Novel In Situ Boundary Detection Algorithm for Horizon Control in Longwall Mining

Real-time horizon control of the cutting head is very important in longwall mining for maximizing production, minimizing wear, and reducing postimpurity processing cost. If the horizon control sensor has to be mounted directly onto the cutting drum, then it needs to withstand the impacts from mining debris as well as shock and vibration at an average level of 26 Gs and a peak level of 100-G force. A single-frequency boundary detection sensor has been developed for this purpose for its simple design and extremely high measurement rate compared to other more sophisticated pulsed or swept-frequency radar sensors, and thus is more suitable for fast rotating cutting drums. However, the accuracy and effectiveness of this method in practice are severely limited by: 1) the interference of the much stronger reflection arising from the air-ground interface and 2) the uncertainty of the permittivity and conductivity of the ground. These two issues are alleviated by the proposed practical in situ calibration procedure discussed in this letter. This procedure only requires more than four calibration control cuts prior to the normal longwall mining cuts. The effectiveness of this method is demonstrated in this letter via both simulated and experimental data.