Estimation of Depth, Orientation, Length and Diameter of Long, Horizontal FerrousRods Using a Fluxgate Magnetometer

摘要

A patented hand-held instrument has been built that is the first instrument toexplicitly locate ferrous rods parallel to and buried behind or beneath a plane of measurement by analyzing magnetic field position data. The instrument has several useful applications, in particular the detection and characterization of reinforcing steel in concrete. The instrument consists of a fluxgate magnetometer and position sensor unit enclosed in a small box which is moved by hand somewhat like a computer mouse. A cable connects the sensor unit to a processor unit, containing a microprocessor, A/D, displays and batteries. An operator scans the sensor unit over the measurement surface, guided by the microprocessor, which controls the simultaneous collection of magnetic and position data. The microprocessor then uses simple algorithms to estimate location parameters, rod length and diameter. This report describes the final version of the instrument. Experimental magnetic data from horizontal rods are presented and compared to two simple models, the infinite cylinder and the long prolate spheroid. It was found that there was very poor agreement between both models and the experimental data. Experiments using the instrument to estimate the parameters of a horizontal ferrous rod buried under a horizontal measurement plane are also described. Reinforcing steel, Reinforcing rod, Concrete, Rebar, Magnetometer, Fluxgate, Magnetic field, Position, Detect, Locate, Identify, Model, Spheroid, Cylinder, Microprocessor, Remnant.