Patent Publication Number: US-10322888-B2

Title: End effector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application is a continuation of U.S. patent application Ser. No. 15/642,230 filed Jul. 5, 2017, issued Nov. 7, 2017 as U.S. Pat. No. 9,809,398, which is a continuation of U.S. patent application Ser. No. 15/058,066 filed Mar. 1, 2016, issued Aug. 15, 2017 as U.S. Pat. No. 9,731,913, which is a continuation of U.S. patent application Ser. No. 14/741,312, filed Jun. 16, 2015, issued Mar. 29, 2016 as U.S. Pat. No. 9,296,112, which is a continuation of U.S. patent application Ser. No. 14/536,653, filed Nov. 9, 2014, issued Jul. 7, 2015 as U.S. Pat. No. 9,073,022, which claims the benefit of U.S. provisional Application No. 61/904,418, filed on Nov. 14, 2013. The contents of the aforementioned application(s) are hereby incorporated herein by reference in their entirety as if set forth fully herein. Priority to, and/or the benefit of, each of the aforementioned applications is hereby expressly claimed in accordance with 35 U.S.C. §§ 119, 120, 365, 371 and/or any other applicable statutes. 
    
    
     BACKGROUND 
     The field of the invention generally relates to end effectors for picking and placing objects, and are typically used with robotic arms for picking up items off a conveyor belt and placing them in bulk packaging. 
     End effectors, also known as end-of-arm tools, in general are well-known in the art. In the packaging industry, an end effector is typically attached to the end of a robotic arm from a robot such as a Delta Robot. The robot controls the robot arm, which in turn controls movement of the end effector. The robot further includes a rotatable shaft to actuate an actuation mechanism of the end effector, to control movement of individual carrier assemblies. This is done typically to retrieve (pick) items (e.g., candy bars or other food items) from a first conveyor belt, and deliver (place) them into containers such as boxes on a second conveyor belt for retail distribution. 
     A typical end effector has carrier assemblies that each include a carrier block either fixed to the frame of the end effector, or slidingly engaged to the frame, with one or more pick-up members (typically suction cups) attached thereto and operatively connected to a vacuum source. The quantity and arrangement of the pick-up members may vary depending on the application. For example, an end effector designed to pick up two rows of 8 items each at a first diverged pitch, then place them into packaging in groups of 4 at a second pitch, is referred to herein as a 4×4, 4 by 4, or 4-4, since each side of the end effector would converge the items into 2 groups of 4 in preparation for placing them into the packaging, resulting in groups on each side of 4 and 4. 
     A first set of parameters associated with the items on the first conveyor belt are determined, such as their shape, dimensions, configuration, orientation, distance between each item, and distance between each group of items, and the first conveyor belt moves at a known speed. These parameters may be preset, programmed, and/or adjusted as needed. Likewise, the packages that receive the items are on a second conveyor belt, with a known second set of parameters that may differ from the first set of parameters. The end effectors are typically custom-designed to accommodate the parameters for a specific application. In this manner, the robot and end effector may be programmed and designed to pick up items at a first pitch and place them into packaging at a second pitch as required. 
     In order for the pick-up members to pick up items at a first pitch, and place them into a package at a second pitch, the pick-up members must be moveable. Various end effector designs are known for doing so. For example, some earlier successful designs, such as those manufactured by Demaurex, connect (via a connector) to the robot arm, and also have a spindle operatively connected to a rotatable shaft of the robot. The end of the shaft attached to the end effector is attached to a rotary rack and pinion actuation mechanism associated with the end effector, with arms extending out from the pinion attached to carrier blocks on either side of the end effector. As the robot rotates the shaft, the pinion thus rotates, causing the arms to move accordingly, which in turn causes the carrier blocks with the pick-up members to move longitudinally along the body of the end effector.  FIGS. 12-13  are selected pages of a Demaurex manual from the year 2000, illustrating several views of the Demaurex end effector with the connector, rack, and pinion annotated. In the Demaurex device, the pick-up members are all directly connected to the arms, and thus move in synch with the arms. 
     Another known design uses a rotary cam and cam blocks instead of a rack and pinion. See, e.g., U.S. Pat. No. 7,390,040 (Subotincic), the contents of which are incorporated herein by reference. Subotincic describes having only certain pick up members directly connected to the actuation mechanism. Other pick up members are indirectly connected to the actuation mechanism, and are moved by the directly-connected pick-up members by way of tie links. The tie links are small plastic pieces often dangling (not fixed) from the bottom of the end effector and move at high speeds. Also, access to the rotary mechanism is difficult in the Subotincic design, making installation, repair, and maintenance challenging at times. 
