Part Feeding by Potential Fields

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Part Feeding byPotential Fields

• Attawith Sudsang andLydia E Kavraki
• Presented by Petter Frykman

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Part Feeding, history

• Generally used devices
• Vibratory bowlsPlacing the part in a specially
  designed bowl and let the vibrations orient the
  part. The bowl has to be redesigned for each
  part.
• Trap doorsSome kind of bowl with a special shape
  and a special shaped hole in the bottom. Also has
  to be redesigned for each part.

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Part Feeding, now days

• Research topics
• Vibratory bowlsTrying to analyze the process of
  design.
• Programmable part feedersBuild more robust and
  general feeders that can be reprogrammed to be
  able to feed a new part. In micro scale by using
  MEMS actuators and in macro scale by using
  mechanical devices such as jet air thrusters or
  vibrating plates. (Also first papers parallel
  jaws.)

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Potential Field

• A force field that applies a force to every point
  on the part, that is towards a special center
  point and has magnitude equal to a constant times
  the distance to the center point. This force
  field is the same as a potential quadratic bowl.

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Potential Fields

• MEMS actuators and air thrustersThese devices
  can be seen as programmable force fields or
  potential fields. The underlying idea is that a
  part that is lying in such field is driven
  towards a stable equilibrium by the resulting
  force and torque induced by the field, or to a
  potential local minimum for the part.
• Squeeze fieldsBy applying a sequence of squeeze
  fields to the part we can orient a polygonal part
  in a similar way as the first papers parallel
  jaws.

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Potential Fields

• Elliptical force fieldThis field applies a force
  to each point of the part such that all points
  that is on the same elliptical contour will have
  the same magnitude of force. This field induces
  two stable equilibria.
• Unit radial and small constant force fieldsThe
  unit radial force field is a point p0 and every
  point p of the part will experience a force
  towards p0 that is equal in magnitude to the
  distance between p and p0. The small constant
  field is just a constant force that all points
  experience the same way. This field induces just
  one stable equilibrium.

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Linear Radial Force Fields

• combined with constant force fieldThe linear
  radial force field is a radial field like the
  unit radial field but the magnitude of the force
  is a linear function of the distance from p to
  p0. The combination of these two is a field
  defined by the magnitude of the constant field
  and the coefficients defining the linear function
  associated with the radial force field. For a
  given part there is a set of parameters for the
  field such that the field induces one stable
  equilibrium for the part.

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How does that look?
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and the theory

• The constant field can be split into two radial
  fields

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Split the field into two parts
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Pivot Points
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Pivot Points
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Unique Stable Equilibrium