Self-calibrated boundary detection algorithm for horizon control in long-wall mining

A novel sensor was previously developed for detecting rock boundaries behind uncut coal for controlling the horizon of the cutting head in long-wall mining environments. This boundary detection method is based on extracting the thickness of the uncut layer from the complex reflection coefficient of a narrowband antenna that is mounted directly on the rotating cutting drum. The main practical challenges of this detection method lie in the ability to (1) mitigate the much stronger reflection from the air-mine interface and (2) obtain the in situ dielectric constant and conductivity of the cut material in active mining environments. This paper presents a novel in situ calibration method and real-time uncut thickness estimation procedure which could be practically implemented into normal long-wall mining operations, and thus allowing real-time monitoring of distance to rock boundaries behind the uncut seam. This paper will also discuss the uncertainty of the resultant estimated thickness in relation to the variation of cutting drum positions, dielectric constant, and air gap.