     SUMMARY 
     In one embodiment, the present invention is directed to an end effector comprising a frame, a bridge, a rack assembly, a pinion assembly, and a spindle assembly (collectively, the rack assembly, pinion assembly and spindle assembly referred to as a rack and pinion assembly), actuation rods, carrier assemblies, and vacuum ports. The rack and pinion assembly has a robot interface configured to be operatively connected to a robot&#39;s rotatable shaft, and an actuation interface operatively coupled to the actuation rods. The actuation rods are fixedly connected to one or more of the carrier assemblies. Thus, as the robot&#39;s shaft rotates about its axis, the rack and pinion assembly is actuated, which in turn actuates the actuation rods, which causes the carrier assemblies fixedly connected to the actuation rods to move longitudinally along the frame. 
     In one aspect of the present invention, less than all of the carrier assemblies are directly connected to the actuation rods. The carrier assemblies directly connected to the actuation rods are referred to as “directly connected” carrier assemblies and the carrier assemblies not directly connected to the actuation rods are referred to as “non-connected” carrier assemblies or “indirectly connected” carrier assemblies. Cooperating members on each of the carrier assemblies are used to couple the non-connected carrier assemblies to the directly connected carrier assemblies such that the movement of the directly connected carrier assemblies causes movement of the non-connected carrier assemblies. In one embodiment, the cooperating members are arms having grabbers. Each carrier assembly includes a carrier block and at least one pick-up member. Each carrier block has one or more arms extending towards an adjacent carrier assembly. Each arm has a grabber to cooperate with the grabber of the adjacent carrier block of the same subgroup, wherein during movement in the direction of divergence of the carrier assemblies the adjacent grabbers move into contact with each other and the grabbers engage such that first carrier assembly of the adjacent carrier assemblies pulls the other carrier assembly in the direction of movement of the first carrier assembly until at their full travel they lock into position at full divergence. During movement in the direction of convergence of the carrier assemblies, the grabbers disengage and glide along the surface of their adjacent arms and/or through slots in the openings of the adjacent carrier blocks until full convergence is achieved. At full convergence, the carrier blocks typically abut, either by side walls or by detents or tabs, such that movement of a first carrier assembly of the adjacent carrier assemblies pushes the other carrier assembly in the direction of movement of the first carrier assembly. Thus as the carrier assemblies fixedly connected to the actuation rods move longitudinally along the frame, adjacent carrier members in the same subgroup are moved as described herein. 
     In additional aspects of the present invention, the rack assembly may comprise rack rails fixedly mounted to the bridge with each rack rail having a rack slidingly engaged with the rack rail. The end effector may also include a robot interface in the form of a connector plate configured to be couple the end effector to a robot. The end effector may also include one or more vacuum ports for connecting the end effector to a vacuum source for applying a vacuum to the pick-up members of each of the carrier assemblies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a bottom perspective view of an end effector with the carrier assemblies in a diverged position, according to one embodiment of the present invention; 
         FIG. 2  is a bottom perspective view of the end effector of  FIG. 1 , with the carrier assemblies in a converged position, according to one embodiment of the present invention; 
         FIG. 3  is a top perspective view of the right side of the end effector of  FIG. 1 , with the carrier assemblies in a converged position, according to one embodiment of the present invention; 
         FIG. 4  is a top perspective view of the right side of the end effector of  FIG. 1 , with the carrier assemblies in a diverged position, according to one embodiment of the present invention 
         FIG. 5  is bottom view of the end effector of  FIG. 1 , according to one embodiment of the present invention; 
         FIG. 6  is an enlarged, partial bottom view of the end effector of  FIG. 1 , with the carrier assemblies in a partially diverged position according, to one embodiment of the present invention; 
         FIG. 7  is an enlarged, partial, bottom perspective view of the end effector of  FIG. 1 , with the carrier assemblies in a diverged position, according to one embodiment of the present invention; 
         FIG. 8  is an enlarged partial, bottom perspective view of the end effector of  FIG. 1 , with the carrier assemblies in a partially converged position, according to one embodiment of the present invention; 
         FIG. 9  is an enlarged partial, exploded, side view of the end effector of  FIG. 1 , according to one embodiment of the present invention; 
         FIG. 10  is an enlarged partial, exploded, side perspective view of the end effector of  FIG. 1 , according to one embodiment of the present invention; 
         FIG. 11  is an enlarged, partial, perspective side view of the end effector of  FIG. 1  showing the pinion assembly removed, according to one embodiment of the present invention, according; 
         FIGS. 12A, 12B and 12C  illustrate an alternative embodiment of carrier assemblies, according to another embodiment of the present invention. 
         FIG. 13  illustrates several views of a subassembly of a prior art Demaraux end effector. 
