Abstract:
In one embodiment of the present invention, a system includes a radio frequency identification (RFID) reader that is configured to obtain identification information from a plurality of RFID tags respectively attached to the plurality of items. A computer is configured to receive the identification information, and use the identification information to identify the items having a RFID tag attached thereto, and determine a percentage of a desired type of item with respect to the plurality of items.

Description:
RELATED APPLICATION 
     This application is related to the following copending and commonly assigned patent application, which is incorporated herein by reference in its entirety: “Systems and Methods for Indicating a Quality of Grouped Items,” having application Ser. No. 11/515,789, and filed on Sep. 6, 2006. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention relate to the field of collecting recyclable materials and, more particularly, to systems and methods for determining the composition and purity of a quantity of recyclable materials. 
     2. Background Description 
     To meet the growing problem of post-consumer goods disposal, many recyclable post-consumer goods are collected from the curbside and sent to a material recovery facility (MRF). MRFs are facilities where mixed recyclable materials are sorted and baled for sale, and generally serve as drop-off and gross-sorting (and limited processing) points for recyclable materials, so that sorted recyclable materials can be transported, for example, to a facility for subsequent processing. 
     Recyclable materials generally enter a MRF either in a single stream or dual stream. A single stream MRF may receive a mixture of commingled containers that may be made of glass, plastics, and/or metals, and fiber material that may include old news print (ONP) (e.g., newspaper and newspaper inserts), old corrugated paper (OCC), old telephone directories (OTD), old magazines (OMG), junk mail and/or office paper. A dual stream MRF generally has separate commingled container and fiber material streams. 
     Generally, recyclable materials arriving at MRFs can be sorted into individual material categories, such as glass, plastic, steel, aluminum, paper, cardboard, and the like. In addition, clear glass can be separated from colored glass, and plastics can be separated by type and color. Materials such as plastic, steel, aluminum, paper, and cardboard, can then be baled in a standard manner. Bales can be stored at an MRF until a buyer, such as a glass plant or paper recycling facility, purchases them. 
     While traditional MRFs typically utilize a dual stream configuration, the desire to reduce labor and other operational costs has been an impetus behind the trend toward single stream MRFs. However, sorted recyclable materials produced by single stream MRFs can have a higher contamination level than sorted recyclable materials from dual stream MRFs. Thus, for example, bales of sorted plastic from a single stream MRF may have an average purity of 95% by weight, whereas bales of sorted plastic from a dual stream MRF may have an average purity of 97% by weight. 
     In known systems, bale-specific information regarding purity is not generally ascertainable until you break open the bale. Accordingly, bales are typically sold based on physical accessibility of the bales within a MRF at the time of shipment. Lack of information pertaining to the purity of the bales can result in bales being rejected by the purchaser and returned to a MRF, or downgraded by the purchaser. This forces MRFs to absorb the cost associated with the returned bale(s), or to refund a portion of the sales price, particularly for bales emanating from single stream MRFs that generally have higher contamination rates than bales emanating from dual stream MRFs. 
     We have discovered that systems and methods for accurately and efficiently measuring the composition and purity of a bale and providing verifiable bale-specific information are needed. Such systems and methods can be used to ensure the purity of bales, increase customer satisfaction, and generate price premiums for the bales that are determined to have, for example, a higher than average level of purity. 
     SUMMARY OF EMBODIMENTS OF THE INVENTION 
     Embodiments of the present invention relate to systems and methods for measuring the purity of bales of recyclable material. Various embodiments of the present invention use radio frequency identification (RFID) technology to determine the composition of a bale of waste items and to calculate the purity of a bale of recyclable material. 
     In one embodiment of the present invention, a system includes a radio frequency identification (RFID) reader configured to obtain identification information from a plurality of RFID tags respectively attached to at least a portion of a plurality of items. A computer is configured to receive the identification information, and use the identification information to identify the items having a RFID tag attached thereto, and determine a percentage of a desired type of item with respect to the plurality of items. The system also include an optical counter for counting a total number of the plurality of items. 
     The computer calculates a measurement of purity that includes a percent weight of items of the desired type among the plurality of items with respect to a total weight of the plurality of items. The system also includes or utilizes a scale for measuring the total weight of the plurality of items. 
