Foot progression angle estimation using a single foot-worn inertial sensor

Frank J. Wouda*, Stephan L.J.O. Jaspar, Jaap Harlaar, Bert-Jan F. van Beijnum, Peter H. Veltink

*Corresponding author for this work

Research output: Contribution to journalArticleAcademic

13 Citations (Scopus)
115 Downloads (Pure)


Background: The foot progression angle is an important measure used to help patients reduce their knee adduction moment. Current measurement systems are either lab-bounded or do not function in all environments (e.g., magnetically distorted). This work proposes a novel approach to estimate foot progression angle using a single foot-worn inertial sensor (accelerometer and gyroscope).

Methods: The approach uses a dynamic step frame that is recalculated for the stance phase of each step to calculate the foot trajectory relative to that frame, to minimize effects of drift and to eliminate the need for a magnetometer. The foot progression angle (FPA) is then calculated as the angle between walking direction and the dynamic step frame. This approach was validated by gait measurements with five subjects walking with three gait types (normal, toe-in and toe-out).

Results: The FPA was estimated with a maximum mean error of ~ 2.6° over all gait conditions. Additionally, the proposed inertial approach can significantly differentiate between the three different gait types.

Conclusion: The proposed approach can effectively estimate differences in FPA without requiring a heading reference (magnetometer). This work enables feedback applications on FPA for patients with gait disorders that function in any environment, i.e. outside of a gait lab or in magnetically distorted environments.

Original languageEnglish
Article number37
JournalJournal of neuroengineering and rehabilitation
Issue number1
Publication statusPublished - 17 Feb 2021


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