Défense
Inertial platforms: iXBlue’s fibre-optic gyro technology

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Inertial platforms: iXBlue’s fibre-optic gyro technology

Défense

Inertial navigation systems are critical items of military hardware, not least because they enable military platforms and weapon systems to determine their position independently. France boasts world-class know-how in fibre-optic gyroscopes and INS technologies.

At sea, ships need to know where they are at all times and to the highest possible accuracy. This has always been a challenge. Once out of sight of landmarks, the only reference points for autonomous position fixing are the Sun and stars when visible (which is seldom the case for submarines). To be both effective and independent of external systems, including GNSS and other satellites, ships need autonomous instruments. Modern inertial systems meet this need by integrating the platform’s motion over time. Fibre-optic gyroscopes, or FOGs, measure and integrate rotation rates to deliver the platform’s attitude while accelerometer output signals are integrated to yield speeds and distances. Sophisticated algorithms use this data to continuously update the platform’s position relative to its starting point, along with its attitude (roll, pitch and yaw), speed and heading.

Thanks to its innovative FOG and INS technologies, French group iXBlue has emerged as a world leader. Fibre-optic devices have two key features: first, they have no moving parts; second, they preserve beam polarisation irrespective of wavelength. Other advantages include lower power consumption and vibration-free operation, a key consideration with regard to acoustic discretion. Performance is theoretically unlimited since it depends primarily on the length of the fibre-optic coil. Put simply, the longer the coil, the higher the accuracy. Availability is also impressive since the technology requires no preventive maintenance and uses no lifespan-limited components.

In addition to producing all the critical components for its core products and testing its accelerometers using the vibrating quartz crystal technology, iXBlue manufactures its own optical fibre in France. The company thus maintains direct control over its key technologies relying exclusively on in-house expertise. Unrivalled know-how — and a growing international standing — have enabled iXBlue to develop a portfolio of inertial products for naval, aerospace and land-based platforms in the civil and military sectors. The four main product families — Quadrans, Octans, Phins and Marins — use fibre-optic coils from 50 to 200mm, resulting in progressively higher accuracies to meet a range of customer needs.

 

 

Drawing on 15 years’ experience, iXBlue has sold more than 4000 INSs worldwide, including systems for European and US spacecraft as well as for some 80% of the worldwide offshore oil industry’s underwater vehicles and robots. Offshore support vessels needing high levels of reliability and accuracy use iXBlue INSs for precision dynamic positioning. Research vessels and hydrographic ships engaged in seafloor mapping also rely on iXBlue products.

Building on experience acquired in the civil sector, iXBlue turned to military applications ranging from inertial navigation to weapon stabilisation and missile alignment for precision targeting. From Asia and Europe to the Middle East and North America, iXBlue products equip surface combatants, submarines and autonomous underwater vehicles. The French Navy selected the Marins INS for the modernisation of its Jean Bart and Cassard air defence frigates, the Phins INS for its La Fayette-class frigates and Quadrans FOGs for some 40 other vessels. In 2016, the company launched a compact version of the Phins INS.

The US Coast Guard selected iXBlue products for various vessels while the Royal Navy chose the Marins family for its new-generation Astute-class SSNs and Queen Elizabeth-class aircraft carriers. In 2016, the Royal Navy made Marins M7 strap-down INSs standard fit for 35 front-line vessels including Vanguard-class SSBNs, Type 23 frigates and Sandown- and Hunt-class MCM vessels. The Marins M7 offers a drift of less than 1nm per 72 hours of surface or submarine navigation without access to a GNSS.

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