传递函数推导： G ( s ) = ω n 2 s 2 + 2 ζ ω n s H ( s ) = 1 G(s) = \frac{\omega_n^2}{s^2+2\zeta\omega_ns} \qquad H(s)=1 G(s)=s2+2ζωn​sωn2​​H(s)=1 by框图化简，闭环传递函数为 ϕ c l = G ( s ) 1 + G ( s ) H ( s ) = ω n 2 s 2 + 2 ζ ω n s + ω n 2 \phi_{cl}=\frac{G(s)}{1+G(s)H(s)}=\frac{\omega_n^2}{s^2+2\zeta\omega_ns+\omega_n^2} ϕcl​=1+G(s)H(s)G(s)​=s2+2ζωn​s+ωn2​ωn2​​