96 G. Cazzulani et al. Fig. 10.3 Top view of the new handlebar of the rowing ergometer encoder equal to the one used for the seat. Moreover, the speed of the fan is acquired. This sensors allow collecting different useful indicators for the athlete training, summarising as: – The exact athlete power output, calculated multiplying the force on the handlebar and the first time derivative of the displacement; in this way, starting from this calculation, some other indicators can be obtained, such as the mean power of a rowing cicle, the global mean power and the maximum power; – The rowing frequency; – An estimation of the boat speed and covered distance, calculated starting from the fan speed. Figure 10.3 shows a picture of the modified handlebar. 10.5 The 3D Camera System The previous sections explain the work done to measure all the relevant quantities describing the dynamic interaction between the athlete and the rowing machine. However, in order to provide a complete training tool, those dynamic quantities may not be sufficient to fully describe the athlete behaviour during rowing. For this reason, the previously described measurement setup has been integrated with a 3D kinematic measurement of the athlete motion. All the kinematic joints of the athlete (ankles, knees, hip and so on) together with the moving parts of the rowing ergometer (the seat and the handlebar) are mapped with markers. Then, a set of six cameras is considered to measure the position of all the markers and to reconstruct the athlete motion during the rowing training. Figure 10.4 shows an example of the output of the 3D camera system. The black circles represent the position of the markers with respect to the global reference system. 10.6 Results and Discussion In this section, some experimental results obtained with the proposed instrumented rowing ergometer are shown. The results shown in Figs. 10.5 and 10.6 refer to a test of the female Italian rowing team member. In the test the athlete increases the rowing frequency from a minimum value of 22 strokes/min to a maximum value of 35 strokes/min. The test is performed with a footrest inclination equal to 45ı and without sliders between the rowing ergometer and the ground. Figure 10.5 shows the time histories of the complete test, while Fig. 10.6 shows the time history of a single rowing cicle.
RkJQdWJsaXNoZXIy MTMzNzEzMQ==