WhiskSight: A Reconfigurable, Vision-Based, Optical Whisker Sensing Array for Simultaneous Contact, Airflow, and Inertia Stimulus Detection

The development of whisker-based sensing systems faces at least two important technical challenges: scaling up the number of whiskers to large arrays while retaining a simple interface; and detecting the wide variety of stimuli that biological whiskers can sense, including both direct touch (contact) and airflow. Here we present the design for a whisker array that leverages a camera to measure whisker rotations without a complex interface. Whiskers are magnetically attached to an elastomer “skin,” ensuring that the system is both scalable and reconfigurable. Direct contact is measured from the relative motion between each whisker and the skin, while airflow and inertia can be inferred from the signal experienced by all whiskers in the array. Individual whiskers can resolve the direction of contact transverse to the whisker within ${6.2}^{\circ }$ and whisker rotation magnitude to within ${0.5}^{\circ }$. An algorithm is developed to distinguish inertial forces from airflow and contact.

I. Introduction

Whiskers, also known as vibrissae, are important tactile sensors for almost all mammals. Mammalian whiskers are arranged in bilateral arrays, with 25 or more whiskers emerging from each side of the animal's face [1]. Unlike insect antennae, which have mechanical and chemical sensors along their entire length, mammalian whiskers resemble hairs: sensing occurs only at the whisker base within a densely-innervated follicle [2]. Animals use their whiskers to help with rapid motion planning and navigation, to localize contact with objects, to distinguish object size, shape, texture, and orientation, and to sense fluid flow. Moreover, whisker-based sensing can distinguish between stimuli that occur simultaneously (e.g., contact can be distinguished from the inertial forces generated by the animal's own motion).