Question
1. I'm considering designing a sensor that contains a 3 axis MEMS accelerometer
with a range
of ±2g. The Z axis acceleration will reach 50-100g during most of the
measurements.
Will the Z axis clipping affect the X and Y axes measurements of the
accelerometer?
2. Is it better to use a two axis MEMS device for the X,Y axis (range ±2g) and
a
separate one axis MEMS device (range ±100g) for the Z axis?
Answer
1. The ADXL335, for example, uses a single structure for sensing the X, Y, and
Z axes. As a
result, the three axes sense directions are highly orthogonal with little cross
axis sensitivity (specified typical +/-1%). In your case, the cross axis
sensitivity from the Z axis will most likely affect the X and Y axes
measurements significantly, due to the acceleration ranges differing by a
potential factor of 50.
2. Considering the g range on the Z axis can be up to 50 times larger than on
the X
and Y axes, it would be better to opt for a 2 axis ±2g accelerometer for the X
and Y axes, and a single axis ±100g accelerometer for the Z axis.