AGV - Allocation event

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Emmanuel VS asked Dec 6, '21 Emmanuel VS commented Dec 9, '21

AGV - Allocation event

Hi everyone. Working with control points (AGV) I have noticed that the 'allocation event’ is executed at different moments/locations (not necessarily in the previous 'control point') when the TaskExecuter speed is increased in AGV network properties. This only happens when both straight and curved speeds are changed (≥2) and the deceleration is kept at 1.

As both speeds are increased (keeping the deceleration at 1) the 'allocated' event is executed earlier. The attached model shows the mentioned situation.

That being said, is there a relationship between the control point’s 'allocation event’ and the speed/deceleration properties of the TaskExecuter? Are there speed/deceleration limitations in the use of the AGV network?

Thanks in advance for the help

Demo_AGV_controlpoints_v2.fsm

Software Version:

FlexSim 21.2.4

agv agv allocation agvnetworks

demo-agv-controlpoints-v2.fsm (54.5 KiB)

Answer 1 · 2021-12-08T18:02:38Z

anthony.johnson answered Dec 8, '21 Emmanuel VS commented Dec 9, '21

When an AGV performs its lookahead allocation, it must provide enough time to come to a stop if the allocation fails. This is why AGVs will allocate ahead when they "pre-arrive" at a control point, instead of when they are fully at the control point. Max speed and deceleration can affect this "pre-arrival" time.

Say, for example, an AGV has allocated and is traveling to CP1, and wants to continue to CP2. If, when it arrives at CP1, it cannot allocate CP2 (CP2 is allocated by another AGV), it must decelerate to stop at CP1. Let's say, for example, it is traveling at 1 m/s, with a deceleration of 1 m/s/s. Here it will travel 0.5 meters in decelerating to stop. Thus it must allocate ahead to CP2 when it is 0.5 meters short of CP1. By doing this, if it fails to allocate ahead to CP2, it can still decelerate to stop before passing CP1.

The deceleration you set on an AGV will significantly affect this "pre-arrival" distance. Decelerations that are very small will cause AGVs to perform their lookahead allocations long before they arrive at control points. This is by design.

In your case, you've set the max speed to 10 with deceleration 1. The AGV is able to hit about 6 m/s before it needs to decelerate to stop at CP12. In decelerating to a stop, it would take 6 seconds, and travel ~6*3 = 18 meters. Thus it needs to allocate ahead about 18 meters before it arrives at CP12.

· 1

Emmanuel VS commented · Dec 09, 2021 at 03:08 PM

Hello Antonhy, thanks for the detailed answer, it was very helpful to better understand the allocation event.

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