AlexBaraba,
I'm assuming that
1. the accelerometers are mounted to the robot, and not a stabilized platform.
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2 You want to calculate the robot position with respect to the earth.
If this is the case, then you must calculate the direction of the robot after each iteration. Assume that the robot is initially pointed East, and we assume the intial position is zero. Let Ax, Ay be the forward and lateral accelerations. Then after the first iteration, the new East coordinate will be E=0 + .5Axt^2. The new North coordinate will be N=0 + .5Ayt^2. The new angle will be Theta =ATan(N/E). After the second iteration the new East coordinate is calculated by E = E + [.5Axt^2]Cos(Theta). The new North cordinate will be N = N + [.5Ayt^2]Sin(Theta). You would continue to calculate Theta, E, N for each succesive iteration.
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As a practical matter, this scheme works only if you have a way of updating the position periodically from an external source, since practical accelerometers always have biases that will result in the position calculations drifting with time.
Regards,
Kral