[LAU] A crazy idea

[fons at kokkinizita.net]

On Thu, Mar 04, 2010 at 10:00:09PM +0100, Nick Copeland wrote:
 
> > > > Nick Copeland suggested simulating the force applied to the pedals by 
> > > > calculating the rate of change of the cadence. I reckon that might do 
> > > > the trick.
> > > 
> > > It doesn't. Just consider going uphill 5% or downhill 5% at
> > > the same and constant cadence. Makes some difference to your
> > > legs and to a motor.
> > 
> > Well, then you need an accelerometer [1]. [2] is said to be in the 
> > iPhone, but you probably want something easier to solder.
> > 
> > With it you could get the inclination angle and then get the applied
> > force. If you do it right you could even get a crashing sound when
> > falling...
> 
> Actually it does do the trick, Fons doesn't understand the british turn of 
> phrase: Jon is not implying an attempt to win the 2010 Tour de France
> with his contraption, he is going to have fun on the way to work so I am sure
> he can extract acceleration (from traffic lights, Fons, he doesn't actually want 
> to be the King of the Mountains or anything, not even give or take 5%) based 
> on the rate of change of a signal.

With such noise generating things on your bike you'd be
excluded from the TDF anyway :-)

Of course you can find acceleration from the rate of change
of cadence plus gear ratio etc. And according to Newton,
F = ma and we know m. But that assumes that it is the force
on the pedals that causes the acceleration, which is not
always the case. And the roar of a motor is very dependent
on the work it has to do.

For the simulations I've been working on (Italian cars,
fast, usually red, I can't say more), we used RPM and 
throttle position as the inputs to the motor model.
RPM defines the fundamental frequency, but the power
delivered by the moter defines the spectrum.

Ciao, 

-- 
FA

O tu, che porte, correndo si ?
E guerra e morte !