AsianScientist (Jun. 28, 2013) – Researchers from the National University of Singapore’s (NUS) Department of Electrical & Computer Engineering have developed a robot fish that mimics the movements of a carp.
The robot is an autonomous underwater vehicle (AUV) that can be programmed to perform specific functions such as underwater exploration in places that are difficult for divers or traditional AUVs to access. Other applications include military activities, pipeline leakage detection, and the laying of communication cable.
The research team comprises of Professor Xu Jianxin; Mr. Fan Lupeng, graduating Electrical Engineering student; and research fellow, Dr. Ren Qinyuan.
“Currently, robot fish capable of 2-D movements are common, meaning that these models are not able to dive into the water. Our model is capable of 3-D movements as it can dive and float, using its fins like a real fish. Compared to traditional AUVs, they are certainly more mobile, with greater maneuverability. If used for military purpose, fish robots would definitely be more difficult to detect by the enemy,” said Prof. Xu.
Fish robots are also quieter and consume less energy compared to traditional AUVs, said Mr. Fan. The team used a camera to capture all the possible movements of a carp, before converting the data mathematically to transfer the locomotion of real carp to the robot using different actuators, he explained.
Replicating the locomotion of real carp has been challenging, Dr. Ren said, as fish use a lot of different muscles to move, and many actuators are required to enable the robot to move in the same manner.
“Some fish can achieve almost 180 degree turning in a small turning radius through bending their body while traditional underwater vehicles have a much larger turning radius. Hence it is quite a feat for us to achieve this movement in our robot fish,” said Dr. Ren.
Other challenges included waterproofing the fish body, the motor, and the control box. The fins and tails also needed to be flexible and the team decided to use very fine (1 mm) acrylic board for these. Buoyancy and balance for the robot was maintained by using plastic foams attached to both sides, and the robot fish was equipped with an internal ballast system to allow it to dive to a precise depth.
The team has constructed two fish robots: the larger prototype is about one and half meters in length, weighing about 10 kg, with the ability to dive to a depth of 1.8 meters, and the smaller robot is about 60 centimeters long, weighing about 1.5 kg, but which can only swim at the water surface.
Underwater vehicles have long gone past the days of the submarines, said Mr. Fan, who hopes to make the robot carp even smaller and more realistic.
“We intend to equip it with more sensors like GPS and video camera to improve autonomous 3-D movement. We also intend to test out our fish with more challenging tasks such as object detection,” he said.
The research will be featured at the IEEE/RSJ International Conference on Intelligent Robots and Systems, taking place in Tokyo from November 3-7, 2013.
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Source: NUS.
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