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Natural locomotion based on a reduced set of inertial sensors: decoupling body and head directions indoors

Bergamini, Elena; de la Rubia, Ernesto; Diaz-Estrella, Antonio; Reyes-Lecuona, Arcadio; Langley, Alyson; Brown, Michael; Sharples, Sarah


Elena Bergamini

Ernesto de la Rubia

Antonio Diaz-Estrella

Arcadio Reyes-Lecuona

Alyson Langley

Michael Brown


Inertial sensors offer the potential for integration into wireless virtual reality systems that allow the users to walk freely through virtual environments. However, owing to drift errors, inertial sensors cannot accurately estimate head and body orientations in the long run, and when walking indoors, this error cannot be corrected by magnetometers, due to the magnetic field distortion created by ferromagnetic materials present in buildings. This paper proposes a technique, called EHBD (Equalization of Head and Body Directions), to address this problem using two head- and shoulder-located magnetometers. Due to their proximity, their distortions are assumed to be similar and the magnetometer measurements are used to detect when the user is looking straight forward. Then, the system corrects the discrepancies between the estimated directions of the head and the shoulder, which are provided by gyroscopes and consequently are affected by drift errors. An experiment is conducted to evaluate the performance of this technique in two tasks (navigation and navigation plus exploration) and using two different locomotion techniques: (1) gaze-directed mode (GD) in which the walking direction is forced to be the same as the head direction, and (2) decoupled direction mode (DD) in which the walking direction can be different from the viewing direction. The obtained results show that both locomotion modes show similar matching of the target path during the navigation task, while DD’s path matches the target path more closely than GD in the navigation plus exploration task. These results validate the EHBD technique especially when allowing different walking and viewing directions in the navigation plus exploration tasks, as expected. While the proposed method does not reach the accuracy of optical tracking (ideal case), it is an acceptable and satisfactory solution for users and is much more compact, portable and economical,


Bergamini, E., de la Rubia, E., Diaz-Estrella, A., Reyes-Lecuona, A., Langley, A., Brown, M., & Sharples, S. (2018). Natural locomotion based on a reduced set of inertial sensors: decoupling body and head directions indoors. PLoS ONE, 13(4), Article e0195191.

Journal Article Type Article
Acceptance Date Mar 4, 2018
Publication Date Apr 1, 2018
Deposit Date Apr 16, 2018
Publicly Available Date Apr 16, 2018
Journal PLoS ONE
Electronic ISSN 1932-6203
Publisher Public Library of Science
Peer Reviewed Peer Reviewed
Volume 13
Issue 4
Article Number e0195191
Public URL
Publisher URL


journal.pone.0195191.pdf (21.4 Mb)

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