How is distance calculated

[Peter]

Hi

I just wander, if anyone can give the science answer on how the distance is calculated in the Concept2.

I mean, different settings of fan, must give different distance calculations. But I don't se any measurement of the fan settings (1-10) ?

Regards
Peter

[Citroen]

I mean, different settings of fan, must give different distance calculations. But I don't see any measurement of the fan settings (1-10) ?

The flywheel sensor is simply a tachometer. it counts revolutions nothing more, nothing less. From that with a bit of computing you can calculate the speed (angular velocity), acceleration and deceleration. By analysing when the fan switches from accelerating to decelerating and back to accelerating you can determine when a new stroke starts.

The damper lever simply controls how much air flows through the fan, so with the damper fully open (10) that has the effect of slowing the acceleration on the drive and making it decelerate quicker on the recovery, nothing more, nothing less. There is no physical connection between the damper lever and the computer, sensing it is all done by analysing the tacho signal.

So from the simple tachometer input you can calculate a drag factor (that's the delta value on acceleration/deceleration of the fan). Compute a bit more maths and you'll arrive at the three primary output values provided to the rower. Those are time, strokes per min, distance. The watts, pace and calories are then derived from those three numbers.

http://www.atm.ox.ac.uk/rowing/physics/ergometer.html has more detail (from the days of the model B with a PM2).

http://www.concept2.co.uk/software/pmi.php gives you an ActiveX control that can be used to get lots of the data out of a PM3/PM4 into Excel (or other VB/ActiveX application) if you want to learn more about the science behind the rower. See http://www.concept2.co.uk/forum/viewtop ... =5&t=14482 for some discussion on that subject.

[Peter]

Thanks Citroen

Very informative. Now I understand.

Peter