hamster ergometry
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Posts: 46,084
Jack,
To measure the wheel, I'm using a bicycle speed sensor (reed switch),
using COUNT on the BS2 (count number of revs per interval--3-5 seconds?).
I can measure angular speed and get energy (hence frictional force
and/or power out) from KE = 1/2 I w^2, but I want some way to measure
energy *directly* instead of per calculation with a measured quantity
like w.
Actually, I want to do it both ways so that I can compare ...
Will keep all abreast ...
Michael
--- In basicstamps@yahoogroups.com, goflo@p... wrote:
> Schemes...
>
> Arrange for the wheel rungs to interrupt a light beam,
> measure & record the intervals - PULSIN? ...
>
> Say the hamster is imparting momentum to the wheel 5 times
> per second, the rest of the time the wheel is decelerating.
>
> An estimate of this constant deceleration should be possible
> by inspecting the data, so knowing rpm & the mass of the wheel,
>
> power = (mass in lbs) X (accel in G) X (velocity in fps)
>
> Or perhaps the polar moment of inertia of the wheel could be
> found - Power could then be derived from the observed acceler-
> ations.
>
> However you do it, I'd like to hear about it.
>
> regards, Jack
>
> webbm03 wrote:
> >
> > As an aside to the project, I intend to estimate the power output of
> > the hamster as he runs at various speeds. The physicist in me just
> > can't resist.
> >
> > I plan to do some simple measurements of "spin-down" times beginning
> > with various wheel speeds, and estimate the speed-dependent (I assume)
> > friction in the wheel. Of course, this will be only the work that
> > hamster's doing on the wheel, which doesn't include the work he's
> > doing within his body to run. Nevertheless, it will give us an
> > estimate of how much "external" work he can do.
> >
> > Does anybody out there know of another way to measure power on such a
> > small scale? Measuring "spin-down" times may be somewhat
inaccurate ...
To measure the wheel, I'm using a bicycle speed sensor (reed switch),
using COUNT on the BS2 (count number of revs per interval--3-5 seconds?).
I can measure angular speed and get energy (hence frictional force
and/or power out) from KE = 1/2 I w^2, but I want some way to measure
energy *directly* instead of per calculation with a measured quantity
like w.
Actually, I want to do it both ways so that I can compare ...
Will keep all abreast ...
Michael
--- In basicstamps@yahoogroups.com, goflo@p... wrote:
> Schemes...
>
> Arrange for the wheel rungs to interrupt a light beam,
> measure & record the intervals - PULSIN? ...
>
> Say the hamster is imparting momentum to the wheel 5 times
> per second, the rest of the time the wheel is decelerating.
>
> An estimate of this constant deceleration should be possible
> by inspecting the data, so knowing rpm & the mass of the wheel,
>
> power = (mass in lbs) X (accel in G) X (velocity in fps)
>
> Or perhaps the polar moment of inertia of the wheel could be
> found - Power could then be derived from the observed acceler-
> ations.
>
> However you do it, I'd like to hear about it.
>
> regards, Jack
>
> webbm03 wrote:
> >
> > As an aside to the project, I intend to estimate the power output of
> > the hamster as he runs at various speeds. The physicist in me just
> > can't resist.
> >
> > I plan to do some simple measurements of "spin-down" times beginning
> > with various wheel speeds, and estimate the speed-dependent (I assume)
> > friction in the wheel. Of course, this will be only the work that
> > hamster's doing on the wheel, which doesn't include the work he's
> > doing within his body to run. Nevertheless, it will give us an
> > estimate of how much "external" work he can do.
> >
> > Does anybody out there know of another way to measure power on such a
> > small scale? Measuring "spin-down" times may be somewhat
inaccurate ...
Comments
Arrange for the wheel rungs to interrupt a light beam,
measure & record the intervals - PULSIN? ...
Say the hamster is imparting momentum to the wheel 5 times
per second, the rest of the time the wheel is decelerating.
An estimate of this constant deceleration should be possible
by inspecting the data, so knowing rpm & the mass of the wheel,
power = (mass in lbs) X (accel in G) X (velocity in fps)
Or perhaps the polar moment of inertia of the wheel could be
found - Power could then be derived from the observed acceler-
ations.
However you do it, I'd like to hear about it.
regards, Jack
webbm03 wrote:
>
> As an aside to the project, I intend to estimate the power output of
> the hamster as he runs at various speeds. The physicist in me just
> can't resist.
>
> I plan to do some simple measurements of "spin-down" times beginning
> with various wheel speeds, and estimate the speed-dependent (I assume)
> friction in the wheel. Of course, this will be only the work that
> hamster's doing on the wheel, which doesn't include the work he's
> doing within his body to run. Nevertheless, it will give us an
> estimate of how much "external" work he can do.
>
> Does anybody out there know of another way to measure power on such a
> small scale? Measuring "spin-down" times may be somewhat inaccurate ...
along the lines of a drag-cup speedometer. Axle spins
a small copper disc - A magnetic field will excite an
eddy current in the disc, and an opposing torque in the
magnet, which could be resolved into an angular component.
Jack
webbm03 wrote:
>
> Jack,
>
> To measure the wheel, I'm using a bicycle speed sensor (reed switch),
> using COUNT on the BS2 (count number of revs per interval--3-5 seconds?).
>
> I can measure angular speed and get energy (hence frictional force
> and/or power out) from KE = 1/2 I w^2, but I want some way to measure
> energy *directly* instead of per calculation with a measured quantity
> like w.
>
> Actually, I want to do it both ways so that I can compare ...