Patent ID: 7764176

Claim:
A method for confirming entry and/or exit state of a mobile object relative to an entrance of an underground passageway by utilizing Radio Frequency Identification (RFID) technology, wherein at least one RFID tag is physically attached to the mobile object and at least a first RFID reader and a second RFD reader, each having a monitoring range and being in communication with the RFID tag, are disposed at the entrance and an relatively inner position of the passageway respectively, said method comprising the steps of: generating a first entering-state data if the RFID tag enters the monitoring range of the first RFID reader and a first exiting-state data if the RFID tag exists the monitoring range of the first RFID reader; generating a second entering-state data if the RFID tag enters the monitoring range of the second RFID reader and a second exiting-state data if the RFID tag exits the monitoring range of the second RFID reader; and processing the first entering-state and exiting-state date and the second entering-state and exiting-state data to generate an output data indicating the entry and/or exit state of the mobile object relative to the entrance of the passageway, wherein; generating a first entering-state data and a first exiting-state data comprises generating a first entering time if the RFID tag enters the monitoring range of the first RFID reader and generating a first exiting time if the RFID tag exits the monitoring range of the first RFID reader; and generating a second entering-state data and a second exiting-state data comprises generating a second entering time if the RFID tag enters the monitoring range of the second RFID reader and generating a second exiting time if the RFID tag exits the monitoring range of the second RFID reader.