         FIG. 14  illustrates several views of another subassembly of a prior art Demaraux end effector. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention comprises an end effector comprising a rack and pinion assembly having a robot interface configured to be operatively connected to the robot&#39;s rotatable shaft at one end, and an actuation interface configured to operatively connect to actuation rods at the other end. The actuation rods are fixedly connected to one or more carrier assemblies, such that the carrier assemblies move in synch therewith. Other carrier assemblies may be indirectly connected to an actuation rod, (i.e., they move not in synch therewith), or fixed to a frame of the end effector. The carrier assemblies each have at least one pick-up member configured to pick-up an object, such as by using a controllable vacuum to grasp an object, and then place the object, such as by releasing the vacuum. The carrier assemblies are movable relative to the overall end effector so that the carrier assemblies can be arranged to in a first pattern (e.g. pitch or spacing) pick-up a plurality of objects in the first pattern (e.g. pitch or spacing), and then be moved to a second pattern (e.g. pitch or spacing) to place the plurality of objects in the second pattern. Typically, the entire end effector is also moved by a robot between a first location to pick-up the objects and a second location different from the first location to place the plurality of objects. 
     Referring to  FIGS. 1-8 , one embodiment of an end effector  10  according to the present invention is shown. The end effector  10  comprises a frame  12  to which a plurality of carrier members  14  are slidingly (or otherwise movably) engaged to frame  12 . The frame  12  may be constructed from a lightweight aluminum or other metal, or other suitable material such as carbon fiber composites, fiberglass, etc. In this described embodiment, the frame  12  is an elongate, hollow tube having a substantially rectangular cross-section. The hollow tube structure forms an air flow passageway through the frame which allows the frame  12  to also function as a manifold and conduit for the vacuum air flow between a vacuum source, and the various vacuum ports and other vacuum manifolds on the end effector  10 , as described below. The external surface of the frame  12  has a frame groove  11  to slidingly engage a frame guide  66  of each of the carrier assemblies  14  to slidingly couple the carrier assemblies  14  to the frame  12 . 
     A bridge assembly  16  is attached to a top surface of the frame  12 . The bridge assembly may be a single, integral structure, or as is shown in this exemplary embodiment, an assembly of multiple pieces connected together. The bridge assembly  16  may be constructed of any of the same materials as the frame  12 , as described above. As better shown in  FIGS. 3-4 , the bridge assembly  16  is comprised of a flat top plate  18 , and two side supports  20  connected to the top piece at opposing ends of the top piece  18 . The side supports  20  each include a vertical support  22  and a lateral support  24  to provide structural integrity. The top plate  18  and side supports  20  may have holes in their surfaces to reduce weight while not compromising structural integrity. 
     The bridge assembly  16  is attached to the frame at multiple stress points using any suitable fastening device, such as screws, rivets, hex-bolts, bolts, welding, or other suitable means, thereby providing vertical support and lateral support to the connection between a connector plate  26  of a robot (now shown) and the end effector  10 . The connector plate  26  may be bolted to machined screw holes in the top plate  18  of the bridge assembly  16  using the bolts  28 . This provides the structural strength required during high-speed operation of the end effector  10 . 
     The bridge assembly  16  has an opening  32  (see  FIG. 10 ) in the top plate  18  to allow a spindle assembly  52  of a rack and pinion assembly  50  to pass vertically through the opening  32 . The opening  32  may be substantially circular, or have at least a semi-circular portion. As described in more detail below, the spindle assembly  52  couples a pinion assembly  54  to the robot&#39;s rotatable shaft thereby transferring rotation of the robot&#39;s rotatable shaft to rotate the pinion assembly  54 . The bridge assembly  16  also has an access opening  30  in the form of a frontal cutout  30  in the top plate  18  configured to allow the spindle assembly  52  to pass horizontally through the access opening  30 , typically while still attached to the pinion assembly  54 . The access opening  30  allows easy access for installation, repair and maintenance of the rack and pinion assembly  50  without having to further disassemble the end effector  10 . The access opening  30  is wide enough to allow the spindle assembly  52  (which is typically cylindrical) to pass through the access opening, and still provide some leeway for manual installation and removal of the spindle assembly  52 . 
     The bridge assembly  16  has a plurality of rail supports  36  (also referred to as rail braces) for securing rack rails  38  in place, one on the front side and one on the back side of the bridge assembly  16 . The rail supports  36  may be formed as part of the side supports  20 , as shown in the exemplary embodiment, or they may be separate parts fastened to the bridge assembly  16 . The rack rails  38  may be attached to the rail supports  36  using any suitable fastening means, such as screws, bolts, rivets, press-fitting, welding, etc. 
