Skewed-redundant Hall-effect Magnetic Sensor Fusion for Perturbation-free Indoor Heading Estimation

Abstract

Robust attitude and heading estimation with respect to a known reference is an essential component for indoor localization in robotic applications. Affordable Attitude and Heading Reference Systems (AHRS) are typically using 9axis solid-state MEMS-based sensors. The accuracy of heading estimation on such a system depends on the Earth's magnetic field measurement accuracy. The measurement of the Earth's magnetic field using MEMS-based magnetometer sensors in an indoor environment, however, is strongly affected by external magnetic perturbations. This paper presents a novel approach for robust indoor heading estimation based on skewedredundant magnetometer fusion. A tetrahedron platform based on Hall-effect magnetic sensors is designed to determine the Earth's magnetic field with the ability to compensate for external magnetic field anomalies. Additionally, a correlation-based fusion technique is introduced for perturbation mitigation using the proposed skewed-redundant configuration. The proposed fusion technique uses a correlation coefficient analysis for determining the distorted axis and extracts the perturbationfree Earth's magnetic field vector from the redundant magnetic measurement. Our experimental results show that the proposed scheme is able to successfully mitigate the anomalies in the magnetic field measurement and estimates the Earth's true magnetic field. Using the proposed platform, we achieve a Root Mean Square Error of 12.74°for indoor heading estimation without using an additional gyroscope.*Preprint Version-Accepted article in the 4th IEEE International Conference on Robotic Computing.

Improving Attitude Estimation Using Gaussian-Process-Regression-Based Magnetic Field Maps

“…Unlike position localization, attempts to estimate attitude indoors tend towards detecting and rejecting perturbations in Earth's magnetic field [4][5][6]. However, the methods from these works do not easily extend to full 3DOF roll, pitch, and yaw estimation and require multiple magnetometers.…”

“…Typically, m = 1 when the map gives the norm of the magnetic field for each position, and m = 3 when all three components of the magnetic field are tracked. The methods of representing the magnetic field tend to differ based on the size of p. Note that the works that tried to detect and mitigate perturbations in Earth's magnetic field did not create local magnetic field maps [4][5][6][7][8][9][10].…”

“…There are two opposing methods of using indoor magnetic fields in the literature. When the goal is to estimate attitude or heading using an indoor magnetic field, some works aim to remove or mitigate anomalies in the magnetic field [4][5][6] or reduce the impact of the magnetometer's effect on attitude estimates if disturbances are detected [7][8][9][10][11]. In this paradigm, Earth's magnetic field is seen as the signal, while any disturbances or anomalies are treated as noisy perturbations to be rejected.…”