Abstract:
A system and method for managing food production, inventory and delivery in a restaurant by automatically monitoring the types and quantities of food types that have been cooked and are in a cooked food holding area. Food holding trays are equipped with radio frequency identification (RFID) tags, and holding cabinets are equipped with RFID interrogators. The type and quantity of food items are determined manually or by machine vision or weighing systems, and the data is stored on the RFID tags and in a controller. The system manages the use of food items on a first-in, first-out basis, alerts operators when the inventory of an item is nearing exhaustion, and alerts operators when food items in the holding area must be discarded. The system manages movable trays of food no matter where in the facility they are located.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to a system and method for managing food production, inventory and delivery in a restaurant, and in particular to a system and method using radio frequency identification (RFID) technology for managing production, inventory and delivery of a variety of food items in a quick service restaurant.  
       BACKGROUND OF THE INVENTION  
       [0002]     In restaurants and other food service establishments there is a need to process food uniformly, to maintain cooked food items at an appropriate and safe temperature and to serve fresh food items quickly to customers. This is particularly the case in quick service restaurants, where customers expect to receive their food with a minimum delay. Of course, customers also expect the food to be of consistent high quality and served at the appropriate temperature. The rate of customer demand typically varies at different times of day, with some periods such as lunch having extremely high rates of demand. In order to meet peak demand and provide quick service, certain food items must be precooked and stored under conditions suitable to preserve freshness and safety and maintain the food items at the appropriate temperature for service.  
         [0003]     Typical foods of interest in quick service restaurants include sandwiches composed of a bun, roll or other bakery-cooked bread product and a sandwich filling that is cooked on site at the quick service restaurant. Typical sandwich fillings include hamburger patties, grilled or breaded and fried chicken patties or filets, breaded fish filets, sausage patties, bacon, Canadian bacon and eggs. The restaurant may also offer products other than sandwiches, such as French fries, chicken strips and nuggets, and individual pies.  
         [0004]     To provide both quick service and food with a fresh taste and appearance, it is often desirable to cook a quantity of individual food items such as sandwich fillings, store them in a holding area, and incorporate them on a first-in, first-out into individual sandwiches as orders are placed. To ensure consistent quality, the cooking and preparation processes must be performed uniformly and, if food items in the holding area are not sold prior to the expiration of a preset period of time, they are discarded. Because of the high volume of sales in a typical quick service restaurant, even a small increase in the efficiency of the handling of cooked food items, and a small decrease in the number of food items which must be discarded, can result in considerable savings of time and expense.  
         [0005]     A need exists for a system and method that can automatically monitor the types and quantities of food items that have been cooked and are in the holding area at any given time, can alert restaurant personnel when the inventory of a particular item is nearing exhaustion and that more of such items should be cooked, and can alert personnel when food items in the holding area must be discarded. It would be desirable for the system to manage food items in the holding area so that they are utilized on a first-in, first out basis, and to manage movable trays of cooked food no matter where they are located in the facility.  
       SUMMARY OF THE INVENTION  
       [0006]     In accordance with the present invention, a system is provided for managing the handling of food items in a restaurant. The system includes at least one cooking station such as a grill or fryer, at least one cooked food item holding device, means for identifying the type and quantity of the food items, data storage means associated with the cooked food item holding device, and a controller for receiving data from the data storage means. The cooked food holding device may be any suitable tray, bin, basket, plate, or other movable container, open or closed, or a fixed or moveable holding area such as a defined area on a countertop or a cart.  
         [0007]     In accordance with another aspect of the present invention, the cooked food holding device is a movable holding device such as a tray which has an RFID tag. A cooked food storage area is provided for receiving and holding the movable holding device. The cooked food storage area is equipped with an RFID sensor for detecting and reading the RFID tag.  
         [0008]     In accordance with another aspect of the invention, a system is provided with at least one cooking station, a plurality of trays each having an RFID tag, a heated cabinet with a plurality of slots for receiving and holding the trays, each slot being equipped with an RFID interrogator for reading data from and writing data to the RFID tag on a tray inserted into the slot, apparatus to identify automatically the type and quantity of food items, and a controller for receiving and storing data from the identification apparatus and the RFID interrogator and for applying a time stamp to the RFID tag when a tray is placed in a slot.  
