Bionic penguins fly through water … and air

April 27, 2009 The latest example of biomimicry in robotics to cross our desk is from German electrical automation company Festo, which has used the shape of the acquatic, flightless bird to construct two different types of bionic penguins. The AquaPenguins use the bird's hydrodynamic body contours and wing propulsion to allow the robot to maneuver in cramped spaces, turn on the spot and, unlike their real-life counterparts, swim backwards. The larger helium-filled AirPenguins use the same principles to lift the usually flightless bird into the air.

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Drawing inspiration from nature for the design of robots allows designers to take advantage of millions of years of design refinement through evolution and natural selection. Although penguins are slow and clumsy on land, 40 million years of evolution has resulted in a perfectly contoured body that makes them extremely energy-efficient in water and capable of high speeds. It was these attributes, in particular, that Festo sought to emulate so they could translate the penguin's mechanics into industrial applications.
For the AquaPenguin, the wing skeleton is comprised of spring steel elements embedded in an elastic matrix of silicon. This lets the wings twist to an optimal angle with each stroke through the water. The pitch angle can also be regulated, giving the robotic penguins their maneuverability.
The head, neck and tail segments are based on a new 3D Fin Ray structure, derived from the anatomy of a fish's fin, which allows the penguin to change its “organic” shape to let it move in any direction. The bending structure consists of flexible longitudinal struts with "circumferential connecting elements" that maintain the shape of the elastic skin, and help to steer the robotic penguin horizontally and vertically.
The same basic design principles are also adopted by the AirPenguins, although the 3D Fin Ray structure is modified slightly. To give the AirPenguin elevation, Festo designers filled a ballonet, or small balloon, with about one cubic meter of helium, which can lift about 1 kg. A system of carbon fiber rods and joints, moved by wires and pulley, are used to guide the penguins through the air.
With the AquaPenguins, a powerful electric motor, used to control the rate of flapping, and leverage system to regulate the amplitude of the flapping wings combine to almost perfectly imitate the kinematics of the penguins’ underwater “flight”. The flapping cycles are virtually self-regulating, with little effort needed to maneuver the bird.
The AirPenguins, on the other hand, rely on a series of mechanisms, called actuators, to control how often their wings flap and whether they move forwards or backwards, up or down.
Festo didn’t limit their study to penguins in searching for ideas. Researchers also looked to bats and dolphins to help design the penguins' intelligent 3D sensor system. The AquaPenguins are fitted with special 3D sonar to analyze their surroundings, using broadband ultrasound signals to constantly measure distances to the sides of the water basin, avoid collisions and navigate autonomously or as a group. A separate pressure sensor is used for greater depths.
The same principles are used to navigate the AirPenguins, but their movement is monitored by invisible ultrasound “transmitting stations”.
Festo built the penguins to create opportunities in design and automation technology. Already the company has had some success, using the design of the penguin's body to develop a mechanical hand, called the BionicTripod with FinGripper. According to Festo, the BionicTripod has greater "pick-and-place applications" than conventional tripod designs while the FinGripper has the flexibility to securely grip and deposit fragile or irregular-shaped objects.
Festo is also anticipating the intelligent sensors used by the AquaPenguin will find numerous industrial uses.
The bionic penguins are on show at this year's Hannover Messe Trade Exhibition in Germany.