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Craig DIckson avatar image
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Craig DIckson asked Joseph Gillespie commented

Controlling the travel threshhold in A*

We're building a model using A* controlling task executers to deliver flow items to queues.

How can I control the travel threshholds on the queues? I need the items to be dropped off actually at the queue, but the threshhold is much wider than that that, covering a space much larger than the queue itself. I really only want one node, or at most one grid space around it, as opposed to at least three (see screenshot.)

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Joseph Gillespie avatar image Joseph Gillespie commented ·

@Craig DIckson

Queues shouldn't have travel thresholds that big. Could you share your model so that we can get a better look at the problem?

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Craig DIckson avatar image Craig DIckson Joseph Gillespie commented ·
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a-star-agv-test.fsm (34.7 KiB)
Craig DIckson avatar image Craig DIckson Craig DIckson commented ·

FYI, this is just a 'scratch' model to test how A* works and see if it is suitable for real model.

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1 Answer

Joseph Gillespie avatar image
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Joseph Gillespie answered Joseph Gillespie commented

@Craig DIckson

I don't know why I didn't think of this earlier, but your problem is actually pretty simple. You said that you want the task executors to drop off items at the queues, but that is impossible as long as you have your queues inside of a barrier. Barriers are designed so that task executors cannot enter them, so you will either have to edit or change the shape of the barrier to allow the task executors to reach the queue or you will have to accept them depositing items from a distance. As long as your queues are inside of an impassible barrier, the task executors will not be able to reach them.

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Craig DIckson avatar image Craig DIckson commented ·

@Joseph Gillespie I don't think it's quite that simple. Even if I put the queue in open space, the agvs will deliver to several points on the queue's periphery, not to the single location of the queue, which is what I want. What that means is that they often try to deliver in the main travel path, not in the little safe harbor. I moved the queue into the barrier so that none of its points were in the main path, but sometimes it still made a lot more points as you saw.

There is not a way to control the size of the travel threshold so that things are delivered to one and only one point?

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Phil BoBo avatar image Phil BoBo ♦♦ Craig DIckson commented ·

If you want to travel to a specific point, use a Travel to Loc task to travel to the queue's location rather than a Travel task to travel to the queue object.

If you travel to a specific location, then it will go to that specific location instead of using a travel threshold.

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Joseph Gillespie avatar image Joseph Gillespie Craig DIckson commented ·

@Craig DIckson

Another option would be to use a divider layout like this:

As long as you don't include the queue as a barrier (as long as the queue isn't connected to the A* navigator), the AGVs should travel right up to the queue when unloading items.

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capture.png (13.9 KiB)
Craig DIckson avatar image Craig DIckson Joseph Gillespie commented ·

Hmm. The problem with what you drew is that I need the harbor to be 2 vehicles wide, and after the Unload task the vehicle is directed to move aside into the adjacent parking location, and that location happens to contain another red point (it's the top right in your picture). So sometimes a vehicle comes to the parking location to drop instead.

The other problem with the Travel to Loc vs Unload is that I use the Unload to trigger that movement to parking. Using a Travel to Loc and then a Move item doesn't fire that trigger. (See my next question posted about half an hour ago.)

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