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View Full Version : [Question(s)] Dead reckoning using 9DOF IMU?



Freyzor
05-13-2014, 05:16 PM
Hi, I have a Pololu MinIMU v1 9DOF that I have working as a AHRS which is cool but would really like to to use it to estimate 3d motion as well. Do you folks know of functional Arduino (using Arbotix-M) examples that can do that or point me to good references on the subject?

I'm not really worried about drift over time atm but rather relative estimation over short distances as in "move 2 meters north".

jpieper
05-13-2014, 09:27 PM
The problem is not that the position drifts, but that the velocity drifts. So really, with no other sensors and no bias compensation, all you'll get is: "I'm moving 2m/s faster than I was 1s ago", which probably isn't that useful.

jwatte
05-13-2014, 10:52 PM
If you know when you're standing still (which you can as a rover or walker) then you can use that as "neutral calibration" and then integrate acceleration over time. With a flyer, not as much. I don't have example code, but it really is as simple as getting a reading, subtracting out neutral, multiplying by time, adding to velocity, and then multiplying velocity by time and adding to position. (If you want to be fancy, use an Runge-Kutta integrator or something.)
Main challenges include drift over time, vibration, and calibration (finding the exact relation between sensor readings and acceleration.)