Patent Publication Number: US-10766717-B2

Title: Dishwashing conveyance system and method

Description:
RELATED APPLICATIONS 
     This application is related to U.S. application Ser. No. 16/201,809 filed Nov. 27, 2018, U.S. application Ser. No. 16/201,833 filed Nov. 27, 2018, U.S. application Ser. No. 16/201,746 filed Nov. 27, 2018, and U.S. application Ser. No. 16/201,765 filed Nov. 27, 2018, which are incorporated herein by reference for all purposes. 
     FIELD OF THE INVENTION 
     This invention relates to dishwashing appliances, and more particularly, to conveyance systems for dishwashing appliances. 
     BACKGROUND OF THE INVENTION 
     High-volume commercial dishwashing industries tend to implement conveyor dishwashers to actively move dishware along an assembly line cleaning system. This type of cleaning system may include various cleaning zones, such as a pre-wash zone, a main wash zone, and a final rinse zone. Each zone is arranged downstream of the previous zone, and dishware is transported in a single direction through the system to encounter each dishwashing zone in a desired order. 
     Conveyor dishwashers typically include a conveyor belt to accommodate dishware directly, or to move dishware retained in racks through a cleaning cycle. The conveyor belt moves the dishware through successive zones and is provided with a tank that holds liquid to be sprayed in its respective zone. Since dishware is conveyed in one direction through each zone, however, it is not uncommon for spatter from liquid and debris from one zone to contaminate the next zone. 
     The nature of a conveyor dishwasher also requires a large footprint as dishes are moved through the cleaning process in series. Dirty dishes enter a first cleaning zone (such as a pre-wash zone), advance through successive cleaning zones (such as a main wash zone), and then finally emerge as clean dishes from a final cleaning zone (such as a final rinse zone) located a significant distance from the first cleaning zone in traditional systems. In addition, access to the surface of a dish in a conveyor dishwasher may be impeded by non-optimal orientation and packing of dishes. Neighboring dishes may obscure access to certain areas of the dish, thereby preventing effective cleaning. 
     Accordingly, what are needed are systems and methods to prevent contamination from liquid and debris spatter between successive dishwashing zones and to reduce the footprint traditionally associated with conveyor dishwashers. Also what are needed are systems and methods to optimally position and securely retain dishware during cleaning, thereby increasing dishwashing efficiencies and throughput by ensuring effective access to the dish surfaces. Finally what is needed are systems and methods to allow dishwashing stages or zones to operate in parallel, such that dirty dishes enter the system and clean dishes exit the system substantially simultaneously. Such systems and methods are disclosed and claimed herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through use of the accompanying drawings, in which: 
         FIG. 1A  is a side view of one embodiment of a system for conveying dishware in accordance with the invention; 
         FIG. 1B  is a side view of one embodiment of a conveyance assembly in accordance with the invention; 
         FIG. 1C  is a side view of an alternative embodiment of a conveyance assembly in accordance with the invention; 
         FIG. 1D  is a side view of a third embodiment of a conveyance assembly in accordance with the invention; 
         FIG. 1E  is a side view of a fourth embodiment of a conveyance assembly in accordance with the invention; 
         FIG. 2  is a side view of the system of  FIG. 1A  loading dishware onto a conveyance assembly in accordance with embodiments of the present invention; 
         FIG. 3A  is a cutaway view of one embodiment of a robotic manipulator in accordance with the present invention; 
         FIG. 3B  is a cutaway view of the robotic manipulator of  FIG. 3A  with its end effector actuated in accordance with certain embodiments of the invention; 
         FIG. 4A  is a perspective view of a motor to actuate a conveyance assembly in accordance with certain embodiments of the invention; 
         FIG. 4B  is a perspective view of sensors implemented to facilitate the operation of the conveyance assembly in accordance with embodiments of the invention; 
         FIG. 4C  is a perspective view of one embodiment of a system for powering a conveyance assembly and/or grasping element in accordance with the invention; 
         FIG. 5  is a perspective view of a conveyance assembly in accordance with certain embodiments of the invention; 
         FIG. 6A  is cutaway view of a conveyance assembly in accordance with embodiments of the invention; 
         FIG. 6B  is a side view of one embodiment of a conveyance assembly with grooves to retain dishware in accordance with the invention; 
         FIG. 6C  is a side view of one embodiment of a conveyance assembly with articulating mechanisms that use gravity to actuate and retain dishware in accordance with the invention; 
         FIG. 6D  is a side view of a conveyance assembly having baskets to retain dishware in accordance with certain embodiments; 
         FIG. 6E  is a side view of a conveyance assembly interacting with an offboard contact point to shear dishware therefrom in accordance with certain embodiments; 
         FIG. 6F  is a perspective view of one embodiment of a conveyance assembly with an articulating grasping element to retain dishware in accordance with the invention; 
         FIG. 6G  is a perspective view of one embodiment of a conveyance assembly with articulating pincers to retain dishware in accordance with the invention; 
         FIG. 6H  is a perspective view of one embodiment of a conveyance assembly with articulating claws to retain dishware in accordance with the invention; 
         FIG. 6I  is a cross-sectional view of a conveyance assembly having a bell crank linkage to actuate a grasping element in accordance with certain embodiments; 
         FIG. 6J  is a cross-sectional view of the bell crank linkage of  FIG. 6I  actuated to a different position in accordance with certain embodiments of the invention; 
         FIG. 7A  is a perspective view of a receiving surface and conveyance assembly in accordance with embodiments of the invention; 
         FIG. 7B  is a perspective view of an anti-slip element in a bow-tie configuration in accordance with one embodiment of the invention; 
         FIG. 7C  is a perspective view of an anti-slip element in a C-shape configuration in accordance with another embodiment of the invention; 
         FIG. 7D  is a perspective view of an anti-slip element in a cross configuration in accordance with another embodiment of the invention; 
         FIG. 7E  is a side view of a grasping element sprung to bring dishware into contact with an anti-slip element in accordance with certain embodiments of the invention; 
         FIG. 7F  is a side view of the grasping element of  FIG. 7E  having the dishware engaged therewith; 
         FIG. 7G  is a perspective view of a transitional anti-slip element in accordance with embodiments of the invention; 
         FIG. 7H  is a perspective view of another embodiment of a transitional anti-slip element in accordance with embodiments of the invention; 
         FIG. 8A  is a cross-sectional view of an input mechanism element for the offboard actuator to engage the grasping element&#39;s onboard transmission mechanism in accordance with embodiments of the invention; 
         FIG. 8B  is a side view of one embodiment of a grasping element utilizing a biasing element to maintain a grasp on dishware in an unpowered state; 
         FIG. 8C  is a side view of the grasping element of  FIG. 8B  showing application of a transmission force; 
         FIG. 8D  is a side view of the grasping element of  FIG. 8B  showing its engagement with dishware; 
         FIG. 8E  is a side view of the grasping element of  FIG. 8B  showing its grasp on dishware in an unpowered state; 
         FIG. 9A  is a cross-sectional view of a conveyance assembly and multiple grasping elements in accordance with certain embodiments of the invention; 
         FIG. 9B  is a side view of a rotating magnetic grasping element, also referred to as a magnetic base mechanism, in accordance with one embodiment of the invention; 
         FIG. 9C  is a side view of another embodiment of a rotating magnetic grasping element in accordance with the invention; 
         FIG. 9D  is a side view of another embodiment of a rotating magnetic grasping element in accordance with the invention; 
         FIG. 9E  is a side view of another embodiment of a rotating magnetic grasping element in accordance with the invention; 
         FIG. 10  is a cross-sectional view of a dual pole magnetic grasping element in accordance with certain embodiments of the invention; 
         FIG. 11  is a cross-sectional view of a grasping element retracted from a receiving surface in accordance with one embodiment of the invention; 
         FIG. 12  is cross-sectional view of a grasping element extended from a receiving surface in accordance with another embodiment of the invention; 
         FIG. 13A  is a schematic diagram of a process that a single magnetic grasping element may undergo during the rotation of a conveyance assembly through stages of a cleaning cycle in accordance with embodiments of the invention; 
         FIG. 13B  is a side view of dishware being magnetically handed off from a grasping element to an end effector in accordance with the invention; 
         FIG. 13C  is a side view of the dishware of  FIG. 13B  showing magnetic engagement between the grasping element and end effector; 
         FIG. 13D  is a side view of the dishware of  FIG. 13B  showing the end effector receiving the dishware; and 
         FIG. 14  is a flow chart illustrating a process for conveying dishware through a cycle in accordance with certain embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , high-volume commercial dishwashing industries require high-throughput of dishes through multiple independent cleaning zones or stages. Such cleaning stages may include, for example, a pre-wash stage, a main wash stage, and a final rinse stage. Each stage may be arranged downstream of the previous zone, and dishware may be transported in a single direction through the system such that it encounters each dishwashing stage in a desired order. 