     The bridge assembly  16  houses the pinion assembly  54 . The access opening  30  and the height of the top plate  18  above the frame  12  are configured to provide sufficient space to allow the pinion assembly  54  and spindle assembly  52  to be installed and removed through this space without further disassembly of the end effector or separating the pinion assembly  54  from the spindle assembly  52 . 
     The end effector  10  may also include various vacuum ports located at strategic positions on the frame  12  to connect an air vacuum source to the end effector  10  and to connect each of the carrier assemblies  14  to the vacuum air flow. A pair of input vacuum ports  40  are mounted on a top surface of the frame  12 , one towards each end of the elongate frame  12 . The input vacuum ports  40  are mounted on the frame  12  over an opening into the frame  12  such that input vacuum ports  40  are in fluid communication with the passageway in the frame  12 . The input vacuum ports  40  are configured to be connected to a vacuum source, such as vacuum source tubing connected to a vacuum source, for providing a vacuum air flow to the end effector  10 . A plurality of distribution vacuum ports  42  are mounted at spaced locations on a side surface of the frame  12 , such as a group of three distributions vacuum ports  42  at each end of the frame  12 . The groups of distribution vacuum ports  42  may be integrally formed into a distribution vacuum manifold with ports  43 , as shown in the exemplary embodiment, or they may be separate structures. Each distribution vacuum port  42  is configured to be connected via tubing (not shown) to a carrier vacuum port  44  on the carrier assemblies  14 . Accordingly, an overall vacuum air flow path through the end effector  10  is formed, commencing at the pick-up members  15 , into the carrier blocks  17  and out of the carrier vacuum port  44 , then through the tubing to the distribution vacuum ports  42 / 43 , then into and through the passageway in the frame  12 , then through the input vacuum ports  40 , and finally through the source tubing to the vacuum source. The vacuum ports  40  and  42  may be formed of any suitable material, such as polymers, nylon, plastic, composites, etc. The vacuum ports  40  and  42  may be of varying sizes, configurations, interfaces, and orientations, and they may have multiple connections connected through a single part and/or manifold. For instance, the input vacuum ports  40  may be ¾ inch ports, and the distribution ports  42  may have multiple (such as three) ¼ inch ports. The carrier vacuum ports  44  are preferably the same size as the distribution ports  42  (in this example, ¼ inch ports) so that the same size tubing can connect between them. 
     Turning to  FIGS. 9-11 , the rack and pinion assembly  50  includes a pinion assembly  54  and a mating rack assembly. Referring also to  FIGS. 1-5 , the rack assembly includes the left side rack assembly  34   a  and the right side rack assembly  34   b . Each rack assembly  34  includes a rack rail  38  and a corresponding rack  35  slidingly coupled to the rack rail  38 . Each rack rail  38  is fixedly attached to the corresponding rail supports  36  of the bridge assembly  16 . Each rack  35  has an elongated portion with vertically aligned teeth along its inside surface (surface facing the pinion  56 ) and a substantially smooth outside surface (surface facing and engaging the rack rail  38 ). The outside surface of each rack  35  is slidingly coupled to its corresponding rack rail  38 , using any suitable means. For example, nylon or other lightweight spacer may be extruded and attached to the outside surface of the rack  35 , to slide within a mating extruded or machined slot in the inside surface (the surface facing the rack  35 ) of rack rail  38 . The spacers may be attached to the racks  35  by any suitable means, such as screws, bolts, rivets, glue, etc. 
     Each rack  35  has at least one rack brace  46  extending downward from the bottom of the rack  35  and having a mounting sleeve fixedly attaching the rack brace  46  to a corresponding actuation rod  48 , with one actuation rod  48  for each rack  35 . The actuation rod  48  fits into the mounting sleeve and a set screw is used to fix the mounting sleeve in place on the actuation rod  48 . The rack brace  46  may be integrally molded as part of the rack  35 , or it may be a separate part attached to the rack  35 , such as by a press fit, bonding, fasteners, or other suitable means of attachment to the rack  35 . 
     The rack rails  38  may be constructed of aluminum or other lightweight metal, or other suitable material. Each rack rail  38  is secured in place by attachment to its corresponding rail support(s)  36  on the bridge assembly  16 . The rack rails  38  may be alternatively, or additionally, secured to the frame  12 . 
     Referring again to  FIGS. 9-11 , the pinion assembly  54  includes a pinion  56 , a pinion cover  58 , and a spindle assembly  52 . The pinion  56  is a substantially circular toothed gear, with teeth arranged vertically to mate with the teeth on the racks  35 . The pinion  56  may be made of any suitable material, preferably the same as that used for the racks  35 . The teeth on the pinion  56  may be colored at various arcs. For example, first and second colors may be used to color the teeth (and/or upper surface of the pinion) every other x degrees (where x is 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, etc.), or each sector may have a unique color. This may be helpful during maintenance to allow a technician to rotate and reposition the pinion a certain amount so as to allow previously-unengaged sectors of teeth to be positioned in a manner to engage the racks  35  during operation, and likewise the previous sectors of teeth that engaged the racks  35  during operation will be rotated to non-engaging positions. This provides for more uniform wear of the pinion  56 , and a longer operating life. 