         [0009]     In another aspect of the invention, the cooked food storage area is a heated cabinet with a plurality of slots for receiving and holding a plurality of trays. Each slot is equipped with a weight sensor such as a load cell for measuring the weight of the food on the tray and detecting changes in weight as food items are removed.  
         [0010]     In another aspect of the invention, a machine vision system including a camera is used to identify automatically the type and quantity of food items at a cooking station or on a tray. In still another aspect of the invention, a weighing system including a load cell is used to identify automatically the type and quantity of food items at a cooking station or on a tray.  
         [0011]     In another aspect of the invention, an RFID tag printer is connected to a point of sale terminal for printing RFID tags which are affixed to food containers.  
         [0012]     In yet another aspect of the invention, a method for managing the handling of food items in a restaurant includes the steps of preparing a plurality of one type of food item, identifying the type and quantity of the prepared food items, providing at least one prepared food holding device, placing the prepared food items in the holding device, recording the time at which the food items were placed in the holding device, and tagging the holding device with an RFID tag to identify the type and quantity of food items and the time.  
         [0013]     In still another aspect of the invention, the method includes providing a food storage area for receiving a plurality of food holding devices, and establishing an order for utilizing the food items from the holding device on a first-in, first-out basis. In accordance with another aspect of the invention, a signal is generated when the time elapsed since the recorded time exceeds a preset limit, indicating that the food items should be discarded.  
         [0014]     In still another aspect of the invention, the method includes storing the number of food items ordered by and delivered to customers at a point of sale terminal, and the number of food items identified on an RFID tag but not sold, and calculating the percentage of food products sold versus the percentage to waste.  
         [0015]     In another aspect of the invention, the type and number of food items are entered manually by an operator. In yet another aspect of the invention, the type and quantity of food items are automatically determined by a machine system such as a machine vision system including a camera or a weighing system including a load cell. In still another aspect of the invention, the type and quantity data are input by a combination of manual and automatic means. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a schematic floor plan of a restaurant utilizing the system of the invention.  
         [0017]      FIG. 2  is a flow chart of the basic steps in the method of the invention.  
         [0018]      FIG. 3  is a schematic elevation view of grill cooking station for use with the invention.  
         [0019]      FIG. 4  is a schematic elevation view of a fryer cooking station for use with the invention.  
         [0020]      FIG. 5  is a front elevation view of a cooked food holding cabinet for use with the invention.  
         [0021]      FIG. 6  is an example of a food holding tray with RFID tag of the invention.  
         [0022]      FIG. 7  is a view of a computer display screen of a vision system for identifying food items on a grill cooking station. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     The system and method of the invention provide convenient, efficient and automated management of all aspects of cooked food handling in a quick service restaurant. As used herein, “handling” refers to the production, storage and delivery of cooked food items.  
         [0024]      FIG. 1  illustrates one example of a floor plan of a restaurant equipped with the system of the invention. The restaurant includes kitchen area  2  and customer service area  4 . Uncooked food items are stored in storage cabinet  6  which may be, for example, a refrigerator, freezer or pantry cabinet. Kitchen area  2  includes two cooking stations, a fryer  8  and grill  10 . Fryer  8  is used for preparing food items such as French fries, breaded chicken patties and filets, breaded fish filets, fried pies and the like. A typical restaurant may have a 2- or 3-vat fryer. Food items are placed in baskets that are lowered into the vat of the fryer for cooking. Grill  10  is used for cooking food items such as hamburger patties, grilled chicken, sausage patties, bacon, Canadian bacon, and eggs. Grill  10  may be a traditional flat, open grill, or a double-sided “clamshell” type that cooks food items on both sides simultaneously. Of course, other types of cooking stations may be used with the system and method of the invention depending on the type of food being prepared, including, without limitation, ovens, pizza ovens, conveyor ovens, pasta cookers, and induction cooktops.  
