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Micron Digital Claims to Have Eliminated Drifting in IMUs

May 11, 2020 by Luke James

The company claims that they have developed a drift-free inertial measurement unit (IMU), which would be the world’s first if true.

An internal measurement unit (IMU) is used in a computer to track position over time using a combination of accelerometers, gyroscopes, lasers, or magnetometers. While they are more accurate than GPS and other satellite tracking systems, IMUs are not without their faults. 

Over time, tiny measurement errors add up and lead to a difference between where the IMU thinks the computer is and where it actually is—this is a problem known as drift. And as time goes on, drift gets worse. 

All IMUs suffer from drift, however, Micron Digital has recently claimed to have developed a new IMU that does not—ROMOS, the “world’s first drift-free tracking chip”.

 

Why Drift Is A Problem

There are two types of position tracking system: outside-in and inside-out. The former uses external references, such as GPS, to track position. In contrast, the latter uses internal sensors such as IMUs. It is often the case that systems will use a combination of both systems for the best results, with the system continuously checking GPS to correct for any obvious IMU drift errors.

However, not all IMUs are the same. Those that are found in consumer-grade products, where IMU accuracy is not so critical as in other more sensitive applications, have the highest amount of drift—some come in at values over 7,000 kilometers per hour. Although this can be heavily mitigated with calibration, it illustrates our point and the importance of using GPS in combination with an IMU. 

At the opposite end of the IMU spectrum are those used in highly sensitive and specialized applications, such as those used underwater by submarines. These IMUs can cost up to US$1 million per unit but still suffer from drift of around up to 2 kilometers per day, meaning that it is still necessary to use GPS in combination with them. Although this may not sound like a whole lot, it could be in a scenario where those on board need to be rescued. 

 

ROMOS from Micron, a so-called “drift-free” IMU.
ROMOS from Micron, a so-called “drift-free” IMU. Image credit: Micron Digital.

 

Micron’s ‘Drift-Free’ IMU

According to Micron, ROMOS emits drift-free orientation and position data in millimeters to a host device or processor. Unlike conventional IMUs, additional external reference signals, such as those from GPS, are not required to compensate for drift error. Position data is generated at a high rate through internal MEMS-based inertial sensors for direct use in the host application. 

According to Micron, ROMOS is able to achieve unprecedented levels of performance with “core calculations in a higher-dimensional space before dropping down to three dimensions.” Understandably, the company has remained tight-lipped when it comes to the details. 

What is known, however, is that the ‘ROMOS process’ involves several steps. Raw sensor data that is generated much in the same way as any other IMU. This data then goes through primary filter algorithms, a static calibration filter and Micron’s proprietary RealMotion algorithm. Before ROMOS outputs the final position calculation, it goes through an AI smoothing function. 

 

Applications for the ROMOS IMU 

If it lives up to Micron’s promises, ROMOS will find applications in all the same places as conventional IMUs. These include the more “basic” examples like consumer electronics and navigation systems to the more “advanced” like autonomous vehicles that require low-latency and high-accuracy positioning or robotics applications that require precise movements in locations that are not covered by GPS.