HRG Crystal

The game-changing technology

The HRG Crystal is based on a disruptive yet mature inertial technology, patented by Safran Electronics & Defense. It's a Hemispherical Resonator Gyro (HRG), a device that is widely recognized for its compact design, versatility and reliability. Because of these qualities, the HRG Crystal spans a wide range of civil and military applications, from portable optronics for infantry soldiers to the latest launch vehicles, plus armored vehicles, ships and planes.




How the HRG Crystal works

The Hemispherical Resonator Gyro, or HRG, is used to measure the rotation of a platform, whether aircraft, ship, tank or other vehicle, to calculate its exact position and attitude. Applying the same inertial principle as Foucault's pendulum, plus the resonance principle that can make a crystal wine glass "sing", the HRG Crystal does not need to communicate with the outside to determine a position, making it perfectly undetectable and autonomous.

Download the
HRG Crystal Brochure



Inertial navigation using the resonance principle

The Hemispherical Resonator Gyro, or HRG, is used to measure the rotation of a platform, whether aircraft, ship, tank or other vehicle, to calculate its exact position and attitude. A stationary resonance wave is maintained electronically inside a silica hemisphere called a resonator. Using the same principle as originally discovered by Léon Foucault, with his pendulum experiment in 1851, this resonant wave stays fixed in relation to an inertial reference (for example, stars), like a pendulum that continues to oscillate in a fixed plane despite the Earth's rotation around its own axis.

By measuring the relative angle between the vibration plane and the resonator, we can calculate the rotation of the aircraft, ship or other vehicle, and then deduce, using inertial principles, its position and orientation.




Unlike most other inertial technologies, the HRG Crystal is totally unaffected by its surroundings (vibrations, extreme temperatures, shocks, etc.), giving it a virtually unlimited and maintenance-free lifespan (MTBF of 1 million hours). Its brand-new design, optimized combination of size/weight/power and total stealth make it unrivaled in the inertial navigation market, as a technology that will be leading the way for many years to come. Furthermore, it still has considerable headroom for growth, and Safran continues research & development to further improve the performance of the HRG Crystal and expand its scope of application.



HRG Crystal in figures

A SWaP Optimized System

Low Power Consumption
< 1.5 W

Small Dimensions
34 x 37 x 37 mm

Low Weight
50 grams

Environmental Stress Immunity
Vibration, Acceleration, Mechanical, Shock

Withstands extreme temperatures:
- 95°C to + 155°C

Highest reliability on the gyro market

Total Stealth

Maintenance Free

MTBF: > 1,000,000h



A single technology for multiple applications

Building on Safran Electronics & Defense's proven expertise in the design and production of inertial systems, the HRG Crystal is now a mature, multipurpose technology. It is designed to operate in all environments, from the depths of the oceans to outer space, for both civil and military applications. Its remarkable precision and reliability makes it perfectly suited to navigation, pointing, targeting and stabilization.




HRG Crystal: the culmination of 70 years of inertial navigation expertise

Safran Electronics & Defense is one of the few companies in the world today to design and produce, in volume, devices based on all inertial technologies: mechanical, optical, resonating and the Hemispherical Resonator Gyro. Because of this wide-ranging expertise, we can address the specific requirements of each customer, whether civil or military. In short, we can state with confidence that the HRG Crystal uses the most disruptive and versatile inertial technology in today's gyro market.

Safran Electronics & Defense's
inertial navigation systems




Safran Electronics & Defense's fleet of gyros operating around the world

150,000 resonating gyros sold
230,000 mechanical gyros sold
100,000 optical gyros sold



> Credits
© Dominique Sarraute
© Daniel Linares/Safran
© Marc Scudeletti/Safran
© Alain Ernoult
© Safran Vectronix
© ESA/CNES/Arianespace/ArianeGroup
© Philippe Stroppa
© Cockerill 3000
© Freepik
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