[1] Northwestern Polytech Univ, Sch Mech Engn, Key Lab Ind Engn & Intelligent Mfg, Minist Ind & Informat Technol, Xian 710072, Peoples R China
[2] Southern Univ Sci & Technol, Dept Mech & Energy Engn, Shenzhen 518055, Peoples R China
[3] Tsinghua Univ, Sch Software, Beijing 100084, Peoples R China
[4] Portland State Univ, Dept Elect & Comp Engn, Portland, OR 97207 USA