     The pinion  56  is positioned to be rotatably engaged between the left side rack  35  (on the left rack assembly  34   a ) and the right side rack  35  (on the right rack assembly  34   b ) during operation, with teeth rotatably mating with the teeth of the racks  35 . The racks  35  and pinion  56  may be made of material similar to the vacuum ports  40  and  42 . 
     The pinion  56  may have a protective pinion cover  58 , as seen in  FIGS. 9 and 11 , which assists in keeping the pinion  56  engaged with the racks  35  during operation. The pinion cover  56  may have top surface cutouts sufficient for venting of heat and minimizing weight, without compromising functionality, and frontal cutouts to allow visual inspection of the pinion  56  during operation of the end effector  10 . The pinion cover  58  may be made of a material similar to that used for the vacuum ports  40  and  42 , the carrier blocks  17 , the racks  35 , and/or the pinion  56 . 
     The rack and pinion assembly  50  functions differently than that of the Demaurex design shown in  FIGS. 13 and 14 , because some of the carrier assemblies  14  in the present design are not directly connected to the actuation rods  48 , but instead are either fixed (e.g., bolted or riveted to the frame) or moved by grabbers  21  of adjacent carrier assemblies  14 , as described in more detail below. 
     The spindle assembly  52  has a housing and a rotatable shaft configured to rotate within the housing. The rotating shaft has a bottom end operatively connected to the pinion  56 . The top end of the rotatable shaft can be operatively connected to a mating rotatable shaft of the robot. The top end of the housing is configured to fixedly connect to the connector plate  26 , for example, by threaded mating portions. The spindle assembly  52  may be custom-machined or altered from the off-the-shelf spindle typically accompanying the robot, to accommodate specific applications. Although the spindle assembly  52  is considered part of the pinion assembly  54  as described herein for convenience, it may also be considered a separate component. 
     Thus, the rack and pinion assembly  50  allows a rotational force applied to the rack and pinion assembly  50  through the shaft of the spindle assembly  52  to be translated into linear longitudinal motion of the racks  35  and attached actuation rods  48 . Each of the actuation rods  48  is fixedly connected to one or more directly-connected carrier assemblies  14  to directly move the directly connected carrier assemblies  14  when the actuation rods  48  are actuated by the rack and pinion assembly  54 . The directly-connected carrier assemblies are connected to a corresponding actuation rod  48  using a carrier mounting sleeve  60  which fixedly attaches to the actuation rod, similar to the mounting sleeve of the rack brace  46 . A set screw may be used to fix the mounting sleeve  60  in place on the actuation rod  48 . Accordingly, the actuation rod  48  on the left side of the end effector  10  is directly connected to, and actuates, directly-connected carrier assemblies  14   a  and  14   e  (see  FIG. 4 ). The actuation rod on the right side of end effector  10  is directly connected to, and actuates, directly-connected carrier assembles  14   d  and  14   h . which are directly connected to the is connected by a rack brace to the rack on its side of the end effector, to cause movement of the rod when the rack is actuated. Thus, when the robot shaft rotates the shaft of the spindle assembly  52  which rotates the pinion  56 ; the rotation of the pinion  56  actuates the racks  35  causing linear translation motion of the racks  35  in opposite directions (i.e. the left side rack moves in the opposite direction of the right side rack), which in turn causes linear motion of the actuation rods  48  (also in opposite directions from each other), which causes the directly connected carrier assemblies  14   a ,  14   e ,  14   d  and  14   h  to move in synch therewith (with carrier assemblies  14   a  and  14   e  moving in a first direction and carrier assemblies  14   d  and  14   h  moving in the opposite direction). The actuation rods  48  may be made of lightweight metal or other suitable material, similar to the material used for the frame  12  and bridge  16 . 
     Referring to  FIGS. 6, 7 and 8  (and also  FIGS. 1-4 ), each carrier assembly  14  includes a carrier block  17  and at least one pick-up member  15  attached to a pick-up housing  64  on the bottom of the carrier block  17 . In the exemplary embodiment, each carrier assembly  14  includes two pick-up members  15 , one for the right side of the end effector  10  and one for the left side of the end effector  10 . The pick-up housing  64  includes an aperture for receiving a flanged portion of each of the pick-up members  15  to securely, and removably, attach the pick-up members  15  to the carrier block  17 . Each carrier block  17  has a carrier vacuum port  44  disposed at a top end of the carrier block  17 . Each carrier block  17  has an carrier block passageway providing an airflow path from each of the pick-up members  15  to the carrier vacuum port  44 . 
