Three-dimensional contact imaging with an actuated whisker

Contact sensors can provide high information density object surface sensing in harsh and/or opaque environments. This paper describes the design, modeling, control, and data processing of a contact imager consisting of a flexible whisker mounted on a two-axis robot through a load cell. The whisker sweeps around and into contact with unknown objects, determining the 3-D location of contact points to within a specified position resolution. During contact, the whisker bends along the surface normal, producing large deflections. The joint angles and load cell signals are numerically processed using an elastica model to determine the whisker shapes. Comparison of whisker shapes during bending determines contact point location. Experimental results for several objects with wide ranging surface curvature and roughness demonstrate 1.51 cm RMS resolution for a 45.5 cm whisker.