ActiveBat:1

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Active Bat A 3D Location Device

• http//www.uk.research.att.com/bat/
• -- presented by Yu-Chee Tseng --

2
Goal

• Low-power
• wireless
• inexpensive
• fine-grain 3D positioning sensor

3
Theory

• medium ultrasonic
• method triangulation
• an emitter is attached to an object
• receivers are mounted on the wall
• we measure the times-of-flight of the pulse to
  the receivers
• the speed of sound is known
• given 3 or more distances, we can determine the
  3D location of the object
• by keeping track of the 3D locations, we can
  determine the orientation and speed of the object

4
Hardware

• prototype of ultrasonic transmitter
• 5.5cm x 3cm x 2.4cm
• 30 g
• 3-month life time
• a unique 16-bit address

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Receivers

• mounted on the wall
• each 1.2 m apart
• networked to a PC

6
Results

• accuracy 10 cm (in each of the 3 dimensions)
• can find 25 objects per second
• Watch demo active-bat.mpg (from ORL).

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Applications

• Sentient computing system
• ATT Lab, Cambridge.
• Personnel carry wireless devices Bats.
• Sensors locates on the ceiling.
• Functions
• Spatial monitor (for browsing on the Web)
• Follow-me systems
• Data creation, storage, and retrieval

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Applications
1. trigger 2. emit signals 3. positioning by TOA
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Applications