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Pablo R5 avatar image
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Pablo R5 asked tannerp commented

Chase the Rabbit , manufacture cells mode

HI


I am working or trying to simulate one manufacture cell and one thing that I want to simulate is the system called "Chase the Rabbit" , where one operator start in the first station and when the activity is finish he moves to he following station to preform the task and another operator start in the first station following the first operator and so on.


Does anyone know how to simulate this with this tool?.




I really appreciate your support on here.


Pablo

FlexSim 20.1.2
flexsim 20.1.2cellsmanufacure
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Pablo R5 avatar image Pablo R5 commented ·

Thanks Both for your answer , now I have a better idea how to implement it. Thanks

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Benjamin W2 avatar image
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Benjamin W2 answered tannerp commented

Here is an example using process flow. Your item will acquire an operator and keep that operator through it's entire workflow.

ChasingRabit.fsm


chasingrabit.gif (1.1 MiB)
chasingrabit.fsm (54.9 KiB)
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Julian Swedish avatar image Julian Swedish commented ·

@Benjamin W2: This ChasingRabit.fsm appears to be quirky.... 3D animation shows flow item separating from the operator between processors. Perhaps due to the process time in Process Flow Delay Activity is inconsistent with that of the Processor object in the Layout.

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Joerg Vogel avatar image Joerg Vogel Julian Swedish commented ·

@Julian Swedish, any example model is only a suggestion. You can call it a prove of concept, not more. If you look into each example model, you are going to find minor or larger flaws. Here both examples won't create a suitable state chart for operators, because they aren't involved in processing items. They currently just wait. This will be evaluated as an idle state for charts. If the models has been build straight with 3D logic, tagged resources and increasing priorities for the tasksequences, then state statistic of operators would include utilize state values whenever an operator has been called for assisting the processors.

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Benjamin W2 avatar image Benjamin W2 Julian Swedish commented ·

I would have to agree with Jorg. Your specific situation is going to be different, and you will have to tailor your experience to what you need. Although the box offset isn't quite right, the model statistics will be the same.

However, in this specific case, you might try a "Travel" then "Move Object" activity to correct the visuals.

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Julian Swedish avatar image Julian Swedish commented ·

@Benjamin W2 and @Jörg: I understand your position but I feel you may be missing my point - I downloaded the model from Benjamin W2 and studied it because I was interested in understanding the approach taken... check out the process time in the 3D layout object ( it is set to 10)... while you also have a corresponding Delay in the Process Flow which is set to an Exponential Distribution time. The model will not behave correctly when the Process Flow Delay time is generated to be less than the 3D Object time - ( for example: take a look at the difference occurring with the 2nd Flowitem arriving at Pocessor1 - the Process Flow Delay is less than 10 in this instance and therefore flow item advances to the next activity in the Process Flow, but not in the 3D model)... This creates a visible problem.

I have also unknowingly created this same discrepancy in the past, and it took awhile to figure the problem until Flexsim Tech Support staff finally pointed it out to me. This is the reason I wanted to alert others to the potential pitfall.

@Jörg - your example model Chase-RabBit is correct in this regard as you don't include a corresponding Delay for Procesor1 in the Process Flow .





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tannerp avatar image tannerp Julian Swedish commented ·

@Julian Swedish @Benjamin W2 @Jörg Vogel,

You're all correct to some degree. The main takeaway here is to keep your 3D logic and Process Flow logic straight. Both Ben and Jörg provided good approaches to building this model's logic (aside from the process time discrepancy pointed out by Julian). You can model the logic either way, as long as you don't have multiple entities handling the same thing.

It's important to only program one entity to handle each bit of logic in your model. This is a good example of how 3D objects and Process Flow can potentially conflict. In this model, the "Process Time" can be handled by the 3D Processor OR by the Process Flow, but it should NOT be handled by both.

Jörg's solution uses the 3D Processor to determine the process time and the Process Flow simply listens for the process to finish rather than generating its own process time. Alternatively, you could use Delay activities to generate process times in Process Flow, as Ben did. It's important, however, to then alter the logic in the 3D Processor so that it is not generating a second processing time.

In the end, the approach you take is subjective and depends on your personal taste. Hopefully this helps clear things up a little bit.

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Joerg Vogel avatar image
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Joerg Vogel answered Joerg Vogel commented

This example is a classic 3D approach as long as no transport is used. The statistic of processors and flow control are FlexSim engine driven. The Transport is event driven by Request Transport in Process Flow. The needed reference for Use Transport is set to NULL, because Process Flow acquires the operators on its own. Then it is a straight sequence of load, unload and waiting for event activities. chase_rabbit.fsm


sequence-rabbit.jpg (110.3 KiB)
chase-rabbit.fsm (48.8 KiB)
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Joerg Vogel avatar image Joerg Vogel commented ·

as a classic 3D model supported by process flow transport

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