright axis, having a rocker arm  12  mounted on a rotary stanchion  14 , and control arm  16  that has the capacity to rotate in the distal end of the rocker arm  12 . The end effector  18  is mounted to the distal end of the control arm  16  and its movements are controlled by a program entered in the robot&#39;s computer system. The end effector can be rotated, raised, lowered and moved in lateral directions, as is common in the art and in accordance with its programmable control system. 
     As shown in  FIG. 1A , the end effector  18  has been placed in alignment with the receptacle  20  which is a packing container. The work products  22  have been released by the end effector  18  and have been deposited on the bottom wall of the receptacle  20 . In the embodiment illustrated, the receptacle is a box-shaped item but may be a basket, tray, pallet, or various other receptacles or surfaces. For purposes of illustration, without restriction, the invention is disclosed herein as being an apparatus and product for packing loaves of bread  22 , and the details of the invention are directed to that product. 
       FIG. 2A  shows the robot  10  from a different perspective, showing the end effector  18  in a position that reveals the suction surface  19  of the end effector. The suction surface  19  includes an array of vacuum retrievers, such as the corrugated or “bellowed” suction cups  24  that are to be applied to and that are to pick the loaves of bread or other work product. 
       FIGS. 1B and 1C  show sample arrangements of a layer of loaves of bread  22  when placed in a receptacle. A typical loaf of bread may be four inches wide and fourteen inches long, wrapped in a plastic film bag that has extra material gathered at one end to close about the end of the loaf. An example of the basket used by the producer to ship the loaves may have an inside dimension of twenty-two inches by twenty-eight inches. 
     The desired pattern for best fitting the most loaves of this size in this size basket is shown in  FIG. 1B  and is to have two loaves end-to-end on the twenty-eight inch dimension side of the basket. Next, another two loaves are placed end-to-end against the first two loaves. Finally seven loaves are turned perpendicular to the previous loaves so that their fourteen inch dimension fits the remaining fourteen inch available space in the basket. This allows eleven loaves per basket which is the most loaves possible for his size loaves in this size basket. If the loaves are of a different shape or size, or if the receptacle is of a different shape or size, the arrangement of the loaves is likely to change to better fit the dimensions of the receptacle. 
     The basket for the loaves in the arrangement of loaves of  FIG. 1C  may be of different dimensions or the loaves may be different in size from  FIG. 1B , so the best arrangement of loaves  22  may be different.  FIG. 1C  shows a packing arrangement for 10 loaves. 
     As shown in  FIG. 2A , an array of suction cups  24  on the suction surface  19  of the end effector is formed in a rectangle, with the suction cups arranged in columns and lines. As shown in  FIG. 2B , the suction cups are identified by columns and rows, with the columns identified as A-N and the rows identified as  1 - 11 . It will be noted that  FIG. 2B  shows that the first pick  29  is of two loaves of bread  22 A that occupy suction cups in columns A-G and rows  1 - 4 . 
     When loaves of bread have been bagged in a bagging machine, they are moved on a surface conveyor  26  with their long dimension leading. The loaves are conveyed to the end of the surface conveyor against a stop  28  and are gathered at the stop in a side-by-side accumulation. Once several products accumulate, the robot may begin its picking functions. 
     An example of the picking steps is shown in  FIGS. 3A-3D . In this example, the programmable end effector  18  moves from its rest position in  FIG. 3A  over to the accumulation of loaves  22  on the surface conveyor  26  as shown as shown by arrow a and rotates as shown by arrow b and moves down onto the two end loaves  22 A at the stop  28  of the surface conveyor  26  and first picks loaves  22 A at one corner of its suction surface  19 . Suction is applied to suction cups the zone identified as  1 A to  1 G,  2 A to  2 G,  3 A to  3 G, and  4 A to  4 G. The end effector then holds the two loaves on its suction surface  19 . When the first loaves  22 A have been lifted away from the accumulation of loaves on the conveyor, the conveyor advances the accumulation of loaves to the conveyor stop  28 . The robot then moves the end effector over as shown by arrow c and picks two more loaves  22 B in alignment with the first two loaves  22 A by again coming down over and retrieving the loaves. Suction is applied to suction cups in the zone identified as  1 H to  1 N,  2 H to  2 N,  3 H to  3 N, and  4 H to  4 N. 
     The end effector then holds all four loaves on its suction surface  19  and the surface conveyor again advances its accumulation of loaves to the end stop  28 . The robot then rotates the end effector 90 degrees as shown by arrow d and moves the end effector over as shown by arrow e to place the empty portion of the suction surface over the loaves on the surface conveyor. The empty portion of the suction surface  19  then picks seven loaves  22 C in side-by-side arrangement. Suction is applied to suction cups in the pick zone identified as columns  5 - 11  and columns A-N. All of the loaves are held on the suction surface of the end effector, and the robot moves the end effector into registration with the basket and releases the loaves into the basket. 
