Run two co-simulation FMUs at a time step using the same states but different inputs

Question

I am trying to run an FMU for a nominal input and at the same time step for a perturbed input using the same states as the original FMU.

The main difficulty here is making a copy of the FMU i.e. saving the numerical data and setting it again in an FMU.

At the moment, I have been working with fmpy and this package does have several functionalities for saving and setting the states. However, none of these are supported by the FMU that I am working with at the moment. So I would need to look if there is another way around this to access to numerical data.

Additionally, I tried the CancelStep functionality to try to reset the states of the FMU, but this provided an 'error 3' output.

from fmpy import *

from fmpy.fmi2 import FMU2Slave



fmu_filename = 'BouncingBall.fmu'



Ts = 0.01



# load fmu

model_description = read_model_description(fmu_filename)

vrs = {}

for variable in model_description.modelVariables:

    vrs[variable.name] = variable.valueReference



v = vrs['v']

y = vrs['h']



unzipdir = extract(fmu_filename)

fmu = FMU2Slave(guid=model_description.guid,

                unzipDirectory=unzipdir,

                modelIdentifier='BouncingBall',

                instanceName='instance1')



fmu.instantiate()

fmu.setupExperiment(startTime=0.)

fmu.enterInitializationMode()

fmu.exitInitializationMode()



v_t0 = 0

y_t0 = 2

dv = 0.1



fmu.setReal([v], [v_t0])

fmu.setReal([y], [y_t0])



fmu.doStep(currentCommunicationPoint=0., communicationStepSize=Ts)

print(fmu.getReal([y]))

print(fmu.getReal([v]))



fmu.cancelStep()



fmu.setReal([v], [v_t0 + dv])



fmu.doStep(currentCommunicationPoint=0., communicationStepSize=Ts)

print(fmu.getReal([y]))

print(fmu.getReal([v]))