Crayfish Robot Equipped with Active Flow Generator to Enhance Chemical Reception

This paper describes an underwater wheeled robot designed to search for a chemical source under stagnant flow conditions. In the absence of the flow, the released chemical stays in the immediate vicinity of the source. Therefore, no chemical is detected even if the robot is only a few centimeters away from the source. Crayfish in search for food are known to actively generate water currents using their maxillipeds, i.e., the fanning appendages. The generated flow field draws odor samples from distant places to the chemoreceptors. The proposed robot generates water currents by waving small arms that mimic the crayfish maxillipeds. Electrochemical sensors with four carbon working electrodes detect the collected chemical substance. Depending on the direction of the chemical source, the patch of a chemical substance was drawn to a different sensor. Experimental results are presented to show that the flow field generated by waving maxilliped-like arms is more effective in enhancing chemical reception than that generated by a pump. The proposed crayfish robot can localize a chemical source with high success rate if the source is placed within the range in which the generated water currents can draw chemical substance to the sensors.