     As shown in  FIGS. 4A and 4B , the end effector  18  includes a vacuum plenum housing  30 , with the housing including a top wall  32 , a bottom wall  34 , and four perimeter walls, such as perimeter walls  35  and  36 . The walls of the housing  30  define a vacuum plenum  38  and an air outlet opening  40  on the top wall  32  is connected to the inlet of a compressor  41  that draws air from the plenum. The suction cups  24  are suspended from the bottom wall  34  of the vacuum plenum housing  30  for picking work products  22 . 
     The bottom wall  34  of the plenum housing defines an array of air passages  42  over its length and width for the passage of air from below the bottom wall upwardly into the plenum chamber  38 . Each suction cup  24  is mounted to the bottom wall  34  of the plenum chamber by conventional means, such as by the insertion of a washer in the upper corrugation of the suction cup, above the bottom wall  34  of the vacuum plenum housing  30 , so that the upper ends of the suction cups are firmly and permanently held in place, with the middle and lower portions of the suction cups suspended downwardly from the bottom wall  34 . With this arrangement, the air passage  42  extends from the internal area of the suction cup upwardly through the washer  44 , into the vacuum plenum housing  30 . 
     A plug  46  and a plug actuator  48  connected together by rod  47  are suspended from the top wall  32  over each air passage  42 . Each plug  46  independently reciprocates between a lower position in which it engages and blocks the upper portions of its suction cup. This blocks the air passage  42 , and prohibits the movement of air up through the hollow suction cup, through the air passage, and into the vacuum plenum  38 . When air is allowed to be drawn from a suction cup up into the vacuum plenum housing  30 , the plug actuator  48  retracts its plug  46  away from the washer  44 , thereby opening the large and minimally restrictive passage  42 . This supplies the sub-atmospheric pressure of the vacuum plenum  38  to the interior of the suction cup  24 . If the suction cup has its bottom surfaces in engagement with a loaf of bread  22 , the sub-atmospheric pressure of the vacuum plenum  38  is applied to the loaf of bread and the loaf of bread will cling to the suction cup and will be movable in unison with the end effector  18 , as described above. Usually, the plugs will be closed and no air will flow through their suction cups when their suction cups are not being used to retrieve or hold a work product. 
     The plug actuator  48  may be driven by various power means, such as the application of pressure to a pneumatic cylinder  54 , or by solenoid actuation, or other mechanical means suitable for this purpose. Preferably, a pneumatic actuation system is desired for weight, simplicity of design and durability. 
     A valve bank unit  49  containing a valve for each plug actuator is mounted on or near the vacuum plenum housing and each valve is connected to one of the plug actuators  48  for controlling pressurized airflow to predetermined ones of plug actuators  48 . A conventional air pressure supply  53  is connected to the valve bank unit  49  for providing pressurized air through the valve bank unit to the conduits  51  leading from each valve of the valve bank unit to a fluid operated cylinder. The plug actuators  48  and valve bank unit  49  function as an air control means for operating the plugs  46 . 
     When the end effector  18  has not engaged a loaf of bread but has been charged with sub-atmospheric air pressure, all of the plugs  46  will be in their down positions engaging the upper structural portion of the suction cups, thereby blocking the air passages  42 . This prevents the dilution of the sub-atmospheric air pressure, maintaining the end effector in a charged condition, ready for picking the work product. Likewise, when the suction cups  24  in a predetermined zone of suction cups engage a work product for the purpose of picking the work product, the plugs  46  in the elected pick zone will be withdrawn from engagement with the air passage, allowing a stream of air to move from the suction cups up through the air passages  42 . If the product is engaged by the lower portion of the suction cups of the selected pick zone, the suction cups will draw a sub-atmospheric air pressure against the work product, causing the work product to cling to and be carried away by the suction cups. 
     As described above, once the first pick has been accomplished and the loaves of bread  22 A have been picked away from the accumulation of loaves at the delivery end of the surface conveyor, the vacuum plenum housing can be lifted, reoriented and reapplied to the accumulation of loaves, so that a different pick zone of suction cups  24  are applied to the accumulation of loaves, and the sub-atmospheric air pressure is created in the selected pick zone for the second pick of the work products. 
     Likewise, if subsequent picks are required, the process described above is repeated until the desired pattern of work products is accumulated by the suction cups of the end effector. 
     Because each suction cup is independently operated from the other suction cups, the user may prevent vacuum leakage through the suction cups that are not to engage a work product by closing the plugs  46  over the air passages  42  for any air passage whose underlying suction cup is not to fully engage with a work product  22 . Also, should some of the suction cups fully engage a work product  22  and the user does not desire to pick up that particular work product, the corresponding plug  46  and plug actuator  48  remain closed so that no sub-atmospheric air pressure is communicated to the suction cup. This results in no lifting or picking of the work product engaged by the suction cup that is out of the zone that is to pick the work products. 
