PID controller for m file

Hi

I have system (NOT transfer function) that gives vector numbers. Also, I have specific desire output. I would like to add PID controller as a control to reduce the error between the desire and output based on specific variable (d). Can you please help me with this situation

For example,

A=[0 3 12.5 12.8 11.8 12.3 11.9 12]; % practical data

d=1; % variable

OUT=A*d; % output

Vdesire=12; % desire output

[Mathieu NOE]

hello

does A somehow represent a step input response ?

[mohammed hussein]

thank you for your response

No it just a vector of numbers , it could be a second order response from a complex system . However , i have only numbers without transfer function

[Mathieu NOE]

I don't understand your data

systems are either given by models , FRFs , or time models (impulse or step response)

[mohammed hussein]

A is a practical data changed with time .

[Mathieu NOE]

sorry, it's still unclear for me

where does this data come from , and how it has been genrated and collected , and if it's a system output what was the corresponding input ?

Answer 1

[Umar]

Hi @ mohammed hussein,

To implement a PID controller in MATLAB for your specific scenario, we will follow these steps:

Define the System Parameters: start by defining the practical data, the variable d, and the desired output Vdesire. Calculate the Output: The output will be calculated based on the provided data and the variable d. Implement the PID Controller: set up the PID controller to minimize the error between the desired output and the actual output. Simulate the Control Process: run a simulation to observe how the PID controller adjusts the output over time. Display the Results: Finally, visualize the results to understand the performance of the PID controller. Here is the complete MATLAB code that accomplishes the above tasks:

% Step 1: Define the System Parameters
A = [0 3 12.5 12.8 11.8 12.3 11.9 12];  % Practical data
d = 1;                                    % Variable
OUT = A * d;                              % Output
Vdesire = 12;                             % Desired output

% Step 2: Initialize PID Controller Parameters
Kp = 1;   % Proportional gain
Ki = 0.1; % Integral gain
Kd = 0.5; % Derivative gain

% Step 3: Initialize Variables for PID Control
error = zeros(size(OUT));   % Error vector
integral = 0;               % Integral term
previous_error = 0;        % Previous error for derivative term
dt = 1;                     % Time step (assuming uniform time intervals)

% Step 4: Control Loop
for i = 1:length(OUT)
  % Calculate the error
  error(i) = Vdesire - OUT(i);

    % Update the integral term
    integral = integral + error(i) * dt;

    % Calculate the derivative term
    derivative = (error(i) - previous_error) / dt;

    % Calculate the PID output
    PID_output = Kp * error(i) + Ki * integral + Kd * derivative;

    % Update the output based on PID control
    OUT(i) = OUT(i) + PID_output;

    % Update previous error
    previous_error = error(i);
  end

% Step 5: Display the Results
disp('Final Output after PID Control:');
disp(OUT);

% Plotting the results for visualization
figure;
plot(1:length(A), A, 'b-o', 'DisplayName', 'Original Output');
hold on;
plot(1:length(OUT), OUT, 'r-x', 'DisplayName', 'PID Controlled Output');
yline(Vdesire, 'g--', 'Desired Output', 'DisplayName', 'Desired Output');
xlabel('Time Step');
ylabel('Output Value');
title('PID Controller Output Adjustment');
legend show;
grid on;

Please see attached.

Explanation of the Code

Initialization: The code begins by defining the practical data, the variable d, and the desired output Vdesire. PID Parameters: The proportional, integral, and derivative gains (Kp, Ki, Kd) are initialized. These parameters can be tuned based on the specific requirements of your system. Control Loop: The loop iterates through each output value, calculating the error, updating the integral and derivative terms, and adjusting the output based on the PID control law. Results Display: The final output after applying the PID controller is displayed, and a plot is generated to visualize the original output, the PID-controlled output, and the desired output.

By adjusting the PID parameters, you can fine-tune the controller's performance to achieve the desired output effectively. Feel free to modify the gains and observe how they affect the system's response.

[mohammed hussein]

Thank you so much for your answer