PID controller in Matlab script

Hi

I am having trouble figuring out how to use a pid controller within a matlab script.

I have a script that communicates with hardware that can read a sensor value and can control the output of an acutator.

I would like to implement a pid controller in the script not on the hardware.

The pid fuction in matlab creates a pid object and i understand how to set the gains but how do I actually send it an input value and recieve an output value back?

Thanks

Answer 1

[Abhishek Chakram]

Hi Joe Zisa,

It is my understanding that you want to create a PID controller in MATLAB script. You can use a “pid” controller object within a script to process input values and calculate the corresponding output. Here is a sample code for the same:

% Define PID gains
Kp = 1;  % Proportional gain
Ki = 0.1;  % Integral gain
Kd = 0.01;  % Derivative gain

% Create the PID controller object
pidController = pid(Kp, Ki, Kd);

% Initialize simulation parameters
dt = 0.01;  % Time step (s)
endTime = 10;  % Simulation end time (s)
time = 0:dt:endTime;  % Time vector

% Initialize variables for simulation
output = zeros(size(time));  % Output of the PID controller
input = sin(time);  % Example input signal (replace with actual sensor reading)
previousError = 0;  % Previous error for derivative term
integral = 0;  % Integral term

% Simulation loop
for i = 1:length(time)
    % Calculate the error signal
    setpoint = 0;  % Desired setpoint (replace with actual setpoint if variable)
    error = setpoint - input(i);
    
    % Update integral term
    integral = integral + error * dt;
    
    % Calculate derivative term
    if i == 1
        derivative = 0;
    else
        derivative = (error - previousError) / dt;
    end
    
    % Compute the PID controller output
    output(i) = Kp * error + Ki * integral + Kd * derivative;
    
    % Send the output to the actuator (replace with actual actuator control code)
    % actuatorControl(output(i));
    
    % Update previous error
    previousError = error;
    
    % Wait for next time step (optional, for real-time simulation)
    pause(dt);
end

% Plot the results (optional)
plot(time, input, time, output);
legend('Input', 'PID Output');
xlabel('Time (s)');
ylabel('Value');

In this example, the input signal is a sine wave, which you can replace with the actual sensor readings from the hardware. The commented “actuatorControl” function is a placeholder for the function to send the computed PID output to the actuator.

You can refer to the following documentation to know more about the functions used:

• pid: https://www.mathworks.com/help/control/ref/pid.html

Best Regards,

Abhishek Chakram