Wheeled vehicle mounted with RFID tag, RFID tag, speed measurement system, and speed measurement method

A wheeled vehicle comprising:

• an RFID tag comprising a memory portion, a battery that can be charged, and a charge control circuit,
• wherein the memory portion holds identification information on a wheeled vehicle,
• wherein the charge control circuit examines whether or not a voltage of the battery reaches a given value, and charges the battery in a case where the RFID tag receives a signal from a interrogator, and
• wherein the RFID tag sends the identification information on a wheeled vehicle to a interrogator in a case of receiving a signal form the interrogator.

An RFID tag comprising:

• a memory portion;
• a battery that can be charged;
• and
• a charge control circuit,
• wherein the memory portion holds identification information on a wheeled vehicle,
• wherein the charge control circuit examines whether or not a voltage of the battery reaches a given value, and charges the battery in a case where the RFID tag receives a signal from a interrogator, and
• wherein the RFID tag sends the identification information on a wheeled vehicle to a interrogator in a case of receiving a signal from the interrogator.

A speed measurement system comprising:

• a first interrogator which detect first identification information on an RFID tag set on a wheeled vehicle;
• a second interrogator which detect second identification information on the RFID tag set on the wheeled vehicle;
• a computer that is connected to the first interrogator and the second interrogator,
• wherein the second interrogator is placed to have a given distance from the first interrogator,
• wherein the second interrogator detects the second identification information, after the first interrogator detects first identification information, and
• wherein the computer holds first timing information on date and time in detecting the first identification information,
• wherein the computer holds second timing information on date and time in detecting the second identification information,
• wherein the computer calculates average speed of the wheeled vehicle between the first interrogator and the second interrogator, by the first timing information, the second timing information and the given distance.

A method for measuring speed comprising the steps of:

• placing a first interrogator which detect first identification information on an RFID tag set on a wheeled vehicle;
• placing a second interrogator which detect second identification information on the RFID tag set on the wheeled vehicle, wherein the second interrogator is placed to have a given distance from the first interrogator;
• measuring first timing information on date and time in detecting the first identification information;
• measuring second timing information on date and time in detecting the second identification information;
• and
• calculating first average speed of the wheeled vehicle, by the first timing information, the second timing information and the given distance.