30 May 2012


Cycloïd-E is a sound/kinetic sculpture created by the brothers Andre and Michel Decosterd in 2009. The sculpture consists in five metallic tubes equipped with sound sources and with measuring instruments capable of making them resonate according to their rotations, creating an hypnotic dance. See more;

"We started experimenting with the pendulum, which is at the basis of mechanical oscillating circuits. Because of its constant period, it represents in a way the harmony in the exchanges between kinetical and potential energies. A pendulum only consists in a mass at the end of an arm. To increase the diversity of the movement and obtain an object with more visual and sound attractiveness, we linked number of pendulums with each other so that they would move in the same plane. In order to cancel the effect of gravity, the end of this chain was fixed to a vertical axis, with the chain moving in a horizontal plane. The arm segments of the arm were slightly staggered to allow them to superimpose each other while rotating so that the chain may cover the complete surface of a circle. Since gravity has no longer an effect on the movement, a central engine gives impulsions, which produce the global movement. As a consequence, we obtain a system that does no longer move in a determined fashion, but in a chaotic, unforeseeable way. Its behaviour is fascinating because of the constant variations of the trajectory of its arm and the constant changes in speed. Slow motions of the arm can transform itself in a rapid rotation of one of the segments. These variations come in part from the random impulsions given by the engine, but mostly from quick transfer of kinetic energy between the different segments of the arm, transfer due to the rigidity of the segments in this aggregate of masses, each carried away by its inertia. In order to conveniently associate the perception of sound and movement of the object, each segment is equipped with a loudspeaker. Each of them emits a sound directly related to its speed and its position, but also in relation to the state of unfolding of the whole structure and finally directly related to the density of the fluctuations. Since this structure has a diameter of about ten meters and important speeds of displacements, additional sound effects are generated, such as resonances, beats, Doppler effects … 

The music - The articulated arm of cycloïd produces music. The quicker its movements, the louder, enriched and brilliant the spectral tone becomes. The music expresses the mood of the machine, for example with an orchestral scream. Each part of the arm is an instrument which produces its own sounds depending on its activity. These tones come from orchestral instruments like the piano, cello, violin, clarinet, and various percussions. The tones are in perpetual evolution. The interpolation of their spectres produces all sorts of hybrid resonances. From these spatial movements an evaluative harmony is born, a kind of topology of tones which integrates the idea of tone trajectory." - Andre and Michel Decosterd

"Structure and measuring device - The technical realisation of the structure is complex. The random dynamic of the structure generates a number of forces with a wide variety of amplitudes and directions, which are very difficult to calculate. Centrifuge forces exerted on the arm during a rapid extension of the system generate shocks followed by oscillations which, given the importance of the mass of the structure, can enter into resonance and compromise the fluidity of the movements. The articulations must have a great rigidity to withheld eventual shocks. The choice of material for the arm was dictated not only by factors of static and dynamic resistance but also by the material’s vibratory characteristics since the segments play a role as sound interface. The structure was constructed using high resistance aluminium and all the joints were welded. The rotation axes are made of steel and are held in roller bearings with conical rollers. The interior of the tubes is partially covered with polyurethane foam for an optimal management of resonances. The interior of the axes is equipped with incremental encoders and gyrating connectors connected to the central computer. A hydraulic pump with radial pistons operates the sculpture."