The new model regards the lengthofcurve section as its objective, in which main factors affecting 3 D trajectory design & control are considered quantitatively.
该模型以最短曲线段长度为目标函数，定量地考虑了影响轨道设计与控制的主要因素。
2
That means a vector that is at every point of the curve perpendicular to the curve and has length one.
也就是，曲线每一点上,垂直于曲线，模长为1的向量。
3
Similarly, this distance, the lengthof delta r is not exactly the length along the curve.