     Some features and characteristics of traditional conveyor dishwashers, however, may be inherently inefficient or otherwise disadvantageous to industry cleaning goals. For example, some dishwashing stages may spray liquid at high pressures and flow rates to remove debris from the dishware and to provide sanitization. Spatter and debris from one stage may thus inadvertently contaminate dishware in a next stage. Additionally, the single linear direction of travel for dishware to advance through multiple stages of a traditional conveyor dishwasher requires a machine having a large footprint. Finally, access to the surface of a dish in a conveyor dishwasher may be impeded by non-optimal orientation and packing of dishes. Embodiments of the present invention address these issues. 
     As used herein, the term “dishware” refers to any type of dish for preparing or serving food, including plates, bowls, platters, pots, pans, glasses, mugs, cups and/or any other type of tableware or cookware known to those in the art. 
     As shown in  FIG. 1A , one embodiment of a system  100  for conveying dishware through a cleaning cycle may include a conveyance assembly  102  and a robotic manipulator  104 . The robotic manipulator  104  may include an arm with one or more degrees of freedom to move dishware  106  from one location  120  to another. 
     The robotic manipulator  104  may include any configuration known to those in the art including, for example: serial, parallel, Delta, gantry, linear conveyor, rotary conveyor, or the like. Likewise, the robotic manipulator  104  may include one or multiple degrees of freedom, having any combination of active and passive joints. In one embodiment, the robotic manipulator  104  may include a first joint  114  connected to an actuator  124 , and a second joint  122  having an end effector  108  to grasp dishware  106  having various shapes and sizes. The actuator  124  may include any electrical, solenoid, magnetic, hydraulic, pneumatic or other type of actuator  124  known to those in the art. The end effector  108  may utilize any method known to those in the art to grasp the dishware  106  and transfer the dishware  106  to the conveyance assembly  102 . 
     In certain embodiments, for example, the end effector  108  may utilize magnets, mechanically interlocking geometries, traction locking, suction, vacuum, or the like, to engage and/or retain the dishware  106 . The conveyance assembly  102  may retain the dishware  106  via one or more grasping elements associated with a receiving surface thereof, as discussed in more detail below. 
     In certain embodiments, the conveyance assembly  102  may rotate about a single axis  112  to convey the dishware  106  through multiple independent stages of a cleaning cycle. This axis  112  may be horizontal, vertical, or any angle in between, and may convey the dishware  106  through independent cleaning stages. Such cleaning stages may include, for example, an acquisition stage to load dishware  106  onto the conveyance assembly  102 , a cleaning stage, a rinsing stage, a sanitizing stage, a drying stage, a sensing stage to determine whether the dishware  106  is adequately clean, and an unloading stage to unload the dishware  106  from the conveyance assembly  102 . In certain embodiments, at least two of the cleaning stages correspond to unique physical locations. 
     The conveyance assembly  102  may move its receiving surfaces  116  and attached dishware  106  to each physical location associated with a cleaning stage to convey the dishware  106  through the cleaning cycle. As previously mentioned, the conveyance assembly  102  may rotate about a single axis  112  for this purpose. In some embodiments, the conveyance assembly  102  may rotate about more than one axis  112 . Rotation about the axis  112  may be intermittent or continuous, and in some cases, may be reversible to facilitate reprocessing dishware  106  that is inadequately cleaned the first time through. In one embodiment, the conveyance assembly  102  may rotate about the axis  112  in a reciprocating or back-and-forth motion. 
     In some embodiments, the conveyance assembly  102  may be radially symmetric relative to the axis  112  of rotation. For example, as shown in  FIGS. 1B-E , the conveyance assembly  102  may form a prismatic volume  110  such as a two-sided platform, a triangle, a rectangle, a hexagon, or an n-sided polygon. In other embodiments, the conveyance assembly  102  may be non-radially symmetric about the axis  112  of rotation and may include, for example, a wedge shape, a half-circle, a panel with an offset center of rotation, or the like. 
     Receiving surfaces  116  of the conveyance assembly  102  may be substantially planar and include dimensions sufficient to accommodate various types and sizes of dishware  106 . Receiving surfaces  116  may be oriented such that their normal vectors point radially, parallel to, or orthogonal to a primary axis  112  of rotation. As discussed in more detail below, in some embodiments, the conveyance assembly  102  and/or receiving surfaces  116  may include features  126  to physically shield independent cleaning stages from cross-contamination. 
     Referring now to  FIG. 2 , a system  200  for conveying dishware  106  through various independent stages  208   a - d  of a cleaning cycle may include an actuator  124  adapted to move a robotic manipulator  104  between various positions. In certain embodiments, one or more articulated joints  114 ,  122  of a robotic manipulator  104  may rotate or otherwise move to position an associated end effector  108  as desired. 
     In one embodiment, the robotic manipulator  104  may position the end effector  108  to passively or actively engage dishware  106 . In some embodiments, the end effector  108  may be positioned to engage dirty dishware  106  stacked or otherwise placed in a location  120  proximate to other system  200  components. For example, dishware  106  may be located on a conveyor belt or stacked on a cart, elevator, or table adjacent to the system  200 . 
     In certain embodiments, the end effector  108  may passively engage the dishware  106  using, for example, one or more springs, levers, cam followers, magnets, suction cups, or the like. In other embodiments, engagement between the end effector  108  and the dishware  106  may be actively driven using electric motors, hydraulics, pneumatics, electromagnetic actuators, electrostatic actuators, or any other such device or method known to those in the art. 
