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Front-crawl instantaneous velocity estimation using a wearable inertial measurement unit
Farzin Dadashi1, Florent Crettenand, Grégoire P Millet
1Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland. farzin.dadashi@epfl.ch
Sensors (Basel, Switzerland)
|December 4, 2012
Summary
This study introduces a new method using a single inertial measurement unit (IMU) to accurately estimate swimming velocity. This wearable technology offers coaches and scientists a practical tool for real-time performance feedback.
Area of Science:
- Sports Science
- Biomechanics
- Wearable Technology
Background:
- Performance monitoring is vital in elite sports, with velocity being a key metric in swimming.
- Current swimming performance evaluation methods are limited by the complexities of in-water measurements.
- Objective and practical tools are needed for accurate assessment of swimming velocity.
Purpose of the Study:
- To develop and validate a method for estimating front crawl swimming velocity using a single inertial measurement unit (IMU).
- To provide a practical and non-intrusive tool for monitoring swimming performance.
Main Methods:
- Thirty swimmers performed 25m trials at varying velocities, each equipped with an IMU placed on the sacrum.
- A tethered speedometer served as the reference for velocity measurement.
- Biomechanical constraints and a change detection framework were applied to IMU acceleration data for drift-free velocity estimation.
Main Results:
- The IMU-based method demonstrated a mean cycle velocity difference of 0.6 ± 5.4 cm·s⁻¹ compared to the reference.
- An RMS difference of 11.3 cm·s⁻¹ was observed for instantaneous velocity estimation.
- The study successfully validated the use of a single IMU for velocity estimation.
Conclusions:
- A single body-worn IMU can effectively estimate front crawl swimming velocity.
- This technology offers a practical, non-restrictive tool for objective swimming performance evaluation.
- Timely feedback is provided to coaches and sport scientists without complex setups or interference with technique.
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