Deep Learning for Inertial Sensor Alignment

TL;DR

This paper presents a deep learning approach to accurately estimate the yaw mounting angle of a smartphone with inertial sensors in a moving vehicle, improving real-time alignment without relying on GPS data.

Contribution

It introduces a data-driven neural network model that estimates the mounting angle using only inertial sensor data, trained with synthetic rotations, and validated in real-world scenarios.

Findings

Achieves 8-degree accuracy within 5 seconds

Achieves 4-degree accuracy within 27 seconds

Performs comparably to existing solutions in real-time

Abstract

Accurate alignment of a fixed mobile device equipped with inertial sensors inside a moving vehicle is important for navigation, activity recognition, and other applications. Accurate estimation of the device mounting angle is required to rotate the inertial measurement from the sensor frame to the moving platform frame to standardize measurements and improve the performance of the target task. In this work, a data-driven approach using deep neural networks (DNNs) is proposed to learn the yaw mounting angle of a smartphone equipped with an inertial measurement unit (IMU) and strapped to a car. The proposed model uses only the accelerometer and gyroscope readings from an IMU as input and, in contrast to existing solutions, does not require global position inputs from global navigation satellite systems (GNSS). To train the model in a supervised manner, IMU data is collected for training and validation with the sensor mounted at a known yaw mounting angle, and a range of ground truth labels is generated by applying a random rotation in a bounded range to the measurements. The trained model is tested on data with real rotations showing similar performance as with synthetic rotations. The trained model is deployed on an Android device and evaluated in real-time to test the accuracy of the estimated yaw mounting angle. The model is shown to find the mounting angle at an accuracy of 8 degrees within 5 seconds, and 4 degrees within 27 seconds. An experiment is conducted to compare the proposed model with an existing off-the-shelf solution.