lsim with nonzero initial condition
显示 更早的评论
i have a reactor with initial temprature=90 and i have a optimal temrature trajectory as a set point . i use lsim with initial condition like this :
X0 = [90 90 90 90 90 90]; [y]=lsim(A, B, C, D, u, t , X0) plot(t,y)
but the plot is start from y( in my example is temprature) =0 how can i set my initail temprature equal to 90 in t=0?
回答（3 个）
Fangjun Jiang
2012-1-3
You can't use lsim(A,B,C,D,...). You need to use
Sys=ss(A,B,C,D);
y=lsim(Sys,u,t,X0);
UPDATE: You can't arbitrarily set your initial y. Once you get it right, Y0 should be reflected by y=Cx+Du.
It looks like lsim(A,B,C,D,...) works too. I started dislike this feature, especially it was not mentioned in the document.
Sys=rss(2);
X0=[1 1];
u=rand(101,1);
t=0:0.01:1;
y=lsim(Sys,u,t,X0);
figure(1);plot(t,y);
y2=lsim(Sys.a,Sys.b,Sys.c,Sys.d,u,t,X0);
figure(2);plot(t,y2)
Mostafa M Naseri
2012-1-3
0 个投票
1 个评论
Fangjun Jiang
2012-1-3
You are right about lsim(A, B, C, D, ...). See update in my answer.
Walter Roberson
2012-1-3
0 个投票
Mostafa, where do you see documented any ability to write lsim(A, B, C, D, u, t, X0) ? The lsim documentation appears to show that the first argument to lsim must be an LTI model.
To change the plot so that it does not start at y = 0, you could (somehow) determine the figure number of the plot, findobj() the axis for it, get() the axis YLim property, replace the lower bound of the ylim with 90, and set() that as the new axis YLim property.
类别
在 帮助中心 和 File Exchange 中查找有关 Robust Control Toolbox 的更多信息
2012-1-3
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
