Extracting Object Contours with the Sweep of a Robotic Whisker Using Torque Information

Abstract

Several recent studies have investigated the problem of object feature extraction with artificial whiskers. Many of these studies have used an approach in which the whisker is rotated against the object through a small angle. Each small-angle “tap” of the whisker provides information about the radial distance between the base of the whisker and the object. By tapping at various points on the object, a full representation of the surface can be gradually constructed in three-dimensional space. It is clear, however, that this tapping method does not exploit useful information about object contours that could be extracted by “sweeping” the whisker against the object. Rotating the whisker against the object through a large angle permits the collection of a sequence of contact points as the whisker slips along the surface. The present paper derives an algorithm based on a numerical cantilever beam model of the whisker to measure object profile shape over a single large-angle whisker rotation using only information about torque and angle at the whisker base. The algorithm is validated experimentally using three different object shapes. As the method does not require measurement of force, it is well suited for implementation on an array of robotic whiskers to accomplish quick and precise object feature extraction.