Software Technology

This page explains the Dynamic Offset Estimation used in combination with AK0991x series products.

Issue in electronic compass applications

The electronic compass is used to detect the direction that users are facing in a smartphone map application. However, the correct direction may not be obtained due to the magnetic parts used inside the phone. For example, parts using magnets, such as speakers, are subject to magnetic offsets, which can adversely affect the electronic compass (azimuth errors). In order to eliminate azimuth errors caused by the offset magnetic field, the effect of offset magnetic field must be removed from the data measured by sensors and adjusted. To solve this issue, a technique for accurately separating the offset magnetic field from the geomagnetism is required.

Figure 1. Conceptual diagram of offset magnetic field and geomagnetism

What is DOE? 

AKM has developed a technology (DOER) that separates the offset magnetic field from the weak geomagnetism and automatically adjusts the effect of offset magnetic field. DOER focuses on the distribution of geomagnetic data on the surface of a sphere around an offset magnetic field as the terminal moves naturally (vertically, horizontally, tilting, etc.) when using a smartphone.

By estimating and adjusting the magnitude of the offset magnetic field (Center of distribution: O) from the magnetic field data (distribution data P1 to P5) when the smartphone is in various orientations, the azimuth angle with less error can be calculated. Even if the magnitude of offset magnetic field changes during use, DOER is a robust tuning algorithm because it can be tuned to follow the changes.

Figure 2. Conceptual diagram of DOER

In addition to expanding sales of AK0991x series, DOER has been used in many mobile phones, smartphones, and tablets around the world.  In recognition of these achievements, in 2012 AKM received the "ONSHI Invention Award" from the Institute of Invention, which is the highest award for inventions nationwide, sponsored by the Institute of Invention.