A bio-inspired robotic fish, which has flexible tail mechanism, can swim among its living counterparts quietly with lower consumption and higher maneuverability in water, where a conventional propeller AUV cannot reach. These kinds of robots are preferred for underwater exploration, observation andresearch purposes, especially where maneuverability is required. A group of engineering researchers from the University of Firat in Turkey are using biomimetic design and 3D printing to construct an intelligent robotic fish for real-world exploration and survey missions.
Important factors in the design of 3D printed biomimetic robotic fish are primarily the swimming modes and the body structure of the fish. In ichthyology, more than 85% of fish swim by bending their bodies and/or caudal fins (BCF) and about 15% of fish swim by median and/or pectoral fins (MPF). These biological properties indicate that BCF type Carangiform robot model is an appropriate approach for AUV design.
"There are two basic approaches in robotic fish design," the researchers wrote. "First is the biomimetic design which has certain requirements such as a tail with the size and number of joints to provide body travelling wave, and the ability to stay at a certain depth with the control of the center of gravity. The second design approach uses only the movement effects of fish, but it is not physically inspired by real fish."
The robotic fish prototype is approximately 500 mm long, 76 mm wide and 215 mm high. The prototype mass is also approximately 3.1 kg.
"The robotic fish prototype for three-dimensional motion abilities is investigated in the real experimental system. In these analyses, more than 72 different experimental studies were performed to obtain the characteristics of the prototype," the researchers explained. "In order to test the sealing performance of the mounted parts, they run during 6 hours in a water-filled test pool. The success of sealing tests is observed."
In the future work, the closed loop control performances of the prototype will be examined with different control structures, and swimming performance of the robot will be tested in different watercourses.
This robotic fish design provides versatile solutions for various different marine applications, such as examination of underwater resources, determination of pollution, observation of living forms, survey of submerged areas, fault detection in electricity or oil pipelines, coastline security and military missions.