How count pulse with matlab?

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Jamal 2016-4-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/277721-how-count-pulse-with-matlab

评论： Image Analyst 2020-5-31

pulse.zip

I have the signal outputs from the rotary encoder. I'd like to count pulses using Matlab software. How can I count pulses? I attach the signal outputs. Would you please find the attachment files. Any codes? Any Solutions?

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Jamal 2016-4-7

The sampling interval is 3.90625E-05 seconds.

Walter Roberson 2016-4-7

Is your question http://www.mathworks.com/matlabcentral/answers/266200-counting-pulses-of-rotary-encoder complete?

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Answer 1

Image Analyst 2016-4-7

3
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/277721-how-count-pulse-with-matlab#answer_216891

在 MATLAB Online 中打开

Find the bottom envelope by using imerode() (in the Image Processing Toolbox). Then subtract the envelope from the signal. Then threshold and call bwlabel to count the pulses. Or you can use diff but it's more complicated.

bottomEnvelope = imerode(signal, true(1, windowWidth));
flattenedSignal = signal - bottomEnvelope;
hold on;
plot(flattenedSignal, 'r-');
binarySignal = flattenedSignal > 50;
plot(binarySignal, 'r-');
[~, numberOfPulses] = bwlabel(binarySignal);

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Image Analyst 2016-4-7

编辑：Image Analyst 2020-5-25

在 MATLAB Online 中打开

The erosion direction needed to be changed, and the range is different than your first signal so the threshold needed to be changed. And then the bottom was a bit rough so I smoothed it with a Savitzky-Golay filter. See attached code. Here it is on just a few pulses:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
s = load('pulse.mat')
% Let's just extract a few of the pulses, not all of them since there are so many we can't see them all in the plot.
signal = s.pulse_data(1:100);
whos signal
plot(signal, 'b-', 'LineWidth', 2);
% Get the bottom envelope:
windowWidth = 19;
bottomEnvelope = imerode(signal, true(windowWidth, 1));
% It's a bit rough.  It's supposed to be a sine wave so let's fit it to a cubic
% by using a Savitzky-Golay filter
bottomEnvelope = sgolayfilt(bottomEnvelope, 3, windowWidth);
hold on;
plot(bottomEnvelope, 'r-', 'LineWidth', 2);
grid on;
flattenedSignal = signal - bottomEnvelope;
hold on;
plot(flattenedSignal, 'm-', 'LineWidth', 2);
binarySignal = flattenedSignal > 7;
plot(binarySignal, 'g-', 'LineWidth', 2);
[~, numberOfPulses] = bwlabel(binarySignal);
legend('Original', 'Bottom', 'Flattened', 'Binary');
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
% Get rid of tool bar and pulldown menus that are along top of figure.
set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Line segmentation', 'NumberTitle', 'Off')
message = sprintf('The number of pulses is %d', numberOfPulses);
uiwait(helpdlg(message));

Walter Roberson 2020-4-28

编辑：Image Analyst 2020-5-25

在 MATLAB Online 中打开

The code was doing some baseline flattening. When you do that with your signal, the little wiggles near the beginning of your pulses turn into something that were individually getting counted as pulses. So this version estimates the baseline but does not flatten the signal.

s = load('req3.mat');
% Let's just extract a few of the pulses, not all of them since there are so many we can't see them all in the plot.
signal = s.y1;
whos signal
plot(signal, 'b-', 'LineWidth', 2);
% Get the bottom envelope:
windowWidth = 19;
bottomEnvelope = imerode(signal, true(windowWidth, 1));
% It's a bit rough.  It's supposed to be a sine wave so let's fit it to a cubic
% by using a Savitzky-Golay filter
bottomEnvelope = sgolayfilt(bottomEnvelope, 3, windowWidth);
hold on;
plot(bottomEnvelope, 'r-', 'LineWidth', 2);
grid on;
flattenedSignal = signal - min(bottomEnvelope);
hold on;
plot(flattenedSignal, 'm-', 'LineWidth', 2);
binarySignal = flattenedSignal > 2;
plot(binarySignal, 'g-', 'LineWidth', 2);
[~, numberOfPulses] = bwlabel(binarySignal);
hold off
legend('Original', 'Bottom', 'Flattened', 'Binary');
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
% Get rid of tool bar and pulldown menus that are along top of figure.
%set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Line segmentation', 'NumberTitle', 'Off')
message = sprintf('The number of pulses is %d', numberOfPulses);
uiwait(helpdlg(message));

