This page gives a short overview of the variable TaskCompleted; and then a more in depth look at how the variable can be used in Pally:

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In Short: TaskCompleted

In Detail: TaskCompleted

The boolean variable TaskCompleted is used to verify that the robot has placed box(es) on the pallet, and the program can proceed to the next position or not.

It is possible to manually set the value for this variable, which should then be done in the beforeRelease-callback.

Pally will set TaskCompleted (to either True or False) based on if it detects sufficient vacuum level in the gripper before it releases the box. This, as the vacuum level in the gripper will signal to Pally that the gripper is lifting a box (i.e a successful run). If the vacuum level in the gripper is low, then it signals that there is no box present on the gripper (i.e an empty run).

Gripper Configuration for TaskCompleted

The signal that is used to check the vacuum level in the gripper, and subsequently set the value for TaskCompleted, is set in the Pally installation node. It is the Vacuum lost-signal in the Gripper → Input/Output tab:

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The signal for ‘Vacuum lost' is used by Pally to check the vacuum in the gripper

If the gripper in use does not have a vacuum sensor, set the Vacuum lost-signal to -Always-LOW- in the Pally installation node (see screenshot above). In this case, Pally will always set TaskCompleted to True.

If the gripper does have a vacuum sensor, then a digital input should be set for the Vacuum lost-signal. Examples of grippers that have vacuum sensors are:

• Schmalz FXCB - Foam

• Schmalz FXCB - Suction cups

Whenever one of the Schmalz grippers is selected as the gripper type in Pally, the Vacuum lost-signal is automatically set to the digital input that corresponds to the vacuum lost signal for that gripper. In the Schmalz case, there is a sensor that detects if vacuum is present, not lost. Therefore, to make the logic correct in Pally, the signal for vacuum lost with one of the supported Schmalz grippers is inverted (see screenshot below).

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An example showing how the ‘Vacuum lost’ signal is automatically set to ‘tool_in[1]’ when the gripper type is set to ‘Schmalz FXCB - Foam’.

If you have a gripper with a vacuum sensor, and it is not a Schmalz FXCB gripper, then select the Custom vacuum gripper-type in the Pally installation node. It is then possible to assign a digital input for the Vacuum lost-signal as you please.

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An example showing how the ‘Vacuum lost’ signal can be manually set when the gripper type is set to ‘Custom vacuum sensor’

Logic in Pally Code for TaskCompleted

The logic in the Pally code gives more insight as to how the TaskCompleted variable is used and altered:

global TaskCompleted = HasVacuum()

# USER CALLBACK
usercallback_beforeRelease()

# control the gripper, turn off vacuum
ReleaseBox()

if (TaskCompleted):
  # box has reached the pallet, can proceed to next box
  SetCurrentTaskCompleted()
else:
  # box has not reached the pallet, repeat last position
  CancelCurrentTask()
end

# USER CALLBACK
usercallback_afterRelease()

The logic in the Pally code shows how the TaskCompleted is set based on the vacuum level (but it can also be overwritten in the beforeRelease-callback), and then used to verify if boxes were moved or not

As shown in the code snippet from above, setting the TaskCompleted = True in the beforeRelease-callback, will ensure that all movements of the robot are treated as successful runs - where Pally assumes that the boxes in the current task have been placed on the pallet. If TaskCompleted = False after the beforeRelease-callback, then Pally will not count the current task as completed. This will lead to Pally re-trying to place the box(es) in the current task.