     Each of the carrier blocks  17  also has at least one arm  19  having a grabber  21  (or catch) extending longitudinally toward the adjacent carrier block(s)  17 . The carrier assemblies  14  of the end effector  10  are configured in subgroups which are coupled together by the arms  19  to be moved in cooperation with each other by the actuation of the actuation rods  48 . For example, in the exemplary end effector  10 , carrier assemblies  14   a ,  14   b ,  14   c  and  14   d  are configured in a left subgroup (left per the orientation of  FIG. 5 ) and carrier assemblies  14   e ,  14   f ,  14   g  and  14   h  are configured in a right subgroup (again, right per the orientation of  FIG. 5 ). The end positioned carrier assemblies  14  (including  14   a ,  14   d ,  14   e  and  14   h ) of a subgroup have carrier blocks  17  each having a single arm  19  extending either right or left toward the adjacent carrier block  17 . For instance, carrier block  17  of carrier assembly  14   a  is on the left end of the left subgroup, and it has a single right arm  19  to cooperate with a left arm  19  extending from the adjacent carrier block  17  of carrier assembly  14   b . The internal carrier assemblies  14  have an adjacent carrier assembly  14  on both the left side and right side (e.g.  14   b ,  14   c ,  14   f  and  14   g ). Each of the carrier blocks  17  of the internal carrier assemblies has a left arm  19  and a right arm  19  with grabbers to cooperate with the arms  19  of adjacent carrier blocks  17  of the same subgroup on each side. In other words, each carrier block  17  (other than those on the end of a pick-and-place subgroup) includes a right arm extending laterally therefrom towards its adjacent carrier block  17  to the right, and a left arm  19  extending laterally therefrom towards its adjacent carrier block  17  to the left, except those carrier blocks  17  on the end of a sub-group have only one arm  19 , extending towards their only adjacent carrier block  17 . Each arm  19  may be a single extending piece as seen in  FIGS. 1-11 , two extending pieces as seen in  FIGS. 12A-12C , or multiple extending pieces (not shown). The arms  19  and grabbers  21  are configured such that when a directly-connected carrier assembly  14  and its arm  19  with grabber  21  moves laterally away from a cooperating arm  19  with grabber  21  of an adjacent cooperating carrier assembly  14  (which is a non-connected carrier assembly as configured on end effector  10 ) in the same subgroup, the moving arm  19  with grabber slides along the cooperating arm with grabber  21  until the moving grabber  21  bears against the cooperating grabber  21 , and then the moving arm  19  with grabber  21  pulls the cooperating arm with grabber  21  (and its corresponding carrier assembly  14 ) in the direction of the moving arm  19  with grabber  21 . This describes the actuation when the carrier assemblies  14  are being actuated in a diverging motion from a converged position (see  FIGS. 2, 3, 5, 6 and 8 ) to a diverged position (see  FIGS. 1, 4, and 7 ). When the directly-connected carrier assembly  14  is moved in the opposite direction (i.e. from the diverged position shown in  FIGS. 1, 4 and 7  to the converged position shown in  FIGS. 2, 3, 5, 6 and 8 ), the moving arm  19  with grabber  21  of the directly-connected carrier assembly  14  slides along the cooperating arm  19  with grabber  21  of the non-connected carrier assembly  14 . As the moving arm  19  with grabber  21  and the cooperating arm  19  with grabber approach the respective adjacent carrier blocks  17 , the moving arm  19  with grabber  21  advances into the slot  62  of the cooperating carrier block  17  and the cooperating arm  19  with grabber  21  advances into the slot  62  of the moving carrier block  17  until the moving carrier block  17  contacts the cooperating carrier block. This position of the carrier assemblies is shown in  FIGS. 5 and 6 , and may be considered the converged position, or alternatively, a partially converged position, depending on the desired pitch in the converged position. Continued movement of the moving carrier block  17  pushes the cooperating carrier block  17  to a further converged position, until the cooperating carrier block  17  contacts the adjacent carrier block  17  on side opposite the moving carrier block  17 , in which case, a fully converged position of the carrier assemblies  14  is attained. 
