| 摘要 |
<p>A power loader having upper and lower cutting drums travels along the length of a face conveyor. Seam-top and seam-bottom sensors mounted on the power loader sense the heights of the true seam-top and seam-bottom. The data produced by these sensors during machine travel is not used to directly change the heights of the upper and lower cutters in the manner of an immediate-response automatic interface-follower system. Instead, to prevent the system from reacting and/or overreacting to changes in interface conditions, including changes which are physically insigificant and/or which, if fully reacted to, would exceed the floor and roof-negotiating abilities of the equipment, the system follows a preestablished interface-shape program. However, the true seam-top and seam-bottom height data from the sensors is fed into the process-control computer of the system, and used to modify and update the stored interface-shape program in a gradual ongoing manner. The computer ascertains, relative to predetermined criteria relating to the permissible rate of interface-shape program change in going from one power-loader working trip to the next, how much of the ascertained error in the interface-shape program can safely be eliminated per working trip for the successive working trips of the machine. And the erroneous intervals of the stored interface-shape program are then changed by such amounts during successive working trips, to gradually and stepwise dose out over a plurality of working trips the corrective reduction in the amount of the error exhibited by the stored interface-shape program.</p> |