     The computer is further configured to calculate a total weight of items of the desired type by identifying each of the items of the desired type using the identification information and determining a combined weight of each of the identified items. The computer is also configured to calculate a total weight of items of the desired type by identifying each item other than the items of the desired type among the plurality of items using the identification information, and subtracting a weight of each of the identified other items from the total weight of the plurality of items. 
     The system also includes or utilizes a baler that creates a bale comprising the plurality of items. The computer includes or utilizes a repository for storing identification information of a bale that includes the plurality of items, and, in connection with the identification information of the bale, the percentage of the desired type of item with respect to the plurality of items. 
     The system also includes or utilizes a RFID tag programmer configured to write the percentage onto a RFID tag associated with the bale. The system also includes or utilizes a second RFID reader that reads the identification information of the bale from the bale RFID tag, wherein the computer receives the identification information and updates the repository indicating that the bale is no longer available. 
     In another embodiment of the present invention, a method includes reading identification information from a plurality of RFID tags respectively attached to at least a portion of a plurality of items, and receiving the identification information at a computing device that identifies each of the items having a RFID tag attached thereto. A percentage of a desired type of item is calculated with respect to the plurality of items. The method also includes baling the plurality of items to form a bale, and writing the calculated percentage onto a RFID tag associated with the baled items. The percentage pertains to a quantity of items of the desired type among the plurality of items with respect to a total quantity of the plurality of items. 
     The method also includes weighing the plurality of items. When weighing the plurality of items, the calculated percentage pertains to a percent weight of items of the desired type among the plurality of items with respect to a total weight of the plurality of items. 
     In addition, the method includes attaching to the bale a RFID tag having the calculated percentage written thereon, and storing in a data repository the calculated percentage. The data repository can be updated to reflect that a particular bale is no longer available. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The Detailed Description of the Invention, including the description of various embodiments of the invention, will be best understood when read in reference to the accompanying figures wherein: 
         FIG. 1  is an exemplary block diagram of an embodiment of a purity measurement system; 
         FIG. 2A  is an exemplary data repository of a serial number contained on a radio frequency identification (RFID) tag; 
         FIG. 2B  is an exemplary data repository providing product information respectively associated with the RFID tag serial numbers shown in  FIG. 2A ; 
         FIG. 3A  is a 96-bit EPC™ structure that can be used in conjunction with one or more embodiments of the present invention; 
         FIG. 3B  is an exemplary repository that utilizes at least a portion of the data contained in  FIG. 3A ; 
         FIG. 4  is an exemplary arrangement of an optical reader that can be used in conjunction with one or more embodiments of the present invention; 
         FIG. 5  is an exemplary data repository that contains bale specific information; and 
         FIG. 6  is an exemplary flow chart illustrating a method for measuring the purity of bales of recyclable materials. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a block diagram depicting purity measurement system  100  that can be used in a material recovery facility (MRF). System  100  includes general purpose computer  120 , which in turn includes purity measurement software  122  and application data repository  124 . System  100  also includes RFID reader-counter  128 , and tag programmer  126 . 
     Computer  120  can include industry standard components (not shown), such as a user interface (e.g., a keyboard and a mouse) and display (e.g., a monitor), a processor, a storage device such as a standard hard disk, a CD-ROM and/or CD-RW drive(s), a clock device for providing timestamp data, and/or standard interfaces (e.g., USB ports). 
       FIG. 1  also includes final sort container  130 , scale  136 , and baler  138 . Container  130  contains waste items  132 , which can be glass containers, plastic containers, aluminum containers, ferrous items, fiber products such as paper and cardboard, and/or other types of waste items. Container  130  can be any type of container for collecting waste items  132 ,  132   a ,  132   b.    
     Waste items  132  can have item RFID tags  134  affixed. Each of RFID tags  134  can contain identification information, such as a digital serial number identifying the corresponding recyclable item, and/or information regarding the type of the item. RFID reader-counter  128  can be used to count items  132  going into container  130 , and, read tags  134  in order to extract the identification information contained therein. RFID reader-counter  128  can send the extracted identification information to computer  120 , which utilizes purity measurement software  122  and repository  124  to obtain information regarding waste items  132 , such as item weight and type of material. 
