传递函数的拟合问题.
本帖最后由 messenger 于 2010-1-22 20:29 编辑形如(5*s^5+0.3*s^3+8*s^2+9)/(20*s^8+6*s^7+......+50*s+1)多项式的拟合问题，
现在有s从1到1000时，多项式的值
要拟合形如上式的多项式
也就是由频率响应拟合传递函数
谢谢 弱问，已经有多项式了还拟合来干什么呢！？ 2# guflei
那个多项式只是个形式，现在我只有频率响应图和数据，要拟合出一个形如上式的传递函数表达式 首先确定模型结构 也就是几阶 然后用数据拟合（拟合方法很多，比如用优化方法，最小二乘）如果不确定阶数 可以用循环 判断几阶误差最小 这个是我想的 没有验证 你可以试试 用cftool曲线拟合工具，自定义拟合函数试试看 最好把y也拿上来看看。大家一起看有什么方法作比较好~ 可以先做出输入输出曲线，通过曲线或者曲线的数据点，然后用系统辨识的经典辨识方法！！ http://home.simwe.com/attachment/200911/9/268506_1257732214i0g1.jpg
这个是辐频特性曲线 http://home.simwe.com/attachment/200911/9/268506_1257732215xwVw.jpg
这个是相频特性曲线 辐频特性数据
X: Linear dB
1 -107.24
2 -101.2
3 -97.63
4 -95.08
5 -93.06
6 -91.39
7 -89.94
8 -88.66
9 -87.49
10 -86.41
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12 -84.46
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500 -20.69 相频特性数据
X: Linear Phase degrees
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495 -97.432
496 -104.478
497 -114.537
498 -126.757
499 -139.988
500 -153.02 曲线和数据我发在下面了 6# dbx12358
页:
[1]