1. Navigation College, Dalian Maritime University, Dalian, Liaoning, P. R. China
2. College of Science, Liaoning University of Technology, Jinzhou, Liaoning, P. R. China
3. National Key Laboratory of Unmanned Aerial Vehicle Technology, the National Key Laboratory of Aerospace Power System and Plasma Technology, and the College of Air Traffic Control and Navigation, Air Force Engineering University, Xi’an, Shanxi, P. R. China