| 1. | At ancient times , people were navigated by means of sun , fixed stars , etc . , while currently the common navigation systems are astronomic navigation , inertial navigation and radio navigation 以前,人们主要利用太阳、星星等自然天体。现在人们利用的导航系统主要有:天文导航系统、惯性导航系统、无线电导航系统三大类。 |