0
\$\begingroup\$

I want to sense 3D motion (gesture). I have 3 axis accelerometer. But I am confused if I need a gyroscope or not for orientation and rotation sensing.

  1. Isn't it possible to measure them from accelerometer alone? Because when the sensor rotates along one axis (say z-axis), there will be change in y-axis and x-axis output in accelerometer.

  2. Is gyroscope really necessary or is it just easier if I have one?

\$\endgroup\$
1
\$\begingroup\$

Consider an accelerometer experiencing a net acceleration of gx - gz.

There are an infinite possible ways to achieve this, here are few examples:

  1. The sensor is oriented with z pointing towards the sky, and the user is moving it laterally relative to the ground with acceleration g.
  2. The sensor is oriented x pointing towards the ground, and the user is moving it laterally relative to the ground with acceleration -g.
  3. The sensor x/z plane is oriented at a 45 degree angle, and the user is moving it in a down-ward/left direction.
  4. The sensor is rotating about some point, moving with a non-constant velocity such that the acceleration is gx - gz.

etc.

So a single accelerometer cannot determine its orientation if it's experiencing acceleration and gravity.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.