Publications by Julien Chardonnens

Joint Inertial Sensor Orientation Drift Reduction for Highly Dynamic Movements

Kamiar Aminian, Julien Chardonnens, Benedikt Fasel

Inertial sensor drift is usually corrected on a single-sensor unit level. When multiple sensor units are used, mutual information from different units can be exploited for drift correction. This study introduces a method for a drift-reduced estimation of t ...

2018

Three-Dimensional Body and Centre of Mass Kinematics in Alpine Ski Racing Using Differential GNSS and Inertial Sensors

Kamiar Aminian, Julien Chardonnens, Benedikt Fasel, Geo Boffi

A key point in human movement analysis is measuring the trajectory of a person’s center of mass (CoM). For outdoor applications, differential Global Navigation Satellite Systems (GNSS) can be used for tracking persons since they allow measuring the traject ...

MDPI2016

Determination of the centre of mass kinematics in alpine skiing using differential global navigation satellite systems

Julien Chardonnens

In the sport of alpine skiing, knowledge about the centre of mass (CoM) kinematics (i.e. position, velocity and acceleration) is essential to better understand both performance and injury. This study proposes a global navigation satellite system (GNSS)-bas ...

Taylor & Francis2015

An inertial sensor-based system for spatio-temporal analysis in classic cross-country skiing diagonal technique

Kamiar Aminian, Julien Favre, Julien Chardonnens, Benedikt Fasel

The present study proposes a method based on ski fixed inertial sensors to automatically compute spatio-temporal parameters (phase durations, cycle speed and cycle length) for the diagonal stride in classical cross-country skiing. The proposed system was v ...

Elsevier2015

Measurement of the dynamics in ski jumping using a wearable inertial sensor-based system

Kamiar Aminian, Julien Favre, Julien Chardonnens

Dynamics is a central aspect of ski jumping, particularly during take-off and stable flight. Currently, measurement systems able to measure ski jumping dynamics (e.g., 3D cameras, force plates) are complex and only available in few research centres worldwi ...

Taylor & Francis2014

Suitability of commercial barometric pressure sensors to distinguish sitting and standing activities for wearable monitoring

Kamiar Aminian, Anisoara Ionescu, Julien Chardonnens, Fabien Massé, Alan Kevin Bourke

Despite its medical relevance, accurate recognition of sedentary (sitting and lying) and dynamic activities (e.g. standing and walking) remains challenging using a single wearable device. Currently, trunk-worn wearable systems can differentiate sitting fro ...

Elsevier2014

A wearable system to measure speed and phase durations during each cycle of classical cross-country skiing

Kamiar Aminian, Julien Favre, Julien Chardonnens, Benedikt Fasel

2013

A system to measure the kinematics during the entire ski jump sequence using inertial sensors

Kamiar Aminian, Julien Favre, Julien Chardonnens

Three-dimensional analysis of the entire sequence in ski jumping is recommended when studying the kinematics or evaluating performance. Camera-based systems which allow three-dimensional kinematics measurement are complex to set-up and require extensive po ...

Elsevier2013

Determination of External Forces in Alpine Skiing Using a Differential Global Navigation Satellite System

Julien Chardonnens

In alpine ski racing the relationships between skier kinetics and kinematics and their effect on performance and injury-related aspects are not well understood. There is currently no validated system to determine all external forces simultaneously acting o ...

Mdpi Ag2013

3D measurement of lower limb kinematics in alpine ski racing using inertial sensors

Kamiar Aminian, Julien Chardonnens, Benedikt Fasel

2013

Distinguishing Sitting and Standing Activities Using a Wearable Barometric Pressure Monitor

Kamiar Aminian, Anisoara Ionescu, Julien Chardonnens, Fabien Massé, Alan Kevin Bourke

Recent advancements in wearable inertial sensor technology have enabled extensive research into activity classification. However, the distinction between the sitting and standing activities using trunk-worn wearable monitoring systems remains challenging, ...

2013

Automatic measurement of key ski jumping phases and temporal events with a wearable system

Kamiar Aminian, Julien Favre, Benoît Le Callennec, Julien Chardonnens

We propose a new method, based on inertial sensors, to automatically measure at high frequency the durations of the main phases of ski jumping (i.e. take-off release, take-off, and early flight). The kinematics of the ski jumping movement were recorded by ...

Taylor & Francis2012

In-field objective evaluation and analysis in ski jumping using inertial sensors

Julien Chardonnens

Ski jumping, a prestigious Olympic discipline, has been constantly evolving. Over the years, the biomechanics fundamentals of this highly technical sport have been intensively documented by investigating the jump timing, kinematics, dynamics and motor cont ...

EPFL2012

An effortless procedure to align the local frame of an inertial measurement unit to the local frame of another motion capture system

Kamiar Aminian, Julien Favre, Julien Chardonnens

Inertial measurement units (IMUs) offer great opportunities to analyze segmental and joints kinematics. When combined with another motion capture system (MCS), for example, to validate new IMU-based applications or to develop mixed systems, it is necessary ...

Elsevier2012

Analysis of inter-segment coordination during the take-off of ski jumping

Kamiar Aminian, Julien Favre, Julien Chardonnens

In ski jumping, take-off (TO) is considered as the most important phase. While spatio-temporal features have been identified during this phase, inter-segment coordination has never been investigated. This study proposed a new method using body worn inertia ...

2011

A new method for unconstrained measurement of knee joint angle and timing in alpine skiing : Comparison of crossover and crossunder turns

Kamiar Aminian, Julien Favre, Julien Chardonnens

Timing is an important part in the analysis of alpine skiing technique. Key events extracted from dynamics and kinematics of ski were previously proposed, but timing of body segments kinematics is also required to understand the biomechanics and to assess ...

2010

Orientation of body segments in ski jumps using wearable sensors: Analysis of relevant parameters during stable flight phase

Kamiar Aminian, Julien Favre, Julien Chardonnens

Biomechanics analysis of the ski jump is highly required. Some parameters and their interrelations have been reported in previous research studies limited to few athletes. The generalization of these parameters to athletes of various levels and under train ...

2010

Knee joint kinematics measurement in alpine skiing based on inertial sensors

Kamiar Aminian, Julien Favre, Julien Chardonnens

2010

A new wearable system assessing the main relevant metrics of the whole ski jumping sequence

Kamiar Aminian, Julien Favre, Julien Chardonnens

2010

Orientation of body segments in ski jumps using wearable sensors: Analysis of relevant parameters during stable flight phase

Kamiar Aminian, Julien Favre, Julien Chardonnens

3D kinematic and dynamic analysis is highly required in ski jumping. Current recording techniques (e.g. camera systems) suffered from limitations, such as volume capture or complexity of use and processing. This study proposed a new 3D approach based on in ...

2010