How to calculate RMS and Crest Factor of separate data and combine into one file and one plot

Hello,

In case that I have the separate 123 mat files (bearing1_1_1.mat to bearing 1_1_123.mat) and I would like to calculate RMS and Crest Factor of each data and plot into the graph like an attached picture (RMS of data 1 to data 123), how should I write the script?

Thanks for your kind supports

Answer 1

[Sudarsanan A K]

Hi Pasu,

I understand that you are looking for a MATLAB script that would enable you to find and plot the Root Mean Square (RMS) and Crest Factor from a collection MAT files.

You can achieve this as follows:

• Load each MAT file one by one.
• Calculate the RMS and Crest Factor and store the values in arrays.
• Then, plot the RMS values and Crest Factors in separate subplots within a single figure.

Here is an example code:

%% I am creating some MAT files that store random data (for the purpose of complete demonstration) 
numFiles = 123;  % Total number of data files  
for i = 1:numFiles
    % Generate random data
    data = rand(1, 1000);  % Change the size of the data as per your requirement
    
    % Save data to mat file
    fileName = sprintf('bearing1_1_%d.mat', i);
    yourDataVariable = data;  % Assign the data to the variable name
    save(fileName, 'yourDataVariable');
end
%% Here is the structure of MATLAB script you are looking for 
% Initialize variables
numFiles = 123;  % Total number of data files
rmsValues = zeros(1, numFiles);
crestFactors = zeros(1, numFiles);

% Loop through each data file
for i = 1:numFiles
    % Load the data file
    fileName = sprintf('bearing1_1_%d.mat', i);
    data = load(fileName);
    
    % Calculate RMS
    rmsValues(i) = rms(data.yourDataVariable);  % Replace 'yourDataVariable' with the actual variable name in your mat file
    
    % Calculate Crest Factor
    crestFactors(i) = max(abs(data.yourDataVariable)) / rmsValues(i);
end

% Plot RMS and Crest Factor
figure;
subplot(2, 1, 1);
plot(rmsValues);
title('RMS');
xlabel('Data File');
ylabel('RMS Value');

subplot(2, 1, 2);
plot(crestFactors);
title('Crest Factor');
xlabel('Data File');
ylabel('Crest Factor');

You can additionally refer the MathWorks documentation for better understanding of the "sprintf()" function that I have used in the example:

https://mathworks.com/help/matlab/ref/sprintf.html

I hope this helps you resolve the issue.