Corresponding author. Tel.: + 86 10 82317745. E-mail addresses: bian_bys@buaa.edu.cn (Y. Bian),Bian Yushu received his Ph.D. degree from Beihang University in 1998 and now is an associate professor at Beihang University. His main research interests are flexible manipulators and vibration control. E-mail addresses: gaozhihui@buaa.edu.cn (Z. Gao). Gao Zhihui received her Ph.D. degree from Beihang University in 2007 and now is an associate professor at Beihang University. Her main research interests are flexible manipulators, kinematic and dynamic analysis.