Designing an omnidirectional vision system for a goalkeeper robot

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Designing an omnidirectional vision system for a
goalkeeper robot

• E. Menegatti, F. Nori, E. Pagello,
• C. Pellizzari, D. Spagnoli

Dept. of Electronics and Informatics
The University of Padua Italy
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Presentations Outline

• The design of an omnidirectional mirror
• How the task commits the design
• Comparison b/t two mirrors designed for different
  tasks

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Related works

• Bonarini 1999
• Conical mirror with spherical vertex
• Hicks 1999
• Linear mirror
• Numerically solves differential equation
• Sorrenti 2000
• Multi-part mirror
• Isometric mirror
• Geometrically solves differential equation

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Mirror for a goalkeeper

• The task of the robot must determine
• the mirror profile

• The goalies tasks
• Self-localize
• Locate the ball
• Intercept the ball

• Requirements
• Good accuracy close to the robot
• Large field of view

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Different Mirror Profiles
Profile Pros Cons
Conical No body Const. Rel. Error Close is small Small FOV
Conical with Spherical Vertex Close is big Const. Rel. Error Body Small FOV
Isometric Const. Abs. error Preserve size Body Big Rel. Error
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The mirror we designed...

• Three parts
• Measurement Mirror
• Marker Mirror
• Proximity Mirror

Mirror Profile
The task determines the mirror profile
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How to design a mirror...
Mirror profile construction
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Simulations

• From the MatLab output to the PovRay Ray Tracer

Model of the Mirror
Simulated sequence
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Actual Mirror

• Picture of Lisas mirror

• Omnidirectional sequence

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Omnidirectional Software

• Calculating Ball Position

• Localisation using goalposts

• Goalkeeper Behaviour

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Calculating Ball Position

• Proportion b/t measurement mirror and proximity
  mirror

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Localisation using goalposts

• Find goalpost azimuth and distance
• Re-localisation is dangerous

Goalpost bottoms
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Goalkeeper Behaviour

• New goalkeeper moving
• Comparison with old moving

• Inactive ball
• Shot in goal
• Dangerous ball

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A Goalie's Mirror vs. An Attackers Mirror
Attacker
Goalkeeper
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Requirements

• For Goalie
• Locate the ball
• Identify the markers
• See the defended goal

• For Attacker
• Locate the ball
• Identify the markers
• See both goals
• Lighter mirror

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The attackers mirror

• Lighter
• Smaller
• Wider FOV

The new mirror

• Play on what you see, i.e.
• No absolute localisation in decision making!

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Two Mirrors, Two Tasks
Goalkeeper
Attacker
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Conclusion

• We showed how the task commits the mirror design
• We gave details on a mirror design procedure
• We gave practical hints on goalkeeper behaviour
• We highlighted the danger of a re-localisation
  process during a shot

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Acknowledgments

• We wish to thank
• A. Bonarini and D. Sorrenti
• The other members of the Artisti Veneti Team
  M. Barbon, M. Bert, C. Moroni, S. Zaffalon.
• This research has been supported by
• The Parallel Computing Project of the Italian
  Energy Agency (ENEA)
• The Special Project on Multi Robot Cooperative
  Systems of the University of Padua

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The Heterogeneous Team