Docking station

[0002] This application claims the benefit of U.S. Provisional Application No. 60/124,427 filed Mar. 15, 1999.

[0003] The present invention relates to systems and devices used to load containers and pallets. More particularly, the present invention relates to a docking station used to position and detect the presence of carts and pallets that are loaded with objects of interest by a robotic system.

[0004] Robotic systems are used to accomplish a wide variety of tasks. Recently, robotic systems have been designed to load mail trays and tubs of different shapes and sizes on pallets and into wheeled containers and carts. Often, the process of loading articles into carts and onto pallets is generically referred to as “containerization.” In broad terms, the process involves grouping many loose items into “containers” so that the items may be shipped to desired destinations.

[0005] To successfully accomplish containerization, it is best if the location and type of container is known or may be readily determined by the robotic system. Knowing the location of the container is important because the location is used by the robotic system to determine where to place articles it is handling. Knowing the type of container is important because such information is generally used by the robotic system to determine how to place articles on or in the container.

[0006] In the past, simple sensors have been used to detect the absence or presence of carts at a “drop-off” location. In addition, some robotic systems have used mechanical guides to help position carts at exact locations. However, a docking station having both mechanical and sensor capability to position and detect multiple types of containers (e.g., carts and containers) has not been developed.

[0007] The invention provides a docking station for a robotic mail tray loading system. The docking station includes a ground plate that is mounted to the floor of the building in which the robotic mail tray loading system is housed. The ground plate has first and second wheel-retaining recesses that preferably include ramped surfaces to accommodate wheels of mail carts. Welded or otherwise mounted to the ground plate is a plurality of guide plates. Preferably, the guide plates are positioned to locate one pallet or two mail carts in the docking station at a time.

[0008] The docking station also includes a plurality of sensors. Preferably, the docking station includes a pallet sensor that senses the presence or absence of a pallet in the docking station. The docking station also preferably includes first and second cart presence sensors which determine the presence or absence of first and second mail carts, respectively, in the docking station. The docking station also preferably includes first and second cart type sensors paired with the first and second cart presence sensors, respectively, to determine the type of the first and second carts, respectively.

[0009] Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.

[0010] FIG. 1 is a simplified schematic view of a robotic mail tray loading system including a plurality of docking station sensors embodying the present invention.

[0011] FIG. 2 is a schematic view of the junction box and docking station sensors of FIG. 1.

[0012] FIG. 3 is a perspective view a docking station embodying the invention.

[0013] FIG. 4 is a top view of the docking station of FIG. 3.

[0014] FIG. 5 is a top view of a plurality of docking stations embodying the present invention.

[0015] FIG. 6 is a side view of the docking stations of FIG. 5.

[0016] FIG. 7 is an enlarged cross-sectional view taken along line 7—7 in FIG. 5.

[0017] FIG. 8 is an enlarged cross-sectional view taken along line 8—8 in FIG. 5.

[0018] Before embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of “consisting of” and variations thereof herein is meant to encompass only the items listed thereafter. The use of letters to identify elements of a method or process is simply for identification and is not meant to indicate that the elements should be performed in a particular order.

[0019] FIGS. 1 and 2 illustrate a robotic system 10 used to load mail tubs and trays (generically referred to herein as “trays”) on pallets and wheeled mail carts (pallets and carts collectively referred to herein as “containers”). As is schematically shown, the system 10 includes a controller 14, a junction box 18, a plurality of docking station sensors 22, and a robot 26. The controller 14 is wired through an electrical, fiber optic, or other suitable conduit 30 to the robot 26, and controls the operation thereof. With particular reference to FIG. 2, each docking station 31 includes a pallet sensor 34, first and second cart presence sensors 38, 42, and first and second cart type sensors 46, 50. (Generically, the cart presence and cart type sensors are referred to as “detection sensors.”) Each sensor 34, 38, 42, 46, 50 is wired to the junction box 18 with an electrical, fiber optic, or other suitable communication cable or conduit 54. The controller 14 is also wired to the junction box 18 through an electrical, fiber optic, or other suitable communication cable or conduit 58 to receive information from the sensors 34, 38, 42, 46, 50 of one of the docking stations 31 to facilitate control of the robot 26.

[0020] The robot 26 includes an end effector 62 having depending fingers 66 for selectively lifting trays from a conveyor and depositing the trays on containers at the docking stations 31. In this manner, trays having mail for a particular geographic region or ZIP code are loaded on the same container to facilitate delivery of the mail. The end effector 62 includes an end effector sensor 70, the significance of which is described below.

