How to plot multiple curves in the same graph window?

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Aishwarya Govekar 2020-3-15

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/510954-how-to-plot-multiple-curves-in-the-same-graph-window

评论： Star Strider ，2020-3-16

Capture.PNG

I want to plot graphs for multiple Kp values for a proportional controller. I tried using for loop to perform this. But I didn't get the output.Below, I attach the code which I have written for your reference. Please guide me on this. If you can tell me if there's any other way to do it, then that would be great.

Kindly reply asap.

Thank you.

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Aishwarya Govekar 2020-3-15

graph.jpg

clc;
clear all;
close all;
J=20.48*10e-6;
b=0.702;
kt=14.70;
kb=0.48;
R=1.6;
L=0.02*0.001;
num=kt;
den=[(J*L) ((J*R)+(L*b)) ((b*R)+(kb*kt))];
for kp=0:50:300 %plotting graph for P controller with Kp values in steps of 50
ki=0;
kd=0;
numc=[kd,kp,ki];
denc=[0 1];
numa=conv(num,numc);
dena=conv(den,denc);
[numac,denac]=cloop(numa,dena);
step(numac,denac)
hold on;
xlabel('time(sec)'), ylabel('velocity(rad/sec)')
title ('pid control');
grid;
end

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采纳的回答

Star Strider 2020-3-15

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/510954-how-to-plot-multiple-curves-in-the-same-graph-window#answer_420216

Try this:

J=20.48*10e-6;
b=0.702;
kt=14.70;
kb=0.48;
R=1.6;
L=0.02*0.001;
num=kt;
den=[(J*L) ((J*R)+(L*b)) ((b*R)+(kb*kt))];
kp=0:50:300; %plotting graph for P controller with Kp values in steps of 50
for k = 1:numel(kp)
    ki=0;
    kd=0;
    numc=[kd,kp(k),ki];
    denc=[0 1];
    numa=conv(num,numc);
    dena=conv(den,denc);
    [numac,denac]=cloop(numa,dena);
    sys = tf(numac,denac)
    [y{k},t{k}] = step(sys);
%     QL(k,:) = [min(y{k}), max(y{k})]                    % Information
end
figure
hold on
for k = 2:numel(y)
    plot(t{k}, y{k})
end
hold off
xlabel('time(sec)'), ylabel('velocity(rad/sec)')
title ('pid control');
grid

It is necessary to create a system object to use the step funciton. The first step output is uniformly zero, and that causes problems with the plot. Start with the second one instead.

Also, use feedback rather than cloop (that has been deprecated).

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Star Strider 2020-3-16

To change the axis limits use the xlim, ylim or axis functions. To set limits on axes that are already plotted, see the documentation on Axes Properties.

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