     In one embodiment, the dishware  106  may include a ferromagnetic component attached thereto or integrated therein. For example, the dishware  106  may include one or more elements such as neodymium, iron, boron, samarium, cobalt aluminum, nickel, ceramic ferrite, stainless steel, or any other magnetic material known to those in the art. The end effector  108  may quickly and securely engage the ferromagnetic component of the dishware  106  using permanent and/or electromagnets. 
     Specifically, a magnetic field applied by the end effector  108  may attract the ferromagnetic component of the dishware  106 . The end effector  108  may then engage the ferromagnetic component of the dishware  106 . The robotic manipulator  104  may move the end effector  108  from a first location to a second location, thereby transferring the dishware  106  from its original location  120  to the conveyance assembly  102 , for example. 
     In other embodiments, as previously mentioned, the end effector  108  may implement a mechanical retaining mechanism to engage and retain the dishware  106 . The mechanical retaining mechanism may be substantially fixed and may utilize passive, unpowered components to cause the mechanism to engage the dishware  106 . A mechanical retaining mechanism may include, for example, a basket, a cage, hooks, a permanent magnet, a suction cup, or other such mechanism or device. The mechanical retaining mechanism may be activated by changing its orientation or otherwise altering the gravitational force on the mechanism to cause the mechanism to engage the dishware  106 . Alternatively, the mechanism may be activated by application of mechanical force, such as placing the mechanism against the dishware  106 , for example. 
     Of course, various types of end effectors  108  may be implemented to mechanically engage dishware  106 , and may include, for example, elements that are spring-loaded, gear-driven, magnetic, electrostatic, pneumatic, hydraulic, mechanically-interlocking, adherent, and/or any other such elements known to those in the art. 
     The conveyance assembly  102  may receive dishware  106  from an end effector  108  via one or more grasping elements. As discussed in more detail below, grasping elements may be attached to or otherwise associated with a receiving surface  116  of the conveyance assembly  102 , and may include magnetic attachment mechanisms, mechanical retaining mechanisms, powered or unpowered vacuum or suction mechanisms, or any other such retaining mechanisms known to those in the art. In some embodiments, powered and unpowered grasping elements may be implemented simultaneously in any number on a single receiving surface  116 . 
     In one embodiment, one or more sensors may be coupled to or otherwise associated with the location  120  to detect the dishware  106 . Sensors may include, for example, lidar sensors, radar sensors, camera sensors, weight sensors, or the like. In certain embodiments, data gathered from the sensors may be used to identify the dishware  106  by its type or size, for example. 
     Upon sensing the dishware  106 , the sensor may send a signal to a processor or server to substantially align the end effector  108  of the robotic manipulator  104  with the dishware  106 . In another embodiment, the end effector  108  may be aligned with the dishware  106  manually, automatically, or by any other means known to those in the art. The end effector  108  may then grasp the dishware  106  and move it to substantially correspond to a location of a grasping element of the conveyance assembly  102 . 
     Referring now to  FIGS. 3A and 3B , embodiments of the invention may implement end effectors  108  on one or more robotic manipulators  104  to load and unload dishware  106  from the conveyance assembly  102 . In one embodiment, an actuator  124  may be connected to an arm  302  of the robotic manipulator  104 . The actuator  124  may include any electrical, solenoid, magnetic, hydraulic, pneumatic or other type of actuator known to those in the art. A transmission mechanism including, for example, a linear drive, a slider crank, a push/pull cable, a rack and pinion, a spring, a belt, or the like, may be implemented to transfer power from the actuator  124  to move the end effector  108 . 
     As shown, an arm  302  may have two degrees of freedom provided by a first joint  114  and a second joint  122 . Of course, embodiments in accordance with the invention may include robotic manipulators  104  having one or multiple degrees of freedom, where any number of passive or active joints  114 ,  122  may be implemented in any combination. For example, embodiments of a robotic manipulator  104  may implement one active joint, one active and one passive joint, two active joints, or the like. 
     In some embodiments, the end effector  108  may include one or more permanent or electromagnets to grasp dishware  106  having a ferromagnetic component. In certain embodiments that contain permanent magnets, the end effector  108  may include a switchable magnetic base mechanism; a permanent magnet with a bell-like housing to increase magnetic flux density; dual opposing-pole permanent magnets, or the like. 
     In one embodiment, a second joint  122  may passively couple the magnetic end effector  108  to the arm  302 . As shown in  FIG. 3B , as the arm  302  approaches a conveyance assembly  102 , the end effector  108  may respond to magnetic forces between a ferromagnetic component of dishware  106  on the conveyance assembly  102  and the end effector  108 . The end effector  108  may swing towards or away from the dishware  106  or conveyance assembly  102  in response to such magnetic forces. 
     Referring now to  FIGS. 4A-C , certain embodiments of a conveyance assembly  102  in accordance with the present invention may utilize a motor  400  or other actuator to power rotation of the conveyance assembly  102  through various independent stages  208   a - d  of a cleaning cycle. Such actuation may utilize electric, solenoid, electromagnetic, hydraulic, pneumatic, or other such motors or devices known to those in the art. 
     In some embodiments, the motor  400  may transmit power to a shaft  402  to rotate the conveyance assembly  102  about a corresponding horizontal axis  112 . In such embodiments, the conveyance assembly  102  may be supported on one side via a cantilevered shaft  402 , or on two sides via shafts  402  on either side of the conveyance assembly  102 . Such shafts  402  may be fixed or integral to the conveyance assembly  102  or, in some embodiments, may be fixed to an offboard structure such that the conveyance assembly  102  affixes to the shaft  402  via a through-hole. 
     In some embodiments, rotation actuation of the conveyance assembly  102  may be accomplished offboard in a different manner. In one embodiment, the conveyance assembly  102  may be entirely supported by its outer edges, such that it rolls within a frame or structure that is actuated. In another embodiment, the conveyance assembly  102  may include a gear-toothed profile on an edge or face such that an offboard, powered drive gear meshes with the gear-toothed profile on the conveyance assembly  102  to rotate the conveyance assembly  102 . In the embodiment depicted by  FIG. 4C , as the conveyance assembly rotates, offboard mechanical features  410  may interact with features  412  articulating on the conveyance assembly  102 . As discussed in more detail below, this type of interaction between offboard and onboard features  410 ,  412  may also power grasping elements  600  located on the conveyance assembly  102 . 
     In other embodiments, rotation actuation of the conveyance assembly  102  may be onboard. For example, a rotary actuator may be located inside the conveyance assembly  102  and electrical power may be commutated or wirelessly transmitted to the conveyance assembly  102 . 
     In some embodiments, a plate  406  may separate the axis  112  from the motor  400 . As shown in  FIG. 4A , in certain embodiments, the plate  406  may be equipped with various sensors to sense dishware  106  in proximity to a receiving surface  116  of the conveyance assembly  102 . In other embodiments, sensors  408  may be included on a receiving surface  116  to sense the dishware  106 , or elsewhere onboard or offboard of the conveyance assembly  102 , as depicted by  FIG. 4B . 
