I simulated the following function on matlab. now trying to simulate it on simulink. in the uploaded image the simulink block structure can be seen where i assumed a constant for (Tb),but i should implement it as a function shown in the matlab text.

function dudt = first_order2(u,kd,cd,ct,Tt,Jt,Jb,WOB,Ls,Lk,Ld,Lstr)

% u(1) = ot; u(2) = wt; u(3) = ob; u(4) = wb

%R = 0.0492;
%dc = 3.7186;

Tst = cd * (u(2) - u(4)) + kd *(u(1) - u(3));
Tcf = (2/3) * Ls * WOB;

%if u(4) * Ld <= 0.3
%    fun = @(r) 2 * WOB / R^2 * (r.^2. * ((Lk/R) + ((Ls/R) - (Lk/R))*exp(-dc*u(4)*r)));
%    Tdr = integral(fun,0,R);
%else
Tdr = ((2/3) * Lk * WOB) + (2 * WOB * (Ls - Lk) / (Ld^3 * u(4)^3)) * (2 - exp(-Ld*u(4)) * (Ld^2 * u(4)^2 + 2 * Ld * u(4) + 2)) + (0.5 * WOB * Lstr * u(4));
%end

if abs(u(4)) <= 0.001 && Tst < Tcf
    Tb = sign(u(4))*Tst;
elseif abs(u(4)) <= 0.001 && Tst >= Tcf
    Tb = sign(u(4))*Tcf;
elseif abs(u(4)) > 0.001
    Tb = sign(u(4))*Tdr;
end

dudt = zeros(4,1);

dudt(1) = u(2);
dudt(2) =(-(cd + ct) * u(2) + cd * u(4) - kd * u(1) + kd * u(3) + Tt) / Jt; 
dudt(3) = u(4);
dudt(4) = (cd * u(2) - cd * u(4) + kd * u(1) - kd * u(3) - Tb) / Jb; 

end

Answer 1

[Aquatris]

You have a couple options for implementing the Tb variable. One possibility is to use Switch Block to mimic the if conditions. Another one is to use Matlab Function Block and type your if statements inside to change Tb values.