     Reader-counter  128  can be a commercially available RFID tag reader system, such as the TI RFID system, manufactured by Texas Instruments Incorporated (Dallas, Tex.). RFID reader-counter  128  is positioned so that RFID tags  134  of waste items  132  are within its effective range. Waste items  132  are used to form or generate a bale  140 . Multiple bales of waste items can be stored at a MRF as inventory before they are sold and removed from the MRF. 
     Purity measurement software  122  uses repository  124  to analyze identification information obtained from tags  134  using RFID reader  128 . Repository  124  can include information regarding different types of waste items  134 , such as item weight and type of material (e.g., glass container, plastic container, aluminum container, or paper product). In addition, repository  124  can also include any other information, such as information regarding bales stored at the MRF. 
       FIGS. 2A and 2B , taken together, illustrate one example of repository  124 .  FIG. 2A  is a table indexed by serial numbers  202  and associating serial numbers  202  with item type indexes  204 .  FIG. 2B  is a table indexed by item type indexes  204 . The table in  FIG. 2B  contains information relating to weight  206 , type of material  208 , and item type  210  for various types of items  132 . Therefore, in this example, using a serial number  202  identifying a recyclable item, software  122  can cross-reference repository  124  to determine the weight  206  and type of material  208  of the recyclable item. If the serial number is 00004, as shown in  FIG. 2A , software  122  can determine that the corresponding item  204  is a 12 ounce aluminum can  210  weighing 5 grams  206 . 
     Implementation of repository  124  is not limited to the example illustrated in  FIGS. 2A and 2B ; various implementations of repository  124  can be used to achieve the same results. The implementation of repository  124  may also vary depending on the type of identification information contained in RFID tags  134 . 
     For example,  FIG. 3A , generally at  300 , illustrates the Electronic Product Code (EPC), which is a standard format for storing identification information in RFID tags. The EPC is designed to replace the Universal Product Code (UPC) currently utilized in conjunction with barcodes. An EPC-96 code has four components: 
     (a) an 8-bit tag version number  302 , indicating the tag type (e.g., 96-bit EPC Class 1); 
     (b) a 28-bit domain manager identifier  304 , such as a number specifying the entity that administers the tag code (e.g., “ABC Co.”); 
     (c) a 24-bit object class identifier  306 , such as a number specifying the type of product the RFID tag is attached to (e.g., “16 oz. Coca-Cola bottle”); and 
     (d) a 36-bit unique identifier  308 , which is a number that, in combination with the other EPC components, uniquely identifies the tag (and object). 
     If RFID tags  134  utilize, for example, the EPC as illustrated in  FIG. 3A , or a similar or related technique, repository  124  can be implemented accordingly. For example, repository  124  can include a table as illustrated in  FIG. 3B , containing entries indexed by the 28-bit domain manager identifier  304  and the 24-bit object class identifier  306 . Entries in the table can also include weight  206  and type of material  208  associated with a certain type of recyclable item. Therefore, in this example, after receiving an EPC-96 code containing domain manager identifier  304  representing Company B and object class identifier ( 306 )  1 , software  122  can cross reference the table in  FIG. 3B  and determine that the corresponding item is a 12 ounce aluminum can weighing 5 grams. 
     Certain waste items, such as items  132   a ,  132   b  illustrated in  FIG. 1 , may not have RFID tags  134  respectively attached thereto. For example, paper products, such as newspaper and/or cardboard, may typically not have RFID tags  134  attached thereto. For these items, as illustrated in  FIG. 4 , an optical counter  402  can be utilized to count the number of waste items  132  that will be included in any particular bale. An optical counter  402 , such as the MSS Sapphire™ or MSS Aladdin™ optical sorters, manufactured by MSS, Inc., Nashville, Tenn., can be used. When a MSS Sapphire™ or MSS Aladdin™ optical sorter is used, optical counter  402  can be arranged to receive items from conveyor system  404 . When items  132 ,  132   a ,  132   b  move toward container  130  on a conveyer system  404  to be collected and baled, optical counter  402  can be utilized to count items  132  having RFID tags  134  affixed thereto, as well as items  132   a ,  132   b  that do not have an RFID tag affixed thereto. 
