We propose adding a term that is related to the fourth power of offset into the traveltime equation, and expressed it by a fraction expansion. 为此，在时距关系中增加含炮检距的四次项，并采用分式展开法表示该四次项，同时引入远偏移距收敛因子。
In order to eliminate buffeting caused by exponentially reaching law, an idempotence term is introduced to make the control law smooth. 引入幂次项进行平滑设计，以减少指数趋近律引起的抖振。