Image Analyst 2020-5-28

在 MATLAB Online 中打开

Try this:

s = load('req4.mat')
x = s.x1;
y = s.z1;
subplot(2, 1, 1);
plot(x, y, 'b-', 'LineWidth', 2);
index = findchangepts(y)
hold on;
plot(x(index), y(index), 'r*', 'LineWidth', 2, 'MarkerSize', 15);
grid on;
% This finds a point on the upward slope.  Fall down the slope until it starts to turn around again.
while y(index) > y(index - 1)
	index = index - 1;
end
xline(x(index), 'Color', 'r', 'LineWidth', 2);
caption = sprintf('Original Signal with %d elements.  Start crop at index = %d, x = %f', length(x), index, x(index));
fontSize = 20;
title(caption, 'FontSize', fontSize);
xlabel('x1', 'FontSize', fontSize);
ylabel('z1', 'FontSize', fontSize);
% Extract just the part to the right of the index (red line).
x2 = x(index : end);
y2 = y(index : end);
subplot(2, 1, 2);
plot(x2, y2, 'b-', 'LineWidth', 2);
grid on;
xlim([min(x2), max(x2)]);
xlabel('x1', 'FontSize', fontSize);
ylabel('z1', 'FontSize', fontSize);
g = gcf;
g.WindowState = 'maximized';
caption = sprintf('Cropped Signal with %d elements.', length(x2));
title(caption, 'FontSize', fontSize);

SHANTANU KSHIRSAGAR 2020-5-31

the findchangepts is not working due to absence of signal processing toolox. Is there any way similarly robust.

Image Analyst 2020-5-31

在 MATLAB Online 中打开

Find the first place where the signal exceeds 2.5 and then fall down the left side until it turns around.

% Initialization steps.  Brute force cleanup of everything currently existing to start with a clean slate.
clc;    % Clear the command window.
fprintf('Beginning to run %s.m ...\n', mfilename);
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
s = load('req4.mat')
x = s.x1;
y = s.z1;
subplot(2, 1, 1);
plot(x, y, 'b-', 'LineWidth', 2);
index = find(y > 2.5, 1, 'first');
hold on;
plot(x(index), y(index), 'r*', 'LineWidth', 2, 'MarkerSize', 15);
grid on;
% This finds a point on the upward slope.  Fall down the slope until it starts to turn around again.
while y(index) > y(index - 1) && index >= 2
	index = index - 1;
end
xline(x(index), 'Color', 'r', 'LineWidth', 2);
caption = sprintf('Original Signal with %d elements.  Start crop at index = %d, x = %f', length(x), index, x(index));
fontSize = 20;
title(caption, 'FontSize', fontSize);
xlabel('x1', 'FontSize', fontSize);
ylabel('z1', 'FontSize', fontSize);
% Extract just the part to the right of the index (red line).
x2 = x(index : end);
y2 = y(index : end);
subplot(2, 1, 2);
plot(x2, y2, 'b-', 'LineWidth', 2);
grid on;
xlim([min(x2), max(x2)]);
xlabel('x1', 'FontSize', fontSize);
ylabel('z1', 'FontSize', fontSize);
g = gcf;
g.WindowState = 'maximized';
caption = sprintf('Cropped Signal with %d elements.', length(x2));
title(caption, 'FontSize', fontSize);