We can work in environments that are very weedy, and would usually snag up propellers

Dr Ian Dukes, University of Essex

In the shallow waters of Gijon harbour, in northern Spain, a large, yellow fish cuts through the waves.But this swimmer stands apart from the marine life that usually inhabits this port: there's no flesh and blood here, just carbon fibre and metal.This is robo-fish - scientists' latest weapon in the war against pollution.This sea-faring machine works autonomously to hunt down contamination in the water, feeding this information back to the shore.

The Shoal consortium is formed of the BMT Group, the University of Essex, the Tyndall National Institute, the University of Strathclyde, Thales Safare and the Port Authority of Gijon.

We want the fish to have the ability to look for its own charging station, just like a real fish looking for food

Prof Huosheng Hu, University of Essex

"It actually has a computer embedded inside, and also have a number of sensors. For example they have infrared sensors in the front to detect obstacles. They have gyroscope to actually try to maintain the attitude of the fish. They also have pressure sensors to actually detect how ... What's the level in the water. Other applications include sea bed exploration for resources, or for rescue jobs, and also for the underwater oil pipe leaking detection, and also telecommunications cable detection as well. I think the bigger challenge for us now, how to make the public understand the robots is close to them and actually is their friend and their assistant in the coming 10 years or 20 years time." "We have embedded sensors on board - so, unlike the previous fishes that have remote controls, these are fully autonomous and artificial-intelligence based," lead researcher Professor Huosheng Hu, told the BBC News website.

The goal of the researchers of the university of Essex was to carry out a robot-fish which can swim like a real fish and which is autonomous. A fish has various modes of displacement (speed, turns, accelerations, braking) and the challenge of the researchers of Essex was to obtain an autonomous robot-fish who can reproduce all these behaviors and not one or two in a more or less uniform way. They thus indexed the various behaviors in a library used by the computer to generate varied and unexpected trajectories of stroke. Robotic Fish (50 cm length) is for example able to curve its body according to a great angle in a very reduced time (approximately 90°/0.20sec). Several models were designed, since G1 in 2003 until G8 and G9 in 2005. The researchers continue to work on the improvement of the algorithms of training which make it possible the robot to generate adaptive behaviors in a changing environment and thus unpredictable.