Tasks

A Task orchestrates different Instances via operations to result in a logical process flow. Such a Task does not need to describe who is going to transport an item - it is important that the item is transported.

Generally speaking a Task in LoTLan describes that a amount of items should be picked up at some location and be delivered to another location. A Task can optionally be triggered by an event, but it can also have follow up Task or be repeated. Even an event at the end of a task which is expected can be described.

Task {name}
    Transport
    From        {transportOrderStep_pickup}
    To          {transportOrderStep_destination}
    TriggeredBy {none|event|time}
    OnDone      {none|followUpTask}
    FinishedBy  {none|event|time}
    Repeat      {none = once|1, ..., n|0 = forever}
    Constraints {none|constraint}
End

However, we start with some simple transportation tasks. To simplify this down in the following the simplest structure of a Task is build and later on extended with optional functionality. We also use these Locations and TransportOrderSteps not to inflate this page.

Location goodsPallet
    name = "productionArea_palletPlace"
    type = "pallet"
End

Location warehousePos1
    name = "warehouseArea_pos1"
    type = "pallet"
End

TransportOrderStep loadGoodsPallet
    Location    goodsPallet
    FinishedBy  agvLoadedAtGoodsPallet == False
End

TransportOrderStep unloadGoodsPallet
    Location    warehousePos1
    FinishedBy  agvLoadedAtWarehousePos1 == True
End

Example Simple Task

In the simplest form a Task in LoTLan just describes that an item should be picked up at some location and be delivered to another location:

Task transportGoodsPallet
    Transport
    From        loadGoodsPallet
    To          unloadGoodsPallet
End

In terms of the introduced example production hall this Task looks like depicted in the following figure.

Figure 1: Floor plan with Task TransportGoodsPallet

This Task transportGoodsPallet could be done by an AGV, that picks up a pallet from goodsPallet inside the production area and delivers it to the warehousePos1 in the warehouse area.

Example TriggeredBy Task

A Task can be extended with a TriggeredBy statement that activates that Task if the case occurs. This statement can be an event like a button press or be something simple as a specific time:

Event buttonPallet
    name = "A_Unique_Name_for_a_Button"
    type = "Boolean"
End

Task transportGoodsPallet_2
    TriggeredBy buttonPallet == True
    Transport
    From        loadGoodsPallet
    To          unloadGoodsPallet
End

In this example, the Task transportGoodsPallet_2 triggered by the event if the value is equal (== True).

In terms of the introduced example production hall this Task looks like depicted in the following figure.

Figure 2: Floor plan with Task transportGoodsPallet_2

This Task transportGoodsPallet_2 could be done by an AGV, that picks up a pallet from goodsPallet inside the production area and delivers it to the warehousePos1 in the warehouse area, when the button buttonPallet is pressed.

Example OnDone Task

A Task can be extended with a OnDone statement that activates another Task when the original one has ended:

TransportOrderStep loadEmptyPallet
    Location    warehousePos1
    FinishedBy  agvLoadedAtWarehousePos1 == True
End

TransportOrderStep unloadEmptyPallet
    Location    goodsPallet
    FinishedBy  agvLoadedAtGoodsPallet == False
End

Task refill
    Transport
    From        loadEmptyPallet
    To          unloadEmptyPallet
End

Task transportGoodsPallet_3
    Transport
    From        loadGoodsPallet
    To          unloadGoodsPallet
    TriggeredBy buttonPallet == True
    OnDone      refill
End

In this example another Task is introduced. This Task refill is the same transport as the formerly introduced transportGoodsPallet, just the other way around. On the other hand, transportGoodsPallet_3 here shows now the OnDone statement that points to refill an runs that Task if done. That means a concatenation of Tasks is allowed. Exploiting this behaviour infinite Tasks can be managed by pointing to each other. So refill could also point to transportGoodsPallet_3 in a OnDone statement.

In terms of the introduced example production hall this Task looks like depicted in the following figure.

Figure 3: Floor plan with Task transportGoodsPallet_3 & refill

This Task transportGoodsPallet_3 could be done by an AGV, that picks up a pallet From goodsPallet inside the production area and delivers it To the warehousePos1 in the warehouse area, when the button buttonPallet is pressed. After that the AGV executes the Task refill and so, it picks up a empty pallet From the warehousePos1 and delivers it To the goodsPallet location.