i have the next error but idk wheres the problem.

Heres the error.

Error using nlmpc/nlmpcmove
Expected "Parameters" to be a vector.

Error in TESIS_JL (line 94)
[uk, info] = nlmpcmove(nlobj, xk, uk, ref);

heres my program, NMPC:

%% NMPC
 % Parámetros de la planta de temperatura

Ta = 23 + 273.15;   % K
U = 10.0;           % W/m^2-K
m = 4.0/1000.0;     % kg
Cp = 0.5 * 1000.0;  % J/kg-K    
A = 12.0 / 100.0^2; % Area in m^2
alpha = 0.01;       % W % heater
eps = 0.9;          % Emissivity
sigma = 5.67e-8;    % Stefan-Boltzman

Par = [Ta;U;m;Cp;A;alpha;eps;sigma];
  
%% Crear objeto NMPC

nx = 1; %Estados
ny = 1; %Salidas
nu = 1; %entradas
nlobj = nlmpc(nx,ny,nu);
nlobj.States.Name = 'T';
nlobj.MV.Name = 'H';


nlobj.Model.StateFcn = @(x,u,Par) prediction_model_jl(x,u,Par);
% No output function specified. Assuming "y = x" in the prediction model.
nlobj.Model.IsContinuousTime = true; 
nlobj.Model.NumberOfParameters=1;

%% Restricciones NMPC
nlobj.States.Min = 0;

nlobj.MV.Min = 0;    
nlobj.MV.Max = 100;  

nlobj.MV.RateMin = -100;   
nlobj.MV.RateMax = 100;   

%% NMPC Sintonización
N=14;
Nu=10;
delta=0.69408;
lambda=0.24209;
Ts = 8;
nlobj.Ts = Ts;                                 
nlobj.PredictionHorizon = N;                  
nlobj.ControlHorizon = Nu;                
nlobj.Weights.OutputVariables = delta;
nlobj.Weights.ManipulatedVariablesRate = lambda;
%% Validacion de las funciones;
T = 23 + 273.15;
x0 = T;
Q = 0;
u0 = (Q);
validateFcns(nlobj,x0,u0,[],{Par});

Model.StateFcn is OK.
No output function specified. Assuming "y = x" in the prediction model.
Analysis of user-provided model, cost, and constraint functions complete.

%% Ingreso de señales de referencia
t = linspace(0, 10, 1000); % Adjust the time range and number of samples as needed
% Define the initial value before the step
initialValue = 23+273.15;
% Define the value after the step
stepValue = 50;
% Define the step time
stepTime = 5;
% Create the step function
ref = initialValue + stepValue * (t >= stepTime);
ref = reshape(ref, [], 1);
%% Simulation settings
% Define simulation parameters
timestep = 0.1; % Time step for simulation
numSteps = 100; % Number of simulation steps

% Preallocate arrays to store results
time = linspace(0, timestep*numSteps, numSteps);
states = zeros(1, numSteps);
controls = zeros(1, numSteps);

% Initial state and control input
xk = Ta; % Initial temperature
uk = 0; % Initial control input

% Simulate the NMPC applied to the plant
for k = 1:numSteps
    % Measure the current state of the plant
    yk = xk; % Here, we assume the measured state is equal to the actual state

    % Compute the optimal control action using NMPC
    [uk, info] = nlmpcmove(nlobj, xk, uk, ref);

    % Apply the control action to the plant and simulate the dynamics
    [~, xk_next] = ode45(@(t, x) heat2(t, x, Q), [0 timestep], xk);

    % Update the current state
    xk = xk_next(end);

    % Store the state and control input for analysis
    states(k) = xk;
    controls(k) = uk;
end

Error using nlmpc/nlmpcmove
Expected "Parameters" to be a vector.

% Plot the results
figure;
plot(time, states);
xlabel('Time');
ylabel('Temperature');
title('Temperature Response');

Prediction model

function dTdt = prediction_model_jl(x,u,Par)
    
    % Parameters
 Ta = Par(1);   % K
 U = Par(2);           % W/m^2-K
 m = Par(3);     % kg
 Cp = Par(4);  % J/kg-K    
 A = Par(5); % Area in m^2
 alpha = Par(6);       % W / % heater
 eps = Par(7);          % Emissivity
 sigma = Par(8);    % Stefan-Boltzman       % Stefan-Boltzman
  
    % Temperatura
    T= x(1);
    
    % Entradas
    Q= u(1);  

    % Ecuaciones de los balances de energía

   dTdt = (1.0/(m*Cp))*(U*A*(Ta-T) ...
            + eps * sigma * A * (Ta^4 - T^4) ...
            + alpha*Q);
end

Plant model

function dTdt = heat2(time,x,Q)
    % Parameters
    Ta = 23 + 273.15;   % K
    U = 10.0;           % W/m^2-K
    m = 4.0/1000.0;     % kg
    Cp = 0.5 * 1000.0;  % J/kg-K    
    A = 12.0 / 100.0^2; % Area in m^2
    alpha = 0.01;       % W / % heater
    eps = 0.9;          % Emissivity
    sigma = 5.67e-8;    % Stefan-Boltzman

    % Temperature State
    T = x(1);

    % Nonlinear Energy Balance
    dTdt = (1.0/(m*Cp))*(U*A*(Ta-T) ...
            + eps * sigma * A * (Ta^4 - T^4) ...
            + alpha*Q);
end

Answer 1

[Walter Roberson]

You might need to set nlobj.Parameters to a cell array containing the sample time.