说明：  求系统串联滞后校正器传递函数的函数 ，其中sope是系统的开环传递函数，当key=1时，var为gama，是根据要求校正后的相角 稳定裕度计算之后校正器；当key=2时，var=wc，则是 根据要求校正后的剪切频率计算校正器。
(Demand system is connected lag compensator transfer function of the function, which sope is the system open-loop transfer function, when key = 1 时, var is gama, is adjusted according to the phase angle required stability margin calculation after corrector when key = 2, var = wc, is the required shear frequencies after correction corrector.)