     Scale  136  can be used to weight items  132 ,  132   a ,  132   b . Scale  136  can be a general industrial weighing scale, such as the Siltec WS2000L, distributed by Precision Weighing Balances (Bradford, Mass.). 
     Returning now to  FIG. 1 , baler  138  can be used to transform loose items  132  to a baled commodity, as represented by bale  140 , upon which a bale RFID tag  142  can be affixed. Baler  138  can be any standard equipment that is used to compress and bind a recyclable material, such as aluminum, plastic or paper items  132 ,  132   a ,  132   b . Baler  138  can be, for example, a 1060XDVB Baler by Wastecare Corporation (Atlanta, Ga.), which is an industrial, high-capacity, high-volume baler. Bale  140  includes items  132 ,  132   a ,  132   b  that are bound tightly or wrapped, as is the industry standard for recyclable materials. Bale RFID tag  142  is an RFID tag device that can be written by tag programmer  126 . Tag programmer  126  can be a reader/writer device, such as the SkyeModule™ M1 device supplied by SkyeTek, Inc. (Boulder, Colo.), that can write information to RFID tag  134 . 
     Additionally,  FIG. 1  depicts transport vehicle  110 , which in turn includes computer  112 , RFID reader  114 , communications link  116 , and onboard scale  118 . Vehicle  110  is, for example, a conventional hauling truck that is used to carry and deliver recyclable material bales. Typically, vehicle  110  picks up recyclable material from an originator point such as a MRF and delivers the recyclable material to an awaiting customer, such as a glass or paper recycling facility. 
     Onboard computer  112  can be a general-purpose computer. In some embodiments, computer  112  is a mobile computing device, such as one supplied by Glacier Computing (New Milford, Conn.) or by Mobile Computing Corp. Inc. (Mississauga, Ontario), that is physically integral to vehicle  110 . Computer  112  can include industry standard components (not shown), such as a user interface and display, a processor, a storage device such as a standard hard disk, a CD-ROM and/or CD-RW drives, a clock device for providing timestamp data, and/or standard interfaces (e.g., USB ports) for connecting to reader  114 , scale  118 , and/or communications link  116 . 
     RFID reader  114  can be a commercially available RFID tag reader system, such as the TI RFID system, manufactured by Texas Instruments (Dallas, Tex.). In one or more embodiments, RFID reader  114  is a wired or wireless handheld reader that can be easily moved by an operator of vehicle  110 . In one or more embodiments, RFID reader may be separate from (e.g., removable from) transport vehicle  110 . 
     Communications link  116  can be any standard wired or wireless communications device and/or network that allow data to be exchanged between computer  112  and computer  120 . Onboard scale  118  can be any commercially available scale mechanism, such as the weigh-in motion weighing system, supplied by Mobile Computing Corp. Inc. (Mississauga, Ontario). 
     In operation, RFID reader-counter  128  reads items RFID tags  134  affixed to items  132  before or after they are deposited into final sort container  130 . Software  122  utilizes repository  124  (e.g., as illustrated in  FIGS. 2A ,  2 B, and  3 B) to identify items  132 . Furthermore, software  122  determines a measurement of purity of items  132 , as will be described in connection with  FIG. 5 . In addition, scale  136  can obtain and transmit the combined weight of items  132 ,  132   a ,  132   b  to computer  120 , which can store the combined weight in repository  124 . 
     Baler  138  receives items  132 ,  132   a ,  132   b  within container  130 , and transforms items  132 ,  132   a ,  132   b  into bale  140  in a standard manner. Tag programmer  126  can write bale specific information (e.g., purity measurement determined by software  122 ) onto bale RFID tag  142 . 
     As bale  140  is loaded onto vehicle  110 , bale RFID tag  142  can be read by RFID reader  114 . Onboard scale  118  can also be used to weigh bale  140 . Onboard computer  112  can store the bale specific information and transmit the information to computer  120  via communications link  116 , so that computer  120  can keep track of which bales have been loaded onto vehicle  110  and which bales remain at the MRF. 
