Variably spaced multi-point rfid tag reader systems and methods

Abstract

Systems and methods for determining a time of a passing at a reference line of an RFID tag traveling along a route and a time of lapsing of the tracked RFID tag on the route, the system have a plurality of spaced apart tag reader systems for wirelessly obtaining tag reads, wherein at least one of the tag reader systems is space apart from the reference line. The timing system receives a plurality of tag reads and determines the time of passing of the RFID at the reference line responsive to the plurality of received tag read messages received from the plurality of tag reader systems.

1 - 20 . (canceled) 
     
     
         21 . A system for determining a time of a passing at a timing point reference position of an RFID tag traveling along a route, the system comprising:
 a plurality of RFID tag reader systems each having a processor, a memory, a clock, a communication interface, and a corresponding radio frequency transceiver configured for positioning at a different, spaced-apart monitoring point relative to the timing point reference position and for wirelessly communicating with the RFID tag, and each having one or more antennas coupled to the corresponding radio frequency transceiver configured for positioning at an offset distance relative to each other along the route from the timing point reference position, the RFID tag reader systems each configured for transmitting via the one or more antennas tag read requests and receiving, via the one or more antennas at different positions along the route, one or more tag reads from the RFID tag; and   a timing system configured for storing in a timing system memory a tag reader normalization parameter associated with the timing point reference position and further configured for determining a time of passing of the RFID tag at the timing point reference position responsive to the received tag reads and the stored tag reader normalization parameter.   
     
     
         22 . The system of  claim 21  wherein a first one or more antennas are configured for positioning at a first offset distance along the route from the timing point reference position, and wherein a second one or more antennas are configured for positioning at a second offset distance along the route from the timing point reference position. 
     
     
         23 . The system of  claim 22  wherein the first offset distance is zero and a first monitoring position is coincidental with the timing point reference position and the second offset distance is not zero. 
     
     
         24 . The system of  claim 22  wherein neither the first nor second offset distances are zero and neither first nor second monitoring positions are coincidental with the timing point reference position. 
     
     
         25 . The system of  claim 21  wherein the timing system is configured for computing an average delta time for each of the received one or more tag reads and wherein the timing system is configured for determining the time of passing of the RFID tag at the timing point reference position responsive to the computed average delta times. 
     
     
         26 . The system of  claim 25  wherein at least one of the RFID tag reader systems transmits a plurality of tag reads, and wherein each average delta time is computed on each of the plurality of tag reads from different RFID tag reader systems. 
     
     
         27 . The system of  claim 21  wherein the RFID tag is a passive RFID tag and wherein each of the radio frequency transceivers of the RFID tag reader systems is configured to transmit a powering activation message and the read request message to the RFID tag and wherein the tag read requests are continuously transmitted as pulses. 
     
     
         28 . The system of  claim 21  wherein each tag read includes a data packet having a tag reader system identifier, a tag read time, and a tag serial number, wherein the timing system determines the time of passing of the RFID tag at the timing point reference position in response to the tag read times. 
     
     
         29 . The system of  claim 21  wherein each tag read includes a data packet having a tag reader system identifier, and a tag serial number. 
     
     
         30 . The system of  claim 21  wherein at least one of the tag reader systems includes a plurality of antennas and wherein each tag read includes a data packet having an antenna identifier that is unique to each antenna of the plurality of antennas and wherein the timing system determines the time of passing of the RFID tag at the timing point reference position responsive to the antenna identifiers received with two or more of the tag reads. 
     
     
         31 . The system of  claim 30  wherein each of the plurality of antenna are spaced apart from one another, and wherein a location of each of the plurality of antennas relative to the monitoring point at which the tag reader is located is configured to be stored in the timing system memory, and wherein the time of passing is determined as a function of a comparison of the stored location for the plurality of antennas from which the tag reads are received. 
     
     
         32 . The system of  claim 21  wherein each of the RFID tag readers is configured to receive a plurality of the tag reads from the RFID tag, and wherein each is configured to transmit its tag read to include a selected one of the plurality of one or more tag reads. 
     
     
         33 . The system of  claim 32  wherein the selected one of the plurality of one or more tag reads is a last such tag read received via the one or more antennas. 
     
     
         34 . The system of  claim 21  wherein the timing system is configured for determining the time of passing at the timing point reference position by performing the steps of:
 recording the time stamp by a first tag reader that is a time at a start of a monitored zone transition elapsed time; and 
 recording a time stamp by a second RFID tag reader that is a time at an end of the monitored zone transition elapsed time; 
 
       the method of the timing system comprising:
 computing the monitored zone transition elapsed time for the RFID tag traveling between first and second monitoring positions as the difference between determined time of passing of a second monitored point and determined time of passing of a first monitored point; and 
 determining the tag reader normalization parameter as a function of the computed monitored zone transition elapsed time. 
 
     
     
         35 . A method for determining a time of a passing at a timing point reference position of an RFID tag traveling along a route, said method comprising:
 wirelessly communicating with the RFID tag via one or more first antennas coupled to a first radio frequency transceiver of a first RFID tag reader system configured for positioning at a first monitoring position relative to the timing point reference position,   transmitting, by the first RFID tag reader system via the one or more first antennas, first tag read requests and receiving, by the first RFID tag reader system via the one or more first antennas, one or more first tag reads from the RFID tag,   wirelessly communicating with the RFID tag via one or more second antennas coupled to at least a second radio frequency transceiver of at least a second RFID tag reader system configured for positioning at a second monitoring position relative to the timing point reference position and spaced apart from the first monitoring position,   transmitting, by the second RFID tag reader system via the one or more second antennas, second tag read requests and receiving, by the second RFID tag reader system via the one or more second antennas, one or more second tag reads from the RFID tag, the one or more second antennas positioned at an offset distance along the route from the timing point reference position,   storing in a timing system memory a tag reader normalization parameter associated with the timing point reference position, and   determining a time of passing of the RFID tag at the timing point reference position responsive to the received first and second tag reads and the stored tag reader normalization parameter.   
     
     
         36 . The method of  claim 35  comprising:
 identifying each antenna having received each of the one or more first tag reads and the one or more second tag reads, 
 generating a tag read message to include an antenna identifier for each identified antenna, and 
 computing an average delta time for each tag read as a function of the antenna identifier. 
 
     
     
         37 . The method of  claim 36 , wherein each of a plurality of antennas of the one or more first antennas and the one or more second antennas are spaced apart from one another, the method including storing a location of each of the plurality of antennas relative to a monitoring point at which a tag reader is located, and wherein the determining of the time of passing is a function of a comparison of the stored location for two or more antennas from which the tag read messages are received. 
     
     
         38 . The method of  claim 36 , further comprising determining a position of the RFID tag relative to the first and second monitoring positions and wherein determining the time of passing of the RFID tag at the timing point reference position includes associating the determined position of the RFID tag relative to the first and second monitoring positions. 
     
     
         39 . The method of  claim 35  wherein determining the time of passing of the RFID tag at the timing point reference position includes identifying a position of the timing point reference position relative to both the first and second monitoring positions. 
     
     
         40 . The method of  claim 35  wherein recording a time stamp as a time at a start of a monitored one transition elapsed time and recording a time stamp as a time at an end of the monitored one transition elapsed time, the method of the timing system further includes computing a monitored zone transition elapsed time for the RFID tag traveling between the first and second monitoring positions both within proximity for detecting the time of passing by the timing point reference position as the difference between determined time of passing of the second monitoring position and determined time of passing of the first monitoring position.