Wall following control of a robotic fish using dynamic pressure

Abstract

This work controlled a robotic fish swimming alongside a wall. Research shows that fish swimming alongside a wall use lateral lines to obtain nearfield information. This concept is also applicable in man-made underwater vehicles such as robotic fish, which mimic the swimming action of a fish. Pressure sensors on the surface of a robotic fish measure hydrodynamic pressure variation. According to two-dimensional potential flow theory and the image method, the pressure variation caused by a robotic fish swimming near a wall is related to the relative angle and distance between the robot and the wall. Thus, the pressure signals can be used as feedback and inputs for controlling the direction in which the robot swims. The experimental results of this study show that a robotic fish 90 cm long can swim alongside a straight wall approximately 30–40 cm away (0.33–0.44 body length, 1–1.33 tail fin height). This method can also be combined with a well-designed strategy for using a robotic fish to swim next to an underwater structure to inspect details of structure parts.