topic Re: How to instruct AGV to stay /travel to park points if there is no work in FlexSim Forum

How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Sat, 11 Feb 2023 17:14:47 GMT

[ FlexSim 22.2.1 ]

Hello Everyone,

When there are no objects to pick up or drop off, the AGV continues to loop or travel in search of work. This is a problem that I'm attempting to fix. As tracking the empty travel metric has been restricted due to the AGV's looping/unnecessary travel. Therefore, the dash board's pie chart indicates that the vehicle is moving more than 50 KM (or 50000m) every day, which isn't practical. So it may be somewhat realistic if the AGV Empty travel is simply for collecting or returning to its park position.

How can the problem of unnecessary travel, job searching, or looping be resolved when there is nothing to pick up or leave off?

I am using standard AGV process flow template to instruct AGV to pick or drop items.

Any Suggestion or help?

Re: How to instruct AGV to stay /travel to park points if there is no work

jason_lightfoot_adsk — Sat, 11 Feb 2023 23:13:06 GMT

Which template and have you added parking points?

Re: How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Sun, 12 Feb 2023 08:23:31 GMT

@Jason Lightfoot Thankyou for the response. In my model I am using Advanced AGV template and park points are also assigned to AGV network or path

Re: How to instruct AGV to stay /travel to park points if there is no work

moehlmann_fe — Sun, 12 Feb 2023 09:04:55 GMT

Is the control point that the parking points are connected to part of the NextWorkPoint loop? Because an AGV has to acutally pass that point in order to "see" the park point and check whether it should park or continue to travel.

Re: How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Sun, 12 Feb 2023 11:45:54 GMT

@Felix Möhlmann I appreciate your reply. Yes, The nearest Nextwork point was connected to the parkpoints. The model below shows two AGVs traveling in two separate tandems or circuits. I assigned each AGV to its own AGV process templete. It was discovered during model simulation that an AGV1 still travels in tandem 1 in search of work while an item is available in tandem 2. And when there is work in tandem 1, this also occurs with AGV2. I don't sure where I went wrong, but I continue to use two separate AGV process flow templates for each AGV, and I've discovered that this is the main cause of unnecessary empty travel for AGVs.

Could you please advise me on how to resolve this?

such that each tandem serves as a separate workplace for its individual AGVs, who should only travel when there is work to be done in their tandems.

AGV Empty Travel isuue.fsm

Re: How to instruct AGV to stay /travel to park points if there is no work

jason_lightfoot_adsk — Sun, 12 Feb 2023 13:07:00 GMT

You'll need to push to the AGV work list using a partition that matches one referenced by the initial pull in the "Work Generation" section of the process flow. Use something that identifies the circuit for the partition - that could be an AGV, fixed resource or just a numeric value.

Re: How to instruct AGV to stay /travel to park points if there is no work

e_yiing98 — Mon, 13 Feb 2023 08:29:00 GMT

@Ajay M Maybe this answer will help.

Re: How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Mon, 13 Feb 2023 08:38:50 GMT

@Jason Lightfoot Your suggestion was efficient and Thankyou very much and the AGV's empty travel was somewhat reduced.

However, there is one additional problem that I've noticed: the AGV takes a long route even the pickup points close to its prior dropoff point. You can see an example of this in the image below. The blue-circled object is the one that the AGV will pick up. The red line indicates what appears to be the quickest route between an AGV's current position and the pickup location. The AGV appears to be following this path, which is black, rather than the red one, which is the shortest. Regarding other pickup and drop-off locations, I discovered this problem as well.

One more issue i found was even dropping off the items to a particular dropoffpoint still AGV is not taking a shortest path to its parking position.

Any Suggestion Please?

here is the working model Empty travel issue2.fsm

Re: How to instruct AGV to stay /travel to park points if there is no work

moehlmann_fe — Mon, 13 Feb 2023 09:20:18 GMT

The AGV Process Flow templates are meant to mimic a specific kind of task distribution logic. They work by sending the AGVs along the NextWorkPoint loop. At every point, it will check if there is something to pick up (or drop off, or if the AGV should park or charge, ...).

