I want to create a similar figure with Simulink like:
Figure-1
This is my MATLAB code:
n = importdata('n.txt',';')
cars = n(:,2)
trucks = n(:,3)
bus = n(:,4)
t = linspace(1,365,365)
t = transpose(t)
Here are my Simulink blocks:
Figure-2
And "Scope" block does this kind of figure:
Figure-3
Why is Simulink figure (Figure-3) not similar to Figure-1. I want to create a similar figure with Simulink. Where is the problem?
Note that the t(ime) vector that defines your input data has no effect on the length of time that the simulation runs - it purely defines the shape of your input data.
By default, the Stop Time for a Simulink model is 10 seconds, which is why your second figure only runs out to 10 seconds. Your model is only reading/simulating the first 10 seconds of data. Change the Stop Time (across the top of the model's window) to be either 365, or even better max(t). (In the latter case, if you subsequently change t in the MATLAB Workspace then the simulation stop time will change accordingly too, without you having to manually change anything in the model.)
By default the Scope will show all of the simulated data. But if it doesn't (or you zoom at any time) then you can use the zoom tools (across the top of the Scope) and various of the Scope Properties to change the amount of data you see.
Related
Is it possible to explicitly set the sample time of a Matlab function block in a Simulink model? If yes, how? If not, how can you change the sample time of a signal coming from a Matlab function block?
For instance, how can one make sure that the sample time of a (possibly variable-sized) signal coming out of a block will be discrete?
Your best option is to use the Rate Transition block.
Also have a look at the Convert Signals Between Continuous Time and Discrete Time example to see how it's being used in practice.
Using the Matlab Function block you can Right click > Block Parameters > Sample time. Change from -1 to the sample time you want.
To make sure your simulation is using the correct sample time you can select the double arrows in the left panel and click on "Colors". Then, back in the double arrows, select "Sample Time Legend". Now, the different colors represents different rates in which Simulink is running.
I have a control model in Simulink which consists of two blocks. One which takes some inputs and generates three signals, x,y,z as arrays (trajectory) and feeds them to the second block as reference for the control.
I would like to be able to run this using a recorded trajectory. I have simulated the trajectory (by running the simulation once) and written the data to a mat file (signals plus timestamp). I can remove the first block and feed the mat file to the second control block and it works fine.
The trajectory is a loop. My question is, I would like to be able to start the simulation at any point in the file and I am not familiar with how Simulink manages time. If I want to start from a different point what do I need to do and can I make it continuous so that if I start from point N-1 in the file it will proceed through N and back to 1,2,3 etc.
Thanks,
Bryan
If you want to start at a different time point you won't be able to directly use the .mat file that you have created. You'll need to load the data into MATLAB and change the time vector so that t=0 corresponds to the data that you do want to start with.
Since you want to repeat the sequence, you most likely want to use the Repeating Sequence block. This would require you to load the data into MATLAB (and do the time alignment) anyway.
Assume that you have a Simulink simulation where a certain signal is first positive and after some time t in a given interval, it becomes negative. Your goal is to find the zero-crossing.
A first approach would be to plot the signal over the given interval, save it and calculate the zero-crossing.
When repeating this simulation numerous times for varying parameters, it would be beneficial to be able to stop the simulation after the signal has become negative. Then there is already enough information for the calculation of the zero-crossing in Matlab. How could you do that?
Yes, use the Stop Simulation block with the appropriate logical input to the block:
You can use an if / else block to control the flow in the Simulink model. In the if / else block, you can choose the condition if u > 0, continue as normal if it's true, and use the else-option to bypass the rest of the flow you would otherwise run. For instance jump directly to the scope.
Another ways:
You can use Hit Crossing Block in Simulink to find time at the moment of hitting zero.
Another way - use any Trigger or Resettable system. It detects the zero crossing too. For example: this question at SO.
Of course you can also use User Defined function to detect zero crossing by your hand and do whatever you want with the signal at the same time.
About making a lot of simulations and then stops:
you can use Check Upper Static Bound for automatically stops simulation at the moment when zero will be crossed in nth time. For example:
I set upper bound = 10 for this block and this stops at 10th crossing.
There are a lot of ways to save function values in this points or just array of times but this is an another question :)
I have a system with some embedded Matlab blocks where I'd like to perform some actions after a certain amount of time, in this case turn on lights and switches in an interface to which I send signals from Simulink.
The problem is that I thought I'd use "tic"-"toc" and "while" in a Matlab function block to perform these actions, say one parameter becoming 1 after 5 seconds, the following parameter becoming 1 after 12 seconds and so on, but I noticed that tic-toc apparently doesn't work in Simulink for embedded functions.
Is there any similar functions that could be used in Simulink for embedded functions or is there any other way to do this?
Edit: I've tried to get the clock's time as well, but it's a growing value. Is there any way to "lock" the time as a parameter when the block's function is executed?
You shouldn't be using absolute time in an embedded system, which is at least one of the reasons why tic-toc and clock from MATLAB don't work with Simulink Coder.
You should create your own counter, which you start and stop when you need to.
This is pretty easy to do using a Unit Delay and Summation block.
If you need to be able to enable and/or reset the counter then use the appropriate block from the Additional Discrete library.
I'm using the simulink block From Workspace to read in some audio data provided by a script. I have formatted the data in a matrix with 2 columns, the first is the timestamp and the second is the data.
In the configuration paramaters, I have specified Fixed-Step and Discrete solver. The Start time and Stop also need to be configured manually and don't seem to come from the data.
Also, in the From Workspace block configuration, I need to specify the sample time (1/44100) or I get a warning if I specify -1, to inherit from the data and then get strange sample times.
So, how can I get simulink to use only the sample times in the matrix and use the first and last timestamps as the start and stop time of the simulation?
You should be able to do what you want by doing the following:
Firstly note that your problem is by definition not fixed step, hence you cannot use a fixed-step solver, which by definition is ... fixed-step.
You must use a variable step solver.
Assuming your (2 column) input data is called simin then set the start and stop times to be simin(1,1) and simin(end,1) respectively.
In your From Workspace block set the sample time to be 0 (which should have been the default).
Also de-select the Interpolate data option; and set "Form the output after final data value by:" to zero (you won't be using anything past the end of your data set so this should be OK.
Then you need to tell the solver to take additional steps to those that it would naturally want to take.
Do this on the Data Import/Export pane of the Model Configuration Parameters.
Near the bottom of the pane there is a selection box and an edit box for doing this.
Note however that this does not prevent the solver from taking steps at other time points, it just forces it to take additional steps at the times you specify.
But because you have your From WOrkspace block to not interpolate this shouldn't be a problem either. You should put simin(:,1) in here so that the solver is guaranteed to take steps at the time points in your input data.
Note that if you want an input block that only samples at the time points in the simin time vector then the only way to do this is to write an S-function that uses the mdlGetTimeOfNextVarHit method to tell the solver what the next sample time (for this block) should be.