     For example,  FIG. 5  is a table  500  containing bale specific information that can be stored in repository  124 . The table includes entries representing bales created in the MRF. An entry in the table can include a bale ID  502 , the type of items  210  in the corresponding bale, the type of material  208  in the bale, the weight of the bale  504 , and a purity measurement  506  (e.g., a weigh percent) for the bale. An entry in table  500  can also include a status field  508  indicating whether the corresponding bale is still in the MRF, or whether it has been shipped out to a buyer. 
       FIG. 6  is a flow chart illustrating a method  600  for measuring the purity of bales and of recyclable materials. The following describes method  600  as being performed using system  100 , generally with reference to  FIG. 1 . 
     At step  610 , a number of waste items  132 ,  132   a ,  132   b  are received. Items  132 ,  132   a ,  132   b  can be the output of a sort process, and therefore can include a high percentage of objects of the same type. For example, items  132 ,  132   a ,  132   b  can include a high percentage of aluminum containers. However, the sort process can be imperfect, so that a relatively small percentage of contaminants or other material types (e.g., glass containers, paper products), with or without RFID tags  134  affixed thereon, can be present. 
     At step  612 , a sort criterion can be established using purity measurement software  122 . A sort criterion can specify one or multiple types of material that is intended to be included in bale  140  that includes items  132 ,  132   a ,  132   b . Measurement of the purity of bale  140  can be based on the percentage of items  132  that satisfy the sort criterion, or the percentage weight of items  132  that satisfy the sort criterion. Waste material or items  132   a ,  132   b  not satisfying the sort criterion may be viewed as contamination. Different purchasers of bales may require different purity levels. For example, one purchaser of aluminum bales may require a maximum of 2% contamination (by weight or item count), while another may be willing to accept up to 5% contamination. 
     At step  614 , items  132 ,  132   a ,  132   b  are identified and counted. RFID reader-counter  128  counts the number of items  132  that have RFID tags  134  affixed thereon, and reads identification information, such as weight  206 , from tags  134 . If desirable, optical counter  402  can be utilized to count the total number of items  132 ,  132   a ,  132   b , as discussed in connection with  FIG. 4 . If optical counter  402  and RFID reader-counter  128  are used in combination, the number of items  132  that have RFID tags  134  attached thereon and the number of untagged items  132   a ,  132   b  can both be ascertained. Identification information obtained by reader-counter  128  can be stored in repository  124 . 
     If it is determined at decision step  618  that the number of untagged items  132   a ,  132   b  is not negligible, then, at step  616 , the total weight of items  132 ,  132   a ,  132   b  can be measured by scale  136  and stored in repository  124 . At step  622 , the weight percent is calculated based on the weight  206  information obtained in step  614  and the total weight obtained in step  616 . 
     For example, if the sort criterion of step  612  is set as plastic containers, software  122  can query repository  124  using the identification information from each RFID tag  134 , to determine the type  210  and weight  206  of each corresponding item. Software  122  can then sum the weight of each of items  132  that is determined to be a plastic container to obtain the total weight of plastic containers. The percentage weight of items that satisfies the sort criterion can then be calculated as:
 
 X= (Σ W   i )/ T   WEIGHT  
 
     where X is the percentage weight of the items that meet the sort criterion; 
     W i  represents the individual weight of each item that meets the sort criterion; and 
     T WEIGHT  is the total weight of all items  132 ,  132   a ,  132   b , as captured by scale  136 . 
     If RFID reader-counter  128  reads and accounts for 10,000 plastic containers, and repository  124  indicates that each container weighs 0.05 pounds, then the total weight of plastic containers is 500 pounds. If scale  136  records the weight in container  130  as being approximately 560 pounds, the purity measurement can then be calculated, according to the above formula, as X=(500 pounds)/(560 pounds)=0.89 (and 11% contaminants). 
     Unlike plastic containers, glass bottles often break during a sort process, resulting in untagged broken glass pieces being received at step  610 , as well as tagged pieces that have less weight than what the tags indicate. However, by statistical approximation, the total weight of the glass pieces can be calculated by summing the weight of the original unbroken bottles. Therefore, the weight percent may be calculated as described above. 
