About comparision results mismatch in System Identification Toolbox
10 次查看(过去 30 天)
显示 更早的评论
Hi all, I'm currently using the SIT to estimate the state space model of a multiple input multiple output (MIMO) system.
I am able to get the corresponding 'A', 'B', 'C', 'D' and 'K' matrices based on my inputs and outputs, using the 'n4sid' method, and the fitting result seems to be really good (higher than 95%). I want to simulate these results in my m-files, and I use the same inputs values and the matrices from above estimation, simply as
x(k+1) = A*x(k) + B*u(k) and y(k+1) = C*x(k) (D is an empty matrix).
Here comes the problem: the simulated result 'y(k+1)' is far away from my measurement outputs values, which is also the one I used in SIT estimation. I tried once with fixing K=0, but result was still the same. There might be some influence from the noise, but I don't think it's that large.
Could someone explain me why this happen? And I am also wondering how could the SIT get the simulated output curve in the 'Model Output' option.
Thank you so much for your help!
1 个评论
Xiwang
2013-7-2
Hey, Yiming,
I am also using the N4sid toolbox. Can I ask you how to use N4sid to get the corresponding 'A', 'B', 'C', 'D' and 'K' matrices?
Thanks very much.
xiwang
回答(1 个)
Arkadiy Turevskiy
2013-4-8
Most likely the issue is due to not using the proper initial conditions as explained in the previous post.
HTH.
Arkadiy
0 个评论
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Correlation Models 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!