说明：  参考《频域采样三角级数法模拟轨道不平顺信号》，以公路C级路面为例，产生路面谱，用于Adams car中整车仿真
(Refer to " frequency domain samples trigonometric series Law Moot track irregularity signal" to the highway C-level road, for example, to produce road spectrum for Adams car in vehicle simulation)