Simplified models of piecewise rigid support structures for power-loaders operating on longwall coal-faces are shown to be amenable to analysis by z-transform methods. Such analysis predicts that increasing sufficiently the length of the sub-sections of the structure (compared to the inherent delay within the vertical steering system of the machine) should stabilize the vertical steering of the entire coalface. Increasing the width of the structure to embrace more than two consecutive cut floors is shown analytically to eliminate the need for electronic tilt-feedback in control systems. In general terms, these analytical predictions are shown to hold good in detailed simulations of the system that eliminate the simplifications demanded by the analytical method. The general conclusion of the work is therefore that an increase in the size of support structure segments can potentially reduce the complexity of steering control systems. The size-increase must be substantial, e.g. to four to five times the size of conventional structures.
The Effect of Large-Scale Structures on the Stability of Coal-Face Steering
