These last few days I have worked on the calibration of the magnetic system. We want the calibration to be as easy as possible. By easy, I mean we will not have to measure precisely the position of the receiver to calibrate. The solution we have come up with is to fix the receiver on an optical table.We don’t know the position of the table nor its orientation.
Once the receiver is on the table ,we slide it several times by a known amount. s. At each position the measure the voltages in the receiver coilThese voltages are used to compute : the position of the optical table, its orientation, and the two calibration matrix.
These values are found using a gradient descent in Octave,but the result are not satisfactory yet. Octave stops the algorithm when the gradient is too low and I have not found yet how to prevent it. I get a ~5-10cm precision using the artificially noised measures (the measures are simulated) after calibration. I hope there won’t be too much noise on the real system.