     Sensors  408  may, for example, detect the presence or absence of dishware  106  on a receiving surface  116 , a location of the dishware  106 , a type of dishware  106 , a size of the dishware  106 , or the like. In some embodiments, such sensors  408  may be used to specifically identify such dishware  106 . Sensors  408  may include, for example, camera sensors, lidar sensors, radar sensors, weight sensors, or the like. This information may be used to determine appropriate cleaning parameters and/or to flag and reject certain dishware  106  from processing. 
     Sensors  408  onboard or internal to the conveyance assembly  102  may transmit signal data off of the conveyance assembly  102  by, for example, wired or wireless signal transfer or the like. Sensors  408  situated external to the conveyance assembly  102  may also transmit signal data via wired or wireless signal transfer. 
     Referring now to  FIG. 5 , in some embodiments, a system  500  in accordance with embodiments of the invention may include a conveyance assembly  102  having two or more receiving surfaces  116 , each receiving surface  116  having dimensions sufficient to accommodate various types and sizes of dishware  106 . One or more lobes  502   a ,  502   b  or other geometries or features may be coupled to or extending from an edge of a receiving surface  116 . In some embodiments, lobes  502   a ,  502   b  may extend at an angle from the receiving surface  116  to provide a gradual slope for dishware  106  to slide off. Such lobes  502   a ,  502   b  or other features may be implemented to facilitate reliable removal of dishware  106  or direct a flow of water and/or other liquid and debris, for example. 
     In one embodiment, the dimensions and features of a receiving surface  116  may substantially correspond to a surrounding structure of an independent stage  208   a - d . In certain embodiments, an independent cleaning stage  208   a - d  may direct liquid (including detergents, water, and other chemicals) towards the dishware  106 . In one embodiment, a receiving surface  116  and its associated lobes  502   a ,  502   b  may coordinate with features of the surrounding structure of the cleaning stage  208   a - d  to isolate the liquid and/or debris within the stage  208   a - d.    
     In other embodiments, powered or unpowered features of the conveyance assembly  102  may also isolate stages  208   a - d  to avoid cross-contamination between stages  208   a - d . For example, powered, articulating sealing surfaces may retract while the conveyance assembly  102  is rotating, and may extend when the conveyance assembly  102  is stationary. Alternatively, as discussed above, unpowered, static features on the conveyance assembly  102  (such as lobes  204   a ,  204   b ) and/or surrounding system  500  structure may intermittently form a closed, isolated volume at an independent stage  208   a - d . Such features may extend from the conveyance assembly  102 , the surrounding structure, or both, to shield independent stages  208   a - d  from each other. 
     As discussed in more detail below, a receiving surface  116  may include an anti-slip element  504  to mediate contact between dishware  106  and the receiving surface  116 . In one embodiment, the anti-slip element  504  may be a high friction pad or other material or coating on a substantially low friction receiving surface  116 . In certain embodiments, the anti-slip element  504  may maintain a high coefficient of friction when wet. The anti-slip element  504  may comprise, for example, an elastomer such as natural latex, neoprene rubber, nitrile rubber, polyurethane rubber, silicon rubber, ethylene propylene diene monomer rubber, or the like. 
     In certain embodiments, an axial locking mechanism may be removably affixed to or engaged with the axis  112  to lock the conveyance assembly  102  into place during operation. In some embodiments, the conveyance assembly  102  may be easily removed from the system  500  for cleaning or repair by disengaging the axial locking mechanism such that the conveyance assembly  102  is not axially restrained. The conveyance assembly  102  may be fully sealed to protect internal components from damage from liquid and debris, and to facilitate cleaning. Additionally, in some embodiments, articulating elements on the conveyance assembly  102  may also be sealed. In one embodiment, the conveyance assembly  102  may be fully sealed to the system  500  chassis and not removable. 
     In some embodiments, the conveyance assembly  102  may include a side wall  118  coupled to one or more sides of the conveyance assembly  102 . A portion of the side wall  118  may include a rubber, plastic, elastomeric, or other cushioning element  126  or pad coupled thereto to protect the conveyance assembly  102  in case it is inadvertently dropped or inadequately secured during operation. In certain embodiments, the cushioning element  126  may be coupled to an outer edge of the side wall  118 . 
     In one embodiment, the side wall  118  includes a rubber grip circumferentially molded around its outer edge. Additionally, in some embodiments, one or more handholds  506  may be integrated into or attached to the side wall  118  to facilitate handling. In some embodiments, such handholds  506  may also function as throughways so as not to obstruct any offboard sensors  408 . 
     Referring now to  FIGS. 6A-J , in some embodiments, the conveyance assembly  102  may house one or more grasping elements  600   a ,  600   b ,  600   c  corresponding to a receiving surface  116  of the conveyance assembly  102 . Any combination of powered or unpowered grasping elements  600   a ,  600   b ,  600   c  may be implemented to receive and retain dishware  106  during a cleaning cycle. Grasping elements  600   a ,  600   b ,  600   c  may also remove or allow for the removal of dishware  106  from receiving surfaces  116 . 
     As shown in  FIGS. 6B-E , static grasping elements  600   a ,  600   b ,  600   c  may include, for example, fixed baskets or cages  614 , fixed hooks  606 , a fixed suction cup  616 , grooves  604 , or other such fixed mechanisms to grasp and retain dishware  106 . In some embodiments, unpowered grasping elements  600   a ,  600   b ,  600   c  may be activated by changing the orientation of the conveyance assembly  102  and gravity force vector to cause the grasping elements  600   a ,  600   b ,  600   c  to engage the dishware  106 . In other embodiments, unpowered grasping elements  600   a ,  600   b ,  600   c  may be activated by an external mechanical force, such as when dishware  106  is placed thereon. In still other embodiments, the grasping elements  600   a ,  600   b ,  600   c  may be activated by rotation of the conveyance assembly  102  which may force the grasping elements  600   a ,  600   b ,  600   c , or transmission elements connected to the grasping elements  600   a ,  600   b ,  600   c , against other points of contact offboard the conveyance assembly  102 , as previously discussed with reference to  FIG. 4C . In any case, unpowered grasping elements  600   a ,  600   b ,  600   c  may utilize or incorporate passive, unpowered mechanical components to grasp dishware  106 , such as springs, levers, cams, and the like. 
     As shown in  FIGS. 6F-J , other embodiments of the invention may utilize powered grasping elements  600   a ,  600   b ,  600   c  that articulate to geometrically engage and retain dishware  106 . In some embodiments, a powered grasping element  600   a ,  600   b ,  600   c  may include a mechanical grasping mechanism that articulates to apply force and traction to the surface of dishware  106 . In alternative embodiments, a powered grasping element  600   a ,  600   b ,  600   c  may include a mechanism based on powered vacuum suction, such as the Venturi effect. In one embodiment, powered grasping elements  600   a ,  600   b ,  600   c  may include an electromagnet and/or permanent magnets which may move to grasp or release dishware  106  having a ferromagnetic component. 
