- Title: SWITZERLAND-CUTTLEFISH ROBOT Sepios the robot cuttlefish takes to the sea
- Date: 16th February 2015
- Summary: ZURICH, SWITZERLAND (FEBRUARY 6, 2015) (REUTERS) (SOUNDBITE) (English) ALESSANDRO SCHAPPI, STUDENT AT ETH ZURICH AND CO-DESIGNER OF SEPIOS ROBOT CUTTLEFISH, SAYING: "We do have a camera and a laser and with the camera and the laser in here we are able to do collision detection, so that we don't swim into the walls. So if we detect the wall we just turn around and we swim i
- Embargoed: 3rd March 2015 12:00
- Keywords:
- Location: Switzerland
- Country: Switzerland
- Topics: General
- Reuters ID: LVA80SYODF3SYY23ZJOF3CXNSKZZ
- Story Text: A group of nine undergraduate students from Switzerland have built a four-finned, omnidirectional, underwater robot that not only resembles a fish, but could help marine biologists observe real sea life and fauna without creating turbulence or disturbing the ocean floor.
Sepios is the brainchild of a group of students from ETH Zurich's Autonomous Systems Lab. Based loosely on an ocean cuttlefish, its four fins each contain nine rays, all with a 270-degree range of motion, and activated by individual servo motors - 36 in total. The fins are fitted to a single central base unit containing a mechanical swim bladder, which allows the robot to maintain a given depth by adjusting its buoyancy.
"We have the base unit in the middle, we have the four outer fin cases with all our servos inside, we have the buoyancy shell made out of carbon fibre, we have our rays, and we do have the latex foil to give propulsion into the water," explained team member Alessandro Schappi.
The 22.7 kilogram (50 lb) aquatic android also includes a live-streaming video camera, water pressure/depth sensor, humidity sensor, laser distance-measuring hardware, and combined accelerometer, gyroscope and magnetometer that allows altitude control.
The robot is controlled by the signal of a 3D Connexion space mouse combined with the data of an onboard Inertial Measurement Unit (IMU). The single force and torque vector is then split onto the individual fins by an allocator which optimises energy consumption.
"We are using this space mouse and we can use it to move around in six degrees of freedom in space," explained Schappi while holding the mouse. "So if we want to dive down we need the two fins on the side to flap up and do a standing wave to dive down. So we just press the space mouse down and as you can see we are diving down. To dive up the opposite, just press it up and we are swimming up. Who wants to (if you want to) dive to the front we can push the space mouse to the front and here you see four waves which give a propulsion to the front. To the back exactly the same."
Sepios's camera and laser also help avoid underwater collisions. "We do have a camera and a laser and with the camera and the laser in here we are able to do collision detection, so that we don't swim into the walls. So if we detect the wall (obstacle) we just turn around and we swim into the other direction," said Schappi.
Its four undulating fins are able to manoeuvre Sepios forward and backward, turn on the spot, or hover - similar to the way a two-finned cuttlefish moves. "We actually set the goal to ourselves to build it omnidirectionally, so we proved to be able to move forward and backward, drift to any side, and also turn around any axis by performing corresponding movements," said Schappi's colleague Martin Moller.
By generating thrust with the fins in angled stances, a variety of acrobatic motions such as barrel rolls are possible.
Sepios's modular design meant the ETH team worked in separate, parallel, teams assembling 4,600 separate parts. The finished model was presented last May, ahead of the students' graduation.
Sepios's flexible latex fins are immune to obstacles, seagrass, and coral - making it potentially well-suited to observing and filming marine life. Its ability to move without disturbing the seabed only adds to its possibilities. Schappi thinks, for instance, that it could also be used in underwater pipeline research, as well as sealife and fauna research.
Moller says Sepios has one yellow fin and three that are blue for a practical, rather than aesthetic reason.
He said: "It took (takes) a bit of time until you get used to steering an omnidirectional robot underwater. That's why we have one fin yellow, so you know where upward and downward is, otherwise you would get confused. But once we had that we were really very flexible, as we expected. And then when we went to the sea of France we were able to cross seagrass without entangling, there was no problem. And we could film some fish with our onboard webcam and project that via a live stream to our laptop and use that for steering as well."
Schappi and Moller insist that Sepios's strength lies not in its speed - up to four metres per second - but its agility.
Tests off the French coast, at Antheor, showed that all Sepios's seals were water tight, while one charge of its battery pack allowed 90 minutes of use, the machine descending to a maximum of 10 metres (33 feet).
Since graduating last summer most of the ETH Zurich team members have gone their separate ways, although Schappi and Moller both hope to develop further aquatic robots. - Copyright Holder: REUTERS
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