94 G. Cazzulani et al. Anyway, as previously pointed out, all these studies focus only on some aspects of the rowing mechanics, without providing a full information about the rowing kinematics and dynamics and about the athlete-machine interaction. This paper presents the work done to fully instrument a commercial rowing ergometer called “Concept 2” in order to directly measure all relevant quantities for improved training and rowing optimization: the seat, the handlebar and the stretcher have been re-designed and equipped with force and displacement sensors able to measure both the dynamic and kinematic behaviour of the athlete. In detail: – Two displacement sensors mounted on the seat and on the handlebar, together with a 3D camera system allow measuring the motion of both the athlete and the moving parts of the rowing ergometer (the seat and the handlebar); – Four single axis load cells under the seat allow measuring the normal load on the seat as well as the longitudinal and lateral position of the application point of this normal load; – Five single axis load cells between the stretchers and the structure of the rowing ergometer allow measuring the normal and longitudinal load applied by the athlete on the stretcher as well as the longitudinal and lateral position of the application point of this normal load; – One single axis load cell at the handlebar allows measuring the applied force. In this way the interaction of the athlete with the rowing machine is fully known, together with the direct measurement of the instantaneous rowing power output. In the following, the first three sections describes the project of the re-designed stretcher, seat and handlebar respectively and the corresponding measurement layout. Section 10.5 describes the 3D camera system that measures the athlete’s motion. Finally, in Sect. 10.6 some results are presented and discussed. 10.2 The Stretcher Boat stretchers (or footrests) are typically designed in order to optimize the rowing performance: the stretcher inclination can be adjusted in order to adapt it to the athlete’s ergonometric characteristics and the feet are kept as close as possible one to the other in order to reduce the boat width and, as a consequence, the drag force on it. On the contrary, the stretcher inclination of Concept 2 ergometer is fixed. Moreover, the distance between the feet is greater than that on the boat due to the presence of the supporting structure between them. For this reason, the ergometer stretcher has been completely re-designed, in order to make it as similar as possible to the one mounted on boats. The footrest inclination can now be adjusted from a 38ı angle to a 52ı angle with respect to the ground. Figure 10.1 shows the design of the new proposed stretcher. The stretcher is equipped with five single-axis force sensors in order to measure the longitudinal and vertical force applied by the athlete. The load cells are inserted into the rods connecting the footrest and the chassis. In this way, they sense only an axial force and the measurement is not affected by moments or shear forces. In detail, one load cell measures the longitudinal force, while the remaining 4 ones measure the vertical forces. Due to the symmetry of the ergometer rowing, the lateral force is assumed negligible and not measured. Fig. 10.1 The re-designed stretcher for concept 2 ergometer
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