Calculating Tilt from Accelerometer

[llienossor]

Hi,

I'm using a ADXL311 acceleromoter as a Tilt Sensor. The equations
given to calculate the tilt on the x axis or Pitch is ASIN(Ax/1g) and
the tilt on the y axis or Roll is ASIN(Ay/1g). g is acceleration due
to gravity, Ax & Ay are the amplitudes of the analog voltages from x
and y outputs. But I do not know what the A (presumabely amplitude of
some sort) before SIN represents.

If anyone has any ideas I would be very grateful.

Thanks.

llienossor

 

[Tim Shoppa]

But I do not know what the A (presumabely amplitude of
some sort)
before SIN represents.
arcsin, the functional inverse of the sine function.

Tim.

 

[Tim Wescott]

Tim Shoppa wrote:

But I do not know what the A (presumabely amplitude of

some sort)

before SIN represents.

arcsin, the functional inverse of the sine function.

Tim.

and the 'Ax', 'Ay' are the accelerations, not the voltages. Arcsine

takes a dimensionless parameter and coughs one up. If you're taking the
arcsine of something with mismatched dimensions you know you're doing
something wrong.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Rene Tschaggelar]

llienossor wrote:

Hi,

I'm using a ADXL311 acceleromoter as a Tilt Sensor. The equations
given to calculate the tilt on the x axis or Pitch is ASIN(Ax/1g) and
the tilt on the y axis or Roll is ASIN(Ay/1g). g is acceleration due
to gravity, Ax & Ay are the amplitudes of the analog voltages from x
and y outputs. But I do not know what the A (presumabely amplitude of
some sort) before SIN represents.

If anyone has any ideas I would be very grateful.

Have a look at the datasheets, the application notes and
some trigonometry.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net