         [0025]     The identity and quantity of food items can be determined in a number of ways, including by a human operation, by a machine, or by a combination thereof. The machine may include a machine vision or camera device, optical detectors, and/or weighing apparatus, for example.  
         [0026]     In the illustrated embodiment, a vision system  12  including a camera  14  is mounted adjacent grill  10  in a position where camera  14  can capture an image of the entire cooking surface of grill  10 . Preferably, camera  14  is located in a camera enclosure  16  which protects it from smoke, grease and heat. Camera enclosure  16  is preferably mounted on the ceiling of kitchen area  2 . See  FIG. 3 . Vision system  12  is utilized to determine the type and number of food products on a grill as hereafter described.  
         [0027]     Food transfer stations  18 ,  20  are located adjacent to fryer  8  and grill  10 , respectively. Trays  22  are placed on food transfer stations  18 ,  20 . As food is cooked in fryer  8  and on grill  10 , it is removed and placed on trays  22 . Each tray  22  has an embedded or attached RFID tag  24 . Each tray  22  is assigned a unique identifying number which is stored on the RFID tag  24 . An RFID sensor  25  is located at each food transfer station. A manual data entry device such as a keypad (not shown) may also be located at each food transfer station. See  FIG. 6  for an example of a tray  22 .  
         [0028]     Each RFID tag  24  is preferably a passive type RFID device. Passive RFID devices are small, inexpensive and do not require their own internal power source such as a battery. Such a device includes a transponder with an internal antenna and a CMOS integrated circuit including a small amount of non-volatile memory such as EEPROM. The memory can store both the unique identifying number and other data. The RFID tag is used in conjunction with an RFID sensor (sometimes called an interrogator), which includes an antenna, a transceiver and a decoder. The sensor emits a radio frequency (RF) signal. When the RFID tag is in close enough proximity to the sensor so that it passes through the RF field, the RFID tag is activated. The RF signal induces a small electrical current in the tag&#39;s antenna providing just enough power for the integrated circuit to operate. The tag transmits the data in its memory, which is read by the sensor, decoded and passed to the host computer. The sensor may also write data to the memory in the RFID tag.  
         [0029]     RFID tag  24  may be a permanent type RFID device which is embedded in the material of tray  22  or permanently affixed thereto, or it may be clipped or otherwise temporarily attached to tray  22 . In the alternative, RFID tag  24  may be a disposable RFID device which is replaced with each new batch of food items. An RFID tag printer (not shown) may be provided to produce disposable RFID tags.  
         [0030]     Food storage cabinets  26 ,  28  are provided for receiving and storing cooked food items from fryer  8  and grill  10 , respectively. Preferably, food storage cabinet  26  is adapted for holding fried foods, and food storage cabinet  28  is adapted for holding grilled food. Trays  22  are removed from food transfer stations  18 ,  20  and are carried to and placed into the appropriate cabinet  26  or  28 . Cabinets  26 ,  28  are open on opposite sides, and include multiple slots for receiving trays  22 , which are inserted into the slots on the side of the cabinets  26 ,  28  facing the cooking stations. Each cabinet includes a storage cabinet controller  30 . A suitable storage cabinet controller  30  is the Allen-Bradley Micrologix 11 controller available from Rockwell Automation of Milwaukee, Wis. This controller provides built-in Ethernet and serial communications, robust construction, compact size and low cost. It provides multiple digital inputs and outputs, as well as analog inputs suitable for use with load cells for weight measurements.  FIG. 5  shows an example of a food storage cabinet  26 , which is described in more detail below.  
         [0031]     A food preparation table  32  is located adjacent cabinets  26  and  28 . Personnel working at table  32  use tongs or other tools to remove food items from trays  22 , preferably without removing trays  22  from cabinets  26 ,  28 , by inserting the tools into the open side of the cabinet facing table  32  and removing the selected food item. The personnel then complete assembly of the sandwich or other item on food preparation table  32 , and deliver it to service counter  34  for delivery to customers in customer service area  4 . Point of sale (POS) terminals  36  (e.g., cash registers) are located on service counter  34 .  
