Operator's state is "travel loaded" even though he has nothing

Question

question

ksugai asked May 29 2023 at 9:41 AM Julie Weller commented Jun 07 2023 at 1:38 PM

Operator's state is "travel loaded" even though he has nothing

In this model, Operator1 hands over an item to Operator2 at the origin. After Operator1 finishes his task sequence, his state should be "idle" or "travel empty". However, it is "travel loaded" except for the first delivery.

This problem seems to be solved by putting 0 second delays of Task Sequence before "Finish TS of Operator1", but I want to know why 0 second delays is needed in this case.

Software Version:

FlexSim 23.0.8

state synchronize tasksequence delay

image.png (174.1 KiB)

handing-over-an-item.fsm (43.3 KiB)

· 1

______

Cookie preferences

Your privacy is important to us and so is an optimal experience. To help us customize information and build applications, we collect data about your use of this site.

May we collect and use your data?

Learn more about the Third Party Services we use and our Privacy Statement.

Strictly necessary – required for our site to work and to provide services to you

These cookies allow us to record your preferences or login information, respond to your requests or fulfill items in your shopping cart.

YES

Improve your experience – allows us to show you what is relevant to you

These cookies enable us to provide enhanced functionality and personalization. They may be set by us or by third party providers whose services we use to deliver information and experiences tailored to you. If you do not allow these cookies, some or all of these services may not be available for you.

YES

NO

Customize your advertising – permits us to offer targeted advertising to you

These cookies collect data about you based on your activities and interests in order to show you relevant ads and to track effectiveness. By collecting this data, the ads you see will be more tailored to your interests. If you do not allow these cookies, you will experience less targeted advertising.

YES

NO

Are you sure you want a less customized experience?

We can access your data only if you select "yes" for the categories on the previous screen. This lets us tailor our marketing so that it's more relevant for you. You can change your settings at any time by visiting our privacy statement

Your experience. Your choice.

We care about your privacy. The data we collect helps us understand how you use our products, what information you might be interested in, and what we can improve to make your engagement with Autodesk more rewarding.

May we collect and use your data to tailor your experience?

Explore the benefits of a customized experience by managing your privacy settings for this site or visit our Privacy Statement to learn more about your options.

Answer 1 · 2023-05-30T05:28:33Z

Arun Kr answered May 30 2023 at 5:28 AM ksugai commented Jun 02 2023 at 9:34 AM

The "Breathe" activity solves the issue because adding a "Breathe" activity synchronizes the events. Before the loading of the item from operator1 is fully completed you are sending the operator1 token to finish the task sequence. As a result, operator1 remains in the "travel loaded" state, to avoid this issue you can add the "breathe" activity which will allow the operator1 token to remain in the "breathe" activity when the loading is completed. And finally, the state is rightly shown. Pls, refer the article on the trouble shotting process flows link given below.

https://docs.flexsim.com/en/23.1/ModelLogic/AdditionalConcepts/TroubleshootingProcessFlows/TroubleshootingProcessFlows.html#delays

Regards,

Arun KR

· 2

ksugai commented · Jun 02 2023 at 7:51 AM

Thank you for your reply.

I understood the reason operator 1 remains in the "travel loaded" state without "breathe" activity.

I used the 0 Second Delays of task sequence in the model, but when I replaced the activity with the general Delay activity, the state of operator1 was not rightly shown.

Please tell me why specifically the 0 Second Delays of task sequence is need in this situation.

0 ·

Felix Möhlmann ksugai commented · Jun 02 2023 at 8:44 AM

The timing here is quite complex since it also depends on which operator arrives at the passover point first. You can see this when you change the position of the queues. If Operator2 arrives first, the delay task will also not work.

Another thing is that the task activities can be throught of as two steps, creating the task and executing the task.

Here is what I believe the ordering to be:

Delay Task - Operator1 arrives first:
Delay Task is generated -> Load Task is generated -> Delay Task starts -> Load starts -> Delay Task Ends -> Task Sequence of Operator1 Ends and the new one starts -> Travel Task is generated while item is still held by Operator1

Delay Task - Operator2 arrives first:
Load Task is generated -> Delay Task is generated -> Load starts -> Delay Task starts -> Load Task Ends -> Delay Task Ends -> Task Sequence of Operator1 Ends and the new one starts -> Travel Task is generated while no item is still held by Operator1

General Delay - Operator1 arrives first:
Delay Starts -> Load Task is generated -> Delay Ends -> Task Sequence of Operator1 Ends and the new one starts -> Travel Task is generated while item is still held by Operator1

General Delay - Operator2 arrives first:
Load Task is generated -> Delay Starts -> Load starts -> Delay Ends -> Task Sequence of Operator1 Ends and the new one starts -> Travel Task is generated while item is still held by Operator1

Compare this to using a Move Object activity in place of the Load activity:

Delay Starts -> Items are moved in an instand -> Delay Ends -> Task Sequence of Operator1 Ends and the new one starts -> Travel Task is generated while no item is still held by Operator1

You can see all this for yourself by stopping the model and stepping through it one event at a time. You will see difference of which token advances first.

In summary: Sometimes activities/tasks actually consist of multiple actions that each take 0s. A 0s Breathe will only delay the token until all other currently pending events at that time have finished. If a new event is created after the delay starts, the delay will finish first.

In those instances I personally then often use delays with a finite time (like 0.0001s) (calling them 'Long Breathe' to be able to see the resulting timing at a glance).

0 ·

question