Patent ID: 7228252
Filing Date: 2007-06-05
Classification: G01D

Abstract:
1. A method of determining a drilling location on a wing skin, such that an attachment hole can be drilled through the wing skin and a supporting structure, the method comprising the steps of: (a) placing an object having an associated magnetic field on the supporting structure at the drilling location; (b) locating a position sensor on the wing skin, the position sensor comprising first and second magnetic field sensing devices, said first magnetic field sensing device located at a first position and the second magnetic field sensing device located at a second position, said second position different from said first position; (c) calibrating the first magnetic field sensing device, thereby deriving a first calibration; (d) calibrating the second magnetic field sensing device, thereby deriving a second calibration; (e) predicting the associated magnetic field using a mathematical model to obtain a predicted magnetic field; (f) sensing a first signal related to the magnetic field at the first position from the first magnetic field sensing device, and using the first calibration to derive a first measured magnetic field from the first signal; (g) sensing a second signal related to the magnetic field at the second position from the second magnetic field sensing device, and using the second calibration to derive a second measured magnetic field from the second signal; (h) comparing the predicted magnetic field with the first and second measured magnetic fields using an estimator algorithm, thereby calculating a most likely position of the object relative to the position sensor; (i) maneuvering the position sensor on the wing skin towards the calculated most likely position; (j) repeating steps (f) to (i) above, until the drilling location is determined; and (k) drilling said attachment hole at said drilling location.