How can I get a simulink model to execute in real-time?

I'm trying to get a Simulink model of a quadrotor and controller to accept inputs and run at real-time speed. My goal is to have this low-level controller interface with a higher level controller in Python

Answer 1

[Walter Roberson]

Simulink Real Time execution requires generating code . There is no way to talk to Python unless it is on a different system, or unless Python can be called as C or C++ that is able to run with the destination Real Time Operating System.

An alternative to Simulink Real Time is Simulink Coder which can generate C or C++ code that can be compiled for any target, possibly hosted (that is, has an operating system.) The ability to run in Real Time on a hosted target would depend upon the facilities provided by the host operating system; for example you can do it with some Linux and Linux-like operating systems, but it is problematic with MS Windows, which thinks it should be able to (for example) defragment your terabyte disk drives in the middle of patient surgery.

[Ryan]

Code generation wouldn't be a problem, except I'm doing some quaternion algebra with functions that do not support code generation. I guess the workaround for this is to use quaternion operators written in C/C++?

To clarify the python situation, that program is executing in a separate process and communicates with Matlab over UDP. It is also responsible for transmitting the location and orientation of the vehicle to a separate simulation running remotely. One of the other issues I was running into was crappy UDP in Simulink vs. relatively flawless UDP when being called from a .m script.

Another possibility I was thinking of was as follows. I'm able to call a bash script from the Python side which starts Matlab in headless mode and executes a script that runs the Simulink model with inputs. Proceeding this way I could run a 5 second simulation that executes in say 2-3 seconds, take the resultant time and solution vectors and use python to send these out to the external simulation as if they were occurring in real-time, but this just seems like a big hack to me.

My motion capture system has to run on Windows (bleh) but I could run the quadrotor sim on OS X where the Python code is running. As much as I would prefer the latter option, from a latency perspective I would probably be better off running the quad sim on the Windows box as well.

I appreciate any other feedback you might provide on this.

Answer 2

[Bo Li]

Regarding the communication from Python to MATLAB, you may consider Python Engine:

http://www.mathworks.com/help/matlab/matlab-engine-for-python.html

This feature was introduced in R2014b.

[Ryan]

Very good, thanks for the reminder. I had been working on R2014a, but recently got set up with our R2015a license so I can use this instead of that bash rigamarole.

[Alma Martinez]

Hi, you can send data from python to matlab?, Using a 'communication in real time?, is it possible with python engine or another tool?