Solving ODE with Matlab
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%Parameters
m_d=5.0; R=0.5;I_d=m_d*(R^2)/2;
m=2.5;
f_n=1;k=m*(2*pi*f_n)^2;
a = 0.4;
%Initial Conditions
y(1)=0;theta(1)=0;
v_y(1) = 0;tau_0=8;
w(1)=0;
dt=.00001; t_final=10;
t=0:dt:t_final;
for i=1:length(t)
%First order equations
dy(i)=v_y(i);
dtheta(i)=w(i);
dw(i)=(-m*a*y(i)*(w(i))^2-2*m*y(i)*w(i)*v_y(i)+k*a*y(i)+tau_0)/(I_d+m*(y(i))^2);
dv_y(i)=-a*w(i)+y(i)*(w(i))^2-(k/m)*y(i);
%Integrating the equations using Euler integration
y(i+1)= y(i)+dy(i)*dt;
theta(i+1)=theta(i)+dtheta(i)*dt;
w(i+1)=w(i)+dw(i)*dt;
v_y(i+1)=v_y(i)+dv_y(i)*dt;
end
figure(1);
plot(t,w(1:length(t)),'k');grid on
xlabel('Time, s');ylabel('Angular velocity, rad/s');
figure(2);
plot(t,y(1:length(t)),'k');grid on
xlabel('Times,s');ylabel('Position of mass,m');
Here is my code. The problem is tau is function of time if t<=0.5s tau=tau_0 else tau=0. How can I write that in this loop?.
1 个评论
Jan
2019-4-26
Today I've formatted your code. Please use the buttons over the edit section to do this by your own in future questions.
采纳的回答
t = 0:dt:t_final;
for i = 1:length(t)
% if t<=0.5s tau=tau_0 else tau=0
if t(i) <= 0.5
tau = tau_0;
else
tau = 0;
end
...
end
The conversion from English to Matlab is easy in this case.
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