Why " The boundary condition function BCFUN should return a column vector of length 5" error message is came?
10 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
% function Y6
solinit = bvpinit(linspace(0,1),[0;3;1;1],2);
sol = bvp4c(@ode, @bc, solinit);
y = sol.y;
time = sol.parameters*sol.x;
ut = -y(4,:);
figure(1);
plot(time,y([1 2],:)','-'); hold on;
plot(time, ut, 'k:');
axis([0 time(1,end) -1.5 3]);
text(1.3,2.5,'x_1(t)');
text(1.3,.9,'x_2(t)');
text(1.3,-.5,'u(t)');
xlabel('time');
ylabel('states');
title('Numerical solution');
hold off;
% -------------------------------------------------------------------------
% ODE's of augmented states
function dydt = ode(t,y,T)
dydt = T*[2*y(2);4*y(4);0;-2*y(3)];
end
% -------------------------------------------------------------------------
% boundary conditions: x1(0)=11;p2(0)=2; x2(tf)=3; 3*p1(tf)+p2(2)^2=0
function res = bc(ya,yb,T)
res = [ ya(1) - 11; ya(4); yb(2) - 3; 3*yb(3)+yb(4)^2];
end
0 Kommentare
Akzeptierte Antwort
Jan
am 14 Nov. 2022
You provide an extra parameter:
solinit = bvpinit(linspace(0,1),[0;3;1;1],2);
% ^ here
But there is no condition for this parameter in bc().
4 Kommentare
Jan
am 16 Nov. 2022
This not trivial. If you do not know, which function u is, there is an infinite number of possible solutions. This is an optimization problem and not a simple BVP.
Weitere Antworten (1)
Torsten
am 16 Nov. 2022
Bearbeitet: Torsten
am 16 Nov. 2022
Choose a grid
0=t0 < t1 < ... < tn = tf
With each grid point, associate a value ui of your control function u (the ui are your solution variables for the optimization problem).
Call fmincon with initial values for the ui.
Within the objective function for fmincon, solve the boundary value problem from above with the given vector u (e.g. using bvp4c or your own ODE solver for this simple boundary value problem) and return the value for J to the optimizer. The integral can be approximated by the trapezoidal rule, e.g.
Maybe the YouTube video is of help:
3 Kommentare
Torsten
am 16 Nov. 2022
I described the steps you have to follow and even gave a link to a video where everything is described in detail. This is all I can do for you - the task is not a "one-liner".
Siehe auch
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!