A School of Robot Fish

Discover the Jessiko Robot Fish through this interview with Christophe Tiraby, CEO of Robotswim. Jessiko robots are 20cm long and can swim in groups along real fishes. They can localize themselves, detect some obstacles, last hours in the water and are totally autonomous.

This wonderful piece of technology is already available for animating big events, and may one day entertain you in your own pool. So sit tight and read or you are going to miss this chance to know this new robot.

ME: How does the Jessiko robot fish work?

Christophe Tiraby: From the beginning, the hypotheses were really to build a simple robot: a robot that is both easy to build, and very small.

Christophe Tiraby and its creation
Robot fish Jessiko and Christophe Tiraby

There are two servos for the fins, and one more to control the dorsal fin for the buoyancy.

In fact, it's a robot that is indeed rather simple for the mechanical parts, but has a rather complex electronics and software system compared to what you can usually see.

Actually, what we sell [at Robotswim] is not robot fishes, but schools of robot fish. That's why the robots are simple. On the other hand, what is not simple and even our strength is to be able to make them swim together.

ME: How much did you try to copy real fishes?

Christophe Tiraby: The idea was in fact not to copy nature exactly by doing the copy of a real fish. The idea was to use the locomotion of the fish, with fins, but that's it.

What was new here, was to see it as a design product. This robot fish is a human creation, with an object that is cool to watch.

We have received the "Grand Prize of Innovation from Paris" in 2009, in the design category. The jury were designers, and what they liked is that it was an object. In one hand, we copy Nature, but on the other hand, it's a real design product, an artwork, with an aesthetic completely different from a real fish.

Also, what is interesting in using fins, is that it conveys some grace. It's a feeling of "perceived intelligence". People see it like an animal, because they are used to see this kind of undulating movement in real fishes.

The Jessiko Robot Fish

The Jessiko Robot Fish is fascinating to watch

ME: Can this robot be used to do something useful, like monitoring the pool, or the environment?

Christophe Tiraby: We are focused on clients, and right now our clients are in the event field, or for permanent expositions in museums (science or aquatic) and commercial centers. In 1.5 year, we aim for pools.

But for all these markets, we don't need any specific sensors. It's not in our interest to make the robot fish more complex than it already is. So we don't add sensors.

There is no need to look for a use in these robots. It's really a French habit to think that way, but in the end, when people are watching the robots, they are hypnotized. When they are in front of the robots, they don't ask if the robot can give them the temperature of the water. They're just here, watching, looking at it moving.

ME: What are the challenges of making a robot fish?

Christophe Tiraby: First, just like any submarine, you have the sealing.

But what's most difficult is the 3D navigation, which is totally different compared with 2D. When you have a 2D robot, especially with wheels, you can use odometry (counting the wheel turns or step lengths to calculate your current position).

When you move in 3D, either in water or in the air, it is very hard because any little wind, any steam will set the robot off course without it knowing. Therefore, the adjustment is not straightforward, and you're always in some approximation.

Also, you can always say to a wheeled or humanoid robot to just stop, and it won't move. For a 3D robot, you need a feedback control for that.

Another challenge in water is the communication. Unlike in the air, where you can use any kind of communication like Wifi or Bluetooth, it doesn't work in water.

In the water, electromagnetic waves don't go through, or at least it's not that good. So you can forget about video. But you can get a few signals through sometimes.

We chose to use an optic communication. For the Jessiko robot, it's a communication method covered by worldwide patents, and that also work for localization.

Since water tends to filter infrared and shorter wavelengths, we use visible light (wight, green, blue). If you use red light, it starts getting filtered by the water. That's the same reason why in deep sea everything is blue. All the other colors are filtered by the water.

ME: How does each robot fish localize itself?

Christophe Tiraby: It's a beacon system. The main innovation in the Jessiko robots is that they have a searching head that can localize the beacons and other robots in real-time. Since the beacons are fixed, the robots can triangulate their position using the apparent positions of different beacons. (NOTE: It is the same systems that is used by sailors by night with lighthouses.)

That's why there are 2 processors in the robot, with one only doing that: localization, navigation and transmitting messages. (NOTE: If I understood well, they transmit messages just like Morse code, in faster, with their LEDs.)

ME: Do you plan to do a bigger fish in the future?

Christophe Tiraby: For the World Expo in Korea, we are going to make them slightly bigger (like 10%). We do that to put bigger batteries inside, so that they last longer.

We won't do something bigger, because it would require a new design with more articulations. It wouldn't be Jessiko anymore, it would be a brand new robot fish.

Also, we cannot really talk about it, but we are working on a turtle robot. It's a robot a little bigger, suitable for exploration, with a video camera and so on. Jessiko has no room for a camera. We now there is a demand for this kind of exploration robot, so here we are: we're going to make a turtle robot.

A School of Robot Fish

The Jessiko Robot Fish Team

Other comments and important info

The Jessiko robot fish is a condensed piece of innovation and technology. In 20x10x10cm, it has 2 processors and a few motors, and can swim in a school of fish without colliding with its friends or the walls. Quite a performance indeed.

Robotswim has been chosen to animate the French Pavilion at the next World Expo, in Yeosu, South Korea. It will start in May 2012 and last a few months. So the Jessiko school of robot fish will follow the highly successful coordinated dance of Naos from Aldebaran.

As Christophe Tiraby said later in our discussion: "France is a leading country in robotics". And his fishes are yet another proof of it.

The interview was made on August 19th 2011, in French. The text has been translated, and slightly adatped (cut and reordered) for the sake of the article.

Find more about Robotswim's robot fish on their site.

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