         [0032]     System controller  40  is located at a convenient location in or near kitchen area  2 . System controller  40  is connected by wire or wireless network connection, for example, an Ethernet network, to vision system  12 , holding cabinet controllers  30  and POS terminals  36 , as well as to other components in the system which will be described below. System controller  40  may run a general production and inventory management program which can interface with the system of the invention, and may also be connected to an off-site central computer system or network (not shown) for a group of restaurants via a network connection. System controller  40  may be a personal computer (PC), server or dedicated controller such as the Allen-Bradley Micrologix 11 discussed above.  
         [0033]      FIG. 2  is a flowchart showing the basic steps in the method of the invention using the system as installed in a restaurant as described above. First, an employee removes the desired food items from the storage cabinet  6  and then transfers them to a cooking station, either grill  10  or fryer  8  as appropriate for the type of food item. The selected food items are then cooked in the grill  10  or fryer  8 , either manually or under automatic control as in known in the art. The system automatically detects the type and number of food items on the grill  10  or in a fryer basket, by means of a vision or weighing operation as explained in more detail below, and transmits the food type and number data to holding cabinet controllers  30  and/or system controller  40 . When the food items are done, an employee transfers them to a food holding device. The food holding device may be any suitable fixed or movable space or volume for holding cooked food items, for example, a tray, bin, basket, plate, carton or other container, open or closed, or simply a defined area on a countertop or cart, but it is preferably a movable device such as tray  22 . In some cases the food holding device may be the same device in which the food items were cooked, for example, a fry basket or a cooking vessel for use in a bain-marie (water bath). Each different type of food item is preferably placed on a separate food holding device such as a tray  22 .  
         [0034]     If only one type of food is being prepared, its type will obviously already be known and its identity can be pre-stored in the system. If there are multiple types of food, the type of food being prepared can be determined by machine, such as a machine vision system as described below, or alternately the type of food may be input by a human operation via a keypad, keyboard or other data entry means located near a cooking station, or via a mobile data entry device such as a personal digital assistant (PDA).  
         [0035]     As illustrated, vision system  12  including camera  14  is used to count the number of items on grill  10 , determine the type of items on the grill  10 , and relay the information to system controller  40  and/or the holding area controllers  30 . The vision system  12  essentially takes a “snap shot” of the grill surface and uses software to analyze the food items. In the case of a clamshell grill, the snap shot is taken when the food is cooked and the grill is opened, and the analysis of the image is performed while the operator is loading the food items into a tray. The software uses pictures that are stored in the vision system&#39;s memory as a reference for determining the type of food. To set up the reference images, a technician takes a picture of each item using the camera  14  and its associated software. Preferably, camera  14  is a color camera, as color facilitates the identification of similar-appearing food item types. In operation, camera  14  scans the entire surface of grill  10  and determines all the food item types thereon.  
         [0036]     Once the food item type and count have been determined by the vision system  12 , the information is transferred to the holding area controllers  30  and/or system controller  40  where a time stamp is applied. This information resides in a database in the controller&#39;s memory until it is written to a tray&#39;s RFID tag, as will be discussed below. The operator removes the cooked food items from grill  10  and loads them onto trays  22  at food transfer station  18  located adjacent grill  10 .  
         [0037]     In the case of a clamshell type grill, instead of using a vision system, a thickness measuring system may be used to identify the type of food items. Typically, each type of food item has a different nominal thickness. A sensor on the movable upper platen of the clamshell grill may be used to measure the nominal thickness of the food items on the grill based on the height of the platen above the lower grill surface when it contacts the food item. That measurement can be compared to stored thickness data in system controller  40  to identify the type of food. A weighing device can be used to determine the number of items on the grill or alternately, a human operator can enter the number of items via a keypad or other data entry device provided near the grill, or via a mobile data entry device such as a personal digital assistant (PDA).  
