AVR-Chat

Hi,

a few years ago I built a little self leveling toy that used a solid 
state accelerometer from Maxim and a servo. My cruddy programming 
notwithstanding that sensor was quite capable of measuring angles for 
that particular application. A dual axis accelerometer setup 
perpendicular to Earth should have no trouble measuring absolute angles. 
There might even be an app-note on that subject.

	Sander

Rick wrote:
> 
> 
> --- In AVR-Chat@yahoogroups.com <mailto:AVR-Chat%40yahoogroups.com>, 
> "Richard" <richardt.bradshaw@...> wrote:
>  >
>  > Hi everybody I have been hanging around here for a while, great forum.
>  > Do any of you have any experience with accelerometers? I am thinking of
>  > a project using an accelerometer to measure angles. The idea is this:
>  > the accelerometer will be on the outer edge of a wheel. As the wheel is
>  > turned the position of the accelerometer will move then using a bit of
>  > grigonometry I can calculate the angle that it has moved through. My
>  > question is how much accuracy can I get. I will be looking to measure
>  > fractions of a degree on the wheel aprox 4 inches or 100mm in diameter.
>  > Doing the maths gives a movement of about .88mm/degree so I would like
>  > to be able to detect movement of about 0.2mm is this realistic?
>  > Cheers Rich
>  >
> 
> Accelerometers are typically dynamic "sensing devices". They sense
> "change" and are not a good choice for your electronic protractor
> device. A cheap way to go is to use a resistive potentiometer ( a
> simple POT ) with a weighted pendulum. A more sophisticated method of
> measuring the tilt angle you desire is to use an optical encoder who's
> shaft has a pendulum with a mass at the end. You could get "uber"
> fancy with gyroscopes and such, if you wanted to make a real science
> project out of it.
> 
> M5
> 
>