Curve Fitting to high order exponential function

2015 12 30
1 个回答
回答已采纳
更新时间：2016 1 5
6 次查看（30 天）

0 个投票

Hello everybody, this is my first question here.
What I was trying to do is to fit an exponential function to a data. I already tried Matlab's Curve Fitting Tool, however it only fits exponential functions up to 2nd order. My data is more complex than that unfortunately, therefore 2nd order fit doesn't give me good result. Do you know any other tools or methods that I can use in Matlab to make the exponential fitting higher than 2nd order ?
Thanks in advance
Anil

3 个评论
显示 1更早的评论 隐藏 1更早的评论

dpb
dpb 2015-12-30
You can fit any model you can write; however, I'd ask what the purpose of this fitting is? If for interpolation, you'll likely do better with a spline; if for model estimation then is there a candidate model based on first principles?
IOW, the last thing to do is to simply start throwing more terms into an equation and hoping for good result.
Seeing the data would possibly lead to better and more specific suggestions.
John D'Errico
John D'Errico 2015-12-30
I wish I could up-vote a comment. I would do so for dpb's comment were that possible.
ANIL ALAN
ANIL ALAN 2016-1-4
Hello dpb
Thanks for the comment. Let me go a little deeper into the problem. I am going to design a controller for a physical system. Before going into to design phase, I would like to create a nice model. A part of this system is a BLDC (as actuator). I would like to create motors model by its response to a step input. I am using its own driver card and I see that when I first introduce the step position change command, driver pass the command through some kind of filter to smoothen harsh change. Eventually, I would like to model this pre-filter hoping to fit output to a linear system. Its output looks alike a linear filter of high order with most of the states zero. I attached the output data to comment.

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Rakesh Chavan
Rakesh Chavan 2016-1-5

0 个投票

Hi Alan,
Have you tried using the System Identification APP in MATLAB. It the App can be used for identifying linear models given data which I think you want to achieve. Documentation for the app can be found at the following link:
http://www.mathworks.com/help/ident/gs/identify-linear-models-using-the-gui.html
There are other functions like 'iddata' and 'ssest' where given data and order we can obtain a state space model for the plant. Kindly refer to the following link:
http://www.mathworks.com/help/mpc/gs/system-identification-toolbox-models.html
Hope this helps.

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Get Started with Curve Fitting Toolbox 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by