         [0038]     The vision system described for use with the grill is less suitable for use with the fryer, where the food items are placed into a basket and immersed in oil for cooking and thus not as readily visible to a camera as individual food items on a grill. Thus, a weighing system is preferably used for foods prepared in the fryer. Food transfer station  18  located adjacent fryer  8  preferably includes a weight sensor such as a load cell. An empty tray is placed over the load cell, which weights the tray and sends a weight signal to system controller  40 . System controller  40  tares out the tray weight, i.e., resets the weight value to zero. The operator removes a fry basket of cooked food items from fryer  8 , and after allowing excess oil to drain, dumps the food items onto the tray  22 . The load cell detects the weight of the food items and sends that weight signal to system controller  40 , which determines the number of food items present based on stored food item weight profile data. See  FIG. 4  and further discussion below.  
         [0039]     The weight information may be used to automatically control other operations. For example, when a basket of cooked French fries is dumped into a salting tray, the RFID tag is read and compared to previous information sent from the weighing system. The correct amount of salt is distributed on the fries. Additionally, the process time information can be communicated to system controller  40  and/or a remote central computer for production/waste monitoring.  
         [0040]     Once the food item type and count have been determined by the weight system, the information is transferred to holding cabinet controllers  30  and/or system controller  40  where a time stamp is applied. This information resides in a database in the system controller&#39;s memory until it is written to a tray&#39;s RFID tag, as will be discussed below.  
         [0041]     In addition, or in the alternative, each fry basket may be equipped with an RFID tag. This tag will store an identification number, the type of food (e.g., French fries) and the fill quantity of the basket. This data is transferred to a controller for the fryer which will initiate the appropriate cook cycle for the food product, controlling such variables as oil temperature and time of frying. The data can also be used to control an automatic salting device after the French fries are cooked.  
         [0042]     An employee carries tray  22  from the food transfer station  18  or  20  to the holding area and places it into a slot in the appropriate holding cabinet  26  or  28  for the type of food item on the tray  22 . When the tray  22  is placed in a slot, a sensor (shown in  FIG. 5 ) on each slot in the cabinet detects the RFID tag  24  on the tray  22  and reads the data thereon, specifically the tray identification number. This data is transmitted to the holding cabinet controller  30 , which evaluates the tray number and associates it with the grill or fryer location. The food type and food count information from the associated grill or fryer, which was previously received from vision system  12  or system controller  40  and stored in the holding cabinet controller&#39;s database, is sent to the memory in the tray&#39;s RFID tag  24 . If the memory transfer has an error, the data is sent directly from the system controller  40  to the holding cabinet controller  30  via the network. Thus, the holding cabinet controller  30  gets the information from the counting system and ensures that the correct information is on the tray&#39;s memory when the tray  22  is placed into the holding area.  
         [0043]     In the alternative, instead of using a writable RFID tag and transferring food item type and count data to the tag for each batch of food items as described above, RFID tag  24  may have a fixed identification number and be permanently associated with a specific type and quantity of food items and, if desired, with specific time data (e.g., cooking time or holding time) for that type and quantity of food items. The food type and count data may be permanently stored in the memory on RFID tag  24 , or controller  40  may associate the tag identification number with food type and count information stored in a database of controller  40 .  
         [0044]     When a tray  22  is inserted and the food type and quantity have been determined, cabinet controller  30  can automatically initiate heating at a temperature appropriate for that food type. In an alternate mode of operation, if the slot is already at a particular temperature, the controller can signal a warning to a user if he inserts a tray with food items requiring a different temperature set point.  
         [0045]     Alternately, the slot in the holding area may have a load cell for weighing the tray to determine the number of food items in the tray. The load cell detects the weight of the food items and sends that weight signal to holding area controller  30 , which determines the number of food items present based on stored food item weight profile data. For example, the food items may be 10:1 hamburger patties with a nominal weight of 1/10 pound each, 4:1 hamburger patties with a nominal weight of ¼ pound each, etc. The database in controller  40  may be programmed to account for the typical difference between nominal pre-cooked and post-cooked weight of the food items.  
