A Whisker-inspired Fin Sensor for Multi-directional Airflow Sensing

This work presents the design, fabrication, and characterization of an airflow sensor inspired by the whiskers of animals. The body of the whisker was replaced with a fin structure in order to increase the air resistance. The fin was suspended by a micro-fabricated spring system at the bottom. A permanent magnet was attached beneath the spring, and the motion of fin was captured by a readily accessible and low- cost 3D magnetic sensor located below the magnet. The sensor system was modeled in terms of the dimension parameters of fin and the spring stiffness, which were optimized to improve the performance of the sensor. The system response was then characterized using a commercial wind tunnel and the results were used for sensor calibration. The sensor was integrated into a micro aerial vehicle (MAV) and demonstrated the capability of capturing the velocity of the MAV by sensing the relative airflow during flight.

I. INTRODUCTION

Whiskers achieve high-level interpretation on the mechanics of the whisker body by taking advantage of densely located sensory cells inside follicles [1]. When an external load is applied to a whisker, the forces and moments are transmitted through the whisker body resulting in the deformation of the follicle. This deformation is then converted to neural signals by mechanoreceptors [2]. The external load does not necessarily have to occur from contact, but it can also occur from fluid flow around the whisker. In fact, there are many examples of animals which exploit the flow sensing capability of their whiskers. Rats use whiskers not only to detect contact but to sense airflow during the whisking motion [3]. Seal whiskers are well-known for their water flow sensing ability [4]. Bats have whiskers (or hairs) located on their wings that are used to collect airflow information for feedback during flight [5]. These examples suggest that whiskers can be an efficient structure to sense airflow.