The UC Unloading is the starting point of the Application Case Discontinuous Unloading.

This UC starts once the hauling machine indicates to the rock crusher, that it intends to start the Application Case Loading by calling the RequestForUnloading-Method. In case the rock crusher signals the hauling machine, that it can also start the Application Case Loading, it reads the current payload of the hauling machine.

Next, the Queueing and Positioning Use Cases for this Application Case take place, please refer to Chapter 4.2.2 and Chapter 4.2.3 respectively. After this, the hauling machine should be positioned so that it can unload into the rock crusher.

The unloading procedure can now start. By calling the StartUnloading-Method, the rock crusher indicates to the hauling machine, that it can start unloading its truck-bed. At any point in time, the rock crusher can inform the hauling machine to stop unloading using the StopLoading-Method. This could be, for example, due to an internal error within the rock crusher.

Once the unloading procedure has finished, the rock crusher requests the hauling machine to leave the unloading spot. A graphical representation of the UC is depicted in Figure 2.


Figure 2 – Sequence diagram of the Unloading Use Case