AGV parking position using AGVmodule

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christoph gruber asked Nov 22, '19 Christoph G5 commented Dec 28, '19

AGV parking position using AGVmodule

Unfortunately, I have a problem in understanding to use waypoints and LFNW points. In the model enclosed I have arranged the AGV parking position in an inner circle. Tow problems appears.

1.How can I manage that the AGV´s don´t block each other? If the first AGV get an order the second AGV have to drive in the first position (parking position have to change). And a new order to a free AGV (a AGV on a parking position) have to go to the AGV on the first parking position!

2.And I don´t know how I can manage that AGV with the order to put items from Queue_pull to Queue_wait and orders from Queue_wait to Queue_finish take the second inner circle. I tried this with a waypoint on AGV network properties, but no change. The AGV´s work off one after the other “Lock for next Work Point” on ControlPoint7.

agv-logic-parking-circle.fsm

How can I solve the problems?

Thanks in advanced

Software Version:

FlexSim 19.2.3

agv network agv module parking point agv network properties parking

agv-logic-parking-circle.png (162.1 KiB)

agv-logic-parking-circle.fsm (182.7 KiB)

5 |100000

Attachments: Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Answer 1 · 2019-12-13T16:02:04Z

Brandon Peterson answered Dec 13, '19 Christoph G5 commented Dec 28, '19

Christoph, I will try to answer your questions for you but @anthony.johnson may be able to clear things up if I make a mistake or don't fully answer the question for you.

I think the first thing is to fully understand what parking is used for in the AGV module (process flow) that you are using. An AGV can only be parked by a LFW point that has ParkPoint connections. An AGV will only be parked by the LFW when the battery is low or (based on the load balancing heuristic) there is not enough work for it to do. An AGV will only be un-parked after it's battery is charged (if it was parked because of a low battery) and when there is enough work to justify another active AGV (based on the load balancing heuristic).

In regards to your first problem, the parking behavior is only waking 1 AGV up when a task arrives. This means that the other AGV remains parked at its initial parking spot and will block the path for any AGV that comes along behind it. The easiest way to solve the problem is to create the paths so that an AGV has a clear path into and out of each ParkPoint. If you need the paths to remain like you have them then you will need to modify the AGV process flow so as to wake up both AGVs so that the 2nd AGV can move to the next ParkPoint. If you do this you will need to have a ParkPoint connection from "ControlPoint11" to "ControlPoint10" in your model and you may need to change the NLFW (Next Look For Work) connections as well.

For the second problem let me explain a little about how the LFW (Look For Work) and NLFW (Next Look For Work) connections work. When an AGV arrives at a LFW control point it checks to see if there is work to do. There will be work to do if the control point is connected to an object that has an item to pick up OR if it is connected to another control point by a LFW connection that is connected to an object that has an item to pick up. If there is work to do then it will travel to the pick up control point (itself, LFW control point, or PickUpPoint) to do the work. If there is not any work to do then it will travel to the NLFW control point.

I was able to get your model to work like you wanted after I modified your AGV path and connections to look like the attached image and removed the way points. There is still the problem with the AGVs blocking each other at the parking locations but you would need to decide on one of the solutions from above to address that.

I hope this helps, Brandon

changedagvpath.png (164.6 KiB)

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Christoph G5 commented · Dec 28, 2019 at 11:25 AM

Hi @Brandon Peterson

I will do this. Have a nice holyday and a good start to 2020!

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christoph gruber commented · Dec 20, 2019 at 06:50 AM

Hi Brandon, thank you very much for your explanation. I think I used to many connections / NLFW control points! With your modification the model works fine (except parking problematik). AGVs now use inner circle because there is no waypoint with NLFW and so the AGVs take the shortest way - ok I understand. But nevertheless....

in my real model I have big problems to find the right connections. AGVs drives a lot of extra circles without finding items, other AGVs are parking even there is enough work!

I can´t show or explane detail information for discretion. How can I go on to manage the "4 lanecircles" - or loosen the knot in my head? For confidentiality reasons is it possible to discuss my problem in a privat e-mail?

Thanks for an answer in advance

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agvlanes.png (95.2 KiB)

Brandon Peterson ♦ christoph gruber commented · Dec 20, 2019 at 06:29 PM

@christoph gruber

You picture definitely shows a complex system of loops. The default way to handle this is with the NLFW and LFW connections. By default any CP with multiple NLFW connections will sent AGVs in a round robin fashion to the NLFW CPs (i.e. A, B, C, A, B, C...). The LFW connections define how early an AGV can be assigned the work available at a given CP (CPs can have multiple LFW connections).

Getting all the connections right so as to create an efficient system is not always an easy task (especially in your case). However, it is much easier if you have a clear definition of how the system is currently working or will work.

Going beyond what is available with NLFW and LFW connections is possible and there are untold numbers of ways to do it. However, there is a big difference between "How can it be done in FlexSim?" and "How is/can it be done in the real world?". The results of your model could be exceptionally wrong if we helped you model a design that solved the problem in FlexSim but are not, could not, or would not be replicated in real life.

If you could let us know how the system currently works in the real world or how the supplier/builder plans to control the system (or currently controls similar systems), then we could help you replicate that in FlexSim.

Brandon

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christoph gruber Brandon Peterson ♦ commented · Dec 23, 2019 at 12:46 AM

Thank you so much @Brandon Peterson For confidential reasons is it possible to write in a privat room or per e-mail and not in the general forum?

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