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Wireless kayak on-water ergometry - Part 1: Paddle blade force
KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). (Idrottsteknologi)
KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). (Idrottsteknologi)
KTH, School of Technology and Health (STH), Medical Engineering.
KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). Uppsala University, Uppsala, Sweden .
2013 (English)In: Sports Technology, ISSN 1934-6182, E-ISSN 1934-6190, Vol. 6, no 1, 29-42 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this work was to present a new wireless paddle force measurement system and to evaluate this measurement system. The system is redeveloped from a previous design and includes inertial motion sensors, which allows for the movement and inertia of the paddle to be taken into account. The system consists of two sensor nodes, designed for quick attachment to virtually any kayak paddle and an Android phone or tablet. Each sensor node measures the bending of the shaft in one plane. We derive the expressions necessary for computing the force on the paddle blade in two directions, ignoring the force in the direction of the shaft. Two different schemes for calibrating the system are presented. The accuracy and reliability of the system is evaluated in a laboratory setting using a material testing machine. An average error of 0.4% can be achieved for force measurements following directly after calibration. When the sensors are removed and reattached between calibration and measurements, average error between loading and measured force increased to 2.0% (linear model) and 1.8% (quadratic model). The limits of agreement depend on the position of the sensor nodes along the shaft and the feather angle if transverse sensitivity of the sensors is used to determine two-dimensional force on the paddle blade. On-water stroke force is presented, averaged over 10 strokes for each side with force levels >200 N to show the applicability of the study. The accuracy of the measurement is affected by the calibration method, placement of the paddle nodes and the shaft's properties.

Place, publisher, year, edition, pages
2013. Vol. 6, no 1, 29-42 p.
Keyword [en]
kayak, Kayak XL System, mobile phone, paddle, propulsive force, wireless measurement
National Category
Sport and Fitness Sciences Embedded Systems
URN: urn:nbn:se:kth:diva-101314DOI: 10.1080/19346182.2012.761707ScopusID: 2-s2.0-84893939955OAI: diva2:547052

QC 20140912. Updated from submitted to published.

Available from: 2012-08-27 Created: 2012-08-27 Last updated: 2014-09-12Bibliographically approved
In thesis
1. Wireless Multi-Sensor Feedback Systems for SportsPerformance Monitoring: Design and Development
Open this publication in new window or tab >>Wireless Multi-Sensor Feedback Systems for SportsPerformance Monitoring: Design and Development
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wireless applications have become a common part of daily life. Whether it is mobile phones, the Wi-Fi router at home, the keycard which has replaced the car key, a radio frequency identification access system to a building or a Bluetooth headset for your computer or phone, the means of modern wireless data exchange is an omnipresent technology. In sports, the market is in its infancy for wireless, technical applications or gadgets. Only heart rate monitors and GPS watches are currently used by recreational athletes. Even though most of the larger sports equipment companies regularly launch new products related to sports performance monitoring and mobile phone technology, product innovation leaps are rare.In this work the design of a wireless sports performance measurement platform is presented. Using the example of kayaking, this platform is configured as a paddle performance measuring system, the Kayak XL System, which can monitor propulsive paddle force, paddle kinematics and boat velocity, interalia. A common mobile phone platform has been chosen as the user interface for this system. The design approach focussing on user requests, demands and expectations in combination with the process of iterative technical development are unveiled in this thesis. An evaluation of the system is presented and the work is finalised with an overview of further systems which have been designed based on the developed measurement platform. The Kayak XL System is a flexible system designed to be mounted onto any standard kayak paddle and installed in any competition kayak. Versatility, unobtrusiveness and usability were major design concerns. The developed system consists of four modules plus a software which has been designed for Android mobile phones. The phone communicates with each of the four modules trough Bluetooth radio. These four modules are also referred to as nodes and have specific measurement purposes. Two nodes have been designed to measure paddle force and kinematics, one node has the purpose to measure foot stretcher force and boat motion data, and the fourth node enables a more convenient method of calibrating paddle force measurement. The fourth node is therefore only needed prior to performance data acquisition. Results show that paddle and foot stretcher force can be measured with a resolution below 1N after calibration. Installing the paddle nodes on a previously configured paddle without repeated calibration is facilitated with the compromise of a doubled error margin. The default sampling frequency is set to 100 Hz and can, like all system parameters, be configured on the mobile phone. Real-time computation of complex performance parameters is only limited by the phone CPU. The system adds twice 109 g to the paddle and approximately 850 g to the kayak, excluding the mass of the mobile phone

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xv, 89 p.
Trita-STH : report, ISSN 1653-3836 ; 2012:5
kayak, paddle, mobile phone, sports performance, propulsive force, boat velocity, sampling frequency, wireless measurement, wireless sensor, Kayak XL System, sensor piconet, sensor platform, user-centred design
National Category
Signal Processing Embedded Systems Medical Laboratory and Measurements Technologies Medical Equipment Engineering
urn:nbn:se:kth:diva-101159 (URN)978-91-7501-457-9 (ISBN)
Public defence
2012-09-14, Sal 3-211, Alfred Nobels Allé 10, Huddinge, 10:00 (English)

QC 20120827

Available from: 2012-08-27 Created: 2012-08-23 Last updated: 2012-08-28Bibliographically approved

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Sturm, DennisYousaf, KhurramBrodin, Lars-ÅkeHalvorsen, Kjartan
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Medical sensors, signals and systems (MSSS) (Closed 20130701)Medical Engineering
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