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The aim of this project is to construct arrays of whisker-like sensors for the
acquisition of tactile information about objects in a robot's environment. These arrays
will be based on the structure and function of the rat whisker system.
Compared to e.g. infra-red sensors that are currently used in small mobile robots
for distance detection, the new whiskers have two major advantages:
- they report accurate distances to objects independent of the object's surface properties
- they work with the same precision under any lightening condition, from complete
darkness to bright sunlight.
A small inductive coil is attached close to the bottom of each whisker and is
activated by current pulses at a frequency of about 20Hz. A highly sensitive
magneto-resistive sensor detects the magnetic field. The strength and orientation
of the magnetic field provides information about the whisker's bending direction
and bending amplitude. Using consecutive pulses for nearby whiskers allows position
estimation of multiple whiskers without interference. A whisker's velocity and
acceleration can be estimated using the derivatives of multiple consecutive measurements.
We have successfully constructed a prototype of a sensory board containing a pair of
whiskers during the Telluride Workshop on Neuromorphic Engineering 2002. Currently
we are re-designing the board to provide a small modular system with eight whiskers,
that could eventually also serve as a touch-sensitive "skin" when surrounding the whole
robot. Ultimately, we hope to actuate the whiskers in a biologically inspired way.
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