Where are you

1
University of WyomingDepartment of Computer
ScienceDistributed Robotics LaboratoryLaramie,
Wyoming, USA

• Where are you?
• Paul M. Maxim
• William M. Spears, Jerry C. Hamann, Thomas
  Kunkel,
• Rodney Heil, Dimitri V. Zarzhitsky, Diana F.
  Spears, Christer Karlsson

Project sponsored in part bythe Joint Robotics
Program and NSF
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Outline
Standalone Trilateration Module
Highly portable I2C based modular concept
Accurate without s/w noise filtering
Fast improved equations
Coupled with Communication
Allows asynchronous movement
Tackle a wide range of problems
3
Problem

• Ability for robots to interact with each other
• chemical/biological plume tracing,
• distributed sensing grids,
• obstacle avoidance,
• map generation,
• mine clearing.

Old UW-DRL Robot Design
4
Solution

• Swarm robot technology equipped with a
  localization system
• Use trilateration method for localization system

New UW-DRL Robot Design
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Trilateration

• Uses one RF transceiver and three acoustic
  transducers to determine relative position of
  other robots

Thunder and lightning
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Related work

• Robots serve as beacons
• Millibots
• Navarro-Serment et al. - 2002,
• Shapebugs
• Cheng et al. 2005
• Inline acoustic transducers MacArthur - 2003

Prior work does collaborative trilateration
Our localization system inexpensive, fast,
accurate, and self-contained.
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Outline
Standalone Trilateration Module
Highly portable I2C based modular concept
Accurate without s/w noise filtering
Fast improved equations
Coupled with Communication
Allows asynchronous movement
Tackle a wide range of problems
8
Trilateration methods
d
d
Equilateral triangle pattern
XY coordinate system pattern
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Equilateral triangle pattern
trilateration equations
our goal k 1
d
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XY coordinate system pattern
well-conditioned matrix
d
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Outline
Standalone Trilateration Module
Highly portable I2C based modular concept
Accurate without s/w noise filtering
Fast improved equations
Coupled with Communication
Allows asynchronous movement
Tackle a wide range of problems
12
Synchronization protocol

• every 300 ms one robot is transmitting
• additional sensor information is transmitted

Robot 3 receives
13
Outline
Standalone Trilateration Module
Highly portable I2C based modular concept
Accurate without s/w noise filtering
Fast improved equations
Coupled with Communication
Allows asynchronous movement
Tackle a wide range of problems
14
The Essence of Trilateration

• Recall - must be able to detect an RF pulse and
  three acoustic signals.

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Oscilloscope snapshot
RF arrival time
Sound arrival time
C
B
A
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Trilateration challenges

• High sensitivity
• (signal amplification signal filtering)
• High accuracy
• (requires hardware and software solution)
• Solution need to build new sonic range finder.

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Experimental XSRF schematic
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X Sonic Range Finder - XSRF
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Complete Trilateration Module

• Three XSRF sensor boards,
• Three ultrasonic transducers,
• Three parabolic cones,
• Wireless RF transceiver.

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Channelling acoustic energyinto a plane
Acoustic transducers and parabolic cones
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Trilateration module
A
C
B
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Previous Accuracy Resultsaverage error 4.8
inches (12.2 cm)
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Current Accuracy Resultsaverage error 0.6
inches (1.5 cm)
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The Maxelbot
Trilateration Module
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HCS12 Controls Trilat
Digital Compass
HCS12 Controls Robot
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Outline
Standalone Trilateration Module
Highly portable I2C based modular concept
Accurate without s/w noise filtering
Fast improved equations
Coupled with Communication
Allows asynchronous movement
Tackle a wide range of problems
28
Chemical Plume Tracing

• Objective Identify a chemical emission and trace
  the chemical plume to its source emitter.
• Requires at least two chemical sensors to find
  the chemical gradient.
• Significantly better results when use multiple
  collaborating robots.

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Experiments and demonstrations

• three Maxelbots pulling a box,gt
• three Maxelbots using AP to self organize and
  move towards a goal,gt
• three Maxelbots using AP to self-repair and move
  towards a goal,gt
• three Maxelbot CPT test run.gt

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Summary
Standalone Trilateration Module
Highly portable I2C based modular concept
Accurate without s/w noise filtering
Fast improved equations
Coupled with Communication
Allows asynchronous movement
Tackle a wide range of problems
31

• Questions