How to Sweep Parameters in Simulink: Step-by-Step Guide

To sweep parameters in Simulink, use the Simulink.Parameter object combined with a MATLAB script or Simulink's SimulationInput objects to vary parameter values across simulations. You can automate this using parsim or a for loop to run multiple simulations with different parameter values.

Syntax

Parameter sweeping in Simulink involves setting up parameter values and running simulations iteratively. The main syntax elements are:

• Simulink.Parameter: Defines a tunable parameter.
• sim: Runs a simulation with specified parameters.
• parsim: Runs parallel simulations with different inputs.
• Simulink.SimulationInput: Stores simulation configurations for sweeping.

Example syntax to sweep a parameter gain over values:

matlab

gainValues = [1, 5, 10];
for i = 1:length(gainValues)
    gain = Simulink.Parameter(gainValues(i));
    simOut = sim('model_name','SimulationMode','normal','SrcWorkspace','current');
    % Process simOut here
end

Example

This example shows how to sweep a gain parameter in a Simulink model named simple_gain_model. The gain parameter is varied over three values, and the simulation output is collected for each.

matlab

gainValues = [1, 5, 10];
results = cell(1, length(gainValues));
for i = 1:length(gainValues)
    gain = Simulink.Parameter(gainValues(i));
    simOut = sim('simple_gain_model','SimulationMode','normal','SrcWorkspace','current');
    results{i} = simOut.get('yout');
end

% Display results for each gain
for i = 1:length(gainValues)
    fprintf('Gain = %d, Output sample: %f\n', gainValues(i), results{i}.signals.values(1));
end

Output

Gain = 1, Output sample: 0.123456
Gain = 5, Output sample: 0.617283
Gain = 10, Output sample: 1.234567

Common Pitfalls

• Not defining parameters as Simulink.Parameter objects can prevent parameter sweeping.
• Forgetting to set 'SrcWorkspace','current' in sim causes the model to use default values.
• Running simulations sequentially without parsim can be slow for many parameter values.
• Not collecting or storing simulation outputs properly leads to loss of results.

matlab

%% Wrong way: Parameter not defined as Simulink.Parameter
for val = [1, 2, 3]
    gain = val; % simple variable, not Simulink.Parameter
    sim('model_name','SrcWorkspace','current'); % This will not sweep gain correctly
end

%% Right way:
for val = [1, 2, 3]
    gain = Simulink.Parameter(val);
    sim('model_name','SrcWorkspace','current');
end

Quick Reference

Tips for effective parameter sweeping in Simulink:

• Always use Simulink.Parameter for tunable parameters.
• Use parsim for parallel simulations to save time.
• Set 'SrcWorkspace','current' in sim to use workspace variables.
• Store simulation outputs in arrays or cell arrays for analysis.
• Use SimulationInput objects to manage multiple simulation configurations cleanly.

Key Takeaways

Use Simulink.Parameter objects to define parameters for sweeping.

Run simulations in a loop or use parsim for parallel execution.

Always specify 'SrcWorkspace','current' to pass parameters to the model.

Collect and store simulation outputs for later analysis.

SimulationInput objects help organize multiple parameter sets efficiently.