I have a working MATLAB program hooked up to an Arduino and rotary sensor that displays the current angle. I would like to display this angle on a Simulink model, so I can control a motor based off the current angle. Is there any way to do this without creating an angle sensor in Simulink and just using my MATLAB code that already works?
Your question is not really clear and it depends if you are trying to do it before simulation or during simulation.
If you want to do it before the simulation, just create a constant block with a variable name that is taken from the workspace, and let your function to set that variable in the workspace.
If you want to do it during simulation, it is a little more difficult but still possible. Lets create a sample a MVCE. The simulink model mask.slx contains a constant the is set to 0, and this constant value is displayed in the display block on the right. The simulation time is set to inf, so when you play it, you must stop it manually.
It is possible to checge the value of the constant while the simulation is running using this simple Matlab call:
set_param('mask/Value_to_set', 'Value', '10')
you should also consider that the constanta must be a Tunable gain (it is by default).
(as you can see the simulation is running).
There are some additional (and surely better) solution you can use:
Include your Matlab function in a MATLAB User Defined Function block, and call it at each simulation iteration. If you have compilation issue you shall follow the coder.extrinsic way (here an example for fmincon)
Use the Simulink Support Package for Arduino Uno Hardware Add-on that is available in the Add on store.
Related
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.
Assume that you have a Simulink simulation. You run it twice and consider a plot of a certain signal in time. Is it possible that there are small differences between the two signals?
A possible cause could be a variable-step solver.
Assuming all simulation parameters are the same between runs, if your simulation is complex, and uses custom blocks, such a thing is possible, if there is a bug in the initialization code.
With S-Functions, for example, you can chose if and how to reset internal state between simulation runs. With C code, it is easy enough to forget to reset something altogether, and end up with some uninitialized variable that contains garbage.
Another possibility is that something gets written into the workspace from the simulation, and is fed back into the simulation when it is initialized the next time.
I have a system with a Model Predictive Controller and PID Controller.
Assuming I have models for each controller and can express them in discrete time, please how do I integrate them together to simulate properties of the system in matlab?
Thanks
... continuing from the comments.
This is what Simulink is made for. Of course there are ways to do it without Simulink, but often you still use Simulink tools and functions just without the graphical Interface.
I assume you have your transfer functions "on paper". So you need the tf function to define your system model.
G = tf(num,den)
num and den are the coefficient vectors of your transfer function of numerator and denumerator. In Simulink you use the Transfer Fcn block and you define it with
G.num{1} %Numerator coefficients
G.den{1} %Denumerator coefficients
Your PID-controller cannot be defined using this block, as Simulink requires a higher or equal order for the denumerator. Instead use the PID controller Block. You need to calculate the Proportional, Integral and Differential gain before.
Then read the documentation about the MPC toolbox - I'm not familiar with it and can't help you on that - it is explained how you can create an mpc object regarding all your constraints (see your other question).
Then you have various options to transform your mpc object into something Simulink can deal with. I'd recommend the ss - the state space model - which can be implemented using the state space block. There is also a MPC Controller block, I don't have the toolbox - but you'll be able to find out how it can be used.
Finally you find source blocks, like a step to generate a test signal. And there are Sinks, in the easiest case scope to display your results. You can also save them to workspace or whatever...
I'm trying to solve a problem of simulating in real time in Simulink (This is solved) but plotting (real time) in Matlab ?
Details:
I want to be able to run a Simulink simulation (which is running in real time) and be able to turn on / off manual switches while the simulation is happening. This works well when I'm using the built in Scopes in Simulink but now I want to export that data to Matlab in real time as well (To make a custom looking graph).
So is there a way, to export this data (it can be sampled if that is necessary) to Matlab and make a plot that is constantly updating. Meanwhile I can still manipulate the switches in Simulink and influence the simulation manually ?
Simulink is effectively running continuously until I stop it.
Thanks for the help!
There should be some kind of notification going when simulink updates the data to be visualized. Maybe this is the linkdata feature.
Another, worse, solution is the drawnow command to redraw the graphs continously (the latter could be unnescessary costly for you program).
I'm running a SimEvents simulation using Variable-step discrete solver. I save a signal data using a 'to Workspace' block, but the plot that I obtain is different from the one shown in the 'Scope' block inside the model.
The original signal remains constant between t=64[h] and t=65.4[h] (and this seems to be correctly done also in the matlab plot), while elsewhere it is like the plot command and the 'scope' block are working with different "sample times".
I'd like to obtain a plot showing the typical "step shape" of a discrete signal rather than a "nearly continuous" signal.
I've used the Scope 'save data to workspace' as well, but I didn't solve the problem.
I would have attached some screenshots in order to make the question more complete, but this is my first question so I have not enough reputation to post images. If you need, I can send them to you via e-mail.
Thank you in advance!
There are no screenshots to look at, but my guess would be that the signal is discrete, and the Simulink scope block, knowing this, is only changing at the discrete time points.
However, if you are plotting the data dumped to MATLAB using the standard plot function then it treats the data as continuous and joins successive points with a (non-constant) line.
If that's the case, you most likely want to be using the stairs function to do your MATLAB plottig.