Profile sensing with an actuated whisker

Obstacle avoidance and object identification are important tasks for robots in unstructured environments. This paper develops an actuated whisker that determines contacted object profiles using a hub load cell. The shape calculation algorithm numerically integrates the elastica equations from the measured hub angle, displacement, forces, and torque until the bending moment vanishes, indicating the contact point. Sweeping the whisker across the object generates a locus of contact points that can be used for object identification. Experimental results demonstrate the ability to identify and differentiate square and curved objects at various orientations.

I. Introduction

There are many robotic applications requiring obstacle avoidance and/or object identification in unstructured environments. The U.S. Navy, for example, is investigating the use of robotic underwater vehicles to accurately detect and classify underwater mines prior to beach landings in hostile territory. In the harsh and murky surfzone environment, delicate or optical sensors cannot be used. Limited communication bandwidth requires autonomous object detection and classification sensor systems. In this research, we use a rotary actuator to sweep a flexible wire whisker across an object and calculate contact-point locations, based on forces and torques measured by a hub load cell.