Then a low pass filter is designed to filter high - frequency noise in data . and smooth data again by means of central interpolation algorithm ; helicopter model with multi input single output are identified respectively in ls method and ml method ( 2 )剔除并补正了飞行实验数据中的野值；设计了一个低通滤波器来滤除数据中的高频噪声；用中心插值算法对数据二次平滑。
