How to iterate over values of models in Simulink Matlab? - matlab

I have designed a model in simulink. Generally, I generate a plot by setting the values of blocks(eg.gain) in the model and simulating the model and opening the scope block. But I need to generate different grpahs corresponding to different values of blocks(eg.gain). Basically, for different values of Gain value, I want different graphs but all in the same plot. The different values I give to my gain should be from an array. This is my model
I am using MATLAB for the first time. Please answer this in a beginner's approach

Setting The Gain Value
The values of the gain blocks can be can be set as variables rather than constants i.e. you can give a gain block the value of K in the settings panel.
You can then create a script that gives K a value e.g;
%script to set gain and run model
K=2;
sim('Model Name Here');
This will set the value for your gain block and run the model.
Saving The Output
In the sinks section of the simulink library browser is a block called To Workspace, this allows you to send any output value to the MATLAB workspace in multiple formats with a name that you define.
Your simulink model will now look something like this;
Now you can create a script that sets a gain value for your model, runs the model and saves the output to your workspace. With a couple of for loops and you can produce an array of inputs and outputs for your system.
From here you should be able to plot the inputs and outputs on the same graph using the well documented plot function.

Related

How to load non timeseries data into simulink for use in a deep neural network

I trained a neural network in python and want to load the weights into simulink to pass into a function that will build the network. I thought I could use from workspace but it seems it does not handle non time series data for a structure. I get the error.
Invalid structure-format variable specified as workspace input in 'PMSM_FCS_MPC/From Workspace'. If
the input signal is a bus signal, the variable must be a structure of MATLAB timeseries objects.
Otherwise, the variable must include 'time' and 'signals' fields, and the 'signals' field must be a
structure with a 'values' field.
How can I pass a bunch of arrays into a simulink function?
Everything I have seen is about time series data. Nothing on a group of matrices such as would be used in a deep neural network.
The From Workspace block is designed to work with time-series data (as per the error message you show.) There is no need to use it if you have constant data.
If you have non-time series data and you need it as a Simulink signal then use the name of the MATLAB variable as the parameter in a Constant block. The signal coming out of the block will have the value of your data.
If you are using a MATLAB Function block then you can also input the data as a parameter argument to the function. See Add Parameter Arguments for the steps to do this.
Not sure how you want to use the data. But if you have those weights as an array in the main workspace, you can simply reference to that variable in Simulink. For example if you have K = [1 2] in your workspace, you can use any block and type in K(1) or K(2). You can do also matrix operations and gather signals with Mux block.

Heterogeneous data from workspace into Simulink

I have different matrices to import into a Simulink Matlab function from the workspace. These matrices have all different dimension, which I don´t know at priori.
At the beginning I tried using the block 'constant' putting the data all together in a structure like this:
But then, I cannot pick the right matrix since I don´t know the dimension of each element (and also 'mux' cannot be used to split matrices).
I think I will have the same problem also with the block 'from workspace'.
I was wondering if there is a smart way to import heterogeneous structures like these. I tried also with cell-arrays, but it seems to be not supported by Simulink.
Thanks for any suggestions.
If the data is to be used in a Matlab Function block you could define the workspace matricies as parameters in the model explorer and in the Matlab Function port editor. You then have them accessible inside that function without even needing the "const" blocks or drawing any signals.
Even if your final intent is not to have data into a Matlab Function block those blocks are quite useful for extracting signals from heterogeneous data since you can do some size/type checking in them. Then you can output "simulink friendly" signals for use elsewhere.

Iterate over array from workspace at each sample time in Simulink MATLAB function block

I have a MATLAB function block embedded in a Simulink model. In my initFnc callback I set up some vectors which I need to use in my function block inside the simulink model. The vector is 1x10000 and contains setpoints for a robotic arm. The function block simply needs to read the next value at each sample iteration.
So far I've tried using "From Workspace" and "evalin()" but they all throw various errors when building the model (I'm using code generation which doesn't play nice all the time).
What would be a good way to read in that vector in Simulink and feed the cells one by one into my function block? Something like repeating sequence stair but without the repeating part.
I got it to work by reading in the vector into a constant block and feeding that into my embedded function. I then use a persistent iterator which is a 1x1 matrix (ones(1)) and incrementing it every time the value from the vector is read.

Run a continuous Simulink model with real-time input?

I'm new to Matlab/Simulink but have a requirement to interface with a Simulink model from a piece of software.
At the moment I have created a simple Simulink function 'Inc' which has 1 input to an addition block with a constant 1 and an output. I have used To/From Workspace blocks and can run the simulation over a fixed time using a time/value vector input, such as simin = [0,0;5,0;5,1;10,1].
What I would like to do is run my model continuously? Reading Workspace values in real-time rather than a pre-defined time based vector?
I can't see how to set this up? Can Matlab/Simulink do this?
To summarise, I would like simin and simout to be single values i.e. simin = 1, then with the model running continuously(infinitely) at the next fixed step simout would update to simout = 2. simin changes would be made at the Workspace at varying intervals.
The short answer is you can't (easily) do that, that's not how Simulink works. The MATLAB workspace is read/accessed at the beginning of the simulation and passed to the Simulink engine, and even if the values in the workspace change before the simulation is finished, this is not taken into account by the Simulink model running.
There are ways to work around this, but if you are a novice to MATLAB & Simulink, be aware that these are fairly advanced techniques, and I would advise to familiarise yourself with Simulink first.
Have a look at these similar questions for suggestions of how to do what you want:
Stream data form MATLAB to Simulink
Problem of variable updating in workspace
How Do I Change a Block Parameter Based on the Output of Another Block?
Tuning block parameters at every time step in a simulation
Simulink Signal Viewing using Event Listeners and a MATLAB UI
Obviously, you need to change the simulation end time to Inf or some large number.

Dense output of SimMechanics?

I have set up a model using SimMechanics. It outputs data at the times where the solver steps to. Is there any possibility to have some kind of dense output such that it is possible to interpolate these data to get the solution at arbitrary points without losing the high order of the integrator?
In Matlab this is easily possible using the function deval after the integration of one of the built-in ODE integrators.
In SimMechanics I can select these integrators, too. Is there some kind of analouge way to deval?
Yes, it's possible, although it's a Simulink functionality, not specific to SimMechanics. In the Configuration Parameters of the model, you can set the model to Produce Specified Output Only (see http://www.mathworks.co.uk/help/simulink/gui/data-import-export-pane.html#bq9_fhw-1), under Data Import/Export. This way, only the outputs you specify will be produced regardless of the time steps taken by the solver.