26 research outputs found
Tactile Superresolution and Biomimetic Hyperacuity
Motivated by the impact of superresolution methods for imaging, we undertake a detailed and systematic analysis of localization acuity for a biomimetic fingertip and a flat region of tactile skin. We identify three key factors underlying superresolution that enable the perceptual acuity to surpass the sensor resolution: 1) the sensor is constructed with multiple overlapping, broad but sensitive receptive fields; 2) the tactile perception method interpolates between receptors (taxels) to attain subtaxel acuity; and 3) active perception ensures robustness to unknown initial contact location. All factors follow from active Bayesian perception applied to biomimetic tactile sensors with an elastomeric covering that spreads the contact over multiple taxels. In consequence, we attain extreme superresolution with a 35-fold improvement of localization acuity (0.12 mm) over sensor resolution (4 mm). We envisage that these principles will enable cheap high-acuity tactile sensors that are highly customizable to suit their robotic use. Practical applications encompass any scenario where an end-effector must be placed accurately via the sense of touch
Artificial SA-I and RA-I Afferents for Tactile Sensing of Ridges and Gratings
For robot touch to converge with the human sense of touch, artificial
transduction should involve biologically-plausible population codes analogous
to those of natural afferents. Using a biomimetic tactile sensor with
3d-printed skin based on the dermal-epidermal boundary, we propose two novel
feature sets to mimic slowly-adapting and rapidly-adapting type-I tactile
mechanoreceptor function. Their plausibility is tested with three classic
experiments from the study of natural touch: impingement on a flat plate to
probe adaptation and spatial modulation; stimulation by spatially-complex
ridged stimuli to probe single afferent responses; and perception of grating
orientation to probe the population response. Our results show a match between
artificial and natural afferent responses in their sensitivity to edges and
gaps; likewise, the human and robot psychometric functions match for grating
orientation. These findings could benefit robot manipulation, prosthetics and
the neurophysiology of touch