         [0046]     The holding area controller  30  is pre-programmed with a time limit for holding each type of food in the storage area, and periodically checks to see if the preset time has been exceeded. If it has, controller  30  sends a signal by, e.g., turning on a red light or LED indicator above the slot where the expired food is located and/or activating an audible alarm. This indicates to the restaurant personnel that those food items should be removed and discarded.  
         [0047]     Employees working at food preparation table  32  remove food items from the trays as needed to fill customer orders. A load cell located below each tray detects the change in weight caused by removal of a food item and updates the count of remaining food items in that tray. If the number of food items falls below a preset number, the computer sends a signal to alert a staff member to cook more of that type of food. The preset number may vary depending on the time of day to accommodate periods of varying demand.  
         [0048]     If there are multiple trays  22  of the same type of food items in the holding cabinets  26 ,  28 , cabinet controllers  30  can signal which tray  22  should be used first based on the time stamp applied to each RFID tag  24  and the time remaining until expiration of the usable life of the product. The signal may be via LEDs or lights above each slot in the cabinet (see  FIG. 5  and discussion below) or another type of display.  
         [0049]     As shown in  FIG. 3 , vision system  12  is provided at grill  10 . Vision system  12  includes camera  14 , camera software and, if needed, supplemental lighting (not shown). Camera  14  is preferably mounted on the ceiling above grill  10  so that camera  14  is out of the way but still has a clear view of the entire grill surface. Camera  14  may be enclosed in an enclosure  16  with a transparent panel to protect it from smoke, heat and grease. A suitable vision system is available from Banner Engineering Corp. of Minneapolis, Minn., which is a self-contained camera system with a built-in processor, an Ethernet connection and an output for connecting a television monitor. The camera operates with Banner&#39;s PresencePLUS software. The inspection time for this camera system is approximately one second. A standard grayscale camera may be used in basic applications. However, in a restaurant that serves a variety of food items having similar sizes, shapes and appearances, a color camera is preferred since color makes it easier to distinguish the different types of food items.  
         [0050]     Camera  14  may be positioned slightly off to one side of grill  10  to avoid smoke and grease. The field of view of camera  14  is preferably slightly larger than the grill size. Depending on the type of camera used and the ambient lighting in the kitchen area, supplemental lighting may be require to ensure consistent operation of the vision system. For example, standard fluorescent lighting may be adequate, but with some cameras the ballast used to drive the fluorescent tubes may need to be a high frequency ballast rather than a standard magnetic ballast.  
         [0051]     The vision system software includes analysis tools that use information from an image captured by the camera to create size, shape and count measurements. These tools use so-called “blob” processing to identify various food items with different sizes and then separate those that are the same size. Blob analysis consists of a series of processing operations and analysis functions that produce information about any two-dimensional shape in an image captured by the camera. It is useful for finding “blobs” whose spatial characteristics satisfy certain criteria and find their size and number. As such, it is well suited to identifying and counting food items of known shapes and sizes. A “blob tree” is defined in the software that includes all of the blobs for the various types of food items with which the system is used. A “roundness” parameter separates square patties from round patties.  
         [0052]      FIG. 7  shows a sample screen display  70  on a monitor connected to vision system  12 . Display  70  is generated by the camera software, and shows the shapes and sizes of a variety of food types  72  on the surface of an image of a grill  74 . The count of each type of food item  72  may be displayed in boxes  76  at the bottom of screen display  70 , and control options may be displayed in box  78  at the right side of screen display  70 . Of course, the layout and functional options of screen display  70  may be varied and adapted as desired for various types of restaurants. The following table describes some types of food products that may be identified and counted by vision system  12  based on their size, shape and/or color:  
                           TABLE I                                   Size/shape       Product Type   Physical Size   Color   varies?                   10:1 burger patty   3″ diameter   Brown beef   No       4:1 burger patty   4″ diameter   Brown beef   No       Grilled chicken   3″ diameter   White chicken   Yes           cooked in ring   meat       Sausage patty   2½-3″ diameter   Brown pork   No       Bacon   1 × 4″   Reddish brown/   Yes               white stripes       Canadian bacon   2½-3″ diameter   Reddish brown   Yes               pork       Steak patty   3″ square   Brown beef   No       Round eggs (in   3″ diameter   White/yellow   No       ring)       Folded eggs   2½″ square   White/yellow   Yes       Scrambled eggs   Random   White/yellow   Yes                    
 As evident from the above table, some food types, e.g., scrambled eggs, are more challenging for a vision system to distinguish and may require more sophisticated software tools. 