[0021] FIG. 3 illustrates one of the docking stations 31. The cart docking station 31 has a plurality of fixtures for positioning containers at predetermined locations. In particular, the docking station 31 includes a weldment plate, ground plate, or support surface 74 mounted to the floor 78 of the building in which the system 10 is housed. First and second wheel-retaining cut-outs, wells, or recesses 82, 84 are formed in the ground plate 74. Wheel ramps 88 are formed in the ground plate 74 at its edge and within the wheel-retaining recesses 82, 84 to permit the wheels 92 of wheeled carts 96 (FIGS. 5-7) to roll onto the ground plate 74 and into the wheel-retaining recesses 82, 84. The wheel-retaining recesses 82, 84 resist unwanted removal of mail carts 96 from the docking station 31. The docking station 31 also includes pallet guide plates or members 100 and cart guide plates or members 104 welded or otherwise affixed to the ground plate 74. Referring to FIGS. 3 and 4, the cart guide plates 104 form a chute or V-shaped receiving portion 108 that receives a mail cart wheel 92, a channel portion 112 into which the V-shaped receiving portion 108 centers the cart wheel 92, and an end plate or stopper 116 to stop the cart 96 from advancing too far.

[0022] The pallet guide plates 100 flare away from each other to facilitate receiving a pallet 120 (FIGS. 5 and 6) therebetween. The pallet guide plates 100 are substantially L-shaped to provide an abutment wall for the pallets 120 so that the pallets do not advance too far into the docking station 31. At least one of the pallet guide plates 100 is adjustable by means of slots 124 that receive studs 128 affixed to the ground plate 74. The adjustable pallet guide plate 100 may be slid within the range provided by the slots 124. When the desired position is attained, nuts are tightened down on the studs 128 to hold the pallet guide plate 100 in place.

[0023] With reference to FIGS. 4, 7, and 8, the docketing station 31 also includes a conduit cover or guard 132 having an interior portion 133 along which the sensor conduits 54 run. Straps or harnesses 136, preferably including Velcro hook-and-loop fasteners, are mounted on the conduit guard 132 to bundle the conduits 54 together, and to keep them above the floor 78 and clear of the cart wheels 92, pallets 120, and any workers or vehicles in or near the docking stations 31.

[0024] As best shown in FIGS. 3 and 4, the pallet sensor 34 is mounted on the conduit guard 132. A first sensor bracket or post 140 supports the first cart presence sensor 38 and first cart type sensor 46. A second sensor bracket or post 144 supports the second cart presence sensor 42 and second cart type sensor 50. The first and second cart presence sensors 38, 42 are disposed below and at an angle γ with respect to the first and second cart type sensors 46, 50, respectively. The angle γ is preferably between about 20° and 40°, to properly position the cart type sensors 46, 50 as discussed below.

[0025] Referring now to FIGS. 5 and 6, a single pallet 120 may be received between the pallet guide members 100 of a docking station 31. Alternatively, a pair of carts 96 may be positioned in the docking station 31. The carts 96 ride high enough on their wheels 92 to straddle the pallet guide members 100. The pallets 120 also have clearance so that they straddle a pair of the cart guide members 104.

[0026] When a pallet 120 is in the docking station 31, the pallet sensor 34 is blocked by the pallet 120, and informs the controller 14 of the presence of the pallet 120. The controller 14 causes the robot 26 to load the pallet 120 with trays in response to the information provided by the pallet sensor 34. The pallet 120 does not block any of the cart sensors 38, 42, 46, 50. In this regard, the pallet sensor 34 may be considered both a container presence sensor and a container type sensor, because the pallet sensor 34 informs the controller 14 that a container is present in the docking station 31, and that the container is a pallet 120.

[0027] The cart guide members 104 are positioned in the docking station 31 such that when one wheel 92 of the cart 96 is within the channel 112, another wheel 92 of the cart 96 is within the wheel-retaining recess 82 or 84. The respective first and second cart presence sensors 38, 42 determine whether a cart 96 is positioned in front of it, and relay this information to the controller 14. The respective first and second cart type sensors 46, 50 determine what type of cart 96 is present in the docking station 31 based on a characteristic of the mail cart 96. For example, Eastern Regional Mail Carts (“ERMC”) are different from General Purpose Mail Carts (“GPMC”), in that ERMC's include a plate not present in GPMC's. The cart type sensors 46, 50 are positioned to identify the presence or absence of the plate and therefore tell the controller 14 the cart type. The controller 14 loads the carts 96 in different manners based on the information provided by the cart type sensors 46, 50. As a backup, the end effector sensor 70 confirms the presence of the cart 96 before depositing a tray therein.

[0028] As can be seen from the above, the present invention provides a cart docking station that positions and detects containers used in a robotic system. Many possible forms of the invention may be constructed based on the teachings set forth herein. Therefore, while the present invention has been described in reference to particular embodiments and examples, it should be understood that the invention is not confined to the particular construction and arrangement of the components illustrated and described, but embraces all forms encompassed by the following claims.