Summary

Underwater mines fortify many beachheads and can cause significant damage to an assault force.  The ability to secretly detect, classify, and map the locations of underwater mines prior to the landing of an assault force is of considerable importance.

This project develops an active whisker sensor for autonomous mine-hunting vehicles in the surfzone that determines contacted object shapes 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.  

Collaborator

Charles Bernstein, US Navy, Coastal Systems Station

Sponsor

Office of Naval Research

Whisker sweep past a concrete block: (a) t = 5 sec; (b) t = 6 sec; (c) t = 7 sec. The figure shows the progression (top to bottom) of a whisker sweep past a rectangular object. The superelastic Nitinol whisker is torqued by a Maxon brushed DC motor.  The hub motor is controlled via PID encoder feedback to follow a sinusoidal trajectory despite the disturbance torques from object contact.  All hub forces and torques pass through a six axis ATI Mini 40 load cell.

Experimentally predicted whisker shapes and contact points for a square object (superimposed in gray) at different orientations.  A MATLAB program generates the whisker shapes for a sweep past an object.  The shapes for several sweeps are then plotted on the same graph, revealing the shape of the object. 

For further information:  cdrahn@psu.edu. 

Copyright © 2001 Mechatronics Research Laboratory