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eclipse-sumo / sumo

Eclipse SUMO is an open source, highly portable, microscopic and continuous traffic simulation package designed to handle large networks. It allows for intermodal simulation including pedestrians and comes with a large set of tools for scenario creation.
https://eclipse.dev/sumo
Eclipse Public License 2.0
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Query about "MinGap" and "Dynamic Spacing Margin" #15237

Open 1010617348 opened 2 months ago

1010617348 commented 2 months ago

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If possible, upload an example that shows your problem.

**SUMO-version:1.20.0

**operating system:Windows 10

When vehicles are queuing up, I have noticed that the gap maintained by ACC and CACC to the front vehicle always does not match the set “MinGap” and the gap changes with the type of front vehicle. Is this caused by the "Dynamic Spacing Margin"? If so, is there a way to disable the "Dynamic Spacing Margin" control?

<routes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://sumo.dlr.de/xsd/routes_file.xsd">
    <!-- VTypes -->
    <vType id="cav" maxSpeed="33.33" desiredMaxSpeed="33.33" length="5" tau="0.6" accel="1" decel="2" minGap="2" carFollowModel="CACC" color="blue" />
    <vType id="hdv" maxSpeed="33.33" desiredMaxSpeed="33.33" length="5" tau="1.5" accel="1" decel="2" minGap="2" carFollowModel="IDM" color="yellow"/>
     <vType id="av" maxSpeed="33.33" desiredMaxSpeed="33.33" length="5" tau="1.5" accel="1" decel="2" minGap="2" carFollowModel="ACC" color="red"/>

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namdre commented 2 months ago

@robertalms ?

robertalms commented 2 months ago

Hi @1010617348, I think you asked a fairly similar question in #13920.

  1. For the ACC, yes, the increased gap at standstill comes from the dynamic spacing margin. I don't see the need to add an extra option for deactivating it to SUMO in general, because it solves a lot of issues with the standstill behavior. (But maybe @namdre has a different view on that?)

Would it be an option for you to simply set the d0 = 0 in line 177 of the ACC and compile SUMO locally yourself?: https://github.com/eclipse-sumo/sumo/blob/d313ef5340596673194e97d50f39f8d1b8f19310/src/microsim/cfmodels/MSCFModel_ACC.cpp#L177

  1. I'm not sure the spacing margin is even implemented or tested for the CACC.

  2. Regarding the different gaps based on vTypes: That seems to be the case only for CACC. The CACC is designed for connected platooning, therefore vehicles of the similar vType CACC allow for smaller gaps, whereas gaps to different, non-connected vTypes are larger.

Again, the standstill/approaching behavior of the ACC/CACC is not solidly validated, and the minGap concept of SUMO is not necessarily considered in those models. Due to limited resources, we haven't explored these issues further, but help is always welcome. ;)

1010617348 commented 2 months ago

Thank you for your reply and attention. I observe that the param "caccVehicleMode" will change from "CC" to “ACC” when CACC follows non-CACC. I would like to know how the gap control is carried out (literatures, codes or rules) after the “caccVehicleMode” change. Because unlike ACC, the gap (gap to front vehicle if halting) of CACC following other types of vehicles seems to be irregular?

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