Accellerometer spin

[joerg at openmoko.org]

Am So  18. Mai 2008 schrieb recursv at gmail.com:
> Instead of adding a compass to the device to be able to read spin about the 
> gravitational axis, would it not be easier to offset one of the 
> accellerometers from the centre of the device?   
> 
> That way, the roll is uneffected and the yaw and pitch can be calculated by 
> accounting for the known offset in the equ.  

With 2 g-meters you always have an axis through both of them. It's hard to 
distinguish rotation on this axis from linear acceleration also deviating the 
g-vector direction. Though linear acc. will inevitably change length of 
vector, whereas with rotation the g always stays with natural g of earth.

Anyway, to get somewhat exact real 3 axis rotation info even in deep space 
where no earth-g to be seen anymore, you need a set of gyros or at least 3 
g-meters mounted non-aligned and far from each other.

/jOERG