     Powered articulating grasping elements  600   a ,  600   b ,  600   c  may include, for example, fingers, arms  618 , claws  620 , pincers  622 , a prismatic gripper, or the like, and may be powered by any electromagnetic, hydraulic, pneumatic, or other type of motor or actuator known to those in the art. In some embodiments, an actuation source may be internal to the conveyance assembly  102 , such that electrical power may be commutated into the conveyance assembly  102 , or transferred wirelessly. 
     Both passive and active grasping elements  600   a ,  600   b ,  600   c  may remove or allow for the removal of dishware  106  from receiving surfaces  116 . In some embodiments, the orientation of a receiving surface  116  and gravity may work to remove dishware  106  from a grasping element  600   a ,  600   b ,  600   c  attached to the receiving surface  116 . As shown in  FIG. 6D , for example, a grasping element  600   a ,  600   b ,  600   c  may respond to a changing gravity direction vector by, for example, causing a basket-type grasping element  600   a ,  600   b ,  600   c  to open to allow the dishware  106  to fall. In other embodiments, articulating grasping elements may be driven by the changing direction of gravity acting on dishware  106  to lever the mechanism. 
     In some embodiments, articulating passive grasping elements  600   a ,  600   b ,  600   c  may interact with offboard geometries to disengage from dishware. For example, as shown in  FIG. 6E , dishware  106  may be removed by conveyance assembly  102  motion and a fixed hardstop  612 . In this case, the dishware  106  may run into hardstop  612  geometry that shears or pushes dishware  106  off of a receiving surface  116 . In other embodiments, dishware  106  may be removed by an articulating mechanism interacting with a grasping elements  600   a ,  600   b ,  600   c  onboard the conveyance assembly  102 . In still other embodiments, powered grasping elements  600   a ,  600   b ,  600   c  may reverse their grasp to actively release dishware  106 . 
     In some embodiments, as shown in  FIGS. 6I and 6J , for example, the actuator or actuation source may be external to the conveyance assembly  102 . In some embodiments, as discussed above with reference to  FIG. 4C , the actuator may interact with a point or feature on the conveyance assembly  102  distal to the grasping element  600   a ,  600   b ,  600   c  itself. The actuator may work through a transmission mechanism internal to the conveyance assembly  102  to direct mechanical power to the grasping element  600   a ,  600   b ,  600   c . Alternatively, an interaction point between the actuator and the transmission mechanism may be on the side of the conveyance assembly  102  with a rod and cap, for example, such that pushing or pulling on the cap actuates the grasping element  600   a ,  600   b ,  600   c.    
     A transmission mechanism may include, for example, a rack and pinion, a push/pull cable, a bell crank mechanism, a dual slider crank mechanism, a lever, a cam follower, or any other such mechanism known to those in the art. In one embodiment, as shown in  FIGS. 6I and 6J , the transmission mechanism may be an onboard bell crank linkage  608  driven by an offboard actuator pressing on an input piston  610 . Of course, a selected mode of transmission or transmission element may depend on the desired interaction method and grasping element  600   a ,  600   b ,  600   c  articulation. 
     Referring now to  FIGS. 7A-F , magnetic grasping may be much stronger in the normal direction than in the lateral direction relative to a face of a grasping element  600   a ,  600   b ,  600   c . To prevent premature shearing off and to stabilize attached dishware  106 , an anti-slip element  504  may be implemented beneath the dishware  106  on the receiving surface  116  of the conveyance assembly  102 . 
     In certain embodiments, an anti-slip element  504  may be coupled to or overlaid onto at least a portion of a receiving surface  116 . In addition to facilitating effective release of the dishware  106  following completion of the cleaning cycle, the anti-slip element  504  may also facilitate re-positioning dishware  106  attached to a grasping element  600   a ,  600   b ,  600   c , as discussed in more detail below. 
     In certain embodiments, an anti-slip element  504  may be patterned in a variety of ways, including voids, islands, and various shapes spaced apart from one another on the receiving surface  116 . For example, the anti-slip element  504  may have a bow-tie configuration (as shown in  FIG. 7B ), a c-shape configuration (as shown in  FIG. 7C ), a cross configuration (as shown in  FIG. 7D ), or the like. The anti-slip element  504  may stabilize dishware  106  relative to the receiving surface  116  when the dishware  106  is engaged by a grasping element  600 . 
     The anti-slip element  504  may be patterned, however, such that when dishware  106  is released from the grasping element  600 , the dishware  106  can be passively pulled off of the grasping element  600  with the force of gravity on the dishware  106 . Spaces between the anti-slip elements  504  may allow the dishware  106  to gently rock to the lower friction receiving surface  116  to avoid the anti-slip element  504  geometry as it is sheared off. A C-shape anti-slip element  504  configuration may restrict passive shear-off behavior in one direction, for example, while a bow-tie configuration may enable the dishware  106  to shear off from two opposite directions. 
     In embodiments having a magnetic grasping element  600  that translates the magnet in and out of the receiving surface  116 , the magnetic grasping element  600  may control contact between the dishware  106  and the anti-slip elements  504   a ,  504   b . For example, as discussed in more detail below, the grasping element  600  may selectively lift the dishware  106  off of the anti-slip elements  504   a ,  504   b . If the dishware  106  is not contacting any anti-slip elements  504   a ,  504   b  when it is lifted from the receiving surface  116  and it remains engaged with the magnetic grasping element  600 , the dishware  106  may be repositioned laterally as needed. When the magnetic grasping element  600  retracts into the receiving surface  116 , it may hold the dishware  106  against the anti-slip elements  504   a ,  504   b  to stabilize it. 
     In other embodiments, as shown in  FIGS. 7E-H , an anti-slip element  504   a ,  504   b  may be a mechanical assembly with a transitional friction property. For example, the anti-slip element  504   a ,  504   b  may include an array of elements, where each element has a slippery surface on one side and an anti-slippery surface on a reverse or opposing side. Each of the elements in the array may flip over to expose one side or the other. Actuating the array to flip over may be passive, such as with dishware  106  movement, or active via an actuator. In one embodiment, the elements may be radially arranged such that they flip over in response to a torque on dishware  106  in contact therewith. 
     In another embodiment, as shown in  FIGS. 7E and 7F , an anti-slip element  504   a ,  504   b  may be a spring-loaded mechanism that is normally slippery, but may become anti-slip when pressure is applied on dishware  106  in contact therewith. Pressure applied to the dishware  106  in this manner may press the spring-loaded mechanism down to engage the dishware  106  with a high-friction material. In other embodiments, an anti-slip element  504   a ,  504   b  may be a geometric feature that interlocks with coordinated geometries on the dishware  106 . 
     In certain embodiments, an actuation source external to the conveyance assembly  102  may interact with input interfaces  702   a ,  702   b ,  702   c , shown as rod and cap mechanisms in  FIG. 7A , to the transmission elements that engage other elements internal to the conveyance assembly  102  to actuate grasping elements  600 . Each input to the transmission elements  702   a ,  702   b ,  702   c  may independently control an individual grasping element  600   a ,  600   b ,  600   c.    
