Get Handle Position via SDK

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Get Handle Position via SDK

Postby FooTheBar » April 1st, 2018, 6:42 am

Hey!

Is there a way to get the handle position with the SDK? I only found the force-curve, but I would love to also have the position. I'm thinking about measuring the seat-position with an additional sensor and compare both positions to check if the user e.g. is shooting the slide.
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Re: Get Handle Position via SDK

Postby Citroen » April 1st, 2018, 8:19 am

There isn't. The monitor only measures one thing from the handle, chain and flywheel. That's the angular velocity of the three magnets on the flywheel.

Everything else is calculated from that simple measurement.

The force curve gives you a good clue when the stroke starts versus when it ends and the recovery begins - you can deduce the handle position from that (in relative terms).

I can't see what you'd get by measuring the seat position since you won't know for sure where the handle is. It's much easier to use a video recording to show a rower who's shooting the slide.
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Re: Get Handle Position via SDK

Postby FooTheBar » April 1st, 2018, 8:37 am

Thanks! I don't yet understand how the force can be computed from these sensors. The magnets should give me position updates for the flywheel so I can compute an (angular) velocity or acceleration. But the force depends on both the acceleration and damper settings, so how are these settings measured?

Why do you think that the seat position wouldn't help? If I see that the handle is moving for several cm but the seat is still stationary, I know that the user doesn't have a good connection. And also at the start of the recovery, the handle should show significant movement to the front before the slide should start to move.
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Re: Get Handle Position via SDK

Postby Citroen » April 1st, 2018, 9:27 am

They know the mass of the flywheel, they're getting a tacho signal from the sensor. The maths is complex but not impossible.

http://eodg.atm.ox.ac.uk/user/dudhia/ro ... meter.html
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Re: Get Handle Position via SDK

Postby FooTheBar » April 1st, 2018, 9:38 am

They measure the drag factor during recovery while there is no additional force from the rower. Neat trick...
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