How to remove pulsewidth function without shifting my data?

When I try to delete the pulsewidth function, my sensor_data switches from a 3006x3 matrix to a 3000x3 matrix, this causes the code to give me an error "arrays have incompatible sizes for this operation, I want to find a way to plot the data without having to use the pulsewidth function to shift the data so it matches up, is there any other function that could do this ? This is the part of the code

% Import the data
for k=1:size(files)
 
TestSensor = readtable(files(k,1),opts);
TestInstron = readtable(files(k,2),opts_instron);

% transfer the table data to the array
sensor_data = table2array(TestSensor(2:height(TestSensor),:));
instron_data = table2array(TestInstron(2:height(TestInstron),:));

% use pulsewidth function to get the cross
% need to adjust the 'StateLevels': 0.95, 200 if we don't get the correcct numbers.
[w,initcross,finalcross] = pulsewidth(sensor_data(:,3),sensor_data(:,1),'StateLevels',[0.95*max(sensor_data(:,3)) max(sensor_data(:,3))+201],'Tolerance',45);
gap = finalcross- initcross+Valueshift;
sensor_data_shift = sensor_data(:,1)-initcross;
mask = sensor_data_shift>0;
%Pulling Force
plot(sensor_data_shift.*mask,sensor_data(:,3).*mask,'LineWidth',1.5,'Color',[0.267, 0.447, 0.769])% RGB Blue 68, 114, 196 
hold on
%Normal Force
plot(instron_data(:,1)/SampleRate+gap,instron_data(:,3),'LineWidth',1.5,'Color',[0.929, 0.490, 0.192])% RGB Orange 237, 125, 49
%Friction
% RGB Grey 165, 165, 165
    legend('Normal Force','Pulling Force','Friction*1000')
    grid on
    title(NamedGraphTitle)
    xlabel('Time (s)')
    ylabel('Force (lbs)')
    axis([12.5,TimeendX,0,7500])
hold off

Here is picture of the graph

Answer 1

[Karan Singh]

Hi Luis,

From what I understand, the code you provided includes the “pulsewidth” function, which is used to shift the data so that it aligns correctly for plotting. However, you mentioned that removing the “pulsewidth” function causes the size of the “sensor_data” matrix to change, leading to an error when plotting the data. The error message suggests that the size mismatch between the “sensor_data” and “instron_data” arrays is causing an issue when trying to plot them together.

Instead of relying on the “pulsewidth” function, you can manually find the shift between the two datasets based on a specific criterion. Assuming if the maximum value in “sensor_data” corresponds to the start of the alignment. Here’s an example of how you can modify your code to manually align the datasets without using “pulsewidth”:

% Import the data 
for k = 1:size(files) 
    TestSensor = readtable(files(k,1), opts); 
    TestInstron = readtable(files(k,2), opts_instron); 
    
    % Transfer the table data to the array 
    sensor_data = table2array(TestSensor(2:height(TestSensor), :)); 
    instron_data = table2array(TestInstron(2:height(TestInstron), :)); 
    
    % Find the shift or alignment between the datasets 
    [~, max_index] = max(sensor_data(:, 3));  % Find the index of the maximum value in sensor_data 
    
    % Calculate the shift based on the desired criterion 
    shift = sensor_data(max_index, 1) - instron_data(1, 1); 
    
    % Plot the data with the calculated shift 
    plot(sensor_data(:, 1) - shift, sensor_data(:, 3), 'LineWidth', 1.5, 'Color', [0.267, 0.447, 0.769])  % Pulling Force 
    hold on 
    plot(instron_data(:, 1), instron_data(:, 3), 'LineWidth', 1.5, 'Color', [0.929, 0.490, 0.192])  % Normal Force 
    
    legend('Normal Force', 'Pulling Force', 'Friction*1000') 
    grid on 
    title(NamedGraphTitle) 
    xlabel('Time (s)') 
    ylabel('Force (lbs)') 
    axis([12.5, TimeendX, 0, 7500]) 
    hold off 
end 

In this modified code, we find the index of the maximum value in the “sensor_data” array and calculate the shift as the difference between the maximum value's time and the first time in the “instron_data” array. This shift is then used to align the x-axis values of the two datasets when plotting.

Attached below are some documentation links that you may find helpful:

• Maximum elements of array - MATLAB max (mathworks.com)
• Array Indexing - MATLAB & Simulink (mathworks.com) (Indexing and slicing)

Hope this helps!

Karan Singh Khati