     As previously discussed, in certain embodiments, the input mechanisms  702   a ,  702   b ,  702   c  drive transmission elements that may include, for example, bell crank linkages or push/pull cables  812  to mediate between actuation source and grasping element and selectively translate grasping elements  600   a ,  600   b ,  600   c  between various positions relative to the receiving surface  116 . Shown in  FIG. 8A  is an input rod and cap mechanism  702   a ,  702   b ,  702   c  on the side wall of the conveyance wheel that an offboard linear actuation source may interact with to drive an onboard bell crank linkage or push/pull cable  812  transmission element, which may attach to a grasping element  600   a ,  600   b ,  600   c . This system is discussed in more detail below with reference to  FIGS. 11 and 12 . 
     As shown in  FIG. 8A , in some embodiments, a cap  804  may connect to the end of the spring-loaded rod  802 , to be nominally pushed in to actuate the transmission element. In certain embodiments, the rod cap  804  may be ferromagnetic such that the it can be pulled out by a magnetic interface attached to the offboard actuation source actuating the transmission element. In some embodiments, a server or processor may automatically control an actuator or motor connected to the transmission element  702 . 
     Additionally, in certain embodiments such as those depicted in  FIGS. 8B-E , transmission elements  702   a ,  702   b ,  702   c  may include a tension mechanism  806  (such as a spring and mandrel) to automatically apply tension to associated grasping elements  600   a ,  600   b ,  600   c  in an unpowered state. The natural propensity of a grasping element  600   a ,  600   b ,  600   c  to spring back with respect to a receiving surface  116  in this manner may effectively retain dishware  106  securely against the receiving surface  116  in an unpowered state. 
     Referring now to  FIG. 9A , in some embodiments, individual grasping elements  600   a ,  600   b ,  600   c  may correspond to unique receiving surfaces  116   a ,  116   b ,  116   c  of a conveyance assembly  102 . In other embodiments, more than one grasping element  600   a ,  600   b ,  600   c  may correspond to a single receiving surface  116   a . As shown, in certain embodiments, each grasping element  600   a ,  600   b ,  600   c  may be substantially centrally located relative to its respective receiving surface  116   a ,  116   b ,  116   c.    
     As previously discussed, in some embodiments, dishware  106  may be picked up by a robotic manipulator  104  and placed onto a grasping element  600   a ,  600   b ,  600   c  of a conveyance assembly  102 . Magnetic grasping elements  600   a ,  600   b ,  600   c  may be used to grasp dishware  106  having a ferromagnetic component. In any case, embodiments of the invention provide grasping elements  600   a ,  600   b ,  600   c  that may be engaged and disengaged repeatably and reliably to maximize dishwashing efficiencies. 
     Magnetic grasping mechanisms may be implemented in connection with a robotic manipulator  104  end effector  108 , grasping elements  600   a ,  600   b ,  600   c  coupled to a conveyance assembly  102 , or both. For simplicity, magnetic grasping mechanisms will be described in connection with grasping elements  600   a ,  600   b ,  600   c , but may be understood as having application to an end effector  108  as well. In either case, fixed, static electromagnets and/or permanent magnets may be used for grasping purposes. 
     Magnetic attraction force relative to dishware  106  ferromagnetic components may be controlled by transitioning magnetic grasping elements  600   a ,  600   b ,  600   c  between various states. Where electromagnets are used, they may be switched on to engage dishware  106  having a ferromagnetic component, and switched off to disengage such dishware  106 . 
     Where permanent magnets are used, they may be fixed such that they passively engage dishware  106  placed on their surface. Disengagement may be achieved by application of an external forcing element, such as a rigid stop that pries or shears off the dishware  106  as the grasping element  600   a ,  600   b ,  600   c  moves past it. In alternative embodiments, a controlled mechanism may actively pry or shear dishware  106  from the magnet. For example, in one embodiment, an actuated swiper arm mechanism onboard or offboard the conveyance assembly  102  may shear the dishware  106  from the grasping element  600   a ,  600   b ,  600   c . In another embodiment, a pry-off mechanism may be attached to the conveyance assembly  102  or end effector  108  to remove the dishware  106 . 
     In certain embodiments, a grasping element  600   a ,  600   b ,  600   c  may include permanent magnets that are switchable via an actuated switchable magnet mechanism, or magnetic base, known to those in the art. In such embodiments, as shown in  FIGS. 9B and 9C , magnetic flux output may be modulated by, for example, rotating a permanent magnet relative to its housing. The rotation of the magnets can also be performed as shown in  FIGS. 9D and 9E , by rotating the permanent magnets towards or away from the receiving surface plane. 
     In some embodiments of a grasping element  600   a ,  600   b ,  600   c , permanent magnets and electromagnets may be used simultaneously, such that when the electromagnets are energized they may create a magnetic field that is reverse to the magnetic field direction of the permanent magnets. This may result in a net reduction in output magnetic field strength from the magnetic grasping element  600   a ,  600   b ,  600   c  in which they are used. 
     Each grasping element  600   a ,  600   b ,  600   c  may include a transmission element  702   a ,  702   b ,  702   c  to selectively transition the grasping element  600   a ,  600   b ,  600   c  between at least two states. In some embodiments, one state may allow the grasping element  600   a ,  600   b ,  600   c  to engage dishware  106  while another state may allow the grasping element  600   a ,  600   b ,  600   c  to disengage the dishware  106 . In some embodiments, a transmission element  702   a ,  702   b ,  702   c  may also selectively lock a corresponding grasping element  600   a ,  600   b ,  600   c  into a desired position or state. 
     In one embodiment, a grasping element  600   a ,  600   b ,  600   c  may transition between an extended position and a retracted position relative to the receiving surface  116  of a conveyance assembly  102 . As discussed in more detail below, in some embodiments, an extended or neutral position may allow the grasping element  600   a ,  600   b ,  600   c  to grasp and retain dishware  106  while a retracted position may allow the grasping element  600   a ,  600   b ,  600   c  to disengage the dishware  106 . 
     In another embodiment, a grasping element  600   a ,  600   b ,  600   c  may rotate about an axis to transition between two or more states. The axis may be horizontal relative to the receiving surface  116 , and one or more magnets may be coupled to one side of the grasping element  600   a ,  600   b ,  600   c . As shown in  FIGS. 9D and 9E , in this manner, the grasping element  600   a ,  600   b ,  600   c  may grasp and retain dishware  106  when the magnets are positioned upward or substantially adjacent to the dishware  106 , and may disengage the dishware  106  when the grasping element  600   a ,  600   b ,  600   c  is rotated downward such that the magnets are away from the dishware  106 . 
     Various types and combinations of grasping elements  600   a ,  600   b ,  600   c  and transmission elements  702   a ,  702   b ,  702   c  may be used in a conveyance assembly  102 . For example, in one embodiment, a push/pull cable transmission element  702   a  may correspond to one grasping element  600   a , while a bell-crank linkage type transmission element  702   b  may correspond to another grasping element  600   b . Additionally, grasping elements  600   a ,  600   b ,  600   c  may be independently actuated such that one grasping element  600   a  may be extended relative to a corresponding receiving surface  116   a  while another grasping element  600   b  is retracted or neutral relative to its receiving surface  116   b . In this manner, each grasping element  600   a ,  600   b ,  600   c  and transmission element  702   a ,  702   b ,  702   c  is fully independent and able to function as needed with respect to any particular independent stage  208   a - d . Grasping elements can also be dependent and controlled simultaneously. 
