Hi,

We have developed a parallel framework over SUMO. When I am copying
vehicles from one partition to another. With the vehicles I am also copying
the following lane change parameters. I am keeping sigma 0, --random false
and same seed value for all the partitions and sequential SUMO.

"laneChangeModel.speedGainProbabilityRight"
"laneChangeModel.keepRightProbability"
"laneChangeModel.lookAheadSpeed"

After adding vehicles in the next partition, I am also moving them for the
desired position in the current step and setting speed for the current
step.
i am calculating the current step speed as follows:

double vthis=LastTimestepSpeed+ACCEL2SPEED(LastTimestepAcceleration);
Or if the vehicle has a Leader...then with the follow speed.

But if I compare travel time of this parallel framework with sequential
SUMO, I am getting an accuracy error.

I have found that patchSpeedBeforeLC is calculating some different speed
which is causing randomness.

  vDawdle = MAX2(vMin, dawdle2(vMax, sigma, veh->getRNG()));

This randomness calculation should be off when we use --random false.

Thanks,
Mahima

On Wed, Feb 22, 2023 at 1:41 PM Jakob Erdmann <[email protected]> wrote:

> The function getStopSpeed is not only used for <stop> elements but also
> for approaching intersections where a vehicle needs to come to a stop.
> From your description it is not clear what exactly you are doing and why
> you are observing a differences between some speeds and some other speeds.
>
>
> Am Di., 21. Feb. 2023 um 14:24 Uhr schrieb Mahima <[email protected]>:
>
>> Thanks for your reply.
>> Yes, sigma is already set as 0. The only difference I can see is the stop
>> speed (getStopSpeed) is different.
>>
>> How can I set the stop speed of a vehicle? Is it by using
>> libsumo::Vehicle::setStopParameter? But then I need to define the stop
>> first...correct?
>>
>> Thanks.
>>
>> On Sun, Feb 19, 2023 at 3:28 PM Jakob Erdmann <[email protected]>
>> wrote:
>>
>>> > Why does the vehicle need information about the vehicle on the
>>> previous edge for the car following model speed calculation?
>>> This is likely a misunderstanding. What gives you that impression?
>>>
>>> > How can I set the car following model parameters from the previous
>>> partition to the master partition such that it gives the same speed
>>> calculation of a vehicle?
>>> The default car-following model doesn't have internal state so it should
>>> reproduce the same behavior when faced with the same situation (distance,
>>> ego speed, leader speed, deceleration capabilities, speedFactor). A
>>> possible cause for difference is the random component (sigma). You can
>>> check whether the differences are due to randomness by setting sigma=0.
>>>
>>> Am So., 19. Feb. 2023 um 11:36 Uhr schrieb Mahima <[email protected]>:
>>>
>>>> Hi,
>>>>
>>>> Why does the vehicle need information about the vehicle on the previous
>>>> edge for the car following model speed calculation?
>>>> How can I set the car following model parameters from the previous
>>>> partition to the master partition such that it gives the same speed
>>>> calculation of a vehicle?
>>>>
>>>> Thanks
>>>>
>>>> On Wed, Sep 28, 2022 at 9:48 AM Jakob Erdmann <[email protected]>
>>>> wrote:
>>>>
>>>>> using getParameter / setParameter with the following values should be
>>>>> enough for the default lanechangem model:
>>>>> "laneChangeModel.speedGainProbabilityRight"
>>>>> "laneChangeModel.keepRightProbability"
>>>>> "laneChangeModel.lookAheadSpeed"
>>>>>
>>>>> Am Mo., 26. Sept. 2022 um 09:58 Uhr schrieb Mahima <[email protected]
>>>>> >:
>>>>>
>>>>>> When I am copying a vehicle from one partition to the other on the
>>>>>> same lane and position as it was on the previous partition, but in the
>>>>>> current timestep if there was a lane change decision in the previous
>>>>>> partition......which lane change API or flag will give me the same lane
>>>>>> change decision in the master partition.
>>>>>> In this scenario, I am already making sure that the neighbouring
>>>>>> vehicles for this vehicle are the same as on the previous partition.
>>>>>>
>>>>>> Please suggest.
>>>>>>
>>>>>> On Mon, Sep 26, 2022 at 9:39 AM Jakob Erdmann <[email protected]>
>>>>>> wrote:
>>>>>>
>>>>>>> No. TraCI runs before the computation of this step's values (
>>>>>>> https://sumo.dlr.de/docs/Developer/Implementation_Notes/Simulation_Loop.html#main_vehicle_update_loop
>>>>>>> )
>>>>>>>
>>>>>>> Am So., 25. Sept. 2022 um 11:02 Uhr schrieb Mahima <
>>>>>>> [email protected]>:
>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> Is there any way to read the vehicle's speed, lane and position in
>>>>>>>> the current timestep?
>>>>>>>>
>>>>>>>> libsumo::Vehicle::getLanePosition
>>>>>>>> libsumo::Vehicle::getSpeed
>>>>>>>> All these APIs, give information about the last timestep.
>>>>>>>>
>>>>>>>> Thanks
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