 
         [0053]      FIG. 4  shows fryer  8  and its associated food transfer station  18 . A weighing area  42  is located at food transfer station  18 . Weighing area  42  utilizes a load cell  44  located under the surface of weighing area  42 . Load cell  44  and weighing area  42  are located to the side of fryer  8  to reduce the chance of damage to load cell  44  from hot oil. A suitable load cell is model M2750-MK21 available from Muse Measurements of San Dimas, Calif. This model is compact and of stainless steel construction so that it can withstand the harsh operating environment and frequent washdowns typical in a restaurant kitchen. The load cell&#39;s analog output is connected to an analog input of system controller  40 .  
         [0054]      FIG. 5  illustrates an exemplary food storage cabinet  26  which includes slots  50  for receiving and holding trays  22 . Trays  22  are sized to fit in slots  50  to ensure quick ingress and egress from either side of storage cabinet  26  during food service. Storage area controller  30  may be mounted on top of cabinet  26  as shown or at another convenient location. Controller  30  controls all aspects of the cabinet operation including storing data regarding food type, food temperatures and heating times. Data may be manually entered by an operator, received from vision system  12 , weighing area  42 , or system controller  40 , or obtained from RFID tags  24  on trays  22 .  
         [0055]     Cabinet  26  may be provided with a keypad, buttons or other devices for manual data entry, and/or a touch screen for combined data display and entry. If a touch screen is provided, it may be used by an operator to enter into memory in controller  30  the individual foods that will be kept in cabinet  26  and their respective parameters such as heating times and temperatures. Either the entire cabinet or individual slots may be preprogrammed to activate heaters at specified temperatures and for specified lengths of time. A touch screen or other control may be used to change modes of operation, such as between breakfast and lunch menu modes, or to accommodate special or seasonal food items.  
         [0056]     Each slot  50  of cabinet  26  is equipped with an RFID sensor  52  which activates and detects a signal from RFID tag  24  on tray  22  when tray  22  is inserted into slot  50 . RFID sensor  52  is positioned, and its range of operation selected, so that it detects only RFID tag  24  on a tray  22  that is placed into slot  50  with which RFID sensor  52  is associated, so that it will not erroneously detect, for example, a tray  22  placed in an adjacent slot  50  or a tray  22  being moved near cabinet  26 . Cabinet controller  30  recognizes that RFID tag  24  is associated with a particular tray  22  based on that tray&#39;s unique identification number which is stored in the memory of RFID tag  24 , which in turn is associated with a particular type and quantity of food items that were cooked at a particular time. The latter association is based on data obtained from the system controller  40 , vision system  12  and/or weighing area  42 .  
         [0057]     Each slot  50  may also be equipped with a weight sensor  54  to measure the weight of tray  22 . As food items are removed from tray  22  by personnel working at food preparation table  32  to fill customer orders, the weight will be reduced. Based on the known nominal weight of the individual food items, cabinet controller  30  can calculated the number of food items remaining. If that number falls below a preset number, controller  30  will signal the operator to cook more of that type of food item. Controller  30  may also receive data from POS terminals  36  to calculate and predict the rate of customer demand and automatically change the preset threshold as necessary to meet demand during peak sales periods and eliminate waste when demand is slowing.  
