[Paul Copioli]

I want to take this opportunity to warn everyone considering using an accelerometer to pay attention to gravity. An accelerometer measures all acceleration, even the acceleration due to gravity. How level the playing field is and how level the robot is will definitely change your accelerometer readings. You must compensate for gravity when using these devices.

At FANUC Robotics, we use 3 axis accelerometers and constantly perform coordinate transformations to always know which way our accelerometer axes are facing wrt gravity. Many of you will notice "drift" when trying out your accelerometers. This "drift" is most likely due to a non-level surface and gravity coming into play.

I just thought you should know.