Simulink: Understanding Time Steps and Sampling Frequencies

In summary: To add an input variable that is not a constant, you first need to create a new block in the workspace. In the block's properties, set the Type to "Input Variable" and the Name to the variable you want to use.
  • #1
swraman
167
0
Hi,

I have a project due that has to be done in Simulink.

I am somewhat familiar with Simulink, but some things don't make sense to me.

First off, What determines the time step between each iteration? eg. when you have a clock in the model, what determines the change in time from one iteration to the next?

I remember working with a model once, and changing something in the model changed the sampling frequency for some reason, shich makes no sense to me.

Thanks

Raman
 
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  • #2
You can change the step size in the settings of the menu bar along with what kind of numeric solver it uses. i.e. ode45,ode23, etc.
 
  • #3
So if I have a input array which is to be used in the system, then I have to make sure the values in the input array are spaced the same time apart as the step size I specify in Simulink Options?
 
  • #4
How do I add an imput variable that is not a constant?

I have an array of values that I want the system to use, but I don't know how to get it to read the array one element at a time (each iteration I want it to take in one value from the array, and as it goes on it will read down the array).

Thanks
 
Last edited:
  • #5
swraman said:
So if I have a input array which is to be used in the system, then I have to make sure the values in the input array are spaced the same time apart as the step size I specify in Simulink Options?

I'm not sure, I would google that or look on the mathworks website. It may well be that simulink just interpolates points if it needs to.
 
  • #6
swraman said:
How do I add an imput variable that is not a constant?

I have an array of values that I want the system to use, but I don't know how to get it to read the array one element at a time (each iteration I want it to take in one value from the array, and as it goes on it will read down the array).

Thanks

Again, a question for the mathworks forums.
 
  • #7
thanks i was able to solve itl its just the "from workspace" block.
 

1. What is the purpose of time steps and sampling frequencies in Simulink?

Time steps and sampling frequencies are used in Simulink to determine the time resolution and frequency of data points in a simulation. They allow for precise control over the simulation time and can help capture important details in a system's behavior.

2. How do time steps and sampling frequencies affect the accuracy of a simulation in Simulink?

The accuracy of a simulation in Simulink is heavily dependent on the time steps and sampling frequencies chosen. Smaller time steps and higher sampling frequencies generally result in a more accurate simulation, as more data points are captured and analyzed. However, this also means longer simulation times and increased computational load.

3. Can I change the time steps and sampling frequencies during a simulation in Simulink?

Yes, it is possible to change the time steps and sampling frequencies during a simulation in Simulink. This can be done by using the "Variable Step" solver option, which allows for adaptive time steps and sampling frequencies based on the system's dynamics. However, this may affect the accuracy of the simulation.

4. How do I determine the appropriate time steps and sampling frequencies for my Simulink simulation?

The appropriate time steps and sampling frequencies for a Simulink simulation depend on the dynamics of the system and the level of accuracy needed. It is recommended to start with larger time steps and lower sampling frequencies and gradually decrease them until the desired level of accuracy is achieved without significantly increasing the simulation time.

5. What happens if I choose a time step or sampling frequency that is too small or too large in Simulink?

If a time step or sampling frequency is too small, the simulation time will increase significantly, and the computational load will also increase. On the other hand, if a time step or sampling frequency is too large, important details in the system's behavior may be missed, resulting in a less accurate simulation. It is important to find a balance between these factors for an optimal simulation.

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