Tactile tomographic fluid-flow imaging with a robotic whisker array

Current sensory array systems do not fully exploit tactile sensing strategies widely used by vibrissal sensing animals to explore their surroundings. We develop a new tactile fluid-flow imaging technique, which relates rat's whisker movements to tomographic imaging to extract fluid-flow characteristics with a robotic whisker array. At high Reynolds numbers, the drag force on a whisker segment is proportional to the relative velocity squared, and acts as a distributed load along the whisker length. Therefore, we propose that it is possible to map out the 2-D cross-sectional mean fluid-flow velocity field with a robotic whisker array by measuring the moment sensed at each whisker base from different directions for tomographic reconstruction. The associated inverse problem for the tomographic image formation is formulated as a MAP estimation problem and solved computationally. The experimental results demonstrate that this new approach offers a fundamentally novel sensor technology for flow-field measurements.