Forklift not raising forks when using A* (A Star) navigation

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martin.j asked Apr 18, '23 martin.j commented Jul 4, '23

Forklift not raising forks when using A* (A Star) navigation

I am trying to build a warehouse model where a forklift truck (FLT) taskexecuter delivers pallets to the correct storage rack slot and combining it with A Start navigation to avoid the FLT driving through the racks. Unfortunately when using A* The FLT does not raise its forks when placing the pallet.

I have found a similar questen as mine in the link below, but it appears that this problem was never solved when A* first came out:

https://answers.flexsim.com/questions/91112/why-does-not-the-forklift-lift-the-nails-using-a-n.html

I have tried changing the dropdown option on the taskexecuter that defines how offset travel is conducted, but it does not seem to work. Is there any way to use the A* network and make the FLT taskexecute work correctly?

Software Version:

FlexSim 23.1.1

warehouse animation storage system a star forklift travel

· 3

Jeanette F ♦♦ commented · Apr 24, 2023 at 03:21 PM

Hi @martin.j, was Jeanette F'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.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always unaccept and comment back to reopen your question.

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Matthew Gillespie ♦♦ commented · Jul 03, 2023 at 06:07 PM

@martin.jensen FlexSim 23.2 Beta was released today and includes this new feature:

"Updated Transporter forklifts to move during A* offset travel."

- from 23.2 Beta Release Notes

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martin.j Matthew Gillespie ♦♦ commented · Jul 04, 2023 at 07:08 AM

Awsome! I will go check it out. Thanks a lot.

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Answer 1 · 2023-04-18T20:44:19Z

Jeanette F answered Apr 18, '23 Jason Lightfoot commented Apr 19, '23

Hello @martin.jensen,

Can you change the option to Travel offset for load/unload tasks?

ForkLiftWithAStarNavigation.fsm

1681850627997.png (8.9 KiB)

forkliftwithastarnavigation.fsm (43.1 KiB)

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martin.j commented · Apr 19, 2023 at 07:24 AM

Hi Jeanette,

As I stated at the end of my question I have tried it and in short it doen't work while actually using A Start navigation.

There are four option in the offest travvel dropdown.

Do not travel offsets for load/unload tasks - This option entirely disables offset travel so that doesn't do what we whant it to.
Travel offsets for load/unload tasks - This option allow for offset travel and the FLT does lift its forks, but it doesn't use the A Star network meaning that the FLT will drive through the racks and other marked obstacles like other taskexecuters. Not what i wanted.
Do not travel offsets and block space on network - This option is only for network node travel and doesn't do what we want either.
Use navigator for offset travel - This final option is what I really want. Using the A Star navigator and avoiding obstacles while doing offset travel during load/unload tasks. Unfortunately it causes the FLT to not lift its forks.

So my question is what other options are there?

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Jason Lightfoot ♦ martin.j commented · Apr 19, 2023 at 10:09 AM

You may be able to travel to the correct location (in front of the correct bay for example) using Astar, and then switch the offset travel type on the forklift for the final part where the forks should be raised.

Alternatively, you could try overlaying fork kinematics during the Astar travel (not tested)

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