     In the example shown in  FIGS. 4A and 4B , compressive surfaces  50  in the form of compression plates are mounted to the top wall  32  of the vacuum plenum housing  30  by support arm  52 . Fluid operated cylinder  54  and its rod  55  are pivotally supported by the support arm  52  and a pivotal connection  56 . When the fluid operated cylinder  54  expands to move its piston downwardly, the rod  55  moves the compression plates  50  downwardly and inwardly in the direction generally illustrated by arrow  58  so that the distal edges of the compression plates  50  become aligned with the perimeter walls and engage any surfaces of the work product that may be protruding laterally from beneath the suction cups  24 . This tends to gather and compress the picked products laterally inwardly beneath the suction surface  19  of the end effector. Preferably, the compression plates  50  will move to a position with respect to one another that will fit downwardly into the basket  20  ( FIG. 1A ). Similar compression plates are disclosed in my U.S. Pat. No. 7,017,961. 
       FIG. 5  is a flow chart depicting an example of a method of conducting multiple picks of bread loaves  22  with the end effector  18  and placing the retrieved bread loaves in a receptacle  20  in a desired configuration as shown in  FIG. 1B . As shown in block  65  of the flow chart, a user first sets the motion control means, such as a conventional programmed computer, to choose the desired configuration of the zones that correspond to the packaging pattern for the bread loaves and the receptacle. 
     In block  66 , bread loaves  22  are advanced by the surface conveyor  26  to its end stop  28  which is the position where the robot will place the end effector for picking the loaves. The end effector is moved to a position over the loaves at the end of the conveyor. 
     In blocks  67  and  68 , the end effector  18  is lowered so that the suction cups in the first pick zone engage the loaves as illustrated in  FIG. 3B , and upon activation of the suction cups, bread loaves  22 A are picked and the end effector  18  is lifted with the loaves  22 A in the first pick zone. 
     In blocks  69  and  70  of  FIG. 5 , bread loaves  22  proceed to accumulate at the end stop  28  of surface conveyor  26 , and the end effector  18  is shifted as indicated by  FIG. 3C  so that its second pick zone of suction cups will be lowered to retrieve and then lift the second pick of loaves  22 B. 
     In blocks  71  and  72  of  FIG. 5 , the end effector  18  is lifted and reoriented so that its third pick zone of suction cups will be aligned over the remaining loaves  22 C. In the meantime, block  73  shows that the loaves on the surface conveyor  26  will be advanced to the end stop  28 , at the desired position for being picked. 
     As indicated in block  74 , the end effector is lowered so that its third pick zone of suction cups is positioned over the work products at the end of the surface conveyor and the suction cups in this zone are activated so as to retrieve the remaining loaves. 
     Now that all of the pick zones of the end effector are occupied by loaves  22 , block  75  shows that the end effector is lifted, with all of the pick zones of suction cups retrieving the loaves, including loaves  22 C ( FIG. 3C ). 
     As shown in block  76 , the end effector is positioned over the receptacle, and in block  77  the end effector is lowered into registration with the basket or other receptacle, the suction cups are deactivated by opening the vacuum plenum housing  30  to the atmosphere which equalizes the air pressure from inside to the outside of the suction cups, thereby releasing the loaves inside the basket  20  ( FIG. 1A ). 
     At this point, the end effector is lifted away from the receptacle and returned to its ready position, as shown by block  78 . 
     The array of suction cups  24  is made in a dense pattern so that there will be a suction cup present in all positions that might engage a loaf of bread. There may be some instances where some of the suction cups in a pick zone are not actuated by forming a sub-atmospheric air pressure therein. The suction cups in a zone that are likely not to be used would be those that are to be placed at the adjacent edges of the work product, where the open ends of the suction cups may not become sealed against the work products. This unsealed situation may allow excessive air to enter through the open-ended suction cups into the vacuum plenum chamber, thereby depleting the vacuum in the chamber. This avoids the depletion of the vacuum in the chamber by inadvertently open suction cups. In the meantime, other suction cups in the pick zone would engage and lift the work products. 
     While this invention is disclosed as picking work products to fit within a basket or container, the invention may be used to place work products in or on other items that are not limited to a particular size or shape. Also, a layer of products in a particular pattern could be lifted all at once from a container and sequentially placed in a different reference configuration for the purpose of conveying the products away in a referenced configuration. 
     Although a preferred embodiment of the invention has been disclosed in detail herein, it will be obvious to those skilled in the art that variations and modifications of the disclosed embodiment can be made without departing from the spirit and scope of the invention as set forth in the following claims.