         [0058]     The time elapsed since insertion of a tray  22  into slot  50 , or alternately, since the time the food items were cooked and removed from the cooking station, is monitored by controller  30  and displayed by LEDs  56  above each slot  50 . The colors of LEDs  56  indicate the remaining usable length of time before expiration. For example, the LED color may be green, indicating approximately from 100% to 26% usable product life remaining, yellow for approximately from 25% to 0% usable life remaining and red for usable life expired. The LEDs may flash when the usable life has expired, and in additional an audible alert such as a buzzer may be activated. If there are multiple trays  22  of the same type of food items, the operator can easily scan the LEDs and see which tray to use first, e.g., to use a tray from a slot with a yellow LED before one with a green LED, so that the food items can be utilized on a first-in, first out basis to ensure freshness and reduce waste. Of course, a digital numeric display of time elapsed or remaining may be provided. For example, a touch screen or other display device may display an identification of each food in each slot  50  of cabinet  26  to permit an operator to read the location and status of the food in the respective trays  22 , and may also show the time that each tray  22  has been held or other information about the food. However, the simple color LED scheme provides a quicker indication to the operator of the relative times applicable to each slot.  
         [0059]     The RFID sensing capability of cabinet  26 , controlled by cabinet controller  30 , allows the automatic detection of tray insertion time, automatic heating, identification of the type of food items, the sequence in which food items should be used, and an indication of when food items must be discarded. Automating these functions reduces operator error, saves time, reduces waste and assures consistent quality of the food products. If an operator partially slides a tray  22  out of slot  50 , e.g. to check the contents visually or to remove a food item for use at food preparation table  32 , the RFID tag and sensor will allow timing and heating to continue when tray  22  is placed back in slot  50 . RFID tag  24  can be detected some distance away from RFID sensor  52 , e.g. one inch, and controller  30  can therefore continue to monitor tray  22  for timing and heat control. Further, because the RFID tag is associated with an individual tray, the system can track that tray even if it moved to a different slot  50  in cabinet  26 , to a different cabinet, or to other locations within kitchen  2  if RFID sensors are provided at those locations.  
         [0060]     An exemplary tray  22  for use with the system is shown in  FIG. 6 . Tray  22  is configured to accept a variety of food types and to fit easily into slots—in cabinets  26 ,  28 . Tray  22  may be of any suitable material, but is preferably made of metal, for example, aluminum, which is durable, lightweight and allows rapid heat transfer to the food items therein. Tray  22  may be either reusable or disposable, e.g., made of foil, cardboard or paper. The ends  60  of tray  22  are preferably sloped to facilitate removal of food items. RFID chip  24  may be located at any convenient place on tray  22  so long as RFID tag  24  will be in range of RFID sensor  52  when tray  22  is inserted into a slot  50 , but is preferably located at one end under lip  62  to protect it from damage during handling of the tray. RFID tag  24  may be embedded in the material of tray  22  or attached either permanently or removeably to its exterior.  
         [0061]     System controller  40  interfaces with POS terminals  36  to provide various additional functions. For example, POS terminals  36  may send data of sales to system controller  40 , which compares the number of each type of food item actually sold and delivered to customers with the number of food items prepared at fryer  8  and grill  10  and/or stored in holding cabinets  26 ,  28  to determine the percentage of waste (number of items discarded).  
         [0062]     RFID label printers may be provided at service counter  34  and/or food preparation table  32 . These printers are used to printing RFID labels for some or all of the components of a customer order. The RFID labels are adhered to the product packaging to enable the tracking of product flow and order readiness as well as providing instructions for special orders (e.g., no pickles on a hamburger). For the special order application, RFID tag readers are positioned at food preparation table  32  to read the RFID tag on a specific sandwich packaging. A light indicator system or display assists the order assembler with information on which condiments to place on the sandwich.  
         [0063]     For order readiness applications, an RFID reader may be positioned at other areas within kitchen  2  for completed order components. The readers are used to verify when all tagged components of an order are ready for pick-up and delivery to the customer.  
         [0064]     While the invention has been described with respect to certain preferred embodiments, as will be appreciated by those skilled in the art, it is to be understood that the invention is capable of numerous changes, modifications and rearrangements and such changes, modifications and rearrangements are intended to be covered by the following claims.