A transfer function out of a complex function

7 次查看（过去 30 天）
Sydney Flowers
Sydney Flowers 2013-6-5
Hi everyone, got this problem when trying to design a PID controler, so the function is here:
L=(4*exp(-t)+4*t+6)/10
i just can't get it right with all this num and den coefficients since this is a combination of ordinary function and an exponential fucntion. the question is: how do i turn it to a transfer function? got lost really.
Thanks, Sydney.
  2 个评论
Sydney Flowers
Sydney Flowers 2013-6-5
编辑：Sydney Flowers 2013-6-5
L is a function which indicates the change of the location of the rotor in time - Z-axis vibration. The function in question is a simplified law, out of which the sin(omega) was taken away and replaced by 1, for i had no idea how to make it in tf, and c and b coefficients were made numeric constants.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（2 个）

David Sanchez
David Sanchez 2013-6-5
substitute in your L function:
exp(x) = 1 + x + (x^2)/4 % Taylor expansion
Operate until you obtain your num and den, then:
my_sys = tf( num, den )
Azzi Abdelmalek
Azzi Abdelmalek 2013-6-5
If L is your impulse response, Maybe L is
%L(t)=0.1(4exp(-t)-4t+6)u(t) % u(t) is a step function
The transfer function of your system is the Laplace transform of your impulse response
%L(p)=0.1*(4*1/(p+1)-4*1/p^2+6/p)
%L(p)=0.4/(p+1)-0.4/p^2+0.6/p=(p^2+0.2p-0.4)/(p^3+p^2)
num=[1 0.2 -0.4]
den=[1 1 0 0]
H=tf(num,den)
  11 个评论
显示 9更早的评论
Azzi Abdelmalek
Azzi Abdelmalek 2013-6-5
Do you mean
h: your output signal
m,c,k and F are constant
What about your input signal?
Sydney Flowers
Sydney Flowers 2013-6-5
F is a disturbing force, so, if i get you right, the input is initial value of the gap h, and omega, on which the F depends. and output is a new value of the gap.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Programming 的更多信息

标签

产品

Community Treasure Hunt

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

Start Hunting!

Translated by