Wireless tracking system and method with optical tag removal detection

• US 7,336,182 B1
• Filed: 10/19/2007
• Issued: 02/26/2008
• Est. Priority Date: 10/19/2007
• Status: Active Grant

• Current Assignee: Centrak Incorporated (Halma PLC)
• Original Assignee: Awarepoint Corporation
• Inventors: Caliri, Dyami, Smith, Derek, Baranowski, Robert
• Primary Examiner(s): NGUYEN, PHUNG
• Application Number:
  US11/875,796
• Time in Patent Office: 130 Days
• Field of Search: 3405721-5729, 340/506, 340/539.15, 340/539.13, 340/539.23, 340/555, 340/568.1, 340/522, 250/200
• US Class Current: 340/572.1
• CPC Class Codes: G08B 13/1436 with motion detection
• CPC Class Codes: G08B 13/1481 with optical detection
• CPC Class Codes: G08B 13/2448 Tag with at least dual detection means, e.g. combined inductive and ferromagnetic tags, dual frequencies within a single technology, tampering detection or signalling means on the tag

Abstract

A wireless tracking system and method with a tag removal detection feature is disclosed herein. The system and method utilize a tag attached to an asset which includes a processor, a motion sensor (such as an accelerometer), a transceiver, a tag removal sensor and a power source having a limited supply of power. The tag removal sensor is an optical sensor which is activated only when the motion sensor detects motion. In this manner, the tag conserves power since the tag is typically only in motion ten percent of the day. If the tag is removed from the asset, the optical sensor confirms the removal and an alert is activated by the system.

Claims

1. A method for determining if a tag has been removed from an asset within an indoor facility, the method comprising:

tracking a location of an asset bearing a tag, the tag comprising a processor, a motion sensor, a transceiver, a tag removal sensor, a power source having a limited supply of electrical power;

detecting motion of the tag by the motion sensor and communicating the motion to the processor;

transmitting an activation signal from the processor to the tag removal sensor, the activation signal activating the tag removal sensor from a low power consumption state to an activation state, wherein the tag removal sensor is an optical sensor that emits light from the tag to the asset and receives the light reflected from a surface of the asset indicating that the tag is attached to the asset;

determining if the tag is currently attached to the asset;

transmitting an unattached signal from the tag removal sensor to the processor and from the processor to the transceiver to indicate that the tag is currently unattached to the asset;

broadcasting the unattached signal from the transceiver of the tag to a plurality of network sensors positioned within an indoor facility; and

transmitting the unattached signal from at least one of the plurality of network sensors to a positioning engine to generate a warning.