A European academic consortium is to build a robot fish that can swim predictably in moving and turbulent water.
Key to the robot are micromachined flow sensors that detect the local hydrodynamic environment - mimicking the 'lateral line' found in real fish.
"We want to build something simple in its mechanical design, and give it an artificial lateral line to give it a sense of what is going on in the water around it," Dr William Megill of the University of Bath told Electronics Weekly.
The three year project called Filose (robotic fish locomotion and sensing), has two phases:
"We need to understand what the information we get from the sensors means, then we need to use this to improve propulsive effect," said Megill.
The outcome should be a machine between the size of a trout and a salmon that includes sensors, intelligence and actuators, but will be powered through an umbilical.
"The robot could be used near the seashore, where conventional propeller-driven submersible robots have difficulty manoeuvring due to the shallow water, kelp, and currents created by waves," said the University of Bath.
The University of Essex has been making robot fish for several years, including a famous one that swam in the London Aquarium link
"The Essex fish is a gorgeous piece of engineering with some really nice control in it," said Megill, explaining: "Theirs is a way of testing artificial intelligence, ours is a way of finding out why it is that a fish is so much better at moving around in its environment than a machine."
Mechanically, the Essex fish is a segmented design with vertical hinges, each powered by a servo.
The Filose fish will be simpler, with one or two actuators at the front and a flexible, springy, rear section.
According to Megill, this is similar to the way both fish and dolphins work.
"A dolphin has four muscle groups that act as two: one on the top and one on the bottom, that drive an elastic tail as a way to transmit force to the water," he said. "Fish have muscles at the front that make a swim-wave, which is transmitted back by muscles which only modify it slightly, they act more like tendons."
The exact mechanical form has yet to be decided.
It looks like either one servo or two solenoids will initiate the swim-wave at the front, with a piece of silicone rubber acting as the elastic rear section.
"The rubber will be very special, to transmit the wave elastically along its length," said Megill.
Its stiffness will have to be controlled, with current options including either: active pneumatic or hydraulic compressive elements, or a passive springy 'spine' with two different stiffnesses (an oval beam for example) that is rotated through 90 degrees to select a stiffness.
Bath's contribution to the consortium is biological, Megill and the Ocean Technologies Lab are studying real trout for the project.
Lead institute Tallinn University of Technology in Estonia, together with Riga Technical University in Latvia, will design the robot and its propulsion system.
Researchers at the Italian Institute of Technology (IIT) in Lecce will be developing the micromachined flow sensor.
The fish's nervous system will be emulated by computer software developed by the University of Verona, which will allow the robot to interpret changes in flow outside the robot so it can adjust its swimming behaviour to compensate.
A second team from the IIT, based in Genoa, will be designing the computer hardware and electronics to interpret the lateral line information and generally control the robot.
FILOSE has been granted E1.8m through the EU 7th Framework Program
http://www.bath.ac.uk