Method and apparatus for locating non-visible objects

摘要

Non-visible objects which differ in their physical properties from their surroundings by association with a variable strength magnetic field may be detected by a suitable array of sensors which can be moved relative to the object in question. By analyzing the signals from the plurality of the sensors in the array, the position of the object can be deduced relative to the array and the array moved to enable a machining guide thereon to be aligned with the non-visible object. The system is of particular value in locating apertures in wing spars when attempting to fix the skin of the wing on to them where it is important to be able to locate the correct point at which to drill a hole through the skin to coincide with the hole in the spar. By defining a magnetic field in the vicinity of the hole to identify the hole magnetically and using an array of magnetic field sensors in a base with an aperture, it is possible to shift the array so that the aperture is precisely aligned with the non-visible hole.

主权项

1. A method of locating an object that is lying behind an opaque surface, the method comprising:
providing in the neighborhood of the object a variable strength magnetic field; using an array of magnetic field strength sensors for sensing the magnetic field strength of the provided magnetic field at a plurality of positions relative to the object, the array of magnetic field strength sensors being associated geometrically with a machining guide, such that the machining guide and the array of sensors are fixed positionally one relative to the other; interrogating the sensors in the array to determine a value of the field strength at at least a majority of the sensors in the array; receiving sensor responses from the interrogated sensors, and analyzing the received sensor responses to determine the displacement between the object and the machining guide; and moving the array and machining guide by means of manual control based on the determined displacement such that once the machining guide is located immediately and centrally over a point on the opaque surface that is opposite the object lying behind, the position of the array and machining guide is fixed, wherein said fixing is effected by locking the array on to the surface via vacuum pads at one of two levels of holding force, one level providing a sufficient holding force to attach the array and machining guide to the surface sufficiently loosely for the performance of said moving, and another holding level at which the array and machining guide are firmly clamped in a fixed position against the opaque surface.