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# ModelEntity Initial DesiredSpeed

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Hello,

I have a couple of questions regarding the entity speed:

1) As a default, the initial desired speed for ModelEntity is equal to  1.4 m/s.  What does it mean? does it mean that all entities have this speed before they move (When they are created)? Is it possible the speed of entity accelerates or decelerates when it enters to the link? If yes, does the entity keep the speed during the path? Also, How does the speed of an entity detect to change when an entity enters a path? Is it random (or follows distribution)? Or based on the distance with the front entity, the speed of entity change?

2) How can I calculate the speed of an entity at each unit of time? (Like Police radar detection)

Thanks,

Nadere

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As a default, the initial desired speed for ModelEntity is equal to  1.4 m/s﻿.  What does it mean?

Desired speed means maximum speed. When there is nothing restricting the entity, it'll travel at its desired speed.

If entity's desired speed is 1.4 and the path maximum speed is 2.0, the entity will travel at 1.4.

If entity's desired speed is 1.4 and the path maximum speed is 1.0, the entity will travel at 1.0.

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does it mean that all entities have this speed before they move (When they are created)?

Initial Desired Speed is a property. Every entity starts at this speed. You can change it mid-run by assigning a new value to the Desired Speed state.

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Is it possible the speed of entity accelerates or decelerates when it enters to the link?

It is a constant speed, unless you code it otherwise somehow.

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If yes, does the entity keep the speed during the path?

Yes, unless the entity is restricted by the path maximum speed or slower entities blocking the path.

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2) How can I calculate the speed of an entity at each unit of time? (Like Police radar detection)

Use the expression ModelEntity.Movement.Rate.

ModelEntity.DesiredSpeed returns the entity's current maximum speed, not that instant speed.

___________________________________________

I tried to compile all my answers in a single model. Check the file attached at my post.

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17 hours ago, GFurtado said:

Desired speed means maximum speed. When there is nothing restricting the entity, it'll travel at its desired speed.

If entity's desired speed is 1.4 and the path maximum speed is 2.0, the entity will travel at 1.4.

If entity's desired speed is 1.4 and the path maximum speed is 1.0, the entity will travel at 1.0.

Initial Desired Speed is a property. Every entity starts at this speed. You can change it mid-run by assigning a new value to the Desired Speed state.

It is a constant speed, unless you code it otherwise somehow.

Yes, unless the entity is restricted by the path maximum speed or slower entities blocking the path.

Use the expression ModelEntity.Movement.Rate.

ModelEntity.DesiredSpeed returns the entity's current maximum speed, not that instant speed.

___________________________________________

I tried to compile all my answers in a single model. Check the file attached at my post.

Hello GFurtado,

Thank you so much for replying my questions very comprehensive. In your model, you assume that the value of DesiredSpeed is equal to "random.exponential(1)+1", and then you calculated the movement.rate. I change the following parameters in the attached file, and I have one more question about the "Movement.Rate".

1) Instead of considering "exponential(1)+1" for ModelEntity.DesiredSpeed on State Assignment, I consider the constant value 3 m/s.

2) Also, I add one more source to the model to create congestion on the model (Source 2 has a similar property with Source 1) .

When I run the model, "RadarDetectedSpeed" shows the constant number "10800", however, we have congestion. Does it mean that the speed of entities are fixed even we have congestion on the road? I expect that the Movement.Rate shows a larger number on "RadarDetectedSpeed" because speed = (difference distance/difference time), since we have 1) congestion on the road, it takes more time to stay on the road 2) fixed speed, the difference distance should be larger.

Thanks,

Nadere

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That might sound counterintuitive, but entities are alternating between 0.0 and 3.0 m/s in a discreet manner. They don't have acceleration or deceleration.

They are not slower, they are full-stopping before entering the node.

(Difference distance/diference time) = average speed.

Movement.Rate returns that instant speed, which are either 0.0 (full stop) or 3.0 (desired speed). You can verify this by looking at the label attached to the entity.

I'm not experienced enough in Simio to help you creating an entity capable of smoothly decelerate, but you could calculate the average speed between two nodes (check the attached model).

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Hello GFurtado,

Thank you very much for helping me. I have one more question related to the acceleration. As far as I know, we can accelerate the speed of entity in free space. I want to modify the previous file by adding another path after checkpoint2. Therefore, the congestion will be decreasing on path5 and path3. Is there any way to accelerate the speed of entities on path 5 and 3? If yes, could you please help me how I can do it?

Thanks,

Nadere

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