Radio Frequency Identification

1
Radio Frequency Identification

• Yang Gu

2
What is RFID?

• RFID is a generic term
• It use radio waves to automatically identify
  objects.
• the most common method is to store a serial
  number on a microchip that is attached to an
  antenna.

3
RFID System, Components
4
Components

• Transponder (tag)
• located on the object to be identified
• consists of a coupling element and an electronic
  microchip.
• Tags are available with storage capabilities from
  512 bytes to 4MB.
• Reader, contains
• a high frequency module
• a control unit and a coupling element to the
  transponder.

5
Tag options

• Passive tags
• draw power from the magnetic field generated
  between itself and a reader
• Active tags
• larger and more expensive
• self-powered by an internal battery  
• Can either provide active presence or active
  location information. 
• Active location RFID systems support a higher
  effective read range with greater resolution
  capabilities

6
The read range for a typical RFID tag

• It depends on many factors
• the frequency of operation,
• the size and shape of the tag,
• the power of the reader,
• interference from metal objects or other RF
  devices.
• In general,
• low-frequency passive tags are read from a foot
  or less. High frequency passive tags are read
  from about three feet
• UHF tags are read from 10 to 20 feet.
• semi-passive and active tags use batteries to
  boost read ranges to 300 feet or more.

7
How much do RFID tags costs?

• 30 cents - 50 depending on the type of tag and
  the application.
• Active tags those with a battery can cost far
  more.
• And if you bundle in a sophisticated sensor, the
  cost can rise to more than 100.

8
Next Step RFID and Intelligent Agent

• Most readers have additional interface (RS 232,
  RS 485, ...) to enable it to forward the data
  received to the segway robot.
• Information provided by RFID systems can be used
  as vision for automate decision-making processes

9
Is it suitable for Segway?

• Segway
• read range 24 feet
• Update frequency 25Hz (current vision)
• Not only object identification, but also a need
  to precisely locate objects in real-time.
• Distance precision

• RFID
• UHF/microwave tags
• n/a
• Using active tags for moving objects and passive
  or semi-passive tags for markers??
• Can be as precise as within a few centimeters
  (RTLS)
• cost??

10
Compare with vision

• Vision update rate 25 frames/sec, RFID n/a
  (best known update every few seconds) ??
• Position precision best known RFID can do much
  better than vision does. ??
• RFID can locate both relative and global position
  for the tagged objects on the field without
  looking at them!
• Easy setup for RFID, does not need color training
  or calibration.
• RFID is more expensive than using multiple
  web-cameras but save much more effort in software
  implementation.

11
Issues

• Update rate and distance precision
• Cost for a tracking system
• Interface (hardware/software)
• Orientation
• the reader cannot communicate effectively with a
  tag that is oriented perpendicular to the reader
  antenna.

12
Conclusion

• If the update rate and position precision
  satisfy, RFID is definitely a better choice to do
  soccer game. RFID will let us focus more on
  strategy based on a precise world model.
• ?