how to assign initial values to scalar quantities in simulink function. please help

function [P_dot, Q_dot, R_dot, phi_dot, theta_dot, psi_dot] = fcn(P,Q, R,phi, theta, psi, step_force_x, step_force_y, step_force_z)

%% parameters

mass = 5;

x = 0.3; % length

y = 0.2; % width

z = 0.1; % height

rx = 0.1; ry = 0.2; rz = 0.1;

% equations

tow_x = ((ry * step_force_z) - (rz * step_force_y)); % along x-axis

tow_y = ((rz * step_force_x) - (rx * step_force_z)); % along y-axis

tow_z = ((rx * step_force_y) - (ry * step_force_x)); % along z-axis

Jx = (mass / 12) * (y^2 + z^2);

Jy = (mass / 12) * (x^2 + z^2);

Jz = (mass / 12) * (x^2 + y^2);

Jxz = 0;

omega_x = tow_x / Jx; % calculating initial values of angular velocity

omega_y = tow_y / Jy;

omega_z = tow_z / Jz;

% Angular moments

Lx = Jx * omega_x;

Ly = Jy * omega_y;

Lz = Jz * omega_z;

% Calculate gamma

gamma = (Jx * Jz) - (Jxz^2);

% OMEGA_dot

P_dot = ((Jxz*(Jx-Jy+Jz)*P*Q)/gamma) - (((Jz*(Jz-Jy)+Jxz^2)*Q*R)/gamma) + ((Jxz*Lz)/gamma) + (Jz*Lx)/gamma;

Q_dot = ((Jz - Jx)*P*R)/Jy - (Jxz*(P^2 - R^2))/ Jy + (Ly / Jy);

R_dot = ((Jx*(Jx-Jy)+Jxz^2)*(P*Q)/gamma) - (((Jxz*(Jx-Jy+Jz))*P*R)/gamma) + ((Jx*Lz)/gamma) + (Jxz*Lx)/gamma;

%EUL_dot

phi_dot = P + Q * sin(phi) * tan(theta) + R * cos(phi) * tan(theta);

theta_dot = Q * cos(phi) - (R * sin(phi));

psi_dot = Q * sin(phi) / cos(theta) + R * cos(phi) / cos(theta);

end

Answer 1

[Sam Chak]

Hi @John

You can insert the initial values in the Integrator block as shown in the example below:

[John]

thanks bravo