Pick window on conveyor.

Hello all -

Most of the things I simulated involve having a robot pick products off of a conveyor. 90% of the time, the product is moving when I pick it.

I'd like to simulate a "pick window" on the conveyor. In other words, I'd like to pick product on a certain zone of the conveyor, but nothing before or afterwards.

I've tried doing this with photoeyes and messages (have photoeyes place items in a queue), but the photoeyes don't have the resolution to detect every product on the conveyor.

Does anyone have a good idea how to solve this problem?

Thanks,
Neil

Attached is one example of how this can be done in Flexsim by using the BasicConveyor.

Basically, it releases the item at a certain decision point and then at the next decision point, it holds the item if it hasn't requested a transport yet.

That way the transport can only pull items off in a certain window.

The decision points are representative not of the entire window, but of the window at which the transport begins to go get the item.

The quirks with the model are that it will only work if sending to an object that will only receive one item at a time (such as another conveyor or a queue or processor with content of 1), and the visualization. The transport travels to the location where he was requested originally rather than where the flowitem actually is when the transport arrives. It would require more complicated logic to get the visualization to look correct.

This is a great example of a starting point in how to use the BasicConveyor. It shows what functions to call to receive and release items and get them conveying. The BasicConveyor object gives you great flexibility in controlling conveyor behavior.

The model has been posted to the downloads section.

http://www.flexsim.com/community/for...do=file&id=201

The download of the Sample doesnt work. I got everytime the message:

Warning: copy(downloads//ec_tmp/Sample_BasicConveyor.zip) [function.copy]: failed to open stream: Permission denied in [path]/downloads.php on line 701
ERROR: File not found.

regards Tobias

hi, I downloaded the model and tested it in flexsim 6. But it seems the pick window doesn't work correctly.
After an item passed the pick window, it still was picked by the robot, why?
You can set colors for items to see the effect.

Originally Posted by zhang xin

hi, I downloaded the model and tested it in flexsim 6. But it seems the pick window doesn't work correctly.
After an item passed the pick window, it still was picked by the robot, why?
You can set colors for items to see the effect.

I upload the file here. I only change the color of item.

I think i understand the logic now. This model cannot meet my requirement. I need a real pick window defined by two decision points. an operator will pick items in the pick window to a buffer. How to implement this logic? thanks in advance.

I had the same problem than you. Here is my solution. Let me know if you have any question.

Originally Posted by Phil BoBo

Attached is one example of how this can be done in Flexsim by using the BasicConveyor.

Basically, it releases the item at a certain decision point and then at the next decision point, it holds the item if it hasn't requested a transport yet.

That way the transport can only pull items off in a certain window.

The decision points are representative not of the entire window, but of the window at which the transport begins to go get the item.

The quirks with the model are that it will only work if sending to an object that will only receive one item at a time (such as another conveyor or a queue or processor with content of 1), and the visualization. The transport travels to the location where he was requested originally rather than where the flowitem actually is when the transport arrives. It would require more complicated logic to get the visualization to look correct.

This is a great example of a starting point in how to use the BasicConveyor. It shows what functions to call to receive and release items and get them conveying. The BasicConveyor object gives you great flexibility in controlling conveyor behavior.

The model has been posted to the downloads section.

http://www.flexsim.com/community/for...do=file&id=201

Dear Phil, I tested the model with flexsim 6.0.2, and found that the second decision point(HoldItem) had never been triggered, and the model didn't work as it is supposed to, any idea?

Originally Posted by CanitrotCex

I had the same problem than you. Here is my solution. Let me know if you have any question.

Thank you, CanitrotCex. I see your model. I am not very sure if I understand your model completely. My requirement is that when an item passed the pick area, the operator cannot catch up it. So, different density of items on the conveyor will result in different pick capability. Could your model achieve this?

In my model, each manipulator takes the first box which is in its defined area. Try to increase the inter-arrival time to see the difference.