Sagem, Coriolis and inertial navigation

Montluçon, Sagem’s (Safran group) historic base in the centre of France, was the last stop of the pre-Eurosatory press tour last week. It was the occasion for FOB to discover the company’s new Coriolis site. Named after the famous French mathematician Gaspard-Gustave Coriolis, this centre, unique in Europe, is entirely dedicated to the production of inertial navigation systems for the CAESAR, Airbus A400M, Rafales and other major equipment of the French armed forces.

Salem's new Coriolis site, a glass and steel giant entirely dedicated to inertial navigation (Photo Credit: Sagem)

Sagem’s new Coriolis site, a glass and steel giant entirely dedicated to inertial navigation (Photo Credit: Sagem)

The Coriolis building, a glass and steel giant that covers almost 9,000m2, was a €50m investment, 10% of which came from local, national and European authorities. Almost a third of the surface is occupied by cleanrooms for the production and assembly of the hemispheric resonator gyrolasers and gyroscopes necessary to inertial navigation systems: a technology that France is one of the (very) rare countries to master. Like a compass, the inertial navigation system can calculate the direction and distance covered by a moving platform (from a missile to a nuclear submarine) and to instantly determine its position. To achieve this, the system uses a series of inertial sensors, generally three gyroscopes and three accelerometers.

Despite the detailed explanations given by Patrick Chambon, in charge of communications for the Montluçon site, to be perfectly frank it is difficult for me to give more details of the principles behind these technological jewels. I’d rather give you a snapshot of what I saw during this site visit.

Because beyond the extremely advanced technologies mastered here by Sagem, the installation itself is impressive because of its atmosphere. For a non-specialist such as myself, the rooms in the Coriolis building reminded me first and foremost of the ultra-secret military laboratories characteristic of US blockbuster films.

one of the many "with rooms" on which Sagem produces its vibrating hemispheric gyrolasers and gyroscopes (Photo credit: Sagem)

one of the many “with rooms” on which Sagem produces its vibrating hemispheric gyrolasers and gyroscopes (Photo credit: Sagem)

Everything here is white, pure. Starting with the very air itself, which is constantly recycled. The air in the cleanrooms in which the most critical steps of the process are undertaken respect the ISO 4 norm: it thus contains less than 83 particles the size of a micrometer per m3. A nightmare for leukophobics, Coriolis has a limited colour palette. Apart from the dominating white, there are just the yellow lines “to-not-cross-under-any-pretext” and the reassuring red of the fire extinguishers.

The omnipresent machines have practically replaced technicians (the man/machine ratio must be around 1:20). Each machine has a specific task with particularly exotic names “machining of the GRH resonator”, “laser block clarifying” or, my favourite “Molecular docking and bonding GLC 16 & GLC 32” (the translations are our own and may not be exactly what Sagem would have chosen!). These machines also prove the importance of the part played by French SMEs (small and medium enterprises) in the Coriolis adventure. The list of the companies involved gets longer and longer from room to room and one loses count of the CLIMATS, Voumard, Corelec and ADCs which each have a unique know-how. Optimistic, Sagem has adopted a modular structure and has left space for more tools to be added to increase the production capacity if the demand should warrant it.

After an intensive hour long visit I finally found a tool that links this ultra high-tech bubble to the outside world: a Texas Instruments calculator!