Patent ID: 7363125
Filing Date: 2008-04-22
Classification: G01S

Abstract:
1. A tracking system comprising a transponder attached on a moving object, and an autonomous mobile unit for tracking the transponder: the autonomous mobile unit having a first ultrasonic transceiver device and an environment detecting means for acquiring reflection environment information relating to a wall surface existing around the autonomous mobile unit and the transponder, and the transponder having a second ultrasonic transceiver device, wherein: (i) the autonomous mobile unit transmits a first ultrasonic wave from the first ultrasonic transceiver device; (ii) the transponder receives the first ultrasonic wave at the second ultrasonic transceiver device and thereafter, triggered by reception of the first ultrasonic wave, transmits a second ultrasonic wave from the second ultrasonic transceiver device; (iii) the autonomous mobile unit acquires, by receiving the second ultrasonic wave at the first ultrasonic transceiver device, reception information relating to a direct wave that directly arrives at the first ultrasonic transceiver device from the second ultrasonic transceiver device, and relating to a reflected wave that arrives at the first ultrasonic transceiver device from the second ultrasonic transceiver device by being reflected by the wall surface; and (iv) the autonomous mobile unit makes a decision whether the received second ultrasonic wave is the direct wave or the reflected wave using the reception information and the reflection environment information, and estimates a position of the transponder by processing the reception information based on the decision, to track the transponder.