Elsevier

Journal of Biomechanics

Volume 43, Issue 4, 3 March 2010, Pages 767-770
Journal of Biomechanics

Short communication
Dynamic force measurements for a high bar using 3D motion capturing

https://doi.org/10.1016/j.jbiomech.2009.10.035Get rights and content

Abstract

The displacement of a calibrated horizontal bar is used as a measure for forces acting on the bar itself during dynamic performances in artistic gymnastics. The high bar is loaded with known forces and the displacement is monitored by means of a Vicon motion capturing system. The calibration results are fitted according to the Euler–Bernoulli beam theory. After calibration, forces can straightforwardly be measured by multiplication of the bar displacement with the determined fit parameter. This approach is also able to account for non-central force application (two hands on the bar) and the effect of the bar's inertia. Uncertainties in measured forces are assessed to be ±25N plus an additional 1% for the unknown weight distribution between the two hands.

Introduction

Measurement and knowledge of time-dependent forces acting on the athlete during performances on the high bar are of high relevance for better understanding of an athlete's physical requirements and abilities as well as for studying, modeling, and optimizing different exercises. Different studies aimed to model and optimize such gymnastic movements on the horizontal bar (Hiley and Yeadon, 2005, Hiley and Yeadon, 2008), others tried to describe the energetic processes during different exercises (Arampatzis and Brüggemann, 1999, Arampatzis and Brüggemann, 2001), but little information about forces during such high bar performances is available in the literature. Force measurements from bar mounted strain gauges were presented in Arampatzis and Brüggemann (1999). There, two different systems (at different framing rates) have been used to record the strain gauge readings and video data. The new approach presented within this work uses only one single system for all measurements, which eliminates such synchronization related errors as described in Lipfert et al. (2009).

The aim of this study was to deploy a Vicon 3D motion capturing system not only for tracking and analysis of an athlete's performance on the high bar but also for dynamic force measurements of that same exercise. Tests indicated that the spatial resolution of a Vicon system is sufficient to detect the bar displacement with a precision and accuracy needed to use the bar itself as a dynamometer. This approach only needs one system to be set up and further facilitates data evaluation as all data is recorded with the same system and renders subsequent data synchronizations unnecessary. Additionally, the effect of the high bar's inertia can be addressed since forces, displacement vectors, and derivatives thereof are available.

Section snippets

Methods

A FIG conform horizontal bar (Fédération Internationale de Gymnastique—Apparatus Commission, 2006) was set-up and centered within a Vicon V612 motion capturing system (Oxford Metrics Ltd, UK) with 8 M2 near-infrared cameras operating at 100 Hz. The (Cartesian) coordinate origin was set in the center-of-mass of the horizontal bar itself. The calibrated 3D volume covered 3 m in x-direction (axis through bar), 5.5 m in z-direction (height), and 6 m in y-direction (length). For the purpose of bar

Results

The calibration coefficients at the origin for the three studied tensions are listed in Table 1. A continuous trend towards smaller ratios of the calibration coefficients in y- and z-direction, ky/kz, with increasing stiffness of the tension cables is observed. Unsurprisingly, higher tensions at the cables do have a larger influence on the y as on the z-direction (additional contribution from bar supports). To calculate the displacement for any other position along the bar further information

Discussion

We have developed a dynamic method to use the displacement of a horizontal bar to measure the forces acting on the bar by means of a motion capturing system. The main advantage of this approach is the dual use of the same equipment for both, motion analysis of exercises on the high bar and simultaneous force measurements thereof. Once the initial calibration has been performed the main measurement is easily performed together with the motion capturing. The same data evaluation procedures as for

Conflict of interest statement

None declared.

Acknowledgments

The authors would like to acknowledge the help of Alfred Fürhapter-Rieger and Patrick Rosmann during setup and data acquisition.

References (9)

There are more references available in the full text version of this article.

Cited by (11)

  • Occlusion trajectory and a concept of a device for testing operating life of dentures

    2016, Advances in Medical Sciences
    Citation Excerpt :

    For the purpose of the tests, a non-invasive system for a comprehensive movement analysis was used, i.e. SMART by BTS. Systems of this type are used for tasks such as: analysis of human walking [9], recognition of human emotions [10], animation of human movement [11], robotics [12], or sports [13]. Possibilities of this type of systems are not limited only to the movements performed within the frame of large joints of the human body.

  • Shoulder muscles recruitment during a power backward giant swing on high bar: A wavelet-EMG-analysis

    2012, Human Movement Science
    Citation Excerpt :

    Between 270° and 360° (or until bar release) of the PBGS, the angular acceleration, the total body energy was increasing while the moment of inertia was decreasing (Fig. 1). This result was consistent with previous results which determined that the deflection of the high bar (Brüggemann, Cheetham, Alp, & Arampatzis, 1994; Cagran et al., 2010) and the tensile load on the bar (Arampatzis & Brüggemann, 1998; Cagran et al., 2010; Holvoet et al., 2002) were the highest in that part of the PBGS. At around the lowest point (≈270°), the shoulders were hyper-extended (Yeadon & Hiley, 2000) in order to set the tension of the extensor chain muscles of the humerus and prepare the shoulder flexion during the ascending part.

  • Development a simulation model for dynamic analysis of high bar dismounts

    2019, 2019 Scientific Meeting on Electrical-Electronics and Biomedical Engineering and Computer Science, EBBT 2019
  • Power estimation of martial arts movement with different physical, mood, and behavior using motion capture camera

    2017, Proceedings of SPIE - The International Society for Optical Engineering
  • Power estimation of martial arts movement using 3D motion capture camera

    2017, Proceedings of SPIE - The International Society for Optical Engineering
View all citing articles on Scopus
View full text