二阶系统响应调整时间计算的修正

对于欠阻尼二阶系统，计算其单位阶跃响应的指标调整时间一直采用经典的近似方法，通过对经典计算方法的误差分析，推出了２种新的计算方法，相似三角形法和正弦曲线法，新方法使取代曲线由包张改为与响应曲线非常接近的一段直线和一段１／４周期的不同衰减正弦曲线，从而使计算误差大大减小，这将有益于提高系统性能分析的质量。

Correction of the Formula of Response Regulation Time in Second-Order System

With second- order system of lacking damper,the formula of regulation time of unit step re- sponse always is a classical approximation.With this approximation,detailed error analysis was complet- ed,and two new methods were proposed:the like triangle method and the sinusoid method.A length of straightline and a length of undamped sinusoid of1 / 4 period replace the envelop as the response.By the new methods,calculation error is greatly reduced and system character analysis is completed with advan- tage.