topic Re: Let AGV drive forward as much as possible in FlexSim Forum

Let AGV drive forward as much as possible

patrick_zweekhorst — Wed, 01 Mar 2023 14:26:39 GMT

[ FlexSim 23.0.4 ]

Hi,

It is possible to let the AGV drive forward as much as possible? The AGV can only rotate on the spot, but when it rotates it could choose between +90 degrees or -90 degrees. Depending on this choice the AGV will travel backward or forward after the rotation. Since traveling backwards is much slower it would in this model be best if the AGV rotates such that it will travel forward after the rotation.

We have been playing with the Turn Around Threshold in the AGV Network. Setting this value below 90 will let the AGV change travel direction all the time. Setting this value above 91 will never let the AGV change direction. You can play a little bit with these numbers in the attached model.

Would there be some kind of setting to let the AGV drive forward as much as possible?

One thing we thought about was to change the rotation in the custom delegate node. But one of the conditions there is:

The cumulative distances of the z parameters of all addkinematic() calls should be exactly rotation (param(2)).

So the end result of the rotation will never change. In the second model (RotateTestSolve_1) we tried to play around with this a little bit (ignoring the rule mentioned above). Getting the rotation correct is possible, but it won’t result in the correct driving speeds. So this is probably not a good solution!

Any help on this would be highly appreciated.

Patrick

RotateTest.fsm

RotateTestSolve_1.fsm

Re: Let AGV drive forward as much as possible

kavika_faleumu — Fri, 03 Mar 2023 17:09:52 GMT

Hey @Patrick Zweekhorst, it looks like your Turn Around Threshold for the AGV system could be increased to force the AGV to always go forward. The documentation states that an AGV

"will check the difference in travel direction for the respective paths, and if it must change direction by more than this amount in transferring to the new path, then it will stop and reverse its direction before continuing onto the path."

If you change it to be 180 degrees, then it will always drive in one direction. If you change the starting orientation of the AGV, then it will drive forward and rotate accordingly. Here's what it looks like after making those modifications.

rotatetest_kf.fsm

Re: Let AGV drive forward as much as possible

patrick_zweekhorst — Fri, 03 Mar 2023 17:16:49 GMT

Hi @Kavika F ,

Thank you for looking into this. However, when I change the threshold to 180 degrees I still get the same rotations, see the attached model. Changing the value to 180 works only if the vehicle starts driving forward, but that is not always the case, as in my example model. Or am I missing something?

RotateTest.fsm

Re: Let AGV drive forward as much as possible

kavika_faleumu — Fri, 03 Mar 2023 17:24:40 GMT

If you try a Turn Around Threshold of 181, it will turn around for that last case in the model.

Re: Let AGV drive forward as much as possible

patrick_zweekhorst — Fri, 03 Mar 2023 17:28:03 GMT

I see yes. In this model we would like the AGV to only rotate at curve. And when there are multiple options (+90 or -90) to take the one such that it can drive forward after the curve. But the AGV is not allowed to rotate 180 degrees at a straight path. Does this situation make sense to you?

Re: Let AGV drive forward as much as possible

kavika_faleumu — Fri, 03 Mar 2023 17:34:10 GMT

So to clarify, you want the AGV to start backwards, and then when it encounters a turn it continues going backwards?

Re: Let AGV drive forward as much as possible

patrick_zweekhorst — Fri, 03 Mar 2023 17:36:37 GMT

No, sorry for my bad explanation.

If the AGV start driving backwards it needs to drive backwards till the first crossing. At this crossing it should rotate such that it drives forward after the crossing.

If the AGV drives forward from the start, it needs to keep driving forward also after the crossing.

Re: Let AGV drive forward as much as possible

kavika_faleumu — Fri, 03 Mar 2023 17:43:56 GMT

If the AGV travelling backwards encounters a Forward-only oriented path, it will then face forward and continue forward from that point. Then you can reduce the Turn Around Threshold so it doesn't turn around completely on straight paths.

Re: Let AGV drive forward as much as possible

patrick_zweekhorst — Fri, 03 Mar 2023 17:51:33 GMT

Hi @Kavika F ,

That indeed solves the problem for all the situations we had in this model. For the actual model there is a small difference. If there is a 2 way path I can't set the travel direction on it. Because it depends on where the AGV comes from. Or do you have an idea to use in here as well? See that attached model.

RotateTest.fsm

Re: Let AGV drive forward as much as possible

patrick_zweekhorst — Thu, 30 Mar 2023 07:08:39 GMT

@Kavika F ,

I continued this discussion with Anthony and we some ideas to make this easier. Probably the best way to give this control to the user is to make two turn around around thresholds, one for when the AGV is driving forward and one for when the AGV is driving backwards.