Using a bioinspired robotic-fish for closed-loop control of zebrafish response in a preference test

This paper studies the response of zebrafish to a bioinspired robotic-fish. The robot's color pattern and morphophysiology are modulated to emphasize features normally admired by zebrafish in conspecifics. A three-chambered instrumented tank is utilized to conduct a series of preference tests, offering the robotic-fish as a stimulus, juxtaposed with an empty compartment, to live zebrafish. The time spent by fish in the proximity of either stimulus compartment is used to score the preference of an individual to a stimulus. The tail-beating motion of the robotic fish is manipulated based on closed-and open-loop control strategies. The closed-loop controller uses the distance of the live-fish from the robotic-stimulus as its control input, while the open-loop controller provides a tail-beating motion, irrespective of fish behavior. Live-fish locomotion patterns and their preference space are compared and analyzed to ascertain the effects of closed-loop control on zebrafish response. This study's results suggest that closed-loop control reinforces attraction to the robotic-stimulus, as compared to the open-loop approach, over extended exposure to the robot, therefore aiding against habituation to a stimulus.