Motion Sensing Stack with Out-of-Plane Magnetometers
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Solution Overview
Problem
Inertial measurement units (IMUs) face challenges with 6DoF tracking accuracy due to limitations in fusing data from multiple sensors, leading to inaccuracies in determining device acceleration and location.
Innovation Solution
A motion sensing stack comprising a 6D or 9D IMU system that includes a 3D accelerometer, 3D gyroscope, and a plurality of 3D magnetometers, with at least one magnetometer positioned out of the plane of the others, along with a signal processing unit for data fusion and calibration, to enhance tracking accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If data fusion is performed using traditional IMU methods, then device acceleration and location can be determined, but tracking accuracy deteriorates due to sensor limitations and drift
Solution Approach 1:
The patent combines multiple magnetometers (at least four, with at least one out of plane of the others) with traditional IMU sensors (accelerometer and gyroscope) to create an enhanced sensing system. This merging of sensors allows for cross-validation and complementary data fusion, where the magnetometers provide absolute orientation references that counteract the drift problems of traditional IMU sensors, thereby improving both measurement precision and reliability simultaneously
Solution Approach 2:
The patent introduces an additional spatial dimension by positioning at least one magnetometer out of the plane of the other three magnetometers, creating a three-dimensional sensor arrangement. This dimensional enhancement provides better geometric distribution for magnetic field measurements, improving the accuracy of orientation determination and enabling more robust error correction through multi-dimensional data fusion
2Measurement precision
If multiple magnetometers are added to improve orientation accuracy, then 3D orientation estimation is enhanced, but device complexity increases
Solution Approach 1:
The patent adds a third spatial dimension to the magnetometer arrangement by positioning at least one magnetometer out of the plane of the others. This dimensional enhancement improves orientation estimation accuracy by providing better geometric coverage for magnetic field measurements, while the systematic integration into the existing IMU framework keeps the complexity increase manageable
Solution Approach 2:
The enhanced magnetometer system performs self-calibration and self-correction by using the redundant measurements from multiple sensors to identify and correct errors automatically. The system uses the magnetic field data to correct drift in accelerometer and gyroscope measurements, and the sensors collectively compensate for individual sensor failures or inaccuracies, reducing the need for external calibration equipment and manual intervention
Data Source
AI summary
Embodiments of the present disclosure are directed to various systems, methods and apparatuses of a motion sensing stack, comprising a plurality of magnetometers. Preferably at least four magnetometers are included and at least one magnetometer is out of the plane of at least three other magnetometers. Preferably, the stack includes an 18D IMU (inertial measurement unit). Preferably, the 18D IMU features a 3D accelerometer, a 3D gyroscope and at least four 3D magnetometers. Alternatively, optionally a 9D IMU is provided, comprising a 3D accelerometer, a 3D gyroscope and one 3D magnetometer. The IMU may optionally be MEMS (microelectromechanical system) based.