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zenos paradox when approaching a stop with subsecond simulation (trac #2310) #2310

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behrisch opened this issue May 9, 2016 · 4 comments

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@behrisch
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commented May 9, 2016

The issue is closely related to #2186
Effectively, vehicles compute the speed for approaching a stop under the assumption of maintaining that speed for tau seconds. However, by updating the speed earlier the approach speed is successively lowered and the stop is not reached (except for using tricks)

Migrated from http://sumo.dlr.de/ticket/2310

{
    "status": "new", 
    "changetime": "2016-07-26T10:36:56Z", 
    "description": "The issue is closely related to #2186\nEffectively, vehicles compute the speed for approaching a stop under the assumption of maintaining that speed for tau seconds. However, by updating the speed earlier the approach speed is successively lowered and the stop is not reached (except for using tricks)", 
    "reporter": "namdre", 
    "cc": "", 
    "resolution": "", 
    "_ts": "1469529416461255", 
    "component": "microsim - car following", 
    "summary": "zenos paradox when approaching a stop with subsecond simulation", 
    "priority": "major", 
    "keywords": "", 
    "time": "2016-05-09T13:40:33Z", 
    "milestone": "1.0.0", 
    "owner": "", 
    "type": "defect"
}
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commented May 9, 2016

@namdre committed 683fe93 (aka r20680):
alternative fix #1224, fix #1864, added workarounds refs #2310

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commented May 9, 2016

This should be fixed by changing the way, in which the Krauss-related cf-models (all that use safeStopSpeed() determine the stopping speed when approaching a stop.

Currently this is done taking into account the desired time-headway, such that at every moment the vehicle keeps a temporal distance of myHeadway to the stopping point leading to the reported creeping approach.

This seemingly originates in that the maximumSafeStopSpeed() method was primarily implemented as a heuristic to determine the maximal safe following speed in maximumSafeFollowSpeed().

I think one could do a quick fix by giving maximumSafeStopSpeed() a flag whether it is called in a car-following situation or not.
(Although I can imagine that reacting in a different way to a stopped vehicle as to an intended stopping position can lead to unnatural behavior in some rare situations)

to:

1463122728633241

This should be fixed by changing the way, in which the Krauss-related cf-models (all that use safeStopSpeed() determine the stopping speed when approaching a stop.

Currently this is done taking into account the desired time-headway, such that at every moment the vehicle keeps a temporal distance of myHeadway to the stopping point leading to the reported creeping approach.

This seemingly originates in that the maximumSafeStopSpeed() method was primarily implemented as a heuristic to determine the maximal safe following speed in maximumSafeFollowSpeed().

I think one could do a quick fix by giving maximumSafeStopSpeed() a flag whether it is called in a car-following situation or not.

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commented May 9, 2016

@namdre commented:

the cleanest solution would be to use models that determine safe acceleration rather than safe velocity.

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commented May 9, 2016

@namdre changed milestone from "0.28.0" to "1.0.0"

@behrisch behrisch added this to the 1.0.0 milestone Oct 28, 2017

@behrisch behrisch added bug and removed bug labels Oct 29, 2017

@namdre namdre modified the milestones: 1.0.0, 1.1.0 Aug 29, 2018

@namdre namdre closed this in c5012f3 Nov 19, 2018

namdre added a commit that referenced this issue Nov 19, 2018
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