     The sort criterion of step  612  may also be set to a type of items  132   a ,  132   b  that do not have RFID tags affixed thereon. For example, waste items received in step  610  may include mostly of paper products that are untagged. If the number of untagged items  132   a ,  132   b  excluding the paper products is negligible, the total weight of the paper products can be calculated by subtracting the weight of items  132  from the total weight of items  132 ,  132   a ,  132   b  obtained in step  616 . The weight percent can then be calculated by dividing the total weight of the paper products by the total weight of items  132 ,  132   a ,  132   b.    
     If at decision step  618  it is determined that the number of untagged items is negligible (e.g., if optical counter  402  in  FIG. 4  counted substantially the same number of items as counted by reader-counter  128  in  FIG. 1 ), then, at step  620 , software  122  can determine or approximate the purity of bale  140  in terms of the weight percentage of certain types of recyclable items without measuring the total weight of items  132 ,  132   a ,  132   b  as in step  616 . This is a consequence of the total weight of items  132 ,  132   a ,  132   b  being approximated by summing the calculated weight of each of items  132 . For example, software  122  may query repository  124  using identification information  202  obtained from each of RFID tags  134  to determine the weight of each of items  132 . The percentage weight can then be approximated by calculation by dividing the total weight of items  132  that meet the sort criterion by the total weight of all items  132 . 
     Other measurements of purity, such as the percentage of items  132  that meet the sort criterion of step  612 , may also be calculated. For example, after step  614 , software  122  can query repository  124  using identification information  202  obtained from each of RFID tags  134  to determine a material type for each of items  132  that has an RFID tag affixed thereon, and count the number of items  132  for a particular material type specified in the sort criterion. The percentage of items  132  that meet the sort criterion of step  612  can be calculated as follows:
 
 X=RFID   C1 /( RFID   C1   +RFID   C2 )
         where X is the percentage of items that meet the sort criterion;   RFID C1  is the number of items that meet the sort criterion; and   RFID C2  is the number of items that do not meet the sort criterion.       

     As an example, the sort criterion may be set as aluminum containers. Assuming that all (or substantially all) aluminum containers have tags  134  attached thereto, software  122  determines that 10,000 items meet the sort criterion. In step  614 , the total number of items  132 ,  132   a ,  132   b  is determined to be 10500 (i.e., there are 500 other items, tagged or untagged). At step  620 , the percentage of items  132  that meet the sort criterion is therefore,
 
 X=RFID   C1 /( RFID   C1   +RFID   C2 )
 
X=10,000/(10,000+500)
 
X=0.95 or 95% aluminum containers (and 5% other)
 
     At step  624 , the purity measurement can be stored in repository  124 . At step  626 , items  132 ,  132   a ,  132   b  in container  130  can be loaded into baler  138  and compressed into bale  140 . 
     At step  628 , computer  120  can retrieve data that represents the contents of bale  140  from repository  124  (e.g., the sort criterion, total weight, and/or the purity measurement calculated) and use tag programmer  126  to write this data to bale RFID tag  142 , which can be affixed to bale  140 . Computer  120  may further update MRF bale inventory information, so MRF personnel are informed or can access repository  124  to determine, for example, that a bale with certain purity has been added to the MRF bale inventory. 
     At step  630 , bale  140  with tag  142  affixed thereon can be loaded onto vehicle  110 . At step  632 , vehicle RFID reader  114  can read tag  142 , and onboard computer  112  can store the data obtained from tag  142 . 
     At step  634 , data read from RFID tags (e.g., tag  142 ) associated with bales (e.g., bale  140 ) that are loaded on vehicle  110  can be transferred from onboard computer  112  to computer  120  via communications link  116 . This data represents all bales loaded on vehicle  110 . Computer  120  may further update MRF inventory information (e.g., as illustrated in  FIG. 5 ), so MRF personnel can know exactly which bales remain in the MRF inventory. 
     Other embodiments, extensions, and modifications of the ideas presented above are comprehended and within the reach of one skilled in the art upon reviewing the present disclosure. Accordingly, the scope of the present invention in its various aspects should not be limited by the examples and embodiments presented above. The individual aspects of the present invention, and the entirety of the invention should be regarded so as to allow for modifications and future developments within the scope of the present disclosure. The present invention is limited only by the claims that follow.