系统在欠阻尼情况时的单位跃迁响应为：

<script type="math/tex; mode=display" id="MathJax-Element-327">c(t)=1-\frac{e^{-\zeta\omega_nt}}{\sqrt{1-\zeta^2}}sin(\omega_dt+\theta)</script>
其中ωd=ωn1−ζ2−−−−−√<script type="math/tex" id="MathJax-Element-328">\omega_d=\omega_n\sqrt{1-\zeta^2}</script>，θ=arctan1−ζ2√ζ<script type="math/tex" id="MathJax-Element-329">\theta=arctan\frac{\sqrt{1-\zeta^2}}{\zeta}</script>或θ=arccosζ<script type="math/tex" id="MathJax-Element-330">\theta=arccos\zeta</script>。

上升时间

<script type="math/tex; mode=display" id="MathJax-Element-519">t_r=\frac{\pi-\theta}{\omega_d}=\frac{\pi-\theta}{\omega_n\sqrt{1-\zeta^2}}</script>
可见，当ωn<script type="math/tex" id="MathJax-Element-520">\omega_n</script>一定时，阻尼比ζ<script type="math/tex" id="MathJax-Element-521">\zeta</script>越大，上升时间tr<script type="math/tex" id="MathJax-Element-522">t_r</script>越长，当ζ<script type="math/tex" id="MathJax-Element-523">\zeta</script>一定时，wn<script type="math/tex" id="MathJax-Element-524">w_n</script>越大，则tr<script type="math/tex" id="MathJax-Element-525">t_r</script>越小。

峰值时间

<script type="math/tex; mode=display" id="MathJax-Element-1065">t_p=\frac{\pi}{\omega_d}=\frac{\pi}{\omega_n\sqrt{1-\zeta^2}}</script>
可见,当ζ<script type="math/tex" id="MathJax-Element-1066">\zeta</script>一定时，ωn<script type="math/tex" id="MathJax-Element-1067">\omega_n</script>越大，tp<script type="math/tex" id="MathJax-Element-1068">t_p</script>越小，反应速度越快。当ωn<script type="math/tex" id="MathJax-Element-1069">\omega_n</script>一定时，ζ<script type="math/tex" id="MathJax-Element-1070">\zeta</script>越小，tp<script type="math/tex" id="MathJax-Element-1071">t_p</script>也越小。由于ωd<script type="math/tex" id="MathJax-Element-1072">\omega_d</script>是闭环极点虚部的数值，ωd<script type="math/tex" id="MathJax-Element-1073">\omega_d</script>越大，则闭环极点到实轴的距离越远，因此，也可以说峰值时间tp<script type="math/tex" id="MathJax-Element-1074">t_p</script>与闭环极点到实轴的距离成反比。

超调量

<script type="math/tex; mode=display" id="MathJax-Element-1018">\sigma_p=e^{-\frac{\pi\zeta}{\sqrt{1-\zeta^2}}}\times100\%</script>
σp<script type="math/tex" id="MathJax-Element-1019">\sigma_p</script>只是ζ<script type="math/tex" id="MathJax-Element-1020">\zeta</script>的函数，与ωn<script type="math/tex" id="MathJax-Element-1021">\omega_n</script>无关，ζ<script type="math/tex" id="MathJax-Element-1022">\zeta</script>越小，σp<script type="math/tex" id="MathJax-Element-1023">\sigma_p</script>越大。当二阶系统的阻尼比ζ<script type="math/tex" id="MathJax-Element-1024">\zeta</script>确定后，即可求出对应的超调量σp<script type="math/tex" id="MathJax-Element-1025">\sigma_p</script>。

调节时间

<script type="math/tex; mode=display" id="MathJax-Element-1165">t_s\approx\frac{3}{\zeta\omega_n}(\Delta=0.05)和t_s\approx\frac{t}{\zeta\omega_n}(\Delta=0.02)</script>
调节时间ts<script type="math/tex" id="MathJax-Element-1166">t_s</script>近似于ζωn<script type="math/tex" id="MathJax-Element-1167">\zeta\omega_n</script>成反比。由于ζωn<script type="math/tex" id="MathJax-Element-1168">\zeta\omega_n</script>是闭环极点实部的数值，ζωn<script type="math/tex" id="MathJax-Element-1169">\zeta\omega_n</script>越大越大，则闭环极点到虚轴距离越远。