Concrete reinforcement accurately located by metal detector - with movements in two perpendicular directions measured as functions of voltage variations

摘要

Appts. for detecting and surveying reinforcement in concrete comprises a metal detector. As the sensing head of the detector is moved in a first direction a first voltage is varied, while as it moves in a second direction perpendicular to the first a second voltage is varied; the first voltage is supplied to the first input of an X-Y plotter, while the second voltage is added to the output voltage of the detector and is supplied to the second input of the plotter. Pref. the sensing head moves in one direction along a bar, while this bar itself can be moved in the second, perpendicular direction. Used for detecting reinforcement with high accuracy, particularly in nuclear containment structures, to enable the correct position for drilling an anchor hole or the like to be determined. The high accuracy of location is required to ensure that holes are drilled at a sufficient distance from the embedded reinforcement.