9DoF Razor as 3D position tracker

I feel this topic is not exactly related to UAV's. But i am seriously working on ...

I am working on 3D position tracking in space.At first, i got my hands at 9DoF IMU from sparkfun as you all know well about this.

Many people tried making a tilt mouse using 3-Axis accelerometer by experiencing "linear motion" is difficult to get from accelerometer in 3D space ( since we can't move our hands in space exactly linear in x,y,z directions).

As you all know, the accelerometer gives acceleration = Gravity(causes tilt)+ Linear acceleration.

I want to remove the Gravity to get the Linear acceleration from the acceleration data.

And then i can use kalman filter to get the position from linear acceleration.

IMU writing instrument.pdf

The PDF file just gives brief idea how to get linear accelerations in 2D.

Is it possible to remove the gravity by sensing the tilt from accelerometer.

I appreciate equations are steps involved to do this.

Thanks

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Doug Weibel July 24, 2010 at 12:23pm

Harinath - I am afraid that this board will be completely worthless for the task you propose unless you only want a position estimate for a short time with poor accuracy. The accelerometers on this board are not high quality. The double integration will magnify all the error and your position estimate will diverge very quickly. I would expect a position estimate for any kind of a moving vehicle with modest vibration and vehicle dynamics to depart by meters (or more) in a matter of minutes.
Tom Yochum July 23, 2010 at 9:50am

You would need to use the gyros to sense the angular velocity. At that point you have built an inertial navigation system (INS).

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9DoF Razor as 3D position tracker

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