Does simulation time affect on the results of the simulation ?
if the simulation time is long , the results are more accurate of the results when the simulation time is short .
6000s simulation time isn't as 3600s or 1800s simulation time .
Related
I want to stop the model at a specific model time.
Do I have to work with a counter variable per time and then throw stopSimulation() or is there another possibility? My simulation will run for one week in model time. I want to stop the simulation 5min before it will end, so 5min before one week of model time is over.
You can specify the stop time in the simulation experiment properties. See below:
In the settings of Simulation:main you can define exactly when you want your simulation to stop.
See attached image:
To set a week less 5 minutes, replace the number 100 with the number 10,075 (assuming your model runs in units of minutes)
Good luck
i am new to carla and have one question regarding the statement (below mentioned) in carla docu:
how to understand the simulation time and time step mentioned in the statement? Is this same as rendering frame?
"There is a difference between real time, and simulation time. The simulated world has its own clock and time, conducted by the server. Computing two simulation steps takes some real time. However, there is also the time span that went by between those two simulation moments, the time-step."
Thank you for your help!
So you might set a simulation time of 5 seconds to model something - like how far the ripples progress in water when a stone hits the surface.
But the computer/processor may take 5 minutes to complete all the calculations to provide that solution.
In Dymola, I'm able to do something like:
when time > 100 then
assert(false,"Simulation taking too long");
end when;
to stop simulations based on the time variable itself.
However, what i'd like to do is stop the simulation based on elapsed CPU time. Dymola has a way to output the CPU time and it shows up in the results as CPUtime, but I don't know how to access the variable. In other words, this is what i'd like to do, but the CPUtime variable isn't in scope:
when CPUtime > 100 then
assert(false,"Simulation taking too long");
end when;
Any suggestions, either how to access CPUtime, or other workarounds to kill simulations based on cpu time?
As already noted:
You can set this in Dymola 2022 in the simulation setup, or alternatively by setting Advanced.Simulation.MaxRunTime.
It's wall-clock time, which means that if you have a parallel simulation it will stop after 10s has passed and not when the cores together have spent 10s, and if you for some weird reason have a long sleep-call in the model it will still end.
(This was already noted in the comment - thanks Priyanka. However, stackoverflow for some reason warns that answers in comments may be lost.)
I have made some measurements with an NI6024 acquisition card using Simulink, with the following model:
I have run the simulation with simulation time = "inf" and a fixed time step of 0.2, in order to collect real time data from the card. But I didn't realize that the values that "Clock" gives do not correspond to real-world time. More specifically, I have run the experiment for about a minute but the data in the variable "t" range from 0 to about 50000, which is clearly wrong. I have saved the workspace data, and I have access to the recorded data (the variables "t" and "h"), but have no means to reproduce the experiment.
Is there any way to retrieve the real world time of the simulation?
You've basically got two choices.
Run your model in real time, using for instance something like Simulink Real-Time, or other real time OS. In this case the (wall clock) time will represent time since the model was started.
Write an S-Function to slow down the simulation so that it fakes real time. There are multiple examples of doing this on the File Exchange. See Real-Time Pacer for Simulink for one such example.
This is a very basic question. I can't simulate a PWM file, in system time, from its FPGA VI file.
Details
For a NI cRIO-9067 + LabVIEW 2016 + Windows 8 system, under FPGA Interface Mode, I have the Test VI No.1.vi NI LabVIEW file and the corresponding FPGA Desktop Execution Node block file Test VI No.1 DEN.vi as suggested in the Getting Started information [1] [2].
In both files, the Low Pulse and High Pulse Numeric Controls are filled with the 1000 value. The Loop Timer block is set as "mSec" Counter Unit and "32 Bit" Size of Internal Counter.
The compiled FPGA version of the first file executes a square wave changing each 1 second, as expected, after 7 minutes of local compilation.
Under Simulation (Simulated I/O) as Execution Mode, and for reproducing approximatedly and by trial and error the square wave timing every 1 second, I need to put the value 1750 in the Clock Ticks field, from the FPGA 40MHz Onboard Clock reference clock, shown in the block options.
I dont understand this block, and why i should not put any close divisor of 40,000,000 at the Clock Ticks field, or simply, the value 1. Basically i dont understand how to "time" these FPGA simulations.
The desktop execution node is designed for time based simulation you are definately on the right track.
What you are setting at the top is the number of cycles that are executed each time you call the node. In your case you have 1750 ticks so around 43.75us of simulated time per iteration.
To simulate in real time you need to make sure that you execute the same amount of simulated time as the simulation loop takes to run. In your case, you have no timing in your simulation loop so why 1750 works for you is because that is probably how long that loop takes to execute.
If you put a loop timer in of 1ms and set the clock ticks to 40,000 (1ms simulated time) then I think you will find that it also works.
In some cases it may be beneficial to execute faster than real time so you would just have to account for that in your maths. For example if you set the clock ticks to 40 (1us simulated time) then you can count the number of iterations and multiply by 1us to get the actual clock time.