     Referring now to  FIG. 10 , in some embodiments, a grasping element  600  may include one or more magnets  902  configured to quickly and securely grasp a ferromagnetic component integrated into or coupled to dishware  106 . For example, a grasping element  600  may comprise permanent and/or electromagnets  902  affixed to a movable housing  912  configured to move relative to the receiving surface  116 . In certain embodiments, as shown, the grasping element  600  may include two permanent magnets  902   a ,  902   b  positioned with opposing poles facing outward from the receiving surface  116 . The magnetic field created by this arrangement of magnets  902  may migrate ferromagnetic components of the dishware  106  to center relative to the two permanent magnets  902   a ,  902   b.    
     In certain embodiments, the housing  912  may translate or rotate relative to the receiving surface  116 , such that the magnets  902  may move towards the dishware  106  to engage the dishware  106 , and away from the dishware  106  to disengage the dishware  106 . In one embodiment, for example, the grasping element  600  may include magnets  902  on a rotating cylinder having a rotation axis parallel to the receiving surface  116 , as shown in  FIG. 9E . Alternatively, the rotating cylinder may have a rotation axis perpendicular to the receiving surface  116 . 
     In certain embodiments, a grasping element  600  may include magnets  902  configured to move laterally on the receiving surface  116 , shearing sideways. In other embodiments, magnets  902  may move normal to the receiving surface  116 , in and out. For example, as shown, the housing  912  may move the magnets  902  out of the receiving surface  116  to engage the dishware  106  and retract into the receiving surface  116  to disengage the dishware  106  by moving away from its ferromagnetic component. This embodiment may be particularly advantageous since many types of dishware  106  have a recessed surface on their underside, with a variable depth. Extending the grasping element  600  out from the receiving surface  116  in this manner may achieve consistent engagement with dishware  106 , despite variations in dishware recess depth. 
     In certain embodiments, the housing  912  may include a guide rod  908  and a linear bearing  910  to facilitate vertically transitioning the grasping element  600  between various positions relative to the receiving surface  116 . In some embodiments, the guide rod  908  may be integrated into a central portion of the housing  912  to stabilize and support the grasping element  600  as it moves between vertical positions, and to further provide support to dishware  106  engaged with the grasping element  600 . The linear bearing  910  may provide fluid movement of the grasping element  600  in transit between the various vertical positions. 
     In one embodiment, each of two permanent magnets  902   a ,  902   b  may include a backing plate  906   a ,  906   b  to focus a magnetic field. Upon engagement of the dishware  106  with the grasping element  600 , the backing plates  906   a ,  906   b  may concentrate the magnetic field through the dishware  106  to attract and center the dishware  106  relative to the magnets  902   a ,  902   b.    
     In some embodiments, a button cap  914  may be coupled to a top surface of the permanent magnets  902   a ,  902   b  to provide a smooth or slippery interface between the permanent magnets  902   a ,  902   b  and the dishware  106 . This slippery interface may facilitate re-positioning and/or centering the dishware  106  with respect to the magnets  902   a ,  902   b  and/or receiving surface  116 . Indeed, in certain embodiments, the slippery surface of the button cap  914  may allow the dishware  106  to slide laterally prior to being secured in place relative to the receiving surface  116 . Other forces acting on the dishware  106 , such as lateral streams of liquid at high pressure and/or application of a scrubber to the interior of the dishware  106 , may also facilitate centering the dishware  106 . 
     Movement of the grasping element  600  may be actuated using any actuation technology known to those in the art. For example, actuation may be accomplished via motors, hydraulics, pneumatics, electromagnetic actuators, electrostatic actuators, or the like. In some embodiments, extension or retraction of the housing  912  may be passive by implementing a spring or other biasing mechanism to bias the grasping element  600  toward a fully extended or retracted state. 
     Referring now to  FIGS. 11 and 12 , in certain embodiments, actuation may be binary such that the grasping element  600  is controlled between fully extended and fully retracted states. In other embodiments, actuation may control movement of the grasping element  600  between multiple discrete states, such as fully retracted, partially retracted, partially extended, and fully extended. In still other embodiments, actuation may control movement of the grasping element  600  through a continuous range of states between fully retracted and fully extended states. 
     The push/pull cable  812  and anti-rotation rod  1000  may slide within a tube  1002  to facilitate movement of the push/pull cable  812  between various positions. In certain embodiments, the length of the tube  1002  may determine a maximum distance that the grasping element  600  may be retracted or extended relative to the receiving surface  116 . 
       FIG. 13A  illustrates exemplary steps in a process  1300  for grasping and retaining dishware  106  through a cleaning cycle in accordance with embodiments of the invention. For example, some embodiments of the invention may include an acquisition stage  1302  to load dishware  106  onto a conveyance assembly  102 . A cleaning stage  1304  may then clean, and optionally dry, the dishware  106 , after which the dishware  106  may be unloaded from the conveyance assembly  102  in an unloading stage  1306 . 
     In certain embodiments, the acquisition stage  1302  may include four steps  1308 ,  1310 ,  1312 ,  1314 . In the first step  1308 , the grasping element  600  may be retained in a substantially neutral position relative to the receiving surface  116 . In one embodiment, the grasping element  600  may be unpowered such that a spring or other biasing mechanism passively retains the grasping element  600  in this position relative to the receiving surface  116  by default. Alternatively, the grasping element  600  may be powered to assume this position. 
     In a second step  1310 , the grasping element  600  may be actuated to vertically extend from the receiving surface  116 . The magnetic field created by the grasping element  600  may thus attract ferromagnetic components of the dishware  106 . In a third step  1312 , the grasping element  600  may grasp and retain a ferromagnetic component of the dishware  106 . In certain embodiments, the combination of the magnetic field generated by the grasping element  600  and its slippery surface may facilitate centering the dishware  106  relative to the grasping element  600 . 
     In the fourth step  1314 , the grasping element  600  may be retracted to pull the dishware  106  substantially against the receiving surface  116 . In other embodiments, power may be removed from the grasping element  600  such that the grasping element  600  returns to a default position via a spring or other biasing mechanism, thereby pulling the attached dishware  106  substantially against the receiving surface  116 . In some embodiments, the receiving surface  116  may include one or more anti-slip elements  504  to mediate contact between the dishware  106  and the receiving surface  116 . 
     As shown, a cleaning stage  1304  may include two steps  1316 ,  1318 . The first step  1316  may selectively translate the grasping element  600  to release the dishware  106  from the anti-slip element  504  and/or receiving surface  116  such that magnetic forces from the grasping element  600  and mechanical forces on the dishware  106  may re-position the dishware  106 . For example, as previously discussed, some embodiments of the grasping element  600  may include two permanent magnets. The magnetic field generated by the magnets may migrate ferromagnetic components of the dishware  106  to center relative to the two magnets. 
