[1] Hefei Univ Technol, Sch Mech & Automot Engn, Hefei 230009, Peoples R China
[2] Univ Michigan, Dept Elect & Comp Engn, Dearborn, MI 48128 USA
[3] Northwestern Polytech Univ, Sch Automat, Xian 710072, Peoples R China
[4] Kunming Univ Sci & Technol, Dept Elect Engn, Kunming 650500, Peoples R China