We've seen a robotic tuna and robots that swim more or less like people. Now engineers at the Swiss Federal Institute of Technology have built a robot modeled on a sea turtle.
The Naro-Tartaruga is the second generation of the Institute's Naro (nautical robot) project. The original Naro was based on a tuna fish, which the project's Website says is one of the fastest swimmers in the world, with speeds of up to 80kph (49.7mph). The tuna's speed was also cited by the Department of Homeland Security's Science & Technology Directorate as the reason for modeling its autonomous underwater unmanned vehicle (UUV), the BIOSwimmer, after a tuna.
The Swiss Institute's engineers developed their robot tuna with the main goal of a proof-of-concept for bio-inspired locomotion, especially robotic propulsion via flapping fins. Made of fiberglass, the first-generation Naro is 1m (3.28 ft) long, weighs 13kg (28.7 lb), and swims at an estimated speed of 1m per second.
Left, engineers at the Swiss Federal Institute of Technology have built a robot modeled on a sea turtle, shown here in a conceptual drawing, that is capable of underwater autonomous navigation. Right, the robot sea turtle prototype, shown here without its container, is scheduled to make its first dive later this month. (Source: Swiss Federal Institute of Technology)
But the first Naro does not operate autonomously. For their second generation robot swimmer, the Naro-Tartaruga, the Swiss engineers wanted to implement underwater autonomous navigation in addition to remote control. To do this, the robot will be equipped with a variety of sensors for different tasks. These include sensors for pressure, temperature, water flow, and water leakage, as well as gyros, motor encoders, GPS for surface use, and a compass, presumably for underwater use. Its vision sensors are a BlueFox camera from Matrix Vision and its CPU is an Intel i7 dual-core processor.
The engineers decided to use a sea turtle as their model primarily because of its rigid body, which, according to their Website, "is technically much simpler to realize than a [sic] agile body of a fish. The big torso also provides enough space for sensors and batteries which are essential for autonomy." The robot turtle's body is made of aluminum, which will protect all that equipment a lot better than the first Naro's fiberglass hull.
Like the Naro, the second-generation sea turtle robot is also 1m long, but weighs much more at 75kg (165.3 lb). The Naro-Tartaruga is also twice as fast at an estimated speed of 2m per second. It has a diving depth of 100m (328 ft), compared to the Naro's 5m (16.4 ft).
With the Naro-Tartaruga, the researchers say they will be able to provide the first direct measurements of the energy consumed by a robotic flapping fin mechanism. Most systems for creating mechanical flapping fins for use underwater have depended on serial actuation principles. In these systems, one motor drives a box and a second motor drives the fin. These designs call for several different sealed bodies, connected by cables, and an architecture that increases both energy consumption and the risk of leaks.
In contrast, each of the Naro-Tartaruga's fins is driven by three actuators, which include six 200W brushless and two 15W brushless Maxon Motor devices. All three actuate the fin axle independently, but they're contained in a single waterproof body, reducing the risk of leakage and energy consumption.
This looks like a well-thought-out, smart design: rugged materials, equipped with all the needed sensors, and with actuators that better emulate an animal's elegant and powerful fin movements.
Ann, this is great. The number of swimming robots you have described is amazing. This one looks like it could travel large distances, just like real sea turtles. If all these creatures were deployed, we might have to be careful about what we catch when fishing. I am also suprised by the origin of this one and the tuna. Switzerland is a land locked country.
Great article. I would be interested to see how efficient each design is at different speeds. In other words, would the turtle design be more power efficient at lower speeds and the tuna design be more power efficient at higher speeds? I would also be curious to see the comparison of each design under different conditions.
When they say "Autonomous" in reference to robots, to what extent do they mean? I presume that even when they cut the thing loose to swim "autonomously", they still have the ability to take control. Is that the case?
Also, it would seem that autonomous behavior would have to be guided by some set of rules that give the robot some objectives or priorities as to what it is supposed to be doing. Is that the case, or is it just supposed to randomly swim around avoiding obstacles?
Are flippers more efficient than a propellor? Sea creatures use flippers because they are easier to evolve than a bearing mounted shaft, not because they are the better solution.
A device such as this would be semi-autonomous - it would be able to maintain bouyancy and evade obstacles and non-tech-savvy predators by itself, but it needs to be steered to its' target and told what to do when it gets there (either placing or removing limpet mines, I suppose)
Hi ttemple, You are correct in regards to autonomous. The robot can manuever without an ambilical cord of wires. Sensors along with software will guide the robot based on a set of rules allowing it to be used for specific tasks such as tracking oil slicks or other environmental conditions of interest to researchers. Thanks for another great robotics article Ann!
Thanks, Lou and gsmith. There's a surprising number of swimming robots, whether humanoid or animal-oid. Lou, good point about fishing! gsmith, I also noticed some major improvements in the rev 1 and 2 of the naro.
Thank God the Swiss are funding stupid things like this..... Oh crap; I finally read the rest of the first paragraph. Somewhere I knew that the U.S. Govt might do something like automate a fish. Who better than F-ing Homeland Security to manufacture a spy fish. Wait until the Navy finds out that another dept is infringing on their territory. This flapping contraption reminds me of the first attempts to make a flying machine that flapped.
On the other hand may be I could get a grant from Homeland Sec. to develop a flapping airplane.
The Chief of Naval Operations once stated in a speach that the U.S. Navy has three enemies: The Soviet Union, the U.S. Air Force and Hyman Rickover. Now we'd have to add Homeland Sec.
mrdon, thanks for that explanation. Robots are becoming more autonomous all the time, as sensors, processor and software become more powerful and/or increasingly sophisticated.
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