I need help for optimization using Ga (2024)

What do you mean by "to minimize the error between force and displacement"? The reason I ask is that force and displacement do not have the same physical unit dimension. Although it is possible to compute the error between two variables of different units, does the optimal result retain interpretable meaning in the sense of human reasoning?

I mean to minimize the error between the chart that obtained from ansys and the desired chart

Note : chart between force and displacement

Hi @noura, Could you please provide a sketch of the "charting error" and evaluate how you plan to make effective use of the code snippet in the Answer below? Your feedback is essential for implementing the given code correctly.

I need to make optimization using ga to minimize the error between simulated and desired chart as mentioned. The parameters ( height , depth , width ) of a cuboid

Since you already have the code to run the sim, getting the "Simulated Displacement" points and the "Desired Displacement" points into the "data" array in @Walter Roberson's code should be a relatively easy thing to do.

Since the cuboid's dimension cannot be zero or infinity, estimate some realistic values for the lower and upper bounds for the GA to search within these bounded regions.

data = Something Appropriate to set up data

numvar = 3;

A = []; b = [];

Aeq = []; beq = [];

lb = [0, 0, 0];

ub = [inf, inf, inf];

best = ga(@(x)Simulate_force(x, data), numvar, A, b, Aeq, beq, lb, ub);

function val = Simulate_force(x, data)

force = something appropriate using data

displacement = something else appropriate using data

val = sum((force - displacement).^2);

end

figure

imshow(imread('Messenger_crea...ef71aba6.jpeg'))

x = [1 2.5 10:10:100];

simulated = 0.007 * x;

desired = 0.021 * x;

objfcn = @(b,x) b(1) + b(2).*x; % Objective Function

ftns = @(b) norm(desired - objfcn(b,simulated)); % Fitness Function

% PopSz = 500;

% Parms = 2;

% optsAns = optimoptions('ga', 'PopulationSize',PopSz, 'InitialPopulationMatrix',randi(1E+4,PopSz,Parms)*1E-3, 'MaxGenerations',5E3, 'FunctionTolerance',1E-10); % Options Structure For 'Answers' Problems

% t0 = clock;

% fprintf('\nStart Time: %4d-%02d-%02d %02d:%02d:%07.4f\n', t0)

% [B,fval,exitflag,output,population,scores] = ga(ftns, Parms, [],[],[],[],zeros(Parms,1),Inf(Parms,1),[],[],optsAns);

% t1 = clock;

% fprintf('\nStop Time: %4d-%02d-%02d %02d:%02d:%07.4f\n', t1)

% GA_Time = etime(t1,t0)

% DT_GA_Time = datetime([0 0 0 0 0 GA_Time], 'Format','HH:mm:ss.SSS');

% fprintf('\nElapsed Time: %23.15E\t\t%s\n\n', GA_Time, DT_GA_Time)

%

% fprintf('Fitness value at convergence = %.4f\nGenerations \t\t\t\t = %d\n\n',fval,output.generations)

%

% fprintf(1,'\tRate Constants:\n')

% for k1 = 1:length(B)

% fprintf(1, '\t\tB(%2d) = %8.5f\n', k1, theta(k1))

% end

B = ga(ftns, 2)

figure

plot(x, simulated, 'o-', 'DisplayName','Simulated Displacement')

hold on

plot(x, desired, 'x-', 'DisplayName','Desired Displacement')

plot(x, objfcn(B, simulated), 'sr-', 'DisplayName','Optimised Result')

hold off

grid

legend('Location','best')

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  https://jmaab.mathworks.com/matlabcentral/answers/2146194-i-need-help-for-optimization-using-ga#comment_3240769

• Link

  Direct link to this comment

  https://jmaab.mathworks.com/matlabcentral/answers/2146194-i-need-help-for-optimization-using-ga#comment_3240779