Fisho: A cost-effective intelligent autonomous robot fish

We developed a cost-effective fish-like Autonomous Underwater Vehicle (AUV) with a sophisticated intelligence. The robot fish, named Fisho, is able to avoid obstacles in a swimming pool, reflecting the usual behavior of a biological fish. As a general rule, a robot captures external stimulus by means of electrical sensors; Fisho has infrared sensors to find the distance to close objects and pressure sensors to estimate its vertical physical position (depth). Its brain is a small-sized 200-MHz Single Board Computer (SBC), that collects information from the sensors and sends decisions to electro-mechanical servos (in order to act on its tail and flippers, thus control its trajectory). Fisho´s behavior is signed by its velocity and the vibration mode of its tail. Inspired in real fish, we designed its intelligence with a three-layer Markov chain by means of a full characterization of tasks, purposes and fish-moods. Its design and physical structure is both non-expensive and simple, trying to emulate a real fish, whereas addressing all typical challenges in an AUV. In this paper we discuss Fisho´s physical implementation: sensing platforms, electro-mechanical structure and intelligence.