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FOG vs MEMS: An Introduction to Different AHRS Technologies

As we have introduced before, our POLAR-300 AHRS has shown its exceptional performance against a Kearfott AHRS based on FOG technology

Attitude and Heading Reference Systems that may be found in the market are based on Mechanical Gyros, RLG (Ring Laser Gyroscope), FOG (Fiber optic gyroscopes), and MEMS (Microelectromechanical system) technologies. The first one was replaced by FOG systems, which is now competing with the MEMS-based AHRS to prevail in the market.

 

Source: An Update on KVH Fiber Optic Gyros and Their Benefits Relative to Other Gyro Technologies

 

Antenna stabilization, agricultural machine control, and general vehicle navigation are the battleground where MEMS and FOGs face off.

FOGs provide very low noise that enables extremely accurate navigation as high levels of noise translate to positional inaccuracy. Bias instability is also a key characteristic as maintaining position and delivering precise turning measurements is essential to staying on track with accuracy even in GNSS denied environments. However, these systems are bigger, weightier, and more expensive than the MEMS-based systems. Additionally, FOGs systems are affected by humidity and their accuracy may be reduced when operating on irregular or pot-holed runways.

Although MEMS solutions have higher Bias Instability that results in degraded navigation or stabilization/pointing solutions, the development of MEMS industry and the advancement of the software algorithm and filters have allowed a decrease in its weaknesses and they are beginning to take market share away from traditional FOG applications.

Applications like robotics and UAVs need subsystems and components with a reduced size and weight, and the latest MEMS sensors are very small and power-efficient compared to FOG-based systems. These systems can provide outstanding dynamic information and attitude data when in dynamic environments, like ground vehicles, aircraft, and vessels. Additionally, if this was not enough, the cost of MEMS is typically less than half of a quality FOG.

UAV Navigation’s POLAR AHRS is the only high-performance AHRS and INS system with a MEMS-based in its class to offer a quaternion-based, drift compensated sensor fusion algorithm operating with full 32-bit floating-point precision at update rates as high as 500 Hz. A quaternion-based solution ensures reliable and efficient operation without the traditional problems associated with gimbal lock. The high update rates ensure the availability of system states with minimal latency, which is a crucial requirement for high-performance control systems. Despite being designed for aeronautical applications, which we have been investing in for years to get the best estimation logics, our AHRS has shown outstanding performance on terrestrial and maritime operations. Additionally, due to the higher cost of Fiber Optic Gyros against MEMs, the POLAR-AHRS provides a complete INS solution at the same price of just one fraction of a FOG-based AHRS.

All these reasons have made many antenna or camera manufacturers select the POLAR AHRS family as their solution for pointing and stabilization.

To achieve the highest levels of precision in attitude estimation and great performance, UAV Navigation has been investing in years of research and development, evaluating every single unit that leaves the office and looking for ways to improve the system continuously. 

Contact us to get an outstanding solution with all the advantages of MEMS-based systems with the POLAR AHRS.
 

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About

UAV Navigation is a privately-owned company that has specialized in the design of flight control solutions for Unmanned Aerial Vehicles (UAVs) since 2004. It is used by a variety of Tier 1 aerospace manufacturers in a wide range of UAV - also known as Remotely Piloted Aircraft Systems (RPAS) or 'drones'. These include high-performance tactical unmanned planes, aerial targets, mini-UAVs and helicopters.