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Artificial rays take to the water

09 May, 2007

At the 2006 Hannover Fair, Festo fascinated visitors to its stand with remotely-controlled, pneumatically-powered "fish" swimming freely in a vast tank of water. This year, the tank was back but this time it was populated by uncannily realistic "manta rays", again swimming freely under remote control (below).

Festo Aqua ray

Festo engineers analysed the way that rays flap their "wings" in a bird-like manner to propel themselves efficiently through water. They then developed a mechanical equivalent based on the companyís "fluidic muscle" technology, consisting of elastomer tubes that contract when filled with a fluid.

A water-driven vane cell pump generates the raysí propulsion energy, which is conveyed via specially developed valves to three pairs of fluidic muscles. As they contract, their force is transferred via artificial "tendons" to the wings and the tail which, in turn, transform the 55mm tendon travel into more than 550mm of wing movement. The photo below shows the equipment under the ray`s skin.

Festo ray interior

As well as flapping their wings, the rays can be operated as hydrostatic gliders, thus saving energy.

Festo has also used its manta ray expertise to develop a ray-shaped helium-filled balloon with a flapping-wing mechanism that "swims" through the air.

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