generating wrong Nyquist plot of tf
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i have been trying to plot nyquist plot of following transfer funtion but i am getting wrong.
sys =(s+3)/(s^2*(s-3))
when i tries to plot it using control technique i am getting different plot
please help
2 个评论
Paul
2021-5-28
What is your code and why do you think the result is wrong?
keshav agrawal
2021-5-28
the code is
s = tf('s')
sys =(s+3)/(s^2*(s-3))
nyquist(sys)
the plot i got from this is
the nyquist plot i am expecting should be like this :-
采纳的回答
Paul
2021-5-28
0 个投票
Keep in mind that nyquist() doesn't draw the arc at infinity due to the double pole at the origin.
If you zoom in around the origin on the Nyquist plot produced by nyquist(), you'll see that the plot crosses the imaginary axis at a value of around 0.1*j and approaches the origin from the left, as in your sketch.
更多回答（1 个）
Girijashankar Sahoo
2021-5-28
编辑：Girijashankar Sahoo
2021-5-28
0 个投票
sys=tf([0 0 1 3],[1 -3 0 0])
nyquist(sys)
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