AGV Path Planning

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Emily K asked Nov 24, '22 Andrew O commented Dec 9, '22

AGV Path Planning

In my previous post, there are all unidirectional paths.

To cope with bidirectional paths, I add a process flow "Path planning" and new control points connection, named "Alternative".

I want to check the AGV "travelPath" when it receive a task, if there are paths that coincide with other AGVs, then redirect the AGV to an alternative route by searching the current cp's Alternative, if there is no available path, delay. This method is reference to this post.

Due to my immature coding skills, there is some exception, any advice would be much appreciated!

Besides, how should I define the value of otherAGV in <Assign Labels> activity?

1124.fsm

Software Version:

FlexSim 21.2.4

agv agvpath agv process flow path planning

1124.fsm (179.5 KiB)

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Andrew O commented · Dec 09, 2022 at 04:37 PM

Hi @Emily K, was Jason Lightfoot's answer helpful? If so, please click the "Accept" button at the bottom of their answer. Or if you still have questions, add a comment and we'll continue the conversation.

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Answer 1 · 2022-11-24T11:48:31Z

Jason Lightfoot answered Nov 24, '22 Jason Lightfoot edited Dec 6, '22

You probably need nested loops or some other method to compare each of the two agvs paths to see if they overlap with one another along these lines:

treenode agvNavNode = current.find(">variables/navigator/1+");
treenode ownpaths = agvNavNode.subnodes["travelPath"];                            // The node that contains the path sections that are part of the current travel task
                                    // The path we are checking - initialized to the first path of the travel task


// Get path for other AGV
agvNavNode = otherAGV.as(Object).find(">variables/navigator/1+");
treenode otherpaths = agvNavNode.subnodes["travelPath"];


//Check AGV travel path
for (treenode pathSelf=ownpaths.first;objectexists(pathSelf); pathSelf=pathSelf.next)
    {
        for (treenode pathOther=otherpaths.first;objectexists(pathOther);pathOther=pathOther.next) {
        // Compare paths
        if(pathSelf.value == pathOther.value)
        {
.....etc

But at the moment I fail to see where you will get the otherAGV reference - in your model you set the label to zero.

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Emily K commented · Nov 26, 2022 at 09:07 AM

I found that in event OnCollision, it has option to define other AGV as other object, while current are all task executers in the model. The value of the label <otherAGV> is supposed to be other AGVs in my model, so that I could compare each of the two agvs.

Isn't the for loop in script is a nested loop?

I was thinking of getting the time window of each path so that I could know which path segment of two agvs will coincide precisely, is it possible?

Or do you have any feasible way based on your understanding of Flexsim?

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1669452906804.png (11.6 KiB)

Jason Lightfoot ♦♦ Emily K commented · Dec 06, 2022 at 02:53 PM

You could store a map of non-overlapping time slots by path by calculating all the acceleration/deceleration events over the network and then referring to that... this would result in no interaction blocking behaviours for any of the AGVs - which may be suboptimal. It would be a lot of work and I'm not sure it would give you what you want or need.

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Emily K Jason Lightfoot ♦♦ commented · Dec 06, 2022 at 03:32 PM

Thanks for your kind response :)
Could you give me more hints to achieve this? Should I start with process flow using custom code or module SDK?

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