     The carrier blocks  17  may be constructed of material same or similar to the racks  35  and pinion  56 . Each carrier block  17  may be molded as a single-piece, including the body, arms  17 , grabbers  19 , and pick-up-member housing  64 . Each carrier block  17  hosts one or more pick-up members  15  (e.g., suction cups). The carrier blocks  17  are slidingly engaged with the frame  12  and configured for longitudinal sliding movement along the frame  12 . However, in some embodiments, some carrier assemblies  14  may be fixed to the frame  12  for specific applications such that those fixed carrier assemblies  14  do not move relative to the frame  12 . Each arm  19  has a grabber  21  configured to hook onto the grabber  21  of an arm from its adjacent carrier block  17 . The grabbers  21  may be in the form of oppositely oriented fingers at the end of the arms  19 , as seen in the figures, for instance  FIGS. 7 and 8 . For example, the grabber  21  on the arm  21  of one carrier block  17  may be pointed vertically upward, while the grabber  21  on the arm  19  of an adjacent carrier block  17  may be pointed vertically downward, as seen in  FIGS. 7 and 8 . 
       FIGS. 7 and 8  show a side view of the end effector  10  and the carrier assemblies  14 . The carrier vacuum ports  44  on each of the carrier blocks  17  can be seen. The carrier blocks  17  each have a frame guide  66  which is slidingly received in the frame groove  11  to slidingly couple the carrier assemblies  14  to the frame  12 . The carrier blocks  17  each have a carrier slot  62  above the pick-up member housing  64  just below the frame guide  66 . The carrier slot  62  is configured to receive the arm(s)  19  of adjacent carrier blocks  17  during convergence. The arms  19  of the internal carrier blocks  17  are offset such that the right arm and left arm of the carrier block offset, i.e., one extends from the front of the slot and one extends from the back of the slot. (“Front” and “back” are used as relative terms relative to the “right” and “left” terms used to describe the direction of movement of the carrier blocks longitudinally along the frame, corresponding to the “right” and “left” arms of the carrier blocks.) The offset allows two arms  19  to be received in the carrier slot  62  at the front—one from the carrier block  17  itself, and one from an adjacent carrier block  17 —and two arms  19  to be received in the slot at the back—one from the carrier block  17  itself, and one from an adjacent carrier block  17 , during convergence. Similarly, arms  19  on one carrier block  17  extend outward (left and/or right) from the roof or upper edge of the carrier slot  62 , whereas the arms  19  of an adjacent carrier block  17  in the same subgroup extend outward from the floor or bottom of the carrier slot  62 . This further allows the cooperating arms  19  to glide or slide over/under each other during convergence and divergence, as seen in  FIGS. 7 and 8 . 
     The carrier assemblies  14  are positioned for pick and place based on programming of the robot according to the position of the pick and place objects in the “pick” position and the “place” position. Typically, the “pick position” has the objects in a uniform array, such as in the present example, two rows of objects with each row spaced at the diverged spacing of the carrier assemblies  14  (see  FIGS. 1, 4 and 7 ). The “place” phase of the pick-and-place operation requires the carrier assemblies  14  (with items secured to the pick-up members) to be positioned into subgroups, typically at a pitch smaller than (or otherwise different from) that at which the pick-up members “picked” the items. Thus, the “place position” may have two subgroups of 4 on each side of the end effector  10 , in which the rows are spaced at the converged spacing of the carrier assemblies  14  (see  FIGS. 2, 3, 5, 6 and 8 ). For example, if the items are to be placed in 2 groups of 4, the carrier assemblies  14  will be positioned such that each side of the end effector  10  (right and left) has 2 subgroups of 4 pick-up members each (referred to herein as 4×4, 4 by 4, or 4-4). 
       FIGS. 12A, 12B and 12C  show an alternative configuration for carrier blocks  17   a  using arms  19   a  instead of the arms  19  described above. The arms  19   a  include multiple extension arms and grabbers  21  instead of the single arm  19  and grabber  21 , of the carrier blocks  17  described above. Otherwise, the carrier blocks  17  are the same or substantially similar to the carrier blocks  17 , the description above applies equally to the carrier blocks  17 , where applicable.  FIG. 12A  shows the carrier assemblies  14  as separate parts.  FIG. 12B  shows the carrier assemblies  14  in a diverged position with the grabbers  21  in an engaged position.  FIG. 12B  shows the carrier assemblies  14  in a partially converged position with the grabbers  21  disengaged and the arms  19   a  extending into the carrier slots  62  of the adjacent carrier blocks  17 . 
     The operation of the end effector  10  will now be described with reference to the figures. It is understood that the end effector  10  is to be attached to a robot by attaching an interface member of the robot to the connector plate  26 , and connecting the robot&#39;s rotatable shaft to the top end (robot shaft interface) of the spindle shaft of the spindle assembly  52  of the rack and pinion assembly  50 . A vacuum source is also connected to the input vacuum ports  40  using suitable tubing. In addition, tubes (not shown) are connected between the distribution vacuum ports  42  and each of the carrier vacuum ports  44  of the carrier assemblies  14 . The robot is activated and controls the movement of the entire end effector  10 , as well as controlling the position of the carrier assemblies  14  by controlling the position of the spindle shaft via the position of the robot&#39;s rotatable shaft). 
