how can I read a graph in the Matlab app? For example, I need the logarithmic decrement of a damping sine oscillation

It is about a pendulum test with additional mass.

The pendulum is swinging and I have to find the period and the logarithmic decrement from the graph. The graph is output by an encoder

[Rohit]

Hi,

Can you please share the following information: -

• What encoder is being used in the model?
• Is App Designer being used to create MATLAB App?
• Please elaborate on what you mean by “read a graph in MATLAB App”. Do you want the graph data to be imported into the workspace or do you want to display the graph inside the MATLAB App or something else?

Along with this it would be helpful if you can share a reduced model file to understand your query/issue better.

Answer 1

[Drishti]

Hi Selim,

I understand that you are facing issue in finding the period and logarithmic decrement of a damping sine oscillation.

To determine the period and logarithmic decrement of a damped sine oscillation, I have generated dummy data simulating an encoder. The parameters used include the sampling frequency, time vector, pendulum frequency, and damping factor.

Furthermore, you can refer to below given code to calculate angle, peaks and logarithmic decrement of wave.

% Generate damped oscillation 
% t = time vector, f = frequency of pendulum, time = t 
% Generate damped oscillation 
angle = exp(-damping * t) .* cos(2 * pi * f * t); 
% Find peaks 
[peaks, locs] = findpeaks(angle, time, 'MinPeakProminence', 0.05); % Adjust 'MinPeakProminence' as needed 
% Calculate the period 
periods = diff(locs); 
average_period = mean(periods); 
% Calculate logarithmic decrement 
log_decrements = log(peaks(1:end-1) ./ peaks(2:end)); 
average_log_decrement = mean(log_decrements); (angle, time, 'MinPeakProminence', 0.05); 

For more information, you can refer to the MATLAB Documentation of ‘findpeaks’ function

https://www.mathworks.com/help/signal/ref/findpeaks.html

I hope it helps.