Worker exiting a station and leaving entity

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Kaylinn
Posts: 3
Joined: Fri May 15, 2015 1:35 pm

Worker exiting a station and leaving entity

Post by Kaylinn » Wed May 27, 2015 10:31 am

Hi folks! I'm trying to model a production line with one worker and several stations that he visits/uses. The process is in a specific order (ie, the entities move in a direct path) but the worker is free to float between stations as needed. The situation I'm facing now is that some stations require him during the beginning and ending, excluding processing time, and other use him the whole time. I have a station that he is called to be at, and he goes and completes the task, then exits the station leaving the entities, goes to finish another task, and then returns to the original station to pick up the entities he left before. How do I make him take those entities to their next location before leaving? I've tried setting the "task selection strategy" to "largest priority" and assigning higher priority to the entities at the original station, but it's not working. Any help would be very appreciated! Thanks :)

PS, does anyone have any thoughts/preferences between using processes to seize the worker and delay during the task versus using the station's secondary resources to call him? They seem to be the same thing to me and I was just wondering if there are any tips/tricks/reasons to use one over the other? Double thanks!

dsturrock
Simio Team Member
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Location: Sewickley, PA USA
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Re: Worker exiting a station and leaving entity

Post by dsturrock » Wed May 27, 2015 10:49 am

1) If you are not already using a Workstation (instead of a Server) you probably should because it has the 3 stage processing that you appear to need. Or use the new task features added to Server around sprint 120/121.

2) The problem you are having is because between the "work" phase and the "move" phase there is a delay. Even if this is a zero-time delay, the Worker momentarily goes idle, and it gives any other waiting entity a chance to seize the worker before this entity can get it back. One of our SimBits has a "hack" type solution to this, but a much better solution is available using the resource reservation features added to sprints 121/122. This new feature lets an entity release a resource, but prevents any other entity from seizing that resource for a specified time period.

3) There are often multiple ways of approaching a problem. The simple answer is to use the one you understand the best or the one that is clearest to explain to others.
In general, I personally try to stay inside the object properties (no processes) as much as I can because it is easier for most users to understand (e.g. more self-documenting). But if I need to add process logic for any reason, then I am inclined to put everything in the processes so I can see all my logic together in one place. But that is just my personal preference.
Dave Sturrock
VP Operations, Simio LLC

Kaylinn
Posts: 3
Joined: Fri May 15, 2015 1:35 pm

Re: Worker exiting a station and leaving entity

Post by Kaylinn » Wed May 27, 2015 11:02 am

Thank you for your quick reply!

Yes, I am using workstations. Could you tell me more about this resource reservation? That's a new one for me.

And I just had another question. I am modeling a wash station that takes 30 minutes for the first piece, and an additional 5 for each piece after that(so a batch of 3 would take 40 minutes, a batch of 6 would take 55 minutes, and so on) but I'm having some trouble putting this into a processing time. The added problem is that the number of entities changes. Currently I'm using a source that produces one "shipment" a day with "Entities per arrival" set as "random.triangular(3,13,19)" which is working fine for my quantity, but I don't know how to relate that into the processing time of the next workstation.

dsturrock
Simio Team Member
Posts: 1453
Joined: Thu Mar 13, 2008 12:35 pm
Location: Sewickley, PA USA
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Re: Worker exiting a station and leaving entity

Post by dsturrock » Wed May 27, 2015 12:58 pm

Look to the release notes and help of the last couple sprints for more information on resource reservations. BTW, more related features are still on the way.

Regarding your process time there are many ways to handle it based on your situation.
--If you have a single entity arriving that represents a batch, then the easiest approach is a processing time something like 25 + (BatchSize * 5) to get 30 for the 1st one and 5 for every additional one.
--If each batch comes as a series of similar entities that is different from the rest (perhaps just an order number) then you might use the Workstations built-in setup time where if the order number is different, there is a 25 minute setup time, otherwise its 0. But in either case the processing time is 5.
Dave Sturrock
VP Operations, Simio LLC

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