ode function 45 how to implement it

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Zlatan 2024-1-25

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https://ww2.mathworks.cn/matlabcentral/answers/2074166-ode-function-45-how-to-implement-it

评论： Star Strider 2024-1-26

all_units.xlsx

My code is not working properly, what should i change so i ge the results. I m haveing trouble with ode function and i think with these passing parameters and initial conditions.

clc
maks = xlsread("all_units.xlsx");
a=1.024;
b=1.602;
m=1574.02;
v=maks(:,24);
r=maks(:,20);
u=maks(:,23);
t1=maks(:,25);
cr=-25488;
cf=-184780;
I=1790; 
del=(maks(:,18)+maks(:,19))/2;
alfaf= atan((v+r.*a)./u)-del;
alfar= atan((v-r.*b)./u);
Fyf=alfaf*cf;
Fyr=alfar*cr;
% Time span for the simulation
tspan = [min(t1),max(t1)];
% Initial condition
x0 = [0; 0] %for v0 and r0
x0 = 2×1
     0
     0
% Solve the differential equation using ode45
[t, x] = ode45(@(t, x) myVehicleODE(t, x, delta_function(t)), tspan, initial_conditions);
Unrecognized function or variable 'initial_conditions'.
figure;
subplot(2, 1, 1);
plot(t, x(:, 1), 'b', 'LineWidth', 2);
title('Longitudinal Velocity (v)');
subplot(2, 1, 2);
plot(t, x(:, 2), 'r', 'LineWidth', 2);
title('Yaw Rate (r)');
xlabel('Time');
% State-space model of your Vehicle
function dxdt = myVehicleODE(t, x, del)
% Elements in matrices (that depend on the parameters)
a11  = (-cf-cr)/(m*u);
a12  = (((-cf*a)+(cr*b))/(m*u))-u;
a21  = ((-cf*a)+(cr*b))/(I*u);
a22  = ((-cf*a*a)-(cr*b*b))/(I*u);
b1   = cf/m;
b2   = (cf*a)/I;
% matrices
A    = [a11, a12;   % state matrix
    a21, a22];
B    = [b1;         % input matrix
    b2];
% matrix differential equation (x is the state vector for [v; r])
dxdt = A*x + B*del;
end

6 个评论
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Walter Roberson 2024-1-26

In particular see http://www.mathworks.com/help/matlab/math/parameterizing-functions.html for information on how to make cr and cf available to the function.

Star Strider 2024-1-26

Some of these problems were subsequently corrected.

It turns out to be a stiff system, and the zeros for initial conditions is another problem. (My approach to a solution as well as Comment by Sam Chak are in help wtih plotting ode function.)

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