How to execute a simulink simulation stepwise from python without a display?

I have a .slx file with a simulink simulation that i run from python code. I need to execute it step-wise and adjust parameters after each step.

My code is executed on a server to which i have remote access via SSH. The goal is to execute multiple variants of the simulation in parallel and disconnect from the server while the simulations are executed.

The 'set_param' command can not be used for this due to having no display. According to https://de.mathworks.com/help/simulink/slref/set_param.html the 'sim' command should be used in this case. While

sim_out = eng.sim('simulation_name')

works fine and returns the desired values it dows not work with

sim_out = eng.sim('simulation_name','StartTime','0.0','StopTime','10.0')

which would be needed for a stepwise execution. Or rather: I can execute it, but the return value is an empty array of shape (1,1,0).

I noticed that the second command works perfectly fine when put into the matlab command prompt instead of executing it via python.

My aim is to have something as following:

import matlab.engine as me

eng = me.start_matlab('-nodesktop -nosplash -nodisplay')
step_size = 10.0
steps = 1500
for i in steps:
    action = get_action(state)
    sim_out = sim('simulation_name','Action',str(action),'StartTime',str(i * step_size),'StopTime',str((i+1) * step_size))
    state = np.array(eng.workspace['State'])
end

Answer 1

[Anjaneyulu Bairi]

I understand that you are trying to execute the Simulink model in stepwise manner. Refer the below MATLAB Answer which solves your query.

• https://www.mathworks.com/matlabcentral/answers/827350-how-to-run-simulation-for-certain-amount-of-time.

Additionally, refer the below link which explains how to control execution of Simulink model in python.

• https://medium.com/@soutrikbandyopadhyay/controlling-a-simulink-model-by-a-python-controller-2b67bde744ee

Hope the provided information helps in resolving your query.