The Horizon Control UC describes the process of manually correcting the cutting heights to optimize coal extraction and reduce rock cutting in specific areas. The operator uses the Roof Support System’s control panel to send correction data to the shearer.
If a new user input for either the roof or the floor offset is done, the Roof Support System sends the offset for the corresponding area (identified by StartShield and EndShield) to the Shearer.
The Shearer uses these offsets for controlling the arm heights in the next shear. Optionally, the Roof Support System can read the present FloorOffset and RoofOffset of all shields from the Shearer to allow the user to see the currently applied values. Figure 8 contains the sequence diagram of this UC.
Figure 8 – Sequence diagram of the Horizon Control Use Case