[1] Northwestern Polytech Univ, Sch Aeronaut, Xian 710072, Shaanxi, Peoples R China
[2] Northwestern Polytech Univ, State IJR Ctr Aerosp Design & Addit Mfg, Sch Mech Engn, Xian, Peoples R China
[3] Northwestern Polytech Univ, Unmanned Syst Res Inst, Xian 710072, Shaanxi, Peoples R China
[4] Univ Portsmouth, Sch Energy & Elect Engn, Portsmouth PO1 3DJ, England