i'm working with Simulink (Matlab) and I have a problem:
I start a simulation and every 'T' time I need to stop it, save the state of the system as Simstate, and then restore the system state by changing a few variables. For example, I am working with the base model 'Inverted Pendulum with Animation' (penddemo.mdl), and when I restore the state I must change the mass of the pendulum, here's some code:
set_param('penddemo','LoadInitialState','on','InitialState','init_state'); % load the initial state
set_param('penddemo','SaveFinalState','on','FinalStateName', 'xFinal','SaveCompleteFinalSimState', 'on'); % save the complete simstate
set_param('penddemo/Pendulum','Mcart','0.600'); % change the mass
sim('penddemo',time); %starting the simulation
The problem is that I get this error:
can not load the Simulink SimState Because The initial model, 'penddemo', was changed after the SimState was saved. Run the simulation again and resave the SimState.
I know that there are limitations in the use of Simstate:
You cannot make any structural changes to the model between the time at which you save the SimState and the time at which you restore the simulation using the SimState. For example, you cannot add or remove a block after saving the SimState without repeating the simulation and saving the new SimState.
but I do not think changing a single variable is a structural change.
Maybe someone knows another way to change some variables before the recovery of Simstate.
Thanks all
I believe that you can only change "tunable" parameters. Try turning "Inline parameters" off, see the documentation on tunable parameters for more details
Related
Initialization could be very cumbersome and easily lead to divergence. A simple strategy is to run the simulation when building a part of the whole system and use the simulation results to modify guess values.
Here is what I got in the PPT from Francesco Casella and the book from Daniel Bouskela.
I found that I could use an option in Dymola as follows, but instead of using the initialization result, I wanna use the result when reaching a steady state. So I'd like to use a python script to extract the result from the .mat result file, then modify the iteration variables automatically. But the key problem is that I don't know when I add more components in my model, the iteration variable set of existing components would change, I don't know what kind of effect would this causes.
Anyone got opinion on this issue, welcome to answer this question.
So my question is where should I find the python
You can use the end values (= steady state) of the simulation result in order to create a new initialization (Dymola Manual 1, section 2.5.12) . If the component names are the same in the sub system model and the total model, you can run the script created in the subsystem model on the larger system model as well. But you have to check if your models have initial equations that hinder an initialization from the outside (see section 4.2 in https://2012.international.conference.modelica.org/proceedings/html/pdf/ecp12076927_KruegerMehlhaseSchmitz.pdf)
It should also be possible to initialize it steady state. Instead of providing initial values for a state x and fixing it, you can provide initial equations for the derivatives such as der(x) = 0;
With that setup activate Save Initial Results and you should be good to go.
I have written a matlab program for a simulink model and taking control through it programmatically, but I am facing one problem while using set_param('testmodel11', 'SimulationCommand', 'start');.
It gives all the values at once, that is gives the entire scope and workplace values all at the same time, but I don't want this. I would like to run the program and execute at that point, seeing only rest of the values should be zero. How can I stop the simulation at that point and fetch plots and values from that point only, the rest should be zero. And ideally have this same behavior for the next break points too?
There is a way to pause the simulation at certain breakpoints (simulation points), plot the output or do whatever is desired of it, and then continue the simulation until the next breakpoint.
However, at any breakpoint, you will get output data from all the time samples till the breakpoint is reached. To isolate data from a certain timestamp, you can calculate its index based on the sample time and extract it from the workspace (output data is stored as an array)
Here is the link to my answer which will be helpful, pls go through it:
https://stackoverflow.com/a/38348315/6580313
Now, in the m-file which you will run when the simulation is paused, you can change the value of the constant block which specifies the next simulation time at which simulation needs to be paused. In the m-file, you can also write a code snippet to access the output data.
Once the simulation continues, it will be paused at the new simulation time specified in the constant block.
Let me know in case you have any queries.
It sounds like you want to use the Simulink Debugger. Check out the documentation for more details on how to use it. The main command-line interface to it is sldebug.
I'am trying to speedup my simulink project and want to use the Accelerator-Simulation mode.
The aim of my project is to control a cyclic process and is structured as followes:
matlab-script, where all parameters and a feedforward control with
parameter estimation is implemented. Also it starts simulating the
simulink model for each iteration.
simulink model, where the dynamic system and the feedforward control (basically a lookup-table) together with a feedback control
is implemented. Parameters of all blocks are set by workspace variables/structs generated by the script.
The feedforward control variable is calculated and parameter are estimated from the simulated data after every simulation pass. Then the model is simulated again. The model is not changing during the iterations, but still it is compiling at every cycle. From the first: Is this solution appropriate for using the Accelerator mode?
I tried to follow theses proposed steps to determine, why it is built at every iteration: mathworks
If i run it with the Accelerator-Mode (referring to the documentation of this function, it now compiles for simulation), I still cannot reproduce why it is compiled at every iteration.
csdet1.ContentsChecksum.Value ~= csdet2.ContentsChecksum.Value
is true, but the proposed code does not find any details.
csdet1.InterfaceChecksum.Value ~= csdet2.InterfaceChecksum.Value
is also true, the proposed code outputs that
UserDefinedTypesChecksum
is different. What does that mean and how can I resolve this?
Sidefact: When I run Simulink.BlockDiagram.getChecksum() with the Model opened in Simulink and Normal-Mode chosen, I get this error:
Continuous update specified for this chart chartname This is not
supported for RTW."
But this chart is a Matlab-Function block, not a stateflow chart?!
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.
I am trying to control a simulink from a M-file.
What I want to do in the M-file is give the simulink model some input, run the simulink model, change one input value at 0.6 seconds, continue running the simulink model with the new input.
I already know that by using set_param, I can start, pause and continue the simulink, but the problem is I don't know how to pause the simulink model at a certain time(0.6s), is it possible to get the current time from simulink model and read it in the M-file?
Another way I already know is using sim to run simulink model from 0 to 0.6s, and use SimState to save the information at 0.6s, then load these information to resume the simulation. I am trying to change the input before the simulation resumed, but it seems that the model will load the input values from the information it saved, it won't take the new input value.
I stuck in this problem for a very long time, could someone help me with this please?
Thank you very much.
You can get the current time of a running simulation with:
get_param('simulink_model_name', 'SimulationTime');
So for instance by checking this value from your M-file during simulation by using
timer(...)
you can detect when the simulation is at 0.6 seconds.
I used a combination of simulink and m-script to achieve a similar goal.
In your model, add one 'assert' block. Double click it, and uncheck 'Stop Simulation when assertion fails'. In the 'Simulation Callback when assertion fails' field, add three commands:
set_param(bdroot,'SimulationCommand','pause');
run('myscript.m'); %insert the script name
set_param(bdroot,'SimulationCommand','continue');
Now connect the inport of this block to a 'not equal to' relational operator. Connect the first inport of the relational operator to a clock (pls set the decimation for analog clock or the sample time [usually -1 for inherited] for the digital clock).
The second inport is connected to constant block with a value of 0.6
On simulating the model, the simulation will pause at 0.6 sec, execute the m-file to change the input parameter (considering that it's tunable) and then continue with the simulation.
The assertion block is called when its input signal becomes 0. At 0.6 sec, the output of the relational operator will be 0.
Let me know if it worked.
This is not currently possible from an M-file. If you want to dynamically change the input at a given time externally, it will require an S-Function. Even this solution is difficult and wrought with flakey-ness since the Mathworks does not want to support this functionality in that it defeats one of the features of another toolbox they sell. In time, I believe they will grant this privledge, but it does not exist today. Also, why not use a dynamic input block to change the input value, like a map, signal builder, etc. ?