Abstract
Autonomous small fish robots are ideal for surveys of fish resources and underwater structural inspections where electric wires hinder the movement of the robot or where radio signals, such as GPS, cannot be received. For practical usage such as taking pictures of fishes in the sea, the fish robot needs to follow the target fish and estimate its self-position to swim autonomously in water. The authors have developed a small fish robot named FPGA Offline Control Underwater Searcher (FOCUS) which has some micro CMOS cameras and an FPGA circuit board for data processing. Red objects can be detected with the CMOS camera. Using visual information from images taken from the bottom facing camera, self-position estimation becomes possible. The self-position estimation has been tested utilizing a real-time digital image correlation method using an FPGA. Development of a VHDL program for the FPGA and the mounting of FPGA on a circuit board have been conducted for target following and self-position estimation. This FPGA board executes both the control of the swimming fish robot and image processing at the same time. Results confirm that the small fish robot can follow the target and can measure simultaneously its self-position.
