UWEE Tech Report Series

Making Distorted Spheres for Psychophysical Experimentation


Blake Hannaford

Haptics, spheres, metal working, psychophysics


How well can people detect shape with their fingers? How accurately can they discriminate between two small shapes? To study this problem, the Biorobotics Lab will test people's ability to detect which of two spherical ball bearings is ``perfect" and which is out-of-round. To create test objects for this work, we need a method to produce out-of-round spheres. Starting with factory made ball bearings, this report describes procedures we have developed to grind, sand, and polish the balls into a deformed shape with deformations as low as 0.002 inches. Care is taken to make sure surface texture is removed as a clue.

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