On Mon, Aug 01, 2005 at 08:55:53AM -0400, linux-os (Dick Johnson) wrote: > > Jan Engelhardt wrote: > >>> So in order to calibrate it you need a readily available source of > >>> constant acceleration, preferably with a known value. > >>> > >>> Hint: -9.8 m/sec^2. > >> > >> Drop it out of the window? :) > > > > No, no. Constant gravity (like having the laptop sitting on the desk) > > "feels like" constant acceleration. > > > > Dropping it out of the window should measure 0 m/sec^2, because the > > accelerometer is not working on an inertial referential (I hope this is > > the correct term in english...). For the accelerometer, this is just > > like the feeling of free falling inside an elevator: no gravity :) > > > > -- > > Paulo Marques - www.grupopie.com > > You need a centrifuge or something that works like one. You can > make one and you can calibrate it using simple techniques.
Not at all. It's enough to let the laptop lie on the table for [0,0]G calibration, then put sequentially it on all the four sides for [-1,0]G, [1,0]G, [0,1]G, [0,-1]G calibration. >From these five measurements you have both the zero point and the slopes, including a good error estimate. I've done that before when toying with IMUs. -- Vojtech Pavlik SuSE Labs, SuSE CR - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/