     In other embodiments, streams of water or other fluid may be sprayed toward the dishware  106  at high pressures or flow rates, and/or a scrubber or other mechanical device may make contact with an interior of the dishware  106 . Releasing the dishware  106  from the anti-slip element  504  and/or receiving surface  116  while maintaining attachment between the dishware  106  and the grasping element  600  in this manner may enable the dishware  106  to move laterally in response to such forces. In a second step  1318  of the cleaning stage  1316 , the grasping element  600  may be actively or passively retracted such that the dishware  106  is securely re-positioned relative to the anti-slip element  504  and/or receiving surface  116 . 
     An unloading stage  1306  may include selectively disengaging the dishware  106  from the grasping element  600 . A first step  1320  of the unloading stage  1306  may include actuating the grasping element  600  to retract from the receiving surface  116  and thereby reduce the magnetic field between the grasping element  600  and the ferromagnetic components of the dishware  106 . In this manner, the dishware  106  may be disengaged from the grasping element  600 . Of course, in other embodiments, disengaging the dishware  106  may include changing a state of the grasping element  600  by rotating the grasping element  600 , reversing a polarity thereof, or the like. In a second step  1322  of the unloading stage  1306 , the dishware  106  may be removed from the receiving surface  116  by using gravity to shear off the dishware  106 , mechanically prying the dishware  106  from the receiving surface  116 , or by any other technique known to those in the art. 
     In certain embodiments, as shown in  FIGS. 13B-13D , removing the dishware  106  from the receiving surface  116  may include magnetically handing off the dishware  106  from the grasping element  600  to a magnetic end effector  108  of a robotic manipulator  104 . Like the initial transfer of the dishware  106  onto the conveyance assembly  102  during the acquisition stage  1302 , the dishware  106  must be disengaged from one magnetic element to enable it to be grasped by another magnetic element. In some embodiments, magnetic handoff may be facilitated by controlling a differential in magnetic attraction force to the dishware  106  between the end effector  108  and the grasping element  600 . The dishware  106  may then attach to either the end effector  108  or the grasping element  600  depending on which exhibits higher magnetic attraction on the dishware  106 . 
     This differential in magnetic force may be achieved in numerous ways. In embodiments utilizing electromagnets, the strength of the electromagnet may be modulated by modulating their electric current. Where permanent magnets are used, their output strength may be modulated by controlling the distance and/or orientation between the dishware  106  and the magnet. 
     If magnetic force is consistently stronger on either the end effector  108  or the grasping element  600  than the other, handoff will always occur from the weaker to the stronger of the two. In certain embodiments, at least one of the end effector  108  and the grasping element  600  may be modulated in output magnetic strength by translating or rotating a permanent magnet thereof relative to the dishware  106 , or by controlling current through an electromagnet to either weaken its own output or to counteract the fields of an adjacent permanent magnet. 
     In one embodiment, for example, dishware  106  may be magnetically grasped by an end effector  108  of a robotic manipulator  104  and moved to a magnetic grasping element  600  of a conveyance assembly  102 . The end effector  108  attached to the dishware  106  may approach and, in some embodiments, make contact with the grasping element  600 . The magnetic attraction of the dishware  106  to the grasping element  600  may be made stronger than the magnetic attraction of the dishware  106  to the end effector  108  by, for example, reducing the magnetic attraction of the end effector  108  or increasing the magnetic attraction of the grasping element  600 . In other embodiments, the magnetic attraction of the grasping element  600  may be constantly stronger than the magnetic attraction of the end effector  108  such that no controlled changes to magnetic attraction are needed. The dishware  106  may then be transferred from the end effector  108  to the grasping element  600 . The robotic manipulator  104  may then move away from the dishware  106  on the grasping element  600 . 
     This magnetic handoff process may be reversed to remove the dishware  106  from a grasping element  600  of the conveyance assembly  102 . For example, as shown in  FIG. 13B , dishware  106  may be grasped by the grasping element  600  on the conveyance assembly  102 . A robotic manipulator  104  with a magnetic end effector  108  may approach and/or make contact with dishware  106  on the grasping element  600 , as shown in  FIG. 13C . The magnetic attraction of the dishware  106  to the end effector  108  may be made stronger than the magnetic attraction of the dishware  106  to the grasping element  600  to enable the end effector  108  to remove the dishware  106  therefrom, as shown in  FIG. 13D . 
     As above, this may be accomplished in various ways. In one embodiment, the end effector  108  magnetic attraction may be increased. In another embodiment, the grasping element  600  magnetic attraction may be reduced. In still another embodiment, no controlled changes may be made to magnetic attraction. Rather, magnetic attraction of the grasping element  600  may be constantly weaker than the magnetic attraction of the end effector  108 . 
     As shown in  FIG. 13D , the dishware  106  may then be transferred from the grasping element  600  to the end effector  108 . The robotic manipulator&#39;s  104  end effector  108  may then be moved away from the grasping element  600  with the dishware  106  attached. 
     Referring now to  FIG. 14 , a method  1400  for conveying dishware  106  through a cleaning cycle in accordance with embodiments of the invention may include grasping  1402  dishware from a location, such as conveyance belt or stack. In some embodiments, a robotic manipulator may utilize an end effector to grasp the dishware, as discussed above. 
     The dishware may then be transferred  1404  to a receiving surface. The receiving surface may be included on a conveyance assembly or wheel, and may include a grasping element. The grasping element may be actuated  1406  to grasp and retrieve the dishware from the end effector of the robotic manipulator. In certain embodiments, both the end effector of the robotic manipulator and the grasping element of the conveyance assembly may be magnetic. Accordingly, in some embodiments, either the end effector or the grasping element may reduce or increase its magnetic field to effectuate hand off of the dishware to the other. In certain embodiments, no controlled changes may be made to magnetic attraction of the grasping element or end effector. Rather, magnetic attraction of one may be constantly weaker or stronger than the magnetic attraction of the other. 
     After handoff to the grasping element, the method  1400  may query whether the dishware is securely retained  1408  and centered  1412  relative to the grasping element. In certain embodiments, sensors may be used to make this determination. If not, the dishware may be repositioned  1410  by, for example, changing a state of the grasping element to temporarily disengage the dishware from the receiving surface and allow magnetic and/or mechanical forces to move the dishware laterally with respect to the grasping element. The method  1400  may then return to query whether the dishware is securely retained and centered relative to the grasping element. If yes to both  1408 ,  1412 , the dishware  106  may be conveyed  1414  through each stage of a cleaning cycle. 
     Upon completion of the cleaning cycle, or at any other desired point in the process, the method  1400  may disengage  1416  the dishware from the grasping element by actively or passively changing a state of the grasping element, as discussed in detail above. In some embodiments, gravity acting on the dishware may shear the dishware from the receiving surface. In other embodiments, a mechanical feature onboard or offboard the conveyance assembly may pry the dishware from the grasping element and receiving surface. In certain embodiments, an end effector of a robotic manipulator may then grasp the dishware and move it to a new location. 
     In the above disclosure, reference has been made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific implementations in which the disclosure may be practiced. It is understood that other implementations may be utilized and structural changes may be made without departing from the scope of the present disclosure. References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. 
     While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the disclosure. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. The foregoing description has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. Further, it should be noted that any or all of the aforementioned alternate implementations may be used in any combination desired to form additional hybrid implementations of the disclosure.