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JellyBot

Space Apps 2015 project

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Introduction.

This site aims to show our work in the 2015 edition of Space apps challenges, a bioinspired drone aimed at large space stations with zero gravity constraints. Other jellyfish-based systems were built for underwater movement, like this one from Festo.

Festo AquaJelly

We noticed that there are very strong similarities between underwater and zero gravity environment. In particular we have seen that there is no need of a force balancing the weight and, because of this, no need of high thrust device. Our main idea is to build a drone that takes the most of this particular conditions and uses some of the technologies already developed for underwater vehicles.

An overview on jellyfishes

Jellyfishes (part of the phylum Cnidaria) are the most efficient swimmers of all animals. Their ability to create vortex to move granted them a 48 percent lower cost of transport (in terms of energy spent in movement compared to the amount of oxygen and food consumed) than other animals. They move in water by radially expanding and contracting their bell-shaped bodies to push water behind them. They pause between the contraction and expansion to create two vortex rings. Muscles are used for the contraction of the body, which sheds the first vortex and pushes the animal forward, but the mesoglea is so elastic that the expansion is powered exclusively by relaxing the bell, which releases the energy stored from the contraction. By doing so, the second vortex ring rolls under it and begins to spin faster. This sucks in water which refills the bell and is pushed up against the centre of the body, giving it a secondary and "free" boost forward.

jellyfish

This movement and his extremely high efficiency are the bases of our idea of zero g drone.

How JellyBot works

JellyBot is a bioinspired drone which takes inspiration from how jellyfishes manage to move in water by expanding and contracting their body and thus creating a ring vortex for propelling. We developed a model based on the vortex pulsed jet as many different scientists have already shown in literature, and Festo realized in water. Since we are working in a zero gravity environment, we do not need to generate lift and therefore we believe this kind of propulsion might be very effective, even in carrying 2-5 kg payloads. The payload will be put in a sphere on top of the mechanism, which will also contain the brushless electric motor (100W approximately), the battery and the control electronics. The drone will be safe thanks to low operating speed and material impact tolerance that we have considered throughout the building process.

The developing process

We have developed the CAD model of the single arm and of the group of 8 tentacles together then we have simulated the 2d lumped parameters dynamics to show the feasibility of our proof of concept. Then we populated a Gazebo world with the internals of the Zyria module of ISS to show how the drone can operate in a zero-g environment.

Further applications

This type of propulsion can also be considered as an efficient way to further enhance the oceanography studies since we would be able to use very low power and have very long autonomy which is needed in the remote areas where the studies are normally carried.

Authors and Contributors

Riccardo Castellotti Tommaso Sartor Giorgio Valsecchi Salvatore Alberto Buccellato Vladimir Pietro Cravero Yuri Iozzelli