Digital_ControlSim/sim_controlDigital.m at main · CrissCCL/Digital_ControlSim · GitHub

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clear all; close all; clc

%% Discretization of First-Order Identified Model (Non-Parametric)
Ts = 0.1;
gp  = tf(20,[50 1]);           % First-order plant
gpd = c2d(gp,Ts,'zoh');        % Discrete plant

%% PI controller parameters
Kp = 0.8; % propotional gain
Ti = 9; % integral time

%% PI controller parameters discretization
K0 = Kp + Kp*Ts/(2*Ti);
K1 = -Kp + Kp*Ts/(2*Ti);

%% Closed-Loop Simulation (Direct difference equation)
[num,den] = tfdata(gpd,'v');
t   = 0:Ts:60;
Ref = ones(1,length(t));

% Histories
y1 = 0;
u1 = 0;
error = 0;
error1 = 0;

for k = 1:length(t)
    % ---- PLANT ----
    y(k) = num(2)*u1 - den(2)*y1;

    % ---- FEEDBACK ----
    error  = Ref(k) - y(k);
    u  = u1 + K0*error + K1*error1;

    % ---- SATURATION ----
    if u > 100
        u = 100;
    end
    if u < 0
        u = 0;
    end

    % ---- UPDATE STATES ----
    y1 = y(k);
    u1 = u;
    error1 = error;

    Usim(k) = u;
end

%% PLOTS
subplot(2,1,1)
plot(t,y,'+',t,Ref,'--','MarkerSize',4)
xlabel('Time [s]'), ylabel('Response')
legend('Simulation','Reference')

subplot(2,1,2)
plot(t,Usim,'+','MarkerSize',4)
xlabel('Time [s]'), ylabel('Control signal')