Permanent magnet

[jlinders32]

Hello i have a old simple rower that i want to make little smarter.
But it does work with a permanent magnet where you change the pull force by moving the steel plate closer to the magnet by a selector.
Is it possible to calibrate the flywheel inertia with that kind of construction?
I also read the Open rower monitor pages a couple times.
They have a algorithm that calculates the flywheel inertia/drag. I’m not sure but that will work maybe ?
Is that possible to on the ESP32 rowing monitor?

[Abasz]

Hi, thanks for taking interest in this project.

Is it possible to calibrate the flywheel inertia with that kind of construction?

Sure, it is. Actually your rower has a magnetic break which is fine, the principle is the same as for air rower only the break type is different. Inertia is not affected by this rather, the drag (your is magnetic). But drag is calculated by the algorithm.

They have a algorithm that calculates the flywheel inertia/drag. I’m not sure but that will work maybe ?

Actually this project is a port of ORM to some extend. The algorithm that is used by this project is quite close to the one that is used by ORM with some simplifications (that is due to resources on a Rpi vs ESP32). But generally this is not noticable.

important: Inertia is not calculated by the algorithm, that is an input setting (both in ORM and ESPRM no difference in this). So you should have your inertia (at least on a basis of a guess. Drag will be calculated automatically and all the metrics assuming you have set up stroke detection and other related settings.

Actually in a couple of month (may be sooner) I will release a new version, where all settings will be settable from the gui without recompilation so you would be able to tweak your settings from the official WEB Gui. Final version is currently under testing.

[JaapvanEkris]

Just a small addition from my side. ORM and ESP32 RowingMonitor share the core algorithms where possible. In practice, what ORM can do, ESP32 Rowing Monitor can do too, and typically need the same approach for determining the parameters.

Easiest approach for estimating inertia is to row on your machine with ESP32 Rowing Monitor, and adjust it until your pace makes sense. Comparing the feel and pace to a reliable machine (a Concept2 found in most gyms) is recommended but certainly not a requirement.

[jlinders32]

Thank you both for your fast responses and the input to setting up these projects.

But in my understanding if i adjust the dial to increase the magnetic field and i pull the handle with the same speed the flywheel has rpm will be the same just need more power to pull.
So on setting 3 i need less power to row 10km/h than on setting 6.
Possible that I don’t understand it right, it’s a lot to read and learn with a lot off variables.
Can’t imagine the amount of time you guys put into this project.

[JaapvanEkris]

But in my understanding if i adjust the dial to increase the magnetic field and i pull the handle with the same speed the flywheel has rpm will be the same just need more power to pull.

That is partially correct. It will indeed be affected more by the magnet. But ORM or ESPRM will measure this and automatically recalculate the drag for you. But your strokerate is also part of the equation: a higher drag can be compensated for by a higher strokerate.

So on setting 3 i need less power to row 10km/h than on setting 6.

Some manufacturers think that, but these are the incompetent ones so ignoring them is the best approach. Drag works as a gear: a higher drag (resistance) results in more distance per stroke. So the same work will result in the same distance.