The only exception to this is that the AGV will travel directly to an unload destination if loading an item caused it to reach its maximum load capacity.

If your goal is to just move directly from location to location, without any preset "patrolling" route, then you can achieve this with a very simple process flow.

SimpleAGVFlow_fm.fsm

Re: How to instruct AGV to stay /travel to park points if there is no work

jason_lightfoot_adsk — Mon, 13 Feb 2023 09:41:58 GMT

For which you'll likely need to partition the park points list too.

Re: How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Mon, 13 Feb 2023 09:55:04 GMT

@Felix Möhlmann Your process flow logic was great and I tried implementing it to my model, and it works well, but the AGV only picks up one item, even when the pickup point contains more than one. I also tried modifying your process flow logic, but it's still just collecting one item. Can you help with this? What modifications to your logic should be made so that an AGV should pick all items that are available at a pickup location or a Q.

Re: How to instruct AGV to stay /travel to park points if there is no work

jason_lightfoot_adsk — Mon, 13 Feb 2023 10:04:30 GMT

There are many examples of this on the forum - it involves pulling more than one item from the list and using subflows to load and unload items.

Please try to implement this and come back if you get stuck.

Also - consider starting a new question when the topic changes from your initial question.

Re: How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Mon, 13 Feb 2023 13:11:50 GMT

Firstly, I apologize to @Jason Lightfoot I didn't mean to trouble you with my Question. I simply followed the discussion's natural flow,as the second issue is also connected to the AGV empty travel concept I thaught, it would be inappropriate to post a new question while the conversation is ongoing. Sorry for the inconvenience; if a new issue or query emerges, nextime I will post a new question.

Second, I tried subflows for loading and unloading as you advised in order to pick up and deliver more items. However, as the AGV picks the items, I am dealing with an issue or error below. I was unable to comprehend the mistake or its source.

Model with the issue AGV Empty Travel issue3.fsm

Can you assist me please?

Re: How to instruct AGV to stay /travel to park points if there is no work

jason_lightfoot_adsk — Mon, 13 Feb 2023 14:18:58 GMT

Felix used one token to represent the AGV and you've changed it so that you get a token generated for each item. You would either do that and batch OR pull a number of items from the list using one token - you should not need to do both.

You should set the AGV to not travel offsets for load/unload tasks.

Re: How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Mon, 13 Feb 2023 15:45:01 GMT

Hi @Jason Lightfoot

I made some change to processflow now there are no errors showing up. When i am trying to batch items ,only one item is getting pulled and the flow is freezed.

Re: How to instruct AGV to stay /travel to park points if there is no work

jason_lightfoot_adsk — Mon, 13 Feb 2023 15:54:20 GMT

If you have one token then you don't want to batch with other tokens - so remove that and use the list to pull multiple items.

Re: How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Mon, 13 Feb 2023 17:11:30 GMT

Hi @Jason Lightfoot . As you said i removed the batch activity and also used a list to pull items. Now i am addressing the below issue. If you don't mind could you show me in a sample example or in my model that where i am doing wrong. I just want to learn from my mistake

AGV Empty Travel issue3.fsm

Re: How to instruct AGV to stay /travel to park points if there is no work

jason_lightfoot_adsk — Mon, 13 Feb 2023 17:29:16 GMT

You're trying to travel to the item location but you have not read any item from the array of items yet - you do that when you call the subflow.

Re: How to instruct AGV to stay /travel to park points if there is no work

AjayManneni — Mon, 13 Feb 2023 19:29:57 GMT

@Jason Lightfoot Thank you and I really appreciate your suggestions. Even now, I'm not sure where I went wrong since every time I try to fix one mistake, another one comes up. Anyhow, I'll attempt to look for any alternative solutions to this problem.

Re: How to instruct AGV to stay /travel to park points if there is no work

jason_lightfoot_adsk — Mon, 13 Feb 2023 19:52:53 GMT

Just put the travel task in the subflow and set it to run one at a time (and turn off the offset travel)