Plot now showing correctly
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I was working on my code like 10 days ago in 2025a, the code is running and the plot is showing correctly. I decided to run again to take some screenshot of my plot but my plot is no longer displaying correctly. If I print the plot, I will see the correct plot on the print dialog but the original plot window is showing up very bad. Screenshot applied. Please any immediate help will be appreciated as this is my school assignment.
My computer is Linux Ubuntu 22.04
clear all; close all; clc;
%% System Parameters
% Physical parameters of the DC motor
Ra = 1.0; % Armature resistance (Ohm)
La = 0.5; % Armature inductance (H)
J = 0.01; % Moment of inertia (Nms^2/rad)
b = 0.1; % Damping coefficient (Nms)
KT = 0.01; % Torque constant (Nm/A)
Ke = 0.01; % Back EMF constant (Nm/A)
K = Ke; % In SI units, Ke = Ki = K
%% Transfer Function Definition
% Open loop transfer function: θ(s)/Ea(s)
% G(s) = K / [(Js + b)(Las + Ra) + K^2]
% Coefficients calculation
num = K;
den_coeff = [J*La, (J*Ra + b*La), (b*Ra + K^2)];
den = den_coeff;
% Create transfer function
G = tf(num, den);
% Display the transfer function
fprintf('Open Loop Transfer Function:\n');
fprintf('G(s) = %.4f / (%.4fs^2 + %.4fs + %.4f)\n', num, den(1), den(2), den(3));
%% Performance Specifications
% Desired specifications:
% - Settling time (Ts) < 2 seconds
% - Percentage Overshoot (PO) < 5%
% - Steady State Error (SSE) < 1%
fprintf('\nDesired Specifications:\n');
fprintf('- Settling time (Ts) < 2 seconds\n');
fprintf('- Percentage Overshoot (PO) < 5%%\n');
fprintf('- Steady State Error (SSE) < 1%%\n\n');
%% Step 1: Open Loop Response
fprintf('=== STEP 1: OPEN LOOP RESPONSE ===\n');
figure(1);
[y1, t1] = step(G);
plot(t1, y1, 'b-', 'LineWidth', 2);
title('Open Loop Step Response');
xlabel('Time (seconds)');
ylabel('Angular Position (rad)');
grid on;
% Calculate performance metrics for open loop
stepinfo_ol = stepinfo(G);
fprintf('Open Loop Performance:\n');
fprintf('Rise Time (Tr): %.4f seconds\n', stepinfo_ol.RiseTime);
fprintf('Settling Time (Ts): %.4f seconds\n', stepinfo_ol.SettlingTime);
fprintf('Peak Overshoot: %.2f%%\n', stepinfo_ol.Overshoot);
% Steady state error calculation (for unit step)
% For Type 0 system: ess = 1/(1+Kp) where Kp = lim s->0 G(s)
Kp_ol = dcgain(G);
ess_ol = 1/(1+Kp_ol) * 100; % Convert to percentage
fprintf('Steady State Error: %.2f%%\n', ess_ol);
fprintf('Comments: Open loop system is unstable or has poor performance\n\n');
Bad Plot
Print Dialog
7 Comments
Your code works correctly here and in MATLAB Online --
clear all; close all; clc;
%% System Parameters
% Physical parameters of the DC motor
Ra = 1.0; % Armature resistance (Ohm)
La = 0.5; % Armature inductance (H)
J = 0.01; % Moment of inertia (Nms^2/rad)
b = 0.1; % Damping coefficient (Nms)
KT = 0.01; % Torque constant (Nm/A)
Ke = 0.01; % Back EMF constant (Nm/A)
K = Ke; % In SI units, Ke = Ki = K
%% Transfer Function Definition
% Open loop transfer function: θ(s)/Ea(s)
% G(s) = K / [(Js + b)(Las + Ra) + K^2]
% Coefficients calculation
num = K;
den_coeff = [J*La, (J*Ra + b*La), (b*Ra + K^2)];
den = den_coeff;
% Create transfer function
G = tf(num, den);
% Display the transfer function
fprintf('Open Loop Transfer Function:\n');
fprintf('G(s) = %.4f / (%.4fs^2 + %.4fs + %.4f)\n', num, den(1), den(2), den(3));
%% Performance Specifications
% Desired specifications:
% - Settling time (Ts) < 2 seconds
% - Percentage Overshoot (PO) < 5%
% - Steady State Error (SSE) < 1%
fprintf('\nDesired Specifications:\n');
fprintf('- Settling time (Ts) < 2 seconds\n');
fprintf('- Percentage Overshoot (PO) < 5%%\n');
fprintf('- Steady State Error (SSE) < 1%%\n\n');
%% Step 1: Open Loop Response
fprintf('=== STEP 1: OPEN LOOP RESPONSE ===\n');
figure(1);
[y1, t1] = step(G);
plot(t1, y1, 'b-', 'LineWidth', 2);
title('Open Loop Step Response');
xlabel('Time (seconds)');
ylabel('Angular Position (rad)');
grid on;
% Calculate performance metrics for open loop
stepinfo_ol = stepinfo(G);
fprintf('Open Loop Performance:\n');
fprintf('Rise Time (Tr): %.4f seconds\n', stepinfo_ol.RiseTime);
fprintf('Settling Time (Ts): %.4f seconds\n', stepinfo_ol.SettlingTime);
fprintf('Peak Overshoot: %.2f%%\n', stepinfo_ol.Overshoot);
% Steady state error calculation (for unit step)
% For Type 0 system: ess = 1/(1+Kp) where Kp = lim s->0 G(s)
Kp_ol = dcgain(G);
ess_ol = 1/(1+Kp_ol) * 100; % Convert to percentage
fprintf('Steady State Error: %.2f%%\n', ess_ol);
fprintf('Comments: Open loop system is unstable or has poor performance\n\n');
.
Samuel
on 14 Jul 2025
Moved: Steven Lord
on 14 Jul 2025
If I remember correctly, The MathWorks uses Ubuntu here and in MATLAB Online.
ver
.
Samuel
on 14 Jul 2025
Star Strider
on 14 Jul 2025
I ran it again in MATLAB Online just now three times in succession, and it continues to plot correctly every time.
Omar
on 24 Oct 2025
Moved: Dyuman Joshi
on 24 Oct 2025
Did you solved it, I have the same problem with Matlab R2025b
@Omar, Can you enter "computer" at the Command Window or provide the info about your computer on which MATLAB is running?
computer
Answers (1)
IBE PETER
on 29 Oct 2025
Moved: Walter Roberson
on 29 Oct 2025
0 votes
I was able to solve it by using a different linewidth in the plot command. plot(t1, y1, 'b-', 'LineWidth', 2); Change that 2 to like 0.5
1 Comment
DGM
on 30 Oct 2025
This appears to be a known bug:
I can't find anything in the bug reports though.
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on 30 Oct 2025
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