Question 1

How does an inertial navigation system work without external signals, and how accurate is it?

Accepted Answer

An inertial navigation system (INS) relies on raw data from an inertial measurement unit (IMU), which is a key component of the overall system. The INS enhances this data by using advanced algorithms to deliver accurate, real-time information about location and orientation. By combining data from accelerometers and gyroscopes, the system enables precise navigation without depending solely on external signals like GPS or GNSS. Safran offers options including ring laser gyro (RLG) and fiber optic gyroscope (FOG) based systems, in addition to their primary high accuracy gyro (HRG) technology, providing different performance options for mission requirements. MEMS gyro technology, utilized in our STIM products, delivers stabilization, guidance, and control capabilities, particularly beneficial for platforms with size, weight, and power (SWaP) constraints. Learn more about how IMUs support navigation in our IMU Application Guide.

Question 2

What are inertial navigation systems used for?

Accepted Answer

Inertial Navigation Systems (INS) play a crucial role in providing accurate north-finding capabilities for pointing and aiming applications (Radar and targeting), as well as Navigation for vehicles, especially in GPS-denied environments. These systems are essential for maintaining precise heading data to ensure accurate navigation and targeting without relying on GPS signals. By utilizing INS technology, vehicles can effectively adjust their orientation and direction for radars and weapon systems, minimizing the risk of errors due to changes in angles or external factors like vibrations and shocks. In situations where immediate and precise navigation is required, INS technology proves to be a valuable tool for ensuring the safety and effectiveness of operations.

Question 3

What types of applications use inertial navigation systems?

Accepted Answer

AviationUsed in commercial and military aircraft for reliable flight navigation and control in all environments. Autonomous SystemsEssential for drones and autonomous vehicles, providing accurate positioning and motion tracking for safe operation. Land SystemsCritical for missiles and military platforms in contested areas where GPS is unavailable, ensuring resilient navigation and pointing of mission critical radar/kinetic systems. MaritimeEmployed by ships and submarines for consistent navigation when satellite positioning is not possible, particularly underwater or in tough conditions. To learn more, view our use cases:Equipment Pointing & Radar Directional Capabilities for Defense ApplicationsLand Vehicle Navigation in GNSS Denied Environments for Defense Applications

Question 4

Can an IMU be used for navigation?

Accepted Answer

An IMU can provide the necessary motion and rotation measurements for navigation; however, an IMU and INS are not the same. An IMU consists of accelerometers and gyroscopes that measure acceleration and angular rate. In contrast, an INS utilizes data from inertial sensors, along with navigation algorithms, to calculate position, velocity, and orientation. Kalman Filters assist in the transition from rates and accelerations into a navigation solution tailored to the particular usage. An IMU may be integrated into a larger navigation system, while a complete INS offers a ready-to-integrate navigation solution for platforms operating in environments where GNSS signals may be unavailable or unreliable.

Question 5

How to choose an inertial system for autonomous vehicles?

Accepted Answer

Choosing an INS for an autonomous vehicle depends on several factors, including the platform, required accuracy, mission duration, operating environment, size and weight constraints, and how the system will interact with other navigation sensors. It is important to consider aspects such as heading accuracy, position drift, alignment time, environmental ruggedness, Size, Weight, and Power (SWaP), and the ability to maintain navigation during GNSS outages. For autonomous vehicles operating in GNSS-denied environments, long-term inertial stability is particularly crucial, as navigation errors can accumulate over time without external updates. We offer inertial solutions for land, naval, air, and space applications, allowing our systems to be tailored to specific platform and mission requirements. Not sure which inertial solution is right for your platform? Contact our team to discuss your navigation needs

Question 6

What should I look for when comparing inertial navigation systems for marine applications?

Accepted Answer

When comparing marine INS, it’s important to consider more than just inertial accuracy. Key factors to evaluate include navigation drift over time, heading accuracy, endurance without GNSS, reliability, environmental qualifications, size and power requirements, as well as integration with onboard navigation or combat management systems. Safran Federal Systems offers a comprehensive portfolio of naval INS solutions tailored for surface vessels, submarines, and amphibious platforms. The Argonyx model provides various performance levels suitable for surface vessels, while the Black-Onyx is specifically designed for submarines requiring long-duration autonomous navigation capabilities.

Question 7

Is INS more accurate than GPS?

Accepted Answer

INS and GPS/GNSS serve different purposes, so one is not universally "better" than the other. GNSS provides highly accurate absolute positioning when satellite signals are available, while INS can continue providing navigation information without relying on external satellite signals. For this reason, INS and GNSS are often used together. GNSS can provide periodic position updates that help limit inertial drift, while the INS can maintain navigation through temporary signal loss, jamming, or other GNSS disruptions. For missions where GNSS may be denied or unreliable, a high-performance INS provides an important layer of navigation resilience.

Question 8

Can inertial navigation systems be jammed?

Accepted Answer

An INS does not rely on GPS or GNSS signals to calculate navigation data, which means that conventional GNSS jamming does not hinder the operation of the INS. This makes the INS particularly valuable for navigation in environments where GPS or GNSS signals are unavailable. However, when an INS operates without external updates, it will experience navigation drift over time. The degree of this drift depends on the performance of the inertial sensors and the length of operation. By combining INS with GNSS and other reliable navigation inputs, it is possible to maintain accuracy when external signals are available and ensure continuity when they are not.

Question 9

Why is north finding important, and how accurate does it need to be for equipment pointing & radar directional capabilities?

Accepted Answer

Accurate north finding is essential for precise equipment pointing, which can directly impact mission success. Weapon systems and radar platforms rely on highly accurate heading information to correctly designate and engage targets. A robust navigation system that delivers real-time heading data is therefore critical in defense applications. An inertial navigation system (INS) can continuously refine its orientation without external signals, enabling precise targeting and weapon designation. Achieving accurate fire control involves determining true north, assessing wind speed and direction, and calculating the target’s elevation. Geonyx, which leverages HRG technology, uses motion and rotation sensors to deliver reliable navigation and heading calculations, making it well-suited for ground-based missions.

Inertial Navigation Systems

Inertial Navigation for Defense Applications

Precision North Finding & Navigation Systems Across Domains

Land

Naval

Air

Space

IMUs & Gyros

HRG Crystal Technology

Use Cases for Inertial Navigation Systems

Visit our PNT Library to learn more about how our INS systems can support the warfighter.

Frequently Asked Questions