A tactile stress rate sensor for perception of fine surface features

The author reports the development of a new type of contact sensor for the measurement of fine surface features and textures down to the micron level. The sensor has a complicated rubber covering and is inexpensive and robust. As it is stroked across the surface of interest, piezoelectric transducers embedded in the sensor surface respond to stress induced by surface features. The sensor uses a current amplifier in place of the traditional charge amplifier, which eliminates many of the problems associated with piezoelectric transducers. The resulting signal is proportional to the rate of change of stress, or the stress rate. The signal can be interpreted with the aid of a solid mechanics model of the contact interaction and a linear deconvolution filter. The ability to detect features as small as a few micrometers has been experimentally confirmed. Intended applications include perception of surface properties to improve the robustness of robotic manipulation and rapid evaluation of surface finish in manufacturing.<>