well, i might be not clear enough.
Here is a script that i wrote to handle this problem, but i would like to plug that directly in the model and not in a script

n=readTrajectorySize("dsres.mat"); // find the length of the simulation results vectors

traj_mass1=transpose(readTrajectory("dsres.mat",{"massWithStopAndFriction.s"},n));  //extract the mass one trajectory

traj_mass2=transpose(readTrajectory("dsres.mat",{"massWithStopAndFriction1.s"},n)); //extract the mass two trajectory

traj_Vmass1=transpose(readTrajectory("dsres.mat",{"massWithStopAndFriction.der(s)"},n)); //transpose tranformation

traj_Vmass2=transpose(readTrajectory("dsres.mat",{"massWithStopAndFriction1.der(s)"},n)); //transpose tranformation



// creation of a vector of 500 points

pos=fill(0,500,1);



//creation of a [500,3] matrix 

vitessFpos=fill(0,500,3); 



// I want to have a point pro millimeter (the masses move from 0 to 0.5m)

pos[:,1]=1:500;

 pos[:,1]=0.001*pos[:,1]; 



//loop to find the index in trajectory mass vector where the mass  step from 1 mm

indexref=fill(0,500,2);

for i in 1:500 loop

    for j in 1:n loop

    

        if traj_mass1[j,1]-pos[i,1]<=0.0001 then

            indexref[i,1]=j;

        else

        end if;

        if traj_mass2[j,1]-pos[i,1]<=0.0001 then

            indexref[i,2]=j;

        else

        end if;

    end for;

end for;



vitessFpos[:,1]=pos[:,1]; //copy the first column of the position vector (it's the reference position vecotr)



// loop to find the velocity value in the velocity vector the point where we step from one millimeter to an other



for i in 1:500 loop



    vitessFpos[i,2]=traj_Vmass1[indexref[i,1],1]; 

    vitessFpos[i,3]=traj_Vmass2[indexref[i,2],1];

end for;



plotArrays(vitessFpos[:,1], vitessFpos[:,2:3]); // plot the result Velocities of the both masses against the absolut position

Hi modelers,

I'm facing a problem when i want to plot two simulation results against a reference variable:

Let's say that i've got 2 instantiations of the same model. The model describe a translating mass, driving by a motor. The difference between them are the parameter's values and in each model.

I would like to plot the motor torque against the mass-posistion. The problem is that, the Mass-position is function of the respective "model time" or "model integration step" (actually i don't know). Which means that :
- if one mass is faster than the other and if i plot the both torque variables against position( from Mass1 or Mass2) i will not have the same plot-result.

But, the path is the same for the both mass, so why isn't it an absolut reference for the both model?! What should i do to cancel this effect, any help will be really appreciate.

------------
if i summarize :

i have :
Torque_motor1=Function(Position_Mass1)
Torque_motor2=Function(Position_Mass1)
or
Torque_motor1=Function(Position_Mass2)
Torque_motor2=Function(Position_Mass2)

i want :

Torque_motor1=Function(Position)
Torque_motor2=Function(Position)

thanks

i changed the solver and now use the Euler solver, with this solver the problem is fixed. I mean that the results are corrects.

thank you for your help.

thom

sorry, I didn't check the images.

For the OMC version, I just download this release : OpenModelica-1.7.0-revision-8711.msi


OpenMolica model : (plz take a look at the begining of the movement of the inertia)

20sim model:

OM simulation results :

20sim simulation results :

Did you mean that in Dymola, when you try to move a Inertia with a positif Torque, at the beginning of the movement the speed is negative as well as the position ?

I m sorry but i dont consider this result as normal...

Try to move a pen clockwise with your finger, and look if it s go countercloclwise... i don't think it will.

I'm modeling a motor: as a torque source, a bearing friction (rotational), an ideal gear and an inertia. The torque source is control with a sinus source.
By looking the result of the simulation in OMEdit, i was skeptic, in fact at the begining of the simulation, the sinus source is positif and rises to 2 (is maximal amplitude) but the rotational speed and the position of the inertia are, during the transition phase, Negatives !

Then I try with 20sim, wich is an other physical modeling software. With the same parameters and same components, the simulation results are differents. In 20sim the results are corrects because there is no negative values for the rotationnal speed and position.

Parameters :

- sinus : freq 1Hz, Amp : 2 (if =1  : problem)
- bearing friction : [0,1], peak : 0.5
- ideal gear : ratio = 10
- inertia = 0.001

Here are screenshots from my models and their respective results.
OpenModelica model :
imagik.fr

20sim model :
imagik.fr

OpenModelica simulation results :
imagik.fr

20sim simulation results :
imagik.fr


could anyone explain me why is there a différence ? what need i do to avoid that ?
Is there any problems with OMC ?

I've got other problems :
- if the torque source is not enough "powered" (amplitud from the sinus source = 1 ), OMEdit stay in a loop : ...\OpenModelica\tmp\OMEdit\ NameOfMyModel_res becomes bigger but i never get my results... Is there no watch dog for this kind of issue?

that the results with 20sim for sinus.Amplitude = 1
imagik.fr

I forget to say, I m working with OpenModelica 1.7.0 on a windows XP pro 64bits


kind regards
Thomas