     Starting with the carrier assemblies  14  in the diverged position as shown in  FIG. 1 , the robot positions the end effector  10  over the objects to be picked up with each of the pick-up members  15  above and/or against the objects to be picked. The robot activates the vacuum source (such as be opening a valve) which creates a vacuum at each of the pick-up members  15  via vacuum air flow through the pathway as described above. The vacuum at each of the pickup members  15  causes the objects to be picked up by the pick-up members, and then the robot moves the end effector  10  to a place location where the picked up objects will be placed. While the end effector  10  is being moved and/or when it reaches the place location, the robot actuates the end effector  10  to move the carrier assemblies  14  to a converged position for placing the objects at the desired pitch. 
     Referring to  FIG. 1 , the robot rotates the robot&#39;s rotatable shaft in a clockwise direction (looking down on the end effector  10 ), thereby rotating the spindle shaft and the pinion  56  in a clockwise direction. The clockwise rotation of the pinion gear drives the racks  35  to move linearly, with the left rack  35  moving backward (into the page according to the orientation of  FIG. 1 ) and the right rack  35  moving forward (out of the page according to the orientation of  FIG. 1 ). The movement of the racks  35  cause the actuation rods  48  to move in the same direction as their corresponding rack  35 , which causes the directly connected carrier assemblies  14   a ,  14   e ,  14   d , and  14   h  to move in synch with their corresponding actuation rods  48 . In other words, carrier assemblies  14   a  and  14   e  move backward towards their corresponding adjacent carrier assemblies  14   b  and  14   f , respectively; and carrier assemblies  14   d  and  14   h  move forward towards their corresponding adjacent carrier assemblies  14   c  and  14   g , respectively. 
     Depending on the desired pitch for the place position, the robot&#39;s shaft may actuate the movement of the carrier assemblies  14  to the position where the directly connected carrier assemblies  14  just come into contact with the non-connected carrier assemblies  14  as shown in  FIGS. 5, 6 and 8 , or it may actuate them into a further converged position in which the directly connected carrier assemblies  14  bear against the non-connected carrier assemblies  14  and move them to a further converged position, as shown in  FIGS. 2 and 3 . When the end effector  10  is positioned in the place position and the carrier assemblies  14  are actuated to the desired place pitch, the robot de-actuates the vacuum (such as by closing a valve to the vacuum source), causing the pick-up members  15  to release the objects at the place position. 
     The robot then moves the end effector  10  to a position to pick up more objects, and at the same time moves the carrier assemblies  14  back to the diverged position. The robot rotates the robot&#39;s rotatable shaft in a counter-clockwise direction (looking down on the end effector  10 ), thereby rotating the spindle shaft and the pinion  56  in a counter-clockwise direction. The c counter-clockwise rotation of the pinion gear drives the racks  35  to move linearly, with the left rack  35  moving forward (out the page according to the orientation of  FIG. 1 ) and the right rack  35  moving backward (out of the page according to the orientation of  FIG. 1 ). The movement of the racks  35  cause the actuation rods  48  to move in the same direction as their corresponding rack  35 , which causes the directly connected carrier assemblies  14   a ,  14   e ,  14   d , and  14   h  to move in synch with their corresponding actuation rods  48 . In other words, carrier assemblies  14   a  and  14   e  move forward away from their corresponding adjacent carrier assemblies  14   b  and  14   f , respectively; and carrier assemblies  14   d  and  14   h  move backward away their corresponding adjacent carrier assemblies  14   c  and  14   g , respectively, until the carrier assemblies are position in the desired diverged position for the pick position. The process may then be repeated as required. 
     The end effector  10  may also be configured to work in connection with other actuation mechanisms and/or other carrier movement mechanisms besides the rack and pinion actuation mechanism, including rotary cams and cam blocks and/or tie links, as described, e.g., in Subotincic, which is incorporated by reference above. 
     Although particular embodiments have been shown and described, it is to be understood that the above description is not intended to limit the scope of these embodiments. While embodiments and variations of the many aspects of the invention have been disclosed and described herein, such disclosure is provided for purposes of explanation and illustration only. Thus, various changes and modifications may be made without departing from the scope of the claims. For example, not all of the components described in the embodiments are necessary, and the invention may include any suitable combinations of the described components, and the general shapes and relative sizes of the components of the invention may be modified. Accordingly, embodiments are intended to exemplify alternatives, modifications, and equivalents that may fall within the scope of the claims. The invention, therefore, should not be limited, except to the following claims, and their equivalents.