Area between the peak of the signal

Question

Yew Jen Chong 2022-6-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1742240-area-between-the-peak-of-the-signal

评论： Star Strider 2022-6-22

采纳的回答： Star Strider

Hi,

Anyone know how to calculate for the area of torque between the peak (triangle label) of the signal?

Can anyone please help me?

Thank you.

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Star Strider 2022-6-17

How did you identify those specific peaks?

I am having problems reproducing that with findpeaks.

Yew Jen Chong 2022-6-18

在 MATLAB Online 中打开

Hi, since the time in x-axis increase constantly, therefore the time in the second row will be selected to convert into frequency as the first row is zero. The frequency will be used in the findpeaks with minimum peak distance, minimum peak prominence, and minimum peak height is included to produce the graph above.

The code below is for producing the graph

findpeaks(cm.Torque_Nm_,Fs,'MinPeakDistance',0.016,'MinPeakProminence',5,'MinPeakHeight',6);

The code below is for storing information

[pksRT_after,locsRT_after] = findpeaks(cm.Torque_Nm_,Fs,'MinPeakDistance',0.016,'MinPeakProminence',5,'MinPeakHeight',6);

I hope I answer your question

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Answer 1

Star Strider 2022-6-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1742240-area-between-the-peak-of-the-signal#answer_987970

在 MATLAB Online 中打开

I had to tweak the code slightly to get the result I needed for the ‘areav’ and ‘absareav’ calculations.

Try this —

% opts = weboptions('ContentType','text');

% W = webread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1035225/s.m', opts)

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1035230/signal.csv', 'VariableNamingRule','preserve');

t = T1.('Time [s]');

Fs = 1/t(2);

Torque = T1.('Torque [Nm]');

env = envelope(Torque, 100, 'peak');

Lv = env >= 5;

LastIdx = find(Lv,1,'last');

[pksRT_after,locsRT_after] = findpeaks(Torque,'MinPeakDistance',100,'MinPeakProminence',20,'MinPeakHeight',6);

locsRT_afterv = [locsRT_after; LastIdx];

for k = 1:numel(locsRT_afterv)-1

idxrng = locsRT_afterv(k) : locsRT_afterv(k+1);

t_midrng(k) = median(t(idxrng)); % Used In 'text' Call

areav(k) = trapz(t(idxrng),Torque(idxrng)); % Area

absareav(k) = trapz(t(idxrng),abs(Torque(idxrng))); % Absolute Area

end

% buffer(areav,10)

% buffer(absareav,10)

figure

plot(t(Lv), Torque(Lv))

grid

hold on

plot(t(locsRT_after), pksRT_after, '^r')

% plot(t, env, '-r')

hold off

text(t_midrng, pksRT_after/2, compose(' \\leftarrow Area = %.4f',areav), 'Horiz','left', 'Vert','middle', 'Rotation',90, 'FontSize',9)

The loop uses trapz to calculate the areas between the locations denoted by the red triangles. The code then plots and labels them. (It uses the envelope function to define the area of interest in the signal for the plot.)

.